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Sample records for centrifugal blood pump

  1. Centrifugal blood pumps for various clinical needs.

    PubMed

    Ichikawa, Seiji; Nosé, Yukihiko

    2002-11-01

    During the past 10 years, different types of blood pumps were developed to address various clinical needs. The Nikkiso centrifugal blood pump was developed for cardiopulmonary bypass application. This blood pump has been widely used in Japan in more than 20% of the cardiopulmonary bypass procedures. The Kyocera C1E3 Gryo pump was developed for short-term circulatory assistance and extracorporeal membrane oxygenation application for up to 2 weeks. This blood pump has been clinically used for up to 28 days without any blood clot formation. Through Phase I of the Japanese government New Energy and Industrial Technology Development Organization (NEDO) program, a chronically implanted centrifugal pump for left ventricular assistance was developed. This pump has already demonstrated its effectiveness, safety, and durability as a 2 year blood pump through in vitro and in vivo experiments. Currently, it is in the process of being converted from an experimental to a clinical device. Through Phase II of the NEDO program, a permanently implantable biventricular assist centrifugal blood pump system is under development. It has demonstrated that the previously mentioned left ventricular assist device blood pump is easily converted into a right ventricular assist pump by simply adding a spacer between the pump and the actuator. This communication discusses the historical development strategies for centrifugal blood pumps and their current status for different clinical needs.

  2. [Hemodynamic analysis of a centrifugal blood pump].

    PubMed

    Wang, Yang; Yang, Ming; Xu, Zihao; Zhuang, Xiaoqi; Li, Qilei; Xu, Liang

    2015-01-01

    This paper built the mathematical model of a centrifugal blood pump, which was designed by ourselves, combined it with that of the human cardiovascular system and simulated the coupling system using Matlab. Then we set up the experiment platform, linked the blood pump to mock human cardiovascular system in case of three-stage heart failure, and measured aortic pressure and flow under different speed. The comparison between experiment results and simulation results not only indicates the coupling model is correct and the blood pump works well, but also shows that with the increase of blood pump speed, the pulsation of aortic pressure and flow will be reduced, this situation will affect the structure and function of blood vessels.

  3. Development of an implantable centrifugal blood pump.

    PubMed

    Goldstein, A H; Pacella, J J; Trumble, D R; Clark, R E

    1992-01-01

    The efficacy of centrifugal pumps for short-term (0-30 days) ventricular support has been widely reported and favorably compared with pulsatile systems. A small, durable, implantable centrifugal blood pump is being developed for medium-term use (up to 6 months). The pump is based on the Medtronic Hemadyne system that has existed in multiple forms over the past 30 years. The pump is approximately the size of a tennis ball, weighs 240 g, and is comprised of a 2.5 cm plastic impeller driven by a radially coupled brushless DC motor. In vitro hydraulic performance was recorded over a wide range of flow conditions on a mock circulatory loop. The pump generated 7 L/min flow against an afterload of 100 mmHg pressure, with a maximum power draw of 10.4 watts. Pulsatile flow was preserved when placed in conjunction with a simulated left ventricle. In vivo testing was performed in 10 healthy sheep for 10-292 hr. Heparin was used to facilitate cannulation, and no anticoagulation was administered after pump implantation. Blood chemistries reflecting hematologic, pulmonary, renal, and hepatic functions were recorded and demonstrated no adverse effects with normal pump operation. Complications were related to kinking of blood conduits and thrombus formation within the cannulae. These results are encouraging and warrant further studies to prove feasibility of this pump as a medium-term implantable ventricular assist device.

  4. Effects of scaling on centrifugal blood pumps.

    PubMed

    Wong, Yew Wah; Chan, Weng Kong; Yu, S C M; Chua, Leok Poh

    2002-11-01

    Experimental studies on the effects of scaling on the performance of centrifugal blood pumps were conducted in a closed-loop test rig. For the prototype, eight different impellers of the same outer diameter of 25 mm were tested at 1,500, 2,000, and 2,500 revolutions per minute (rpm) using blood analog as fluid medium. This corresponds to Reynolds numbers (Re) of 25,900, 34,500, and 43,200, respectively. The results indicated that the nondimensional pump characteristic is a function of Re. This is understandable since the typical operating Re for centrifugal blood pumps is less than 100,000. Thus, the effects of scaling cannot be ignored for centrifugal blood pumps. Experiments on a 5x scaled-up model have also indicated that the scaled-up model is more efficient than the prototype model. Our results showed that in the range of Re tested, the nondimensional head versus flow curve is a function of Re to the power of approximately 0.25. It is observed that the nondimensional head versus flow is a function of diameter ratio to the power of 0.2.

  5. Design of a centrifugal blood pump: Heart Turcica Centrifugal.

    PubMed

    Demir, Onur; Biyikli, Emre; Lazoglu, Ismail; Kucukaksu, Suha

    2011-07-01

    A prototype of a new implantable centrifugal blood pump system named Heart Turcica Centrifugal (HTC) was developed as a left ventricular assist device (LVAD) for the treatment of end-stage cardiac failure. In the development of HTC, effects of blade height and volute tongue profiles on the hydraulic and hemolytic performances of the pump were investigated. As a result, the prototype was manufactured using the best blade height and volute tongue profiles. Performance of the prototype model was experimentally evaluated in a closed-loop flow system using water as the medium. The hydraulic performance requirement of an LVAD (5 L/min flow rate against a pressure difference of 100 mm Hg) was attained at 2800 rpm rotational speed.

  6. [Centrifugal blood pumps (new possibilities of design improvement)].

    PubMed

    Leshchinskiĭ, B M; Itkin, G P; Zimin, N K

    1992-01-01

    Based on an analysis of 300 world information sources, 19 types of centrifugal blood pumps were ascertained. Five new designs suggested have an idea in common: combination of the inlet of the disk pump and of the outlet of the impeller pump. This allows uniting the merits of the above pumps and excluding their shortcomings. The designs suggested make it possible to solve the two basic problems: hemolysis and thrombogenesis inside the pumps. The use of the pumps designed on such a basis will afford a simple and reliable approach to heart function replacement.

  7. A multiple disk centrifugal pump as a blood flow device.

    PubMed

    Miller, G E; Etter, B D; Dorsi, J M

    1990-02-01

    A multiple disk, shear force, valveless centrifugal pump was studied to determine its suitability as a blood flow device. A pulsatile version of the Tesla viscous flow turbine was designed by modifying the original steady flow pump concept to produce physiological pressures and flows with the aid of controlling circuitry. Pressures and flows from this pump were compared to a Harvard Apparatus pulsatile piston pump. Both pumps were connected to an artificial circulatory system. Frequency and systolic duration were varied over a range of physiological conditions for both pumps. The results indicated that the Tesla pump, operating in a pulsatile mode, is capable of producing physiologic pressures and flows similar to the Harvard pump and other pulsatile blood pumps.

  8. Control of centrifugal blood pump based on the motor current.

    PubMed

    Iijima, T; Inamoto, T; Nogawa, M; Takatani, S

    1997-07-01

    In this study, centrifugal pump performance was examined in a mock circulatory loop to derive an automatic pump rotational speed (rpm) control method. The pivot bearing supported sealless centrifugal pump was placed in the left ventricular apex to aorta bypass mode. The pneumatic pulsatile ventricle was used to simulate the natural ventricle. To simulate the suction effect in the ventricle, a collapsible rubber tube was placed in the inflow port of the centrifugal pump in series with the apex of the simulated ventricle. Experimentally, the centrifugal pump speed (rpm) was gradually increased to simulate the suction effect. The pump flow through the centrifugal pump measured by an electromagnetic flowmeter, the aortic pressure, and the motor current were continuously digitized at 100 Hz and stored in a personal computer. The analysis of the cross-spectral density between the pump flow and motor current waveforms revealed that 2 waveforms were highly correlated at the frequency range between 0 and 4 Hz, with the coherence and phase angles being close to 1.0 and 0 degree, respectively. The fast Fourier transform analysis of the motor current indicated that the second harmonic component of the motor current power density increased with the occurrence of the suction effect in the circuit. The ratio of the fundamental to the second harmonic component decreased less than 1.3 as the suction effect developed in the circuit. It is possible to detect and prevent the suction effect of the centrifugal blood pump in the natural ventricle through analysis of the motor current waveform.

  9. Performance of a newly developed implantable centrifugal blood pump.

    PubMed

    Tsukiya, T; Taenaka, Y; Tatsumi, E; Takano, H

    2001-01-01

    The performance of the newly developed implantable centrifugal blood pump was investigated in vitro. The pump was developed with the end goal of building a versatile system that includes a left ventricular assist system with an internal secondary battery or an implantable biventricular assist system with two implantable blood pumps. The hydrodynamic characteristics and efficiency of the blood pump were evaluated, and the mechanical damage to the blood caused by the blood pump was assessed through a hemolysis test using fresh goat blood. The pump could generate 120 mm Hg at a flow rate of 5 L/min and a motor speed of 2,500 rpm. The electric input power to the pump was approximately 5 watts under these working conditions. The hemolysis caused by the pump was a bit higher than that by the former model, but stayed within an acceptable range. Performance of the pump in vitro was considered sufficient for a left ventricular assist device, although further design improvement is necessary in terms of hemolysis and system efficiency to improve biocompatibility of the pump.

  10. A new blood pump for cardiopulmonary bypass: the HiFlow centrifugal pump.

    PubMed

    Göbel, C; Eilers, R; Reul, H; Schwindke, P; Jörger, M; Rau, G

    1997-07-01

    Centrifugal blood pumps are considered to be generally superior to the traditionally used roller pumps in cardiopulmonary bypass. In our institute a new lightweight centrifugal sealless blood pump with a unique spherical thrust bearing and with a magnetic coupling was developed, the HiFlow. The small design makes the pump suitable for applications in complex devices or close to a patient. Hemolysis tests were carried out in which the BioMedicus pump BP-80 and a roller pump were used as reference. The centrifugal pump HiFlow showed the least blood trauma within the group of investigated pumps. In summary, the HiFlow pump concept with its low priming volume and limited contact surfaces shows great potential for clinical applications in cardiopulmonary bypass. Also, the possibility of using the pump as a short-term assist device with an option of a pulsatile driving mode was demonstrated.

  11. Extracorporeal membrane oxygenator compatible with centrifugal blood pumps.

    PubMed

    Motomura, Tadashi; Maeda, Tomohiro; Kawahito, Shinji; Matsui, Takahiro; Ichikawa, Seiji; Ishitoya, Hiroshi; Kawamura, Masaki; Nishimura, Ikuya; Shinohara, Toshiyuki; Oestmann, Daniel; Glueck, Julia; Kawaguchi, Yoichiro; Sato, Koshiro; Nosé, Yukihiko

    2002-11-01

    Coil-type silicone membrane oxygenators can only be used with roller blood pumps due to the resistance from the high blood flow. Therefore, during extracorporeal membrane oxygenation (ECMO) treatment, the combination of a roller pump and an oxygenator with a high blood flow resistance will induce severe hemolysis, which is a serious problem. A silicone rubber, hollow fiber membrane oxygenator that has a low blood flow resistance was developed and evaluated with centrifugal pumps. During in vitro tests, sufficient gas transfer was demonstrated with a blood flow less than 3 L/min. Blood flow resistance was 18 mm Hg at 1 L/min blood flow. This oxygenator module was combined with the Gyro C1E3 (Kyocera, Japan), and veno-arterial ECMO was established on a Dexter strain calf. An ex vivo experiment was performed for 3 days with stable gas performance and low blood flow resistance. The combination of this oxygenator and centrifugal pump may be advantageous to enhance biocompatibility and have less blood trauma characteristics.

  12. A review of leakage flow in centrifugal blood pumps.

    PubMed

    Chan, Weng-Kong; Wong, Yew-Wah

    2006-05-01

    This article presents a new approach in determining the functional relationship between the leakage flow in a centrifugal blood pump and various parameters that affect it. While high leakage flow in a blood pump is essential for good washout and can help prevent thrombus formation, excessive leakage flow will result in higher fluid shear stress that may lead to hemolysis. Dimensional analysis is employed to provide a functional relationship between leakage flow rate and other important parameters governing the operation of a centrifugal blood pump. Results showed that pump performance with a smaller gap clearance is clearly superior compared to those of two other similar pumps with larger gap clearances. It was also observed that the nondimensional leakage flow rate varies almost linearly with dimensionless pump head. It also decreases with increasing volume flow rate. A smaller gap clearance will also increase the flow resistance and hence, decrease the nondimensional leakage flow rate. Increasing surface roughness, length of the gap clearance passage, or loss coefficient of the gap geometry will increase losses and hence, decrease the leakage flow rate. It is also interesting to note that for a given pump and gap clearance geometry, the nondimensional leakage flow rate is almost independent of the Reynolds number when specific speed is constant.

  13. Design considerations of volute geometry of a centrifugal blood pump.

    PubMed

    Chan, Weng Kong; Wong, Yew Wah; Hu, Wei

    2005-12-01

    This article compares two different design techniques that are conventionally used in the design of volutes for centrifugal pumps. The imbalanced forces due to the geometry of the volute need to be taken into consideration especially in centrifugal blood pumps with magnetically suspended impeller. A reduction of these forces can reduce the instability of the impeller motion as well as the power needed to counteract its influence. Volutes using the constant angular momentum (CAM) and the constant mean velocity (CMV) methods were developed and modeled numerically. The computational results on the effect of volute geometry on the performance of a centrifugal blood pump impeller for six different volutes are presented here. For volutes designed using the CAM method, model B (volute expansion angle of 3 degrees ) had the lowest radial force of 0.26 N while the pressure head generated was 12,900 Pa. For volutes designed using the CMV method, model F (1.6 m/s) had the lowest imbalanced force of 0.45 N. However, the pressure developed by this pump was also one of the lowest at 10,652 Pa. Furthermore, when the peak scalar stresses and the mean exposure time of particles for all designs were determined using Lagrangian particle tracking method, it was observed that in general, the peak scalar stresses in CAM designed volutes are lower than those designed using CMV method. The mean exposure time of particles in the pump ranged from 400 to 500 ms. The simulation results showed that the volute designed using CAM method was superior to that of a CMV volute in terms of the magnitude of the radial force and the peak scalar stresses for the same pressure head generated. Results show that the design of volutes for blood pumps should go beyond conventional empirical methods to obtain optimal results.

  14. Magnetically suspended centrifugal blood pump with a radial magnetic driver.

    PubMed

    Hoshi, Hideo; Katakoa, Kiroyuki; Ohuchi, Katsuhiro; Asama, Jun-ichi; Shinshi, Tadahiko; Shimokohbe, Akira; Takatani, Setsuo

    2005-01-01

    A new magnetic bearing has been designed to achieve a low electronic power requirement and high stiffness. The magnetic bearing consists of 1) radial passive forces between the permanent magnet ring mounted inside the impeller rotor and the electromagnet core materials in the pump casing and 2) radial active forces generated by the electromagnets using the two gap sensor signals. The magnetic bearing was assembled into a centrifugal rotary blood pump (CRBP) driven with a radial, magnetic coupled driver. The impeller vane shape was designed based upon the computational fluid dynamic simulation. The diameter and height of the CRBP were 75 mm and 50 mm, respectively. The magnetic bearing system required the power of 1.0-1.4 W. The radial impeller movement was controlled to within +/- 10 microm. High stiffness in the noncontrolled axes, Z, phi, and theta, was obtained by the passive magnetic forces. The pump flow of 5 L/min against 100 mm Hg head pressure was obtained at 1,800 rpm with the electrical to hydraulic efficiency being greater than 15%. The Normalized Index of Hemolysis (NIH) of the magnetic bearing CRBP was one fifth of the BioPump BP-80 and one half of the NIKKISO HPM-15 after 4 hours. The newly designed magnetic bearing with two degrees of freedom control in combination with optimized impeller vane was successful in achieving an excellent hemolytic performance in comparison with the clinical centrifugal blood pumps.

  15. An implantable centrifugal blood pump for long term circulatory support.

    PubMed

    Yamazaki, K; Litwak, P; Kormos, R L; Mori, T; Tagusari, O; Antaki, J F; Kameneva, M; Watach, M; Gordon, L; Umezu, M; Tomioka, J; Koyanagi, H; Griffith, B P

    1997-01-01

    A compact centrifugal blood pump was developed as an implantable left ventricular assist system. The impeller diameter is 40 mm and the pump dimensions are 55 x 64 mm. This first prototype was fabricated from titanium alloy, resulting in a pump weight of 400 g including a brushless DC motor. Weight of the second prototype pump was reduced to 280 g. The entire blood contacting surface is coated with diamond like carbon to improve blood compatibility. Flow rates of over 7 L/min against 100 mmHg pressure at 2,500 rpm with 9 W total power consumption have been measured. A newly designed mechanical seal with a recirculating purge system ("Cool-Seal") is used as a shaft seal. In this seal system, seal temperature is kept under 40 degrees C to prevent heat denaturation of blood proteins. Purge fluid also cools the pump motor coil and journal bearing. The purge fluid is continuously purified and sterilized by an ultrafiltration filter incorporated into the paracorporeal drive console. In vitro experiments with bovine blood demonstrated an acceptably low hemolysis rate (normalized index of hemolysis = 0.005 +/- 0.002 g/100 L). In vivo experiments are currently ongoing using calves. Via left thoracotomy, left ventricular apex-descending aorta bypass was performed utilizing a PTFE (Polytetrafluoroethylene) vascular graft, with the pump placed in the left thoracic cavity. In two in vivo experiments, pump flow rate was maintained at 5-8 L/min, and pump power consumption remained stable at 9-10 W. All plasma free hemoglobin levels were measured at < 15 mg/dl. The seal system has demonstrated good seal capability with negligible purge fluid consumption (< 0.5 ml/ day). Both animals remain under observation after 162 and 91 days of continuous pump function.

  16. Magnetically suspended centrifugal blood pump with a self bearing motor.

    PubMed

    Masuzawa, Toru; Onuma, Hiroyuki; Kim, Seung-Jong; Okada, Yohji

    2002-01-01

    A magnetically suspended centrifugal blood pump with a self bearing motor has been developed for long-term ventricular assistance. A rotor of the self bearing motor is actively suspended and rotated by an electromagnetic field without mechanical bearings. Radial position of the rotor is controlled actively, and axial position of the rotor is passively stable within the thin rotor structure. An open impeller and a semiopened impeller were examined to determine the best impeller structure. The outer diameter and height of the impeller are 63 and 34 mm, respectively. Both the impellers indicated similar pump performance. Single volute and double volute structures were also tested to confirm the performance of the double volute. Power consumption for levitation and radial displacement of the impeller with a rotational speed of 1,500 rpm were 0.7 W and 0.04 mm in the double volute, while those in the single volute were 1.3 W and 0.07 mm, respectively. The stator of the self bearing motor was redesigned to avoid magnetic saturation and improve motor performance. Maximum flow rate and pressure head were 9 L/min and 250 mm Hg, respectively. The developed magnetically suspended centrifugal blood pump is a candidate for an implantable left ventricular assist device.

  17. Prediction of leakage flow in a shrouded centrifugal blood pump.

    PubMed

    Teo, Ji-Bin; Chan, Weng-Kong; Wong, Yew-Wah

    2010-09-01

    This article proposes a phenomenological model to predict the leakage flow in the clearance gap of shrouded centrifugal blood pumps. A good washout in the gap clearance between the rotating impeller surfaces and volute casing is essential to avoid thrombosis. However, excessive leakage flow will result in higher fluid shear stress that may lead to hemolysis. Computational fluid dynamics (CFD) analysis was performed to investigate the leakage flow in a miniaturized shrouded centrifugal blood pump operating at a speed of 2000 rpm. Based on an analytical model derived earlier, a phenomenological model is proposed to predict the leakage flow. The leakage flow rate is found to be proportional to h(α) , where h is the gap size and the exponent α ranges from 2.955 to 3.15 for corresponding gap sizes of 0.2-0.5 mm. In addition, it is observed that α is a linear function of the gap size h. The exponent α compensates for the variation of pressure difference along the circumferential direction as well as inertia effects that are dominant for larger gap clearances. The proposed model displays good agreement with computational results. The CFD analysis also showed that for larger gap sizes, the total leakage flow rate is of the same order of magnitude as the operating flow rate, thus suggesting low volumetric efficiency.

  18. Magnetically suspended centrifugal blood pump with an axially levitated motor.

    PubMed

    Masuzawa, Toru; Ezoe, Shiroh; Kato, Tsuyoshi; Okada, Yohji

    2003-07-01

    The longevity of a rotary blood pump is mainly determined by the durability of its wearing mechanical parts such as bearings and seals. Magnetic suspension techniques can be used to eliminate these mechanical parts altogether. This article describes a magnetically suspended centrifugal blood pump using an axially levitated motor. The motor comprises an upper stator, a bottom stator, and a levitated rotor-impeller between the stators. The upper stator has permanent magnets to generate an attractive axial bias force on the rotor and electric magnets to control the inclination of the rotor. The bottom stator has electric magnets to generate attractive forces and rotating torque to control the axial displacement and rotation of the rotor. The radial displacement of the rotor is restricted by passive stability. A shrouded impeller is integrated within the rotor. The performance of the magnetic suspension and pump were evaluated in a closed mock loop circuit filled with water. The maximum amplitude of the rotor displacement in the axial direction was only 0.06 mm. The maximum possible rotational speed during levitation was 1,600 rpm. The maximum pressure head and flow rate were 120 mm Hg and 7 L/min, respectively. The pump shows promise as a ventricular assist device.

  19. In vivo evaluation of centrifugal blood pump for cardiopulmonary bypass-Spiral Pump.

    PubMed

    da Silva, Cibele; da Silva, Bruno Utiyama; Leme, Juliana; Uebelhart, Beatriz; Dinkhuysen, Jarbas; Biscegli, José F; Andrade, Aron; Zavaglia, Cecília

    2013-11-01

    The Spiral Pump (SP), a centrifugal blood pump for cardiopulmonary bypass (CPB), has been developed at the Dante Pazzanese Institute of Cardiology/Adib Jatene Foundation laboratories, with support from Sintegra Company (Pompeia, Brazil). The SP is a disposable pump with an internal rotor-a conically shaped fuse with double entrance threads. This rotor is supported by two ball bearings, attached to a stainless steel shaft fixed to the housing base. Worm gears provide axial motion to the blood column, and the rotational motion of the conically shaped impeller generates a centrifugal pumping effect, improving pump efficiency without increasing hemolysis. In vitro tests were performed to evaluate the SP's hydrodynamic performance, and in vivo experiments were performed to evaluate hemodynamic impact during usual CPB. A commercially available centrifugal blood pump was used as reference. In vivo experiments were conducted in six male pigs weighing between 60 and 90 kg, placed on CPB for 6 h each. Blood samples were collected just before CPB (T0) and after every hour of CPB (T1-T6) for hemolysis determination and laboratory tests (hematological and biochemical). Values of blood pressure, mean flow, pump rotational speed, and corporeal temperature were recorded. Also, ergonomic conditions were recorded: presence of noise, difficulty in removing air bubbles, trouble in installing the pump in the drive module (console), and difficulties in mounting the CPB circuit. Comparing the laboratory and hemolysis results for the SP with those of the reference pump, we can conclude that there is no significant difference between the two devices. In addition, reports made by medical staff and perfusionists described a close similarity between the two devices. During in vivo experiments, the SP maintained blood flow and pressure at physiological levels, consistent with those applied in cardiac surgery with CPB, without presenting any malfunction. Also, the SP needed lower rotational

  20. The Impact of Roller Pump vs. Centrifugal Pump on Homologous Blood Transfusion in Pediatric Cardiac Surgery.

    PubMed

    Datt, Bharat; Nguyen, Moui B; Plancher, Gary; Ruzmetov, Mark; O'Brien, Michael; Kube, Alicia; Munro, Hamish M; Pourmoghadam, Kamal K; DeCampli, William M

    2017-03-01

    Centrifugal pumps are considered to be less destructive to blood elements (1) when compared to roller pumps. However, their large prime volumes render them unsuitable as arterial pumps in heart lung machine (HLM) circuitry for children. In November of 2014, the circuit at Arnold Palmer Hospital, a Biomedicus BP-50 with kinetic assist venous drainage (KAVD) and 1/4″ tubing was converted to a roller pump in the arterial position with gravity drainage. Vacuum-assisted venous drainage (VAVD) was mounted on the HLM as a backup, but not used. Tubing was changed to 3/16″ in the arterial line in patients <13 kg. A retrospective study with a total of 140 patients compared patients placed on cardiopulmonary bypass (CPB) with Biomedicus centrifugal pumps and KAVD (Centrifugal Group, n = 40) to those placed on CPB with roller pumps and gravity drainage (Roller Group, n = 100). Patients requiring extra-corporeal membrane oxygenation (ECMO)/cardio-pulmonary support (CPS) or undergoing a hybrid procedure were excluded. Re-operation or circulatory arrest patients were not excluded. Prime volumes decreased by 57% from 456 ± 34 mL in the Centrifugal Group to 197 ± 34 mL in the Roller Group (p < .001). There was a corresponding increase in hematocrit (HCT) of blood primes and also on CPB. Intraoperative homologous blood transfusions also decreased 55% from 422 mL in the Centrifugal Group to 231 mL in the Roller Group (p < .001). The Society of Thoracic Surgeons--European Association for Cardio-Thoracic Surgery (STAT) categorized intubation times and hospital length of stay (LOS) for all infants showed a trend toward reduction, but was not statistically significant. Overall mortality was 5% utilizing the centrifugal configuration and 0% in the roller pump cohort. We demonstrated that the transition to roller pumps in the arterial position of the HLM considerably reduced our priming volume and formed a basis for a comprehensive blood conservation program. By maintaining higher

  1. Concept designs of nonrotating-type centrifugal blood pump and basic study on output characteristics of the oscillating disk-type centrifugal pump.

    PubMed

    Kabei, N; Tuichiya, K; Sakurai, Y

    1994-09-01

    When designing a turbo-type blood pump as an artificial heart, the gap between a rotating shaft and a pump housing should be perfectly sealed to prevent any leakage or contamination through a seal. In addition, blood coagulation in a blood chamber must be avoided. To overcome these problems, we proposed five different nonrotating-type turbo pumps: a caudal-fin-type axial-flow pump, a caudal-fin-type centrifugal pump, a nutating-column-type centrifugal pump, a nutating-collapsible-tube-type centrifugal pump, and an oscillating-disk-type centrifugal pump. We selected and developed the oscillating-disk-type centrifugal pump that consists of a disk, a driving rod, a seal, an oscillation mechanism, and a pump housing. The disk is mounted on the end of the rod, which is connected to a high-speed DC motor through an oscillation mechanism. The rod and the disk do not rotate, but they oscillate in the pump housing. This movement of the disk generates forward fluid flow around the axis (i.e., the rotational fluid flow). Centrifugal force due to fluid rotation supports the pressure difference between the outlet and the inlet. The diameter of the disk is 39 mm, the maximum inner diameter of the pump housing is 40 mm, and the volume of the blood chamber for 25 degrees' oscillation is 16.9 ml. The performance of the pump was tested in a mock circulatory system.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. Jostra Rota Flow RF-30 pump system: a new centrifugal blood pump for cardiopulmonary bypass.

    PubMed

    Orime, Y; Shiono, M; Yagi, S; Yamamoto, T; Okumura, H; Nakata, K; Kimura, S; Hata, M; Sezai, A; Kashiwazaki, S; Choh, S; Negishi, N; Sezai, Y; Matsui, T; Suzuki, M

    2000-06-01

    The Rota Flow pump is a fully integrated centrifugal pump system in the Jostra heart-lung machine HL-20 with features such as a less friction mono-pivot bearing system, sealless pump housing, and spiral housing. To evaluate its biocompatibility, antithrombogenesity, and hemolysis, we used it as a main pump of cardiopulmonary bypass (CPB) in coronary artery bypass grafting (CABG) cases and compared it with the BioMedicus pump. From February 1999 to May 1999, 30 consecutive patients underwent CABG under conventional CPB. Fifteen cases were supported by the Rota Flow RF-32 (Group R), and the remaining 15 were pumped by the BioMedicus BP-80 (Group B). In both groups, the flow rate was controlled in an equivalent value. Blood sampling was as follows: preoperative, 60 min after, postoperative Days (POD) 0, 1, and 2. We evaluated the plasma free hemoglobin (fHb) as the hemolysis parameter, beta-thromboglobulin (beta-TG) and platelet factor IV (PF-4) as the platelet deterioration index, C3, C4, and CH50 as complement activation, coagulation function, fibrinolytic factor and thrombomodulin, nitric oxide (NO), and endothelin as endothelial deterioration. This system was very easily and simply controlled and had excellent response. Perioperative laboratory data were not markedly changed in either group. The Rota Flow demonstrated equivalent value of biocompatibility and hemolysis as compared with the BioMedicus BP-80, which is a standard centrifugal pump. After pumping, no thrombus formation or pivot wear was observed inside the pump. This atraumatic, small centrifugal pump is suitable not only for CPB but also for long-term circulatory support.

  3. The role of diastolic pump flow in centrifugal blood pump hemodynamics.

    PubMed

    Akimoto, T; Litwak, K N; Yamazaki, K; Litwak, P; Kihara, S I; Tagusari, O; Yamazaki, S I; Kameneva, M V; Watach, M J; Umezu, M; Tomioka, J; Kormos, R L; Koyanagi, H; Griffith, B P

    2001-09-01

    We tried to verify the hypothesis that increases in pump flow during diastole are matched by decreases in left ventricular (LV) output during systole. A calf (80 kg) was implanted with an implantable centrifugal blood pump (EVAHEART, SunMedical Technology Research Corp., Nagano, Japan) with left ventricle to aorta (LV-Ao) bypass, and parameters were recorded at different pump speeds under general anesthesia. Pump inflow and outflow pressure, arterial pressure, systemic and pulmonary blood flow, and electrocardiogram (ECG) were recorded on the computer every 5 ms. All parameters were separated into systolic and diastolic components and analyzed. The pulmonary flow was the same as the systemic flow during the study (p > 0.1). Systemic flow consisted of pump flow and LV output through the aortic valve. The ratio of systolic pump flow to pulmonary flow (51.3%) did not change significantly at variable pump speeds (p > 0.1). The other portions of the systemic flow were shared by the left ventricular output and the pump flow during diastole. When pump flow increased during diastole, there was a corresponding decrease in the LV output (Y = -1.068X + 51.462; R(insert)(2) = 0.9501). These show that pump diastolic flow may regulate expansion of the left ventricle in diastole.

  4. Computational fluid dynamics analysis of the pediatric tiny centrifugal blood pump (TinyPump).

    PubMed

    Kido, Kazuyuki; Hoshi, Hideo; Watanabe, Nobuo; Kataoka, Hiroyuki; Ohuchi, Katsuhiro; Asama, Junichi; Shinshi, Tadahiko; Yoshikawa, Masaharu; Takatani, Setsuo

    2006-05-01

    We have developed a tiny rotary centrifugal blood pump for the purpose of supporting circulation of children and infants. The pump is designed to provide a flow of 0.1-4.0 L/min against a head pressure of 50-120 mm Hg. The diameter of the impeller is 30 mm with six straight vanes. The impeller is supported by a hydrodynamic bearing at its center and rotated with a radial coupled magnetic driver. The bearing that supports rotation of the impeller of the tiny centrifugal blood pump is very critical to achieve durability, and clot-free and antihemolytic performance. In this study, computational fluid dynamics (CFD) analysis was performed to quantify the secondary flow through the hydrodynamic bearing at the center of the impeller and investigated the effects of bearing clearance on shear stress to optimize hemolytic performance of the pump. Two types of bearing clearance (0.1 and 0.2 mm) were studied. The wall shear stress of the 0.1-mm bearing clearance was lower than that of 0.2-mm bearing clearance at 2 L/min and 3000 rpm. This was because the axial component of the shear rate significantly decreased due to the narrower clearance even though the circumferential component of the shear rate increased. Hemolysis tests showed that the normalized index of hemolysis was reduced to 0.0076 g/100 L when the bearing clearance was reduced to 0.1 mm. It was found that the CFD prediction supported the experimental trend. The CFD is a useful tool for optimization of the hydrodynamic bearing design of the centrifugal rotary blood pump to optimize the performance of the pump in terms of mechanical effect on blood cell elements, durability of the bearing, and antithrombogenic performance.

  5. Hemocompatibility of a hydrodynamic levitation centrifugal blood pump.

    PubMed

    Yamane, Takashi; Maruyama, Osamu; Nishida, Masahiro; Kosaka, Ryo; Sugiyama, Daisuke; Miyamoto, Yusuke; Kawamura, Hiroshi; Kato, Takahisa; Sano, Takeshi; Okubo, Takeshi; Sankai, Yoshiyuki; Shigeta, Osamu; Tsutsui, Tatsuo

    2007-01-01

    A noncontact type centrifugal pump without any complicated control or sensing modules has been developed as a long-term implantable artificial heart. Centrifugal pumps with impellers levitated by original hydrodynamic bearings were designed and have been modified through numerical analyses and in vitro tests. The hemolysis level was reduced by changing the pressure distribution around the impeller and subsequently expanding the bearing gap. Thrombus formation in the bearing was examined with in vitro thrombogenesis tests and was reduced by changing the groove shapes to increase the bearing-gap flow to 3% of the external flow. Unnecessary vortices around the vanes were also eliminated by changing the number of vanes from four to six.

  6. [Numerical assessment of impeller features of centrifugal blood pump based on fast hemolysis approximation model].

    PubMed

    Shou, Chen; Guo, Yongjun; Su, Lei; Li, Yongqian

    2014-12-01

    The impeller profile, which is one of the most important factors, determines the creation of shear stress which leads to blood hemolysis in the internal flow of centrifugal blood pump. The investigation of the internal flow field in centrifugal blood pump and the estimation of the hemolysis within different impeller profiles will provide information to improve the performance of centrifugal blood pump. The SST kappa-omega with low Reynolds correction was used in our laboratory to study the internal flow fields for four kinds of impellers of centrifugal blood pump. The flow fields included distributions of pressure field, velocity field and shear stress field. In addition, a fast numerical hemolysis approximation was adopted to calculate the normalized index of hemolysis (NIH). The results indicated that the pressure field distribution in all kinds of blood pump were reasonable, but for the log spiral impeller pump, the vortex and backflow were much lower than those of the other pumps, and the high shear stress zone was just about 0.004%, and the NIH was 0.0089.

  7. A magnetically levitated centrifugal blood pump with a simple-structured disposable pump head.

    PubMed

    Hijikata, Wataru; Shinshi, Tadahiko; Asama, Junichi; Li, Lichuan; Hoshi, Hideo; Takatani, Setsuo; Shimokohbe, Akira

    2008-07-01

    A magnetically levitated centrifugal blood pump (MedTech Dispo) has been developed for use in a disposable extracorporeal system. The design of the pump is intended to eliminate mechanical contact with the impeller, to facilitate a simple disposable mechanism, and to reduce the blood-heating effects that are caused by motors and magnetic bearings. The bearing rotor attached to the impeller is suspended by a two degrees-of-freedom controlled radial magnetic bearing stator, which is situated outside the rotor. In the space inside the ringlike rotor, a magnetic coupling disk is placed to rotate the rotor and to ensure that the pump head is thermally isolated from the motor. In this system, the rotor can exhibit high passive stiffness due to the novel design of the closed magnetic circuits. The disposable pump head, which has a priming volume of 23 mL, consists of top and bottom housings, an impeller, and a rotor with a diameter of 50 mm. The pump can provide a head pressure of more than 300 mm Hg against a flow of 5 L/min. The normalized index of hemolysis of the MedTech Dispo is 0.0025 +/- 0.0005 g/100 L at 5 L/min against 250 mm Hg. This is one-seventh of the equivalent figure for a Bio Pump BPX-80 (Medtronic, Inc., Minneapolis, MN, USA), which has a value of 0.0170 +/- 0.0096 g/100 L. These results show that the MedTech Dispo offers high pumping performance and low blood trauma.

  8. Development of an implantable centrifugal blood pump for circulatory assist.

    PubMed

    Wakisaka, Y; Taenaka, Y; Chikanari, K; Okuzono, Y; Endo, S; Takano, H

    1997-01-01

    An implantable centrifugal pump (ICP) for prolonged circulatory assist has been developed, at 320 ml and 830 g. A central balancing hole was made in its impeller for better antithrombogenicity. Waterproofing and histocompatibility were supported by a silicone seal and a casing made of titanium and acrylic resin. Overall efficiency was 30% and normalized index of homolysis was 0.003 mg/dl, the same value as the BP-80, at a flow rate of 5 L/min and a head of 100 mmHg. Antithrombogenicity and hemolytic properties of the ICP were investigated in paracorporeal implantation in three goats (61-71 kg). Exothermicity, anatomic fit, and water tightness of the ICP were evaluated in intrathoracic implantation in an adult goat (66 kg). The ICP could run paracorporeally for 50, 200, and 381 days. There was no thrombus in the ICP after 381 days' pumping, and the ICP could run in the chest cavity for 40 days. The temperature of the motor rose 1.8 +/- 0.3 degrees C from that of the pleura. Moisture content of the seal remained normal. The ICP was completely covered with smooth fibrous tissue. Although a small area of atelectasis was found in the lingula, neither lung adhesion nor necrosis of the chest wall was observed. The ICP has satisfactory antithrombogenicity, hemolytic property, water tightness, anatomic fit, and exothermicity for use as an implantable circulatory assist device.

  9. Evaluation of cardiac function during left ventricular assist by a centrifugal blood pump.

    PubMed

    Kikugawa, D

    2000-08-01

    In this study, the effects on varying cardiac function during a left ventricular (LV) bypass from the apex to the descending aorta using a centrifugal blood pump were evaluated by analyzing the left ventricular pressure and the motor current of the centrifugal pump in a mock circulatory loop. Failing heart models (preload 15 mm Hg, afterload 40 mm Hg) and normal heart models (preload 5 mm Hg, afterload 100 mm Hg) were simulated by adjusting the contractility of the latex rubber left ventricle. In Study 1, the bypass flow rate, left ventricular pressure, aortic pressure, and motor current levels were measured in each model as the centrifugal pump rpm were increased from 1,000 to 1,500 to 2,000. In Study 2, the pump rpm were fixed at 1,300, 1,500, and 1,700, and at each rpm, the left ventricular peak pressure was increased from 40 to 140 mm Hg by steps of 20 mm Hg. The same measurements as in Study 1 were performed. In Study 1, the bypass flow rate and mean aortic pressure both increased with the increase in pump rpm while the mean left ventricular pressure decreased. In Study 2, a fairly good correlation between the left ventricular pressure and the motor current of the centrifugal pump was obtained. These results suggest that cardiac function as indicated by left ventricular pressure may be estimated from a motor current analysis of the centrifugal blood pump during left heart bypass.

  10. Numerical analysis of the internal flow field in screw centrifugal blood pump based on CFD

    NASA Astrophysics Data System (ADS)

    Han, W.; Han, B. X.; Y Wang, H.; Shen, Z. J.

    2013-12-01

    As to the impeller blood pump, the high speed of the impeller, the local high shear force of the flow field and the flow dead region are the main reasons for blood damage. The screw centrifugal pump can effectively alleviate the problems of the high speed and the high shear stress for the impeller. The softness and non-destructiveness during the transfer process can effectively reduce the extent of the damage. By using CFD software, the characteristics of internal flow are analyzed in the screw centrifugal pump by exploring the distribution rules of the velocity, pressure and shear deformation rate of the blood when it flows through the impeller and the destructive effects of spiral blades on blood. The results show that: the design of magnetic levitation solves the sealing problems; the design of regurgitation holes solves the problem of the flow dead zone; the magnetic levitated microcirculation screw centrifugal pump can effectively avoid the vortex, turbulence and high shear forces generated while the blood is flowing through the pump. Since the distribution rules in the velocity field, pressure field and shear deformation rate of the blood in the blood pump are comparatively uniform and the gradient change is comparatively small, the blood damage is effectively reduced.

  11. Pediatric ECMO outcomes: comparison of centrifugal versus roller blood pumps using propensity score matching.

    PubMed

    Barrett, Cindy S; Jaggers, James J; Cook, E Francis; Graham, Dionne A; Yarlagadda, Vasmi V; Teele, Sarah A; Almond, Christopher S; Bratton, Susan L; Seeger, John D; Dalton, Heidi J; Rycus, Peter T; Laussen, Peter C; Thiagarajan, Ravi R

    2013-01-01

    Centrifugal blood pumps are being increasingly utilized in children supported with extracorporeal membrane oxygenation (ECMO). Our aim was to determine if survival and ECMO-related morbidities in children supported with venoarterial (VA) ECMO differed by blood pump type.Children aged less than 18 years who underwent VA ECMO support from 2007 to 2009 and reported to the Extracorporeal Life Support Organization registry were propensity score matched (Greedy 1:1 matching) using pre-ECMO characteristics.A total of 2,656 (centrifugal = 2,231, roller = 425) patients were identified and 548 patients (274 per pump type) were included in the propensity score-matched cohort. Children supported with centrifugal pumps had increased odds of hemolysis (odds ratio [OR], 4.03 95% confidence interval [CI], 2.37-6.87), hyperbilirubinemia (OR, 5.48; 95% CI, 2.62-11.49), need for inotropic support during ECMO (OR, 1.54; 95% CI, 1.09-2.17), metabolic alkalosis (blood pH > 7.6) during ECMO (OR, 3.13; 95% CI, 1.49-6.54), and acute renal failure (OR, 1.61; 95% CI, 1.10-2.39). Survival to hospital discharge did not differ by pump type.In a propensity score-matched cohort of pediatric ECMO patients, children supported with centrifugal pumps had increased odds of ECMO-related complications. There was no difference in survival between groups.

  12. Design of a small centrifugal blood pump with magnetic bearings.

    PubMed

    Jahanmir, Said; Hunsberger, Andrew Z; Ren, Zhaohui; Heshmat, Hooshang; Heshmat, Crystal; Tomaszewski, Michael J; Walton, James F

    2009-09-01

    Design of a blood pump with a magnetically levitated rotor requires rigorous evaluation of the magnetic bearing and motor requirements and analysis of rotor dynamics and hydraulic performance with attention to hemolysis and thrombosis potential. Given the desired geometric dimensions, the required operating speed, flow in both the main and wash flow regions, and magnetic bearing performance, one of several design approaches was selected for a new prototype. Based on the estimated operating speed and clearance between the rotor and stator, the motor characteristics and dimensions were estimated. The motor stiffness values were calculated and used along with the hydraulic loading due to the fluid motion to determine the best design for the axial and radial magnetic bearings. Radial and axial stability of the left ventricular assist device prototype was verified using finite element rotor dynamic analysis. The analysis indicated that the rotor could be completely levitated and spun to the desired operating speed with low power loss and no mechanical contact. In vitro experiments with a mock loop test setup were performed to evaluate the performance of the new blood pump prototype.

  13. [Study on optimal selection of structure of vaneless centrifugal blood pump with constraints on blood perfusion and on blood damage indexes].

    PubMed

    Hu, Zhaoyan; Pan, Youlian; Chen, Zhenglong; Zhang, Tianyi; Lu, Lijun

    2012-12-01

    This paper is aimed to study the optimal selection of structure of vaneless centrifugal blood pump. The optimal objective is determined according to requirements of clinical use. Possible schemes are generally worked out based on structural feature of vaneless centrifugal blood pump. The optimal structure is selected from possible schemes with constraints on blood perfusion and blood damage indexes. Using an optimal selection method one can find the optimum structure scheme from possible schemes effectively. The results of numerical simulation of optimal blood pump showed that the method of constraints of blood perfusion and blood damage is competent for the requirements of selection of the optimal blood pumps.

  14. [Research on flow characteristics in a non-blade centrifugal blood pump based on CFD technology].

    PubMed

    Cheng, Yunzhang; Luo, Binhai; Wu, Wenquan; Jiang, Lei

    2010-10-01

    The problem of thrombus and hemolysis in blood pump has always been an important topic to study in the development of the blood pump. Numbers of research results show that it is the complicated flow and the high shear stress of the mechanical movement that result in the thrombus and hemolysis. In this study, with the cooperation of Shanghai Children's Medical Center, we have used computational fluid dynamics (CFD) commercial software FLUENT to compute and analyze the flow characteristics in a non-blade centrifugal blood pump. The results figure out that this pump has a reasonable flow distribution and the shear stress distribution is under the critical broken state of red blood cell; meanwhile, there is less thrombus and hemolysis in this pump. So it is in the foreground for clinical use.

  15. Evaluation of erythrocyte flow at a bearing gap in a hydrodynamically levitated centrifugal blood pump.

    PubMed

    Murashige, Tomotaka; Kosaka, Ryo; Sakota, Daisuke; Nishida, Masahiro; Kawaguchi, Yasuo; Yamane, Takashi; Maruyama, Osamu

    2015-01-01

    We have developed a hydrodynamically levitated centrifugal blood pump for extracorporeal circulatory support. In the blood pump, a spiral groove bearing was adopted for a thrust bearing. In the spiral groove bearing, separation of erythrocytes and plasma by plasma skimming has been postulated to occur. However, it is not clarified that plasma skimming occurs in a spiral groove bearing. The purpose of this study is to verify whether plasma skimming occurs in the spiral groove bearing of a hydrodynamically levitated centrifugal blood pump. For evaluation of plasma skimming in the spiral groove bearing, an impeller levitation performance test using a laser focus displacement meter and a microscopic visualization test of erythrocyte flow using a high-speed microscope were conducted. Bovine blood diluted with autologous plasma to adjust hematocrit to 1.0% was used as a working fluid. Hematocrit on the ridge region in the spiral groove bearing was estimated using image analysis. As a result, hematocrits on the ridge region with gaps of 45 μm, 31 μm, and 25 μm were calculated as 1.0%, 0.6%, and 0.3%, respectively. Maximum skimming efficiency in this study was calculated as 70% with a gap of 25 μm. We confirmed that separation of erythrocyte and plasma occurred in the spiral groove bearing with decrease in bearing gap in a hydrodynamically levitated centrifugal blood pump.

  16. Numerical study of a centrifugal blood pump with different impeller profiles.

    PubMed

    Song, Guoliang; Chua, Leok Poh; Lim, Tau Meng

    2010-01-01

    Computational fluid dynamic simulations of the Kyoto-NTN magnetically suspended centrifugal blood pump with 16 forward-bending blades (16FB), 16 straight blades (16SB), and eight backward-bending blades (8BB) impellers were performed in this study. Commercial CFD software package FLUENT were used as the solver. The purpose of this study is to find out how the impeller blade profiles affect the inner flow and the performance of the centrifugal blood pump. The simulations were carried out with the same impeller rotating speed of 2,000 rpm and pump flow rate of 5 L/min to compare the three pump models. It was found that the 16SB impeller can produce higher pressure head than the 16FB and 8BB impellers under the same impeller rotating speed and pump flow rate. The flow particle tracing was carried out to estimate the blood damage level caused by the three different impeller profiles. It was found that the 16FB and 8BB models have caused the highest and lowest blood damage, respectively. The 16SB is recommended among the three pumps because it can generate the highest pressure head and induce mild blood damage index, although it was higher than that of the 8BB model.

  17. Development of a compact, sealless, tripod supported, magnetically driven centrifugal blood pump.

    PubMed

    Yuhki, A; Nogawa, M; Takatani, S

    2000-06-01

    In this study, a tripod supported sealless centrifugal blood pump was designed and fabricated for implantable application using a specially designed DC brushless motor. The tripod structure consists of 3 ceramic balls mounted at the bottom surface of the impeller moving in a polyethylene groove incorporated at the bottom pump casing. The follower magnet inside the impeller is coupled to the driver magnet of the motor outside the bottom pump casing, thus allowing the impeller to slide-rotate in the polyethylene groove as the motor turns. The pump driver has a weight of 230 g and a diameter of 60 mm. The acrylic pump housing has a weight of 220 g with the priming volume of 25 ml. At the pump rpm of 1,000 to 2,200, the generated head pressure ranged from 30 to 150 mm Hg with the maximum system efficiency being 12%. When the prototype pump was used in the pulsatile mock loop to assist the ventricle from its apex to the aorta, a strong correlation was obtained between the motor current and bypass flow waveforms. The waveform deformation index (WDI), defined as the ratio of the fundamental to the higher order harmonics of the motor current power spectral density, was computed to possibly detect the suction occurring inside the ventricle due to the prototype centrifugal pump. When the WDI was kept under the value of 0.20 by adjusting the motor rpm, it was successful in suppressing the suction due to the centrifugal pump in the ventricle. The prototype sealless, centrifugal pump together with the control method based on the motor current waveform analysis may offer an intermediate support of the failing left or right ventricle bridging to heart transplantation.

  18. Simple in vitro testing method for antithrombogenic evaluation of centrifugal blood pumps.

    PubMed

    Maruyama, Osamu; Tomari, Yosuke; Sugiyama, Daisuke; Nishida, Masahiro; Tsutsui, Tatsuo; Yamane, Takashi

    2009-01-01

    We developed a simple in vitro antithrombogenic testing method using a mock circulation system as used in the hemolysis tests to evaluate the antithrombogenicity of centrifugal blood pumps. This method was not designed to substitute for animal experiments but was intended to be a screening test method for selecting pumps robust enough to operate properly during animal experiments. In this study, we were able to maintain an almost constant activated clotting time for test blood for 10 hours by using both trisodium citrate and calcium chloride. We carried out the in vitro antithrombogenic testing of monopivot type centrifugal blood pumps (models DD3 and DD6) and hydrodynamic bearing pumps (models HH2 and HH7), which were developed at Advanced Industrial Science and Technology. Thrombus formation was not observed in the DD3 or DD6 pumps but occurred in the HH2 and HH7 pumps. The HH2 pump generated thrombi during a 1.5-hour ex vivo test, and the test was terminated. We expect this in vitro testing method to be useful for undertaking evaluations before animal experiments.

  19. Centrifugal blood pump with a hydraulically-levitated impeller for a permanently implantable biventricular assist device.

    PubMed

    Watanabe, Kuniyoshi; Ichikawa, Seiji; Asai, Toshimasa; Motomura, Tadashi; Hata, Atsushi; Ito, Seiichi; Shinohara, Toshiyuki; Tsujimura, Shinichi; Glueck, Julia A; Oestmann, Daniel J; Nosé, Yukihiko

    2004-06-01

    A permanently implantable biventricular assist device (BVAD) system has been developed with a centrifugal pump which is activated by a hydraulically-levitated impeller. The pump impeller floats hydraulically into the top contact position; this position prevents thrombus formation by creating a washout effect at the bottom bearing area, a common stagnant region. The pump was subjected to in vitro studies using a pulsatile mock circulation loop to confirm the impeller's top contact position and the swinging motion produced by the pulsation. Eleven in vivo BVAD studies confirmed that this swinging motion eliminated blood clot formation. Twenty-one pumps im-planted for up to three months did not reveal any thrombosis in the pumps or downstream organs. One exception was a right pump which was exposed to severe low flow due to the kinking of the outflow graft by the accidental pulling of the flow meter cable. Three ninety-day BVAD studies were achieved without thrombus formation.

  20. The Effect of Geometry on the Efficiency and Hemolysis of Centrifugal Implantable Blood Pumps.

    PubMed

    Mozafari, Sahand; Rezaienia, Mohammad A; Paul, Gordon M; Rothman, Martin T; Wen, Pihua; Korakianitis, Theodosios

    The application of centrifugal pumps as heart assist devices imposes design limitations on the impeller geometry. Geometry and operating parameters will affect the performance and the hemocompatibility of the device. Among all the parameters affecting the hemocompatibility, pressure, rotational speed, blade numbers, angle, and width have significant impact on the blood trauma. These parameters directly (pressure, speed) and indirectly (geometry) affect the efficiency of the pump as well. This study describes the experimental investigation on geometric parameters and their effect on the performance of small centrifugal pumps suitable for Mechanical Circulatory Support (MCS) devices. Experimental and numerical techniques were implemented to analyze the performance of 15 centrifugal impellers with different characteristics. The effect of each parameter on the pump performance and hemolysis was studied by calculating the normalized index of hemolysis (NIH) and the shear stress induced in each pump. The results show five and six blades, 15-35° outlet angle, and the lowest outlet width that meets the required pressure rise are optimum values for an efficient hemocompatible pump.

  1. Study of a centrifugal blood pump in a mock loop system.

    PubMed

    Uebelhart, Beatriz; da Silva, Bruno Utiyama; Fonseca, Jeison; Bock, Eduardo; Leme, Juliana; da Silva, Cibele; Leão, Tarcísio; Andrade, Aron

    2013-11-01

    An implantable centrifugal blood pump (ICBP) is being developed to be used as a ventricular assist device (VAD) in patients with severe cardiovascular diseases. The ICBP system is composed of a centrifugal pump, a motor, a controller, and a power supply. The electricity source provides power to the controller and to a motor that moves the pump's rotor through magnetic coupling. The centrifugal pump is composed of four parts: external conical house, external base, impeller, and impeller base. The rotor is supported by a pivot bearing system, and its impeller base is responsible for sheltering four permanent magnets. A hybrid cardiovascular simulator (HCS) was used to evaluate the ICBP's performance. A heart failure (HF) (when the heart increases beat frequency to compensate for decrease in blood flow) was simulated in the HCS. The main objective of this work is to analyze changes in physiological parameters such as cardiac output, blood pressure, and heart rate in three situations: healthy heart, HF, and HF with left circulatory assistance by ICBP. The results showed that parameters such as aortic pressure and cardiac output affected by the HF situation returned to normal values when the ICBP was connected to the HCS. In conclusion, the test results showed satisfactory performance for the ICBP as a VAD.

  2. Design and evaluation of a single-pivot supported centrifugal blood pump.

    PubMed

    Yoshino, M; Uemura, M; Takahashi, K; Watanabe, N; Hoshi, H; Ohuchi, K; Nakamura, M; Fujita, H; Sakamoto, T; Takatani, S

    2001-09-01

    In order to develop a centrifugal blood pump that meets the requirements of a long-term, implantable circulatory support device, in this study a single-pivot bearing supported centrifugal blood pump was designed to evaluate its basic performance. The single-pivot structure consisted of a ceramic ball male pivot mounted on the bottom surface of the impeller and a polyethylene female pivot incorporated in the bottom pump casing. The follower magnet mounted inside the impeller was magnetically coupled to the driver magnet mounted on the shaft of the direct current brushless motor. As the motor rotated, the impeller rotated supported entirely by a single-pivot bearing system. The static pump performance obtained in the mock circulatory loop revealed an acceptable performance as a left ventricular assist device in terms of flow and head pressure. The pump flow of 5 L/min against the head pressure of 100 mm Hg was obtained at rotational speeds of 2,000 to 2,200 rpm. The maximum pump flow was 9 L/min with 2,200 rpm. The maximum electrical-to-hydraulic power conversion efficiency was around 14% at pump flows of 4 to 5 L/min. The stability of the impeller was demonstrated at the pump rpm higher than 1,400 with a single-pivot bearing without an additional support at its top. The single-pivot supported centrifugal pump can provide adequate flow and pressure as a ventricular assist device, but its mechanical stability and hemolytic as well as thrombotic performances must be tested prior to clinical use.

  3. A new design for a compact centrifugal blood pump with a magnetically levitated rotor.

    PubMed

    Asama, Junichi; Shinshi, Tadahiko; Hoshi, Hideo; Takatani, Setsuo; Shimokohbe, Akira

    2004-01-01

    A compact centrifugal blood pump has been developed using a radial magnetic bearing with a two-degree of freedom active control. The proposed magnetic bearing exhibits high stiffness, even in passively controlled directions, and low power consumption because a permanent magnet, incorporated with the rotor, suspends its weight. The rotor is driven by a Lorentz force type of built-in motor, avoiding mechanical friction and material wear. The built-in motor is designed to generate only rotational torque, without radial and axial attractive forces on the rotor, leading to low power consumption by the magnetic bearing. The fabricated centrifugal pump measured 65 mm in diameter and 45 mm in height and weighed 0.36 kg. In the closed loop circuit filled with water, the pump provided a flow rate of 4.5 L/min at 2,400 rpm against a pressure head of 100 mm Hg. Total power consumption at that point was 18 W, including 2 W required for magnetic levitation, with a total efficiency of 5.7%. The experimental results showed that the design of the compact magnetic bearing was feasible and effective for use in a centrifugal blood pump.

  4. Hemolysis and heat generation in six different types of centrifugal blood pumps.

    PubMed

    Araki, K; Taenaka, Y; Masuzawa, T; Tatsumi, E; Wakisaka, Y; Watari, M; Nakatani, T; Akagi, H; Baba, Y; Anai, H

    1995-09-01

    What the most causative factor affecting hemolysis is still controversial. To resolve this problem, we investigated the relationship between hemolysis and heat generation in six types of centrifugal blood pumps (Bio-Pump, Delphin, Capiox, Nikkiso, Isoflow, and Toyobo). The analyzed parameters were index of hemolysis in fresh goat blood, pumping performance, and heat generation in a thermally isolated mock circuit. These parameters were analyzed at a flow rate of 5 L/min by changing the pressure head (100 mm Hg and 500 mm Hg). At 500 mm Hg of pressure head, the Bio-Pump needed the highest rotation number and showed the highest hemolytic rate and heat generation. The index of hemolysis is well correlated to heat generation (r2 = 0.721). Heat may originate from the motor by conduction, hydraulic energy loss, and mechanical friction between the shaft and seal. We strongly suspect that hemolysis was caused by a factor such as mechanical friction which generates heat locally.

  5. Hemolysis in different centrifugal pumps.

    PubMed

    Kawahito, K; Nosé, Y

    1997-04-01

    Different types of centrifugal pumps cause different amounts of hemolysis based on shear stress and blood exposure time. However, the hemolytic characteristics of centrifugal pumps in each clinical condition are not always clear. We compared the hemolytic characteristics of one cone-type centrifugal pump (Medtronic BioMedicus BP-80) and 2 impeller-type centrifugal pumps (Nikkiso HMS-12 and Terumo Capiox) under experimental conditions simulating their use in cardiopulmonary bypass (CPB), extracorporeal membrane oxygenation (ECMO), and percutaneous cardiopulmonary support (PCPS) as well as their use as left ventricular assist devices (LVADs). The normalized indexes of hemolysis (NIHs; grams free plasma hemoglobin per 100 L blood pumped) during use as LVADs were not significantly different among the 3 pumps. The BP-80 pump produced almost 3-fold more hemolysis than the HMS-12 and Capiox pumps during CPB, 3- to 4-fold more hemolysis during ECMO, and 5.5-fold more hemolysis during PCPS. The 2 impeller-type centrifugal pumps will therefore cause less hemolysis under high flow, high pressure difference (as in CPB) and low flow, high pressure difference (as in ECMO and PCPS) conditions than the cone-type pump.

  6. Numerical study of a bio-centrifugal blood pump with straight impeller blade profiles.

    PubMed

    Song, Guoliang; Chua, Leok Poh; Lim, Tau Meng

    2010-02-01

    Computational fluid dynamic simulations of the flow in the Kyoto-NTN (Kyoto University, Kyoto, Japan) magnetically suspended centrifugal blood pump with a 16-straight-bladed impeller were performed in the present study. The flow in the pump was assumed as unsteady and turbulent, and blood was treated as a Newtonian fluid. At the impeller rotating speed of 2000 rpm and flow rate of 5 L/min, the pump produces a pressure head of 113.5 mm Hg according to the simulation. It was found that the double volute of the pump has caused symmetrical pressure distribution in the volute passages and subsequently caused symmetrical flow patterns in the blade channels. Due to the tangentially increasing pressure in the volute passages, the flow through the blade channels initially increases at the low-pressure region and then decreases due to the increased pressure. The reverse flow and vortices have been identified in the impeller blade channels. The high shear stress of the flow in the pump mainly occurred at the inlet and outlet of the blade channels, the beginning of the volute passages and the regions around the tips of the cutwater and splitter plate. Higher shear stress is obtained when the tips of the cutwater and splitter plate are located at the impeller blade trailing edges than when they are located at the middle of the impeller blade channel. It was found that the blood damage index assessed based on the blood corpuscle path tracing of the present pump was about 0.94%, which has the same order of magnitude as those of the clinical centrifugal pumps reported in the literature.

  7. Centrifugal main fuel pump

    SciTech Connect

    Cole, E.F.

    1986-08-26

    For a gas turbine power plant having a fuel supply and a fuel metering valve and variable geometry for the power plant including servo actuating mechanisms for the fuel metering valve and variable geometry, a fuel pumping system, is described to supply pressurized fuel for the servo actuating mechanisms and for the engine working fluid medium. The pumping system includes a centrifugal pump solely supplying the fuel to the fuel metering valve to be delivered to the power plant for its working fluid medium, a positive displacement pump in parallel with the centrifugal pump and solely to supply pressurized fuel to the servo actuating mechanisms for the fuel metering valve and for the variable geometry, and a boost pump means disposed in serial relationship with the positive displacement pump and the centrifugal pump for augmenting the pressure supplied by the positive displacement pump and the centrifugal pump during predetermined operating conditions of the power plant. The combined boost pump and centrifugal pump capability is sufficient to satisfy the vapor to liquid ratio requirements of the power during its entire operating envelope.

  8. An implantable centrifugal blood pump with a recirculating purge system (Cool-Seal system).

    PubMed

    Yamazaki, K; Litwak, P; Tagusari, O; Mori, T; Kono, K; Kameneva, M; Watach, M; Gordon, L; Miyagishima, M; Tomioka, J; Umezu, M; Outa, E; Antaki, J F; Kormos, R L; Koyanagi, H; Griffith, B P

    1998-06-01

    A compact centrifugal blood pump has been developed as an implantable left ventricular assist system. The impeller diameter is 40 mm, and pump dimensions are 55 x 64 mm. This first prototype, fabricated from titanium alloy, resulted in a pump weight of 400 g including a brushless DC motor. The weight of a second prototype pump was reduced to 280 g. The entire blood contacting surface is coated with diamond like carbon (DLC) to improve blood compatibility. Flow rates of over 7 L/min against 100 mm Hg pressure at 2,500 rpm with 9 W total power consumption have been measured. A newly designed mechanical seal with a recirculating purge system (Cool-Seal) is used for the shaft seal. In this seal system, the seal temperature is kept under 40 degrees C to prevent heat denaturation of blood proteins. Purge fluid also cools the pump motor coil and journal bearing. Purge fluid is continuously purified and sterilized by an ultrafiltration unit which is incorporated in the paracorporeal drive console. In vitro experiments with bovine blood demonstrated an acceptably low hemolysis rate (normalized index of hemolysis = 0.005 +/- 0.002 g/100 L). In vivo experiments are currently ongoing using calves. Via left thoracotomy, left ventricular (LV) apex descending aorta bypass was performed utilizing an expanded polytetrafluoroethylene (ePTFE) vascular graft with the pump placed in the left thoracic cavity. In 2 in vivo experiments, the pump flow rate was maintained at 5-9 L/min, and pump power consumption remained stable at 9-10 W. All plasma free Hb levels were measured at less than 15 mg/dl. The seal system has demonstrated good seal capability with negligible purge fluid consumption (<0.5 ml/day). In both calves, the pumps demonstrated trouble free continuous function over 6 month (200 days and 222 days).

  9. Plasma Skimming in a Spiral Groove Bearing of a Centrifugal Blood Pump.

    PubMed

    Murashige, Tomotaka; Sakota, Daisuke; Kosaka, Ryo; Nishida, Masahiro; Kawaguchi, Yasuo; Yamane, Takashi; Maruyama, Osamu

    2016-09-01

    Plasma skimming is a phenomenon in which discharge hematocrit is lower than feed hematocrit in microvessels. Plasma skimming has been investigated at a bearing gap in a spiral groove bearing (SGB), as this has the potential to prevent hemolysis in the SGB of a blood pump. However, it is not clear whether plasma skimming occurs in a blood pump with the SGB, because the hematocrit has not been obtained. The purpose of this study is to verify plasma skimming in an SGB of a centrifugal blood pump by developing a hematocrit measurement method in an SGB. Erythrocyte observation using a high-speed microscope and a bearing gap measurement using a laser confocal displacement meter was performed five times. In these tests, bovine blood as a working fluid was diluted with autologous plasma to adjust the hematocrit to 1.0%. A resistor was adjusted to achieve a pressure head of 100 mm Hg and a flow rate of 5.0 L/min at a rotational speed of 2800 rpm. Hematocrit on the ridge region in the SGB was measured using an image analysis based on motion image of erythrocytes, mean corpuscular volume, the measured bearing gap, and a cross-sectional area of erythrocyte. Mean hematocrit on the ridge region in the SGB was linearly reduced from 0.97 to 0.07% with the decreasing mean bearing gap from 38 to 21 μm when the rotational speed was changed from 2250 to 3000 rpm. A maximum plasma skimming efficiency of 93% was obtained with a gap of 21 μm. In conclusion, we succeeded in measuring the hematocrit on the ridge region in the SGB of the blood pump. Hematocrit decreased on the ridge region in the SGB and plasma skimming occurred with a bearing gap of less than 30 μm in the hydrodynamically levitated centrifugal blood pump.

  10. Development of a Compact Maglev Centrifugal Blood Pump Enclosed in a Titanium Housing

    NASA Astrophysics Data System (ADS)

    Pai, Chi Nan; Shinshi, Tadahiko; Asama, Junichi; Takatani, Setsuo; Shimokohbe, Akira

    A compact centrifugal blood pump consisting of a controlled two-degrees-of-freedom radial magnetic bearing and a brushless DC motor enclosed in a titanium housing has been developed for use as an implantable ventricular assist device. The magnetic bearing also supports axial and angular motions of the impeller via a magnetic coupling. The top housing is made of pure titanium, while the impeller and the stator are coated with pure titanium and Ti-6Al-7Nb, respectively, to improve the biocompatibility of the pump. The combination of pure titanium and titanium alloy was chosen because of the sensitivity of eddy current type displacement sensors through the intervening conducting wall. The dimensions of the pump are 69.0 mm in diameter and 28.5 mm in height. During a pump performance test, axial shifting of the impeller due to hydraulic forces led to variations in the rotational positioning signal, causing loss of control of the rotational speed. This problem was solved by conditioning the rotational positioning signal. With a flow rate of 5 l/min against a head pressure of 100 mmHg, the power consumption and efficiency of the pump were 5.5 W and 20%, respectively. Furthermore, the hemolysis of the blood pump was 43.6% lower when compared to that of a commercially available pump.

  11. A compact centrifugal blood pump for extracorporeal circulation: design and performance.

    PubMed

    Tanaka, S; Yamamoto, S; Yamakoshi, K; Kamiya, A

    1987-08-01

    A new compact centrifugal blood pump driven by a miniature DC servomotor has been designed for use for short-term extra corporeal and cardiac-assisted circulation. The impeller of the pump was connected directly to the motor by using a simple-gear coupling. The shaft for the impeller was sealed from blood by both a V-ring and a seal bearing. Either pulsatile or nonpusatile flow was produced by controlling the current supply to the motor. The pump characteristics and the degree of hemolysis were evaluated with regard to the configuration of the impeller with a 38-mm outer diameter in vitro tests; the impeller having the blade angles at the inlet of 20 deg and at the outlet of 50 deg was the most appropriate as a blood pump. The performance in an operation, hemolysis and thrombus formation in the pump were assessed by a left ventricular bypass experiment in dogs. It was suggested by this study that this prototype pump appears promising for use not only in animal experiments but also in clinical application.

  12. Centrifugal blood pump for temporary ventricular assist devices with low priming and ceramic bearings.

    PubMed

    Leme, Juliana; da Silva, Cibele; Fonseca, Jeison; da Silva, Bruno Utiyama; Uebelhart, Beatriz; Biscegli, José F; Andrade, Aron

    2013-11-01

    A new model of centrifugal blood pump for temporary ventricular assist devices has been developed and evaluated. The design of the device is based on centrifugal pumping principles and the usage of ceramic bearings, resulting in a pump with reduced priming (35 ± 2 mL) that can be applied for up to 30 days. Computational fluid dynamic (CFD) analysis is an efficient tool to optimize flow path geometry, maximize hydraulic performance, and minimize shear stress, consequently decreasing hemolysis. Initial studies were conducted by analyzing flow behavior with different impellers, aiming to determine the best impeller design. After CFD studies, rapid prototyping technology was used for production of pump prototypes with three different impellers. In vitro experiments were performed with those prototypes, using a mock loop system composed of Tygon tubes, oxygenator, digital flow meter, pressure monitor, electronic driver, and adjustable clamp for flow control, filled with a solution (1/3 water, 1/3 glycerin, 1/3 alcohol) simulating blood viscosity and density. Flow-versus-pressure curves were obtained for rotational speeds of 1000, 1500, 2000, 2500, and 3000 rpm. As the next step, the CFD analysis and hydrodynamic performance results will be compared with the results of flow visualization studies and hemolysis tests.

  13. A new model of centrifugal blood pump for cardiopulmonary bypass: design improvement, performance, and hemolysis tests.

    PubMed

    Leme, Juliana; Fonseca, Jeison; Bock, Eduardo; da Silva, Cibele; da Silva, Bruno Utiyama; Dos Santos, Alex Eugênio; Dinkhuysen, Jarbas; Andrade, Aron; Biscegli, José F

    2011-05-01

    A new model of blood pump for cardiopulmonary bypass (CPB) application has been developed and evaluated in our laboratories. Inside the pump housing is a spiral impeller that is conically shaped and has threads on its surface. Worm gears provide an axial motion of the blood column. Rotational motion of the conical shape generates a centrifugal pumping effect and improves pumping performance. One annular magnet with six poles is inside the impeller, providing magnetic coupling to a brushless direct current motor. In order to study the pumping performance, a mock loop system was assembled. Mock loop was composed of Tygon tubes (Saint-Gobain Corporation, Courbevoie, France), oxygenator, digital flowmeter, pressure monitor, electronic driver, and adjustable clamp for flow control. Experiments were performed on six prototypes with small differences in their design. Each prototype was tested and flow and pressure data were obtained for rotational speed of 1000, 1500, 2000, 2500, and 3000 rpm. Hemolysis was studied using pumps with different internal gap sizes (1.35, 1.45, 1.55, and 1.7 mm). Hemolysis tests simulated CPB application with flow rate of 5 L/min against total pressure head of 350 mm Hg. The results from six prototypes were satisfactory, compared to the results from the literature. However, prototype #6 showed the best results. Best hemolysis results were observed with a gap of 1.45 mm, and showed a normalized index of hemolysis of 0.013 g/100 L. When combined, axial and centrifugal pumping principles produce better hydrodynamic performance without increasing hemolysis.

  14. Estimating mechanical blood trauma in a centrifugal blood pump: laser Doppler anemometer measurements of the mean velocity field.

    PubMed

    Pinotti, M; Paone, N

    1996-06-01

    A laser Doppler anemometer (LDA) was used to obtain the mean velocity and the Reynolds stress fields in the inner channels of a well-known centrifugal vaneless pump (Bio-pump). Effects of the excessive flow resistance against which an occlusive pump operates in some surgical situations, such as cardiopulmonary bypass, are illustrated. The velocity vector field obtained from LDA measurements reveals that the constraint-forced vortex provides pumping action in a restricted area in the core of the pump. In such situations, recirculating zones dominate the flow and consequently increase the damage to blood cells and raise the risk of thrombus formation in the device. Reynolds normal and shear stress fields were obtained in the entry flow for the channel formed by two rotating cones to illustrate the effects of flow disturbances on the potential for blood cell damage.

  15. Hemolytic evaluation using polyurethane microcapsule suspensions in circulatory support devices: normalized index of hemolysis comparisons of commercial centrifugal blood pumps.

    PubMed

    Maruyama, Osamu; Yamaguchi, Katsuhiro; Nishida, Masahiro; Onoguchi, Tomio; Tsutsui, Tatsuo; Jikuya, Tomoaki; Yamane, Takashi

    2008-02-01

    We have been developing some types of microcapsule suspensions with polyurethane membranes to evaluate the absolute hemolytic characteristics of the centrifugal blood pumps used in circulatory support devices such as artificial hearts. In order to facilitate/realize hemolysis testing on centrifugal blood pumps that have hemolysis levels as low as those of commercial centrifugal blood pumps, we eliminated capsules with diameters less than 72.2 microm, amounting to 15.4% of all capsules in the conventional suspension (crude suspension [CS]), and adjusted the capsule volume ratio to correspond to a hematocrit of 40%. In this way we succeeded in enhancing the sensitivity of the suspension to microcapsule destruction 61 fold. We used this new suspension (fine suspension [FS]) to perform hemolysis tests on four types of commercial pump with mock circulation systems. Under conditions of 500 mm Hg and 11.2 L/min, we successfully determined the hemolytic characteristics (normalized index of hemolysis [NIH]) of some of the centrifugal blood pumps; the results showed some correlation with those of hemolysis tests on bovine blood and suggest that microcapsule suspensions with polyurethane membranes are useful as standard test solutions for the absolute evaluation of centrifugal blood pumps.

  16. Current status of the gyro centrifugal blood pump--development of the permanently implantable centrifugal blood pump as a biventricular assist device (NEDO project).

    PubMed

    Nosé, Yukihiko; Furukawa, Kojiro

    2004-10-01

    The New Energy and Industrial Technology Development Organization (NEDO) project was started in 1995. The goal is the development of a multipurpose, totally implantable biventricular assist device (BVAD) that can be used for any patient who suffers from severe heart failure. Our C1E3 (two-week pump) centrifugal pump, called the Gyro pump, has three design characteristics: a magnetic coupling and double pivot bearing system, an eccentric inlet port, and secondary vanes on the bottom of the impeller. The pump was miniaturized. The C1E3 evolved into the NEDO PI-601, a totally implantable centrifugal pump for BVAD. The current NEDO PI-710 pump (five-year pump) system includes a centrifugal pump with pivot bearings, a hydraulically-levitated impeller, an rpm-controlled miniaturized actuator (all-in-one actuator plus controller), an emergency clamp on the left outflow, and a Frank-Starling-type flow control. The final mass production model is now finalized, and the final animal study and two-year endurance studies are ongoing.

  17. Fault-tolerant strategies for an implantable centrifugal blood pump using a radially controlled magnetic bearing.

    PubMed

    Pai, Chi Nan; Shinshi, Tadahiko

    2011-10-01

    In our laboratory, an implantable centrifugal blood pump (CBP) with a two degrees-of-freedom radially controlled magnetic bearing (MB) to support the impeller without contact has been developed to assist the pumping function of the weakened heart ventricle. In order to maintain the function of the CBP after damage to the electromagnets (EMs) of the MB, fault-tolerant strategies for the CBP are proposed in this study. Using a redundant MB design, magnetic levitation of the impeller was maintained with damage to up to two out of a total of four EMs of the MB; with damage to three EMs, contact-free support of the impeller was achieved using hydrodynamic and electromagnetic forces; and with damage to all four EMs, the pump operating point, of 5 l/min against 100 mmHg, was achieved using the motor for rotation of the impeller, with contact between the impeller and the stator.

  18. PIV measurements of flow in a centrifugal blood pump: time-varying flow.

    PubMed

    Day, Steven W; McDaniel, James C

    2005-04-01

    Measurements of the time-varying flow in a centrifugal blood pump operating as a left ventricular assist device (LVAD) are presented. This includes changes in both the pump flow rate as a function of the left ventricle contraction and the interaction of the rotating impeller and fixed exit volute. When operating with a pulsing ventricle, the flow rate through the LVAD varies from 0-11 L/min during each cycle of the heartbeat. Phase-averaged measurements of mean velocity and some turbulence statistics within several regions of the pump, including the inlet, blade passage, exit volute, and diffuser, are reported at 20 phases of the cardiac cycle. The transient flow fields are compared to the constant flow rate condition that was reported previously in order to investigate the transient effects within the pump. It is shown that the quasi-steady assumption is a fair treatment of the time varying flow field in all regions of this representative pump, which greatly simplifies the comprehension and modeling of this flow field. The measurements are further interpreted to identify the effects that the transient nature of the flow field will have on blood damage. Although regions of recirculation and stagnant flow exist at some phases of the cardiac cycle, there is no location where flow is stagnant during the entire heartbeat.

  19. Testing of a centrifugal blood pump with a high efficiency hybrid magnetic bearing.

    PubMed

    Locke, Dennis H; Swanson, Erik S; Walton, James F; Willis, John P; Heshmat, Hooshang

    2003-01-01

    The purpose of this article is to present test results for a second generation, high efficiency, nonpulsatile centrifugal blood pump that is being developed for use as a left ventricular assist device (LVAD). The LVAD pump uses a hybrid passive-active magnetic bearing support system that exhibits extremely low power loss, low vibration, and high reliability under transient conditions and varying pump orientations. A unique feature of the second generation design configuration is the very simple and direct flow path for both main and washing blood flows. The pump was tested in both vertical and horizontal orientations using a standard flow loop to demonstrate the performance and durability of the second generation LVAD. Steady state and transient orientation pump operating characteristics including pressure, flow, speed, temperatures, vibration, and rotor orientation were measured. During the tests, pump performance was mapped at several operating conditions including points above and below the nominal design of 5 L/min at 100 mm Hg pressure rise. Flow rates from 2 to 7 L/min and pressure rises from 50 to 150 mm Hg were measured. Pump speeds were varied during these tests from 2,500 to 3,500 rpm. The nominal design flow of 5 L/min at 100 mm Hg pressure rise was successfully achieved at the design speed of 3,000 rpm. After LVAD performance testing, both 28 day continuous duty and 5 day transient orientation durability tests were completed without incident. A hydrodynamic backup bearing design feasibility study was also conducted. Results from this design study indicate that an integral hydrodynamic backup bearing may be readily incorporated into the second generation LVAD and other magnetically levitated pump rotors.

  20. Microhaemodynamics within the blade tip clearance of a centrifugal turbodynamic blood pump.

    PubMed

    Antaki, J F; Diao, C-G; Shu, F-J; Wu, J-C; Zhao, R; Kameneva, M V

    2008-05-01

    A persistent challenge facing the quantitative design of turbodynamic blood pumps is the great disparity of spatial scales between the primary and auxiliary flow paths. Fluid passages within journals and adjacent to the blade tips are often on the scale of several blood cells, confounding the application of macroscopic continuum models. Yet, precisely in these regions there exists the highest shear stress, which is most likely to cause cellular trauma. This disparity has motivated these microscopic studies to visualize the kinematics of the blood cells within the small clearances of a miniature turbodynamic blood pump. A transparent model of a miniature centrifugal pump having an adjustable tip clearance (50-200 microm) was prepared for direct optical visualization of the region between the impeller blade tip and the stationary housing. Synchronized images of the blood cells were obtained by a microscopic visualization system, consisting of an inverted microscope fitted with long-working-distance objective lens (40x), mercury lamp, and high-resolution charge-coupled device camera electronically triggered by the rotation of the impeller. Experiments with 7 microm fluorescent particles revealed the influence of the gap dimension on the trajectory across the blade thickness. The lateral component of velocity (perpendicular to the blade) was dramatically enhanced in the 50 microm gap compared with the 200 microm gap, thereby reducing the exposure time. Studies with diluted bovine blood (Ht = 0.5 per cent) showed that the concentration of cells traversing the gap is also reduced dramatically (30 per cent) as the blade tip clearance is reduced from 200 microm to 50 microm. These results motivate further investigation into the microfluidic phenomena responsible for cellular trauma within turbodynamic blood pumps.

  1. PIV measurements of flow in a centrifugal blood pump: steady flow.

    PubMed

    Day, Steven W; McDaniel, James C

    2005-04-01

    Magnetically suspended left ventricular assist devices have only one moving part, the impeller. The impeller has absolutely no contact with any of the fixed parts, thus greatly reducing the regions of stagnant or high shear stress that surround a mechanical or fluid bearing. Measurements of the mean flow patterns as well as viscous and turbulent stresses were made in a shaft-driven prototype of a magnetically suspended centrifugal blood pump at several constant flow rates (3-9 L/min) using particle image velocimetry (PIV). The chosen range of flow rates is representative of the range over which the pump may operate while implanted. Measurements on a three-dimensional measurement grid within several regions of the pump, including the inlet, blade passage, exit volute, and diffuser are reported. The measurements are used to identify regions of potential blood damage due to high shear stress and/or stagnation of the blood, both of which have been associated with blood damage within artificial heart valves and diaphragm-type pumps. Levels of turbulence intensity and Reynolds stresses that are comparable to those in artificial heart valves are reported. At the design flow rate (6 L/min), the flow is generally well behaved (no recirculation or stagnant flow) and stress levels are below levels that would be expected to contribute to hemolysis or thrombosis. The flow at both high (9 L/min) and low (3 L/min) flow rates introduces anomalies into the flow, such as recirculation, stagnation, and high stress regions. Levels of viscous and Reynolds shear stresses everywhere within the pump are below reported threshold values for damage to red cells over the entire range of flow rates investigated; however, at both high and low flow rate conditions, the flow field may promote activation of the clotting cascade due to regions of elevated shear stress adjacent to separated or stagnant flow.

  2. Centrifugal pump fuel system

    SciTech Connect

    McGlone, M.E.; Larkins, L.J.; Johnson, R.O.; Moeller, K.A.

    1993-06-22

    A centrifugal pump fuel system for an engine driven fuel pump for an aircraft gas turbine engine is described comprising: a centrifugal pump having at constant speed rising head/flow characteristic at low flows; a plumbing system receiving flow from the pump, and having at least one control valve located down stream of and defining a discrete volume of the plumbing system; a plumbing resonant frequency defined by the discrete volume, the geometry of the plumbing system, and the bulk modulus of the fuel; a pressure difference regulating valve located adjacent to the discharge of the pump, up stream of the vast majority of the discrete volume; and the frequency response of the regulating valve being significantly less than the frequency response of the plumbing system such that the response of the regulating valve is attenuated at the resonant frequency of the plumbing system.

  3. Dynamic characteristics of a magnetically levitated impeller in a centrifugal blood pump.

    PubMed

    Asama, Junichi; Shinshi, Tadahiko; Hoshi, Hideo; Takatani, Setsuo; Shimokohbe, Akira

    2007-04-01

    Centrifugal blood pumps that employ hybrid active/passive magnetic bearings to support noncontact impellers have been developed in order to reduce bearing wear, pump size, the power consumption of the active magnetic bearing, and blood trauma. However, estimates made at the design stage of the vibration of the impeller in the direction of passive suspension during pump operation were inaccurate, because the influence of both the pumping fluid and the rotation of the impeller on the dynamic characteristics was not fully recognized. The purpose of this study is to investigate the dynamic characteristics in a fluid of a magnetically levitated rotating impeller by measuring both the frequency response to sinusoidal excitation of the housing over a wide frequency range and the displacement due to input of a pulsatile flow during left ventricular (LV) assist. The excitation tests were conducted under conditions in which the impeller was levitated in either air or water, and with or without rotation. The experimental and analytical results indicate that vibration of the impeller due to the external force in water was decreased, compared with that in air due to the hydraulic force of water. The axial resonant frequency rose quadratically with rotational speed, and the tilt mode had two resonant frequencies while rotating due to the gyroscopic effect. With the pump inserted into a mock systemic circulatory loop, the dynamic stability of the impeller when pulsatile pressure was applied during LV assist was verified experimentally. The amplitudes of vibration in response to the pulsatile flow in the passively constrained directions were considerably smaller in size than the dimensions of initial gaps between the impeller and the pump housing.

  4. Fluid dynamic design for low hemolysis in a hydrodynamically levitated centrifugal blood pump.

    PubMed

    Murashige, Tomotaka; Kosaka, Ryo; Nishida, Masahiro; Maruyama, Osamu; Yamane, Takashi; Kuwana, Katsuyuki; Kawaguchi, Yasuo

    2013-01-01

    We have developed a hydrodynamically levitated centrifugal blood pump for extracorporeal circulatory support as a bridge to decision pump. The impeller is levitated using hydrodynamic bearings without any complicated control circuit or displacement sensor. However, the effect of the outer circumferential velocity and the bearing area on the hemolytic property has not been clarified, even if the bearing gap is same size. The purpose of this study is to experimentally evaluate the effect of the outer circumferential velocity and the bearing area in the bearing gaps on the hemolytic property in a hydrodynamically levitated centrifugal blood pump. We prepared three models for testing. These models have the same bearing gap size by adjusting the impeller levitation position. However, the outer circumferential velocity of the impeller and the bearing area in the minimum bearing gaps are different. The outer circumferential velocity of the impeller and the bearing area were assumed to be related to the maximum shear rate and the exposure time. For the evaluation, we conducted an impeller levitation performance test and an in vitro hemolysis test. As a result, the normalized index of hemolysis (NIH) was reduced from 0.084 g/100 L to 0.040 g/100 L corresponding to a reduction in the outer circumferential velocity and a reduction in the bearing area, even if the minimum bearing gaps were same size. We confirmed that, even if the bearing gap was same size under the stably levitated condition, the outer circumferential velocity and the bearing area should be decreased in order to improve the hemolytic property.

  5. A compact highly efficient and low hemolytic centrifugal blood pump with a magnetically levitated impeller.

    PubMed

    Asama, Junichi; Shinshi, Tadahiko; Hoshi, Hideo; Takatani, Setsuo; Shimokohbe, Akira

    2006-03-01

    A magnetically levitated (maglev) centrifugal blood pump (CBP), intended for use as a ventricular assist device, needs to be highly durable and reliable for long-term use without any mechanical failure. Furthermore, maglev CBPs should be small enough to be implanted into patients of various size and weight. We have developed a compact maglev CBP employing a two-degree-of-freedom controlled magnetic bearing, with a magnetically suspended impeller directly driven by an internal brushless direct current (DC) motor. The magnetic bearing actively controls the radial motion of the impeller and passively supports axial and angular motions using a permanent magnet embedded in the impeller. The overall dimensions of the maglev CBP are 65 mm in diameter and 40 mm in height. The total power consumption and pump efficiency for pumping 6 L/min against a head pressure of 105 mm Hg were 6.5 W and 21%, respectively. To evaluate the characteristics of the maglev CBP when subjected to a disturbance, excitation of the base, simulating the movement of the patient in various directions, and the sudden interception of the outlet tube connected with the pump in a mock circulatory loop, simulating an unexpected kink and emergent clamp during a heart surgery, were tested by monitoring the five-degree-of-freedom motion of the impeller. Furthermore, the hemolytic characteristics of the maglev CBP were compared with those of the Medtronic Biomedicus BPX-80, which demonstrated the superiority of the maglev CBP.

  6. An investigational study of minimum rotational pump speed to avoid retrograde flow in three centrifugal blood pumps in a pediatric extracorporeal life support model.

    PubMed

    Clark, Joseph B; Guan, Yulong; McCoach, Robert; Kunselman, Allen R; Myers, John L; Undar, Akif

    2011-05-01

    During extracorporeal life support with centrifugal blood pumps, retrograde pump flow may occur when the pump revolutions decrease below a critical value determined by the circuit resistance and the characteristics of the pump. We created a laboratory model to evaluate the occurrence of retrograde flow in each of three centrifugal blood pumps: the Rotaflow, the CentriMag, and the Bio-Medicus BP-50. At simulated patient pressures of 60, 80, and 100 mmHg, each pump was evaluated at speeds from 1000 to 2200 rpm and flow rates were measured. Retrograde flow occurred at low revolution speeds in all three centrifugal pumps. The Bio-Medicus pump was the least likely to demonstrate retrograde flow at low speeds, followed by the Rotaflow pump. The CentriMag pump showed the earliest transition to retrograde flow, as well as the highest degree of retrograde flow. At every pump speed evaluated, the Bio-Medicus pump delivered the highest antegrade flow and the CentriMag pump delivered the least.

  7. [Magnetic field numerical calculation and analysis for magnetic coupling of centrifugal blood pump for extracorporeal circulation].

    PubMed

    Hu, Zhaoyan; Lu, Lijun; Zhang, Tianyi; Chen, Zhenglong; Zhang, Tao

    2013-12-01

    This paper mainly studies the driving system of centrifugal blood pump for extracorporeal circulation, with the core being disc magnetic coupling. Structure parameters of disc magnetic coupling are related to the ability of transferring magnetic torque. Therefore, it is necessary to carry out disc magnetic coupling permanent magnet pole number (n), air gap length (L(g)), permanent magnet thickness (L(m)), permanent magnet body inside diameter (R(i)) and outside diameter (R(o)), etc. thoroughly. This paper adopts the three-dimensional static magnetic field edge element method of Ansys for numerical calculation, and analyses the relations of magnetic coupling each parameter to transmission magnetic torque. It provides a good theory basis and calculation method for further optimization of the disc magnetic coupling.

  8. The pivot wash in two impeller modes for the Baylor/Miwatec centrifugal blood pump.

    PubMed

    Yamane, Takashi; Kodama, Takayuki; Nishida, Masahiro; Maruyama, Osamu; Yamamoto, Yoshiro; Shinohara, Toshiyuki; Motomura, Tadashi; Nosé, Yukihiko

    2006-01-01

    A centrifugal blood pump with a double pivot impeller and an eccentric inlet port is being developed as an implantable artificial heart by the Baylor College of Medicine and Miwatec Co. Ltd. Flow visualization measurements were conducted to compare the flow around the pivot for two impeller operational modes: the top and the bottom contact modes. In the top contact mode, one-way flow in the pivot gap due to the eccentric vortex was observed, and sufficient wall shear rate to prevent thrombus formation was attained around the bottom pivot for over 1,400 rpm. Computational fluid dynamic analyses confirmed that the causes of the eccentric vortex were the inlet eccentricity and the pressure imbalance in the volute.

  9. Long-term ex vivo bovine experiments with the Gyro C1E3 centrifugal blood pump.

    PubMed

    Kawahito, Shinji; Maeda, Tomohiro; Motomura, Tadashi; Takano, Tamaki; Nonaka, Kenji; Linneweber, Joerg; Ichikawa, Seiji; Kawamura, Masaki; Glueck, Julie; Fujisawa, Akira; Makinouchi, Kenzo; Nosé, Yukihiko

    2003-01-01

    Centrifugal blood pumps are used widely for cardiopulmonary bypass, as ventricular assist devices, and for extracorporeal membrane oxygenation (ECMO). However, there is no centrifugal blood pump that is suitable for long-term ECMO. The authors developed the Gyro C1E3 centrifugal blood pump (Kyocera Corporation, Kyoto, Japan), which has superior antithrombogenic, antitraumatic, and hydraulic features in comparison with the conventional centrifugal blood pumps. Five ex vivo long-term durability tests of the Gyro C1E3 were performed using healthy miniature calves. The ECMO circuit was composed of a prototype hollow fiber silicone membrane oxygenator and a Gyro C1E3 pump. Venous blood was drained from the left jugular vein of a calf, passed through the oxygenator and infused into the left carotid artery using a Gyro C1E3. Ex vivo studies were performed from 7 to 15 days at a blood flow rate of 1 L/min. During this period, the Gyro C1E3 demonstrated a stable performance without exchanging the pump. Bleeding complications were the major reason for termination of each experiment. Rotational speed was maintained around 2,000 rpm. All five calves demonstrated neither abnormal signs nor abnormal blood examination data throughout the experiment. Neither clot nor thrombus formations were found during the necropsy in the cannula or pump nor were infarctions observed in any of the major organs. In conclusion, the Gyro C1E3 showed a stable and reliable performance during long-term ex vivo bovine experiments under the conditions tested.

  10. Improvement of hemolysis in a centrifugal blood pump with hydrodynamic bearings and semi-open impeller.

    PubMed

    Kosaka, Ryo; Yamane, Takashi; Maruyama, Osamu; Nishida, Masahiro; Yada, Toru; Saito, Sakae; Hirai, Shusaku

    2007-01-01

    We have developed a centrifugal blood pump with hydrodynamic bearings and semi-open impeller, and evaluated the levitation performance test and the hemolysis test. This pump is operated without any complicated control circuit and displacement-sensing module. The casing diameter is 74 mm and the height is 38 mm including flanges for volts. The weight is 251 g and the volume is 159 cm3. By changing the stator relative position against the rotor, the levitation characteristics of the impeller can be adjusted. The diameter of impeller is 36 mm and the height is 25 mm. The impeller is levitated by the thrust bearing of spiral groove type and a radial bearing of herringbone type. The pump performance was evaluated through the levitation performance test and the hemolysis test. As a result, the normalized index of hemolysis (NIH) was reduced from 0.72 g/100 L to 0.024 g/100 L corresponding to the changes of the groove direction of the hydrodynamic bearing and the expansion of the bearing gap. During these studies, we confirmed that the hemolytic property was improved by balancing the fluid dynamic force and the magnetic force.

  11. Quantification of the secondary flow in a radial coupled centrifugal blood pump based on particle tracking velocimetry.

    PubMed

    Watanabe, Nobuo; Masuda, Takaya; Iida, Tomoya; Kataoka, Hiroyuki; Fujimoto, Tetsuo; Takatani, Setsuo

    2005-01-01

    Secondary flow in the centrifugal blood pump helps to enhance the washout effect and to minimize thrombus formation. On the other hand, it has an adverse effect on pump efficiency. Excessive secondary flow may induce hemolytic effects. Understanding the secondary flow is thus important to the design of a compact, efficient, biocompatible blood pump. This study examined the secondary flow in a radial coupled centrifugal blood pump based on a simple particle tracking velocimetry (PTV) technique. A radial magnetically coupled centrifugal blood pump has a bell-shaped narrow clearance between the impeller inner radius and the pump casing. In order to vary the flow levels through the clearance area, clearance widths of 0.25 mm and 0.50 mm and impeller washout holes with diameters of 0 mm, 2.5 mm, and 4 mm were prepared. A high-speed video camera (2000 frames per second) was used to capture the particle images from which radial flow components were derived. The flow in the space behind the impeller was assumed to be laminar and Couette type. The larger the inner clearance or diameter of washout hole, the greater was the secondary flow rate. Without washout holes, the flow behind the impeller resulted in convection. The radial flow through the washout holes of the impeller was conserved in the radial as well as in the axial direction behind the impeller. The increase in the secondary flow reduced the net pump efficiency. Simple PTV was successful in quantifying the flow in the space behind the impeller. The results verified the hypothesis that the flow behind the impeller was theoretically Couette along the circumferential direction. The convection flow observed behind the impeller agreed with the reports of other researchers. Simple PTV was effective in understanding the fluid dynamics to help improve the compact, efficient, and biocompatible centrifugal blood pump for safe clinical applications.

  12. Left ventricular volume unloading with axial and centrifugal rotary blood pumps.

    PubMed

    Giridharan, Guruprasad A; Koenig, Steven C; Soucy, Kevin G; Choi, Young; Pirbodaghi, Tohid; Bartoli, Carlo R; Monreal, Gretel; Sobieski, Michael A; Schumer, Erin; Cheng, Allen; Slaughter, Mark S

    2015-01-01

    Axial (AX) and centrifugal (CFG) rotary blood pumps have gained clinical acceptance for the treatment of advanced heart failure. Differences between AX and CFG designs and mechanism of blood flow delivery may offer clinical advantages. In this study, pump characteristics, and acute physiologic responses during support with AX (HeartMate II) and CFG (HVAD) left ventricular assist devices (LVAD) were investigated in mock loop and chronic ischemic heart failure bovine models. In the mock loop model, pump performance was characterized over a range of pump speeds (HeartMate II: 7,000-11,000 rpm, HVAD: 2,000-3,600 rpm) and fluid viscosities (2.7 cP, 3.2 cP, 3.7 cP). In the ischemic heart failure bovine model, hemodynamics, echocardiography, and end-organ perfusion were investigated. CFG LVAD had a flatter HQ curve, required less power, and had a more linear flow estimation relation than AX LVAD. The flow estimation error for the AX LVAD (±0.9 L/min at 2.7 cP, ±0.7 L/min at 3.2 cP, ±0.8 L/min at 3.7 cP) was higher than the CFG LVAD (±0.5 L/min at 2.7 cP, ±0.2 L/min at 3.2 cP, ±0.5 L/min at 3.7 cP). No differences in acute hemodynamics, echocardiography, or end-organ perfusion between AX and CFG LVAD over a wide range of support were statistically discernible. These findings suggest no pronounced acute differences in LV volume unloading between AX and CFG LVAD.

  13. Development of the Baylor Gyro permanently implantable centrifugal blood pump as a biventricular assist device.

    PubMed

    Nonaka, K; Linneweber, J; Ichikawa, S; Yoshikawa, M; Kawahito, S; Mikami, M; Motomura, T; Ishitoya, H; Nishimura, I; Oestmann, D; Glueck, J; Schima, H; Wolner, E; Shinohara, T; Nosé, Y

    2001-09-01

    The Baylor Gyro permanently implantable centrifugal blood pump (Gyro PI pump) has been under development since 1995 at Baylor College of Medicine. Excellent results were achieved as a left ventricular assist device (LVAD) with survival up to 284 days. Based on these results, we are now focusing on the development of a biventricular assist device (BVAD) system, which requires 2 pumps to be implanted simultaneously in the preperitoneal space. Our hypothesis was that the Gyro PI pump would be an appropriate device for an implantable BVAD system. The Gyro PI 700 pump is fabricated from titanium alloy and has a 25 ml priming volume, pump weight of 204 g, height of 45 mm, and pump diameter of 65 mm. This pump can provide 5 L/min against 100 mm Hg at 2,000 rpm. In this study, 6 half-Dexter healthy calves have been used as the experimental model. The right pump was applied between the infundibular of the right ventricle and the main pulmonary artery. The left pump was applied between the apex of the left ventricle and the thoracic descending aorta. As for anticoagulation, heparin was administered at the first postoperative week and then converted to warfarin sodium from the second week after surgery. Both pump flow rates were controlled maintaining a pulmonary arterial flow of less than 160 ml/kg/min for the sake of avoidance of pulmonary congestion. Blood sampling was done to assess visceral organ function, and the data regarding pump performance were collected. After encountering the endpoint, which the study could not keep for any reasons, necropsy and histopathological examinations were performed. The first 2 cases were terminated within 1 week. Deterioration of the pump flow due to suction phenomenon was recognized in both cases. To avoid the suction phenomenon, a flexible conduit attached on the inlet conduit was designed and implanted. After using the flexible inflow conduit, the required power and the rotational speed were reduced. Furthermore, the suction

  14. Evaluation of hydraulic radial forces on the impeller by the volute in a centrifugal rotary blood pump.

    PubMed

    Boehning, Fiete; Timms, Daniel L; Amaral, Felipe; Oliveira, Leonardo; Graefe, Roland; Hsu, Po-Lin; Schmitz-Rode, Thomas; Steinseifer, Ulrich

    2011-08-01

    In many state-of-the-art rotary blood pumps for long-term ventricular assistance, the impeller is suspended within the casing by magnetic or hydrodynamic means. For the design of such suspension systems, profound knowledge of the acting forces on the impeller is crucial. Hydrodynamic bearings running at low clearance gaps can yield increased blood damage and magnetic bearings counteracting high forces consume excessive power. Most current rotary blood pump devices with contactless bearings are centrifugal pumps that incorporate a radial diffuser volute where hydraulic forces on the impeller develop. The yielding radial forces are highly dependent on impeller design, operating point and volute design. There are three basic types of volute design--singular, circular, and double volute. In this study, the hydraulic radial forces on the impeller created by the volute in an investigational centrifugal blood pump are evaluated and discussed with regard to the choice of contactless suspension systems. Each volute type was tested experimentally in a centrifugal pump test setup at various rotational speeds and flow rates. For the pump's design point at 5 L/min and 2500 rpm, the single volute had the lowest radial force (∼0 N), the circular volute yielded the highest force (∼2 N), and the double volute possessed a force of approx. 0.5 N. Results of radial force magnitude and direction were obtained and compared with a previously performed computational fluid dynamics (CFD) study.

  15. A novel design of spiral groove bearing in a hydrodynamically levitated centrifugal rotary blood pump.

    PubMed

    Han, Qing; Zou, Jun; Ruan, Xiaodong; Fu, Xin; Yang, Huayong

    2012-08-01

    Good washout is very important in spiral groove bearing (SGB) designs when applied to blood pumps due to the micrometer scales of lubrication films and groove depths. To improve washout, flow rate or leakage through SGBs should be as large as possible. However, this special goal violates conventional SGB designs in which no leakage is desired as the leakage would decrease load-carrying capacity significantly. So, a design concept is formed fulfilling the two goals of high load-carrying capacity and large flow rate: let groove width decrease along flow path and the mating surface of the rotor rotate with a direction facilitating the flow through the grooves. Under this concept, a novel SGB is designed, contrary to conventional ones, with groove width decreasing with increasing spiral radius. This SGB is mounted on the motionless upper plate of our designed centrifugal blood pump, with the mating surface of rotor rotating with a direction facilitating the outward flow. To assess SGB designs, a characteristic plane is originally presented relating to pressure-normalized load-carrying capacity and flow rate. Comparisons between various kinds of SGB designs are made, and computational fluid dynamics (CFD) results are plotted in this characteristic plane from which load/flow performances can be directly read out. CFD and comparison results show that the new designs have superior load/flow characteristics. However, the impact of SGB designs upon hemolysis/thrombus formation is still to be verified according to the concept presented.

  16. In vitro study to estimate particle release from a centrifugal blood pump.

    PubMed

    Takami, Yoshiyuki

    2006-05-01

    Centrifugal pumps have been increasingly used in clinical settings. Like roller pumps, centrifugal pumps can cause debris release due to mechanical stress. The objectives of this study were to evaluate in vitro the particle release from a centrifugal pump, Gyro Pump (Japan Medical Materials Co., Osaka, Japan), which is a pivot-bearing supported pump clinically used in Japan, and to identify the released particles. In the clean room Class 10,000, the pump was operated for 24 h at 4000 rpm and 6 L/min in a mock loop filled with lactated Ringer's solution. After 24 h, the sample fluid and a blank were filtered with a 0.45-microm membrane filter for microscopic counting, followed by observation with a scanning electron microscope and element analysis with an X-ray spectrometer. Microscopic countings were 128 +/- 42 in the test samples (n = 10) of the Gyro Pump and 98 +/- 42 in the blank samples (n = 10) (P = 0.12). The oxygen/carbon atomic ratio of the particles in the test samples was 0.32 +/- 0.06, which was similar to the ratio of the particles in the blank sample (0.34 +/- 0.06). The profiles of elements with an X-ray spectrometer showed that the released particles from the Gyro Pump were not derived from the pump materials. In conclusion, an in vitro test system has been established for estimation of particle release from a centrifugal pump. Based upon the results with the system, the Gyro Pump with a pivot-bearing system has little risk to release debris particles even in a severe condition.

  17. Bearing gap adjustment for improvement of levitation performance in a hydrodynamically levitated centrifugal blood pump.

    PubMed

    Kosaka, Ryo; Yoshida, Fumihiko; Nishida, Masahiro; Maruyama, Osamu; Kawaguchi, Yasuo; Yamane, Takashi

    2015-01-01

    The purpose of the present study is to investigate a bearing gap adjustment for improvement of levitation performance in a hydrodynamically levitated centrifugal blood pump to realize a blood pump with a low hemolysis level. The impeller levitates axially by balancing a gravitational force, buoyancy, a magnetic force, and hydrodynamic forces on the top and bottom sides of the impeller. To adjust the levitation position of the impeller, the balance of acting forces on the impeller was adjusted by changing the shroud area on the bottom impeller. Three pumps having various shroud area were prepared as tested models: 817 mm(2) (HH-S), 875 mm(2) (HH-M) and 931 mm(2) (HH-L). First, for evaluating the bearing gap adjustment, the bearing gap was estimated by calculating a balancing position of the acting forces on the impeller. We actually measured the gravitational force, buoyancy and the magnetic force, and numerically analyzed hydrodynamic forces on the top and bottom sides of the impeller. Second, to verify accuracy of the estimated bearing gap, the measurement test of the bearing gap was performed. Finally, an in-vitro hemolysis test was performed to evaluate a hemolysis level of the pump. As a result, bottom bearing gaps were estimated as 40 μm (HH-S), 60 μm (HH-M) and 238 μm (HH-L). In the measurement test, bottom bearing gaps were measured as 63 μm (HH-S), 219 μm (HH-M), and 231 μm (HH-L). The estimated bearing gaps had positively correlated with the measured bearing gaps in relation to the shroud area on the impeller. In the hemolysis test, hemolysis level in every model was almost equivalent to that of BPX-80, when the bearing gap was adjusted greater than 60 μm. We could adjust the bearing gap by changing the shroud area on the impeller for improvement of levitation performance to realize a blood pump with a low hemolysis level.

  18. Blood damage related to cardiopulmonary bypass: in vivo and in vitro comparison of two different centrifugal pumps.

    PubMed

    Paparella, Domenico; Galeone, Antonella; Venneri, Maria Teresa; Coviello, Maria; Visicchio, Giuseppe; Cappabianca, Giangiuseppe; Maselli, Giorgia; Marraudino, Nicola; Quaranta, Michele; De Luca Tupputi Schinosa, Luigi

    2004-01-01

    Cardiopulmonary bypass (CPB) induces hemolysis and the activation of the inflammatory and coagulation systems. Several components of the CPB equipment may contribute to such phenomenon. We tested the effects of two differently designed centrifugal pumps (Bio-Pump, Medtronic and Revolution, Cobe) on several markers of hemolysis, coagulation, and inflammation: plasma free hemoglobin,prothrombin fragment 1.2, platelet factor 4, and P-selectin. Twenty patients requiring coronary artery bypass grafting were randomized to undergo CPB with one of the study centrifugal pumps, and 10 experiments (5 for each pump) were performed with a closed loop circuit to assess pumps' performances over 6 circulation hours using human blood. CPB induced a significant elevation of all the tested markers. Neither in the in vivo nor in the in vitro study were significant differences observed between the groups. Because the Revolution centrifugal pump, which was recently designed and distributed, produced results comparable with those obtained with the BioPump, it should be considered as safe as the Bio-Pump to perform clinical CPB.

  19. Shaft/shaft-seal interface characteristics of a multiple disk centrifugal blood pump.

    PubMed

    Manning, K B; Miller, G E

    1999-06-01

    A multiple disk centrifugal pump (MDCP) is under investigation as a potential left ventricular assist device. As is the case with most shaft driven pumps, leakage problems around the shaft/shaft seal interface are of major interest. If leakage were to occur during or after implantation, potential events such as blood loss, clotting, blood damage, and/or infections might result in adverse effects for the patient. Because these effects could be quite disastrous, potential shaft and shaft seal materials have been investigated to determine the most appropriate course to limit these effects. Teflon and nylon shaft seals were analyzed as potential candidates along with a stainless steel shaft and a Melonite coated shaft. The materials and shafts were evaluated under various time durations (15, 30, 45, and 60 min), motor speeds (800, 1,000, 1,200, and 1,400 rpm), and outer diameters (1/2 and 3/4 inches). The motor speed and geometrical configurations were typical for the MDCP under normal physiologic conditions. An air and water study was conducted to analyze the inner diameter wear, the inner temperature values, and the outer temperature values. Statistical comparisons were computed for the shaft seal materials, the shafts, and the outer diameters along with the inner and outer temperatures. The conclusions made from the results indicate that both the tested shaft seal materials and shaft materials are not ideal candidates to be used for the MDCP. Teflon experienced a significant amount of wear in air and water studies. Nylon did experience little wear, but heat generation was an evident problem. A water study on nylon was not conducted because of its molecular structure.

  20. [Research on magnetic coupling centrifugal blood pump control based on a self-tuning fuzzy PI algorithm].

    PubMed

    Yang, Lei; Yang, Ming; Xu, Zihao; Zhuang, Xiaoqi; Wang, Wei; Zhang, Haibo; Han, Lu; Xu, Liang

    2014-10-01

    The purpose of this paper is to report the research and design of control system of magnetic coupling centrifugal blood pump in our laboratory, and to briefly describe the structure of the magnetic coupling centrifugal blood pump and principles of the body circulation model. The performance of blood pump is not only related to materials and structure, but also depends on the control algorithm. We studied the algorithm about motor current double-loop control for brushless DC motor. In order to make the algorithm adjust parameter change in different situations, we used the self-tuning fuzzy PI control algorithm and gave the details about how to design fuzzy rules. We mainly used Matlab Simulink to simulate the motor control system to test the performance of algorithm, and briefly introduced how to implement these algorithms in hardware system. Finally, by building the platform and conducting experiments, we proved that self-tuning fuzzy PI control algorithm could greatly improve both dynamic and static performance of blood pump and make the motor speed and the blood pump flow stable and adjustable.

  1. Estimation of left ventricular recovery level based on the motor current waveform analysis on circulatory support with centrifugal blood pump.

    PubMed

    Takahashi, K; Uemura, M; Watanabe, N; Ohuchi, K; Nakamura, M; Fukui, Y; Sakamoto, T; Takatani, S

    2001-09-01

    In a mock circulatory loop simulating the left heart bypass using a centrifugal blood pump, analysis of the motor current waveform of the centrifugal pump was performed to derive a useful parameter to evaluate the status of ventricular function. The relationship between the peak, amplitude, and the peak of the fundamental frequency of the power spectral density of the periodic motor current waveform (MCpsdP) that reflected the pulsatile ventricular pressure, and the peak of the left ventricular pressure (LVP) was examined. Although both peak and amplitude of the motor current waveform showed an excellent correlation with the peak LVP, they failed to predict the opening of the aortic valve. The MCpsdP that corresponds to the frequency of the heart rate showed an excellent correlation with the peak LVP throughout the LVP levels, but the slope between them changed with the opening of the aortic valve. Thus, it is possible to follow the change in the LVP and detect even the opening of the aortic valve, and, hence, the recovery of the left ventricle. However, the slope of the linear regression equation varied, depending on the pump speed. This result implies that the MCpsdP can be possibly used to follow the change of ventricular function during circulatory assistance with a centrifugal blood pump as well as to control the pump speed in response to varying ventricular function.

  2. Feasibility of an air motor-driven centrifugal blood-pumping system.

    PubMed

    Forbes, S J; Akula, J; Smith, W A

    1996-07-01

    The use of cardiopulmonary bypass (CPB) is extending out of the cardiac surgery operating room into new venues. The long-term goal of this project is the development of a completely disposable temporary-use CPB system that could be economically distributed to all of the units where it might be needed. Centrifugal blood pumps have demonstrated successful and widespread use. However, they are not as widely available as might be desired because they require a large and expensive console. An inexpensive, small, lightweight, disposable unit, in contrast, could be widely distributed for emergency care of patients and would be logistically practical for patient transportation between the presenting institution and a major cardiac care facility equipped for definitive treatment. An air motor might be an approach to such a device. The current research project underway at the University of Akron in conjunction with the Cleveland Clinic Foundation has focused on the following key feasibility issues: air consumption, air motor noise, and sealing the rotating shaft. Prototypes have been constructed from commercially available vane and turbine motors. Early studies have demonstrated favorable results with regard to air consumption and shaft sealing and directions for handling air motor noise.

  3. Design analysis and performance assessment of hybrid magnetic bearings for a rotary centrifugal blood pump.

    PubMed

    Ren, Zhaohui; Jahanmir, Said; Heshmat, Hooshang; Hunsberger, Andrew Z; Walton, James F

    2009-01-01

    A hybrid magnetic bearing system was designed for a rotary centrifugal blood pump being developed to provide long-term circulatory support for heart failure patients. This design consists of two compact bearings to suspend the rotor in five degrees-of-freedom with single axis active control. Permanent magnets are used to provide passive radial support and electromagnets to maintain axial stability of the rotor. Characteristics of the passive radial and active thrust magnetic bearing system were evaluated by the electromagnetic finite element analysis. A proportional-integral-derivative controller with force balance algorithm was implemented for closed loop control of the magnetic thrust bearing. The control position is continuously adjusted based on the electrical energy in the bearing coils, and thus passive magnetic forces carry static thrust loads to minimize the bearing current. Performance of the magnetic bearing system with associated control algorithm was evaluated at different operating conditions. The bearing current was significantly reduced with the force balance control method and the power consumption was below 0.5 W under various thrust loads. The bearing parameters predicted by the analysis were validated by the experimental data.

  4. Feasibility of a miniature centrifugal rotary blood pump for low-flow circulation in children and infants.

    PubMed

    Takatani, Setsuo; Hoshi, Hideo; Tajima, Kennichi; Ohuchi, Katsuhiro; Nakamura, Makoto; Asama, Junichio; Shimshi, Tadahiko; Yoshikawa, Masaharu

    2005-01-01

    In this study, a seal-less, tiny centrifugal rotary blood pump was designed for low-flow circulatory support in children and infants. The design was targeted to yield a compact and priming volume of 5 ml with a flow rate of 0.5-4 l/min against a head pressure of 40-100 mm Hg. To meet the design requirements, the first prototype had an impeller diameter of 30 mm with six straight vanes. The impeller was supported with a needle-type hydrodynamic bearing and was driven with a six-pole radial magnetic driver. The external pump dimensions included a pump head height of 20 mm, diameter of 49 mm, and priming volume of 5 ml. The weight was 150 g, including the motor driver. In the mock circulatory loop, using fresh porcine blood, the pump yielded a flow of 0.5-4.0 l/min against a head pressure of 40-100 mm Hg at a rotational speed of 1800-4000 rpm using 1/4" inflow and outflow conduits. The maximum flow and head pressure of 5.25 l/min and 244 mm Hg, respectively, were obtained at a rotational speed of 4400 rpm. The maximum electrical-to-hydraulic efficiency occurred at a flow rate of 1.5-3.5 l/min and at a rotational speed of 2000-4400 rpm. The normalized index of hemolysis, which was evaluated using fresh porcine blood, was 0.0076 g/100 l with the impeller in the down-mode and a bearing clearance of 0.1 mm. Further refinement in the bearing and magnetic coupler are required to improve the hemolytic performance of the pump. The durability of the needle-type hydrodynamic bearing and antithrombotic performance of the pump will be performed before clinical applications. The tiny centrifugal blood pump meets the flow requirements necessary to support the circulation of pediatric patients.

  5. A cost-effective extracorporeal magnetically-levitated centrifugal blood pump employing a disposable magnet-free impeller.

    PubMed

    Hijikata, W; Mamiya, T; Shinshi, T; Takatani, S

    2011-12-01

    In the field of rotary blood pumps, contactless support of the impeller by a magnetic bearing has been identified as a promising method to reduce blood damage and enhance durability. The authors developed a two-degrees-of-freedom radial controlled magnetic bearing system without a permanent magnet in the impeller in order that a low-cost disposable pump-head for an extracorporeal centrifugal blood pump could be manufactured more easily. Stable levitation and contactless rotation of the 'magnet-free' impeller were realized for a prototype blood-pump that made use of this magnetic bearing. The run-out of the impeller position at between 1000 r/min and 3000 r/min was less than 40 microm in the radial-controlled directions. The total power consumption of the magnetic bearing was less than 1 W at the same rotational speeds. When the pump was operated, a flow rate of 5 l/min against a head pressure of 78.66 kPa was achieved at a rotational speed of 4000 r/min, which is sufficient for extracorporeal circulation support. The proposed technology offers the advantage of low-cost mass production of disposable pump heads.

  6. Optical Dynamic Analysis of Thrombus Inside a Centrifugal Blood Pump During Extracorporeal Mechanical Circulatory Support in a Porcine Model.

    PubMed

    Fujiwara, Tatsuki; Sakota, Daisuke; Ohuchi, Katsuhiro; Endo, Shu; Tahara, Tomoki; Murashige, Tomotaka; Kosaka, Ryo; Oi, Keiji; Mizuno, Tomohiro; Maruyama, Osamu; Arai, Hirokuni

    2017-03-20

    Complications due to pump thrombus remain the weak point of mechanical circulatory support (MCS), such as the use of a left ventricular assist device (LVAD) or extracorporeal membrane oxygenation, leading to poor outcomes. Hyperspectral imaging (HSI) is an effective imaging method using a hyperspectral (HS) camera, which comprises a spectrophotometer and a charge-coupled device camera to discriminate thrombus from whole blood. Animal experiments were conducted to analyze dynamic imaging of thrombus inside a prototype of a hydrodynamically levitated centrifugal blood pump using an HSI system. Six pigs were divided into a venous circulation group (n = 3) and an arterial circulation group (n = 3). Inflow and outflow cannulae were inserted into the jugular veins in the venous circulation group. The latter simulated an LVAD application. To create thrombogenic conditions, pump flow was maintained at 1 L/min without anticoagulation. An image of the bottom surface of the pump was captured by the HS camera every 4 nm over the wavelength range of 608-752 nm. Real-time dynamic images of the inside of the pump were displayed on the monitor. Appearance of an area displaying thrombus was detected within 24 h after the start of the circulation in every experiment. This imaging system also succeeded in determining the origins of pump thrombus: from inside the pump in two cases, and from outside in four cases. Two main possible sources of pump thrombus originating outside the pump were identified on autopsy: wedge thrombus around the inflow cannula; and string-like thrombus at the junction between the pump inlet and circuit tube. The results of this study from close observation of the changing appearance of pump thrombus may contribute to improvements in the safety of extracorporeal MCS.

  7. Measurement of the rotor motion and corresponding hemolysis of a centrifugal blood pump with a magnetic and hydrodynamic hybrid bearing.

    PubMed

    Kataoka, Hiroyuki; Kimura, Yuichi; Fujita, Hajime; Takatani, Setsuo

    2005-07-01

    This study proposed a centrifugal blood pump with a novel magnetic and hydrodynamic hybrid passive bearing, which consisted of a plain journal bearing for radial stability and a permanent magnetic bearing for axial and tilting stability. We measured the radial motion of the bearing and performed hemolysis tests for the different radial clearance sizes. In the results, it appeared that the radial motion had two modes: the stable center mode, in which the radius of the radial motion rapidly converged to less than 20 microm; and the unstable circle mode, in which the rotor suspension linearly increased with the rotation speed. It also appeared that the pumps with the radial clearance of 80 microm caused more hemolysis than with the smaller clearance sizes in the circle mode. The circle mode was avoidable by the higher rotation or the asymmetric pump structure, but the mechanism of hemolysis in this mode was still unclear.

  8. Efficiency of an air filter at the drainage site in a closed circuit with a centrifugal blood pump: an in vitro study.

    PubMed

    Mitsumaru, A; Yozu, R; Matayoshi, T; Morita, M; Shin, H; Tsutsumi, K; Iino, Y; Kawada, S

    2001-01-01

    In a closed circuit with a centrifugal blood pump, one of the serious obstacles to clinical application is sucking of air bubbles into the drainage circuit. The goal of this study was to investigate the efficiency of an air filter at the drainage site. We used whole bovine blood and the experimental circuit consisted of a drainage circuit, two air filters, a centrifugal blood pump, a membrane oxygenator, a return circuit, and a reservoir. Air was injected into the drainage circuit with a roller pump, and the number and size of air bubbles were measured. The air filter at the drainage site could remove the air bubbles (>40 microm) by itself, but adding a vacuum removed more bubbles (>40 microm) than without vacuum. Our results suggest that an air filter at the drainage site could effectively remove air bubbles, and that adding the filter in a closed circuit with a centrifugal blood pump would be safer.

  9. Geometric optimization of a step bearing for a hydrodynamically levitated centrifugal blood pump for the reduction of hemolysis.

    PubMed

    Kosaka, Ryo; Yada, Toru; Nishida, Masahiro; Maruyama, Osamu; Yamane, Takashi

    2013-09-01

    A hydrodynamically levitated centrifugal blood pump with a semi-open impeller has been developed for mechanical circulatory assistance. However, a narrow bearing gap has the potential to cause hemolysis. The purpose of the present study is to optimize the geometric configuration of the hydrodynamic step bearing in order to reduce hemolysis by expansion of the bearing gap. First, a numerical analysis of the step bearing, based on lubrication theory, was performed to determine the optimal design. Second, in order to assess the accuracy of the numerical analysis, the hydrodynamic forces calculated in the numerical analysis were compared with those obtained in an actual measurement test using impellers having step lengths of 0%, 33%, and 67% of the vane length. Finally, a bearing gap measurement test and a hemolysis test were performed. As a result, the numerical analysis revealed that the hydrodynamic force was the largest when the step length was approximately 70%. The hydrodynamic force calculated in the numerical analysis was approximately equivalent to that obtained in the measurement test. In the measurement test and the hemolysis test, the blood pump having a step length of 67% achieved the maximum bearing gap and reduced hemolysis, as compared with the pumps having step lengths of 0% and 33%. It was confirmed that the numerical analysis of the step bearing was effective, and the developed blood pump having a step length of approximately 70% was found to be a suitable configuration for the reduction of hemolysis.

  10. Influence of radial clearance and rotor motion to hemolysis in a journal bearing of a centrifugal blood pump.

    PubMed

    Kataoka, Hiroyuki; Kimura, Yuichi; Fujita, Hajime; Takatani, Setsuo

    2006-11-01

    Hemolysis due to narrow clearance of noncontact bearings is a critical problem for rotary blood pumps. We developed a centrifugal blood pump with a magnetic and hydrodynamic hybrid bearing, and found that the hemolysis in the narrow clearance depends not only on the clearance size, but also on the rotor stability. In this study, we quantified the relation between the hemolysis, radial clearance (c), and rotor stability through the measurement of the rotor motion and hemolysis. As a result, it was confirmed that the rotor of the current pump is stabilized within the oscillation of 20 microm in blood, and the hemolysis decreases with increase in the c, which is the opposite in the unstable rotor motion with the previous pump. In order to theoretically discuss this hemolysis tendency, we implemented hemolysis estimation in the c according to hydrodynamics and hemodynamics. This estimation can represent the measured hemolysis tendency, and revealed that the flow rate has large influence on the hemolysis in the c.

  11. Centrifugal pumps for rocket engines

    NASA Technical Reports Server (NTRS)

    Campbell, W. E.; Farquhar, J.

    1974-01-01

    The use of centrifugal pumps for rocket engines is described in terms of general requirements of operational and planned systems. Hydrodynamic and mechanical design considerations and techniques and test procedures are summarized. Some of the pump development experiences, in terms of both problems and solutions, are highlighted.

  12. Estimation of the radial force using a disturbance force observer for a magnetically levitated centrifugal blood pump.

    PubMed

    Pai, C N; Shinshi, T; Shimokohbe, A

    2010-01-01

    Evaluation of the hydraulic forces in a magnetically levitated (maglev) centrifugal blood pump is important from the point of view of the magnetic bearing design. Direct measurement is difficult due to the absence of a rotor shaft, and computational fluid dynamic analysis demands considerable computational resource and time. To solve this problem, disturbance force observers were developed, using the radial controlled magnetic bearing of a centrifugal blood pump, to estimate the radial forces on the maglev impeller. In order to design the disturbance observer, the radial dynamic characteristics of a maglev impeller were evaluated under different working conditions. It was observed that the working fluid affects the additional mass and damping, while the rotational speed affects the damping and stiffness of the maglev system. Based on these results, disturbance force observers were designed and implemented. The designed disturbance force observers present a bandwidth of 45 Hz. In non-pulsatile conditions, the magnitude of the estimated radial thrust increases in proportion to the flowrate, and the rotational speed has little effect on the force direction. At 5 l/min against 100 mmHg, the estimated radial thrust is 0.95 N. In pulsatile conditions, this method was capable of estimating the pulsatile radial thrust with good response.

  13. The spiral groove bearing as a mechanism for enhancing the secondary flow in a centrifugal rotary blood pump.

    PubMed

    Amaral, Felipe; Gross-Hardt, Sascha; Timms, Daniel; Egger, Christina; Steinseifer, Ulrich; Schmitz-Rode, Thomas

    2013-10-01

    The rapid evolution of rotary blood pump (RBP) technology in the last few decades was shaped by devices with increased durability, frequently employing magnetic or hydrodynamic suspension techniques. However, the potential for low flow in small gaps between the rotor and pump casing is still a problem for hemocompatibility. In this study, a spiral groove hydrodynamic bearing (SGB) is applied with two distinct objectives: first, as a mechanism to enhance the washout in the secondary flow path of a centrifugal RBP, lowering the exposure to high shear stresses and avoiding thrombus formation; and second, as a way to allow smaller gaps without compromising the washout, enhancing the overall pump efficiency. Computational fluid dynamics was applied and verified via bench-top experiments. An optimization of selected geometric parameters (groove angle, width and depth) focusing on the washout in the gap rather than generating suspension force was conducted. An optimized SGB geometry reduced the residence time of the cells in the gap from 31 to 27 ms, an improvement of 14% compared with the baseline geometry of 200 μm without grooves. When optimizing for pump performance, a 15% smaller gap yielded a slightly better rate of fluid exchange compared with the baseline, followed by a 22% reduction in the volumetric loss from the primary pathway. Finally, an improved washout can be achieved in a pulsatile environment due to the SGB ability to pump inwardly, even in the absence of a pressure head.

  14. Flow-Field Simulations and Hemolysis Estimates for the Food and Drug Administration Critical Path Initiative Centrifugal Blood Pump.

    PubMed

    Heck, Margaret L; Yen, Allen; Snyder, Trevor A; O'Rear, Edgar A; Papavassiliou, Dimitrios V

    2017-02-07

    The design of blood pumps for use in ventricular assist devices, which provide life-saving circulatory support in patients with heart failure, require remarkable precision and attention to detail to replicate the functionality of the native heart. The United States Food and Drug Administration (FDA) initiated a Critical Path Initiative to standardize and facilitate the use of computational fluid dynamics in the study and development of these devices. As a part of the study, a simplified centrifugal blood pump model generated by computer-aided design was released to universities and laboratories nationwide. The effects of changes in fluid rheology due to temperature, hematocrit, and turbulent flow on key metrics of the FDA pump were examined in depth using results from a finite volume-based commercial computational fluid dynamics code. Differences in blood damage indices obtained using Eulerian and Lagrangian formulations were considered. These results are presented and discussed awaiting future validation using experimental results, which will be released by the FDA at a future date.

  15. Computational fluid dynamics prediction of blood damage in a centrifugal pump.

    PubMed

    Song, Xinwei; Throckmorton, Amy L; Wood, Houston G; Antaki, James F; Olsen, Don B

    2003-10-01

    This study explores a quantitative evaluation of blood damage that occurs in a continuous flow left ventricular assist device due to fluid stress. Computational fluid dynamics (CFD) analysis is used to track the shear stress history of 388 particle streaklines. The accumulation of shear and exposure time is integrated along the streaklines to evaluate the levels of blood trauma. This analysis, which includes viscous and turbulent stresses, provides a statistical estimate of possible damage to cells flowing through the pump. In vitro normalized index of hemolysis values for clinically available ventricular assist devices were compared to our damage indices. This allowed for an order of magnitude comparison between our estimations and experimentally measured hemolysis levels, which resulted in a reasonable correlation. This work ultimately demonstrates that CFD is a convenient and effective approach to analyze the Lagranian behavior of blood in a heart assist device.

  16. Intrathoracic and intraabdominal wall implantation of a centrifugal blood pump for circulatory assist.

    PubMed

    Wakisaka, Y; Taenaka, Y; Chikanari, K; Okuzono, Y; Nishimura, T; Endo, S; Nakatani, T; Takano, H

    1998-06-01

    An implantable centrifugal pump (ICP) 320 ml in volume and 830 g in weight has been developed for prolonged circulatory assist. The antithrombogenicity of the ICP is provided by a balancing hole in the center of the impeller. The watertightness and histocompatibility of the ICP are supported by its silicone ring seal and its casing of titanium and acrylic resin, respectively. The total efficiency of the ICP was 30% at a 5 L/min flow rate and a 100 mm Hg head. The heat generation, watertightness, and anatomical fitting of the ICP were assessed in an intrathoracic implantation in a goat (66 kg) and in an intraabdominal wall implantation in a goat (70 kg). Warfarin was given for anticoagulation in each experiment to keep the prothrombin time around 1.7 times that of the control. The temperatures of the pump surface, the pleura, and the room were measured every 3 h. Anatomical fitting was evaluated by pathological observation after the termination of the experiment. The ICP could run for 40 days in the chest cavity and for 11 days in the abdominal wall. The temperature of the motor remained about 1.8 degrees C higher than the reference in both experiments. The ICP was completely covered by a layer of smooth fibrous tissue. The moisture content of the seals remained normal. Although a small amount of atelectasis was found in the lingula, neither lung adhesion nor necrotic change of the chest wall was observed. The inflammation of the surrounding tissue including foreign body reaction and thermal burn was minimal. In conclusion, the ICP has satisfied in vivo testing of its watertightness, exothermicity, and anatomical fitting.

  17. Improvement of hemocompatibility in centrifugal blood pump with hydrodynamic bearings and semi-open impeller: in vitro evaluation.

    PubMed

    Kosaka, Ryo; Maruyama, Osamu; Nishida, Masahiro; Yada, Toru; Saito, Sakae; Hirai, Shusaku; Yamane, Takashi

    2009-10-01

    We have developed a noncontact-type centrifugal blood pump with hydrodynamic bearings and a semi-open impeller for mechanical circulatory assist. The impeller is levitated by an original spiral-groove thrust bearing and a herringbone-groove journal bearing, without any additional displacement-sensing module or additional complex control circuits. The pump was improved by optimizing the groove direction of the spiral-groove thrust bearing and the pull-up magnetic force between the rotor magnet and the stator coil against the impeller. To evaluate hemocompatibility, we conducted a levitation performance test and in vitro hemocompatibility tests by means of a mock-up circulation loop. In the hemolysis test, the normalized index of hemolysis was reduced from 0.721 to 0.0335 g/100 L corresponding to an expansion of the bearing gap from 1.1 to 56.1 microm. In the in vitro antithrombogenic test, blood pumps with a wide thrust bearing gap were effective in preventing thrombus formation. Through in vitro evaluation tests, we confirmed that hemocompatibility was improved by balancing the hydrodynamic fluid dynamics and magnetic forces.

  18. Disposable MagLev centrifugal blood pump utilizing a cone-shaped impeller.

    PubMed

    Hijikata, Wataru; Sobajima, Hideo; Shinshi, Tadahiko; Nagamine, Yasuyuki; Wada, Suguru; Takatani, Setsuo; Shimokohbe, Akira

    2010-08-01

    To enhance the durability and reduce the blood trauma of a conventional blood pump with a cone-shaped impeller, a magnetically levitated (MagLev) technology has been applied to the BioPump BPX-80 (Medtronic Biomedicus, Inc., Minneapolis, MN, USA), whose impeller is supported by a mechanical bearing. The MagLev BioPump (MagLev BP), which we have developed, has a cone-shaped impeller, the same as that used in the BPX-80. The suspension and driving system, which is comprised of two degrees of freedom, radial-controlled magnetic bearing, and a simply structured magnetic coupling, eliminates any physical contact between the impeller and the housing. To reduce both oscillation of the impeller and current in the coils, the magnetic bearing system utilizes repetitive and zero-power compensators. In this article, we present the design of the MagLev mechanism, measure the levitational accuracy of the impeller and pressure-flow curves (head-quantity [HQ] characteristics), and describe in vitro experiments designed to measure hemolysis. For the flow-induced hemolysis of the initial design to be reduced, the blood damage index was estimated by using computational fluid dynamics (CFD) analysis. Stable rotation of the impeller in a prototype MagLev BP from 0 to 2750 rpm was obtained, yielding a flow rate of 5 L/min against a head pressure in excess of 250 mm Hg. Because the impeller of the prototype MagLev BP is levitated without contact, the normalized index of hemolysis was 10% less than the equivalent value with the BPX-80. The results of the CFD analysis showed that the shape of the outlet and the width of the fluid clearances have a large effect on blood damage. The prototype MagLev BP satisfied the required HQ characteristics (5 L/min, 250 mm Hg) for extracorporeal circulation support with stable levitation of the impeller and showed an acceptable level of hemolysis. The simulation results of the CFD analysis indicated the possibility of further reducing the blood damage of

  19. High efficiency centrifugal pump

    SciTech Connect

    Nasvytis, P.J.; Jahrstorfer, G.W.

    1983-10-11

    A high speed fuel pump for a gas turnbine engine has a positively-driven shroud positioned between a main impeller and the wall of a pumping cavity to reduce impeller drag. The shroud is formed by a first disc having a boost impeller connected to its central hub portion and a second disc having a gear carried by its central hub portion. The main drive shaft assembly to which the main impeller is connected, carries a gear which meshes with gear mounted upon a shaft. The shaft also carries a gear which meshes with the gear. The gears are sized so that the shroud is driven at one-half the speed of the main impeller in order to maximize impeller drag reduction and enhance pumping capability when severe inlet conditions are present at the pump inlet.

  20. Evaluation of a Spiral Groove Geometry for Improvement of Hemolysis Level in a Hydrodynamically Levitated Centrifugal Blood Pump.

    PubMed

    Murashige, Tomotaka; Kosaka, Ryo; Sakota, Daisuke; Nishida, Masahiro; Kawaguchi, Yasuo; Yamane, Takashi; Maruyama, Osamu

    2015-08-01

    The purpose of this study is to evaluate a spiral groove geometry for a thrust bearing to improve the hemolysis level in a hydrodynamically levitated centrifugal blood pump. We compared three geometric models: (i) the groove width is the same as the ridge width at any given polar coordinate (conventional model); (ii) the groove width contracts inward from 9.7 to 0.5 mm (contraction model); and (iii) the groove width expands inward from 0.5 to 4.2 mm (expansion model). To evaluate the hemolysis level, an impeller levitation performance test and in vitro hemolysis test were conducted using a mock circulation loop. In these tests, the driving conditions were set at a pressure head of 200 mm Hg and a flow rate of 4.0 L/min. As a result of the impeller levitation performance test, the bottom bearing gaps of the contraction and conventional models were 88 and 25 μm, respectively. The impeller of the expansion model touched the bottom housing. In the hemolysis test, the relative normalized index of hemolysis (NIH) ratios of the contraction model in comparison with BPX-80 and HPM-15 were 0.6 and 0.9, respectively. In contrast, the relative NIH ratios of the conventional model in comparison with BPX-80 and HPM-15 were 9.6 and 13.7, respectively. We confirmed that the contraction model achieved a large bearing gap and improved the hemolysis level in a hydrodynamically levitated centrifugal blood pump.

  1. Five-week use of a monopivot centrifugal blood pump as a right ventricular assist device in severe dilated cardiomyopathy.

    PubMed

    Inoue, Takamichi; Kitamura, Tadashi; Torii, Shinzo; Hanayama, Naoji; Oka, Norihiko; Itatani, Keiichi; Tomoyasu, Takahiro; Irisawa, Yusuke; Shibata, Miyuki; Hayashi, Hidenori; Ono, Minoru; Miyaji, Kagami

    2014-03-01

    Right heart failure is a critical complication in patients requiring mechanical ventricular support. However, it is often difficult to provide adequate right ventricular support in the acute phase. A 41-year-old woman diagnosed with dilated cardiomyopathy with severe right heart failure underwent implantation of a paracorporeal pulsatile left ventricular assist device (LVAD, Nipro Corporation, Tokyo, Japan) and a MERA monopivot centrifugal pump (Senko Medical Instrument Manufacturing Co., Ltd., Tokyo, Japan) as a right ventricular assist device (RVAD). The patient developed ischemic enteritis 3 weeks after surgery, necessitating fasting and reversal of anticoagulation therapy. A target international normalized ratio of 1.5 was selected, and aspirin administration was discontinued. Following recovery without thromboembolic events, the patient failed the RVAD discontinuation test. Five weeks after surgery, the monopivot centrifugal pump was exchanged for a pulsatile pump. No thrombus was evident on the centrifugal pump. The patient was undergoing cardiac rehabilitation at the time of this writing and awaiting heart transplantation.

  2. Optimal bearing gap of a multiarc radial bearing in a hydrodynamically levitated centrifugal blood pump for the reduction of hemolysis.

    PubMed

    Kosaka, Ryo; Yasui, Kazuya; Nishida, Masahiro; Kawaguchi, Yasuo; Maruyama, Osamu; Yamane, Takashi

    2014-09-01

    We have developed a hydrodynamically levitated centrifugal pump as a bridge-to-decision device. The purpose of the present study is to determine the optimal bearing gap of a multiarc radial bearing in the developed blood pump for the reduction of hemolysis. We prepared eight pump models having bearing gaps of 20, 30, 40, 80, 90, 100, 180, and 250 μm. The driving conditions were set to a pressure head of 200 mm Hg and a flow rate of 4 L/min. First, the orbital radius of the impeller was measured for the evaluation of the impeller stability. Second, the hemolytic property was evaluated in an in vitro hemolysis test. As a result, the orbital radius was not greater than 15 μm when the bearing gap was between 20 and 100 μm. The relative normalized index of hemolysis (NIH) ratios in comparison with BPX-80 were 37.67 (gap: 20 μm), 0.95 (gap: 30 μm), 0.96 (gap: 40 μm), 0.82 (gap: 80 μm), 0.77 (gap: 90 μm), 0.92 (gap: 100 μm), 2.76 (gap: 180 μm), and 2.78 (gap: 250 μm). The hemolysis tended to increase at bearing gaps of greater than 100 μm due to impeller instability. When the bearing gap decreased from 30 to 20 μm, the relative NIH ratios increased significantly from 0.95 to 37.67 times (P < 0.01) due to high shear stress. We confirmed that the optimal bearing gap was determined between 30 and 100 μm in the developed blood pump for the reduction of hemolysis.

  3. Implantable centrifugal blood pump with dual impeller and double pivot bearing system: electromechanical actuator, prototyping, and anatomical studies.

    PubMed

    Bock, Eduardo; Antunes, Pedro; Leao, Tarcisio; Uebelhart, Beatriz; Fonseca, Jeison; Leme, Juliana; Utiyama, Bruno; da Silva, Cibele; Cavalheiro, Andre; Filho, Diolino Santos; Dinkhuysen, Jarbas; Biscegli, Jose; Andrade, Aron; Arruda, Celso

    2011-05-01

    An implantable centrifugal blood pump has been developed with original features for a left ventricular assist device. This pump is part of a multicenter and international study with the objective to offer simple, affordable, and reliable devices to developing countries. Previous computational fluid dynamics investigations and wear evaluation in bearing system were performed followed by prototyping and in vitro tests. In addition, previous blood tests for assessment of normalized index of hemolysis show results of 0.0054±2.46 × 10⁻³ mg/100 L. An electromechanical actuator was tested in order to define the best motor topology and controller configuration. Three different topologies of brushless direct current motor (BLDCM) were analyzed. An electronic driver was tested in different situations, and the BLDCM had its mechanical properties tested in a dynamometer. Prior to evaluation of performance during in vivo animal studies, anatomical studies were necessary to achieve the best configuration and cannulation for left ventricular assistance. The results were considered satisfactory, and the next step is to test the performance of the device in vivo.

  4. Development of Advanced Centrifugal Pumps

    SciTech Connect

    Rohatgi, U.

    2009-09-30

    A CRADA project was performed between BNL and Flowserve, California, under the auspices of Initiative for Proliferation Prevention (IPP) with the DOE support. The purpose was to jointly support a team of Russian institutes led by Kurchatov Institute to develop technology to increase operating life of centrifugal pumps. The work was performed from March 1, 2002 to September 30, 2009. The project resulted in development and validation the total cost of the sub-contract with Kurchatov Institute was $700,000, with matching fund from the industrial partner, Flowserve. The technical objective of this project is to develop advanced centrifugal pumps for the power, petroleum, chemical and water services industries by increasing the reliability of pumping equipment without a corresponding increase in life cycle cost. This major market need can be served by developing centrifugal pumps that generate only modest forces on the mechanical system even when operating under significant off-design conditions. This project is focused towards understanding the origin of hydraulic forces (both radial and axial, steady and time-dependent) and to develop design options, which reduce these forces over a broad flow range. This focus will include the force generation due to cavitation inside the pump as the operating conditions extend to low suction pressures. The results of research will reduce the inception of cavitation that leads to surface erosion and to find passive method of reducing peaks in axial thrust during whole range of flow rates.

  5. When to maintain centrifugal pumps

    SciTech Connect

    Karassik, I.J.

    1993-04-01

    Centrifugal pumps comprise critical maintenance equipment. The rationale of when to maintain them relates to a spreading tendency to contain costs in the face of tight money. Plant managers are thus entitled to a thorough analysis of whether reduced expenditures truly lower costs or actually hinder maintenance and increase costs. Absence of such an analysis hides the fact that proper and timely maintenance has a double effect: it not only reduces power consumption but also extends equipment life, and thus reduces the frequency of labor and material expenditures for scheduled or crisis maintenance. Centrifugal pump maintenance can demonstrate well the validity of this observation. The paper discusses: restoring internal clearances; real cost of renewing clearances; and monitoring clearances and pump performance.

  6. Estimation of changes in dynamic hydraulic force in a magnetically suspended centrifugal blood pump with transient computational fluid dynamics analysis.

    PubMed

    Masuzawa, Toru; Ohta, Akiko; Tanaka, Nobuatu; Qian, Yi; Tsukiya, Tomonori

    2009-01-01

    The effect of the hydraulic force on magnetically levitated (maglev) pumps should be studied carefully to improve the suspension performance and the reliability of the pumps. A maglev centrifugal pump, developed at Ibaraki University, was modeled with 926 376 hexahedral elements for computational fluid dynamics (CFD) analyses. The pump has a fully open six-vane impeller with a diameter of 72.5 mm. A self-bearing motor suspends the impeller in the radial direction. The maximum pressure head and flow rate were 250 mmHg and 14 l/min, respectively. First, a steady-state analysis was performed using commercial code STAR-CD to confirm the model's suitability by comparing the results with the real pump performance. Second, transient analysis was performed to estimate the hydraulic force on the levitated impeller. The impeller was rotated in steps of 1 degrees using a sliding mesh. The force around the impeller was integrated at every step. The transient analysis revealed that the direction of the radial force changed dynamically as the vane's position changed relative to the outlet port during one circulation, and the magnitude of this force was about 1 N. The current maglev pump has sufficient performance to counteract this hydraulic force. Transient CFD analysis is not only useful for observing dynamic flow conditions in a centrifugal pump but is also effective for obtaining information about the levitation dynamics of a maglev pump.

  7. Effect of a bearing gap on hemolytic property in a hydrodynamically levitated centrifugal blood pump with a semi-open impeller.

    PubMed

    Kosaka, Ryo; Nishida, Masahiro; Maruyama, Osamu; Yambe, Tomoyuki; Imachi, Kou; Yamane, Takashi

    2013-01-01

    We have developed a hydrodynamically levitated centrifugal blood pump with a semi-open impeller for long-term circulatory assist. The pump uses hydrodynamic bearings to enhance durability and reliability without additional displacement-sensors or control circuits. However, a narrow bearing gap of the pump has a potential for hemolysis. The purpose of this study is to develop the hydrodynamically levitated centrifugal blood pump with a semi-open impeller, and to evaluate the effect of a bearing gap on hemolytic property. The impeller levitates using a spiral-groove type thrust bearing, and a herringbone-groove type radial bearing. The pump design was improved by adopting a step type thrust bearing and optimizing the pull-up magnetic force. The pump performance was evaluated by a levitation performance test, a hemolysis test and an animal experiment. In these tests, the bearing gap increased from 1 to 63 μm. In addition, the normalized index of hemolysis (NIH) improved from 0.415 to 0.005 g/100 l, corresponding to the expansion of the bearing gap. In the animal experiment for 24 h, the plasma-free hemoglobin remained within normal ranges (<4.0 mg/dl). We confirmed that the hemolytic property of the pump was improved to the acceptable level by expanding the bearing gap greater than 60 μm.

  8. Properties of a monopivot centrifugal blood pump manufactured by 3D printing.

    PubMed

    Nishida, Masahiro; Negishi, Takumi; Sakota, Daisuke; Kosaka, Ryo; Maruyama, Osamu; Hyakutake, Toru; Kuwana, Katsuyuki; Yamane, Takashi

    2016-12-01

    An impeller the same geometry as the impeller of a commercial monopivot cardiopulmonary bypass pump was manufactured using 3D printing. The 3D-printed impeller was integrated into the pump casing of the commercially available pump to form a 3D-printed pump model. The surface roughness of the impeller, the hydraulic performance, the axial displacement of the rotating impeller, and the hemolytic properties of the 3D-printed model were measured and compared with those of the commercially available model. Although the surface roughness of the 3D-printed model was significantly larger than that of the commercially available model, the hydraulic performance of the two models almost coincided. The hemolysis level of the 3D-printed model roughly coincided with that of the commercially available model under low-pressure head conditions, but increased greatly under high-pressure head conditions, as a result of the narrow gap between the rotating impeller and the pump casing. The gap became narrow under high-pressure head conditions, because the axial thrust applied to the impeller increased with increasing impeller rotational speed. Moreover, the axial displacement of the rotating impeller was twice that of the commercially available model, confirming that the elastic deformation of the 3D-printed impeller was larger than that of the commercially available impeller. These results suggest that trial models manufactured by 3D printing can reproduce the hydraulic performance of the commercial product. However, both the surface roughness and the deformation of the trial models must be considered to precisely evaluate the hemolytic properties of the model.

  9. Implantable centrifugal pump with hybrid magnetic bearings.

    PubMed

    Bearnson, G B; Olsen, D B; Khanwilkar, P S; Long, J W; Sinnott, M; Kumar, A; Allaire, P E; Baloh, M; Decker, J

    1998-01-01

    Test methods and results of in vitro assessment of a centrifugal pump with a magnetically suspended impeller are provided. In vitro blood tests have been completed with a resulting normalized milligram index of hemolysis (NmIH) of 12.4 +/- 4.1, indicating that hemolysis is not a problem. Hydraulic characterization of the system with water has shown that a nominal pumping condition of 6 L/min at 100 mmHg was met at 2,200 rpm. Maximum clinically usable cardiac output is predicted be 10 L/min. The magnetic bearing supported impeller did not contact the housing and was shown to be stable under a variety of pumping conditions. The driving motor efficiency is 75% at the nominal condition. Finally, a description of the clinical version of the pump under development is provided.

  10. Effect of Impeller Geometry on Lift-Off Characteristics and Rotational Attitude in a Monopivot Centrifugal Blood Pump.

    PubMed

    Nishida, Masahiro; Nakayama, Kento; Sakota, Daisuke; Kosaka, Ryo; Maruyama, Osamu; Kawaguchi, Yasuo; Kuwana, Katsuyuki; Yamane, Takashi

    2016-06-01

    The effect of the flow path geometry of the impeller on the lift-off and tilt of the rotational axis of the impeller against the hydrodynamic force was investigated in a centrifugal blood pump with an impeller supported by a single-contact pivot bearing. Four types of impeller were compared: the FR model with the flow path having both front and rear cutouts on the tip, the F model with the flow path having only a front cutout, the R model with only a rear cutout, and the N model with a straight flow path. First, the axial thrust and the movement about the pivot point, which was loaded on the surface of the impeller, were calculated using computational fluid dynamics (CFD) analysis. Next, the lift-off point and the tilt of the rotational axis of the impeller were measured experimentally. The CFD analysis showed that the axial thrust increased gently in the FR and R models as the flow rate increased, whereas it increased drastically in the F and N models. This difference in axial thrust was likely from the higher pressure caused by the smaller circumferential velocity in the gap between the top surface of the impeller and the casing in the FR and R models than in the F and N models, which was caused by the rear cutout. These results corresponded with the experimental results showing that the impellers lifted off in the F and N models as the flow rate increased, whereas it did not in the FR and R models. Conversely, the movement about the pivot point increased in the direction opposite the side with the pump outlet as the flow rate increased. However, the tilt of the rotational axis of the impeller, which oriented away from the pump outlet, was less than 0.8° in any model under any conditions, and was considered to negligibly affect the rotational attitude of the impeller. These results confirm that a rear cutout prevents lift-off of the impeller caused by a decrease in the axial thrust.

  11. Real-Time Observation of Thrombus Growth Process in an Impeller of a Hydrodynamically Levitated Centrifugal Blood Pump by Near-Infrared Hyperspectral Imaging.

    PubMed

    Sakota, Daisuke; Murashige, Tomotaka; Kosaka, Ryo; Fujiwara, Tatsuki; Nishida, Masahiro; Maruyama, Osamu

    2015-08-01

    Understanding the thrombus formation in cardiovascular devices such as rotary blood pumps is the most important issue in developing more hemocompatible devices. The objective of this study was to develop a hyperspectral imaging (HSI) method to visualize the thrombus growth process within a rotary blood pump and investigate the optical properties of the thrombus. An in vitro thrombogenic test was conducted using fresh porcine blood and a specially designed hydrodynamically levitated centrifugal blood pump with a transparent bottom. The pump rotating at 3000 rpm circulated the blood at 1.0 L/min. The bottom surface of the pump was illuminated with white light pulsed at the same frequency as the pump rotation, and the backward-scattered light was imaged using the HSI system. Using stroboscopic HSI and an image construction algorithm, dynamic spectral imaging at wavelengths ranging from 608 to 752 nm within the rotating pump was achieved. After completing the experiment, we collected the red thrombus formed in the pump impeller and quantified the thrombus hemoglobin concentration (Hbthrombus ). The spectrum changed around the center of the impeller, and the area of change expanded toward the impeller flow path. The shape corresponded approximately to the shape of the thrombus. The spectrum change indicated that the light scattering derived from red blood cells decreased. The Hbthrombus was 4.7 ± 1.3 g/dL versus a total hemoglobin of 13 ± 0.87 g/dL. The study revealed that Hbthrombus was reduced by the surrounding blood flow.

  12. Engineering Aspects in Blood Pump Development

    NASA Technical Reports Server (NTRS)

    Golding, Leonard; Veres, Joseph P.

    1997-01-01

    NASA turbomachinery computer codes assisted in the design of the Cleveland Clinic Foundation's centrifugal bladed blood pump. The codes were originally developed for the aerospace industry, but are applicable to the blood pump because of a high degree of synergy with this application. Traditional turbomachinery design criteria were used in the design of the blood pump centrifugal impeller and volute casing. The fluid dynamic performance of the blood pump is meeting the engineering design goals of flow rate and pressure rise.

  13. Avoid self-priming centrifugal pump

    SciTech Connect

    Reeves, G.G.

    1987-01-01

    The self-priming horizontal centrifugal pump becomes known to its operator either as a good pump or a bad pump. The latter is usually replaced by another type of pump, even though a properly specified self-priming centrifugal pump might have been a good choice. Use of the guidelines described in this article are intended to help in the purchase and installation of a good pump. Self-priming centrifugal pumps are used for removing liquids from below grade sumps or pits that may also contain solids, fibers and/or muck. Alternate pumps for this service include submersible pumps, vertical turbine pumps and positive displacement pumps. These alternate pumps do not pass solid particles as large as self-priming pumps do without damage. Positive displacement pumps are not normally cost-effective when pumping liquid at rates in excess of 500 gallons per minute in low-head applications. Vertical and submersible pumps must be removed when cleaning of the pump is required. Self-priming pumps are easily cleaned by opening the access plates without moving the pump; and they cost less than the other types.

  14. 3. Interior view of centrifugal pump house showing pumps and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. Interior view of centrifugal pump house showing pumps and engines, looking W. - Laurel Valley Sugar Plantation, Drainage Plant, 2 Miles South of Thibodaux on State Route 308, Thibodaux, Lafourche Parish, LA

  15. Comparative hemolysis study of clinically available centrifugal pumps.

    PubMed

    Naito, K; Suenaga, E; Cao, Z L; Suda, H; Ueno, T; Natsuaki, M; Itoh, T

    1996-06-01

    Centrifugal pumps have become important devices for cardiopulmonary bypass and circulatory assistance. Five types of centrifugal pumps are clinically available in Japan. To evaluate the blood trauma caused by centrifugal pumps, a comparative hemolysis study was performed under identical conditions. In vitro hemolysis test circuits were constructed to operate the BioMedicus BP-80 (Medtronic, BioMedicus), Sarns Delphin (Sarns/3M Healthcare), Isoflow (St. Jude Medical [SJM]), HPM-15 (Nikkiso), and Capiox CX-SP45 (Terumo). The hemolysis test loop consisted of two 1.5 m lengths of polyvinyl chloride tubing with a 3/8-inch internal diameter, a reservoir with a sampling port, and a pump head. All pumps were set to flow at 6 L/min against the total pressure head of 120 mm Hg. Experiments were conducted simultaneously for 6 h at room temperature (21 degrees C) with fresh bovine blood. Blood samples for plasma-free hemoglobin testing were taken, and the change in temperature at the pump outlet port was measured during the experiment. The mean pump rotational speeds were 1,570, 1,374, 1,438, 1,944, and 1,296 rpm, and the normalized indexes of hemolysis were 0.00070, 0.00745, 0.00096, 0.00066, 0.00090 g/100 L for the BP-80, Sarns, SJM, Nikkiso, and Terumo pumps, respectively. The change in temperature at the pump outlet port was the least for the Nikkiso pump (1.8 degrees C) and the most with the SJM pump (3.8 degrees C). This study showed that there is no relationship between the pump rotational speed (rpm) and the normalized index of hemolysis in 5 types of centrifugal pumps. The pump design and number of impellers could be more notable factors in blood damage.

  16. Development of a disposable maglev centrifugal blood pump intended for one-month support in bridge-to-bridge applications: in vitro and initial in vivo evaluation.

    PubMed

    Someya, Takeshi; Kobayashi, Mariko; Waguri, Satoshi; Ushiyama, Tomohiro; Nagaoka, Eiki; Hijikata, Wataru; Shinshi, Tadahiko; Arai, Hirokuni; Takatani, Setsuo

    2009-09-01

    MedTech Dispo, a disposable maglev centrifugal blood pump with two degrees of freedom magnetic suspension and radial magnetic coupling rotation, has been developed for 1-month extracorporeal circulatory support. As the first stage of a two-stage in vivo evaluation, 2-week evaluation of a prototype MedTech Dispo was conducted. In in vitro study, the pump could produce 5 L/min against 800 mm Hg and the normalized index of hemolysis was 0.0054 +/- 0.0008 g/100 L. In in vivo study, the pump, with its blood-contacting surface coated with biocompatible 2-methacryloyloxyethyl phosphorylcholine polymer, was implanted in seven calves in left heart bypass. Pump performance was stable with a mean flow of 4.49 +/- 0.38 L/min at a mean speed of 2072.1 +/- 64.5 rpm. The maglev control revealed its stability in rotor position during normal activity by the calves. During 2 weeks of operation in two calves which survived the intended study period, no thrombus formation was seen inside the pump and levels of plasma free hemoglobin were maintained below 4 mg/dL. Although further experiments are required, the pump demonstrated the potential for sufficient and reliable performance and biocompatibility in meeting the requirements for cardiopulmonary bypass and 1-week circulatory support.

  17. Development of a novel centrifugal pump: magnetic rotary pump.

    PubMed

    Naganuma, S; Yambe, T; Sonobe, T; Kobayashi, S; Nitta, S

    1997-07-01

    The rotational axis of the centrifugal pump has some associated problems such as blood destruction and sealing between the axis and pump housing. To improve upon these deficits we have developed a new type of blood pump, the magnetic rotary pump (MRP). The MRP has an original design with no rotational axis and no impellers. We made a prototype MRP and examined its hemodynamics in mock circulation. The prototype MRP flow rate is only 1.0 L/min with an afterload of 30 mm Hg, and we have made some modifications in the size and drive mechanisms from these results. The modified MRP can achieve high flow rates and rotational speeds (6.0 L/min with an afterload of 100 mm Hg, 2,000 rpm) in a mock circuit, and the modified MRP was used for left heart assistance in an acute animal experiment. The MRP could maintain the hemodynamics of an anesthetized adult goat. These results suggest that the MRP needs to be improved in several areas, but the MRP may be useful as a blood pump.

  18. Development of a disposable magnetically levitated centrifugal blood pump (MedTech Dispo) intended for bridge-to-bridge applications--two-week in vivo evaluation.

    PubMed

    Nagaoka, Eiki; Someya, Takeshi; Kitao, Takashi; Kimura, Taro; Ushiyama, Tomohiro; Hijikata, Wataru; Shinshi, Tadahiko; Arai, Hirokuni; Takatani, Setsuo

    2010-09-01

    Last year, we reported in vitro pump performance, low hemolytic characteristics, and initial in vivo evaluation of a disposable, magnetically levitated centrifugal blood pump, MedTech Dispo. As the first phase of the two-stage in vivo studies, in this study we have carried out a 2-week in vivo evaluation in calves. Male Holstein calves with body weight of 62.4–92.2 kg were used. Under general anesthesia, a left heart bypass with a MedTech Dispo pump was instituted between the left atrium and the descending aorta via left thoracotomy. Blood-contacting surface of the pump was coated with a 2-methacryloyloxyethyl phosphorylcholine polymer. Post-operatively, with activated clotting time controlled at 180–220 s using heparin and bypass flow rate maintained at 50 mL/kg/min, plasma-free hemoglobin (Hb), coagulation, and major organ functions were analyzed for evaluation of biocompatibility. The animals were electively sacrificed at the completion of the 2-week study to evaluate presence of thrombus inside the pump,together with an examination of major organs. To date, we have done 13 MedTech Dispo implantations, of which three went successfully for a 2-week duration. In these three cases, the pump produced a fairly constant flow of 50 mL/Kg/min. Neurological disorders and any symptoms of thromboembolism were not seen. Levels of plasma-free Hb were maintained very low. Major organ functions remained within normal ranges. Autopsy results revealed no thrombus formation inside the pump. In the last six cases, calves suffered from severe pneumonia and they were excluded from the analysis. The MedTech Dispo pump demonstrated sufficient pump performance and biocompatibility to meet requirements for 1-week circulatory support. The second phase (2-month in vivo study) is under way to prove the safety and efficacy of MedTech Dispo for 1-month applications.

  19. New generation extracorporeal membrane oxygenation with MedTech Mag-Lev, a single-use, magnetically levitated, centrifugal blood pump: preclinical evaluation in calves.

    PubMed

    Fujiwara, Tatsuki; Nagaoka, Eiki; Watanabe, Taiju; Miyagi, Naoto; Kitao, Takashi; Sakota, Daisuke; Mamiya, Taichi; Shinshi, Tadahiko; Arai, Hirokuni; Takatani, Setsuo

    2013-05-01

    We have evaluated the feasibility of a newly developed single-use, magnetically levitated centrifugal blood pump, MedTech Mag-Lev, in a 3-week extracorporeal membrane oxygenation (ECMO) study in calves against a Medtronic Bio-Pump BPX-80. A heparin- and silicone-coated polypropylene membrane oxygenator MERA NHP Excelung NSH-R was employed as an oxygenator. Six healthy male Holstein calves with body weights of about 100 kg were divided into two groups, four in the MedTech group and two in the Bio-Pump group. Under general anesthesia, the blood pump and oxygenator were inserted extracorporeally between the main pulmonary artery and the descending aorta via a fifth left thoracotomy. Postoperatively, both the pump and oxygen flow rates were controlled at 3 L/min. Heparin was continuously infused to maintain the activated clotting time at 200-240 s. All the MedTech ECMO calves completed the study duration. However, the Bio-Pump ECMO calves were terminated on postoperative days 7 and 10 because of severe hemolysis and thrombus formation. At the start of the MedTech ECMO, the pressure drop across the oxygenator was about 25 mm Hg with the pump operated at 2800 rpm and delivering 3 L/min flow. The PO2 of the oxygenator outlet was higher than 400 mm Hg with the PCO2 below 45 mm Hg. Hemolysis and thrombus were not seen in the MedTech ECMO circuits (plasma-free hemoglobin [PFH] < 5 mg/dL), while severe hemolysis (PFH > 20 mg/dL) and large thrombus were observed in the Bio-Pump ECMO circuits. Plasma leakage from the oxygenator did not occur in any ECMO circuits. Three-week cardiopulmonary support was performed successfully with the MedTech ECMO without circuit exchanges. The MedTech Mag-Lev could help extend the durability of ECMO circuits by the improved biocompatible performances.

  20. Motor current waveforms as an index for evaluation of native cardiac function during left ventricular support with a centrifugal blood pump.

    PubMed

    Kikugawa, D

    2001-09-01

    Control of ventricular assist devices (VADs) for native heart preservation should be attempted, and it could be one strategy for dealing with the shortage of donors in the future. In the application of a nonpulsatile blood pump for ventricular assistance from its apex to the aorta, the bypass flow and hence motor current of the pumps change in response to the ventricular pressure change. Utilizing these intrinsic characteristics of the continuous flow pumps, this study investigated whether or not motor current could be used as an index for continuous monitoring of native cardiac function. In Study 1, a centrifugal blood pump (CFP) VAD was installed between the apex and descending aorta of a mock circulatory loop. In this model, a baseline with a preload of 10 mm Hg, afterload of 40 mm Hg, and left ventricular (LV) systolic pressure of 40 mm Hg was used. The pump rpm were fixed at 1,300, 1,500, and 1,700, and LV systolic pressure was increased up to 140 mm Hg by a step of 20 mm Hg while observing the changes in LV pressure, motor current, pump flow, and aortic pressure. In Study 2, in vivo experiments were performed using 5 sheep. A left heart bypass model was created using a centrifugal pump from the ventricular apex to the descending aorta. The LV pressure was varied through administration of dopamine while observing the changes in LV pressure, pump flow, motor current, and aortic pressure at 1,500 and 1,700 rpm. An excellent correlation was observed both in vitro and in vivo studies in the relationship between motor current and LV pressure. In Study 1, the correlation coefficients were 0.77, 0.92, and 0.99 for 1,300, 1,500, and 1,700 rpm, respectively. In Study 2, they were 0.90 (Animal 1), 0.82 (Animal 2), 0.89 (Animal 3), 0.93 (Animal 4), and 0.70 (Animal 5) respectively for 1,500 rpm, and 0.94 (Animal 2), 0.85 (Animal 3), 0.94 (Animal 4), and 0.89 (Animal 5) respectively, for 1,700 rpm. The relationship between motor current and pump flow and LV pressure

  1. Optimum design for LRE centrifugal pumps

    NASA Astrophysics Data System (ADS)

    Zhu, Zuchao; Zhang, Guoqian; Sun, Jiren

    1995-05-01

    We set up a mathematical model to predict low specific speed liquid rocket engine (LRE) centrifugal pump unit performance. Using the model in question, performance predictions were carried out for 10 types of LRE centrifugal pumps. Relative errors between experimental values and predicted values associated with efficiency and lift were all within 4%. Using the model in question, design optimization with efficiency as the target function was carried out on AM-7H and O pumps as well as AM-1R pumps and AM-50 pumps. Results clearly show that, with a presupposition of surety systems possessing high vapor corrosion characteristics, the efficiencies of these four types of pumps can be respectively raised 6.5%, 5.22%, 5.2%, and 4.41%.

  2. Assessing the calf pulmonary function during a long-term biventricular assist device study with a centrifugal blood pump.

    PubMed

    Nonaka, Kenji; Linneweber, Joerg; Ichikawa, Seiji; Kawahito, Shinji; Motomura, Tadashi; Ishitoya, Hiroshi; Oestmann, Daniel; Glueck, Julia; Nosé, Yukihiko

    2002-11-01

    Pulmonary congestion due to inappropriate pump flow management is one major problem necessary to avoid during long-term biventricular assist device (BVAD) implantation. Our objective was to assess the effects of pulmonary arterial flow rate and flow rates of both (right and left) bypass pumps. Six healthy calves, which had been implanted with a BVAD system, were selected for this retrospective study. Pulmonary artery flows, both pump flow rates, oxygen saturation of the arterial blood, and pulmonary arterial pressures were assessed as parameters of pulmonary function as was routine clinical evaluation of respiratory rate and character and chest auscultation. The average pulmonary artery flow rate (PAF), systolic pressure of pulmonary artery (sPAP), and oxygen saturation were 148.8 ml/kg per min, 35.1 mm Hg, and 95.3%, respectively. Pulmonary dysfunction occurred in one case, in which the mean PAF, sPAP, and oxygen saturation were 169 ml/kg per min, 66.1 mm Hg, and 90.9%, respectively. The ratio for the right/left pump flow rate (R/L ratio) for the case having pulmonary dysfunction was 1.57 even though the ratio for the other cases was less than 1. Maintaining an R/L ratio less than 1 and/or PAF less than 160 ml/kg per min and PAP less than 50 mm Hg is recommended as the initial conditions to target to avoid pulmonary dysfunction during a BVAD implantation with a beating heart condition.

  3. A comparative study between flow visualization and computational fluid dynamic analysis for the sun medical centrifugal blood pump.

    PubMed

    Yamane, Takashi; Miyamoto, Yusuke; Tajima, Koki; Yamazaki, Kenji

    2004-05-01

    Flow visualization experiments and computational fluid dynamic (CFD) analyses were performed and the results were compared to clarify the detailed fluid dynamic characteristics for the prototype design of a centrifugal pump, namely, an implantable ventricular assist system from Sun Medical, whose hemocompatibility was previously demonstrated in a series of animal experiments. The flow visualization was conducted with particle tracking velocimetry, and the CFD analysis was performed with STAR-CD software. The findings were as follows: (1). There were no flow separations around the curved open impeller. (2). Antithrombogenic design concepts for the inducer and the vane-shaft clearance were effective in producing axial velocity along the shaft surface and generat-ing suitable shear rates against the stationary fluid. (3). Unsteady vortex shedding in the outlet, which adversely affected the fluid dynamic efficiency, was observed clearly by flow visualization. Comparison of velocity distribution measured by flow visualization and CFD analysis showed reasonably good correlation. Our findings indicate that the impeller is suitable for an implantable artificial heart. The techniques of flow visualization and CFD analysis are complementary evaluation tools in research and development efforts.

  4. A centrifugal pump used as a turbine

    SciTech Connect

    Yap, F.U.; Lasnier, F. )

    1990-06-01

    Due to the high cost of putting up conventional turbines for micro-hydropower installations, Inversin (1986) mentioned the use of pumps being run in reverse to function as turbines. Typical performance characteristics of a centrifugal pump running as a turbine are shown in a figure. Pump/turbine maximum efficiencies tend to occur over a wide range of capacity. This study is concerned with the use of non-conventional hydro equipment, locally and readily available for small rural electricity applications. Here, the operation of a small centrifugal pump, used as a turbine and coupled with a conventional car alternator, was investigated. The article reveals a method for evaluating not only this but other small generating systems for appropriateness to the conditions of the site.

  5. Centrifugal Force Based Magnetic Micro-Pump Driven by Rotating Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Kim, S. H.; Hashi, S.; Ishiyama, K.

    2011-01-01

    This paper presents a centrifugal force based magnetic micro-pump for the pumping of blood. Most blood pumps are driven by an electrical motor with wired control. To develop a wireless and battery-free blood pump, the proposed pump is controlled by external rotating magnetic fields with a synchronized impeller. Synchronization occurs because the rotor is divided into multi-stage impeller parts and NdFeB permanent magnet. Finally, liquid is discharged by the centrifugal force of multi-stage impeller. The proposed pump length is 30 mm long and19 mm in diameter which much smaller than currently pumps; however, its pumping ability satisfies the requirement for a blood pump. The maximum pressure is 120 mmHg and the maximum flow rate is 5000ml/min at 100 Hz. The advantage of the proposed pump is that the general mechanical problems of a normal blood pump are eliminated by the proposed driving mechanism.

  6. Initial clinical experience with the Baylor-Nikkiso centrifugal pump.

    PubMed

    Ohtsubo, S; Naito, K; Matsuura, M; Kawahito, K; Shimono, T; Makinouchi, K; Tasai, K; Ohara, Y; Damm, G; Glueck, J

    1995-07-01

    Recently, a newly developed centrifugal pump, the Baylor-Nikkiso pump, was approved for clinical use in the United States. This pump is the most compact centrifugal pump with a priming volume of only 25 ml. Although it is small, this pump can provide a flow of 4 L/min against a total pressure head of 300 mm Hg at 3,000 rpm. In vitro and in vivo validation of the Baylor-Nikkiso pump has proved that this pump could effectively reduce blood trauma even under high total head pressure. In addition, 48-h durability tests with biventricular bypass using calves verified the reliability of shaft sealing and antithrombogenicity. Clinical trials of the Baylor-Nikkiso pumps have been initiated in our department. This pump provides flows of 60-70 ml/kg/min with stable hemodynamic conditions. No leakage of thrombus formation was observed. The results of the initial clinical experience of the Baylor-Nikkiso pump suggest that it is suitable for cardiopulmonary bypass surgery.

  7. Centrifugal Pump Experiment for Chemical Engineering Undergraduates

    ERIC Educational Resources Information Center

    Vanderslice, Nicholas; Oberto, Richard; Marrero, Thomas R.

    2012-01-01

    The purpose of this paper is to describe a Centrifugal Pump Experiment that provided an experiential learning experience to chemical engineering undergraduates at the University of Missouri in the spring of 2010 in the Unit Operations Laboratory course. Lab equipment was used by senior students with computer-based data and control technology. In…

  8. At 1050 Gallery, Block 12, two centrifugal pumps, Buffalo Pumps, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    At 1050 Gallery, Block 12, two centrifugal pumps, Buffalo Pumps, Buffalo, NY, driven by Allis Chalmers motors (size 3 HSO, head 230, 120 cpm, 1750, rpm, Impulse dia. 15) installed in the 1960s and used for water-cooling system for 230-kv cable; the cables have been removed and the pumps are not currently used. - Columbia Basin Project, Grand Coulee Dam & Franklin D. Roosevelt Lake, Across Columbia River, Southeast of Town of Grand Coulee, Grand Coulee, Grant County, WA

  9. Optimal design of the hydrodynamic multi-arc bearing in a centrifugal blood pump for the improvement of bearing stiffness and hemolysis level.

    PubMed

    Yasui, Kazuya; Kosaka, Ryo; Nishida, Masahiro; Maruyama, Osamu; Kawaguchi, Yasuo; Yamane, Takashi

    2013-09-01

    The purpose of the present study is to establish an optimal design of the multi-arc hydrodynamic bearing in a centrifugal blood pump for the improvement of bearing stiffness and hemolysis level. The multi-arc bearing was designed to fulfill the required specifications: (i) ensuring the uniform bearing stiffness for various bearing angles; (ii) ensuring a higher bearing stiffness than the centrifugal force to prevent impeller whirl; and (iii) adjusting the bearing clearance as much as possible to reduce hemolysis. First, a numerical analysis was performed to optimize three design parameters of the multi-arc bearing: number of arcs N, bearing clearance C, and groove depth H. To validate the accuracy of the numerical analysis, the impeller trajectories for six pump models were measured. Finally, an in vitro hemolysis test was conducted to evaluate the hemolytic property of the multi-arc bearing. As a result of the numerical analysis, the optimal parameter combination was determined as follows: N=4, C=100 μm, and H ≥ 100 μm. In the measurements of the impeller trajectory, the optimal parameter combination was found to be as follows: N=4, C=90 μm, and H=100 μm. This result demonstrated the high reliability of the numerical analysis. In the hemolysis test, the parameter combination that achieved the smallest hemolysis was obtained as follows: N=4, C=90 μm, and H=100 μm. In conclusion, the multi-arc bearing could be optimized for the improvement of bearing stiffness and hemolysis level.

  10. Clinical evaluation of the centrifugal pump in open heart surgery: a comparative study of different pumps.

    PubMed

    Takarabe, K; Yoshikai, M; Murayama, J; Hamada, M; Ito, T

    1997-07-01

    The centrifugal pump is now widely used in open heart surgery for its clinical benefits related to the blood elements and the coagulation system. The purpose of this study was to compare the clinical performances of and the outcomes offered by 4 types of centrifugal pumps. For each pump, we investigated the effects on the blood elements, coagulation system, complements, and immunoglobulins during open heart surgery. Four types of centrifugal pumps were used: the HPM-15 (Nikkiso Co.), the Capiox (Terumo Co.), the Lifestream (St. Jude Medical Co.), and the BP-80 (Medtronic, BioMedicus Co.). The platelet count, lactate dehydrogenase (LDH), antithrombin III (AT III), thrombin-antithrombin complex (TAT), complements (C3, C4, and CH50), and immunoglobulins (IgG, IgA, and IgM) were measured before and after cardiopulmonary bypass (CPB). The platelet count was decreased more significantly by the HPM-15 than by any of the other pumps. The other parameters showed no difference among the 4 pumps. In clinical use, each of the 4 types of centrifugal pumps was safe.

  11. High efficiency, variable geometry, centrifugal cryogenic pump

    SciTech Connect

    Forsha, M.D.; Nichols, K.E.; Beale, C.A.

    1994-12-31

    A centrifugal cryogenic pump has been developed which has a basic design that is rugged and reliable with variable speed and variable geometry features that achieve high pump efficiency over a wide range of head-flow conditions. The pump uses a sealless design and rolling element bearings to achieve high reliability and the ruggedness to withstand liquid-vapor slugging. The pump can meet a wide range of variable head, off-design flow requirements and maintain design point efficiency by adjusting the pump speed. The pump also has features that allow the impeller and diffuser blade heights to be adjusted. The adjustable height blades were intended to enhance the pump efficiency when it is operating at constant head, off-design flow rates. For small pumps, the adjustable height blades are not recommended. For larger pumps, they could provide off-design efficiency improvements. This pump was developed for supercritical helium service, but the design is well suited to any cryogenic application where high efficiency is required over a wide range of head-flow conditions.

  12. Centrifugal pump inlet pressure site affects measurement.

    PubMed

    Augustin, Simon; Horton, Alison; Butt, Warwick; Bennett, Martin; Horton, Stephen

    2010-09-01

    During extracorporeal life support (ECLS), blood is exposed to a myriad of unphysiological factors that can affect outcome. One aspect of this is the sub-atmospheric pressure generated by the ECLS pump and imparted to blood elements along the pump inlet line. This pressure can be measured on the inlet line close to the pump head by adding a connector, or at the venous cannula connection site. We compared the two measurement sites located at both points; between the venous cannula-inlet tubing and inlet tubing-pump, with a range of cannulae and flows. We also investigated the effects on inlet pressure from pump afterload and increasing inlet tubing length.

  13. Hydrodynamic performance and heat generation by centrifugal pumps.

    PubMed

    Ganushchak, Y; van Marken Lichtenbelt, W; van der Nagel, T; de Jong, D S

    2006-11-01

    For over a century, centrifugal pumps (CP) have been used in various applications, from large industrial pumps to flow pumps for aquariums. However, the use of CP as blood pumps has a rather short history. Consequently, the hydraulic performance data for a blood CP are limited. The aim of our investigation was to study the hydraulic performance and the heat generation of three commercially available CP: Bio-Medicus Bio-Pump BP80 (Medtronic), Rotaflow (Jostra Medizintechnik), and DeltaStream DP2 (MEDOS Medizintechnik AQ). The study was performed using a circuit primed with a water-glycerin mixture with a dynamic viscosity of 0.00272 pa/s. Pressure-flow curves were obtained by a stepwise stagnation of the pump outlet or inlet. The temperature changes were observed using ThermaCAM SC2000 (Flir Systems). The pumps' performance in close to clinical conditions ('operating region') was analysed in this report. The 'operating region' in the case of the BP80 is positioned around the pressure-flow curve at a pump speed of 3000 rpm. In the case of the Rotaflow, the 'operating region' was between the pump pressure-flow curves at a speed of 3000 and 4000 rpm, and the DP2 was found between 7000 and 8000 rpm. The standard deviation of mean pressure through the pump was used to characterise the stability of the pump. In experiments with outlet stagnation, the BP80 demonstrated high negative association between flow and pressure variability (r = -0.68, p < 0.001). In experiments with the DP2, this association was positive (r = 0.68, p < 0.001). All pumps demonstrated significantly higher variability of pressure in experiments with inlet stagnation in comparison to the experiments with outlet stagnation. The rise of relative temperature in the inlet of a pump was closely related to the flow rate. The heating of fluid was more pronounced in the 'zero-flow' mode, especially in experiments with inlet stagnation. In summary, (1) the 'zero-flow' regime, which is described in the manuals

  14. Potential flow through centrifugal pumps and turbines

    NASA Technical Reports Server (NTRS)

    Sorensen, E

    1941-01-01

    The methods of conformal transformation up to the present have been applied to the potential flows in the rotation of solid bodies only to a limited extent. This report deals with aspects of centrifugal pumps and turbines such as: the complex potential for rotation, potential for the flow due to the blade rotation, velocities at the blade tip, comparison with "infinite number of blades," and a variable number of blades.

  15. Flow Analysis of the Cleveland Clinic Centrifugal Pump

    NASA Technical Reports Server (NTRS)

    Veres, Joseph P.; Golding, Leonard A. R.; Smith, William A.; Horvath, David; Medvedev, Alexander

    1997-01-01

    An implantable ventricular assist rotordynamic blood pump is being developed by the Cleveland Clinic Foundation in cooperation with the NASA Lewis Research Center. At the nominal design condition, the pump provides blood flow at the rate of 5 liters per minute at a pressure rise of 100 mm of mercury and a rotative speed of 3000 RPM. Bench testing of the centrifugal pump in a water/glycerin mixture has provided flow and pressure data at several rotative speeds. A one-dimensional empirical based pump flow analysis computer code developed at NASA Lewis Research Center has been used in the design process to simulate the flow in the primary centrifugal pump stage. The computer model was used to size key impeller and volute geometric parameters that influence pressure rise and flow. Input requirements to the computer model include a simple representation of the pump geometry. The model estimates the flow conditions at the design and at off-design operating conditions at the impeller leading and trailing edges and the volute inlet and exit. The output from the computer model is compared to flow and pressure data obtained from bench testing.

  16. 23. TEMPORARY CENTRIFUGAL PUMP. NOTE CHAPMAN HYDRAULICOPERATED VALVE FOR LATER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. TEMPORARY CENTRIFUGAL PUMP. NOTE CHAPMAN HYDRAULIC-OPERATED VALVE FOR LATER CONNECTION OF ENGINE PUMP ENG TO DISCHARGE HEADER. - Lakeview Pumping Station, Clarendon & Montrose Avenues, Chicago, Cook County, IL

  17. Hemodynamic effects of pressure-volume relation in the atrial contraction model on the total artificial heart using centrifugal blood pumps.

    PubMed

    Shiga, Takuya; Kuroda, Takehito; Tsuboko, Yusuke; Miura, Hidekazu; Shiraishi, Yasuyuki; Yambe, Tomoyuki

    2013-01-01

    Hemodynamic effects of atrial contraction with centrifugal pump type total artificial heart is unknown. In this study, we simulated an atrial contraction in a mock model. By the driving condition with higher pressure in the mock atrial model, the load during atrial contraction increased. Based on these findings, we examined atrial contraction in the animal using adult goats. Prior to the measurement, we installed a centrifugal-type ventricular assist device (VADs), and then clamped both ventricles. We measured the hemodynamic data without ventricular contractile functions in order to obtain the effect of atrial contraction on hemodynamics under the condition of the total artificial heart (TAH) circulatory support model. We could estimate the heart rate by revolution number and voltage of pumps. There might be a possibility that we could regulate autonomic nervous response with the control of cardiac output.

  18. Centrifugal pumps: which suction specific speeds are acceptable

    SciTech Connect

    Hallam, J.L.

    1982-04-01

    Suction specific speed is an important consideration when purchasing or analyzing centrifugal pumps. There is a direct correlation between this parameter, pump reliability and maintenance expenses. This article demonstrates that in a large Gulf Coast oil refinery, centrifugal pumps with a suction specific speed greater than 11,000 failed at a frequency nearly twice that of centrifugal pumps with suction specific speed less than 11,000. This study consisted primarily of hydrocarbon pumps with an average horsepower of 150 hp. Results may vary some from those found if high energy water pumps are studied. 5 refs.

  19. Haemolysis during cardiopulmonary bypass: an in vivo comparison of standard roller pumps, nonocclusive roller pumps and centrifugal pumps.

    PubMed

    Hansbro, S D; Sharpe, D A; Catchpole, R; Welsh, K R; Munsch, C M; McGoldrick, J P; Kay, P H

    1999-01-01

    Cardiopulmonary bypass (CPB) involves the use of either an occlusive roller pump or centrifugal pump. Damage to blood elements, including haemolysis, may arise from occlusion when using a roller pump; the appropriate degree of occlusion has not yet been determined scientifically. Centrifugal and nonocclusive roller pumps are reputed to reduce haemolysis. The objective of this study was to compare haemolysis caused by a standard roller pump with a dynamically set nonocclusive roller pump and with a centrifugal pump. We prospectively randomized 60 patients undergoing routine coronary artery surgery into three groups: standard roller pump (STD, n = 20), dynamically set roller pump (DYN, n = 20), or centrifugal pump (CEN, n = 20). The level of plasma free haemoglobin (FHb) was measured preoperatively, and the rate of formation of FHb (in mg/dl/min) was determined at the end of the ischaemic phase and at the end of CPB. Cardiotomy suction blood was isolated for the ischaemic phase and returned before the end of CPB. It was found that there were no differences between the groups in demographic or operative variables. The rate of formation of FHb at the end of the ischaemic phase was similar for all groups (STD 0.108 +/- 0.10, DYN 0.117 +/- 0.08, CEN 0.129 +/- 0.07). At the end of CPB, after return of the cardiotomy suction blood, there was a significant (< 0.001) increase in the rate of formation of FHb in all groups. The increase was similar for each of the groups (STD 0.424 +/- 0.17, DYN 0.481 +/- 0.20, CEN 0.471 +/- 0.18). We conclude that the rates of haemolysis are similar for each of the pump types, and no benefit is conferred by the use of either a dynamically set roller pump or a centrifugal pump compared with the standard roller pump. The return of the cardiotomy suction blood to the circulation is the principal source of plasma free haemoglobin.

  20. Platelet function and hemolysis in centrifugal pumps: in vitro investigations.

    PubMed

    Steines, D; Westphal, D; Göbel, C; Reul, H; Rau, G

    1999-08-01

    The effects of centrifugal pumps on blood components other than erythrocytes, namely platelets and their interaction with the coagulation system, are not very well known. In a comparative study with three centrifugal pumps (BioMedicus BP-80, St. Jude Isoflow, and Sarns Delphin) and the Stockert roller pump hemolysis, platelet counts, thromboplastin and partial thromboplastin times, as well as resonance thrombography (RTG) parameters for the assessment of platelet and coagulation function were evaluated in vitro. Normalized indices of hemolysis (NIH) with ACD anticoagulation after 360 minutes were 0.008+/-0.004 (Isoflow), 0.018+/-0.017 (BP-80), 0.085+/-0.051 (Delphin), and 0.049+/-0.010 g/1001 (roller pump). Plasmatic coagulation was activated in all circuits. Platelet function was severely inhibited by the BP-80, indicated by increase in RTG platelet time to 358%+/-150% of initial values compared to 42%+/-29% (Isoflow), 40%+/-20% (Delphin), and 12%+/-10% (roller pump). Fibrin polymerization was affected similarly. The large surface area of the BP-80 leads to an extensive activation of platelets and plasminogen.

  1. Prediction of performance of centrifugal pumps during starts under pressure

    NASA Technical Reports Server (NTRS)

    Rostafinski, W.

    1969-01-01

    Method which calculates start-up characteristics of centrifugal pumps reveals a capacity to predict pressure drop characteristics of pumps with vaned diffusers. Calculations are based on pump geometry, design-point flow, speed, and pressure rise, and the pump characteristic within range of approximately ten percent of the design-point flow.

  2. Rotordynamic forces on centrifugal pump impellers

    NASA Technical Reports Server (NTRS)

    Franz, R.; Arndt, N.; Caughey, T. K.; Brennen, C. E.; Acosta, A. J.

    1987-01-01

    The asymmetric flow around an impeller in a volute exerts a force upon the impeller. To study the rotordynamic force on an impeller which is vibrating around its machine axis of rotation, the impeller, mounted on a dynamometer, is made to whirl in a circular orbit within the volute. The measured force is expressed as the sum of a steady radial force and an unsteady force due to the eccentric motion of the impeller. These forces were measured in separate tests on a centrifugal pump with radically increased shroud clearance, a two-dimensional impeller, and an impeller with an inducer, the impeller of the HPOTP (High Pressure Oxygen Turbopump) of the SSME (Space Shuttle Main Engine). In each case, a destabilizing force was observed over a region of positive whirl.

  3. A seal-less centrifugal pump (Baylor Gyro Pump) for application to long-term circulatory support.

    PubMed

    Minato, N; Sakuma, I; Sasaki, T; Shiono, M; Ohara, Y; Takatani, S; Noon, G P; Nosé, Y

    1993-01-01

    We are developing a new centrifugal pump, the Baylor Gyro Centrifugal Pump (Gyro Pump), which can function for more than 2 weeks. The concept of the Gyro Pump is that a one-piece rotor-impeller with embedded permanent magnets, driven directly by a brushless direct current motor stator placed outside, rotates like a "gyroscope," and the rotor-impeller is supported by one pivot bearing at the bottom in accordance with the gyroscopic principle. This concept enables us to eliminate a driving shaft and a seal between the driving shaft and the blood chamber, which results in extending the life of the centrifugal pump. The blood passes through the space between the motor stator and the rotor to the impeller portion. In this preliminary phase, two pivot bearings were applied to support the rotor-impeller at the top and the bottom inside the blood chamber. Both pivot bearings showed less blood trauma and less thrombogenicity in in vitro and in vivo studies. The Gyro Pump is a promising second-generation centrifugal pump for long-term circulatory support in the near future.

  4. Fluid dynamic noise in a centrifugal pump

    NASA Astrophysics Data System (ADS)

    Tse, D. G.; Whitelaw, J. H.

    1993-08-01

    Pressure distributions and frequency spectra have been obtained in a centrifugal pump having flow rates between the design point and near shut-down. The pump was comprised of a radial flow impeller with four backswept blades and a single volute. Measurements were obtained at the design flow rate and at off-design conditions to advance understanding of noise generation, to quantify the contribution of tonal, narrowband and broadband components to the overall noise and to develop strategies for suppressing fluid dynamic noise by flow control and active control. Fluid dynamic noise was generated by the unsteady conditions encountered by the impeller blade. Unsteady conditions originated from non-uniformities at the inlet and the impeller outlet at design and off-design conditions. Inlet flow non-uniformity was induced by separation regions. Flow separations are inherent in turbomachinery because of growth of the boundary layer and the disturbance effect of the rotating impeller. Flow non-uniformity at the impeller outlet stemmed from inlet flow non-uniformities in the inlet, from propagation of pressure waves in a vaneless diffuser, and from scroll effects.

  5. The design and application of a pediatric centrifugal pump.

    PubMed

    Ding, W X; Yu, X Q; Su, Z K; Huang, H M

    1997-12-01

    This centrifugal pump (CP) includes two parts: the blood pump and the driving apparatus. They are connected by six twin magnetic disc plates and driven by a magnetic DC motor (120W). The blood pump had six leaves deadlocked between two plastic discs. Six leaves were set at 30 degrees angles, separately. In the lower chamber of the CP, there was an inlay magnetic disc, which is connected with the disc leaves by an axis. This axis was sealed by silicon rubber and a ceramic ring. The priming volume of the blood chamber was 34 ml. In vitro testing showed that the free hemoglobin caused by the CP was much less than that caused by a roller pump after 180 min. The effect of this CP on blood cell damage was also studied in an animal model. Six goats were placed on cardiopulmonary bypass for 180 min. Perfusion flow rates were maintained between 1.5 and 2.5 L/min. The plasma free hemoglobin was lower in the CP group (6.04 mg/dL) than in the roller pump group (32.25 mg/dL), p < 0.01. The CP has been used in ten pediatric patients undergoing cardiopulmonary bypass surgery. The patients' ages were from three to five years, and body weights were from 15 to 20 kg. Perfusion flow rates were maintained between 1.8 and 2.5 L/min, and bypass times were from 30 to 50 min. The rotation speeds were from 2000 to 2500 rpm. All the patients recovered smoothly, and no hemoglobinuria occurred.

  6. Investigation of Flow in a Centrifugal Pump

    NASA Technical Reports Server (NTRS)

    Fischer, Karl

    1946-01-01

    The investigation of the flow in a centrifugal pump indicated that the flow patterns in frictional fluid are fundamentally different from those in frictionless fluid. In particular, the dead air space adhering to the section side undoubtedly causes a reduction of the theoretically possible delivery head. The velocity distribution over a parallel circle is also subjected to a noticeable change as a result of the incomplete filling of the passages. The relative velocity on the pressure side of the vane, which for passages completely filled with active flow would differ little from zero even at comparatively lower than normal delivery volume, is increased, so that no rapid reverse flow occurs on the pressure side of the vane even for smaller delivery volume. It was established, further, that the flow ceases to be stationary for very small quantities of water. The inflow to the impeller can be regarded as radial for the operating range an question. The velocity triangles at the exit are subjected to a significant alteration in shape ae a result of the increased peripheral velocity, which may be of particular importance in the determination of the guide vane entrance angle.

  7. Latex micro-balloon pumping in centrifugal microfluidic platforms.

    PubMed

    Aeinehvand, Mohammad Mahdi; Ibrahim, Fatimah; Harun, Sulaiman Wadi; Al-Faqheri, Wisam; Thio, Tzer Hwai Gilbert; Kazemzadeh, Amin; Madou, Marc

    2014-03-07

    Centrifugal microfluidic platforms have emerged as point-of-care diagnostic tools. However, the unidirectional nature of the centrifugal force limits the available space for multi-step processes on a single microfluidic disc. To overcome this limitation, a passive pneumatic pumping method actuated at high rotational speeds has been previously proposed to pump liquid against the centrifugal force. In this paper, a novel micro-balloon pumping method that relies on elastic energy stored in a latex membrane is introduced. It operates at low rotational speeds and pumps a larger volume of liquid towards the centre of the disc. Two different micro-balloon pumping mechanisms have been designed to study the pump performance at a range of rotational frequencies from 0 to 1500 rpm. The behaviour of the micro-balloon pump on the centrifugal microfluidic platforms has been theoretically analysed and compared with the experimental data. The experimental data show that the developed pumping method dramatically decreases the required rotational speed to pump liquid compared to the previously developed pneumatic pumping methods. It also shows that within a range of rotational speed, a desirable volume of liquid can be stored and pumped by adjusting the size of the micro-balloon.

  8. The CentriMag centrifugal blood pump as a benchmark for in vitro testing of hemocompatibility in implantable ventricular assist devices.

    PubMed

    Chan, Chris H H; Pieper, Ina Laura; Hambly, Rebecca; Radley, Gemma; Jones, Alyssa; Friedmann, Yasmin; Hawkins, Karl M; Westaby, Stephen; Foster, Graham; Thornton, Catherine A

    2015-02-01

    Implantable ventricular assist devices (VADs) have proven efficient in advanced heart failure patients as a bridge-to-transplant or destination therapy. However, VAD usage often leads to infection, bleeding, and thrombosis, side effects attributable to the damage to blood cells and plasma proteins. Measuring hemolysis alone does not provide sufficient information to understand total blood damage, and research exploring the impact of currently available pumps on a wider range of blood cell types and plasma proteins such as von Willebrand factor (vWF) is required to further our understanding of safer pump design. The extracorporeal CentriMag (Thoratec Corporation, Pleasanton, CA, USA) has a hemolysis profile within published standards of normalized index of hemolysis levels of less than 0.01 g/100 L at 100 mm Hg but the effect on leukocytes, vWF multimers, and platelets is unknown. Here, the CentriMag was tested using bovine blood (n = 15) under constant hemodynamic conditions in comparison with a static control for total blood cell counts, hemolysis, leukocyte death, vWF multimers, microparticles, platelet activation, and apoptosis. The CentriMag decreased the levels of healthy leukocytes (P < 0.006), induced leukocyte microparticles (P < 10(-5) ), and the level of high molecular weight of vWF multimers was significantly reduced in the CentriMag (P < 10(-5) ) all compared with the static treatment after 6 h in vitro testing. Despite the leukocyte damage, microparticle formation, and cleavage of vWF multimers, these results show that the CentriMag is a hemocompatible pump which could be used as a standard in blood damage assays to inform the design of new implantable blood pumps.

  9. Rotary blood pump

    NASA Technical Reports Server (NTRS)

    Bozeman, Richard J. (Inventor); Akkerman, James W. (Inventor); Aber, Greg S. (Inventor); Vandamm, George A. (Inventor); Bacak, James W. (Inventor); Svejkovsky, Paul A. (Inventor); Benkowski, Robert J. (Inventor)

    1993-01-01

    A rotary blood pump is presented. The pump includes a pump housing for receiving a flow straightener, a rotor mounted on rotor bearings and having an inducer portion and an impeller portion, and a diffuser. The entrance angle, outlet angle, axial, and radial clearances of the blades associated with the flow straightener, inducer portion, impeller portion, and diffuser are optimized to minimize hemolysis while maintaining pump efficiency. The rotor bearing includes a bearing chamber that is filled with crosslinked blood or other bio-compatible material. A back emf integrated circuit regulates rotor operation and a microcomputer may be used to control one or more back emf integrated circuits. A plurality of magnets are disposed in each of a plurality of impeller blades with a small air gap. A stator may be axially adjusted on the pump housing to absorb bearing load and maximize pump efficiency.

  10. 2. View of centrifugal pump house sitting at edge of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. View of centrifugal pump house sitting at edge of drainage canal, looking E. - Laurel Valley Sugar Plantation, Drainage Plant, 2 Miles South of Thibodaux on State Route 308, Thibodaux, Lafourche Parish, LA

  11. Development of an atraumatic small centrifugal pump for second-generation cardiopulmonary bypass.

    PubMed

    Jikuya, T; Sasaki, T; Aizawa, T; Shiono, M; Glueck, J A; Smith, C P; Feldman, L; Sakuma, I; Sekela, M E; Noda, T

    1992-12-01

    A small and light direct-drive centrifugal pump has been developed for cardiopulmonary bypass. In the development process, blood compatibility studies including a hemolysis study, an in vitro fluid dynamic performance study, and in vivo durability and feasibility studies were performed. The centrifugal pump with a 50 mm diameter impeller resulted in almost the same index of hemolysis value as did a Bio-Medicus centrifugal pump. Heat dissipation from the motor was prevented by using a flexible drive cable. Forty-eight-hour sealing durability around the driving axis was accomplished by using a fluoro-rubber V-ring that connected to the hard chrome-plated stainless steel. In vitro and in vivo performances of the pump were satisfactory. Thrombus formation behind the impeller was prevented by using a holed impeller that generated blood flow from the back to the surface of the impeller. Elimination of air during priming procedures was also easier with this modification. This centrifugal pump has one-quarter of the priming volume, size, and weight of magnetically coupled centrifugal pump systems.

  12. Rotary Blood Pump

    NASA Technical Reports Server (NTRS)

    Bozeman, Richard J., Jr. (Inventor); Akkerman, James W. (Inventor); Aber, Gregory S. (Inventor); VanDamm, George A. (Inventor); Bacak, James W. (Inventor); Svejkovsky, Paul A. (Inventor); Benkowski, Robert J. (Inventor)

    1996-01-01

    A rotary blood pump includes a pump housing for receiving a flow straightener, a rotor mounted on rotor bearings and having an inducer portion and an impeller portion, and a diffuser. The entrance angle, outlet angle, axial and radial clearances of blades associated with the flow straightener, inducer portion, impeller portion and diffuser are optimized to minimize hemolysis while maintaining pump efficiency. The rotor bearing includes a bearing chamber that is filled with cross-linked blood or other bio-compatible material. A back emf integrated circuit regulates rotor operation and a microcomputer may be used to control one or more back emf integrated circuits. A plurality of magnets are disposed in each of a plurality of impeller blades with a small air gap. A stator may be axially adjusted on the pump housing to absorb bearing load and maximize pump efficiency.

  13. Rotary blood pump

    NASA Technical Reports Server (NTRS)

    Benkowski, Robert J. (Inventor); Kiris, Cetin (Inventor); Kwak, Dochan (Inventor); Rosenbaum, Bernard J. (Inventor); Bacak, James W. (Inventor); DeBakey, Michael E. (Inventor)

    1999-01-01

    A blood pump that comprises a pump housing having a blood flow path therethrough, a blood inlet, and a blood outlet; a stator mounted to the pump housing, the stator having a stator field winding for producing a stator magnetic field; a flow straightener located within the pump housing, and comprising a flow straightener hub and at least one flow straightener blade attached to the flow straightener hub; a rotor mounted within the pump housing for rotation in response to the stator magnetic field, the rotor comprising an inducer and an impeller; the inducer being located downstream of the flow straightener, and comprising an inducer hub and at least one inducer blade attached to the inducer hub; the impeller being located downstream of the inducer, and comprising an impeller hub and at least one impeller blade attached to the impeller hub; and preferably also comprising a diffuser downstream of the impeller, the diffuser comprising a diffuser hub and at least one diffuser blade. Blood flow stagnation and clot formation within the pump are minimized by, among other things, providing the inducer hub with a diameter greater than the diameter of the flow straightener hub; by optimizing the axial spacing between the flow straightener hub and the inducer hub, and between the impeller hub and the diffuser hub; by optimizing the inlet angle of the diffuser blades; and by providing fillets or curved transitions between the upstream end of the inducer hub and the shaft mounted therein, and between the impeller hub and the shaft mounted therein.

  14. Design of a Bearingless Blood Pump

    NASA Technical Reports Server (NTRS)

    Barletta, Natale; Schoeb, Reto

    1996-01-01

    In the field of open heart surgery, centrifugal blood pumps have major advantages over roller pumps. The main drawbacks to centrifugal pumps are however problems with the bearings and with the sealing of the rotor shaft. In this paper we present a concept for a simple, compact and cost effective solution for a blood pump with a totally magnetically suspended impeller. It is based on the new technology of the 'Bearingless Motor' and is therefore called the 'Bearingless Blood Pump.' A single bearingless slice motor is at the same time a motor and a bearing system and is able to stabilize the six degrees of freedom of the pump impeller in a very simple way. Three degrees of freedom are stabilized actively (the rotation and the radial displacement of the motor slice). The axial and the angular displacement are stabilized passively. The pump itself (without the motor-stator and the control electronics) is built very simply. It consists of two parts only: the impeller with the integrated machine rotor and the housing. So the part which gets in contact with blood and has therefore to be disposable, is cheap. Fabricated in quantities, it will cost less than $10 and will therefore be affordable for the use in a heart-lung-machine.

  15. Operation effectiveness of wells by enhancing the electric- centrifugal pump

    NASA Astrophysics Data System (ADS)

    Zyatikov, P. N.; Kozyrev, I. N.; Deeva, V. S.

    2016-09-01

    We present the method to improve the operation effectiveness of wells by enhancing the electric-centrifugal pump. Some of the best ways to extend the electric-centrifugal pumps operating lifetime is using today's techniques as well as additional protective equipment as a part of the electric-centrifugal pump. In paper it is shown that high corrosiveness of formation fluid (a multi-component medium composed of oil, produced water, free and dissolved gases) is a major cause of failures of downhole equipment. Coil tubing is the most efficient technology to deal with this problem. The experience of coil tubing operations has proved that high-quality bottom hole cleaning saving the cost of operation due to a decreased failure rate of pumps associated with ejection of mechanical impurity.

  16. Neutrophil adhesion molecule expression during cardiopulmonary bypass: a comparative study of roller and centrifugal pumps.

    PubMed

    Macey, M G; McCarthy, D A; Trivedi, U R; Venn, G E; Chambers, D J; Brown, K A

    1997-09-01

    The purpose of this study was to determine whether adhesion molecules and markers of cell activation were preferentially increased on blood neutrophils during cardiopulmonary bypass (CPB) and whether such effects were influenced by the use of a roller pump or a centrifugal pump. Forty-six patients undergoing open heart surgery were randomly allocated into either the roller or centrifugal groups. Blood (1 ml volumes) was removed from arterial and venous lines immediately before and 1 h after the start of bypass. Whole blood samples were immunolabelled and flow cytometry used to measure the distribution and expression of the adhesion molecules CD11b, CD18, CD62L on neutrophils, monocytes and lymphocytes, in addition to CD64 on neutrophils and monocytes, and CD14 on monocytes. The expression of CD11b was significantly enhanced on neutrophils in arterial and venous samples from both the roller pump (mean 84% and 100% increase, respectively; p < 0.001) and centrifugal pump (mean 74% and 73% increase, respectively; p < 0.001) groups. Neutrophil L-selectin expression increased to a small but significant extent in arterial and venous samples from the centrifugal pump group (mean 16% increase; p < 0.001) and in venous samples from the roller pump group (mean 10% increase; p < 0.01). Neither the percentage of neutrophils bearing CD11b/CD18, CD62L and CD64, nor the expression of adhesion molecules on lymphocytes and monocytes were modified by 1 h of bypass. These results suggest that patients subjected to CPB with roller or centrifugal pumps are equally at risk to neutrophil activation that could lead to increased interaction of these cells with blood vessel walls.

  17. Evaluation of HL-20 roller pump and Rotaflow centrifugal pump on perfusion quality and gaseous microemboli delivery.

    PubMed

    Yee, Stella; Qiu, Feng; Su, Xiaowei; Rider, Alan; Kunselman, Allen R; Guan, Yulong; Undar, Akif

    2010-11-01

    The purpose of this study was to compare the HL-20 roller pump (Jostra USA, Austin, TX, USA) and Rotaflow centrifugal pump (Jostra USA) on hemodynamic energy production and gaseous microemboli (GME) delivery in a simulated neonatal cardiopulmonary bypass (CPB) circuit under nonpulsatile perfusion. This study employed a simulated model of the pediatric CPB including a Jostra HL-20 heart-lung machine (or a Rotaflow centrifugal pump), a Capiox BabyRX05 oxygenator (Terumo Corporation, Tokyo, Japan), a Capiox pediatric arterial filter (Terumo Corporation), and ¼-inch tubing. The total volume of the experimental system was 700mL (500mL for the circuit and 200mL for the pseudo neonatal patient). The hematocrit was maintained at 30% using human blood. At the beginning of each trial, a 5mL bolus of air was injected into the venous line. Both GME data and pressure values were recorded at postpump and postoxygenator sites. All the experiments were conducted under nonpulsatile perfusion at three flow rates (500, 750, and 1000mL/min) and three blood temperatures (35, 30, and 25°C). As n=6 for each setup, a total of 108 trials were done. The total number of GME increased as temperature decreased from 35°C to 25°C in the trials using the HL-20 roller pump while the opposite effect occurred when using the Rotaflow centrifugal pump. At a given temperature, total GME counts increased with increasing flow rates for both pumps. Results indicated the Rotaflow centrifugal pump delivered significantly fewer microemboli compared to the HL-20 roller pump, especially under high flow rates. Less than 10% of total microemboli were larger than 40µm in size and the majority of GME were in the 0-20µm class in all trials. Postpump total hemodynamic energy (THE) increased with increasing flow rates and decreasing temperatures in both circuits using these two pumps. The HL-20 roller pump delivered more THE than the Rotaflow centrifugal pump at all tested flow rates and temperature conditions

  18. [Temporary use of centrifugal pump for pump thrombosis in patients with paracorporeal ventricular assist device].

    PubMed

    Kimura, Mitsutoshi; Kinoshita, Osamu; Nawata, Kan; Yamauchi, Haruo; Itoda, Yoshifumi; Hoshino, Yasuhiro; Kashiwa, Koichi; Kubo, Hitoshi; Kurosawa, Hideo; Takahashi, Mai; Koga, Sayaka; Ono, Minoru

    2015-05-01

    Nipro paracorporeal ventricular assist device( VAD) is often associated with pump thrombosis which causes severe complications such as brain infarction, often requiring pump change. However, Nipro VAD pump is an expensive device and it is difficult to change pumps frequently at a short interval. We have temporarily used Rotaflow centrifugal pump for recurrent pump thrombosis in patients with Nipro VADs. From January 2012 through December 2013, 19 patients underwent Nipro VADs implantation at our institution, and 9 of them underwent pump change from Nipro pumps to Rotaflow centrifugal pumps. A total of 25 Rotaflow centrifugal pumps were used in these 9 patients, with the total circulatory support duration of 526 days. The median support period was 15 days (range;2-128 days). There were 2 cerebrovascular accidents and 1 Rotaflow pump circuit thrombosis during this period. Change from Rotaflow to Nipro VAD pump resulted in decrease in hematocrit by about 3 point. There was no difference in liver or renal function between before and after the pump change. Our results suggest that temporary use of Rotaflow centrifugal pump for recurrent pump thrombosis in patients with Nipro VADs may be a promising alternative.

  19. Small centrifugal pumps for low thrust rockets

    NASA Technical Reports Server (NTRS)

    Gulbrandsen, N. C.; Furst, R. B.; Burgess, R. M.; Scheer, D. D.

    1985-01-01

    This paper presents the results of a combined analytical and experimental investigation of low specific speed pumps for potential use as components of propellant feed systems for low thrust rocket engines. Shrouded impellers and open face impellers were tested in volute type and vaned diffuser type pumps. Full- and partial-emission diffusers and full- and partial-admission impellers were tested. Axial and radial loads, head and efficiency versus flow, and cavitation tests were conducted. Predicted performance of two pumps are compared when pumping water and liquid hydrogen. Detailed pressure loss and parasitic power values are presented for two pump configurations. Partial-emission diffusers were found to permit use of larger impeller and diffuser passages with a minimal performance penalty. Normal manufacturing tolerances were found to result in substantial power requirement variation with only a small pressure rise change. Impeller wear ring leakage was found to reduce pump pressure rise to an increasing degree as the pump flowrate was decreased.

  20. The effect of gas fraction on centrifugal pump

    NASA Astrophysics Data System (ADS)

    Zhu, Z. T.; Wang, Y.; Zhao, L. F.; Ning, C.; Xie, S. F.; Liu, Z. C.

    2015-01-01

    In order to study the multiphase flow field in M125 centrifugal pump, three-dimensional modeling was used for internal flow through three-dimensional software Pro/E. Then based on SST turbulence model combining with Rayleigh-Plesset cavitation model, and structured grid to simulate the hydraulic characteristics of volute and impeller within different gas conditions. The velocity, pressure and gas volume fraction distributions of the interior flow field of volute and impeller were obtained and analyzed, which revealed the effect of gas fractions on the flow characteristic of the centrifugal pump.

  1. A new control method that estimates the backflow in a centrifugal pump.

    PubMed

    Nakata, K; Ohtsuka, G; Yoshikawa, M; Takano, T; Glueck, J; Fujisawa, A; Makinouchi, K; Yokokawa, M; Nosé, Y

    1999-06-01

    The rotary blood pump will be widely used in the near future as an implantable left ventricular assist device (LVAD). However, one obstacle for the centrifugal pump is a control method that can maintain an optimum flow rate in a physiological condition. Thus, the object of this study is to develop this optimum control system for the centrifugal pump. If the heart function and pump efficiency are stable, the ratio of the systole current to the the diastole current (S/D) will be a fixed value. However, if the heart function and pump efficiency are unstable, S/D will not be a fixed value. This control system was investigated with a calf that was subjected to an ex vivo LVAD study. The LVAD was a Gyro C1E3 centrifugal pump. The pump flow rate was changed to 1.5, 3.5, 5.2, and 6.2 L/min. According to the changes of the pump flow rates, the S/D values were 1.01 +/- 0.01, 1.06 +/- 0.05, 1.03 +/- 0.01, and 1.03 +/- 0.01, respectively. There was no statistical difference among the 3 groups. In a separate experiment, the backflow condition S/D was 1.88 +/- 0.6, and the normal condition S/D was 1.35 +/- 0.5. There was a statistical difference between the 2 groups. The results of this study suggest that S/D is not influenced by the pump flow rate. However, the S/D was changed when the pump was in a backflow condition. This method will be useful in controlling a centrifugal pump requiring only electrical current information.

  2. Axial and centrifugal pump meanline performance analysis

    NASA Technical Reports Server (NTRS)

    Veres, Joseph P.

    1994-01-01

    A meanline pump flow modeling method has been developed to provide a fast capability for modeling pumps of cryogenic rocket engines. Based on this method, a meanline pump flow code (PUMPA) has been written that can predict the performance of pumps at off-design operating conditions, given the loss of the diffusion system at the design point. The design point rotor efficiency is obtained from empirically derived correlations of loss to rotor specific speed. The rapid input setup and computer run time for the meanline pump flow code makes it an effective analysis and conceptual design tool. The map generation capabilities of the PUMPA code provide the information needed for interfacing with a rocket engine system modeling code.

  3. Characterization of a centrifugal pump in He II

    NASA Technical Reports Server (NTRS)

    Weisend, J. G., II; Van Sciver, S. W.

    1988-01-01

    As part of an effort to determine the feasibility of helium transfer in space, a centrifugal pump was tested in He II at a variety of flow rates, pump speeds, and fluid temperatures. The pump, which has a straight bladed impeller 6.86 cm in diameter, generated a maximum pressure rise of 15 kPa and a maximum flow rate of 22 g/s for the conditions of the test. Pump performance seems to be independent of fluid temperature and is in good agreement with the values predicted by the manufacturer. Over the range of flow coefficients, the measured maximum efficiency is around 50 percent. Cavitation is observed in the pump and is thought to be highly dependent on the local heating of the helium in the pump. Preliminary measurements of the noise spectra of the pump suggest a possible mechanism to predict the onset of cavitation.

  4. Steam driven centrifugal pump for low cost boiler feed service

    SciTech Connect

    Not Available

    1982-11-01

    This article describes a steam driven centrifugal pump for boiler feed-water and other high pressure water applications, which was awarded Top Honors in the special pumps category of the 1982 Chemical processing Vaaler competition, because the simple design with turbine, pump and controls combined in an integral unit provides high operating efficiency and reliable performance with minimal maintenance. Single source responsibility for all components when the pump may have to be serviced is another advantage. These features meet the requirements for boiler feed pumps that are critical to maintaining a consistent steam supply in a process plant where downtime can be extremely expensive. The annual cost to operate the pump for 8000 hours is about $100,000, if electricity costs 5 cents/kwh. These pumps can be run for about $30,000 on steam, if natural gas costs $4.00/mcf. Cost savings are $70,000 annually.

  5. Clinical experience with Nikkiso centrifugal pumps for extracorporeal circulation.

    PubMed

    Onoda, K; Kondo, C; Mizumoto, T; Kusagawa, H; Katayama, Y; Hayashi, T; Komada, T; Hirano, R; Miyamura, T; Tanaka, J

    1994-09-01

    A comparative study of a newly developed impeller-type centrifugal pump, Nikkiso HMS-15, was made to assess the effects on hemolysis, platelet function, and renal function for extracorporeal circulation (ECC) during open heart surgery. The Bio-pump (cone-type, Medtronic) and the roller pump were used as controls. The increase of serum hemoglobin level in the Nikkiso pump was significantly lower than that in the other pumps. The decrease of platelet counts was recognized after the initiation of ECC in the three pumps whereas the levels of platelet factor 4 and beta-thromboglobulin in the Nikkiso pump group increased by far less than in the other two groups. Moreover, renal function was better maintained in the Nikkiso pump group; in particular, a significantly higher urine output was recorded during ECC and for 1 h after the termination of ECC. The results of our clinical studies suggest that the Nikkiso centrifugal pump is suitable for ECC during open heart surgery.

  6. Use minimum flow data to prolong centrifugal pump life

    SciTech Connect

    Reynolds, J.A.

    1996-03-01

    Environmental and safety concerns and, in the US, the consequences of failing of meet EPA regulations are intensifying efforts to improve the reliability of pumping equipment. A critical step toward achieving this goal is eliminating cavitation, and the resulting impeller and shaft vibrations, which, ultimately, cause seal and bearing failure. In centrifugal pumps, cavitation results when they run at very low flow rates, as can happen during unplanned upsets or interruptions. This particularly true since many centrifugal pumps are now controlled by automatic valves in their discharge lines. The problem can be prevented by providing a small bypass line to the pump`s suction source, to control temperature rise in the pump. Usually, the minimum flow is so low that the bypass loop can be kept open without detracting from the pump`s efficiency. It needn`t require a flow control valve or any special instrumentation, but will let the pump run at a comfortable flow, even with the control valve closed. This paper describes a method to determine minimum thermal flow to prevent cavitation.

  7. Blood Pump Bearing System

    NASA Technical Reports Server (NTRS)

    Aber, Gregory S. (Inventor)

    2000-01-01

    An apparatus is provided for a blood pump bearing system within a pump housing to support long-term highspeed rotation of a rotor with an impeller blade having a plurality of individual magnets disposed thereon to provide a small radial air gap between the magnets and a stator of less than 0.025 inches. The bearing system may be mounted within a flow straightener, diffuser, or other pump element to support the shaft of a pump rotor. The bearing system includes a zirconia shaft having a radiused end. The radiused end has a first radius selected to be about three times greater than the radius of the zirconia shaft. The radiused end of the zirconia shaft engages a flat sapphire endstone. Due to the relative hardness of these materials a flat is quickly produced during break-in on the zirconia radiused end of precisely the size necessary to support thrust loads whereupon wear substantially ceases. Due to the selection of the first radius, the change in shaft end-play during pump break-in is limited to a total desired end-play of less than about 0.010 inches. Radial loads are supported by an olive hole ring jewel that makes near line contact around the circumference of the Ir shaft to support big speed rotation with little friction. The width of olive hole ring jewel is small to allow heat to conduct through to thereby prevent heat build-up in the bearing. A void defined by the bearing elements may fill with blood that then coagulates within the void. The coagulated blood is then conformed to the shape of the bearing surfaces.

  8. Blood Pump Bearing System

    NASA Technical Reports Server (NTRS)

    Aber, Gregory S. (Inventor)

    1999-01-01

    Methods and apparatus are provided for a blood pump bearing system within a pump housing to support long-term high-speed rotation of a rotor with an impeller blade having a plurality of individual magnets disposed thereon to provide a small radial air gap between the magnets and a stator of less than 0.025 inches. The bearing system may be mounted within a flow straightener, diffuser, or other pump element to support the shaft of a pump rotor. The bearing system includes a zirconia shaft having a radiused end. The radiused end has a first radius selected to be about three times greater than the radius of the zirconia shaft. The radiused end of the zirconia shaft engages a flat sapphire endstone. Due to the relative hardness of these materials a flat is quickly produced during break-in on the zirconia radiused end of precisely the size necessary to support thrust loads whereupon wear substantially ceases. Due to the selection of the first radius, the change in shaft end-play during pump break-in is limited to a total desired end-play of less than about 0.010 inches. Radial loads are supported by an olive hole ring jewel that makes near line contact around the circumference of the shaft to support high speed rotation with little friction. The width of olive hole ring jewel is small to allow heat to conduct through to thereby prevent heat build-up in the bearing. A void defined by the bearing elements may fill with blood that then coagulates within the void. The coagulated blood is then conformed to the shape of the bearing surfaces.

  9. Whole blood pumping with a microthrottle pump

    PubMed Central

    Davies, M. J.; Johnston, I. D.; Tan, C. K. L.; Tracey, M. C.

    2010-01-01

    We have previously reported that microthrottle pumps (MTPs) display the capacity to pump solid phase suspensions such as polystyrene beads which prove challenging to most microfluidic pumps. In this paper we report employing a linear microthrottle pump (LMTP) to pump whole, undiluted, anticoagulated, human venous blood at 200 μl min−1 with minimal erythrocyte lysis and no observed pump blockage. LMTPs are particularly well suited to particle suspension transport by virtue of their relatively unimpeded internal flow-path. Micropumping of whole blood represents a rigorous real-world test of cell suspension transport given blood’s high cell content by volume and erythrocytes’ relative fragility. A modification of the standard Drabkin method and its validation to spectrophotometrically quantify low levels of erythrocyte lysis by hemoglobin release is also reported. Erythrocyte lysis rates resulting from transport via LMTP are determined to be below one cell in 500 at a pumping rate of 102 μl min−1. PMID:21264059

  10. Measurements of the rotordynamic shroud forces for centrifugal pumps

    NASA Technical Reports Server (NTRS)

    Guinzburg, A.; Brennen, C. E.; Acosta, A. J.; Caughey, T. K.

    1990-01-01

    An experiment was designed to measure the rotordynamic shroud forces on a centrifugal pump impeller. The measurements were done for various whirl/impeller speed ratios and for different flow rates. A destabilizing tangential force was measured for small positive whirl ratios and this force decreased with increasing flow rate.

  11. In vitro evaluation of the TandemHeart pediatric centrifugal pump.

    PubMed

    Svitek, Robert G; Smith, Douglas E; Magovern, James A

    2007-01-01

    The pediatric TandemHeart pump is being developed for short-term circulatory support of patients varying in size from 2 to 40 kg. The pump withdraws blood from the left atrium via cannula inserted percutaneously, either through the right internal jugular vein or transhepatically, and pumps the blood back into the arterial system via the carotid or femoral artery. High resolution stereolithography (SLA) was used to create an upper housing and impeller design, which were assembled into a functional pump prototype. Pressure-flow characteristics of the pump were determined in a blood analogue solution and compared with the pressure-flow requirements of the intended cannulation. At 5,500 rpm, the pump was able to generate 0.4 L/min of flow with a pressure rise of 325 mm Hg and 2.0 L/min with a pressure rise of 250 mm Hg. The hydraulic performance of the pump will enable at least 50% of cardiac output when the arterial cannula is placed in the carotid artery. The hemolysis of the TandemHeart pediatric pump at 5,500 rpm was compared with the BP-50 pediatric centrifugal pump in vitro using bovine blood flowing at 0.4 L/min against 250 mm Hg. The TandemHeart pump produced a similar increase in plasma free hemoglobin levels during the duration of the 6 hour test.

  12. 77 FR 65360 - Grant of Authority for Subzone Status (Centrifugal and Submersible Pumps); Auburn, NY

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-26

    ... Foreign-Trade Zones Board Grant of Authority for Subzone Status (Centrifugal and Submersible Pumps... subzone at the centrifugal and submersible pump manufacturing and warehousing facilities of Xylem Water... activity related to the manufacturing of centrifugal and submersible pumps and related controllers at...

  13. Optimization of centrifugal pump cavitation performance based on CFD

    NASA Astrophysics Data System (ADS)

    Xie, S. F.; Wang, Y.; Liu, Z. C.; Zhu, Z. T.; Ning, C.; Zhao, L. F.

    2015-01-01

    In order to further improve the cavitation performance of a centrifugal pump, slots on impeller blade near inlet were studied and six groups of hydraulic model were designed. Base on cavitating flow feature inside a centrifugal pump, bubble growth and implosion are calculated from the Rayleigh-Plesset equation which describes the dynamic behavior of spherical bubble and RNG κ-epsilon model was employed to simulate and analyze the internal two-phase flow of the model pump under the same conditions. The simulation results show that slots on blade near inlet could improve the cavitation performance and cavitation performance improvement of the second group was more obvious. Under the same conditions, the pressure on the back of blade near inlet was higher than the pressure on the back of unmodified blade near inlet, and energy distribution in the flow channel between the two blades was more uniform with a small change of head.

  14. Biventricular support using a centrifugal pump in a 6 year old with fulminant myocarditis.

    PubMed

    Kehara, Hiromu; Takano, Tamaki; Terasaki, Takamitsu; Okada, Kenji

    2016-12-01

    We experienced a case of ventricular assist with both a pulsatile-flow and a continuous-flow pump in a pediatric patient, and herein report the clinical course and characteristics of the pumps. A 6-year-old female was diagnosed with fulminant myocarditis and transferred to our hospital for mechanical support. After 12 days of extracorporeal membrane oxygenation, we implanted a left ventricular assist device (LVAD) and a right ventricular assist device (RVAD) using centrifugal Gyro pumps with a membrane oxygenator in a paracorporeal fashion. The membrane oxygenator was removed on postoperative day (POD) 4, and the patient was weaned from the respirator on POD 6. The LVAD was exchanged on POD 13 and 17, and the RVAD was exchanged on POD 14 because of thrombus formation inside the pumps. The RVAD was removed on POD 25. On POD 32, the patient experienced cerebral infarction and the centrifugal Gyro pump was switched to an extracorporeal pulsatile pump. No thromboembolic event occurred after pump conversion, although continuous administration of vasodilators was required to avoid hypertension. She underwent successfully heart transplantation in the USA after 8 months of ventricular support. A centrifugal pump is considered useful for pediatric patients, as pump flow and blood pressure can be relatively easily controlled in the postoperative acute phase compared with the pulsatile pump. However, special care should be taken to monitor for thrombus formation when support length becomes longer than 13 days, and a switch to a pulsatile pump should be considered once the hemodynamic status stabilizes.

  15. Performance in He II of a centrifugal pump with a jet pump inducer

    NASA Astrophysics Data System (ADS)

    Daney, D. E.; Ludtke, P. R.; Kashani, A.

    1989-05-01

    The tendency of turbopumps operating in He II to cavitate makes their use in zero gravity questionable because of the zero net positive suction head (NPSH) available at the pump inlet. This paper investigates a jet pump, positioned at the inlet of a centrifugal pump with a screw inducer, as a means of operating a centrifugal pump at zero or lower NPSH. Pump performance in He II was measured as a function of NPSH for six different combinations of primary and secondary nozzles. Suction heads down to -91 mm were measured for a 3-percent reduction in developed head. These are referenced to the leading edge of the screw inducer, which is 100 mm above the jet pump inlet. Because cavitation at the primary jet always precedes cavitation in the jet pump secondary nozzle, the reverse (pressure driven) flow through a porous plug as a means of obtaining a subcooled primary jet was also tested. These tests were inconclusive.

  16. Advantages of temporary venoatrial shunt using centrifugal pump during bidirectional cavopulmonary shunt.

    PubMed

    Kotani, Yasuhiro; Honjo, Osami; Ishino, Kozo; Osaki, Satoru; Kuroko, Yosuke; Kawabata, Takuya; Ugaki, Shinya; Yoshizumi, Ko; Kasahara, Shingo; Kawada, Masaaki; Sano, Shunji

    2006-01-01

    Single-ventricle palliation without the use of cardiopulmonary bypass carries advantages that reduce systemic edema and inflammatory responses; however, simple clamping of the superior vena cava (SVC) without a temporary shunt leads to increase in cerebral venous pressure and subsequent decrease in cerebral blood flow during bidirectional cavopulmonary shunt (BCPS). We report our experience of BCPS, using a centrifugal pump-assisted temporary shunt. The criteria included an unrestrictive interatrial communication, the absence of atrioventricular valve regurgitation, and the existence of an antegrade pulmonary blood flow. From August 2000, 14 children with single-ventricle physiology met the criteria. The mean age was 1.0 +/- 0.9 years, and the mean weight was 8.4 +/- 2.6 kg. A temporary shunt was established between the SVC and the right atrium with right-angle cannulae, which were connected to a centrifugal pump to accelerate the blood flow from the SVC to the right atrium. All patients tolerated the procedure. Mean central venous pressure was 17 +/- 4 mm Hg, and transcutaneous oxygen saturation was maintained at 77 +/- 8% during anastomosis. No patients required blood transfusion. There were no postoperative neurological complications. The centrifugal pump-assisted temporary shunt offered safer and more effective circulatory support than other shunt systems, with excellent venous drainage in pediatric patients undergoing BCPS.

  17. Gyro-effect stabilizes unstable permanent maglev centrifugal pump.

    PubMed

    Qian, Kun-Xi

    2007-03-01

    According to Earnshaw's Theorem (1839), the passive maglev cannot achieve stable equilibrium and thus an extra coil is needed to make the rotor electrically levitated in a heart pump. The author had developed a permanent maglev centrifugal pump utilizing only passive magnetic bearings, to keep the advantages but to avoid the disadvantages of the electric maglev pumps. The equilibrium stability was achieved by use of so-called "gyro-effect": a rotating body with certain high speed can maintain its rotation stably. This pump consisted of a rotor (driven magnets and an impeller), and a stator with motor coil and pump housing. Two passive magnetic bearings between rotor and stator were devised to counteract the attractive force between the motor coil iron core and the rotor driven magnets. Bench testing with saline demonstrated a levitated rotor under preconditions of higher than 3,250 rpm rotation and more than 1 l/min pumping flow. Rotor levitation was demonstrated by 4 Hall sensors on the stator, with evidence of reduced maximal eccentric distance from 0.15 mm to 0.07 mm. The maximal rotor vibration amplitude was 0.06 mm in a gap of 0.15 mm between rotor and stator. It concluded that Gyro-effect can help passive maglev bearings to achieve stabilization of permanent maglev pump; and that high flow rate indicates good hydraulic property of the pump, which helps also the stability of passive maglev pump.

  18. Evaluation of floating impeller phenomena in a Gyro centrifugal pump.

    PubMed

    Nishimura, Ikuya; Ichikawa, S; Mikami, M; Ishitoya, H; Motomura, T; Kawamura, M; Linneweber, J; Glueck, J; Shinohara, T; Nosé, Y

    2013-01-01

    The Gyro centrifugal pump developed as a totally implantable artificial heart was designed with a free impeller, in which the rotational shaft (male bearing) of the impeller was completely separated from the female bearing. For this type of pump, it is very important to keep the proper magnet balance (impeller-magnet and actuator-magnet) in order to prevent thrombus formation and/or bearing wear. When the magnet balance is not proper, the impeller is jerked down into the bottom bearing. On the other hand, if magnet balance is proper, the impeller lifted off the bottom of the pump housing within a certain range of pumping conditions. In this study, this floating phenomenon was investigated in detail. The floating phenomenon was proved by observation of the impeller behavior using a transparent acrylic pump. The impeller floating phenomenon was mapped on a pump performance curve. The impeller floating phenomenon is affected by the magnet-magnet coupling distance and rotational speed of the impeller. In order to keep the proper magnet balance and to maintain the impeller floating phenomenon at the driving condition of right and left pump, the magnet-magnet coupling distance was altered by a spacer which was installed between the pump and actuator. It became clear that the same pump could handle different conditions (right and left ventricular assist), by just changing the thickness of the spacer. When magnet balance is proper, the floating impeller phenomenon occurs automatically in response to the impeller rev. It is called "the dynamic RPM suspension".

  19. Rotating and positive-displacement pumps for low-thrust rocket engines. Volume 1: Pump Evaluation and design. [of centrifugal pumps

    NASA Technical Reports Server (NTRS)

    Macgregor, C.; Csomor, A.

    1974-01-01

    Rotating and positive displacement pumps of various types were studied for pumping liquid fluorine for low-thrust, high-performance rocket engines. Included in the analysis were: centrifugal, pitot, Barske, Tesla, drag, gear, vane, axial piston, radial piston, diaphragm, and helirotor pump concepts. The centrifugal pump and the gear pump were selected and these were carried through detailed design and fabrication. Mechanical difficulties were encountered with the gear pump during the preliminary tests in Freon-12. Further testing and development was therefore limited to the centrifugal pump. Tests on the centrifugal pump were conducted in Freon-12 to determine the hydrodynamic performance and in liquid fluorine to demonstrate chemical compatibility.

  20. Analysis of the reliability of submersible centrifugal electric pumping systems

    SciTech Connect

    Shilyaev, V.A.; Solodovnikov, G.G.; Vikhman, R.G.; Koshelev, V.A.; Zhitina, G.S.; Chirkova, N.I.

    1987-01-01

    A modern submersible centrifugal electric pumping system (SCEPS) for oil production consists of a submersible part which includes a centrifugal pump, an electric motor, a hydroprotection arrangement, a cable line, and an aboveground part that includes a control station and a transformer. The author discusses the mean service life of the submersible part of the SCEPS as the most important parameter of reliability of the SCEPS. The effect of the operating factors is assessed by calculating the mean service life of the submersible part of the typical SCEPS, making allowance for failures resulting from all causes. The mean operating time until failure of the submersible part of the new SCEPS due to design and technological error was determined.

  1. The spindle pump. Development of a nonpulsatile blood pump for assisted circulation.

    PubMed

    Hager, J; Brandstaetter, F; Koller, I; Unger, F

    1989-01-01

    The spindle pump is a combined working nonpulsatile blood pump, i.e., a centrifugally propelling device. This special concept was chosen to tackle the main problems of nonpulsatile pumps, such as thromboembolic complications, sealing difficulties, and traumatic hemolysis. The first two of these problems were relatively simple to solve compared with the third problem--traumatic hemolysis. Various modifications and constructive steps of the spindle pump were necessary to keep stress on blood components within adequate limits. The actual prototype--tested in three acute experiments and eight experiments with a longer pumping duration (the longest lasting 63 hours)--is described in extenso, and its development is discussed.

  2. MedTech Mag-Lev, single-use, extracorporeal magnetically levitated centrifugal blood pump for mid-term circulatory support.

    PubMed

    Nagaoka, Eiki; Fujiwara, Tatsuki; Kitao, Takashi; Sakota, Daisuke; Shinshi, Tadahiko; Arai, Hirokuni; Takatani, Setsuo

    2013-01-01

    Short- to mid-term extracorporeal ventricular assist devices (VADs) are recommended for critical cardiogenic shock patients. We have designed a preclinical, single-use MedTech Mag-Lev VAD for one-month extracorporeal use. The impeller-rotor of the pump was suspended by a two degree-of-freedom active magnetic bearing in a 300 μm fluid gap, where the computational fluid dynamics analysis predicted a secondary flow of about 400-500 ml/min at a pump speed of 1800-2200 rpm. Three eddy current sensors were employed to implement noise- and drift-free magnetic levitation. The pump components were injection molded using polycarbonate for smooth surfaces as well as improved reproducibility, followed by coating with a biocompatible 2-methacryloyl-oxyethyl phosphorylcholine polymer. Chronic animal experiments were performed in nine calves. Three of the nine calves were excluded from analysis for problems with the circuit. Five of the six (83.3%) completed the 60 day duration of the study, while one prematurely died of massive bleeding due to inflow port detachment. The pump did not stop due to magnetic-levitation malfunction. Neither pump thrombosis nor major organ infarction was observed at autopsy. In comparison to machined surfaces, the injection-molded pump surfaces were thrombus-free after 60 day implantation. This study demonstrates the feasibility of MedTech Mag-Lev VAD for 60 day circulatory support.

  3. Method and apparatus for reducing axial thrust in centrifugal pumps

    NASA Astrophysics Data System (ADS)

    Palmer, Alan S.; Henry, John W., IV; Kerr, John P.

    1994-06-01

    A control stator comprising a plurality of stationary vanes, ribs, or cavities is provided in a centrifugal pump having a shrouded impeller. The function of the control stator is to slow the swirl of fluid in the cavity between the casing and the impeller front shroud and thereby provide a very cost effective solution to the problem of excess axial thrust. The control stator is a simple, inexpensive non-rotating part that can be affixed in an existing space in the pump casing between the casing wall and the front shroud of the impeller.

  4. Development of an autoflow cruise control system for a centrifugal pump.

    PubMed

    Nishida, H; Beppu, T; Nakajima, M; Nishinaka, T; Nakatani, H; Ihashi, K; Katsumata, T; Kitamura, M; Aomi, S; Endo, M

    1995-07-01

    To improve the ease of driving a centrifugal pump that is afterload dependent, we have developed an automatic flow control system for the Terumo Capiox centrifugal pump system. This system consists of an autoflow cruise control system with a safety cutoff. The Capiox Pump Console 3000 was controlled by a personal computer through a serial communication line. In the usual manual mode, the motor speed knob works as a pump speed control, and in the autoflow mode, the same knob works as a blood flow rate control. After selecting and obtaining the desired flow rate, the mode was changed from manual to autoflow mode. In the autoflow mode, the computer compares the desired flow rate with the actual flow measured by an ultrasonic Doppler flowmeter and adjusts the motor rotational speed accordingly. During both in vivo and in vitro testing, this autoflow mode was able to return the changed flow that was disrupted by either clamping and declamping of the tubing or by the bolus injection of a vasomotor drug to the selected flow rate within 10 s without any significant fluctuation. In conclusion, the newly developed computer controlled autoflow system was able to produce a reliable and effective flow regulation for a centrifugal pump.

  5. Influence of blade angle distribution along leading edge on cavitation performance of a centrifugal pump

    NASA Astrophysics Data System (ADS)

    Xu, Y.; Tan, L.; Cao, S. L.; Wang, Y. C.; Meng, G.; Qu, W. S.

    2015-01-01

    The influence of blade angle distribution along leading edge on cavitation performance of centrifugal pumps is analysed in the present paper. Three sets of blade angle distribution along leading edge for three blade inlet angles are chosen to design nine centrifugal pump impellers. The RNG k-epsilon turbulence model and the Zwart-Gerber-Belamri cavitation model are employed to simulate the cavitation flows in centrifugal pumps with different impellers and the same volute. The numerical results are compared with the experimental data, and the comparison proves that the numerical simulation can accurately predict the cavitation performance of centrifugal pumps. On the basis of the numerical simulations, the pump head variations with pump inlet pressure, and the flow details in centrifugal pump are revealed to demonstrate the influence of blade angle distribution along leading edge on cavitation performances of centrifugal pumps.

  6. Modelling of flow with cavitation in centrifugal pump

    NASA Astrophysics Data System (ADS)

    Homa, D.; Wróblewski, W.

    2014-08-01

    The paper concerns flow modelling in centrifugal pump with special consideration of cavitation phenomena. Cavitation occurs when local pressure drops below the saturation pressure according to the temperature of the flow. Vapour bubbles are created and then they flow through the areas with higher pressure. The bubbles collapse rapidly generating pressure wave, noise and vibration. Working under cavitation condition is very dangerous to a pump and can significantly shorten its lifetime. The investigated centrifugal pump consists of three two-flow rotors and stators working on a single shaft. The modelling process started with grid independence study. When the grid was chosen, the pump performance curve was obtained using the single phase fluid model. Next, using the results from pump performance curve calculations, the cavitation characteristic was obtained. The constant capacity was held when the pressure at the inlet was reduced. The two - phase model was used with Zwart cavitation model. The results indicate that the pump work in safe range of parameters. The analysis also provides wide range of information about the areas of vapour appearance. The most endangered regions are leading edges of rotor. When pressure at the inlet drops to about one third of pressure that calculations started from the cavitation cloud appears in whole rotor. The intense of vapour bubbles creation is greater near the shroud of the pump, rather than near the hub. As cavitation is strongly unsteady phenomena, the transient calculations were performed to check if the results are close to those obtained using the steady state type. The differences are not significant.

  7. Active magnetic bearings: As applied to centrifugal pumps

    NASA Astrophysics Data System (ADS)

    Nelik, Lev; Cooper, Paul; Jones, Graham; Galecki, Dennis; Pinckney, Frank; Kirk, Gordon

    1992-05-01

    Application of magnetic bearings to boiler feed pumps presents various attractive features, such as longer bearing life, lower maintenance costs, and improved operability through control of the rotordynamics. Magnetic bearings were fitted to an eight-stage, 600 hp boiler feed pump, which generates 2600 ft of heat at 680 gpm and 3560 rpm. In addition to the varied and severe operating environment in steady state operation of this pump in a power plant, it is also subjected to transient loads during frequent starts and stops. These loads can now be measured by the in-built instrumentation of the magnetic bearings. Following site installation, a follow-up bearing tune-up was performed, and pump transient response testing was conducted. The bearing response was completely satisfactory, ensuring trouble-free pump operation even in the range of reduced load. The experience gained so far through design and testing proves feasibility of magnetic bearings for boiler feed pumps, which sets the stage for application of even higher energy centrifugal pumps equipped with magnetic bearings.

  8. Active magnetic bearings: As applied to centrifugal pumps

    NASA Technical Reports Server (NTRS)

    Nelik, Lev; Cooper, Paul; Jones, Graham; Galecki, Dennis; Pinckney, Frank; Kirk, Gordon

    1992-01-01

    Application of magnetic bearings to boiler feed pumps presents various attractive features, such as longer bearing life, lower maintenance costs, and improved operability through control of the rotordynamics. Magnetic bearings were fitted to an eight-stage, 600 hp boiler feed pump, which generates 2600 ft of heat at 680 gpm and 3560 rpm. In addition to the varied and severe operating environment in steady state operation of this pump in a power plant, it is also subjected to transient loads during frequent starts and stops. These loads can now be measured by the in-built instrumentation of the magnetic bearings. Following site installation, a follow-up bearing tune-up was performed, and pump transient response testing was conducted. The bearing response was completely satisfactory, ensuring trouble-free pump operation even in the range of reduced load. The experience gained so far through design and testing proves feasibility of magnetic bearings for boiler feed pumps, which sets the stage for application of even higher energy centrifugal pumps equipped with magnetic bearings.

  9. Development of a centrifugal pump with improved antithrombogenicity and hemolytic property for chronic circulatory support.

    PubMed

    Taenaka, Y; Wakisaka, Y; Masuzawa, T; Tatsumi, E; Toda, K; Miyazaki, K; Eya, K; Baba, Y; Nakatani, T; Ohno, T; Nishimura, T; Takano, H

    1996-06-01

    A centrifugal pump with a unique structure has been developed for chronic support. The pump is driven by a magnetic coupling and has no rotating shaft, no seal around the rotating part, and a balancing hole at the center of the impeller and the thrust bearing. The pump was improved in stepwise fashion to realize good antithrombogenicity and low hemolysis. The first pump, the National Cardiovascular Center (NCVC)-0, had an impeller with 4 rectangular and curved vanes; 6 triangularly shaped curved vanes were employed in the second model, the NCVC-1, to reduce trauma to the blood. In the third design, the NCVC-2, the central hole was enlarged, and the thrust bearing shoulder was rounded so that blood washing was enhanced around the impeller; stream lines also were smoothed for improved antithrombogenicity. The hemolytic property of the device was evaluated in vitro with heparinized fresh goat blood; hemolysis indexes of the NCVC-0, -1, and -2 were 0.05, 0.01, and 0.006 g per 100 L, respectively. Antithrombogenicity of the pumps was examined in animal experiments as a left heart bypass device in goals weighing 52-75 kg. Six NCVC-0 pumps were driven for 14 to 33 (22.0 +/- 7.6) days in goats receiving the antiplatelet drug cilostazol orally. Four NCVC-1 pumps ran for 1 to 80 (28.5 +/- 30.6) days with the same drug regimen in 2 cases and with no anticoagulation therapy in 2 cases. After 3 preliminary 1-week tests of NCVC-2 pumps in animals, the pump was installed in 3 goats; 2 pumps were still running on the 182nd and 58th pumping day. Intracorporeal implantation also was attempted successfully. The results indicate that this pump has promising features for chronic support although longer term and additional evaluations are necessary.

  10. Cavitation Performance of a Centrifugal Pump with Water and Mercury

    NASA Technical Reports Server (NTRS)

    Hammitt, F. G.; Barton, R. K.; Cramer, V. F.; Robinson, M. J.

    1961-01-01

    The cavitation performance of a given centrifugal pump with water (hot and cold) and mercury is compared. It is found that there are significant scale effects with all fluids tested, with the Thoma cavitation parameter decreasing in all cases for increased pump speed or fluid Reynolds' number. The data for a fixed flow coefficient fall into a single curve when plotted against pump speed (or fluid velocity), rather than against Reynolds' number. Conversely, the Thoma parameter for a given Reynolds' number is approximately twice as large for mercury as for water. The direction of this variation is as predicted from consideration of the cavitation thermodynamic parameters which vary by a factor of 10(exp 7) between these fluids. No difference in cavitation performance between hot and cold water (approximately 160 F and 80 F) was observed, However, the thermodynamic parameters vary only by a factor of 5.

  11. Study of blade clearance effects on centrifugal pumps

    NASA Technical Reports Server (NTRS)

    Hoshide, R. K.; Nielson, C. E.

    1972-01-01

    A program of analysis, design, fabrication, and testing has been conducted to develop and experimentally verify analytical models to predict the effects of impeller blade clearance on centrifugal pumps. The effect of tip clearance on pump efficiency, and the relationship between the head coefficient and torque loss with tip clearance was established. Analysis were performed to determine the cost variation in design, manufacture, and test that would occur between unshrouded and shrouded impellers. An impeller, representative of typical rocket engine impellers, was modified by removing its front shroud to permit variation of its blade clearances. It was tested in water with special instrumentation to provide measurements of blade surface pressures during operation. Pump performance data were obtained from tests at various impeller tip clearances. Blade pressure data were obtained at the nominal tip clearance. Comparisons of predicted and measured data are given.

  12. Internal hydraulic loss in a seal-less centrifugal Gyro pump.

    PubMed

    Makinouchi, K; Ohara, Y; Sakuma, I; Damm, G; Mizuguchi, K; Jikuya, T; Takatani, S; Noon, G P; Nosé, Y

    1994-01-01

    A new index "loss factor Z" defined by Eq. 1 was introduced as the absolute expression of the mock loop resistance for testing a nonpulsatile pump. [formula: see text] where gamma is specific gravity of the fluid, g is the acceleration of gravity, delta P is total pressure head, and Q is flow. Z is expected to be constant, regardless of the pumping parameters. Z values obtained in the same mock loop but with different rotary blood pumps were almost identical and were defined as Z0. New methods of analysis of the flow-restrictive conditions of various rotary blood pumps are proposed in this paper: namely, differential loss factor delta Z, and loss factor sensitivity delta Z/delta A. The proposed Z-Q curves demonstrated better performance mapping than the conventional delta P-Q curves. Delta Z is the difference between the Z-Q curves of two different pumps. A is a design parameter of the pump; therefore delta Z/delta A is a quantitative expression of the effect of the design change on the hydraulic performance. These various indices were used to analyze the internal hydraulic loss of a centrifugal pump (Gyro pump). The relationship between its gap size (rotor casing) and hydraulic performance was assessed quantitatively by these indices. In this paper, the derivation processes and above-mentioned indices are described.

  13. Antithrombogenic properties of a monopivot magnetic suspension centrifugal pump for circulatory assist.

    PubMed

    Yamane, Takashi; Maruyama, Osamu; Nishida, Masahiro; Kosaka, Ryo; Chida, Takahiro; Kawamura, Hiroshi; Kuwana, Katsuyuki; Ishihara, Kazuhiko; Sankai, Yoshiyuki; Matsuzaki, Mio; Shigeta, Osamu; Enomoto, Yoshiharu; Tsutsui, Tatsuo

    2008-06-01

    The National Institute of Advanced Industrial Science and Technology (AIST) monopivot magnetic suspension centrifugal pump (MC105) was developed for open-heart surgery and several weeks of circulatory assist. The monopivot centrifugal pump has a closed impeller of 50 mm in diameter, supported by a single pivot bearing, and is driven through a magnetic coupling to widen the fluid gap. Design parameters such as pivot length and tongue radius were determined through flow visualization experiments, and the effectiveness was verified in preliminary animal experiments. The maximum overall pump efficiency reached 18%, and the normalized index of hemolysis tested with bovine blood was as low as 0.0013 g/100 L. Animal experiments with MC105 were conducted in sheep for 3, 15, 29, and 35 days in a configuration of left ventricle bypass. No thrombus was formed around the pivot bearing except when the pump speed was reduced by 20% of normal operational speed, which reduced the pump flow by 40% to avoid inlet suction. Subsequently, the antithrombogenic design was verified in animal experiments for 5 weeks at a minimum rotational speed of greater than 1500 rpm and a minimum pump flow greater than 1.0 L/min; no thrombus formation was observed under these conditions.

  14. Afterload-dependent flow fluctuation of centrifugal pump: should it be actively fixed?

    PubMed

    Nishida, H; Akazawa, T; Nishinaka, T; Aomi, S; Endo, M; Koyanagi, H

    1998-05-01

    To evaluate the clinical meaning and effects of afterload-dependent flow fluctuation in a centrifugal pump, concomitant measurement of flow rate and mixed venous oxygen saturation (SVO2) was performed in 5 cases of open heart surgery in which the patients underwent cardiopulmonary bypass (CPB) with the Terumo Capiox centrifugal pump. Continuous measurement of SVO2 using the 3M CDI System 100 was performed with a disposable cuvette incorporated into the drainage circuit. After the target flow rate of 2.4 L/min/m2 was obtained under a nonbeating condition, the pump rotational speed was fixed. During the cooling and low temperature period, SVO2 decreased as the flow rate spontaneously decreased but still stayed around 80% even with a 15-20% decrease in blood flow rate. This indicates that a luxury perfusion condition is ensured as long as the body temperature is kept low. In contrast, during the rewarming period, SVO2 decreased to around 70-75% despite a 15-25% spontaneous increase in flow rate. Although this level of SVO2 still indicates adequate systemic perfusion, there is a possibility of regional hypoperfusion in patients with such conditions as cerebrovascular disease. In conclusion, although diligent adjustment of the physiological fluctuating flow rate in the centrifugal pump seems unnecessary during conventional open heart surgery, manual control may be necessary especially during the rewarming period, normothermic surgery, or circulatory assist for shocked patients. From this study, we also conclude that the major benefit of the afterload-independent autoflow control system of the centrifugal pump is the improvement of safety in terms of the fixed reservoir level and the handling of cardiopulmonary bypass.

  15. Turbine blood pumps.

    PubMed

    Noon, G P; Morley, D; Irwin, S; Abdelsayed, S; Benkowski, R; Lynch, B E

    2001-01-01

    After years of development and preclinical testing, clinical trials of the MicroMed DeBakey VAD began in November 1998 in Europe and in June 2000 in the United States. As of August 2000, 44 patients in Europe and 3 patients in the United States have undergone implantation with the MicroMed DeBakey VAD. In conclusion, data from the European clinical trial of the MicroMed DeBakey VAD support the safety and performance of the device. Results show that the device provides adequate left ventricular and circulatory support in patients with end-stage heart failure without unduly jeopardizing patient safety. Moreover, the device provides advantages not inherent to commercially available pulsatile devices: (1) miniature size, enabling implantation in smaller patients; (2) ease of implantation; (3) reduced surgical bleeding; and (4) a low incidence of postoperative infections, often a limiting factor with other devices. The MicroMed DeBakey VAD European clinical trial is the first demonstration of the compatibility of continuous blood flow with adequate tissue perfusion and overall maintenance of life for up to 4.5 months. This initial experience with the MicroMed DeBakey VAD suggests that the pump can provide circulatory support to bridge patients to cardiac transplantation and may provide an improved quality of life for the patient with end-stage heart failure.

  16. Analyses of hydrodynamic radial forces on centrifugal pump impellers

    NASA Technical Reports Server (NTRS)

    Adkins, D. R.; Brennen, C. E.

    1988-01-01

    An experimental and theoretical study of the hydrodynamic interactions occurring between a centrifugal pump impeller and a volute is presented. The theoretical analysis provides a quasi-one-dimensional treatment of the flow in the volute, and it is extended to include the hydrodynamic force perturbations caused by the impeller whirling eccentrically in the volute. It is noted that these perturbations are often destabilizing. The theoretical models were found to accurately predict the radial forces caused by the flow through the impeller. The pressure acting on the front shroud of the impeller is shown to have a significant effect on the destabilizing hydrodyamic forces.

  17. Flow measurement at the pump head of centrifugal pumps: comparison of ultrasonic transit time and ultrasonic Doppler systems.

    PubMed

    Schima, H; Huber, L; Schmallegger, H; Drost, C J; Droudt, A; Wieselthaler, G; Losert, U

    1997-07-01

    Determination of blood flow is essential for monitoring rotary blood pumps. However, accurate measurement directly adjacent to the pump housing is difficult because of the highly irregular flow profiles near the fast spinning rotor. Therefore, a specially adapted flow probe based on the ultrasound transit time (USTT) principle was designed to evaluate the flow in centrifugal blood pumps. The probe can be directly mounted at the housing and creates 2 crossed measuring ultrasound beams. The mean value, Qm, of the 2 output signals corresponds to the blood flow and the difference, Qd, correlates to the vorticity of the flow profile in the pump outflow tract. In vitro measurements obtained an accuracy for mean flow values of better than +/-0.6 L/min in extreme working points and for vorticity values even as high as Qd = 3.5 L/min. Because of vorticity, however, the output signal contained considerable noise, and that required the application of a 10 Hz filter. Positioning of the ultrasound (US) beams parallel to the axial direction of the pump was superior to radial positioning. Additional measurement of the flow profile demonstrated that a large vorticity occurred (up to Qd equal to 3.5 L/min), and this vorticity was highly dependent upon the afterload of the pump. In vivo experiments demonstrated the reliability of the method. We concluded that USTT flow measurement can determine blood flow immediately adjacent to the pump housing with sufficient accuracy, and these measurements are superior to those from US-Doppler systems (which cannot handle the vorticity accurately enough) and electromagnetic devices (which lack zero stability).

  18. First experience with closed circuit/centrifugal pump extracorporeal circulation: cellular trauma, coagulatory, and inflammatory response.

    PubMed

    Just, Sören S; Müller, Torsten; Hartrumpf, Martin; Albes, Johannes M

    2006-10-01

    Closed circuit extracorporeal circulation comprising a centrifugal pump has been developed to reduce deleterious effects of standard cardiopulmonary bypass. This study compares such a system with standard extracorporeal circulation (ECC). Twenty patients underwent isolated routine coronary artery revascularization. Ten patients underwent ECC. Ten patients were operated upon using a closed circuit/centrifugal pump system with coated surfaces (ISS) (SYNERGY, Stöckert). Both groups did not differ regarding age, body mass, left ventricular function, number of bypasses, and concomitant diseases. Free hemoglobin (fHb), plasmin-antiplasmin complex (PAPc), platelet function (ROTEG), and interleukin 6 (IL-6) were measured preoperatively, intraoperatively (after sternotomy, during X-Clamp, during reperfusion, post ECC or ISS), and postoperatively. Technical problems were not observed. The ISS group demonstrated significantly less fHb during bypass, a lower intraoperative myocardial damage as well as less increase in IL-6 after bypass and postoperatively compared to ECC. In ISS fluid balance was significantly lower than in ECC whereas drainage loss and hospitalization did not differ statistically. Extracorporeal circulation with a closed circuit/centrifugal pump system can be routinely employed and appears to be safe. Intraoperative and early postoperative reduction of red blood cell trauma and inflammation are of potential value.

  19. Clinical use of Jostra Rota Flow centrifugal pump: the first case report in Japan.

    PubMed

    Hata, M; Shiono, M; Orime, Y; Yagi, S; Yamamoto, T; Okumura, H; Kimura, S; Kashiwazaki, S; Choh, S; Negishi, N; Sezai, Y; Matsui, T; Suzuki, M

    1999-08-01

    A Jostra Rota Flow centrifugal blood pump was clinically applied for a cardiopulmonary bypass (CPB) of an ascending aortic replacement for type A aortic dissection. The patient was a 68-year-old female with Stanford type A, DeBakey type II thrombosed aortic dissection complicated by cardiac tamponade and moderate aortic regurgitation. The surgery was carried out on December 22, 1998. The air inside the pump was easily and quickly removed, and its mode of control was excellent. The pump flow during the operation was maintained at about 2.2 l/m2. Total CPB time was 179 minutes. Macroscopically and microscopically, there were no thrombi inside the pump, after usage. The postoperative course was uneventful. The clinical use of this pump was the first case in Japan. This pump is excellent in the ease by which it's controlled due to its compact size and low weight. Furthermore, the Rota Flow console can be fully integrated in the HL-20 heart-lung machine, and these systems have pulsatile flow mode possibility. This pump is suitable not only for the main pump of CPB but also circulatory support.

  20. Evaluation of a multiple disk centrifugal pump as an artificial ventricle.

    PubMed

    Miller, G E; Sidhu, A; Fink, R; Etter, B D

    1993-07-01

    A multiple-disk centrifugal pump based on the Tesla Turbine design has been modified for potential use as an artificial ventricle or ventricular assist device. The pump consists of a series of interconnected parallel disks placed within a spiral volute housing. This pump normally operates as a continuous flow device; however, a controller circuit has been developed to also allow for pulsatile operation. Frequency, systolic duration, systolic rise time, and diastolic decay time can be independently controlled to produce a wide range of pulsatile pressures and flows. This pumping system was tested in vitro on a mock circulatory system using a blood analogue. Inlet and outlet pressures, outlet flow, and motor rotations per minute were continually monitored over a wide range of physiologic operating conditions. The disk pump output was compared with that of other artificial ventricles and produced favorable results. Direct experimental comparisons were made with a Harvard Apparatus pulsatile piston pump. Unlike the Harvard pump, the disk pump does not use valves. Rather, a slight forward rotation of the disks is used to offset the adverse diastolic pressure gradient, which avoids backflow through the device.

  1. Axial and centrifugal continuous-flow rotary pumps: a translation from pump mechanics to clinical practice.

    PubMed

    Moazami, Nader; Fukamachi, Kiyotaka; Kobayashi, Mariko; Smedira, Nicholas G; Hoercher, Katherine J; Massiello, Alex; Lee, Sangjin; Horvath, David J; Starling, Randall C

    2013-01-01

    The recent success of continuous-flow circulatory support devices has led to the growing acceptance of these devices as a viable therapeutic option for end-stage heart failure patients who are not responsive to current pharmacologic and electrophysiologic therapies. This article defines and clarifies the major classification of these pumps as axial or centrifugal continuous-flow devices by discussing the difference in their inherent mechanics and describing how these features translate clinically to pump selection and patient management issues. Axial vs centrifugal pump and bearing design, theory of operation, hydrodynamic performance, and current vs flow relationships are discussed. A review of axial vs centrifugal physiology, pre-load and after-load sensitivity, flow pulsatility, and issues related to automatic physiologic control and suction prevention algorithms is offered. Reliability and biocompatibility of the two types of pumps are reviewed from the perspectives of mechanical wear, implant life, hemolysis, and pump deposition. Finally, a glimpse into the future of continuous-flow technologies is presented.

  2. Sound generation by a centrifugal pump at blade passing frequency

    SciTech Connect

    Morgenroth, M.; Weaver, D.S.

    1996-12-01

    This paper reports the results of an experimental study of the pressure pulsations produced by a centrifugal volute pump at its blade passing frequency and their amplification by acoustic resonance in a connected piping system. Detailed measurements were made of the pressure fluctuations in the piping as a function of pump speed and flow rate. A semi-empirical model was used to separate acoustic standing waves from hydraulic pressure fluctuations. The effects of modifying the cut-water geometry were also studied, including the use of flow visualization to observe the flow behavior at the cut-water. The results suggest that the pump may act as an acoustic pressure or velocity source, depending on the flow rate. At conditions of acoustic resonance, the pump acted as an open termination of the piping, i.e., as a node in the acoustic pressure standing waves. Rounding the cut-water had the effect of reducing the amplitude of acoustic resonance, apparently because of the ability of the stagnation point to move and thereby reduce the vorticity generated. A notable example of this acoustic resonance in the Primary Heat Transport (PHT) system at Ontario Hydro`s Darlington nuclear power station.

  3. Influence of clearance model on numerical simulation of centrifugal pump

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Gao, B.; Yang, L.; Du, W. Q.

    2016-05-01

    Computing models are always simplified to save the computing resources and time. Particularly, the clearance that between impeller and pump casing is always ignored. But the completer model is, the more precise result of numerical simulation is in theory. This paper study the influence of clearance model on numerical simulation of centrifugal pump. We present such influence via comparing performance, flow characteristic and pressure pulsation of two cases that the one of two cases is the model pump with clearance and the other is not. And the results show that the head decreases and power increases so that efficiency decreases after computing with front and back cavities. Then no-leakage model would improve absolute velocity magnitude in order to reach the rated flow rate. Finally, more disturbance induced by front cavity flow and wear-ring flow would change the pressure pulsation of impeller and volute. The performance of clearance flow is important for the whole pump in performance, flow characteristic, pressure pulsation and other respects.

  4. RELATIONSHIP BETWEEN VIBRATIONS AND MECHANICAL SEAL LIFE IN CENTRIFUGAL PUMPS

    SciTech Connect

    Leishear, R; Jerald Newton, J; David Stefanko, D

    2007-04-30

    A reduction of vibrations in mechanical seals increases the life of the seals in centrifugal pumps by minimizing fatigue damage. Mechanical seals consist of two smooth seal faces. one face is stationary with respect to the pump. The other rotates. Between the faces a fluid film evaporates as the fluid moves radially outward across the seal face. ideally, the film evaporates as it reaches the outer surface of the seal faces, thereby preventing leakage from the pump and effectively lubricating the two surfaces. Relative vibrations between the two surfaces affect the fluid film and lead to stresses on the seal faces, which lead to fatigue damage. As the fluid film breaks down impacts between the two seal faces create tensile stresses on the faces, which cycle at the speed of the motor rotation. These cyclic stresses provide the mechanism leading to fatigue crack growth. The magnitude of the stress is directly related to the rate of crack growth and time to failure of a seal. Related to the stress magnitude, vibration data is related to the life of mechanical seals in pumps.

  5. Mechanical drive for blood pump

    DOEpatents

    Bifano, N.J.; Pouchot, W.D.

    1975-07-29

    This patent relates to a highly efficient blood pump to be used as a replacement for a ventricle of the human heart to restore people disabled by heart disease. The mechanical drive of the present invention is designed to operate in conjunction with a thermoelectric converter power source. The mechanical drive system essentially converts the output of a rotary power into pulsatile motion so that the power demand from the thermoelectric converter remains essentially constant while the blood pump output is pulsed. (auth)

  6. Baylor Gyro Pump: a completely seal-less centrifugal pump aiming for long-term circulatory support.

    PubMed

    Ohara, Y; Sakuma, I; Makinouchi, K; Damm, G; Glueck, J; Mizuguchi, K; Naito, K; Tasai, K; Orime, Y; Takatani, S

    1993-07-01

    A seal-less centrifugal pump aiming for long-term circulatory support has been developed. In this model, shaft seals that cause thrombus formation and blood leakage were eliminated. A brushless direct current motor was incorporated as a driving unit, and pivot bearings were used to support the impeller. With reference to its motor-driven system, this pump was named the M-Gyro Pump. The first model (M1) yielded an index of hemolysis of 0.005 g/100 L using bovine blood and demonstrated satisfactory performance as a right heart assist for 2 days (4 L/min, 60 mm Hg, 1,800 rpm). The second model (M2) has been developed for left heart assist by employing a stronger motor. The pump capacity was improved to 6 L/min against 240 mm Hg at 1,800 rpm, but significant heat generation was observed. By optimization of motor efficiency, the M2 model can be improved to meet the requirements of a pump for left heart assist.

  7. An implantable seal-less centrifugal pump with integrated double-disk motor.

    PubMed

    Schima, H; Schmallegger, H; Huber, L; Birgmann, I; Reindl, C; Schmidt, C; Roschal, K; Wieselthaler, G; Trubel, W; Losert, U

    1995-07-01

    Thrombus formation and sealing problems at the shaft as well as the compact and efficient design of the driving unit have been major difficulties in the construction of a long-term implantable centrifugal pump. To eliminate the problems of the seal, motor size, and efficiency, two major steps were taken by modifying the Vienna implantable centrifugal pump. First, a special driving unit was developed, in which the permanent magnets of the motor themselves are used for coupling the force into the rotor. Second, the rotor shaft in the pumping chamber was eliminated by adopting a concept recently presented by Ohara. The rotor is supported by 3 pins, which run on a carbon disk, whose concave shape leads to stabilization. The device has the following specifications: size: 65 mm (diameter) by 35 mm (height), 101 cm3; priming volume 30 cm3, 240 g; and a 6-pole brushless double disk DC motor. The required input power of the described prototype is 15 W at 150 mm Hg, 5 L/min (overall eta = 11%), and has an in vitro index of hemolysis (IH) of 0.0046 g/100 L. The test for in vitro thrombus growth exhibited far less thrombus formation in the new design than in designs with axles. In conclusion, the design of a special driving unit and the elimination of the axle led to the construction of a small pump with very low blood traumatization.

  8. Improvement of hemocompatibility for hydrodynamic levitation centrifugal pump by optimizing step bearings.

    PubMed

    Kosaka, Ryo; Yada, Toru; Nishida, Masahiro; Maruyama, Osamu; Yamane, Takashi

    2011-01-01

    We have developed a hydrodynamic levitation centrifugal blood pump with a semi-open impeller for a mechanically circulatory assist. The impeller levitated with original hydrodynamic bearings without any complicated control and sensors. However, narrow bearing gap has the potential for causing hemolysis. The purpose of the study is to investigate the geometric configuration of the hydrodynamic step bearing to minimize hemolysis by expansion of the bearing gap. Firstly, we performed the numerical analysis of the step bearing based on Reynolds equation, and measured the actual hydrodynamic force of the step bearing. Secondly, the bearing gap measurement test and the hemolysis test were performed to the blood pumps, whose step length were 0 %, 33 % and 67 % of the vane length respectively. As a result, in the numerical analysis, the hydrodynamic force was the largest, when the step bearing was around 70 %. In the actual evaluation tests, the blood pump having step 67 % obtained the maximum bearing gap, and was able to improve the hemolysis, compared to those having step 0% and 33%. We confirmed that the numerical analysis of the step bearing worked effectively, and the blood pump having step 67 % was suitable configuration to minimize hemolysis, because it realized the largest bearing gap.

  9. Small centrifugal pumps for low-thrust rocket engines

    NASA Technical Reports Server (NTRS)

    Furst, R. B.

    1986-01-01

    Six small, low specific speed centrifugal pump configurations were designed, fabricated, and tested. The configurations included shrouded, and 25 and 100% admission open face impellers with 2 inch tip diameters; 25, 50, and 100% emission vaned diffusers; and volutes with conical exits. Impeller tip widths varied from 0.030 inch to 0.052 inch. Design specific speeds (N sub s = RPM*GPM**0.5.FT**0.75) were 430 (four configurations) and 215 (two configurations). The six configurations were tested with water as the pumped fluid. Noncavitating performance results are presented for the design speed of 24,500 rpm over a flowrate range from 1 to 6 gpm for the N sub s = 430 configurations and test speeds up to 29,000 rpm over a flowrate range from 0.3 to 1.2 gpm for the N sub s = 215 configurations. Cavitating performance results are presented over a flowrate range from 60 to 120% of design flow. Fabrication of the small pump conponents is also discussed.

  10. Origins of hydrodynamic forces on centrifugal pump impellers

    NASA Technical Reports Server (NTRS)

    Adkins, Douglas R.; Brennen, Christopher E.

    1987-01-01

    Hydrodynamic interactions that occur between a centrifugal pump impeller and volute are experimentally and theoretically investigated. The theoretical analysis considers the inability of the blades to perfectly guide the flow through the impeller, and also includes a quasi-one dimensional treatment of the flow in the volute. The disturbance at the impeller discharge and the resulting forces are determined by the theoretical model. The model is then extended to obtain the hydrodynamic force perturbations that are caused by the impeller whirling eccentrically in the volute. Under many operating conditions, these force perturbations were found to be destablizing. Comparisons are made between the theoretical model and the experimental measurements of pressure distributions and radial forces on the impeller. The theoretical model yields fairly accurate predictions of the radial forces caused by the flow through the impeller. However, it was found that the pressure acting on the front shroud of the impeller has a substantial effect on the destablizing hydrodynamic forces.

  11. Research on energy conversion mechanism of rotodynamic pump and design of non-overload centrifugal pump

    NASA Astrophysics Data System (ADS)

    Zhang, X. L.; Hu, S. B.; Shen, Z. Z.; Wu, S. P.; Li, K.

    2016-05-01

    In this paper, an attempt has been made for the calculation of an expression for the intrinsic law of input power which has not yet been given by current theory of Rotodynamic pump. By adequate recognition of the characteristics of non-inertial system within the rotating impeller, it is concluded that the input power consists of two power components, the first power component, whose magnitude increases with the increase of the flow rate, corresponds to radial velocity component, and the second power component, whose magnitude decreases with the increase of the flow rate, corresponds to tangential velocity component, therefore, the law of rise, basic levelness and drop of input power curves of centrifugal pump, mixed-flow pump and axial-flow pump can be explained reasonably. Through further analysis, the main ways for realizing non-overload of centrifugal pump are obtained, and its equivalent design factor is found out, the factor correlates with the outlet angle of leading face and back face of the blade, wrap angle, number of blades, outlet width, area ratio, and the ratio of operating flow rate to specified flow rate and so on. These are verified with actual example.

  12. Effect of several centrifugal pump passages on the viability and activity of Steinernema carpocapsae, a biopesticide.

    PubMed

    Brusselman, Eva; Nuyttens, David; De Sutter, Nancy; Viaene, Nicole; Steurbaut, Walter; Moens, Maurice

    2008-01-01

    The effect of several passages through a centrifugal pump on the viability and activity of Steinernema corpocapsoe was investigated. A tendency of reduced viability was detected after 10 passages through the centrifugal pump, but the difference was not statistically significant. Activity decreased significantly from 91.9% to 83.6%. The experimental set-up was chosen to eliminate temperature increase. Therefore, the results prove that mechanical pump damage cannot be excluded as the cause of EPN damage during spray application.

  13. Numerical simulation of flow in centrifugal pump with complex impeller

    NASA Astrophysics Data System (ADS)

    Cui, Bao-ling; Lin, Yong-gang; Jin, Ying-zi

    2011-03-01

    Based on the Navier-Stokes equations and the Spalart-Allmaras turbulence model, three dimensional turbulent flow fields in centrifugal pump with long-mid-short blade complex impeller are calculated and analyzed numerically. The relative velocity and pressure distributions in the flowpart are obtained. It is found that the flow in the passage of the complex impeller is unsymmetrical due to the joint action between volute and impeller. The back-flow region is at inlet of long-blade suction side, near middle part of long-blade pressure side and outlet of short-blade suction side. The flow near volute throat is affected greatly by volute. The relative velocity is large and it is easy to bring back flow at outlet of the complex impeller near volute throat. The static and total pressure rise uniformly from inlet to outlet in the impeller. At impeller outlet, the pressure periodically decreases from pressure side to suction side, and then the static pressure sharply rise near the throat. The experimental results show that the back flow in the impeller has an important influence on the performance of pump.

  14. [A new approach for improving antithrombogenicity in centrifugal pump].

    PubMed

    Qian, Kunxi; Zeng, Pei; Ru, Weimin; Yuan, Haiyu

    2003-09-01

    For long-term application of the rotary pumps, it is necessary to solve the problems of bearing wear and thrombosis along the bearing. Currently, many investigators choose the magnetic bearing to realize zero-friction and no contact between the rotor and stator; the former avoids the mechanical wear and the latter eliminates the possibility of thrombus formation. We tried and found that it is difficult to apply a magnetic bearing to rotary pump without disturbing its simplicity, reliability and implantable; therefore, we have developed a much simpler and much more creative approach to achieving the same results. Instead of the sliding bearing, a rolling bearing has been devised for the pump; its friction is about 1/15 of the sliding bearing. Furthermore, a wear-proof material of ultra-high-molecular weight polythene has been adopted in making the rollers, their anti-wear property in 8 times better than that of metal. Thereby, the service life of the bearing has extended to several years. For preventing the thrombus formation along the bearing, the impeller reciprocation axially as the impeller changes its rotating speed periodically to produce a pulsatile flow. The reciprocation is a result of the effects of a magnetic force between the motor rotor and stator, and a hydraulic force between the blood flow and the impeller. Similar to piston pump, the oscillating impeller can make the blood in and out of the bearing, resulting in wash-out once a circle. This is obviously beneficial to preventing thrombosis along the bearing and in the pump. The endurance tests with saline of this novel pump demonstrated a durability of the device. It promises to be able to assist the circulation of the patients permanently and to be able to replace the heart transplantation in the future.

  15. Numerical studies in a centrifugal pump with the improved blade considering cavitation

    NASA Astrophysics Data System (ADS)

    Song, P. F.; Zhang, Y. X.; Xu, C.; Zhou, X.; Zhang, J. Y.

    2015-01-01

    In this paper, a centrifugal pump with the improved blade for cavitation is studied numerically. A 3D impeller with logarithmic spiral blade profile was designed by the in-house hydraulic design code using a centrifugal pump geometric parameters, and the blade profile curve of suction side on the designed impeller is replaced by a combination of tangent line and circle arc line. The cavitation flows in the centrifugal pump with designed impeller, modified impeller and centrifugal pump spectrum impeller are respectively calculated by two-phase CFD simulation at three flow rates. The tests of the centrifugal pump have been conducted to verify numerical simulation. The effects of designed impeller and modified impeller on hydraulic efficiency, critical cavitation number, cavitation length, head drop performance and vapor cavity distribution in impeller are investigated. The results show that the modification of blade profile curve of suction side can improve the cavitation performance of an impeller and hydraulic efficiency of centrifugal pump. Compared with designed impeller, the critical cavitation number of centrifugal pump with modified impeller decrease by 26.5% under the same flow rate coefficient, and the cavitation intensity in the modified impeller is weakened effectively. The hydraulic efficiency of modified impeller also increases by 4.9%.

  16. Development of rotary blood pump technology: past, present, and future.

    PubMed

    Nosé, Y; Yoshikawa, M; Murabayashi, S; Takano, T

    2000-06-01

    Even though clinical acceptance of a nonpulsatile blood flow was demonstrated almost 45 years ago, the development of a nonpulsatile blood pump was completely ignored until 20 years ago. In 1979, the first author's group demonstrated that completely pulseless animals did not exhibit any abnormal physiology if 20% higher blood flows were provided to them. However, during the next 10 years (1979-1988), minimum efforts were provided for the development of a nonpulsatile, permanently implantable cardiac prosthesis. In 1989, the first author and his team at Baylor College of Medicine initiated a developmental strategy of various types of nonpulsatile rotary blood pumps, including a 2-day rotary blood pump for cardiopulmonary bypass application, a 2 week pump for ECMO and short-term circulatory assistance, a 2 year pump as a bridge to transplantation, and a permanently implantable cardiac prosthesis. Following the design and developmental strategy established in 1989, successful development of a 2-day pump (the Nikkiso-Fairway cardiopulmonary bypass pump) in 4 years (1989-1993), a 2 week pump (Kyocera gyro G1E3 pump) in 6 years (1992-1998), and a bridge to transplant pump (DeBakey LVAD-an axial flow blood pump) in 10 years (1988-1998) was made. Currently, a permanently implantable centrifugal blood pump development program is successfully completing its initial Phase 1 program of 5 years (1995-2000). Implantation exceeded 9 months without any negative findings. An additional 5 year Phase II program (2000-2005) is expected to complete such a device that will be clinically available.

  17. Circulatory assist with centrifugal pump as a bridge to recovery: mathematical analysis.

    PubMed

    Arpesella, G; Mikus, E; Arabia, M; Loforte, A; Mikus, P M

    2007-07-01

    Mechanical circulatory support is an essential issue in the management of patients with end-stage cardiac failure. The aim of this study is to evaluate the efficacy of temporary support with a centrifugal blood pump as bridge to heart function recovery or bridge to transplantation. Heart recovery is achieved by improving ventricular mechanical working conditions with proper modifications of preload and afterload. This article assesses the advantages of a novel 'cardiac chambers' cannulation setting versus the traditional one, in the case of biventricular or isolated right ventricular failure. The study was conducted using a numerical computer model based on the work by Guyton, Sagawa, Westerhof, and Noordergraaf. Simulation of the planned trials was achieved by changing the model parameters, the pump angular velocity, and the inflow and outflow settings.

  18. 21 CFR 864.9275 - Blood bank centrifuge for in vitro diagnostic use.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Blood bank centrifuge for in vitro diagnostic use... Manufacture Blood and Blood Products § 864.9275 Blood bank centrifuge for in vitro diagnostic use. (a) Identification. A blood bank centrifuge for in vitro diagnostic use is a device used only to separate blood...

  19. 21 CFR 864.9275 - Blood bank centrifuge for in vitro diagnostic use.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Blood bank centrifuge for in vitro diagnostic use... Manufacture Blood and Blood Products § 864.9275 Blood bank centrifuge for in vitro diagnostic use. (a) Identification. A blood bank centrifuge for in vitro diagnostic use is a device used only to separate blood...

  20. 21 CFR 864.9275 - Blood bank centrifuge for in vitro diagnostic use.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Blood bank centrifuge for in vitro diagnostic use... Manufacture Blood and Blood Products § 864.9275 Blood bank centrifuge for in vitro diagnostic use. (a) Identification. A blood bank centrifuge for in vitro diagnostic use is a device used only to separate blood...

  1. 21 CFR 864.9275 - Blood bank centrifuge for in vitro diagnostic use.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Blood bank centrifuge for in vitro diagnostic use... Manufacture Blood and Blood Products § 864.9275 Blood bank centrifuge for in vitro diagnostic use. (a) Identification. A blood bank centrifuge for in vitro diagnostic use is a device used only to separate blood...

  2. 21 CFR 864.9275 - Blood bank centrifuge for in vitro diagnostic use.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Blood bank centrifuge for in vitro diagnostic use... Manufacture Blood and Blood Products § 864.9275 Blood bank centrifuge for in vitro diagnostic use. (a) Identification. A blood bank centrifuge for in vitro diagnostic use is a device used only to separate blood...

  3. Numerical Study of a Fuel Centrifugal Pump with Variable Impeller Width for Aero-engines

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Guan, Huasheng; Ye, Zhifeng

    2015-12-01

    As typical pump with large flow rate and high reliability, centrifugal pumps in fuel system of aero-engines mostly regulate flow rate by flow bypass, which leads to low efficiency and large fuel temperature rise especially at low flow rate. An innovative fuel centrifugal pump with variable impeller width is a more effective way to regulate flow rate than flow bypass. To find external characteristics of the centrifugal pump with variable impeller width proposed in this paper, flow domain within the pump is simulated numerically and some primary performance parameters and their correlation are analyzed. Results show that flow rate of the pump can be regulated by variable impeller width and that efficiency for this scheme is higher than that for flow bypass. The higher outlet static pressure the pump runs at, the wider range of flow rates can be obtained with stronger nonlinear relationship between flow rate and impeller width.

  4. Optimization and analysis of centrifugal pump considering fluid-structure interaction.

    PubMed

    Zhang, Yu; Hu, Sanbao; Zhang, Yunqing; Chen, Liping

    2014-01-01

    This paper presents the optimization of vibrations of centrifugal pump considering fluid-structure interaction (FSI). A set of centrifugal pumps with various blade shapes were studied using FSI method, in order to investigate the transient vibration performance. The Kriging model, based on the results of the FSI simulations, was established to approximate the relationship between the geometrical parameters of pump impeller and the root mean square (RMS) values of the displacement response at the pump bearing block. Hence, multi-island genetic algorithm (MIGA) has been implemented to minimize the RMS value of the impeller displacement. A prototype of centrifugal pump has been manufactured and an experimental validation of the optimization results has been carried out. The comparison among results of Kriging surrogate model, FSI simulation, and experimental test showed a good consistency of the three approaches. Finally, the transient mechanical behavior of pump impeller has been investigated using FSI method based on the optimized geometry parameters of pump impeller.

  5. Optimization and Analysis of Centrifugal Pump considering Fluid-Structure Interaction

    PubMed Central

    Hu, Sanbao

    2014-01-01

    This paper presents the optimization of vibrations of centrifugal pump considering fluid-structure interaction (FSI). A set of centrifugal pumps with various blade shapes were studied using FSI method, in order to investigate the transient vibration performance. The Kriging model, based on the results of the FSI simulations, was established to approximate the relationship between the geometrical parameters of pump impeller and the root mean square (RMS) values of the displacement response at the pump bearing block. Hence, multi-island genetic algorithm (MIGA) has been implemented to minimize the RMS value of the impeller displacement. A prototype of centrifugal pump has been manufactured and an experimental validation of the optimization results has been carried out. The comparison among results of Kriging surrogate model, FSI simulation, and experimental test showed a good consistency of the three approaches. Finally, the transient mechanical behavior of pump impeller has been investigated using FSI method based on the optimized geometry parameters of pump impeller. PMID:25197690

  6. Roller and Centrifugal Pumps: A Retrospective Comparison of Bleeding Complications in Extracorporeal Membrane Oxygenation.

    PubMed

    Halaweish, Ihab; Cole, Adam; Cooley, Elaine; Lynch, William R; Haft, Jonathan W

    2015-01-01

    Centrifugal pumps are increasingly used for extracorporeal membrane oxygenation (ECMO) rather than roller pumps. However, shear forces induced by these types of continuousflow pumps are associated with acquired von Willebrand factor deficiency and bleeding complications. This study was undertaken to compare adverse bleeding complications with the use of centrifugal and roller pumps in patients on prolonged ECMO support. The records of all adult ECMO patients from June 2002 to 2013 were retrospectively reviewed using the University of Michigan Health System database and the Extracorporeal Life Support Organization registry, focusing on patients supported for at least 5 days. Ninety-five ECMO patients met criteria for inclusion (48 roller vs. 47 centrifugal pump). Indications included pulmonary (79%), cardiac (15%), and extracorporeal cardiopulmonary resuscitation (6%), without significant difference between the two groups. Despite lower heparin anticoagulation (10.9 vs. 13.7 IU/kg/hr) with centrifugal pumps, there was a higher incidence of nonsurgical bleeding (gastrointestinal, pulmonary, and neurological) in centrifugal pump patients (26.1 vs. 9.0 events/1,000 patient-days, p = 0.024). In conclusion, in our historical comparison, despite reduced anticoagulation, ECMO support using centrifugal pumps was associated with a higher incidence of nonsurgical bleeding. The mechanisms behind this are multifactorial and require further investigation.

  7. Development of small centrifugal pumps for an electric propellant pump system

    NASA Astrophysics Data System (ADS)

    Johnsson, Göran; Bigert, Mikael

    Small centrifugal pumps with low specific speeds have been designed, manufactured and performance tested at Volvo Flygmotor AB under a contract from the European Space Agency (ESA) over the period mid-1985 to mid-1988. The development of the pumps is a part of the work carried out to develop an Electric Propellant Pump System (EPPS) for the storable propellant monomethyl hydrazine (MMH) and nitrogen tetraoxide (NTO). Supporting technology development has been funded by the Swedish Delegation for Space Activities (DFR) and Swedish Space Corporation (SSC) together with Volvo Flygmotor. The main advantages of a typical EPPS communication satellite application are weight and volume reduction of the propellant system compared with a pressure-fed system. Active engine mixture ratio control and improved propellant utilization are also possible. Refuelling in space is another potential application where EPPS can be used. The development work was focused on communication satellite apogee propulsion and used the MBB 3 kN engine as reference. This paper presents the pump design and analyses and the results from the test campaigns of three different pump configurations, carried out with water as test liquid. The head rise, efficiency and suction performance together with other characteristics are also given. The planned next development step is to demonstrate pump performance in the propellants and primarily in NTO. The step is funded by (DFR)/(SSC) together with Volvo Flygmotor.

  8. Numerical experiment optimization to obtain the characteristics of the centrifugal pump steps package

    NASA Astrophysics Data System (ADS)

    Boldyrev, S. V.; Boldyrev, A. V.

    2014-12-01

    The numerical simulation method of turbulent flow in a running space of the working-stage in a centrifugal pump using the periodicity conditions has been formulated. The proposed method allows calculating the characteristic indices of one pump step at a lower computing resources cost. The comparison of the pump characteristics' calculation results with pilot data has been conducted.

  9. Development of the NEDO implantable ventricular assist device with Gyro centrifugal pump.

    PubMed

    Yoshikawa, M; Nonaka, K; Linneweber, J; Kawahito, S; Ohtsuka, G; Nakata, K; Takano, T; Schulte-Eistrup, S; Glueck, J; Schima, H; Wolner, E; Nosé, Y

    2000-06-01

    from 10.4 to 14.2 W as LVAS and 15.8 W as RVAS. All cases exhibited low hemolysis. The renal function and the liver function were maintained normally in all cases throughout these experimental periods. In the 2 RVAS cases, pulmonary function was normally maintained. No calves demonstrated thromboembolic signs or symptoms throughout the experiments except Case 1 with the plastic pump. However, in the plastic pump cases, bilateral renal infarction was suspected in 2 cases during necropsy whereas no abnormal findings were revealed in the titanium pump cases. There were also no blood clots inside the PI 700 series. As for the 601, the explanted pumps demonstrated slight thrombus formations at the top and bottom pivots except in 1 case. The Gyro PI series, especially the PI 700 series, demonstrated superior performance, biocompatibility, antithrombogenicity and low hemolysis. Also, the durability of the actuator was demonstrated. Based on these results, this titanium centrifugal pump is suitable as an implantable LVAS and RVAS. It is likely that the Gyro PI series is a feasible component of the BiVAS functional TAH.

  10. Method for Reducing Pumping Damage to Blood

    NASA Technical Reports Server (NTRS)

    Bozeman, Richard J., Jr. (Inventor); Akkerman, James W. (Inventor); Aber, Gregory S. (Inventor); VanDamm, George Arthur (Inventor); Bacak, James W. (Inventor); Svejkovsky, Robert J. (Inventor); Benkowski, Robert J. (Inventor)

    1997-01-01

    Methods are provided for minimizing damage to blood in a blood pump wherein the blood pump comprises a plurality of pump components that may affect blood damage such as clearance between pump blades and housing, number of impeller blades, rounded or flat blade edges, variations in entrance angles of blades, impeller length, and the like. The process comprises selecting a plurality of pump components believed to affect blood damage such as those listed herein before. Construction variations for each of the plurality of pump components are then selected. The pump components and variations are preferably listed in a matrix for easy visual comparison of test results. Blood is circulated through a pump configuration to test each variation of each pump component. After each test, total blood damage is determined for the blood pump. Preferably each pump component variation is tested at least three times to provide statistical results and check consistency of results. The least hemolytic variation for each pump component is preferably selected as an optimized component. If no statistical difference as to blood damage is produced for a variation of a pump component, then the variation that provides preferred hydrodynamic performance is selected. To compare the variation of pump components such as impeller and stator blade geometries, the preferred embodiment of the invention uses a stereolithography technique for realizing complex shapes within a short time period.

  11. Research on the effect of wear-ring clearances to the performance of centrifugal pump

    NASA Astrophysics Data System (ADS)

    Zhao, W. G.; Li, Y. B.; Wang, X. Y.; Sun, J. P.; Wu, G. X.

    2012-11-01

    In order to study the effect of wear-ring clearance on the performance of centrifugal pump, based on the Reynolds Time-Averaged N-S equations and RNG k-ε turbulence model, a centrifugal pump was simulated with three variable styles of the wear-rings: Only the clearance of the front wear-ring was changed, only the clearance of the back wear-ring was changed and both were changed. Numerical results agree well with the experimental results. In the three changing styles of the clearance, the variable of the clearance of front wear-ring has the most influence on the performance of centrifugal pump. The existence of wear-ring not only has an effect on the volumetric loss of the centrifugal pump, but also on the performance of the centrifugal pump. Relative to the experimental studies, numerical simulation methods have some advantages, such as low cost, fast and efficient, and easy to get the detailed structure of the internal flow characteristics, so it has been widely used in the fluid machinery study. In order to study the effect of wear-ring clearance on the performance of centrifugal pump, based on the Reynolds Time-Averaged N-S equations and RNG k-ε turbulence model, a centrifugal pump was simulated with three variable styles of the wear-rings: Only the clearance of the front wear-ring was changed, only the clearance of the back wear-ring was changed and both were changed. Numerical results agree well with the experimental results. In the three changing styles of the clearance, the variable of the clearance of front wear-ring has the most influence on the performance of centrifugal pump.

  12. Experimental study of characteristic curves of centrifugal pumps working as turbines in different specific speeds

    SciTech Connect

    Derakhshan, Shahram; Nourbakhsh, Ahmad

    2008-01-15

    Pump manufacturers do not normally provide the characteristic curves of their pumps working as turbines. Therefore, establishing a correlation between the performances of direct (pump) and reverse (turbine) modes is essential in selecting the proper machine. In this paper, several centrifugal pumps (N{sub s} < 60 (m, m{sup 3}/s)) were tested as turbines. Using experimental data, some relations were derived to predict the best efficiency point of a pump working as a turbine, based on pump hydraulic characteristics. Validity of the presented method was shown using some referenced experimental data. Two equations were presented to estimate the complete characteristic curves of centrifugal pumps as turbines based on their best efficiency point. Deviations of suggested method from experimental data were considered and discussed. Finally, a procedure was presented for selecting a suitable pump to work as a turbine in a small hydro-site. (author)

  13. Long-term in vivo left ventricular assist device study with a titanium centrifugal pump.

    PubMed

    Ohtsuka, G; Nakata, K; Yoshikawa, M; Mueller, J; Takano, T; Yamane, S; Gronau, N; Glueck, J; Takami, Y; Sueoka, A; Letsou, G; Schima, H; Schmallegger, H; Wolner, E; Koyanagi, H; Fujisawa, A; Baldwin, J C; Nosé, Y

    1998-01-01

    A totally implantable centrifugal artificial heart has been developed. The plastic prototype, Gyro PI 601, passed 2 day hemodynamic tests as a functional total artificial heart, 2 week screening tests for antithrombogenicity, and 1 month system feasibility. Based on these results, a metallic prototype, Gyro PI 702, was subjected to in vivo left ventricular assist device (LVAD) studies. The pump system employed the Gyro PI 702, which has the same inner dimensions and the same characteristics as the Gyro PI 601, including an eccentric inlet port, a double pivot bearing system, and a magnet coupling system. The PI 702 is driven with the Vienna DC brushless motor actuator. For the in vivo LVAD study, the pump actuator package was implanted in the preperitoneal space in two calves, from the left ventricular apex to the descending aorta. Case 1 achieved greater than 9 month survival without any complications, at an average flow rate of 6.6 L/min with 10.2 W input power. Case 2 was killed early due to the excessive growth of the calf, which caused functional obstruction of the inlet port. There was no blood clot inside the pump. During these periods, neither case exhibited any physiologic abnormalities. The PI 702 pump gives excellent results as a long-term implantable LVAD.

  14. On dimensionless parameters for generalization pressure head and flow rate characteristics of centrifugal disk pumps

    NASA Astrophysics Data System (ADS)

    Naumov, I. E.; Prikhodko, Yu. M.; Chekhov, V. P.; Fomichev, V. P.

    2012-03-01

    Experimental study was performed for operation of a centrifugal disk pump at atmospheric air pressure. The dimensionless parameters were developed for generalization of experimental data on flow rate and head of the pump. The method for calculation of a pumping curve and throttling characteristic was offered through use of semiemperical generalization formulas. The method ensures a good accuracy in calculations, which is proved by comparison of calculation and experimental data for the pump tested.

  15. Research on energy conversion mechanism of a screw centrifugal pump under the water

    NASA Astrophysics Data System (ADS)

    Quan, H.; Li, R. N.; Su, Q. M.; Han, W.; Cheng, X. R.; Shen, Z. J.

    2013-12-01

    In order to research screw centrifugal pump impeller power capability and energy conversion mechanism, we used Navier-Stokes equation and standard k-ε equation turbulence model on the basis of the Euler equations to carry out screw centrifugal pump internal flow numerical simulation. This was explored by simulating specific design conditions; the medium is water, variation of speed and pressure of flow filed under the action of the impeller, and the screw centrifugal impeller shroud line and wheel line segment take monitoring sites. The monitoring points are between dynamic head and static head change to analyze the energy conversion capability along the impeller corners of screw centrifugal pump. The results show that the energy of fluid of the screw centrifugal pump is provided by spiral segment, the spiral segment in front of the impeller has played a multi-level role, it has significant reference value to research the energy conversion mechanism of screw centrifugal pump under solid-liquid two phase.

  16. Optimization of Centrifugal Pump Characteristic Dimensions for Mechanical Circulatory Support Devices.

    PubMed

    Korakianitis, Theodosios; Rezaienia, Mohammad A; Paul, Gordon M; Rahideh, Akbar; Rothman, Martin T; Mozafari, Sahand

    2016-01-01

    The application of artificial mechanical pumps as heart assist devices impose power and size limitations on the pumping mechanism, and therefore requires careful optimization of pump characteristics. Typically new pumps are designed by relying on the performance of other previously designed pumps of known performance using concepts of fluid dynamic similarity. Such data are readily available for industrial pumps, which operate in Reynolds numbers region of 10. Heart assist pumps operate in Reynolds numbers of 10. There are few data available for the design of centrifugal pumps in this characteristic range. This article develops specific speed versus specific diameter graphs suitable for the design and optimization of these smaller centrifugal pumps concentrating in dimensions suitable for ventricular assist devices (VADs) and mechanical circulatory support (MCS) devices. A combination of experimental and numerical techniques was used to measure and analyze the performance of 100 optimized pumps designed for this application. The data are presented in the traditional Cordier diagram of nondimensional specific speed versus specific diameter. Using these data, nine efficient designs were selected to be manufactured and tested in different operating conditions of flow, pressure, and rotational speed. The nondimensional results presented in this article enable preliminary design of centrifugal pumps for VADs and MCS devices.

  17. Centrifugal pump and roller pump in adult cardiac surgery: a meta-analysis of randomized controlled trials.

    PubMed

    Saczkowski, Richard; Maklin, Michelle; Mesana, Thierry; Boodhwani, Munir; Ruel, Marc

    2012-08-01

    Centrifugal pump (CP) and roller pump (RP) designs are the dominant main arterial pumps used in cardiopulmonary bypass (CPB). Trials reporting clinical outcome measures comparing CP and RP are controversial. Therefore, a meta-analysis was undertaken to evaluate clinical variables from randomized controlled trials (RCTs). Keyword searches were performed on Medline (1966-2011), EmBase (1980-2011), and CINAHL (1981-2011) for studies comparing RP and CP as the main arterial pump in adult CPB. Pooled fixed-effects estimates for dichotomous and continuous data were calculated as an odds ratio and weighted-mean difference, respectively. The P value was utilized to assess statistical significance (P < 0.05) between CP and RP groups. Eighteen RCTs met inclusion criteria, which represented 1868 patients (CP = 961, RP = 907). The prevailing operation was isolated coronary artery bypass graft surgery (CP = 88%, RP = 87%). Fixed-effects pooled estimates were performed for end-of-CPB (ECP) and postoperative day one (PDO) for platelet count (ECP: P = 0.51, PDO: P = 0.16), plasma free hemoglobin (ECP: P = 0.36, PDO: P = 0.24), white blood cell count (ECP: P = 0.21, PDO: P = 0.66), and hematocrit (ECP: P = 0.06, PDO: P = 0.51). No difference was demonstrated for postoperative blood loss (P = 0.65) or red blood cell transfusion (P = 0.71). Intensive care unit length of stay (P = 0.30), hospital length of stay (P = 0.33), and mortality (P = 0.91) were similar between the CP and RP groups. Neurologic outcomes were not amenable to pooled analysis; nevertheless, the results were inconclusive. There was no reported pump-related malfunction or mishap. The meta-analysis of RCTs comparing CP and RP in adult cardiac surgery suggests no significant difference for hematological variables, postoperative blood loss, transfusions, neurological outcomes, or mortality.

  18. Hemocompatibility of Axial Versus Centrifugal Pump Technology in Mechanical Circulatory Support Devices.

    PubMed

    Schibilsky, David; Lenglinger, Matthias; Avci-Adali, Meltem; Haller, Christoph; Walker, Tobias; Wendel, Hans Peter; Schlensak, Christian

    2015-08-01

    The hemocompatible properties of rotary blood pumps commonly used in mechanical circulatory support (MCS) are widely unknown regarding specific biocompatibility profiles of different pump technologies. Therefore, we analyzed the hemocompatibility indicating markers of an axial flow and a magnetically levitated centrifugal device within an in vitro mock loop. The HeartMate II (HM II; n = 3) device and a CentriMag (CM; n = 3) adult pump were investigated in a human whole blood mock loop for 360 min using the MCS devices as a driving component. Blood samples were analyzed by enzyme-linked immunosorbent assay for markers of coagulation, complement system, and inflammatory response. There was a time-dependent activation of the coagulation (thrombin-antithrombin complexes [TAT]), complement (SC5b-9), and inflammation system (polymorphonuclear [PMN] elastase) in both groups. The mean value of TAT (CM: 4.0 μg/L vs. 29.4 μg/L, P < 0.001; HM II: 4.5 μg/L vs. 232.2 μg/L, P < 0.05) and PMN elastase (CM: 53.4 ng/mL vs. 253.8 ng/mL, P < 0.05; HM II: 28.0 ng/mL vs. 738.8 ng/mL, P < 0.001) significantly increased from baseline until the end of the experiments (360 min). After 360 min, TAT and PMN values were significantly higher in the HM II group compared with the values in the CM adult group. The values of SC5b-9 increased from baseline to 360 min in the CM group (CM: 141.8 ng/mL vs. 967.9 ng/mL, P < 0.05) and the HM II group. However, the increase within the HM II group (97.3 vs. 2462.0, P = 0.06) and the comparison of the 360-min values between CM group and HM II group did not reach significance (P = 0.18). The activation of complement, coagulation, and inflammation system showed a time-dependent manner in both devices. The centrifugal CM device showed significantly lower activation of coagulation and inflammation than that of the HM II axial flow pump. Both HM II and CM have demonstrated an acceptable

  19. Critical cavitation coefficient analysis of a space low specific centrifugal pump with micro gravity

    NASA Astrophysics Data System (ADS)

    Liu, J. T.; Li, Y.; Gao, Y.; Hu, Q.; Zhou, C.; Wu, Y. L.

    2016-05-01

    Centrifugal pump was used in the loop as a baselined unit. The flow rate of the pump was very small, while the head was high. This space pump must work stable for a long time (more than a year), so the performance of the pump attracted public attention. The rotational speed of the impeller was limited for stability, so the pump belonged to low specific centrifugal pump. In this paper, a single-phase centrifugal pump, which was designed for single-phase fluid loops in satellites, was modeled for numerical simulation. The hydraulic region of the pump was discretized by structured mesh. Three dimensional (3-D) flow in the pump was studied by the use of computational fluid dynamics. Partially-Averaged Navier- Stokes (PANS) model based on RNG k-ε turbulence model was developed for the simulation of the unsteady flow. Velocity inlet and pressure outlet was used as the boundary conditions. Interface was used between the impeller and the casing, as well as the impeller and inlet pipe. Performances and pressure fluctuation of the pump were investigated. The dominant frequency of the pressure fluctuation is blade passing frequency at the region close to the tongue of the casing, while it is twice of blade passing frequency at the other region.

  20. Flow instability of a centrifugal pump determined using the energy gradient method

    NASA Astrophysics Data System (ADS)

    Li, Yi; Dong, Wenlong; He, Zhaohui; Huang, Yuanmin; Jiang, Xiaojun

    2015-02-01

    The stability of the centrifugal pump has not been well revealed because of the complexity of internal flow. To analyze the flow characteristics of a centrifugal pump operating at low capacity, methods of numerical simulation and experimental research were adopted in this paper. Characteristics of the inner flow were obtained. Standard k-ɛ turbulence models were used to calculate the inner flow of the pump under off-design conditions. The distribution of the energy gradient function K was obtained by three-dimensional numerical simulation at different flow rates. The relative velocity component was acquired from the absolute velocity obtained in particle image velocimetry. By comparing with experimental results, it was found that flow instability occurs at the position of maximum K. The flow stability reduces with an increasing flow rate. The research results provide a theoretical basis for the optimization design of a centrifugal pump.

  1. Performance analysis on solid-liquid mixed flow in a centrifugal pump

    NASA Astrophysics Data System (ADS)

    Ning, C.; Wang, Y.

    2016-05-01

    In order to study the solid-liquid mixed flow hydraulic characteristics of centrifugal pump, the Pro/E software was used for three-dimensional modeling of centrifugal pump chamber. By using the computational fluid dynamics software CFX, the numerical simulation calculation of solid-liquid two-phase flow within whole flow passage of centrifugal pump was conducted. Aim at different particle diameters, the Reynolds-averaged N-S equations with the RNG k-Ɛ turbulence model and SIMPLEC algorithm were used to simulate the two-phase flow respectively on the condition of different volume fraction. The influence of internal flow characteristic on pump performance was analyzed. On the conditions of different particle diameter and different volume fraction, the turbulence kinetic energy and particle concentration are analyzed. It can be found that the erosion velocity ratio on the flow channel wall increases along with the increasing of the volume fraction

  2. Hydrogen test of a small, low specific speed centrifugal pump stage

    NASA Technical Reports Server (NTRS)

    1991-01-01

    A small, low specific speed centrifugal pump stage with a 2 inch tip diameter, .030 inch tip width shrouded impeller and volute collector was tested with liquid hydrogen as the pumped fluid. The hydrodynamic design of the pump stage is summarized and the noncavitating and cavitating performance results are presented. Test speeds were 60 and 80 percent of the 77,000 rpm design speed. Liquid hydrogen test results are compared with data from previous tests of the stage in water.

  3. Response of a radial-bladed centrifugal pump to sinusoidal disturbances for noncavitating flow

    NASA Technical Reports Server (NTRS)

    Anderson, D. A.; Blade, R. J.; Stevans, W.

    1971-01-01

    A radial-bladed centrifugal pump was run in water with sinusoidal fluctuations of pressure and flow rate imposed at the pump inlet. Since the flow was noncavitating, zero gain was assumed in computing pump impedance. The inertive reactance became greater than the resistance at relatively low frequencies. An electric circuit model was developed in order to explain the trends of inertance and resistance with frequency.

  4. Evaluation of platelet damage in two different centrifugal pumps based on measurements of alpha-granule packing proteins.

    PubMed

    Mohara, J; Kawahito, K; Misawa, Y; Fuse, K

    1998-05-01

    Mechanical trauma caused by centrifugal pumps is usually evaluated in terms of hemolysis. However, platelet damage caused by centrifugal pumps has not been studied well. We evaluated platelet damage in 2 different centrifugal pumps, the Medtronic BioMedicus BP-80 and the Terumo Capiox, in vitro and compared the results in terms of hemolysis. To evaluate platelet damage, the rate of increase (RI) for beta-thromboglobulin (beta-TG) and platelet factor-4 (PF-4) were measured by enzyme immunoassay. RI was defined as follows: RI for beta-TG is deltabeta-TG/deltaN and RI for PF-4 is deltaPF-4/deltaN where deltabeta-TG is the increase in beta-TG, deltaPF-4 is the increase in PF-4, and deltaN is the increase of the passing number, which is defined in the following equation: N = Qt/V (t, time; V, priming volume; Q, flow rate). Each pump was tested in a mock circuit for 3 h under a flow rate of 5 L/min and a pressure head of 100 mm Hg using fresh human heparinized blood (n = 5). For comparison, the normalized index of hemolysis (NIH) values were calculated for both pumps. The NIH values did not indicate a significant difference between the Capiox and the BP-80 pumps (Capiox vs. BP-80, 0.0021 +/- 0.0004 vs. 0.0034 +/- 0.0007, NS). However, the RI values for beta-TG and PF-4 in the Capiox were significantly lower than in the BP-80 (beta-TG, 0.198 +/- 0.047 vs. 0.376 +/- 0.049; PF-4, 0.080 +/- 0.014 vs. 0.268 +/- 0.043, p < 0.05). In conclusion, although there was no significant difference between the 2 pumps in terms of hemolysis, the Capiox centrifugal pump induced less platelet damage than the BP-80. The results suggest that measurements of RI for beta-TG and PF-4 are more sensitive parameters than NIH values for evaluating blood cell damage.

  5. A hemodynamic evaluation of the Levitronix Pedivas centrifugal pump and Jostra Hl-20 roller pump under pulsatile and nonpulsatile perfusion in an infant CPB model.

    PubMed

    Ressler, Noel; Rider, Alan R; Kunselman, Allen R; Richardson, J Scott; Dasse, Kurt A; Wang, Shigang; Undar, Akif

    2009-01-01

    The hemodynamic comparison of the Jostra HL-20 and the Levitronix PediVAS blood pumps is the focus this study, where pressure-flow waveforms and hemodynamic energy values are analyzed in the confines of a pediatric cardiopulmonary bypass circuit.The pseudo pediatric patient was perfused with flow rates between 500 and 900 ml/min (100 ml/min increments) under pulsatile and nonpulsatile mode. The Levitronix continuous flow pump utilized a customized controller to engage in pulsatile perfusion with equivalent pulse settings to the Jostra HL-20 roller pump. Hemodynamic measurements and waveforms were recorded at the precannula location, while the mean arterial pressure was maintained at 40 mm Hg for each test. Glycerin water was used as the blood analog circuit perfusate. At each flow rate 24 trials were conducted yielding a total of 120 experiments (n=60 pulsatile and n=60 nonpulsatile).Under nonpulsatile perfusion the Jostra roller pump produced small values for surplus hemodynamic energy (SHE) due to its inherent pulsatility, while the Levitronix produced values of essentially zero for SHE. When switching to pulsatile perfusion, the SHE levels for both the Jostra and Levitronix pump made considerable increases. In comparing the two pumps under pulsatile perfusion, the Levitronix PediVAS produced significantly more surplus and total hemodynamic energy than did the Jostra roller pump each pump flow rate.The study suggests that the Levitronix PediVAS centrifugal pump has the capability of achieving quality pulsatile waveforms and delivering more SHE to the pseudo patient than the Jostra HL-20 roller pump. Further studies are warranted to investigate the Levitronix under bovine blood studies and with various pulsatile settings.

  6. Hemodialysis using a valveless pulsatile blood pump.

    PubMed

    Lee, Kyungsoo; Mun, Cho Hae; Lee, Sa Ram; Min, Byoung Goo; Yoo, Kyu Jae; Park, Yong Woo; Won, Yong Soon

    2008-01-01

    Research on pulsatile blood pumps for extracorporeal life support has been widely performed because of the proven advantageous effects of blood pulsation. However, studies on the use of pulsatile blood pumps for hemodialysis are limited, although available evidence demonstrates that pulsatile blood flow has a positive influence on dialysis outcome. Therefore, the authors designed a new pulsatile pump, which is characterized by minimal-occlusion of blood-containing tubing, no requirement for valves, and no blood flow regurgitation. In-vitro hemolysis tests were conducted using fresh bovine blood, and the normalized index of hemolysis was adopted to compare blood traumas induced by the devised pulsatile pump and a conventional roller pump. In addition, experimental hemodialyses with a canine renal failure model were performed using the devised pump. Normalized index of hemolysis levels obtained was much smaller for the devised pulse pump (45 +/- 21 mg/100 L) than for the roller pump (103 +/- 10 mg/100 L), and no technical problems were encountered during dialysis sessions. Blood and dialysate flow rates were maintained at predetermined values and molecular removal was satisfactory. Postdialysis urea and creatinine reduction ratios were 61.8% +/- 10.6% and 57.4% +/- 9.0%, respectively. Pulsatile flow has usually been generated using pulsatile devices containing valves, but the valves cause concern in terms of the clinical applications of these devices. However, the described pulsatile pump does not require valves, and yet no blood flow regurgitation was observed.

  7. A Method to Determine the Slip Factor of Centrifugal Pumps through Experiment

    NASA Astrophysics Data System (ADS)

    Zhang, Yu-Liang; Zhu, Zu-Chao; Dou, Hua-Shu; Cui, Bao-Ling; Li, Yi; Xiao, Jun-Jian

    2015-04-01

    In this paper, a method to determine the slip factor of centrifugal impellers is proposed based on the experimental result of the external performance of centrifugal pumps. This proposed method is superior to the conventional experimental method, which needs not to measure the flow parameters at impeller outlet. The results show that the present method can be used to obtain the slip factor at offdesign condition in a wide range of flow rate besides at the design point.

  8. Preclinical study of a novel hydrodynamically levitated centrifugal pump for long-term cardiopulmonary support : In vivo performance during percutaneous cardiopulmonary support.

    PubMed

    Tsukiya, Tomonori; Mizuno, Toshihide; Takewa, Yoshiaki; Tatsumi, Eisuke; Taenaka, Yoshiyuki

    2015-12-01

    An extracorporeal centrifugal blood pump with a hydrodynamically levitated impeller was developed for use in a durable extracorporeal membrane oxygenation (ECMO) system. The present study examined the biocompatibility of the blood pump during long-term use by conducting a series of 30-day chronic animal experiments. The ECMO system was used to produce a percutaneous venoarterial bypass between the venae cavae and carotid artery in adult goats. No anticoagulation or antiplatelet therapy was administered during the experiments. Three out of four animals survived for the scheduled 30-day period, and the blood pumps and membrane oxygenators both exhibited sufficient hydrodynamic performance and good antithrombogenicity, while one animal died of massive bleeding from the outflow cannulation site. The animals' plasma free hemoglobin had returned to within the normal range by 1 week after the surgical intervention, and their hemodynamic and biochemistry parameters remained within their normal ranges throughout the experiment. The explanted centrifugal blood pumps did not display any trace of thrombus formation. Based on the biocompatibility demonstrated in this study, the examined centrifugal blood pump, which includes a hydrodynamically levitated impeller, is suitable for use in durable ECMO systems.

  9. Statistical characteristics of suction pressure signals for a centrifugal pump under cavitating conditions

    NASA Astrophysics Data System (ADS)

    Li, Xiaojun; Yu, Benxu; Ji, Yucheng; Lu, Jiaxin; Yuan, Shouqi

    2017-02-01

    Centrifugal pumps are often used in operating conditions where they can be susceptible to premature failure. The cavitation phenomenon is a common fault in centrifugal pumps and is associated with undesired effects. Among the numerous cavitation detection methods, the measurement of suction pressure fluctuation is one of the most used methods to detect or diagnose the degree of cavitation in a centrifugal pump. In this paper, a closed loop was established to investigate the pump cavitation phenomenon, the statistical parameters for PDF (Probability Density Function), Variance and RMS (Root Mean Square) were used to analyze the relationship between the cavitation performance and the suction pressure signals during the development of cavitation. It is found that the statistical parameters used in this research are able to capture critical cavitation condition and cavitation breakdown condition, whereas difficult for the detection of incipient cavitation in the pump. At part-load conditions, the pressure fluctuations at the impeller inlet show more complexity than the best efficiency point (BEP). Amplitude of PDF values of suction pressure increased steeply when the flow rate dropped to 40 m3/h (the design flow rate was 60 m3/h). One possible reason is that the flow structure in the impeller channel promotes an increase of the cavitation intensity when the flow rate is reduced to a certain degree. This shows that it is necessary to find the relationship between the cavitation instabilities and flow instabilities when centrifugal pumps operate under part-load flow rates.

  10. 2011 IEEE Visualization Contest winner: Visualizing unsteady vortical behavior of a centrifugal pump.

    PubMed

    Otto, Mathias; Kuhn, Alexander; Engelke, Wito; Theisel, Holger

    2012-01-01

    In the 2011 IEEE Visualization Contest, the dataset represented a high-resolution simulation of a centrifugal pump operating below optimal speed. The goal was to find suitable visualization techniques to identify regions of rotating stall that impede the pump's effectiveness. The winning entry split analysis of the pump into three parts based on the pump's functional behavior. It then applied local and integration-based methods to communicate the unsteady flow behavior in different regions of the dataset. This research formed the basis for a comparison of common vortex extractors and more recent methods. In particular, integration-based methods (separation measures, accumulated scalar fields, particle path lines, and advection textures) are well suited to capture the complex time-dependent flow behavior. This video (http://youtu.be/oD7QuabY0oU) shows simulations of unsteady flow in a centrifugal pump.

  11. Experimental Characterization of Centrifugal Pumps as AN Acoustic Source at the Blade-Passing Frequency

    NASA Astrophysics Data System (ADS)

    Rzentkowski, G.; Zbroja, S.

    2000-05-01

    Centrifugal pumps represent the primary source of acoustic energy in industrial piping. For hydraulically similar pumps, the amount of emitted energy may vary significantly between different designs and it is generally not known. The available information, typically presented as a magnitude of pressure pulsations measured at the pump discharge, is not free of resonance effects associated with the piping acoustics and, in some aspects, may be seriously misleading. In this paper, we formulate an experimental method to examine the pump acoustic characteristics at the blade-passing frequency. First, we assess the resonance effects in the test-loop. Next, we decompose the measured signal into the components associated with the pump action and with the loop acoustics by means of a simple pump model which is based on a linear superposition of pressure wave transmission and excitation. We apply this technique to examine the acoustics of a single-stage, double-volute centrifugal pump. We estimate the strength of source variables and establish the pump characteristics as an acoustic source. The results indicate that (i) the source variables represent a jump in the acoustic field and are nearly free of resonance effects in the test-loop and that (ii) the pump may act either as a pressure or as a velocity source. Based on this analysis, we postulate that the pressure wave traveling in the direction of pump discharge should be used to define the pump pulsation level for valid comparison between different designs and for acoustic modelling of piping systems.

  12. In vivo assessment of a new method of pulsatile perfusion based on a centrifugal pump.

    PubMed

    Herreros, Jesús; Ubilla, Matías; Berjano, Enrique J; Vila-Nuñez, Juan E; Páramo, José A; Sola, Josu; Mercé, Salvador

    2010-02-01

    The aim of this study was to assess platelet dysfunction and damage to organs after extracorporeal circulation using a pump based on a new method that adds a pulsatile flow to the continuous flow provided by a centrifugal pump. The continuous component of the total flow (2-3 L/min) is created by a Bio-Pump centrifugal pump, while the pulsatile component is created by the pulsating of an inner membrane pneumatically controlled by an intra-aortic counterpulsation balloon console (systolic volume of 37.5 mL in an asynchronous way with a frequency of 60 bpm). Six pigs were subjected to a partial cardiopulmonary bypass lasting 180 min and were sacrificed 60 min after extracorporeal circulation was suspended. The hematological study included the measurement of hematocrit, hemoglobin, leukocytes, and platelet function. The new pump did not significantly alter either platelet count or platelet function. In contrast, hematocrit and hemoglobin were significantly reduced during extracorporeal circulation (approximately 5% P = 0.011, and 2 g/dL P = 0.01, respectively). The leukocyte count during extracorporeal circulation showed a tendency to decrease, but this was not significant. In general, the short-term use of the new pump (4 h) did not cause any serious morphological damage to the heart, lung, kidney, or liver. The results suggest that the hemodynamic performance of the new pump is similar to a conventional centrifugal pump and could therefore be appropriate for use in extracorporeal circulation.

  13. Numerical simulation of flow in centrifugal pump under cavitation and sediment condition

    NASA Astrophysics Data System (ADS)

    Guo, P. C.; Lu, J. L.; Zheng, X. B.; Zhao, Q.; Luo, X. Q.

    2012-11-01

    The sediment concentration is very high in many rivers in the world, especially in China. The pumps that designed for the clear water are usually seriously abraded. The probability of pump cavitation is greatly enhanced due to the existence of sand. Under the joint action and mutual promotion of sand erosion and cavitation, serious abrasion could occurred, and the hydraulic performance of the pump may be greatly descended, meanwhile the safety and stability of the whole pump are greatly threatened. Therefore, it is significant to investigate the cavitation characteristic of pump under sediment flow condition. In this paper, the flow in a single stage centrifugal pump under cleat water and sediment flow conditions was numerically simulated. The cavitation performance under clear water was firstly analyzed. Then, The pressure, velocity and solid particle distribution in centrifugal pump under different particle diameter and different particle concentration was investigated by using the two-fluid model; The area and extent of erosion was illustrated by using the particle track model. Finally, the influence of mixed sand on centrifugal pump performance was investigated.

  14. Cavitation optimization for a centrifugal pump impeller by using orthogonal design of experiment

    NASA Astrophysics Data System (ADS)

    Pei, Ji; Yin, Tingyun; Yuan, Shouqi; Wang, Wenjie; Wang, Jiabin

    2017-01-01

    Cavitation is one of the most important performance of centrifugal pumps. However, the current optimization works of centrifugal pump are mostly focusing on hydraulic efficiency only, which may result in poor cavitation performance. Therefore, it is necessary to find an appropriate solution to improve cavitation performance with acceptable efficiency. In this paper, to improve the cavitation performance of a centrifugal pump with a vaned diffuser, the influence of impeller geometric parameters on the cavitation of the pump is investigated using the orthogonal design of experiment (DOE) based on computational fluid dynamics. The impeller inlet diameter D 1, inlet incidence angle Δ β, and blade wrap angle φ are selected as the main impeller geometric parameters and the orthogonal experiment of L9(3*3) is performed. Three-dimensional steady simulations for cavitation are conducted by using constant gas mass fraction model with second-order upwind, and the predicated cavitation performance is validated by laboratory experiment. The optimization results are obtained by the range analysis method to improve cavitation performance without obvious decreasing the efficiency of the centrifugal pump. The internal flow of the pump is analyzed in order to identify the flow behavior that can affect cavitation performance. The results show that D 1 has the greatest influence on the pump cavitation and the final optimized impeller provides better flow distribution at blade leading edge. The final optimized impeller accomplishes better cavitation and hydraulic performance and the NPSHR decreases by 0.63m compared with the original one. The presented work supplies a feasible route in engineering practice to optimize a centrifugal pump impeller for better cavitation performance.

  15. In Vitro Testing of a Novel Blood Pump Designed for Temporary Extracorporeal Support

    PubMed Central

    Spurlock, DJ; Ranney, DN; Fracz, E; Mazur, DE; Bartlett, RH; Haft, JW

    2012-01-01

    Extracorporeal blood pumps are used as temporary ventricular assist devices or for extracorporeal membrane oxygenation. The ideal pump would be intrinsically self-regulating, carry no risk of cavitation or excessive inlet suction, be afterload insensitive, and valveless thus reducing thrombogenicity. Currently used technology, including roller, centrifugal, and pneumatic pulsatile pumps, does not meet these requirements. We studied a non-occlusive peristaltic pump (M-Pump) in two mock circulatory loops, and compared the performance to a frequently used centrifugal pump and a modified prototype of the M-Pump (the BioVAD). The simple resistance loop consisted of the investigated pump, a fixed height reservoir at 150 mmHg, and a variable inflow reservoir. The pulsatile circulation utilized a mock patient simulator with adjustable resistance elements connected to a pneumatic pulsatile pump. The M-Pump intrinsically regulated flow with changing preload, was afterload insensitive, and did not cavitate, unlike the centrifugal pump. The BioVAD also demonstrated these features, and could augment output with use of vacuum assistance. A non-occlusive peristaltic pump may be superior for short term extracorporeal circulatory assist by mitigating risks of excessive inlet suction, afterload sensitivity, and thrombosis. PMID:22236624

  16. In vitro testing of a novel blood pump designed for temporary extracorporeal support.

    PubMed

    Spurlock, David J; Ranney, David N; Fracz, Emilia M; Mazur, Daniel E; Bartlet, R H; Haft, Jonathan W

    2012-01-01

    Extracorporeal blood pumps are used as temporary ventricular assist devices or for extracorporeal membrane oxygenation. The ideal pump would be intrinsically self-regulating, carry no risk of cavitation or excessive inlet suction, be afterload insensitive, and valveless thus reducing thrombogenicity. Currently used technology, including roller, centrifugal, and pneumatic pulsatile pumps, does not meet these requirements. We studied a nonocclusive peristaltic pump (M-Pump) in two mock circulatory loops and compared the performance to a frequently used centrifugal pump and a modified prototype of the M-Pump (the BioVAD). The simple resistance loop consisted of the investigated pump, a fixed height reservoir at 150 mm Hg, and a variable inflow reservoir. The pulsatile circulation used a mock patient simulator with adjustable resistance elements connected to a pneumatic pulsatile pump. The M-Pump intrinsically regulated flow with changing preload, was afterload insensitive, and did not cavitate, unlike the centrifugal pump. The BioVAD also demonstrated these features and could augment output with the use of vacuum assistance. A nonocclusive peristaltic pump may be superior for short-term extracorporeal circulatory assist by mitigating risks of excessive inlet suction, afterload sensitivity, and thrombosis.

  17. A concept for improving efficiency of multistage centrifugal pumps

    NASA Technical Reports Server (NTRS)

    Gardy, H. F.

    1970-01-01

    Multichannel impeller consists of successive stage impellers arranged concentrically without clearances between them. Reduction in friction is predicted to increase pump efficiency by 5 to 10 percent.

  18. Cavitation performance and flow characteristic in a centrifugal pump with inlet guide vanes

    NASA Astrophysics Data System (ADS)

    Tan, L.; Zha, L.; Cao, S. L.; Wang, Y. C.; Gui, S. B.

    2015-01-01

    The influence of prewhirl regulation by inlet guide vanes (IGVs) on cavitation performance and flow characteristic in a centrifugal pump is investigated. At the impeller inlet, the streamlines are regulated by the IGVs, and the axial velocity distribution is also influenced by the IGVs. Due to the total pressure loss on the IGVs, the cavitation performance of the centrifugal pump degrades. The cavitation area in impeller with IGVs is larger than one without IGVs. The specify values of total pressure loss between the suction pipe inlet and impeller inlet for three cavitation conditions show that the IGVs will generate additional pressure loss, which is related to the IGVs angles and cavitation conditions.

  19. Application of energy gradient theory in flow instability in a centrifugal pump

    NASA Astrophysics Data System (ADS)

    Dou, H. S.; Jiang, W.

    2013-12-01

    The flow instability in a centrifugal pump is studied using the energy gradient theory. Since the Re is high, the base flow is assumed to be turbulent. The distribution of the energy gradient function K at various flow rates is obtained from numerical simulations. According to the energy gradient method, the area with larger value of K is the place to cause instability and to be of high turbulence intensity. The results show that instability is easier to be excited in the area of impeller outlet and volute tongue. In order to improve the stability of centrifugal pumps working under low flow rate condition, carefulness must be taken in these two key areas.

  20. Numerical simulation and analysis of cavitation flows in a double suction centrifugal pump

    NASA Astrophysics Data System (ADS)

    Meng, G.; Tan, L.; Cao, S. L.; Jian, W.; Liu, W. W.; Jiang, D. J.

    2015-01-01

    Cavitation is an unsteady phenomenon, which is nearly inevitable in pumps. It would degrade the pump performance, generate vibrations and noises, and even erode pump flow passage components. The double suction centrifugal pump at design flow rate and large flow rate is numerically simulated using the k-ω turbulence model and the mass transport cavitation model. As a result, the calculated variation of pump head with pump inlet pressure agreed well with the experimental data. The results demonstrate that the numerical model and method can accurately predict the cavitation flows in a double suction centrifugal pump. The cavitation characteristics are analysed in great details. In addition, based on the calculation results, the reason that the plunge of pump head curve is revealed. It is found that the steep fall of pump head happens when the cavity reaches the blade to blade throat and the micro-vortex group appears at the back of the blade suction side. At the same time, this practice can provide guidance for the optimal design of double suction pumps.

  1. Research on the noise induced by cavitation under the asymmetric cavitation condition in a centrifugal pump

    NASA Astrophysics Data System (ADS)

    Lu, J. X.; Yuan, S. Q.; Yuan, J. P.; Ren, X. D.; Pei, J.; Si, Q. R.

    2015-12-01

    An experimental investigation has been carried out to research the noise induced by cavitation under the asymmetric cavitation (AC) condition in a centrifugal pump. The acoustic pressure signals at the pump inlet and outlet were measured respectively during the development of cavitation in a closed hydraulic test rig. It could be found that both the pump inlet and outlet acoustic pressures changed obviously with the development of cavitation. The time domain and the power spectrum density of the pump inlet and outlet acoustic pressure pulsations were analyzed. The broadband pulses of the acoustic pressure pulsations were found and the reasons for the phenomenon were given.

  2. Experimental testing of centrifugal pump: small and medium sized enterprise product

    NASA Astrophysics Data System (ADS)

    Ismail, R.; Paddiyatu, F.; Khafidh, M.; Nugroho, S.; Sugiyanto, S.; Jamari, J.

    2014-06-01

    This paper reports the experimental testing for centrifugal pump for fisherman ship, manufactured by small and medium sized enterprises in Central Java Province, Indonesia. The research covers material analysis, component observation, endurance and vibration test. Six centrifugal pumps are tested and three main pump components are discussed: shaft, bearings and seals. The results show that the material of the shaft is predicted to support and transmit the load from the engine to impeller. The problem found in the tolerance and geometry accuracy of the shaft which causes difficulties during assembling process, excessive wear and leakage during testing. From the endurance and vibration test, the ball bearings fail and lock the shaft due to the fatigue on the rolling elements and raceways. The oil seal and water seal also fail in maintaining the oil and water in the chamber and induce the unlubricated system for the ball bearings. Some suggestions are delivered to improve the product quality of the centrifugal pump. A good quality of the centrifugal pump for fishermen ship and long life span is expected to be produced by local SMEs to win the free trade competition in the Indonesian market.

  3. Platelet function during cardiopulmonary bypass using multiple electrode aggregometry: comparison of centrifugal and roller pumps.

    PubMed

    Kehara, Hiromu; Takano, Tamaki; Ohashi, Noburo; Terasaki, Takamitsu; Amano, Jun

    2014-11-01

    Blood trauma may be lower with centrifugal pumps (CPs) than with roller pumps (RPs) during cardiopulmonary bypass (CPB), because, unlike RPs, CPs do not compress the tubing, and shear stress is considered lower in CPs than in RPs. However, relative platelet function remains unclear. Using multiple electrode aggregometry (MEA), we compared platelet function with CP and RP. Ten swine underwent CPB for 3 h, with five weaned off using CP and five using RP. Platelet function was measured using MEA, as were hemoglobin concentration and platelet count, before sternotomy, after heparin infusion, 30 min and 3 h after starting CPB, after protamine infusion, and 60 min after stopping CPB. Platelet activation was initiated with adenosine diphosphate (ADP), arachidonic acid (AA), and thrombin receptor-activating protein 6 (TRAP). Fibrinogen, platelet factor 4 (PF4), and β-thromboglobin (β-TG) concentrations were measured before sternotomy and 60 min after stopping CPB. In the CP group and using ADP, aggregation was significantly reduced 30 min (P = 0.019) and 3 h (P = 0.027) after starting CPB, recovering to baseline 60 min after CPB was stopped. In the RP group, aggregation was significantly decreased 30 min (P = 0.007) and 3 h (P = 0.003) after starting CPB and after protamine administration (P = 0.028). With AA, aggregation significantly decreased 30 min after starting CPB in both the CP (P = 0.012) and RP (P = 0.016) groups, slightly increasing 3 h after starting CPB and after protamine infusion, and recovering to baseline 60 min after CPB cessation. With TRAP, aggregation in the CP and RP groups decreased 30 min after starting the pump, although changes were not significant; aggregation gradually recovered after 3 h and returned to baseline 60 min after the pumps were stopped. There were no significant differences at all sampling points of MEA. In both groups, fibrinogen, PF4, and β-TG concentrations were similar 60 min after pump cessation and before sternotomy

  4. Method of investigation of vibroacoustic characteristics of centrifugal pumps

    NASA Technical Reports Server (NTRS)

    Pokrovskiy, B. V.; Rubinov, V. Y.; Yurgin, A. M.

    1973-01-01

    A method for acoustical diagnostics of pumps is described which consists of taking sonograms of the pump, by means of an audio spectrograph. In distinction from usual analyzers, the spectrograph makes it possible to obtain a three-dimensional image of the signal being analyzed, in which its frequency-amplitude characteristics developed over time are depicted with a resolving power of 0.004 sec. As an example, a sonogram of an electrically driven pump, in the 40-4000 Hz frequency range, is presented. The amplitude ratios are determined on the sonogram by the contrast of individual contours, with an accuracy of 6 db.

  5. Numerical identification of blade exit angle effect on the performance for a multistage centrifugal pump impeller

    NASA Astrophysics Data System (ADS)

    Babayigit, Osman; Kocaaslan, Osman; Hilmi Aksoy, Muharrem; Melih Guleren, Kursad; Ozgoren, Muammer

    2015-05-01

    Nowadays, single and multistage centrifugal pumps are widely used in industrial and mining enterprises. One of the most important components of a centrifugal pump is the impeller. The performance characteristics are related to the pump comprising the head and the overall efficiency rely a great deal on the impeller geometry. In this work, effects of blade exit angle change on hydraulic efficiency of a multi stage pump impeller are investigated via Ansys-Fluent computational fluid dynamics software for constant width impeller entrance and exit gates, blade numbers and blade thickness. Firstly, the flow volume of a centrifugal pump impeller is generated and then mesh structure is formed for the full impeller flow volume. Secondly, rotational periodic flow model are adopted in order to examine the effect of periodic flow assumption on the performance predictions. Corresponding to the available experimental data, inlet mass flow rate, outlet static pressure and rotation of impeller are taken as 0.02m3s-1, 450 kPa and 2950 rpm, respectively for the water fluid. No slip boundary condition is exposed to all solid of surface in the flow volume. The continuity and Navier-Stokes equations with the k-ɛ turbulence model and the standard wall functions are used. During the study, numerical analyses are conducted for the blade exit angle values of 18°, 20°, 25°, 30° and 35°. In consequence of the performed analyses, it is determined that hydraulic efficiency of the pump impeller value is changed between 81.0-84.6%. The most convenient blade exit angle that yields 84.6% hydraulic efficiency at is 18°. The obtained results show that the blade exit angle range has an impact on the centrifugal pump performance describing the pump head and the hydraulic efficiency.

  6. Transformation of vibration signals in rotary blood pumps: the diagnostic potential of pump failure.

    PubMed

    Kawahito, Koji

    2013-09-01

    Although non-destructive and continuous monitoring is indispensable for long-term circulatory support with rotary blood pumps, a practical monitoring system has not yet been developed. The objective of this study was to investigate the possibility of detecting pump failure caused by thrombus formation through the monitoring of vibration signals. The data acquisition equipment included vibration pickups, a charge amplifier, vibration analysis systems, and exclusive hardware. A pivot-bearing centrifugal pump with a mock circuit was investigated for vibration analysis. To simulate the four common areas of thrombus formation, we used a piece of silicon attached to each of the following four locations: the total area of the bottom of the impeller, an eccentric shape on the bottom of the impeller, a circular shape around the shaft top, and an eccentric shape on the top of the impeller. Vibration signals were picked up, and the power spectrum density analysis was performed at pump rotational speeds of 2100, 2400, and 3000 rpm. In this study, pump failure could be detected, and the types of imitation thrombi could be determined. We conclude that vibration detection with a computerized analysis system is a potentially valuable diagnostic tool for long-term circulatory support with rotary blood pumps.

  7. Numerical analysis of the flow field in the pump chamber of a centrifugal pump with back blades

    NASA Astrophysics Data System (ADS)

    Cao, L.; Wang, Z. W.; Y Luo, Y.; Liu, M.

    2013-12-01

    Black blade is frequently used as a non-contact seal structure in centrifugal pumps transporting solid-liquid two-phase flow. However, it will disturb the flow in the pump and affect the pump performance. Numerical simulation for 3D turbulence in whole flow passage of a centrifugal pump with back blades was carried out based on RANS method, with SST k-ω turbulence model and SIMPLEC algorithm. Calculation for a similar pump without back blades was also carried out as a comparison. Boundary condition was improved due to the existence of back blade. The influence of back blades on the flow field was analysed qualitatively for three typical conditions. Meanwhile the leakage rate was calculated for several conditions and the effect of back blades was discussed. According to the results, compared with the condition without back blades, it could be seen that back blade apparently changed the flow state in the front chamber, improved near the front shroud and worsened near the pump cover. Velocity was increased and more fluid, which flowed into the front chamber from the pump cover side, flowed back to the spiral casing from the impeller shroud side. With the increase of discharge, the absolute value of leakage rate first went up and then dropped, as a consequence of the combination of two factors, discharge and differential pressure between the impeller outlet and inlet. The seal effect of back blades is most obvious under small discharge condition, and the leakage loss diminished as discharge increased.

  8. Experimental and numerical investigation of centrifugal pumps with asymmetric inflow conditions

    NASA Astrophysics Data System (ADS)

    Mittag, Sten; Gabi, Martin

    2015-11-01

    Most of the times pumps operate off best point states. Reasons are changes of operating conditions, modifications, pollution and wearout or erosion. As consequences non-rotational symmetric flows, transient operational conditions, increased risk of cavitation, decrease of efficiency and unpredictable wearout can appear. Especially construction components of centrifugal pumps, in particular intake elbows, contribute to this matter. Intake elbows causes additional losses and secondary flows, hence non-rotational velocity distributions as intake profile to the centrifugal pump. As a result the impeller vanes experience permanent changes of the intake flow angle and with it transient flow conditions in the blade channels. This paper presents the first results of a project, experimentally and numerically investigating the consequences of non-rotational inflow to leading edge flow conditions of a centrifugal pump. Therefore two pumpintake- elbow systems are compared, by only altering the intake elbow geometry: a common single bended 90° elbow and a numerically optimized elbow (improved regarding rotational symmetric inflow conditions and friction coefficient). The experiments are carried out, using time resolved stereoscopic PIV on a full acrylic pump with refractions index matched (RIM) working fluid. This allows transient investigations of the flow field simultaneously for all blade leading edges. Additional CFD results are validated and used to further support the investigation i.e. for comparing an analog pump system with ideal inflow conditions.

  9. CENTRIFUGE APPARATUS

    DOEpatents

    Skarstrom, C.; Urey, H.C.; Cohen, K.

    1960-08-01

    A high-speed centrifuge for the separation of gaseous isotopes is designed comprising a centrifugal pump mounted on the outlet of a centrifuge bowl and arranged to pump the heavy and light fractions out of the centrifuge bowl in two separate streams.

  10. Numerical investigation of nonlinear vibration for rotor-seal system of centrifugal pump

    NASA Astrophysics Data System (ADS)

    Zhou, W. J.; Yang, Y. C.; Xing, G. K.; Wang, L. Q.

    2013-12-01

    The exciting force in the seal is an important factor for the stability of a multiple stage centrifugal pump. With the speed increasing, the rotor system of multiple stage centrifugal pump presents some nonlinear characters. In order to provide supports for the research of nonlinear characters of multiple stage centrifugal pump, a rotor-seal system model of centrifugal pump is presented and the Muszynska nonlinear seal model is used to express the seal exciting force with multiple parameters in the paper. The fourth-order Runge-Kutta method is also used to determine the vibration response at the impeller place and obtain bifurcation diagram, axis orbit, phase diagram as well as Poincaré Map. The bifurcation results show that the rotor-seal system would be stable under a lower speed and change to be unstable as the rotor speed increases. Various multi-periodic motions and quasi-periodic motions are found showing the complicated motions in the rotor-seal system under nonlinear seal forces.

  11. Numerical simulation and analysis of solid-liquid two-phase flow in centrifugal pump

    NASA Astrophysics Data System (ADS)

    Zhang, Yuliang; Li, Yi; Cui, Baoling; Zhu, Zuchao; Dou, Huashu

    2013-01-01

    The flow with solid-liquid two-phase media inside centrifugal pumps is very complicated and the relevant method for the hydraulic design is still immature so far. There exist two main problems in the operation of the two-phase flow pumps, i.e., low overall efficiency and severe abrasion. In this study, the three-dimensional, steady, incompressible, and turbulent solid-liquid two-phase flows in a low-specific-speed centrifugal pump are numerically simulated and analyzed by using a computational fluid dynamics (CFD) code based on the mixture model of the two-phase flow and the RNG k- ɛ two-equation turbulence model, in which the influences of rotation and curvature are fully taken into account. The coupling between impeller and volute is implemented by means of the frozen rotor method. The simulation results predicted indicate that the solid phase properties in two-phase flow, especially the concentration, the particle diameter and the density, have strong effects on the hydraulic performance of the pump. Both the pump head and the efficiency are reduced with increasing particle diameter or concentration. However, the effect of particle density on the performance is relatively minor. An obvious jet-wake flow structure is presented near the volute tongue and becomes more remarkable with increasing solid phase concentration. The suction side of the blade is subject to much more severe abrasion than the pressure side. The obtained results preliminarily reveal the characteristics of solid-liquid two-phase flow in the centrifugal pump, and are helpful for improvement and empirical correction in the hydraulic design of centrifugal pumps.

  12. A centrifugal pump driven tidal flow extracorporeal membrane oxygenation system tested with neonatal mock circulation.

    PubMed

    Trittenwein, G; Kölbl, R; Trittenwein, H; Golej, J; Burda, G; Hermon, M; Pollak, A

    1999-06-01

    In 1993, Chevalier published his experiences with tidal flow venovenous extracorporeal membrane oxygenation (ECMO) featuring a single lumen cannula, non-occlusive roller pump, and alternating clamps. Using a neonatal mock circulation (NMC), which enables different hemodynamic states for neonatal ECMO research, the tested hypothesis was that it is possible to create a centrifugal pump driven tidal flow neonatal venovenous ECMO system. Additionally, the resulting hemodynamic effects in a condition of circulatory impairment were investigated. The ECMO circuit tested was assembled using a pediatric centrifugal pump head, a distensible reservoir, and a rotary clamp separating drainage from the injection phase. Using the NMC, end tidal volumes, mock circulation flow, and arterial and venous pressures were measured at different pump speeds after the drainage and injection phases. Effective venovenous ECMO flow (evvEF) was calculated. Mock circulation baseline values (ECMO clamped) were compared to values during tidal flow ECMO. At 3,000 rpm, a centrifugal pump speed of 75 ml/kg/min evvEF was reached, and it increased with higher pump speeds. At this point, the end tidal mock circulation flow (representing cardiac output) after drainage differed significantly from that during the injection phase (p < 0.01) but not from the baseline value. The end tidal arterial and venous pressures after the drainage phase were found to be significantly decreased compared to the baselines (p < 0.01). In conclusion, a centrifugal pump driven tidal flow venovenous ECMO system can be created enabling sufficient tidal volumes. Tested in the described NMC simulating posthypoxic circulatory impairment, significant hemodynamic effects could be demonstrated. Animal experiments for confirmation are necessary.

  13. Influence of the empirical coefficients of cavitation model on predicting cavitating flow in the centrifugal pump

    NASA Astrophysics Data System (ADS)

    Liu, Hou-lin; Wang, Jian; Wang, Yong; Zhang, Hua; Huang, Haoqin

    2014-03-01

    The phenomenon of cavitation is an unsteady flow, which is nearly inevitable in pump. It would degrade the pump performance, produce vibration and noise and even damage the pump. Hence, to improve accuracy of the nu¬merical prediction of the pump cavitation performance is much desirable. In the present work, a homogenous model, the Zwart-Gerber-Belamri cavitation model, is considered to investigate the influence of the empirical coefficients on predicting the pump cavitation performance, concerning a centrifugal pump. Three coefficients are analyzed, namely the nucleation site radius, evaporation and condensation coefficients. Also, the experiments are carried out to validate the numerical simulations. The results indicate that, to get a precise prediction, the approaches of declining the initial bubble radius, the condensation coefficient or increasing the evaporation coefficient are all feasible, especially for de¬clining the condensation coefficient, which is the most effective way.

  14. CENTRIFUGE

    DOEpatents

    Rushing, F.C.

    1960-09-01

    A vibration damping mechanism for damping vibration forces occurring during the operation of a centrifuge is described. The vibration damping mechanism comprises a plurality of nested spaced cylindrical elements surrounding the rotating shaft of the centrifuge. Some of the elements are held substantially stationary while the others are held with respect to a pair of hearings spaced along the rotating shaft. A fluid is retained about the cylindrical elements.

  15. A study on energy saving rate for variable speed condition of multistage centrifugal pump

    NASA Astrophysics Data System (ADS)

    Suh, Sang-Ho; Rakibuzzaman; Kim, Kyung-Wuk; Kim, Hyoung-Ho; Yoon, In Sik; Cho, Min-Tae

    2015-11-01

    Centrifugal pumps are being widely used in many industrial and commercial applications. Many of these pumps are being operated at constant speed but could provide energy savings through adjustable speed operations. The purpose of this study was to get the energy saving rates of the multistage centrifugal pump with variable speed conditions. For this investigation an experimental set up of variable flow and pressure system was made to get energy saving rates and numerical analyses are applied to validate the pump performance. The energy saving and therefore the cost saving depends on the specific duty cycle of which the machine operates. Duty cycle is the proportion of time during which a component, device and system is operated. The duty cycle segmented into different flow rates and weighting the average value for each segment by the interval time. The system was operated at 50% or less of the pump capacity. The input power of the system was carried out by pump characteristics curve of each operating point. The energy consumption was done by the product of specific duty cycle and the input power of the system for constant speed and variable speed drive operation. The total energy consumed for constant speed drive pump was 75,770 kW.hr and for variable speed drive pump was 31,700 kW.hr. The total energy saving of the system was 44,070 kW.hr or 58.16% annually. So, this paper suggests a method of implementing an energy saving on variable-flow and pressure system of the multistage centrifugal pump.

  16. Influence of hydrophibization of impellers of centrifugal pumps on their operating characteristics

    NASA Astrophysics Data System (ADS)

    Volkov, A. V.; Parygin, A. G.; Naumov, A. V.; Vikhlyantsev, A. A.; Šoukal, J.; Sedlář, M.; Komárek, M.

    2016-12-01

    This work presents experimental estimation results of changing of basic operation characteristics of a group of centrifugal pumps covering a range of values of dimensionless power-speed coefficient n s from 33 to 330 after hydrophobization of their impellers' surfaces. Hydrophobization of functional surfaces of impellers in all experiments was performed by formation of structures of organic covers by technology of MPEI NRU, which provides increasing of limiting wetting angle of surfaces to 120° and greater. Results of experimental researches of the influence of hydrophobization of impeller surfaces for high-speed pump ( n s = 330) on its characteristics is presented for the first time. Positive effect of applying hydrophobization technology to impeller surfaces in all the considered range of power-speed coefficient was generalized and estimated. It was shown that hydrophobization of impeller surfaces of centrifugal pumps provides increment to their efficiency factors within an acceptable operation range from 0.5 to 7.5%. Empiric function defining dependencies of efficiency factor increment of pump on relative supply and power-speed coefficient are suggested. Possibilities and estimation of extending acceptable operation range of a pump depending on powerspeed coefficient as a result of impeller surface hydrophobization are shown. Experimental data of comparative cavitation tests of high-speed pumps before and after hydrophobization of their impeller surfaces are generalized for the first time for considered range of power-speed coefficient values. The influence of power-speed coefficient on changing of critical net pump suction head (critical positive suction pressure) is shown. Based on existing knowledge on pumps, an attempt to validate experimentally obtained lows of changing of power and anticavitation features of centrifugal pumps after hydrophobization of their impeller surfaces is made.

  17. A survey of instabilities within centrifugal pumps and concepts for improving the flow range of pumps in rocket engines

    NASA Astrophysics Data System (ADS)

    Veres, Joseph P.

    1992-02-01

    Design features and concepts that have primary influence on the stable operating flow range of propellant-feed centrifugal turbopumps in a rocket engine are discussed. One of the throttling limitations of a pump-fed rocket engine is the stable operating range of the pump. Several varieties of pump hydraulic instabilities are mentioned. Some pump design criteria are summarized and a qualitative correlation of key parameters to pump stall and surge are referenced. Some of the design criteria were taken from the literature on high pressure ratio centrifugal compressors. Therefore, these have yet to be validated for extending the stable operating flow range of high-head pumps. Casing treatment devices, dynamic fluid-damping plenums, backflow-stabilizing vanes, and flow-reinjection techniques are summarized. A planned program was undertaken at LeRC to validate these concepts. Technologies developed by this program will be available for the design of turbopumps for advanced space rocket engines for use by NASA in future space missions where throttling is essential.

  18. A survey of instabilities within centrifugal pumps and concepts for improving the flow range of pumps in rocket engines

    NASA Technical Reports Server (NTRS)

    Veres, Joseph P.

    1992-01-01

    Design features and concepts that have primary influence on the stable operating flow range of propellant-feed centrifugal turbopumps in a rocket engine are discussed. One of the throttling limitations of a pump-fed rocket engine is the stable operating range of the pump. Several varieties of pump hydraulic instabilities are mentioned. Some pump design criteria are summarized and a qualitative correlation of key parameters to pump stall and surge are referenced. Some of the design criteria were taken from the literature on high pressure ratio centrifugal compressors. Therefore, these have yet to be validated for extending the stable operating flow range of high-head pumps. Casing treatment devices, dynamic fluid-damping plenums, backflow-stabilizing vanes and flow-reinjection techniques are summarized. A planned program was undertaken at LeRC to validate these concepts. Technologies developed by this program will be available for the design of turbopumps for advanced space rocket engines for use by NASA in future space missions where throttling is essential.

  19. Performance of a small centrifugal pump in He I and He II

    NASA Technical Reports Server (NTRS)

    Ludtke, P. R.; Daney, D. E.; Steward, W. G.

    1988-01-01

    The performance characteristics of a small centrifugal pump in He I and He II are determined over the temperature range of 1.6 to 4.2 K. The single-stage pump is powered by a close-coupled cryogenic induction motor. In the absence of cavitation, pump performance (head and capacity) was found to be identical for He I and He II. Developed heads up to 16 m and capacities of up to 900 liters/hr are obtained at 7000 rpm. A three-blade screw inducer was shown to require much less suction head than a six-blade propeller inducer.

  20. Performance of a small centrifugal pump in He I and He II

    NASA Astrophysics Data System (ADS)

    Ludtke, P. R.; Daney, D. E.; Steward, W. G.

    The performance characteristics of a small centrifugal pump in He I and He II are determined over the temperature range of 1.6 to 4.2 K. The single-stage pump is powered by a close-coupled cryogenic induction motor. In the absence of cavitation, pump performance (head and capacity) was found to be identical for He I and He II. Developed heads up to 16 m and capacities of up to 900 liters/hr are obtained at 7000 rpm. A three-blade screw inducer was shown to require much less suction head than a six-blade propeller inducer.

  1. Internal flow numerical simulation of double-suction centrifugal pump using DES model

    NASA Astrophysics Data System (ADS)

    Zhou, P. J.; Wang, F. J.; Yang, M.

    2012-11-01

    It is a challenging task for the flow simulation for a double-suction centrifugal pump, because the wall effects are strong in this type of pumps. Detached-eddy simulation (DES), referred as a hybrid RANS-LES approach, has emerged recently as a potential compromise between RANS based turbulence models and Large Eddy Simulation. In this approach, the unsteady RANS model is employed in the boundary layer, while the LES treatment is applied to the separated region. In this paper, S-A DES method and SST k-ω DES method are applied to the numerical simulation for the 3D flow in whole passage of a double-suction centrifugal pump. The unsteady flow field including velocity and pressure distributions is obtained. The head and efficiency of the pump are predicted and compared with experimental results. According to the calculated results, S-A DES model is easy to control the partition of the simulation when using near wall grid with 30 < y+<300 control approach. It also has better performance on efficiency and accuracy than SST k - ω DES method. S-A DES method is more suitable for solving the unsteady flow in double-suction centrifugal pump. S-A DES method can capture more flow phenomenon than SST k - ω DES method. In addition, it can accurately predict the power performance under different flow conditions, and can reflect pressure fluctuation characteristics.

  2. Investigation of the Flow Field and Performances of a Centrifugal Pump at Part Load

    NASA Astrophysics Data System (ADS)

    Prunières, R.; Inoue, Y.; Nagahara, T.

    2016-11-01

    Centrifugal pump performance curve instability, characterized by a local dent at part load, can be the consequence of flow instabilities in rotating or stationary parts. Such flow instabilities often result in abnormal operating conditions which can damage both the pump and the system. In order for the pump to have reliable operation over a wide flow rate range, it is necessary to achieve a design free of instability. The present paper focuses on performance curve instability of a centrifugal pump of mid specific speed (ωs = 0.65) for which instability was observed at part load during tests. The geometry used for this research consist of the first stage of a multi-stage centrifugal pump and is composed of a suction bend, a closed-type impeller, a vaned diffuser and return guide vanes. In order to analyse the instability phenomenon, PIV and CFD analysis were performed. Both methods qualitatively agree relatively well. It appears that the main difference before and after head drop is an increase of reverse flow rate at the diffuser passage inlet on the hub side. This reverse flow decreases the flow passing area at the diffuser passage inlet, disallowing effective flow deceleration and impairing static pressure recovery.

  3. Blade design loads on the flow exciting force in centrifugal pump

    NASA Astrophysics Data System (ADS)

    Xu, Y.; Yang, A. L.; Langand, D. P.; Dai, R.

    2012-11-01

    The three-dimensional viscous flow field of two centrifugal pumps, which have the same volute, design head, design flow rate and rotational speed but the blade design load, are analyzed based on large eddy simulation. The comparisons are implemented including the hydraulic efficiencies, flow field characteristics, pressure pulsations and unsteady forces applied on the impellers to investigate the effect of the design blade load on hydraulic performance and flow exciting force. The numerical results show that the efficiency of the pump, the impeller blade of which has larger design load, is improved by 1.1%~2.9% compared to the centrifugal pump with lower blade design load. The pressure fluctuation of the pump with high design load is more remarkable. Its maximum amplitude of coefficient of static pressure is higher by 43% than the latter. At the same time the amplitude of unsteady radial force is increased by 11.6% in the time domain. The results also imply that the blade design load is an important factor on the excitation force in centrifugal pumps.

  4. Unsteady diffuser vane pressure and impeller wake measurements in a centrifugal pump

    NASA Technical Reports Server (NTRS)

    Arndt, N.; Acosta, A. J.; Brennen, C. E.; Caughey, T. K.

    1987-01-01

    Unsteady surface pressure measurements on a vaned diffuser of a centrifugal pump, and wake measurements of the flow exiting a centrifugal impeller into a vaneless diffuser are presented. Frequency spectra and ensemble averages are given for the unsteady measurements. Two different impellers were used, the pump impeller of the HPOTP (High Pressure Oxygen Turbopump) of the SSME (Space Shuttle Main Engine) and a two-dimensional impeller. The magnitude of the unsteady total pressure measured in the stationary frame at the impeller exit was found to be of the same order of magnitude as the total pressure rise across the pump. The magnitude of the unsteady diffuser vane pressures was observed to be significantly different on suction and pressure side of the vane, attaining its largest value on the suction side the leading edge while decreasing along the vane.

  5. Part-load flow and hydraulic stability of centrifugal pumps

    SciTech Connect

    Guelich, J.F.; Egger, R. )

    1992-03-01

    Unscheduled outages and deratings caused by problems with feed pumps cost utilities an estimated $460 million in replacement power costs 1985. Vibrations and pressure pulsations caused by the flow separation at partload operation are among the leading causes of feed pump failures. To reduce or avoid such failures, the flow mechanisms responsible for hydraulic instabilities must be understood. To increase this understanding was one of the main objectives of the hydraulic investigations carried out under the present research project and described in this report. A large number of parameters influencing the hydraulic performance and the stability of the head capacity characteristics have been investigated and guidelines have been derived for the selection of design parameters for impellers, diffusers, and volutes.

  6. Successful application of horizontal multistage centrifugal pumps in lean amine service

    SciTech Connect

    Lopez, M.; Goodwin, B.

    1998-12-31

    Installation of horizontal multistage centrifugal pumps in lean amine service has proven to be extremely successful and economical at Union Pacific Resources (UPR) East Texas Gas Plant (ETGP) located in Carthage, Texas. In the past, UPR used either vertical can pumps or positive displacement (PD) pumps for amine circulation in their gas treating operations. When the need to replace a PD pump in the No. 4 Amine Plant arose, UPR solicited bids from both traditional pump suppliers. Additionally, UPR solicited a bid from REDA for their Horizontal Pumping System (HPS) based on previous success of this type of pump at ETGP in salt water disposal service. Pump system cost comparisons revealed that REDA`s HPS had a cost savings of approximately 35% over the PD or vertical can pump options. In addition, the installation cost of the REDA pump showed a significant savings versus a vertical can pump. Thus UPR opted to install and evaluate the performance of the HPS in amine service. This was the first installation of a horizontal multistage pump for amine service in UPR`s gas treating plants and was also REDA`s first use of its HPS in this type of application. The first pump was installed in May 1996 and designed to circulate a maximum of 80 gpm. Since installation of the pump in No. 4 Amine Treating Unit, UPR has not experienced any downtime and has realized a significant cost savings on maintenance labor and parts over the previous positive displacement installation. The success of this HPS in amine service has led UPR to invest in five additional HPS pumps for the ETGP in amine service.

  7. Cavitation improvement of double suction centrifugal pump HPP Fuhren

    NASA Astrophysics Data System (ADS)

    Škerlavaj, A.; Titzschkau, M.; Pavlin, R.; Vehar, F.; Mežnar, P.; Lipej, A.

    2012-11-01

    A double suction storage pump has been refurbished because of the strong cavitation which resulted in cavitation damage on blade and consequently in frequent repairs of the impeller. The analyses of the old and the new impeller were done by the computational fluid dynamics (CFD), performing transient simulations with the commercial solver Ansys CFX. In the simulations, the scale-adaptive-simulation with the curvature correction (SAS-CC) turbulence model was used. No model tests were carried out. Additionally, observations with the digital camera were made through the specially designed plexi-glass window, mounted at the lid at the suction side. The predicted pump head at the operating point agrees well with the pump characteristics measurements, performed with the direct thermodynamic method. The extent of the cavitation predicted by CFD is smaller than the observed one because the cloud cavitation was not predicted. The observations of the cavitation extent show that the impeller design is better than the old one, which was also possible to anticipate based on the CFD results.

  8. The valvo-pump. An axial, nonpulsatile blood pump.

    PubMed

    Mitamura, Y; Yozu, R; Tanaka, T; Yamazaki, K

    1991-01-01

    The valvo-pump, an axial, nonpulsatile blood pump implanted at the heart valve position while preserving diseased heart muscle, has several advantages over an artificial heart replacement, including 1) a good anatomic fit to the natural heart, 2) less blood contacting surface, and 3) ease of implantation. The housing for the pump is a tube, 37 mm in diameter (maximum) and 33 mm in length. Within the housing there is an impeller with either 10 vanes (33 mm in diameter) or 5 vanes (22 mm in diameter). The impeller is connected to a samarium-cobalt-rare-earth magnet direct current (DC) brushless motor measuring 23.8 mm in diameter and 30.2 mm in length. Sealing is achieved by means of a magnetic fluid seal. A guiding wheel with 4 vanes is located behind the impeller. The pump was studied on a hydraulic mock circulatory system to evaluate its performance characteristics. A pump flow of 6.9 L/min was obtained at a pump differential pressure of 48 mmHg, and flow of 3.1 L/min was obtained at 58 mmHg. The valvo-pump can be made feasible by developing a small, high-output, power motor and an endurable seal, as well as by optimizing the impeller design.

  9. Hydraulic characterization of centrifugal pumps in He I near saturated conditions

    NASA Astrophysics Data System (ADS)

    Baudouy, B.; Takeda, M.; Van Sciver, S. W.

    The hydraulic characteristics of a variable speed liquid helium centrifugal pump in He I near saturated conditions (4.2 K and ˜100 kPa) are presented. Three different housings are tested, a simple impeller housing and two housings with an impeller with an associated screw inducer, to investigate the effect of the inducer and the effect of the diffuser throat diameter dimension on the performance of the pump. The three housings have been tested in an open loop without discharge line. The pressure difference across the pumps and the mass flow rates have been recorded for different pump speeds. We compare the pump performances with predicted values. For different inlet tube length, cavitation effects, that might occur near saturated conditions, were also investigated.

  10. Variations in battery life of a heart-lung machine using different pump speeds, pressure loads, boot material, centrifugal pump head, multiple pump usage, and battery age.

    PubMed

    Marshall, Cornelius; Hargrove, Martin; O'Donnell, Aonghus; Aherne, Thomas

    2005-09-01

    Electrical failure during cardiopulmonary bypass (CPB) has previously been reported to occur in 1 of every 1500 cases. Most heart-lung machine pump consoles are equipped with built-in battery back-up units. Battery run times of these devices are variable and have not been reported. Different conditions of use can extend battery life in the event of electrical failure. This study was designed to examine the run time of a fully charged battery under various conditions of pump speed, pressure loads, pump boot material, multiple pump usage, and battery life. Battery life using a centrifugal pump also was examined. The results of this study show that battery life is affected by pump speed, circuit pressure, boot stiffness, and the number of pumps in service. Centrifugal pumps also show a reduced drain on battery when compared with roller pumps. These elements affect the longevity and performance of the battery. This information could be of value to the individual during power failure as these are variables that can affect the battery life during such a challenging scenario.

  11. Theoretical, numerical and experimental investigation of centrifugal pumps in reverse operation

    SciTech Connect

    Derakhshan, Shahram; Nourbakhsh, Ahmad

    2008-09-15

    When a pump works as a turbine, its hydraulic behavior will be changed. Several methods have been developed to predict the best efficiency of pumps running as turbines but their results are not in good coincidence with experimental data for all pumps. Therefore, study and investigation of hydraulic behavior of pumps in reverse operation can be useful. In this study, the best efficiency point of an industrial centrifugal pump running as turbine was achieved using a theoretical analysis. This method tries to estimate hydraulic components of reverse (turbine) mode using direct (pump) mode. In the next step, the pump was simulated in direct and reverse modes by computational fluid dynamics. 3D full Navier-Stokes equations were solved using FineTurbo V.7 flow solver. Using numerical results, complete characteristic curves of the pump in direct and reverse modes were obtained. For experimental verification of theoretical and numerical results, the pump was tested as a turbine in a test rig. All required parameters were measured to achieve complete characteristic curves of the reverse pump. The theoretical and numerical results were compared with experimental data and some other methods. (author)

  12. Unsteady flow characteristic of low-specific-speed centrifugal pump under different flow-rate conditions

    NASA Astrophysics Data System (ADS)

    Cui, Baoling; Chen, Desheng; Xu, Wenjing; Jin, Yingzi; Zhu, Zuchao

    2015-02-01

    To investigate the unsteady flow characteristics in centrifugal pump, the flow field in a low-specific-speed centrifugal pump with complex impeller is numerically simulated under different conditions. The RNG κ-ɛ turbulence model and sliding mesh are adopted during the process of computation. The results show that the interaction between impeller and volute results in the unstable flow of the fluid, which causes the uneven distribution of pressure fluctuations around the circumference of volute. Besides the main frequency and its multiple frequency of pressure fluctuations in the centrifugal pump, the frequency caused by the long blades of complex impeller also plays a dominant role in the low-frequency areas. Furthermore, there exists biggish fluctuation phenomenon near the tongue. The composition of static pressure fluctuations frequency on the volute wall and blade outlet is similar except that the fluctuation amplitude near the volute wall reduces. In general, the different flow rates mainly have influence on the amplitude of fluctuation frequency in the pump, while have little effect on the frequency composition.

  13. A new method of providing pulsatile flow in a centrifugal pump: assessment of pulsatility using a mock circulatory system.

    PubMed

    Herreros, Jesús; Berjano, Enrique J; Sales-Nebot, Laura; Más, Pedro; Calvo, Irene; Mastrobuoni, Stefano; Mercé, Salvador

    2008-06-01

    Previous studies have demonstrated the potential advantages of pulsatile flow as compared with continuous flow. However, to date, physiologic pumps have been technically complex and their application has therefore remained in the experimental field. We have developed a new type of centrifugal pump, which can provide pulsatile as well as continuous flow. The inner wall of a centrifugal pump is pulsed by means of a flexible membrane, which can be accurately controlled by means of either a hydraulic or pneumatic driver. The aim of this study was to assess the hydraulic behavior of the new pump in terms of surplus hemodynamic energy (SHE). We conducted experiments using a mock circulatory system including a membrane oxygenator. No differences were found in the pressure-flow characteristics between the new pump and a conventional centrifugal pump, suggesting that the inclusion of the flexible membrane does not alter hydraulic performance. The value of SHE rose when systolic volume was increased. However, SHE dropped when the percentage of ejection time was reduced and also when the continuous flow (programmed by the centrifugal console) increased. Mean flow matched well with the continuous flow set by the centrifugal console, that is, the pulsatile component of the flow was exclusively controlled by the pulsatile console, and was therefore independent of the continuous flow programmed by the centrifugal console. The pulsatility of the new pump was approximately 25% of that created with a truly pulsatile pump.

  14. Centrifugal and Axial Pump Design and Off-Design Performance Prediction

    NASA Technical Reports Server (NTRS)

    Veres, Joseph P.

    1995-01-01

    A meanline pump-flow modeling method has been developed to provide a fast capability for modeling pumps of cryogenic rocket engines. Based on this method, a meanline pump-flow code PUMPA was written that can predict the performance of pumps at off-design operating conditions, given the loss of the diffusion system at the design point. The design-point rotor efficiency and slip factors are obtained from empirical correlations to rotor-specific speed and geometry. The pump code can model axial, inducer, mixed-flow, and centrifugal pumps and can model multistage pumps in series. The rapid input setup and computer run time for this meanline pump flow code make it an effective analysis and conceptual design tool. The map-generation capabilities of the code provide the information needed for interfacing with a rocket engine system modeling code. The off-design and multistage modeling capabilities of PUMPA permit the user to do parametric design space exploration of candidate pump configurations and to provide head-flow maps for engine system evaluation.

  15. Blood warming, pump heating and haemolysis in low-flow extracorporeal life support; an in vitro study using freshly donated human blood.

    PubMed

    Kusters, R W J; Simons, A P; Lancé, M D; Ganushchak, Y M; Bekers, O; Weerwind, P W

    2017-01-01

    Low-flow extracorporeal life support can be used for cardiopulmonary support of paediatric and neonatal patients and is also emerging as a therapy for patients suffering from exacerbation of chronic obstructive pulmonary disease. However, pump heating and haemolysis have proven to negatively affect the system and outcome. This in vitro study aimed at gaining insight into blood warming, pump heating and haemolysis related to the performance of a new low-flow centrifugal pump. Pump performance in the 400-1,500 ml/min flow range was modulated using small-sized dual-lumen catheters and freshly donated human blood. Measurements included plasma free haemoglobin, blood temperature, pump speed, pump pressure, blood flow and thermographic imaging. Blood warming (ΔTmax=0.5°C) had no relationship with pump performance or haemolysis (R(2)max=0.05). Pump performance-related parameters revealed no relevant relationships with haemolysis (R(2)max=0.36). Thermography showed no relevant heat zones in the pump (Tmax=36°C). Concerning blood warming, pump heating and haemolysis, we deem the centrifugal pump applicable for low-flow extracorporeal circulation.

  16. Numerical and Experimental Investigation of Cavitating Characteristics in Centrifugal Pump with Gap Impeller

    NASA Astrophysics Data System (ADS)

    Zhu, Bing; Chen, Hongxun; Wei, Qun

    2014-06-01

    This paper is to study the cavitating characteristics in a low specific speed centrifugal pump with gap structure impeller experimentally and numerically. A scalable DES numerical method is proposed and developed by introducing the von Karman scale instead of the local grid scale, which can switch at the RANS and LES region interface smoothly and reasonably. The SDES method can detect and grasp unsteady scale flow structures, which were proved by the flow around a triangular prism and the cavitation flow in a centrifugal pump. Through numerical and experimental research, it's shown that the simulated results match qualitatively with tested cavitation performances and visualization patterns, and we can conclude that the gap structure impeller has a superior feature of cavitation suppression. Its mechanism may be the guiding flow feature of the small vice blade and the pressure auto-balance effect of the gap tunnel.

  17. Effect of fluid forces on rotor stability of centrifugal compressors and pumps

    NASA Technical Reports Server (NTRS)

    Colding-Jorgensen, J.

    1980-01-01

    A simple two dimensional model for calculating the rotordynamic effects of the impeller force in centrifugal compressors and pumps is presented. It is based on potential flow theory with singularities. Equivalent stiffness and damping coefficients are calculated for a machine with a vaneless volute formed as a logarithmic spiral. It is shown that for certain operating conditions, the impeller force has a destablizing effect on the rotor.

  18. Cavitation characteristics of a small centrifugal pump in He I and He II

    NASA Astrophysics Data System (ADS)

    Ludtke, P. R.; Daney, D. E.

    1988-02-01

    The cavitation characteristics of a small preinduced centrifugal pump operating in He I and He II over the temperature range 1.8-4.2 K are presented. The pump and close-coupled induction motor operate immersed in liquid helium. A six-blade propeller inducer and a three-blade screw inducer were both tested. With this pump configuration using either inducer, there is a tremendous difference between the cavitation characteristics of He I and He II. The net positive suction head requirements for this pump with the screw inducer could not be determined for He I, but it is less than -100 mm and, depending on flow rate, ranges between 35 and 165 mm for He II.

  19. A 2.5D Single Passage CFD Model for Centrifugal Pumps

    NASA Technical Reports Server (NTRS)

    Nakamura S.; Ding, W.; Yano, K.

    1998-01-01

    This paper describes the single passage model based on CFD to analyze the flow in blade passages of a centrifugal pump. The model consists of the flow passage between two impeller blades and the spaces in the inlet eye as well as in the volute. The incompressible Navier-Stokes equations in the conservation form are solved by a finite difference method. The code is designed to investigate the velocity and pressure distributions and intended to investigate how the pump design affects fluid flow through the rotor as well as the pump performance. An early part of the paper investigates the behavior of the model as well as validity of the assumptions made in the model. Then, applications to a rotodynamic heart pump are presented.

  20. Cavitation characteristics of a small centrifugal pump in He I and He II

    NASA Technical Reports Server (NTRS)

    Ludtke, P. R.; Daney, D. E.

    1988-01-01

    The cavitation characteristics of a small preinduced centrifugal pump operating in He I and He II over the temperature range 1.8-4.2 K are presented. The pump and close-coupled induction motor operate immersed in liquid helium. A six-blade propeller inducer and a three-blade screw inducer were both tested. With this pump configuration using either inducer, there is a tremendous difference between the cavitation characteristics of He I and He II. The net positive suction head requirements for this pump with the screw inducer could not be determined for He I, but it is less than -100 mm and, depending on flow rate, ranges between 35 and 165 mm for He II.

  1. Experimental investigation of rotor-stator interaction in a centrifugal pump with several vaned diffusers

    NASA Technical Reports Server (NTRS)

    Arndt, N.; Acosta, A. J.; Brennen, C. E.; Caughey, T. K.

    1990-01-01

    Steady and unsteady diffuser vane pressure measurements have been conducted with a two-dimensional test impeller, in an experimental investigation of rotor-stator interaction within a centrifugal pump having several vaned diffusers, under conditions of different flow coefficients and different radial gaps between the impeller blade trailing edge and the diffuser vane leading edge. The largest pressure fluctuations on the diffuser vanes and the impeller blades were found to be of the same order of magnitude as the total pressure rise across the pump. Increasing the number of diffuser vanes was found to result in a significant decrease of impeller blade pressure fluctuations.

  2. Enhancement of hemocompatibility of the MERA monopivot centrifugal pump: toward medium-term use.

    PubMed

    Yamane, Takashi; Kosaka, Ryo; Nishida, Masahiro; Maruyama, Osamu; Yamamoto, Yoshihiro; Kuwana, Katsuyuki; Kawamura, Hiroshi; Shiraishi, Yasuyuki; Yambe, Tomoyuki; Sankai, Yoshiyuki; Tsutsui, Tatsuo

    2013-02-01

    The MERA monopivot centrifugal pump has been developed for use in open-heart surgery, circulatory support, and bridge-to-decision for up to 4 weeks. The pump has a closed-type, 50-mm diameter impeller with four straight paths. The impeller is supported by a monopivot bearing and is driven by a radial-flux magnet-coupling motor. Because flow visualization experiments have clarified sufficient pivot wash and stagnation at the sharp corner of the pivot support was suggested, sharp corners were removed in the design stage. The index of hemolysis of the pump operating at more than 200 mm Hg was found to be lower than that of a commercial pump. Four-week animal tests were then conducted two times; improvement of thrombus formation was seen in the female pivot through modification of female pivot geometry. Overall antithrombogenicity was also recorded. Finally, to assure mid-term use, an additional 4-week durability test revealed that the rate of the axial pivot wear was as small as 1.1 µm/day. The present in vitro and in vivo studies revealed that the MERA monopivot centrifugal pump has sufficient hemocompatibility and durability for up to 4 weeks.

  3. Two-phase velocity distributions and overall performance of a centrifugal slurry pump

    SciTech Connect

    Cader, T.; Masbernat, O.; Roco, M.C. . Dept. of Mechanical Engineering)

    1994-06-01

    Back-scattering LDV has been used to investigate particulate two-phase flow in a centrifugal slurry pump. The measurements reported here have been made with a dilute suspension of 0.8 mm glass beads at the impeller-casing flow interface. This interface is of practical importance because the corresponding velocity and concentration results can be used to determine the pump head and flowrate. The present study evaluates the connection between the liquid and solids velocity distribution measured around the impeller and the pump performance determined from measurements at the pump inlet and outlet. The analysis of the velocity triangles for both phases shows the effect of the pump flowrate and inlet recirculation on the pump head at the impeller outlet, as well as the effect of particle slip on pump energy efficiency. A separate group of characteristic curves is proposed to represent the periodical fluctuations of the pump flowrate, head, and loss of efficiency due to particle slip, as a function of the impeller position.

  4. An original versatile nonocclusive pressure-regulated blood roller pump for extracorporeal perfusion.

    PubMed

    Durandy, Yves; Wang, Shigang; Ündar, Akif

    2014-06-01

    Currently, only a small number of centrifugal pumps are being used for hemodynamic and/or respiratory support, but all of them have limitations. This article aims to present the Rhône-Poulenc 06 nonocclusive pressure-regulated blood pump. This pump was developed in France in the 1970s and used for decades in perfusion for cardiopulmonary bypass procedures, cardiac or lung assist as well as venovenous bypass during liver transplant. The intrinsic properties of this pump allowed us to describe a new technique for extracorporeal lung support in the 1980s, using a single cannula tidal flow venovenous bypass. This pump compared favorably with conventional pumps in terms of flow and pressure, hemolysis, pulsatility, safety, and cost-effectiveness. We believe that this simple pump could be an alternative to more sophisticated and expensive devices.

  5. Dynamic stress analysis of sewage centrifugal pump impeller based on two-way coupling method

    NASA Astrophysics Data System (ADS)

    Pei, Ji; Yuan, Shouqi; Yuan, Jianping

    2014-03-01

    Current research on the operational reliability of centrifugal pumps has mainly focused on hydrodynamic instability. However, the interaction between the fluid and structure has not been sufficiently considered; this interaction can cause vibration and dynamic stress, which can affect the reliability. In this study, the dynamic stresses in a single-blade centrifugal pump impeller are analysed under different operating conditions; the two-way coupling method is used to calculate the fluid-structure interaction. Three-dimensional unsteady Reynolds-averaged Navier-Stokes equations are solved with the SST k-ω turbulence model for the fluid in the whole flow passage, while transient structure dynamic analysis is used with the finite element method for the structure side. The dynamic stresses in the rotor system are computed according to the fourth strength theory. The stress results show that the highest stress is near the loose bearing and that the equivalent stress increases with the flow rate because the dynamic stresses are closely related to the pressure load. The stress distributions on the blade pressure side, suction side, leading edge, and trailing edge are each analysed for different flow rates; the highest stress distribution is found on the pressure side. On the blade pressure side, a relatively large stress is found near the trailing edge and hub side. Based on these results, a stress distribution prediction method is proposed for centrifugal pumps, which considers the interaction between the fluid and structure. The method can be used to check the dynamic stress at different flow rates when optimising the pump design to increase the pump reliability.

  6. Numerical simulation on dimension decrease for annular casing of one centrifugal boiler circulation pump

    NASA Astrophysics Data System (ADS)

    Fan, Y. Z.; Zuo, Z. G.; Liu, S. H.; Wu, Y. L.; Sha, Y. J.

    2012-11-01

    Primary formulation derivation indicates that the dimension of one existing centrifugal boiler circulation pump casing is too large. As great manufacture cost can be saved by dimension decrease, a numerical simulation research is developed in this paper on dimension decrease for annular casing of this pump with a specific speed equaling to 189, which aims at finding an appropriately smaller dimension of the casing while hydraulic performance and strength performance will hardly be changed according to the requirements of the cooperative company. The research object is one existing centrifugal pump with a diffuser and a semi-spherical annular casing, working as the boiler circulation pump for (ultra) supercritical units in power plants. Dimension decrease, the modification method, is achieved by decreasing the existing casing's internal radius (marked as "Ri0") while keeping the wall thickness. The research analysis is based on primary formulation derivation, CFD (Computational Fluid Dynamics) simulation and FEM (Finite Element Method) simulation. Primary formulation derivation estimates that a design casing's internal radius should be less than 0.75 Ri0. CFD analysis indicates that smaller casing with 0.75 Ri0 has a worse hydraulic performance when working at large flow rates and a better hydraulic performance when working at small flow rates. In consideration of hydraulic performance and dimension decrease, an appropriate casing's internal radius is determined, which equals to 0.875 Ri0. FEM analysis then confirms that modified pump casing has nearly the same strength performance as the existing pump casing. It is concluded that dimension decrease can be an economical method as well as a practical method for large pumps in engineering fields.

  7. Quality evaluation of energy consumed in flow regulation method by speed variation in centrifugal pumps

    NASA Astrophysics Data System (ADS)

    Morales, S.; Culman, M.; Acevedo, C.; Rey, C.

    2014-06-01

    Nowadays, energy efficiency and the Electric Power Quality are two inseparable issues in the evaluation of three-phase induction motors, framed within the program of Rational and Efficient Use of Energy (RUE).The use of efficient energy saving devices has been increasing significantly in RUE programs, for example the use of variable frequency drives (VFD) in pumping systems.The overall objective of the project was to evaluate the impact on power quality and energy efficiency in a centrifugal pump driven by an induction three-phase motor, using the flow control method of speed variation by VFD. The fundamental purpose was to test the opinions continuously heard about the use of flow control methods in centrifugal pumps, analyzing the advantages and disadvantages that have been formulated deliberately in order to offer support to the industry in taking correct decisions. The VFD changes the speed of the motor-pump system increasing efficiency compared to the classical methods of regulation. However, the VFD originates conditions that degrade the quality of the electric power supplied to the system and therefore its efficiency, due to the nonlinearity and presence of harmonic currents. It was possible to analyze the power quality, ensuring that the information that comes to the industry is generally biased.

  8. The analysis of unsteady characteristics in the low specific speed centrifugal pump with drainage gaps

    NASA Astrophysics Data System (ADS)

    Zhu, B.; Chen, H. X.; Wei, Q.; Zhang, R.

    2012-11-01

    The gap drainage impeller is a new structure of impeller which is based on the idea of flow control, and it has been validated in experiments that this structure can increase the pump efficiency. The purpose of this paper is to explore a valid numerical analysis method for the simulation of low specific speed centrifugal pump, and then investigate the unsteady characteristics of the gap drainage impeller pump. The internal flow numerical simulations were done at multi-flow rates, and the calculated results were analyzed based on comparison with the experimental data of hydraulic performance, pressure pulsation and vibration acceleration. It was confirmed that: the results from the simulation tend to agree well with the experiments; the unsteady method is generally superior to the steady method in computing robustness and prediction accuracy at partial flow rates; the wall friction and clearance leakage should be considered in the performance prediction of the low specific centrifugal pump; the frequency spectra of pressure fluctuation is mainly controlled by the rotor-stator interaction, and the overall energy of pressure fluctuation and vibration is increased in part-load working conditions, especially at large flow rates; the pressure pulsation and the impeller radial fluid force are uneven in circumference, and they propagate in the opposite direction of the shaft rotating; however, the calculation error is considerable when comparing with experiments, and the reasons for which should be researched furthermore.

  9. Effects of a left ventricular assist device with a centrifugal pump on left ventricular diastolic hemodynamics.

    PubMed

    Saito, Akira

    2002-10-01

    The purpose of this investigation was to analyze how left ventricular assist device (LVAD) with a centrifugal pump alters left ventricular diastolic hemodynamics and energy by means of a left ventricular pressure volume relationship. Fifteen anesthetized normal pig hearts were studied after placement of an apical drainage LVAD with a centrifugal pump. Indices of the left ventricular isovolumic relaxation phase, left ventricular filling phase and general hemodynamic data were recorded with the LVAD in on and off situations. The pump assist rate was adjusted to 25%, 50% and 75%. Left ventricular stroke work, with a high correlation with oxygen consumption, decreased as the assist rate increased. Left ventricular relaxation delayed as the assist rate increased, but the atrioventricular pressure gradient increased in the left ventricular rapid filling phase. This finding clarifies left ventricular rapid filling. In this study, it was suggested that although left ventricular isovolumic relaxation was affected, 75% assistance is the most effective for the pump flow in terms of circulation support and restoration of cardiac function.

  10. Egg beater as centrifuge: isolating human blood plasma from whole blood in resource-poor settings.

    PubMed

    Wong, Amy P; Gupta, Malancha; Shevkoplyas, Sergey S; Whitesides, George M

    2008-12-01

    This paper demonstrates that a hand-powered egg beater can be modified to serve as a centrifuge for separating plasma from human whole blood. Immunoassays used to diagnose infectious diseases often require plasma from whole blood, and obtaining plasma typically requires electrically-powered centrifuges, which are not widely available in resource-limited settings. Human whole blood was loaded into polyethylene (PE) tubing, and the tubing was attached to the paddle of an egg beater. Spinning the paddle pelleted the blood cells to the distal end of the PE tubing; the plasma remained as the supernatant. A cholesterol assay (run on patterned paper) demonstrated the suitability of this plasma for use in diagnostic assays. The physics of the system was also analyzed as a guide for the selection of other rotating systems for use in centrifugation. Egg beaters, polyethylene tubing, and paper are readily available devices and supplies that can facilitate the use of point-of-care diagnostics at sites far from centralized laboratory facilities.

  11. Fluid seals development for coal liquefaction slurry pumps. Quarterly technical progress report No. 10, 1 January 1985-31 March 1985. [Reciprocating and centrifugal pumps

    SciTech Connect

    Burcham, R.E.

    1985-04-22

    This quarterly progress report covers the work performed during the period January 1, 1985 to March 31, 1985 on the Fluid Seals Development for Coal Liquefaction Slurry Pumps Program. The work was sponsored by the Department of Energy, Pittsburgh Technology Center, to develop technology for hydrostatic fluid seals to be used in coal slurry centrifugal and reciprocating pumps. The scope of the program consists of the following tasks: (1) Task 1A, survey of current practices for centrifugal and reciprocating coal slurry pump seals; (2) Task 1B, preliminary evaluation of three alternative centrifugal and reciprocating fluid seal concepts; (3) Task 2, detail evaluation of the best two centrifugal and reciprocating fluid seal concepts; (4) Task 3A, design and fabrication of the selected centrifugal and reciprocating fluid seal concept, design and fabrication of the centrifugal and reciprocating seal testers; (5) Task 3B, laboratory seal testing of the centrifugal and reciprocating fluid seals; (6) Task 4, field testing of the centrifugal and reciprocating fluid seals. Tasks 1, 2, 3A, and 3B have been completed. Task 4 is pending Department of Energy approval. 2 figs., 1 tab.

  12. Improved Outcome of Cardiac Extracorporeal Membrane Oxygenation in Infants and Children Using Magnetic Levitation Centrifugal Pumps.

    PubMed

    Luciani, Giovanni Battista; Hoxha, Stiljan; Torre, Salvatore; Rungatscher, Alessio; Menon, Tiziano; Barozzi, Luca; Faggian, Giuseppe

    2016-01-01

    Extracorporeal membrane oxygenation (ECMO) has traditionally been and, for the most part, still is being performed using roller pumps. Use of first-generation centrifugal pumps has yielded controversial outcomes, perhaps due to mechanical properties of the same and the ensuing risk of hemolysis and renal morbidity. Latest-generation centrifugal pumps, using magnetic levitation (ML), exhibit mechanical properties which may have overcome limitations of first-generation devices. This retrospective study aimed to assess the safety and efficacy of veno-arterial (V-A) ECMO for cardiac indications in neonates, infants, and children, using standard (SP) and latest-generation ML centrifugal pumps. Between 2002 and 2014, 33 consecutive neonates, infants, and young children were supported using V-A ECMO for cardiac indications. There were 21 males and 12 females, with median age of 29 days (4 days-5 years) and a median body weight of 3.2 kg (1.9-18 kg). Indication for V-A ECMO were acute circulatory collapse in ICU or ward after cardiac repair in 16 (49%) patients, failure to wean after repair of complex congenital heart disease in 9 (27%), fulminant myocarditis in 4 (12%), preoperative sepsis in 2 (6%), and refractory tachy-arrhythmias in 2 (6%). Central cannulation was used in 27 (81%) patients and peripheral in 6. Seven (21%) patients were supported with SP and 26 (79%) with ML centrifugal pumps. Median duration of support was 82 h (range 24-672 h), with 26 (79%) patients weaned from support. Three patients required a second ECMO run but died on support. Seventeen (51%) patients required peritoneal dialysis for acute renal failure. Overall survival to discharge was 39% (13/33 patients). All patients with fulminant myocarditis and with refractory arrhythmias were weaned, and five (83%) survived, whereas no patient supported for sepsis survived. Risk factors for hospital mortality included lower (<2.5 kg) body weight (P = 0.02) and rescue ECMO after cardiac

  13. Computational fluid dynamics of gap flow in a biocentrifugal blood pump.

    PubMed

    Chua, Leok Poh; Song, Guoliang; Yu, Simon Ching Man; Lim, Tau Meng

    2005-08-01

    The centrifugal blood pump with a magnetically suspended impeller has shown its superiority as compared to other artificial heart pumps. However, there is still insufficient understanding of fluid mechanics related issues in the clearance gap. The design nature of the pump requires sufficient washout in the clearance between the impeller and the stationary pump housing inner surface. In this study, numerical simulations were carried out to investigate the flow fields in the gap of the Kyoto-NTN centrifugal blood pump. The flow patterns in the gap region of the blood pump were presented and regions of high and low velocity were identified. It was found that the radial velocity of the blood in the gap was closely related to the pressure distribution at the exit of the impeller, both the highest pressure gradient and the highest radial velocity in the gap occurred at an angular position of 170 degrees . The mass flow rate in the gap was estimated to be 25.2% of the pump outflow, which is close to the measurement results of a five times enlarged test pump. The wall shear stresses on the gap surface were found to be over 21 Pa and below 300 Pa, which is correspondingly higher than the threshold of thrombi formation and is lower than the shearing threshold of red blood cells. Comparison of the 1 : 1 simulation model with the measurement results on a five times enlarged test pump indicates that there are some differences in the resulting radial velocity distributions in the gap and thus the washout mechanism. Two symmetrical high washout regions at both the cutwater and splitter plate were observed in the simulation instead of a single washout region at the splitter plate found in the experimental study. This may be due to the scaling effect of the enlarged test pump; also the medium used in the experiment is different from the simulation.

  14. New inverse method of centrifugal pump blade based on free form deformation

    NASA Astrophysics Data System (ADS)

    Zhang, R. H.; Guo, M.; Yang, J. H.; Liu, Y.; Li, R. N.

    2013-12-01

    In this research, a new inverse method for centrifugal pump blade based on free form deformation is proposed, the free form deformation is used to parametric the pump blade. The blade is implanted to a trivariate control volume which is equally subdivided by control lattice. The control volume can be deformed by moving the control lattice, thereupon the object is deformed. The flow in pump is solved by using a three dimensional turbulent model. The lattice deformation function is constructed according to the gradient distribution of fluid energy along the blade and its objective distribution. Deform the blade shape continually according to the flow solve, and we can get the objective blade shape. The calculation case shows that the proposed inverse method based on FFD method is rational.

  15. Experimental measurements of hydrodynamic radial forces and stiffness matrices for a centrifugal pump-impeller

    NASA Technical Reports Server (NTRS)

    Chamieh, D. S.; Acosta, A. J.; Brennen, C. E.; Caughey, T. K.

    1985-01-01

    Measurements of the steady-state hydrodynamic forces on a centrifugal pump impeller are presented as a function of position within two geometrically different volutes. These correspond to the forces experienced by the impeller at zero whirl frequency. The hydrodynamic force matrices derived from these measurements exhibit both diagonal and off-diagonal terms of substantial magnitude. These terms are of the form which would tend to excite a whirl motion in a rotordynamic analysis of the pump; this may be the cause of 'rough running' reported in many pumps. Static pressure measurements in the impeller discharge flow show that the hydrodynamic force on the impeller contains a substantial component due to the nonisotropy of the net momentum flux leaving the impeller. A similar breakdown of the contributions to the stiffness matrices reveals that the major component of these matrices results from the nonisotropy of the momentum flux.

  16. Centrifugal slurry pump wear and hydraulic studies. Phase II report. Experimental studies

    SciTech Connect

    Mistry, D.; Cooper, P.; Biswas, C.; Sloteman, D.; Onuschak, A.

    1983-01-01

    This report describes the work performed by Ingersoll-Rand Research, Inc., under Phase II, Experimental Studies for the contract entitled, Centrifugal Slurry Pump Wear and Hydraulic Studies. This work was carried out for the US Department of Energy under Contract No. DE-AC-82PC50035. The basic development approach pursued this phase is presented, followed by a discussion on wear relationships. The analysis, which resulted in the development of a mathematical wear model relating pump life to some of the key design and operating parameters, is presented. The results, observations, and conclusions of the experimental investigation on small scale pumps that led to the selected design features for the prototype pump are discussed. The material investigation was performed at IRRI, ORNL and Battelle. The rationale for selecting the materials for testing, the test methods and apparatus used, and the results obtained are presented followed by a discussion on materials for a prototype pump. In addition, the prototype pump test facility description, as well as the related design and equipment details, are presented. 20 references, 53 figures, 13 tables.

  17. Accuracy details in realistic CFD modeling of an industrial centrifugal pump in direct and reverse modes

    NASA Astrophysics Data System (ADS)

    Páscoa, J. C.; Silva, F. J.; Pinheiro, J. S.; Martins, D. J.

    2010-12-01

    Numerical computation of the flowfield inside a pump is herein used as a numerical laboratory, subject to the limitations of modeling assumptions and to experimental verification. A numerical computation of the flow inside a real industrial centrifugal pump is performed that includes a very sophisticated geometry. Conversely to other computations, in this test case no simplification of the geometry was introduced. Numerical computations are obtained using Spalart-Allmaras turbulence model. A detailed analysis of the turbulent flowstructure is performed for the design point and two off design conditions. Additional computations were performed in order to compare the numerical and experimental pump characteristics; these were obtained under normalized testing conditions. Further computations are presented for the pump working in reverse turbine mode (PAT). Detailed analyses of the flow allow a comparison of the internal flow losses when the pump is operating in direct and reverse mode. This is also useful to help in the selection of an adequate pump geometry that can work in both modes with best efficiency.

  18. Hemodynamics on abrupt stoppage of centrifugal pumps during left ventricular assist.

    PubMed

    Kono, S; Nishimura, K; Nishina, T; Akamatsu, T; Komeda, M

    2000-01-01

    A magnetically suspended centrifugal pump (MSCP), developed for long-term ventricular assist, is reliable and durable because it has no shaft or seal. However, with nonvalve pumps such as a MSCP, regurgitation occurs when they accidentally stop without cannula clamping. We investigated the hemodynamics during temporary stoppage of a MSCP being used as a left ventricular assist system (LVAS), comparing two inflow cannulation sites. In four sheep (weight, 35-45 kg), microspheres were injected into the left main coronary artery to induce heart failure. An outflow cannula was sutured onto the descending aorta, and two inflow cannulae were inserted into the left atrium and the left ventricle. The MSCP was stopped with both the left ventricular cannula and left atrial cannula clamped, and the hemodynamics and P-V loops were recorded. Each cannula was then unclamped in order, and similar parameters were recorded. LVEDP increased at unclamping of the left ventricular cannula (ULVC), and rose further at unclamping of the left atrial cannula (ULAC). Aortic pressure did not change at ULVC, but decreased at ULAC. The effective systemic flow that subtracted the regurgitant flow through the MSCP from left ventricular output was half at ULVC and almost 0 at ULAC. When stopping centrifugal pumps without circuit clamping, hemodynamic deterioration is less at ULVC than at ULAC. This finding suggests that left ventricular inflow cannulation is recommended to allow more time in emergency situations.

  19. Measurements of enlarged blood pump models using Laser Doppler Anemometer.

    PubMed

    Chua, L P; Yu, S C; Leo, H L

    2000-01-01

    In an earlier study (Chua et al., 1998, 1999a), a 5:1 enlarged model of the Kyoto-NTN Magnetically Suspended Centrifugal Blood Pump (Akamatsu et al., 1995) with five different impeller blade profiles was designed and constructed. Their respective flow characteristics with respect to (1) the three different blade profile designs: forward, radial, and backward, (2) the number of blades used, and (3) the rotating speed were investigated. Among the five impeller designs, the results obtained suggested that impellers A and C designs should be adopted if higher head is required. Impellers A and C therefore were selected for the flow in between their blades to be measured using Laser Doppler Anemometer (LDA), so as to have a better understanding of the flow physics with respect to the design parameters.

  20. Research on the characteristics of quasi-steady cavitation in a centrifugal pump

    NASA Astrophysics Data System (ADS)

    Lu, J. X.; Yuan, S. Q.; Li, X. J.; Si, Q. R.; Luo, Y.

    2015-01-01

    With the pressure decreasing, the process of cavitation in a centrifugal pump could be summarized as incipient cavitation, quasi-steady cavitation and unsteady cavitation. Quasi-steady cavitation is the condition that is between the incipient cavitation and unsteady cavitation in a centrifugal pump. Under this condition, the intensity of cavitation is relatively weak, and the head of the pump almost remains unchanged, but the cavitation exists, causing damage to the impeller by pitting and erosion. So it is important to investigate the quasi-steady cavitation. In this paper, both the numerical and experimental methods had been carried out to investigate the characteristics of quasi-steady cavitation. The internal flow in the pump, the performance of cavitation and the inlet and outlet pressure pulsation of the pump measured through experimental method have been studied under different NPSHa conditions. It was found that the head decreases about 0.77%-1.38% from non-cavitation condition and it could be regarded as the quasi-steady cavitation. Little change has been found from the internal flow between non-cavitation condition and quasi-steady cavitation condition. The period of inlet pressure pulsation changes from the time that the blade passes by to the period of shaft rotating with the development of cavitation. The dominant frequency of the inlet pressure pulsation is two times of shaft frequency whose amplitudes decrease firstly and then increase to a peak value, followed by a decrease to a low value in quasi-steady cavitation conditions. The dominant frequency of the outlet pressure pulsation is blade passing frequency whose amplitudes increase firstly and then decrease gradually with the decrease of NPSHa.

  1. Modeling erosion in a centrifugal pump in an Eulerian-Lagrangian frame using OpenFOAM®

    NASA Astrophysics Data System (ADS)

    Lopez, Alejandro; Stickland, Matthew; Dempster, William

    2015-07-01

    Erosion induced by solid particle impingement is a very commonwear mechanism in turbomachinery and Computational Fluid Dynamics is one of the most widely used tools for its prediction. In this article, erosion is modeled in one of the channels of a centrifugal pump using OpenFOAM®,which is an Open Source CFD package. A review of some of the most commonly used erosion models is carried out in an Eulerian-Lagrangian frame along with a comparative study of the erosion rates obtained with each model. Results yielded some disparities between models due to the different factors taken into consideration. The mesh is then deformed to obtain the resulting eroded geometry.

  2. Numerical performance evaluation of design modifications on a centrifugal pump impeller running in reverse mode

    NASA Astrophysics Data System (ADS)

    Kassanos, Ioannis; Chrysovergis, Marios; Anagnostopoulos, John; Papantonis, Dimitris; Charalampopoulos, George

    2016-06-01

    In this paper the effect of impeller design variations on the performance of a centrifugal pump running as turbine is presented. Numerical simulations were performed after introducing various modifications in the design for various operating conditions. Specifically, the effects of the inlet edge shape, the meridional channel width, the number of blades and the addition of splitter blades on impeller performance was investigated. The results showed that, an increase in efficiency can be achieved by increasing the number of blades and by introducing splitter blades.

  3. The rotordynamic forces on a centrifugal pump impeller in the presence of cavitation

    NASA Technical Reports Server (NTRS)

    Franz, R.; Acosta, A. J.; Brennen, C. E.; Caughey, T. K.

    1990-01-01

    Fluid-induced rotordynamic forces on a centrifugal pump impeller whirling along a trajectory eccentric to its undeflected position in the presence of cavitation were measured using the experimental facility described by Jery (1987). The force measured is a combination of a steady radial force due to the volute asymmetries and an unsteady force due to the eccentric motion of the rotor. It was found that, compared to the noncavitation condition, a cavitation corresponding to a head loss of 3 percent had little effect upon the unsteady force. However, a lesser degree of cavitation at the design point, was found to increase the destabilizing force for a particular set of whirl ratios.

  4. [Initial experience with a new blood pump].

    PubMed

    Margreiter, R; Schwab, W; Klima, G; Koller, J; Baum, M; Dietrich, H; Hager, J; Königsrainer, A

    1990-12-01

    A new type of blood pump was tested in calves for 6 hours. The pump consists of a rigid housing with a trochoidal internal surface, an inlet and outlet, and two lateral walls. A two-corner piston rotating on an eccentric shaft, describes a trochoidal path, thus creating a gap seal, the gap measuring a constant 10-35 microns. The pump is driven by a watercooled DC motor. For right ventricular assist, a cannula is inserted into the right ventricle through the right atrium, and into the left ventricle for left ventricular assists. From a total of 10 experiments, two left ventricular assists, two right ventricular assists, and three biventricular assists were evaluated. The pump produced a pulsatile flow of 31 at 70 rpm. Energy requirements were 2.19 watts for left, 2.06 for right, and 7.26 for biventricular assists. Plasma hemoglobin remained as low as 10 mg/dl during monoventricular, and increased during biventricular assists to 20 mg/dl after 3 hours, and returned to 16 mg/dl after 6 hours. From these preliminary results it is concluded that this new rotary blood pump may be suitable as a circulatory assist device.

  5. Rotacor: a new rotary blood pump.

    PubMed

    Margreiter, R; Schwab, W; Klima, G; Koller, J; Baum, M; Dietrich, H; Hager, J; Königsrainer, A

    1990-01-01

    A new rotary blood pump was tested in calves for 6 hr. The pump consists of a rigid housing with a trochoidal internal surface, an inlet and outlet, and two lateral walls. A two-corner piston rotates on an eccentric shaft in a trochoidal path, thus creating a gap seal. The pump is driven by a water-cooled DC motor. For right ventricular assist, a cannula was inserted into the right ventricle through the right atrium, and into the left ventricle for left ventricular assist. From a total of 10 experiments, two left ventricular assists, two right ventricular assists, and three biventricular assists were evaluated. The pump produced a pulsatile flow of 3 L at 70 rpm. Energy requirements were 2.19 watts for left, 2.06 for right, and 7.26 for biventricular assists. Plasma hemoglobin remained as low as 10 mg/dl during monoventricular, and increased during biventricular assists to 20 mg/dl after 3 hr, when it started to chop again; after 6 hr it was 16 mg/dl. From these preliminary results it is concluded that this new type of blood pump may be suitable as a circulatory assist device.

  6. Research on the effect of wear-ring clearances to the axial and radial force of a centrifugal pump

    NASA Astrophysics Data System (ADS)

    Zhao, W. G.; Y He, M.; Qi, C. X.; Li, Y. B.

    2013-12-01

    Varying of the wear-ring clearance not only has a distinct effect on the volumetric loss of the centrifugal pump, but also on the performance of the centrifugal pump including the axial and radial forces. Comparing with the experimental studies, numerical simulation methods have some special advantages, such as the low cost, fast and high efficiency, and convenient to get the detailed structure of the internal flow characteristics, so it has been widely used in the fluid machinery study in recent years. In order to study the effect of wear-ring clearance on the force performance of the centrifugal pump, based on the Reynolds Time-Averaged N-S equations and RNG k-ε turbulence model, a centrifugal pump with three variable styles of the wear-rings was simulated: Only the clearance of the front wear-ring was changed, only the clearance of the back wear-ring was changed and both were changed. Comparing with the experiment, numerical results show a good agreement. In the three changing styles of the clearance, the variable of the clearance of front wear-ring has the most influence on the axial force of the centrifugal pump, while has tiny effect on the radial force for all the conditions.

  7. Static stress and modal analysis on the impeller of screw centrifugal pump

    NASA Astrophysics Data System (ADS)

    Yuan, S. Q.; Li, T.; Yuan, J. P.; Zhou, J. J.

    2012-11-01

    The modeling of the screw centrifugal pump was set up with Pro/E, the meshing of the fluid domain and the impeller were completed with ICEM, CFD and Workbench respectively. The 3-D steady turbulence flow in the pump was simulated by using ANSYS CFX under the design condition to get the pressure distribution on the surface of the blades. The static pressure and modal analysis were set using sequential coupling technique based on the simulation result. The results show that the maximum equivalent stress which is far less than the permissible stress occurs at the blade connected with the hub; the maximum deformation of the impeller occurs at the edge of the blade inlet; the deformation domain increase with the frequency ascended.

  8. The effect of inlet swirl on the rotordynamic shroud forces in a centrifugal pump

    NASA Technical Reports Server (NTRS)

    Ginzburg, A.; Brennen, C. E.; Acosta, A. J.; Caughey, T. K.

    1992-01-01

    The role played by fluid forces in determining the rotordynamic stability of a centrifugal pump is gaining increasing attention. The present research investigates the contributions to the rotordynamic forces from the discharge-to-suction leakage flows between the front shroud of the rotating impeller and the stationary pump casing. In particular, the dependency of the rotordynamic characteristics of leakage flows on the swirl at the inlet to the leakage path was examined. An inlet guide vane was designed for the experiment so that swirl could be introduced at the leakage flow inlet. The data demonstrates substantial rotordynamic effects and a destabilizing tangential force for small positive whirl ratios; this force decreased with increasing flow rate. The effect of swirl on the rotordynamic forces was found to be destabilizing.

  9. The effect of inlet swirl on the dynamics of long annular seals in centrifugal pumps

    NASA Technical Reports Server (NTRS)

    Ismail, M.; Brown, R. D.; France, D.

    1994-01-01

    This paper describes additional results from a continuing research program which aims to identify the dynamics of long annular seals in centrifugal pumps. A seal test rig designed at Heriot-Watt University and commissioned at Weir Pumps Research Laboratory in Alloa permits the identification of mass, stiffness, and damping coefficients using a least-squares technique based on the singular value decomposition method. The analysis is carried out in the time domain using a multi-fiequency forcing function. The experimental method relies on the forced excitation of a flexibly supported stator by two hydraulic shakers. Running through the stator embodying two symmetrical balance drum seals is a rigid rotor supported in rolling element bearings. The only physical connection between shaft and stator is the pair of annular gaps filled with pressurized water discharged axially. The experimental coefficients obtained from the tests are compared with theoretical values.

  10. Fluid dynamic characterization of operating conditions for continuous flow blood pumps.

    PubMed

    Wu, Z J; Antaki, J F; Burgreen, G W; Butler, K C; Thomas, D C; Griffith, B P

    1999-01-01

    As continuous flow pumps become more prominent as long-term ventricular assist devices, the wide range of conditions under which they must be operated has become evident. Designed to operate at a single, best-efficiency, operating point, continuous flow pumps are required to perform at off-design conditions quite frequently. The present study investigated the internal fluid dynamics within two representative rotary fluid pumps to characterize the quality of the flow field over a full range of operating conditions. A Nimbus/UoP axial flow blood pump and a small centrifugal pump were used as the study models. Full field visualization of flow features in the two pumps was conducted using a laser based fluorescent particle imaging technique. Experiments were performed under steady flow conditions. Flow patterns at inlet and outlet sections were visualized over a series of operating points. Flow features specific to each pump design were observed to exist under all operating conditions. At off-design conditions, an annular region of reverse flow was commonly observed within the inlet of the axial pump, while a small annulus of backflow in the inlet duct and a strong disturbed flow at the outlet tongue were observed for the centrifugal pump. These observations were correlated to a critical nondimensional flow coefficient. The creation of a "map" of flow behavior provides an additional, important criterion for determining favorable operating speed for rotary blood pumps. Many unfavorable flow features may be avoided by maintaining the flow coefficient above a characteristic critical coefficient for a particular pump, whereas the intrinsic deleterious flow features can only be minimized by design improvement. Broadening the operating range by raising the band between the critical flow coefficient and the designed flow coefficient, is also a worthy goal for design improvement.

  11. Numerical simulation of cavitation effects influenced by centrifugal pump inlet parameters

    NASA Astrophysics Data System (ADS)

    Zhao, L. F.; Wang, Y.; Ning, C.; Liu, Z. C.; Zhu, Z. T.; Xie, S. F.

    2015-01-01

    Cavitation has great influence on performance of the centrifugal pump. However, there is still no effective design to overcome this problem. Blade leading edge of centrifugal pump impeller is the initial position of cavitation. The leading edge geometry shape not only has a great influence on the cavitation inception and its development, but also a great influence on the flow state near the impeller inlet. In this paper, the numerical simulation method is adopted. Cavitation of four different models (including rectangular-shape blade model, circular-arc-shape blade model, elliptical-shape blade model and cusp-shape blade model) are simulated under the same condition by changing the NPSHA value. The influence of different blade models on cavitation performance is analyzed. The results show that the deviation between the simulated data and experimental data is within the deviation range. The head of rectangular-shape blade model and circular-arc-shape blade model are higher than those of elliptical-shape blade model and cusp-shape blade model. However, the head of rectangular-shape blade model and circular-arc-shape blade model is smaller than the latter under the low effective cavitation margin. What's more, the head of the models with trimmed blade are higher than the head of the models with untrimmed blade under the working condition but are smaller under the low effective cavitation margin.

  12. Centrifugal pump support for distal aortic perfusion during repair of traumatic thoracic aortic injury.

    PubMed

    Walls, Joseph T; Curtis, Jack J; McKenney-Knox, Charlotte A; Schmaltz, Richard A

    2002-11-01

    Paraplegia from ischemic injury of the spinal cord and renal failure from inadequate perfusion of the kidneys may occur from aortic cross-clamping during repair of traumatic thoracic aortic injuries. After Institutional Review Board approval, we retrospectively reviewed the charts of 26 patients surgically treated for traumatic transection of the descending thoracic aorta during a 14 year period (1987-2001), using centrifugal pump (Sarns) support for distal aortic perfusion. The study group comprised 19 males and 7 females, whose ages ranged from 15 to 69 years. For all but 1 patient, who fell from a flagpole, the injuries were incurred in motor vehicle accidents. Aortic cross-clamp time lasted between 5 to 78 min (median = 40 min). Mean arterial pressure ranged from 50 to 80 mm Hg (median = 70 mm Hg). All patients survived operation without developing paraplegia or renal failure. Distal centrifugal pump perfusion during repair of traumatic injury of the descending thoracic aorta is a valuable adjunct during surgical treatment and aids in preservation of spinal cord and renal function.

  13. Numerical Simulation of Cavitation in a Centrifugal Pump at Low Flow Rate

    NASA Astrophysics Data System (ADS)

    Tan, Lei; Cao, Shu-Liang; Wang, Yu-Ming; Zhu, Bao-Shan

    2012-01-01

    Based on the full cavitation model which adopts homogeneous flow supposition and considering the compressibility effect on cavitation flow to modify the re-normalization group k-in turbulence model by the density function, a computational model is developed to simulate cavitation flow of a centrifugal pump at low flow rate. The Navier-Stokes equation is solved with the SIMPLEC algorithm. The calculated curves of net positive suction head available (NPSHa) HNPSHa agree well with the experimental data. The critical point of cavitation in centrifugal pump can be predicted precisely, and the NPSH critical values derived from simulation are consistent with the experimental data. Thus the veracity and reliability of this computational model are verified. Based on the result of numerical simulation, the distribution of vapor volume fraction in the impeller and pressure at the impeller inlet are analyzed. Cavities first appear on the suction side of the blade head near the front shroud. A large number of cavities block the impeller channels, which leads to the sudden drop of head at the cavitation critical point. With the reduction of NPSHa, the distribution of pressure at the impeller inlet is more uniform.

  14. Suppression of the secondary flow in a suction channel of a large centrifugal pump

    NASA Astrophysics Data System (ADS)

    Torii, D.; Nagahara, T.; Okihara, T.

    2013-12-01

    The suction channel configuration of a large centrifugal pump with a 90-degree bend was studied in detail to suppress the secondary flow at the impeller inlet for improving suction performance. Design of experiments (DOE) and computational fluid dynamics (CFD) were used to evaluate the sensitivity of several primary design parameters of the suction channel. A DOE is a powerful tool to clarify the sensitivity of objective functions to design parameters with a minimum of trials. An L9 orthogonal array was adopted in this study and nine suction channels were designed, through which the flow was predicted by steady state calculation. The results indicate that a smaller bend radius with a longer straight nozzle, distributed between the bend and the impeller, suppresses the secondary flow at the impeller inlet. An optimum ratio of the cross sectional areas at the bend inlet and outlet was also confirmed in relationship to the contraction rate of the downstream straight nozzle. These findings were obtained by CFD and verified by experiments. The results will aid the design of large centrifugal pumps with better suction performance and higher reliability.

  15. Fluid Dynamics in Rotary Piston Blood Pumps.

    PubMed

    Wappenschmidt, Johannes; Sonntag, Simon J; Buesen, Martin; Gross-Hardt, Sascha; Kaufmann, Tim; Schmitz-Rode, Thomas; Autschbach, Ruediger; Goetzenich, Andreas

    2017-03-01

    Mechanical circulatory support can maintain a sufficient blood circulation if the native heart is failing. The first implantable devices were displacement pumps with membranes. They were able to provide a sufficient blood flow, yet, were limited because of size and low durability. Rotary pumps have resolved these technical drawbacks, enabled a growing number of mechanical circulatory support therapy and a safer application. However, clinical complications like gastrointestinal bleeding, aortic insufficiency, thromboembolic complications, and impaired renal function are observed with their application. This is traced back to their working principle with attenuated or non-pulsatile flow and high shear stress. Rotary piston pumps potentially merge the benefits of available pump types and seem to avoid their complications. However, a profound assessment and their development requires the knowledge of the flow characteristics. This study aimed at their investigation. A functional model was manufactured and investigated with particle image velocimetry. Furthermore, a fluid-structure interaction computational simulation was established to extend the laboratory capabilities. The numerical results precisely converged with the laboratory measurements. Thus, the in silico model enabled the investigation of relevant areas like gap flows that were hardly feasible with laboratory means. Moreover, an economic method for the investigation of design variations was established.

  16. Clinical effectiveness of centrifugal pump to produce pulsatile flow during cardiopulmonary bypass in patients undergoing cardiac surgery.

    PubMed

    Gu, Y John; van Oeveren, Willem; Mungroop, Hubert E; Epema, Anne H; den Hamer, Inez J; Keizer, Jorrit J; Leuvenink, Ron P; Mariani, Massimo A; Rakhorst, Gerhard

    2011-02-01

    Although the centrifugal pump has been widely used as a nonpulsatile pump for cardiopulmonary bypass (CPB), little is known about its performance as a pulsatile pump for CPB, especially on its efficacy in producing hemodynamic energy and its clinical effectiveness. We performed a study to evaluate whether the Rotaflow centrifugal pump produces effective pulsatile flow during CPB and whether the pulsatile flow in this setting is clinically effective in adult patients undergoing cardiac surgery. Thirty-two patients undergoing CPB for elective coronary artery bypass grafting were randomly allocated to a pulsatile perfusion group (n = 16) or a nonpulsatile perfusion group (n = 16). All patients were perfused with the Rotaflow centrifugal pump. In the pulsatile group, the centrifugal pump was adjusted to the pulsatile mode (60 cycles/min) during aortic cross-clamping, whereas in the nonpulsatile group, the pump was kept in its nonpulsatile mode during the same period of time. Compared with the nonpulsatile group, the pulsatile group had a higher pulse pressure (P < 0.01) and a fraction higher energy equivalent pressure (EEP, P = 0.058). The net gain of pulsatile flow, represented by the surplus hemodynamic energy (SHE), was found much higher in the CPB circuit than in patients (P < 0.01). Clinically, there was no difference between the pulsatile and nonpulsatile groups with regard to postoperative acute kidney injury, endothelial activation, or inflammatory response. Postoperative organ function and the duration of hospital stay were similar in the two patient groups. In conclusion, pulsatile CPB with the Rotaflow centrifugal pump is associated with a small gain of EEP and SHE, which does not seem to be clinically effective in adult cardiac surgical patients.

  17. Optimization on the impeller of a low-specific-speed centrifugal pump for hydraulic performance improvement

    NASA Astrophysics Data System (ADS)

    Pei, Ji; Wang, Wenjie; Yuan, Shouqi; Zhang, Jinfeng

    2016-09-01

    In order to widen the high-efficiency operating range of a low-specific-speed centrifugal pump, an optimization process for considering efficiencies under 1.0 Q d and 1.4 Q d is proposed. Three parameters, namely, the blade outlet width b 2, blade outlet angle β 2, and blade wrap angle φ, are selected as design variables. Impellers are generated using the optimal Latin hypercube sampling method. The pump efficiencies are calculated using the software CFX 14.5 at two operating points selected as objectives. Surrogate models are also constructed to analyze the relationship between the objectives and the design variables. Finally, the particle swarm optimization algorithm is applied to calculate the surrogate model to determine the best combination of the impeller parameters. The results show that the performance curve predicted by numerical simulation has a good agreement with the experimental results. Compared with the efficiencies of the original impeller, the hydraulic efficiencies of the optimized impeller are increased by 4.18% and 0.62% under 1.0 Q d and 1.4Qd, respectively. The comparison of inner flow between the original pump and optimized one illustrates the improvement of performance. The optimization process can provide a useful reference on performance improvement of other pumps, even on reduction of pressure fluctuations.

  18. Analysis of silt abrasion of the impeller ring in a centrifugal pump with J-grooves

    NASA Astrophysics Data System (ADS)

    Qian, Z. D.; Wang, Z. Y.; Guo, Z. W.; Dong, J.; Lu, J.

    2016-05-01

    The water flow and movement of silt in a prototype double-suction centrifugal pump was simulated using an Euler-Lagrange multiphase flow model. J-Grooves were adopted to protect the impeller ring from silt abrasion. The influence of J-grooves on the silt concentration and pump efficiency was analyzed. The results show that the radial component of the relative velocity around the impeller ring is too low to move the silt out of the spacing between the impeller plate and the casing. The high silt concentration around the impeller ring is the major contributor to silt abrasion of the impeller ring. The J-grooves induce two strong vortices, which increase the radial component of the relative velocity of water and reduce the silt concentration around the impeller ring, but additional friction losses are introduced and the pump efficiency is decreased. Optimization of the number and shape of J-grooves decreases losses in the efficiency of the pump, and effectively protects the impeller ring. Case 4 was found the most effective configuration in this study.

  19. Computational fluid dynamics analysis of blade tip clearances on hemodynamic performance and blood damage in a centrifugal ventricular assist device.

    PubMed

    Wu, Jingchun; Paden, Bradley E; Borovetz, Harvey S; Antaki, James F

    2010-05-01

    An important challenge facing the design of turbodynamic ventricular assist devices (VADs) intended for long-term support is the optimization of the flow path geometry to maximize hydraulic performance while minimizing shear-stress-induced hemolysis and thrombosis. For unshrouded centrifugal, mixed-flow and axial-flow blood pumps, the complex flow patterns within the blade tip clearance between the lengthwise upper surface of the rotating impeller blades and the stationary pump housing have a dramatic effect on both the hydrodynamic performance and the blood damage production. Detailed computational fluid dynamics (CFD) analyses were performed in this study to investigate such flow behavior in blade tip clearance region for a centrifugal blood pump representing a scaled-up version of a prototype pediatric VAD. Nominal flow conditions were analyzed at a flow rate of 2.5 L/min and rotor speed of 3000 rpm with three blade tip clearances of 50, 100, and 200 microm. CFD simulations predicted a decrease in the averaged tip leakage flow rate and an increase in pump head and axial thrust with decreasing blade tip clearances from 200 to 50 microm. The predicted hemolysis, however, exhibited a unimodal relationship, having a minimum at 100 microm compared to 50 microm and 200 microm. Experimental data corroborate these predictions. Detailed flow patterns observed in this study revealed interesting fluid dynamic features associated with the blade tip clearances, such as the generation and dissipation of tip leakage vortex and its interaction with the primary flow in the blade-blade passages. Quantitative calculations suggested the existence of an optimal blade tip clearance by which hydraulic efficiency can be maximized and hemolysis minimized.

  20. Computational Fluid Dynamics Analysis of Blade Tip Clearances on Hemodynamic Performance and Blood Damage in a Centrifugal Ventricular Assist Device

    PubMed Central

    Wu, Jingchun; Paden, Bradley E.; Borovetz, Harvey S.; Antaki, James F.

    2011-01-01

    An important challenge facing the design of turbodynamic ventricular assist devices (VADs) intended for long-term support is the optimization of the flow path geometry to maximize hydraulic performance while minimizing shear-stress-induced hemolysis and thrombosis. For unshrouded centrifugal, mixed-flow and axial-flow blood pumps, the complex flow patterns within the blade tip clearance between the lengthwise upper surface of the rotating impeller blades and the stationary pump housing have a dramatic effect on both the hydrodynamic performance and the blood damage production. Detailed computational fluid dynamics (CFD) analyses were performed in this study to investigate such flow behavior in blade tip clearance region for a centrifugal blood pump representing a scaled-up version of a prototype pediatric VAD. Nominal flow conditions were analyzed at a flow rate of 2.5 L/min and rotor speed of 3000 rpm with three blade tip clearances of 50, 100, and 200 μm. CFD simulations predicted a decrease in the averaged tip leakage flow rate and an increase in pump head and axial thrust with decreasing blade tip clearances from 200 to 50 μm. The predicted hemolysis, however, exhibited a unimodal relationship, having a minimum at 100 μm compared to 50 μm and 200 μm. Experimental data corroborate these predictions. Detailed flow patterns observed in this study revealed interesting fluid dynamic features associated with the blade tip clearances, such as the generation and dissipation of tip leakage vortex and its interaction with the primary flow in the blade-blade passages. Quantitative calculations suggested the existence of an optimal blade tip clearance by which hydraulic efficiency can be maximized and hemolysis minimized. PMID:19832736

  1. Effect of hypergravity on catecholamine levels in telemetrically collected blood of rats during centrifugation

    NASA Astrophysics Data System (ADS)

    Kvetnansky, R.; Petrak, J.; Mravec, B.; Tillinger, A.; Jurani, M.; Baranovska, M.; Hapala, I.; Frollo, I.

    2005-08-01

    Hypergravity is known to activate the sympathoadrenal system (SAS). Rats subjected to various accelerations (+G) exhibited increased levels of plasma epinephrine (EPI) and partly also norepinephrine (NE). However, the collection of blood was performed after centrifugation finished and therefore plasma NE and EPI levels could have been affected by the process of deceleration. The aim of this study was to evaluate plasma EPI and NE levels in blood collected directly during the centrifugation after reaching different +G, using newly developed remote controlled equipment. Such telemetrically regulated equipment for multiple blood sampling allows us to investigate selective effects of hypergravity during centrifugation. All animals had a polyethylene tubing in the tail artery which was connected to a pre-programmed device for three blood withdrawals (0.6 ml each) into individual syringes, performed at any chosen time intervals. Plasma EPI and NE levels were measured at hypergravity between +1G - +5G. Plasma EPI levels showed a huge, hypergravity dependent increase at the interval of 10-20 min. After the blood collection was completed, the centrifuge was turned off and another blood sampling was performed immediately after the centrifuge stopped (10 min). In these samples plasma EPI levels showed a significant reduction compared to the 20 min interval of centrifugation but the EPI levels at 4G-6G were still significantly elevated compared to pre- centrifugation levels. Plasma NE levels showed less pronounced changes (increased after 6G only) with a slower return to control levels.Thus, our data has shown completely different responses of the adrenomedullary (epinephrine) and sympathoneural (norepinephrine) systems to hypergravitation. This data shows that the increased gravitation and not the stressful situations connected with centrifugation is the factor responsible for massive activation of the adrenomedullary system. The mechanism of small activation of the

  2. Impeller behavior and displacement of the VentrAssist implantable rotary blood pump.

    PubMed

    Chung, Michael K H; Zhang, Nong; Tansley, Geoff D; Woodard, John C

    2004-03-01

    The VentrAssist implantable rotary blood pump, intended for long-term ventricular assist, is under development and is currently being tested for its rotor-dynamic stability. The pump is of the centrifugal type and consists of a shaftless impeller, also acting as the rotor of the brushless DC motor. The impeller remains passively suspended in the pump cavity by hydrodynamic forces, resulting from the small clearances between the impeller outside surfaces and the pump cavity. In the older version of the pump tested, these small clearances range from approximately 50 microm to 230 microm; the displacement of the impeller relative to the pump cavity is unknown in use. This article presents two experiments: the first measured displacement of the impeller using eddy-current proximity sensors and laser proximity sensors. The second experiment used Hall-effect proximity sensors to measure the displacement of the impeller relative to the pump cavity. All transducers were calibrated prior to commencement of the experiments. Voltage output from the transducers was converted into impeller movement in five degrees of freedom (x, y, z, theta(x), and theta(y)). The sixth degree of freedom, the rotation about the impeller axis (theta(z)), was determined by the commutation performed by the motor controller. The impeller displacement was found to be within the acceptable range of 8 micro m to 222 microm, avoiding blood damage and contact between the impeller and cavity walls. Thus the impeller was hydrodynamically suspended within the pump cavity and results were typical of centrifugal pump behavior. This research will be the basis for further investigation into the stiffness and damping coefficient of the pump's hydrodynamic bearing.

  3. New mechanism to reduce the size of the monopivot magnetic suspension blood pump: direct drive mechanism.

    PubMed

    Yamane, T; Nishida, M; Kijima, T; Maekawa, J

    1997-07-01

    Size reduction of the monopivot magnetic suspension blood pump has been achieved by reducing the size of the magnetic suspension and employing a direct drive mechanism in place of a brushless DC motor and a magnetic coupling. The flow has also been improved using a closed hollow impeller to remove flow obstruction at the inlet and using radial straight vanes to reduce the impeller speed by 30%. Hemolysis testing was conducted for the new models. Results showed that model DD1 presented only a slightly higher level of hemolysis than a regular extracorporeal centrifugal pump.

  4. Effect of blade outlet angle on radial thrust of single-blade centrifugal pump

    NASA Astrophysics Data System (ADS)

    Nishi, Y.; Fukutomi, J.; Fujiwara, R.

    2012-11-01

    Single-blade centrifugal pumps are widely used as sewage pumps. However, a large radial thrust acts on a single blade during pump operation because of the geometrical axial asymmetry of the impeller. This radial thrust causes vibrations of the pump shaft, reducing the service life of bearings and shaft seal devices. Therefore, to ensure pump reliability, it is necessary to quantitatively understand the radial thrust and clarify the behavior and generation mechanism. This study investigated the radial thrust acting on two kinds of single-blade centrifugal impellers having different blade outlet angles by experiments and computational fluid dynamics (CFD) analysis. Furthermore, the radial thrust was modeled by a combination of three components, inertia, momentum, and pressure, by applying an unsteady conservation of momentum to this impeller. As a result, the effects of the blade outlet angle on both the radial thrust and the modeled components were clarified. The total head of the impeller with a blade outlet angle of 16 degrees increases more than the impeller with a blade outlet angle of 8 degrees at a large flow rate. In this case, since the static pressure of the circumference of the impeller increases uniformly, the time-averaged value of the radial thrust of both impellers does not change at every flow rate. On the other hand, since the impeller blade loading becomes large, the fluctuation component of the radial thrust of the impeller with the blade outlet angle of 16 degrees increases. If the blade outlet angle increases, the fluctuation component of the inertia component will increase, but the time-averaged value of the inertia component is located near the origin despite changes in the flow rate. The fluctuation component of the momentum component becomes large at all flow rates. Furthermore, although the time-averaged value of the pressure component is almost constant, the fluctuation component of the pressure component becomes large at a large flow rate

  5. PIV pictures of stream field predict haemolysis index of centrifugal pump with streamlined impeller.

    PubMed

    Qian, K X; Feng, Z G; Ru, W M; Zeng, P; Yuan, H Y

    2007-01-01

    Previously it has been found by pump haemolysis testing that the flow rate has a remarkable effect on index of haemolysis (IH), while pressure head does not affect IH. Recent investigation with particle image velocimetry (PIV) technology has demonstrated that IH is directly related to the flow pattern of stream field in impeller vane channels. PIV is a visible approach showing the real flow status in the pump. The different positions of a tracer particle in two PIV pictures taken at 20 micros intervals decide the velocity value and direction. The velocity vectors of many particles draw the flow pattern of the stream field. The same pictures are taken at 2, 4 and 6 l min(-1) flow rates while the pressure head is kept unchanged at 100 mmHg; then the pictures are taken at 4 l min(-1) flow with different pressure heads of 80, 100 and 120 mmHg. Results reveal that the flow rate of 4 l min(-1) (IH = 0.030) has the best stream field, and neither turbulence nor separation can be seen. In other flow rates (IH: 0.048 - 0.082), there is obviously second flow. Meanwhile, no significant difference can be seen among the PIV pictures of different pressure heads pumped, which agrees with the results of haemolysis testing showing that pressure has no effect on pump haemolysis. It may be concluded that the haemolysis property of a centrifugal pump can be assessed approximately by PIV pictures, which are much easier to take than haemolysis tests.

  6. Modeling of a rotary blood pump.

    PubMed

    Nestler, Frank; Bradley, Andrew P; Wilson, Stephen J; Timms, Daniel L

    2014-03-01

    The accurate representation of rotary blood pumps in a numerical environment is important for meaningful investigation of pump-cardiovascular system interactions. Although numerous models for ventricular assist devices (VADs) have been developed, modeling methods for rotary total artificial hearts (rTAHs) are still required. Therefore, an rTAH prototype was characterized in a steady flow, hydraulic test bench over a wide operational range for pump and hydraulic parameters. In order to develop a generic modeling method, a data-driven modeling approach was chosen. k-Nearest-neighbors, artificial neural networks, and support vector machines (SVMs) were the machine learning approaches evaluated. The best performing parameters for each algorithm were determined via optimization. The resulting multiple-input-multiple-output models were subsequently assessed under identical conditions, and a SVM with a radial basis function kernel was identified as the best performing. The achieved root mean squared errors were 0.03 L/min, 0.06 L/min, and 0.18 W for left and right flow and motor power consumption, respectively. In comparison with existing models for VADs, the flow errors are more than 70% lower. Further advantages of the SVM model are the robustness to measurement noise and the capability to operate outside of the trained parameter range. This proposed modeling method will accelerate further device refinements by providing a more appropriate numerical environment in which to evaluate the pump-cardiovascular system interaction.

  7. Numerical Simulation of Pressure Fluctuation around the Tongue Region in a Centrifugal Pump

    NASA Astrophysics Data System (ADS)

    Zheng, L. L.; Dou, H.-S.; Chen, X. P.; Zhu, Z. C.; Cui, B. L.

    2016-11-01

    Pressure fluctuation near the tongue is one of the primary sources of pump vibration and noise. In order to investigate the effect of pressure fluctuation near the tongue, the RANS equations and the RNG k-epsilon turbulence model are employed to simulate the flow in the pump. The SIMPLE algorithm is applied to couple the solutions of the system of equations. Flow field within the centrifugal pump under different flow rates are obtained by simulation. The simulation results are compared with the experimental data to verify the reliability of the calculation model. It is found that the pressure fluctuation at each monitor point is a periodic wave but non-uniform under small flow rate. When the flow rate is larger than the design flow rate, average pressure and standard deviation at monitor points is relative uniform. The dominate frequency of pressure fluctuation is the blade passing frequency and the amplitude of pressure fluctuation is regular. At small flow rate, complex unstable flow makes average pressure and standard deviation at monitor points increasing obviously. Amplitude of pressure fluctuation is larger than that of design flow rate conditions and the maximum amplitude of pressure fluctuation in frequency domain exists at the monitor point just behind the tongue along the impeller rotation direction.

  8. Experimental study of unsteady hydrodynamic force matrices on whirling centrifugal pump impellers. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Belgacem, Jery

    1986-01-01

    An experimental facility was constructed and instrumented. A set of centrifugal flow pumps whose impellers were made to follow a controlled circular whirl motion were studied. The aim was to characterize the steady and unsteady fluid forces measured on the impeller under various pump operating conditions. The postulation was that the unsteady lateral forces result from interactions between the impeller and the surrounding diffuser and/or volute (via the working fluid), and that under certain flow regimes these forces can drive unstable lateral motions of the pump rotor. The lateral hydrodynamic forces were decomposed into their steady and unsteady parts, the latter being further expressed in terms of a generalized fluid stiffness matrix. Conclusions regarding the effect of impeller geometry could not be reached given the similarity of the tested designs. However, other results on phenomena such as skin friction and leakage flow are presented. Some of the findings are compared to experimental and theoretical data from other sources. Finally, the rotordynamic consequences of the results are discussed as the present data were applied to the case of the Space Shuttle Main Engine (SSME) High Pressure Oxidizer Turbopump (HPOTP).

  9. Multi-objective optimization of a low specific speed centrifugal pump using an evolutionary algorithm

    NASA Astrophysics Data System (ADS)

    An, Zhao; Zhounian, Lai; Peng, Wu; Linlin, Cao; Dazhuan, Wu

    2016-07-01

    This paper describes the shape optimization of a low specific speed centrifugal pump at the design point. The target pump has already been manually modified on the basis of empirical knowledge. A genetic algorithm (NSGA-II) with certain enhancements is adopted to improve its performance further with respect to two goals. In order to limit the number of design variables without losing geometric information, the impeller is parametrized using the Bézier curve and a B-spline. Numerical simulation based on a Reynolds averaged Navier-Stokes (RANS) turbulent model is done in parallel to evaluate the flow field. A back-propagating neural network is constructed as a surrogate for performance prediction to save computing time, while initial samples are selected according to an orthogonal array. Then global Pareto-optimal solutions are obtained and analysed. The results manifest that unexpected flow structures, such as the secondary flow on the meridian plane, have diminished or vanished in the optimized pump.

  10. Multi-level 3D implementation of thermo-pneumatic pumping on centrifugal microfluidic CD platforms.

    PubMed

    Thio, Tzer Hwai Gilbert; Ibrahim, Fatimah; Al-Faqheri, Wisam; Soin, Norhayati; Abdul Kahar, Maria Kahar Bador; Madou, Marc

    2013-01-01

    Thermo-pneumatic (TP) pumping is a method employing the principle of expanding heated air to transfer fluids back towards the CD center on the centrifugal microfluidic CD platform. While the TP features are easy to fabricate as no moving parts are involved, it consumes extra real estate on the CD, and because heating is involved, it introduces unnecessary heating to the fluids on the CD. To overcome these limitations, we introduce a multi-level 3D approach and implement forced convection heating. In a multi-level 3D CD, the TP features are relocated to a separate top level, while the microfluidic process remains on a lower bottom level. This allows for heat shielding of the fluids in the microfluidic process level, and also improve usage of space on the CD. To aid in future implementations of TP pumping on a multi-level 3D CD, studies on the effect of heat source setting, and the effect of positioning the TP feature (it distance from the CD center) on CD surface heating are also presented. In this work, we successfully demonstrate a multi-level 3D approach to implement TP pumping on the microfluidic CD platform.

  11. Control and monitoring system for clinically employed pneumatic blood pumps.

    PubMed

    Normann, N A; Henrichsen, D W; Cooper, T G; King, R E; Noon, G P; DeBakey, M E

    1977-01-01

    Instantaneous position of the flexing member in pneumatic blood pumps is monitored on-line by measuring the electrical capacitance across the gas space within the pump. Monitor output is utilized in closed-loop pump control and for automatic pump shutdown in response to operational abnormalities. Thus, safety and efficacy are enhanced through operational optimization, automatic safety features, and facilitated evaluation.

  12. Evaluation of subgrid-scale models in large-eddy simulations of turbulent flow in a centrifugal pump impeller

    NASA Astrophysics Data System (ADS)

    Yang, Zhengjun; Wang, Fujun; Zhou, Peijian

    2012-09-01

    The current research of large eddy simulation (LES) of turbulent flow in pumps mainly concentrates in applying conventional subgrid-scale (SGS) model to simulate turbulent flow, which aims at obtaining the flow field in pump. The selection of SGS model is usually not considered seriously, so the accuracy and efficiency of the simulation cannot be ensured. Three SGS models including Smagorinsky-Lilly model, dynamic Smagorinsky model and dynamic mixed model are comparably studied by using the commercial CFD code Fluent combined with its user define function. The simulations are performed for the turbulent flow in a centrifugal pump impeller. The simulation results indicate that the mean flows predicted by the three SGS models agree well with the experimental data obtained from the test that detailed measurements of the flow inside the rotating passages of a six-bladed shrouded centrifugal pump impeller performed using particle image velocimetry (PIV) and laser Doppler velocimetry (LDV). The comparable results show that dynamic mixed model gives the most accurate results for mean flow in the centrifugal pump impeller. The SGS stress of dynamic mixed model is decompose into the scale similar part and the eddy viscous part. The scale similar part of SGS stress plays a significant role in high curvature regions, such as the leading edge and training edge of pump blade. It is also found that the dynamic mixed model is more adaptive to compute turbulence in the pump impeller. The research results presented is useful to improve the computational accuracy and efficiency of LES for centrifugal pumps, and provide important reference for carrying out simulation in similar fluid machineries.

  13. Numerical and experimental study on flow-induced noise at blade-passing frequency in centrifugal pumps

    NASA Astrophysics Data System (ADS)

    Yang, Jun; Yuan, Shouqi; Yuan, Jianping; Si, Qiaorui; Pei, Ji

    2014-05-01

    With the increasing noise pollution, low noise optimization of centrifugal pimps has become a hot topic. However, experimental study on this problem is unacceptable for industrial applications due to unsustainable cost. A hybrid method that couples computational fluid dynamics (CFD) with computational aeroacoustic software is used to predict the flow-induced noise of pumps in order to minimize the noise of centrifugal pumps in actual projects. Under Langthjem's assumption that the blade surface pressure is the main flow-induced acoustic source in centrifugal pumps, the blade surface pressure pulsation is considered in terms of the acoustical sources and simulated using CFX software. The pressure pulsation and noise distribution in the near-cutoff region are examined for the blade-passing frequency (BPF) noise, and the sound pressure level (SPL) reached peaks near the cutoff that corresponded with the pressure pulsation in this region. An experiment is performed to validate this prediction. Four hydrophones are fixed to the inlet and outlet ports of the test pump to measure the flow-induced noise from the four-port model. The simulation results for the noise are analyzed and compared with the experimental results. The variation in the calculated noise with changes in the flow agreed well with the experimental results. When the flow rate was increased, the SPL first decreased and reached the minimum near the best efficient point (BEP); it then increased when the flow rate was further increased. The numerical and experimental results confirmed that the BPF noise generated by a blade-rotating dipole roughly reflects the acoustic features of centrifugal pumps. The noise simulation method in current study has a good feasibility and suitability, which could be adopted in engineering design to predict and optimize the hydroacoustic behavior of centrifugal pumps.

  14. Feasibility of a tiny Gyro centrifugal pump as an implantable ventricular assist device.

    PubMed

    Yoshikawa, M; Nakata, K; Ohtsuka, G; Takano, T; Glueck, J; Fujisawa, A; Makinouchi, K; Yokokawa, M; Nosé, Y

    1999-08-01

    The Gyro pumps were developed for long-term circulatory support. The first generation Gyro pump (C1E3) achieved 1 month paracorporeal circulatory support in chronic animal experiments; the second generation (PI702) implantable ventricular assist device (VAD) was successful for over 6 months. The objective of the next generation Gyro pump is for use as a long-term totally implantable VAD and for pediatric circulatory support. This tiny Gyro pump (KP101) was fabricated with the same design concept as the other Gyro pumps. The possibility of an implantable VAD was determined after performance and hemolysis test results were compared to those of the other Gyro pumps. The pump housing and impeller were fabricated from polycarbonate with an impeller diameter of 35 mm. The diameter and height of the pump housings are 52.3 mm and 29.9 mm, respectively. At this time, a DC brushless motor drives the KP101, which is the same as that for the C1E3. The pump performance was measured in 37% glycerin water at 37 degrees C. Hemolysis tests were performed utilizing a compact mock loop filled with fresh bovine blood in a left ventricular assist device (LVAD) condition at 37 degrees C. The KP101 achieved the LVAD conditions of 5 L/min and 100 mm Hg at 2,900 rpm; generated 10 L/min against 100 mm Hg at 3,200 rpm; 3 L/min against 90 mm Hg at 2,600 rpm; and 2 L/min against 80 mm Hg at 2,400 rpm. In addition, the pump efficiency during this experiment was 12.5%. The other Gyro pumps. that is, the C1E3, PI601, and PI701, in an LVAD condition require 1,600, 2,000, and 2,000 rpm, respectively. The KP101 produced a normalized index of hemolysis (NIH) value of 0.005 g/100 L. With regard to the NIH, the other Gyro pumps, namely the C1E3, PI601, and PI701 demonstrated 0.0007, 0.0028, and 0.004 g/100 L, respectively. The KP101 produced an acceptable pressure flow curve for a VAD. The NIH value was higher than that of other Gyro pumps, but is in an acceptable range.

  15. Permanent magnetic-levitation of rotating impeller: a decisive breakthrough in the centrifugal pump.

    PubMed

    Qian, K X; Zeng, P; Ru, W M; Yuan, H Y; Feng, Z G; Li, L

    2002-01-01

    Magnetic bearings have no mechanical contact between the rotor and stator, and a rotary pump with magnetic bearings therefore has no mechanical wear and thrombosis. The magnetic bearings available, however, contain electromagnets, are complicated to control and have high energy consumption. Therefore, it is difficult to apply an electromagnetic bearing to a rotary pump without disturbing its simplicity, reliability and ability to be implanted. The authors have developed a levitated impeller pump using only permanent magnets. The rotor is supported by permanent radial magnetic forces. The impeller is fixed on one side of the rotor; on the other side the rotor magnets are mounted. Opposite these rotor magents, a driving magnet is fastened to the motor axis. Thereafter, the motor drives the rotor via magnetic coupling. In laboratory tests with saline, where the rotor is still or rotates at under 4,000 rpm, the rotor magnets have one point in contact axially with a spacer between the rotor magnets and the driving magnets. The contacting point is located in the center of the rotor. As the rotating speed increases gradually to more than 4000 rpm, the rotor will disaffiliate from the stator axially, and become fully levitated. Since the axial levitation is produced by hydraulic force and the rotor magnets have a giro-effect, the rotor rotates very stably during levitation. As a left ventricular assist device, the pump works in a rotating speed range of 5,000-8,000 rpm, and the levitation of the impeller is assured by use of the pump. The permanent maglev impeller pump retains the advantages of the rotary pump but overcomes the disadvantages of the leviated pump with electromagnetic-bearing, and has met with most requirements of artificial heart blood pumps, thus promising to have more applications than previously.

  16. Performance simulation of a radial flow type impeller of centrifugal pumps using CFD

    NASA Astrophysics Data System (ADS)

    López, R.; Vaca, M.; Terres, H.; Lizardi, A.; Chávez, S.; García., M.

    2017-01-01

    The numerical simulation of a centrifugal impeller that had previously been designed and manufactured is presented in this paper. The following operating conditions were determined: 0.50 m3/min volumetric flow at a load of 25 m, velocity of rotation of 1750 rpm, and specific velocity of 0. 27. The ANSYS CFX 14.5 software with the k-ε turbulence model was used for simulation with appropriate boundary conditions. The distributions of velocities in the flow field in addition to the distribution of pressures on the entire impeller were obtained. The simulation showed no negative values for the pressure at the entrance of the impeller. The curve of hydrodynamic behaviour of the impeller, which contains the point of operation in which the pump will work was also developed.

  17. Underwater plasma-MIG arc welding: Shielding technique and pressure reduction by a centrifugal pump

    SciTech Connect

    Creutz, M.; Mewes, D.; Bartzsch, J.; Draugelates, U.

    1995-12-31

    In comparison to hyperbaric underwater welding in diving chambers, wet welding techniques promise higher flexibility and lower costs. One technique for creating a local dry and pressure reduced welding zone is the use of a centrifugal pump. Results of experimental investigations in combination with a plasma-MIG arc welding system are presented in this paper. Special importance is attached to the local pressure reduction in view of the fact that low pressure, i.e. a high pressure difference between surrounding water and dry welding area, is a good condition for welding but is difficult to be obtained with other shielding systems than pressure chambers. Plasma-MIG welding has been done under water with a good result on the weld quality. Values of the hardness of the joint and the appearance of the weld structure are nearly comparable to atmospheric welds.

  18. Hydrodynamic impeller stiffness, damping, and inertia in the rotordynamics of centrifugal flow pumps

    NASA Technical Reports Server (NTRS)

    Jery, S.; Acosta, A. J.; Brennen, C. E.; Caughey, T. K.

    1984-01-01

    The lateral hydrodynamic forces experienced by a centrifugal pump impeller performing circular whirl motions within several volute geometries were measured. The lateral forces were decomposed into: (1) time averaged lateral forces and (2) hydrodynamic force matrices representing the variation of the lateral forces with position of the impeller center. It is found that these force matrices essentially consist of equal diagonal terms and skew symmetric off diagonal terms. One consequence of this is that during its whirl motion the impeller experiences forces acting normal and tangential to the locus of whirl. Data on these normal and tangential forces are presented; it is shown that there exists a region of positive reduced whirl frequencies, within which the hydrodynamic forces can be destablizing with respect to whirl.

  19. Study on the influence of back blade shape on the wear characteristics of centrifugal slurry pump

    NASA Astrophysics Data System (ADS)

    Cai, X.; Zhou, S. P.; Li, S.

    2016-05-01

    CFX particle inhomogeneous model was introduced for the mechanism analysis of a centrifugal slurry pump which is equipped with back blades on impeller shrouds. Combining with the total efficiency correction, the simulation showed good prediction accuracy of external characteristics results compared with the experimental values. Vorticity and Q-Criterion were chosen as the variables to illustrate the abrasion morphology and wear mechanism by contrasting simulation result with worn impeller in engineering. The analysis showed that the large vorticity intensity areas are distributed at the edge of impeller shroud and intensively behind the back blades. Moreover, the vorticity scattered on suction surface of back blade shows the largest intensity. The contour of Q-Criterion demonstrated that the swirl scale in front cavity is obviously larger than that in back cavity. The distribution of vorticity on both front and back shrouds can reasonably explain the impeller wear characteristics. Finally, the forward curved back blade proved to be excellence performance in vorticity distribution.

  20. Experimental research on internal flow in impeller of a low specific speed centrifugal pump by PIV

    NASA Astrophysics Data System (ADS)

    Zhang, J. F.; Wang, Y. F.; Yuan, S. Q.

    2016-05-01

    For the purpose of investigating the influence of two different impellers, one is with splitter blades and the other one is without splitter blades, on a low-specific centrifugal pump. The experimental investigation in impellers was conducted at different conditions and phases by means of PIV (Particle Image Velocimetry) to study the internal flow. Meanwhile, the absolute and relative velocity distributions in impellers were obtained. Experimental results show that the head value is higher in the impeller with splitter blades and both two head curves appear hump phenomena at small flow rate. The absolute velocity value increases with radius and from pressure side to suction side at the same radius gradually. The splitter blades can scour the wake, making outlet velocity distribution more uniform and improving the internal flow. The velocity distribution becomes less even in the process of closing to tongue due to reinforced interference of tongue on internal flow.

  1. Annular Seals of High Energy Centrifugal Pumps: Presentation of Full Scale Measurement

    NASA Technical Reports Server (NTRS)

    Florjancic, S.; Stuerchler, R.; Mccloskey, T.

    1991-01-01

    Prediction of rotordynamic behavior for high energy concentration centrifugal pumps is a challenging task which still imposes considerable difficulties. While the mechanical modeling of the rotor is solved most satisfactorily by finite element techniques, accurate boundary conditions for arbitrary operating conditions are known for journal bearings only. Little information is available on the reactive forces of annular seals, such as neck ring and interstage seals and balance pistons, and on the impeller interaction forces. The present focus is to establish reliable boundary conditions at annular seals. For this purpose, a full scale test machine was set up and smooth and serrated seal configurations measured. Dimensionless coefficients are presented and compared with a state of the art theory.

  2. The optimization of low specific speed centrifugal pump based on incomplete sensitivities

    NASA Astrophysics Data System (ADS)

    Zhang, R. H.; Zheng, K.; Yao, L. H.; Shi, F. X.

    2012-11-01

    In this research, the optimization method for low specific speed centrifugal pump impeller based on incomplete sensitivities was proposed. The main feature of the algorithm is that it avoids solving the flow field repeatedly in one optimization cycle in finite difference method and it avoids solving the adjoint equation in adjoint method. The blade meridional plan is considered as constant, and the blade camber line was parameterize by Taylor function. The coefficients in the Taylor function were taken as the control variable. The moment acting on the blade was considered as the objective function. With the incomplete sensitivities we can get the gradient of the objective function with respect to the control variable easily, and the blade shape can be renewed according to the inverse direction of the gradient. We will find the optimum design when the objective function is minimized. The computational cost is greatly reduced. The calculation cases show that the proposed theory and method is rotational.

  3. On the inverse problem of blade design for centrifugal pumps and fans

    NASA Astrophysics Data System (ADS)

    Kruyt, N. P.; Westra, R. W.

    2014-06-01

    The inverse problem of blade design for centrifugal pumps and fans has been studied. The solution to this problem provides the geometry of rotor blades that realize specified performance characteristics, together with the corresponding flow field. Here a three-dimensional solution method is described in which the so-called meridional geometry is fixed and the distribution of the azimuthal angle at the three-dimensional blade surface is determined for blades of infinitesimal thickness. The developed formulation is based on potential-flow theory. Besides the blade impermeability condition at the pressure and suction side of the blades, an additional boundary condition at the blade surface is required in order to fix the unknown blade geometry. For this purpose the mean-swirl distribution is employed. The iterative numerical method is based on a three-dimensional finite element method approach in which the flow equations are solved on the domain determined by the latest estimate of the blade geometry, with the mean-swirl distribution boundary condition at the blade surface being enforced. The blade impermeability boundary condition is then used to find an improved estimate of the blade geometry. The robustness of the method is increased by specific techniques, such as spanwise-coupled solution of the discretized impermeability condition and the use of under-relaxation in adjusting the estimates of the blade geometry. Various examples are shown that demonstrate the effectiveness and robustness of the method in finding a solution for the blade geometry of different types of centrifugal pumps and fans. The influence of the employed mean-swirl distribution on the performance characteristics is also investigated.

  4. Numerical Investigation on Hydrodynamic Characteristics of a Centrifugal Pump with a Double Volute at Off-Design Conditions

    NASA Astrophysics Data System (ADS)

    Shim, H. S.; Kim, K. Y.

    2016-11-01

    Severe radial thrust under off-design operating conditions can be harmful factor for centrifugal pumps. In the present work, effects of geometry of a double volute casing on the hydrodynamic performance of a centrifugal pump have been investigated focusing on off-design conditions. Three-dimensional steady Reynolds-averaged Navier-Stokes analysis was carried out by using shear stress transport turbulence model. Numerical results for the hydrodynamic performance of the centrifugal pump were validated compared with experimental data. The hydraulic efficiency and radial thrust coefficient were used as performance parameters to evaluate the hydrodynamic characteristics of the centrifugal pump. The cross-sectional area ratio of the volute casing, the expansion coefficient of the rib structure, distance between the rib starting point and volute entrance, and radius of the volute entrance, were selected as geometric parameters. The results of parametric study show that performance parameters are significantly affected by both the geometric variables and operating conditions. Some configurations of the double volute casing showed outstanding performance in terms of the efficiency and radial thrust coefficient.

  5. Transient Stress- and Strain-Based Hemolysis Estimation in a Simplified Blood Pump

    PubMed Central

    Pauli, L.; Nam, J.; Pasquali, M.; Behr, M.

    2014-01-01

    SUMMARY We compare two approaches to numerical estimation of mechanical hemolysis in a simplified blood pump model. The stress-based model relies on the instantaneous shear stress in the blood flow, whereas the strain-based model uses an additional tensor equation to relate distortion of red blood cells to a shear stress measure. We use the newly proposed least-squares finite element method (LSFEM) to prevent negative concentration fields and show a stable and volume preserving LSFEM for the tensor equation. Application of both models to a simplified centrifugal blood pump at three different operating conditions show that the stress-based model overestimates the rate of hemolysis. The strain-based model is found to deliver lower hemolysis rates since it incorporates a more detailed description of biophysical phenomena into the simulation process. PMID:23922311

  6. Development of a pump flow estimator for rotary blood pumps to enhance monitoring of ventricular function.

    PubMed

    Granegger, Marcus; Moscato, Francesco; Casas, Fernando; Wieselthaler, Georg; Schima, Heinrich

    2012-08-01

    Estimation of instantaneous flow in rotary blood pumps (RBPs) is important for monitoring the interaction between heart and pump and eventually the ventricular function. Our group has reported an algorithm to derive ventricular contractility based on the maximum time derivative (dQ/dt(max) as a substitute for ventricular dP/dt(max) ) and pulsatility of measured flow signals. However, in RBPs used clinically, flow is estimated with a bandwidth too low to determine dQ/dt(max) in the case of improving heart function. The aim of this study was to develop a flow estimator for a centrifugal pump with bandwidth sufficient to provide noninvasive cardiac diagnostics. The new estimator is based on both static and dynamic properties of the brushless DC motor. An in vitro setup was employed to identify the performance of pump and motor up to 20 Hz. The algorithm was validated using physiological ventricular and arterial pressure waveforms in a mock loop which simulated different contractilities (dP/dt(max) 600 to 2300 mm Hg/s), pump speeds (2 to 4 krpm), and fluid viscosities (2 to 4 mPa·s). The mathematically estimated pump flow data were then compared to the datasets measured in the mock loop for different variable combinations (flow ranging from 2.5 to 7 L/min, pulsatility from 3.5 to 6 L/min, dQ/dt(max) from 15 to 60 L/min/s). Transfer function analysis showed that the developed algorithm could estimate the flow waveform with a bandwidth up to 15 Hz (±2 dB). The mean difference between the estimated and measured average flows was +0.06 ± 0.31 L/min and for the flow pulsatilities -0.27 ± 0.2 L/min. Detection of dQ/dt(max) was possible up to a dP/dt(max) level of 2300 mm Hg/s. In conclusion, a flow estimator with sufficient frequency bandwidth and accuracy to allow determination of changes in ventricular contractility even in the case of improving heart function was developed.

  7. Feasibility of the optical imaging of thrombus formation in a rotary blood pump by near-infrared light.

    PubMed

    Sakota, Daisuke; Murashige, Tomotaka; Kosaka, Ryo; Nishida, Masahiro; Maruyama, Osamu

    2014-09-01

    Blood coagulation is one of the primary concerns when using mechanical circulatory support devices such as blood pumps. Noninvasive detection and imaging of thrombus formation is useful not only for the development of more hemocompatible devices but also for the management of blood coagulation to avoid risk of infarction. The objective of this study is to investigate the use of near-infrared light for imaging of thrombus formation in a rotary blood pump. The optical properties of a thrombus at wavelengths ranging from 600 to 750 nm were analyzed using a hyperspectral imaging (HSI) system. A specially designed hydrodynamically levitated centrifugal blood pump with a visible bottom area was used. In vitro antithrombogenic testing was conducted five times with the pump using bovine whole blood in which the activated blood clotting time was adjusted to 200 s prior to the experiment. Two halogen lights were used for the light sources. The forward scattering through the pump and backward scattering on the pump bottom area were imaged using the HSI system. HSI showed an increase in forward scattering at wavelengths ranging from 670 to 750 nm in the location of thrombus formation. The time at which the thrombus began to form in the impeller rotating at 2780 rpm could be detected. The spectral difference between the whole blood and the thrombus was utilized to image thrombus formation. The results indicate the feasibility of dynamically detecting and imaging thrombus formation in a rotary blood pump.

  8. Blood Pump Having a Magnetically Suspended Rotor

    NASA Technical Reports Server (NTRS)

    Antaki, James F. (Inventor); Paden, Bradley (Inventor); Burgreen, Gregory (Inventor); Groom, Nelson J. (Inventor)

    2002-01-01

    A blood pump preferably has a magnetically suspended rotor that rotates within a housing. The rotor may rotate about a stator disposed within the housing. Radial magnetic bearings may be defined within the stator and the rotor in order to suspend the rotor. The radial magnetic bearings may be passive magnetic bearings that include permanent magnets disposed within the stator and the rotor or active magnetic bearings. The pump may further include an axial magnetic bearing that may be either a passive or an active magnetic bearing. A motor that drives the rotor may be disposed within the housing in order to more easily dissipate heat generated by the motor. A primary flow path is defined between the rotor and the stator, and a secondary flow path is defined between the stator and the rotor. Preferably, a substantial majority of blood passes through the primary flow path. The secondary flow path is large enough so that it provides adequate flushing of the secondary flow path while being small enough to permit efficient operation of the radial magnet bearings across the secondary flow path.

  9. Blood Pump Having a Magnetically Suspended Rotor

    NASA Technical Reports Server (NTRS)

    Antaki, James F. (Inventor); Paden, Bradley (Inventor); Burgreen, Gregory (Inventor); Groom, Nelson J. (Inventor)

    2001-01-01

    A blood pump preferably has a magnetically suspended rotor that rotates within a housing. The rotor may rotate about a stator disposed within the housing. Radial magnetic bearings may be defined within the stator and the rotor in order to suspend the rotor. The radial magnetic bearings may be passive magnetic bearings that include permanent magnets disposed within the stator and the rotor or active magnetic bearings. The pump may further include an axial magnetic bearing that may be either a passive or an active magnetic bearing. A motor that drives the rotor may be disposed within the housing in order to more easily dissipate heat generated by the motor. A primary flow path is defined between the rotor and the stator, and a secondary flow path is defined between the stator and the rotor. Preferably, a substantial majority of blood passes through the primary flow path. The secondary flow path is large enough so that it provides adequate flushing of the secondary flow path while being small enough to permit efficient operation of the radial magnet bearings across the secondary flow path.

  10. Dependence of the head of a centrifugal inclined Archimedean screw pump on the volume of cavitation cavities in the flow area of the pump

    NASA Astrophysics Data System (ADS)

    Grabovskaia, T. A.

    A comparison of theoretical and experimental results shows that the dependence of the head of a centrifugal inclined Archimedean screw pump on the volume of cavities in the flow area of the pump during oscillations is ambiguous and is determined by the effect of cavities in the flow area as well as by the head of the forepump. It is concluded that this finding should be taken into account in the calculation of unsteady processes for regimes with intense reverse flows at the inlet to the pump.

  11. Effects of outlet blade angle of centrifugal pump on the pump performance under air-water two-phase flow conditions

    SciTech Connect

    Minemura, Kiyoshi; Kinoshita, Katsuhiko; Ihara, Masaru; Furukawa, Hironori; Egashira, Kazuyuki

    1995-12-31

    To establish the optimum design parameters of offshore oil well centrifugal pumps, which should deliver crude oil containing a large amount of gas, various shapes of pump impeller with different outlet blade angles, locations of leading-edge and numbers of impeller blades as the design parameters were tested with various rotating speeds and suction pressures under air-water two-phase flow conditions. The greater the outlet blade angle, the less the degradation of the pump performance becomes, showing the optimum blade angle approximately equals to 90{degree}.

  12. Numerical research on the cavitation characteristics for typical conditions of a centrifugal pump with whole flow passage

    NASA Astrophysics Data System (ADS)

    Cao, L.; Wang, Z. W.; Xiao, Y. X.; Yao, Y. Y.; Zhu, W.

    2015-01-01

    Cavitation is one of the key issues affecting the safe and stable operation of centrifugal pumps. This research conducted numerical simulations of the 3-D turbulent flow in the whole flow passage of a centrifugal pump using RANS method. The calculation results of cavitation characteristics agreed well with the experimental results, which were based on SST k-ω turbulence model and Zwart-Gerber-Belamri cavitation model. This paper analysed the cavitation development process and the corresponding pump performance for three typical conditions, namely large discharge condition, design discharge condition and small discharge condition, by changing the available Net Positive Suction Head (NPSHa). For large discharge condition, the incipient NPSHa was large, while for design discharge condition and small discharge condition, the incipient NPSHa values were almost the same and both small. As the flow rate decreased, the critical NPSHa decreased as well, and the cavitation positons gradually shift from the pressure surfaces of some blades to the suction surfaces. At the same time, the tongue has greater effect with larger flow rate and the cavitation becomes less unsteady with the decrease of flow rate. With similar vapour volume, cavitation on the blade pressure side more easily leads to the drop of pump performance. Therefore, more attention should be paid to the cavitation characteristics of centrifugal pumps in large flow conditions in hydraulic design stage.

  13. Left ventricular assist device support with a centrifugal pump for 2 months in a 5-kg child.

    PubMed

    Inoue, Takafumi; Nishimura, Takashi; Murakami, Arata; Itatani, Keiichi; Takaoka, Tetsuhiro; Kitahori, Kazuo; Umeki, Akihide; Takezoe, Toshiko; Kashiwa, Koichi; Kyo, Shunei; Ono, Minoru

    2011-09-01

    The mid-term and long-term results of left ventricular assist device (LVAD) implantation for small children are still unsatisfactory. There have been few reports of LVAD implantation for more than a month in children weighing under 5 kg. We report the case of a 4-month-old female infant who survived for 2 months after being diagnosed with dilated cardiomyopathy (DCM) with extracorporeal centrifugal pump support. In recent years, although pumps designed for small children have been introduced and are used as a bridge to transplantation or recovery, mid-term or long-term mechanical support for small children with heart failure is still difficult. We managed to successfully provide support for a low-body-weight child with a centrifugal pump over a mid-term period. We achieved acceptable control of thrombosis, but eventually the infant died of sepsis. Autopsy revealed no prominent thrombosis in the perfusion cannula, drainage cannula, the pump, or the left ventricle. This is the first case report of LVAD support with the centrifugal pump, ROTAFLOW(®) (Maquet, Rastatt, Germany), for 2 months in a child weighing under 5 kg. Our method may potentially save severe heart failure children who need mid-term LVAD support.

  14. Left ventricular assist for pediatric patients with dilated cardiomyopathy using the Medos VAD cannula and a centrifugal pump.

    PubMed

    Huang, Shu-Chien; Chi, Nai-Hsin; Chen, Chun-An; Chen, Yih-Sharng; Chou, Nai-Kuan; Ko, Wen-Je; Wang, Shoei-Shen

    2009-11-01

    Ventricular assist devices for small pediatric patients are expensive and commercially unavailable in Taiwan. We used the Medos ventricular assist device cannula (Medos, Aachen, Germany) and a centrifugal pump to support pediatric patients with dilated cardiomyopathy and decompensated heart failure. From January 2007 to December 2008, three pediatric patients with dilated cardiomyopathy were supported using a centrifugal pump as the left ventricular assist device. The Medos arterial cannula was sutured to the ascending aorta, and the Apex cannula was fixed into the left ventricular apex. When the patient was weaned off of cardiopulmonary bypass, the left ventricular assist device pump was started. The pump flow was gradually titrated according to the filling status of the left ventricle. All the left ventricular assist devices were successfully implanted and functioned well. Two patients on extracorporeal membrane oxygenation had severe lung edema before left ventricular assist device implantation. Both patients required extracorporeal membrane oxygenation for the postoperative period until the pulmonary edema was resolved. Among the three patients, two successfully bridged to heart transplantation after support for 6 and 11 days, respectively. The first patient (10 kg) expired due to systemic emboli 30 days after left ventricular assist device support. In summary, these results suggest that the Medos ventricular assist device cannula and a centrifugal pump is an option for temporary left ventricular assist device support in patients with intractable heart failure and as a bridge to heart transplantation.

  15. Flow measurements in a model centrifugal pump by 3-D PIV

    NASA Astrophysics Data System (ADS)

    Yang, H.; Xu, H. R.; Liu, C.

    2012-11-01

    PIV (Particle Image Velocimetry), as an non-intrusive flow measurements technology, is widely used to investigate the flow fields in many areas. 3-D (three Dimensional) PIV has seldom been used to measure flow field in rotational impeller of centrifugal pump due to the difficulty of calibration in samll space. In this article, a specially manufactured water tank was used to perform the calibration for 3-D PIV measurement. The instantaneous absolute velocity in one impeller passage was obtained by merging of three sub zones and the relative velocity was acquired by velocity decomposition. The result shows that, when the pump runs at the condition of design flow rate, the radial component velocity Wr appears a concave distribution except the condition of R=45 mm. With the increase of radius, the circumference location of the minimum radial component velocity Wr moves from the pressure side to the suction side. At the same time, the tangential component velocity Wθ on the suction side decreases gradually with the increase of radius, while the component on the pressure side increases gradually. The secondary flow in different radius section has also been shown. At last, the error of PIV measurements was analyzed, which shows that the test results are accurate and the measured data is reliable.

  16. [A review of drive system for pulsatile blood pump].

    PubMed

    Han, Yuan-jie; Yang, Ming

    2009-01-01

    Many varieties of pulsatile blood pumps exist in the fields of artificial hearts and ventricular assist devices. Effective sorts can be achieved with the differences in power source and transmission mechanism. Horizontal comparison across different pulsatile blood pumps, together with evolution of similar species is studied to find the commonness and evolution laws for pulsatile blood pumps. After a review of typical pulsatile blood pumps from the angle of power source and transmission mechanism, much analysis is focus on a pulsatile drive structure with flexible electro-hydraulic transmission, and importance of hydraulic transmission to improve the implantation property of pulsatile blood pumps is discussed. Finally new application of electro-hydraulic pulsatile blood pumps in the future, such as the application in Direct Mechanical Ventricular Assistant Device (DMVAD) is given.

  17. A comparison study of haemolysis production in three contemporary centrifugal pumps.

    PubMed

    Bottrell, S; Bennett, M; Augustin, S; Thuys, C; Schultz, B; Horton, A; Horton, S

    2014-09-01

    One challenge in providing extracorporeal circulation is to supply optimal flow while minimising adverse effects, such as haemolysis. To determine if the recent generation constrained vortex pumps with their inherent design improvements would lead to reduced red cell trauma, we undertook a study comparing three devices. Utilizing a simulated short-term ventricular assist circuit primed with whole human blood, we examined changes in plasma free haemoglobin values over a six-day period. The three pumps investigated were the Maquet Rotaflow, the Levitronix PediVAS and the Medos Deltastream DP3.This study demonstrated that all three pumps produced low levels of haemolysis and are suitable for use in a clinical environment. The Levitronix PediVAS was significantly less haemolytic than either the Rotaflow (p<0.05) or the DP3 (p<0.05). There was no significant difference in plasma free haemoglobin between the Rotaflow and the DP3 (p=0.71).

  18. Axial reciprocation of rotating impeller: a new concept of antithrombogenecity in centrifugal pump.

    PubMed

    Qian, K X; Zeng, P; Ru, W M; Yuan, H Y; Feng, Z G; Li, L

    2001-01-01

    For long-term application, rotary pumps have to solve the problems of bearing wear and thrombosis along the bearing. Most investigators choose the magnetic bearing to realize zero-friction and no contact between the rotor and stator; the former avoids the mechanical wear and the latter eliminates the possibility of thrombus formation. The authors have tried and found, however, that it is difficult to apply a magnetic bearing to the rotary pump without disturbing its simplicity, reliability and implantability, and have therefor developed a much simpler and much more creative approach to achieve the same results. Instead of using a sliding bearing, a rolling bearing has been devised for the pump, and its friction is about 1/15 of the sliding bearing. Furthermore, a wear-proof material of ultra-high-molecular weight polythene has been adopted to make the rollers, and its anti-wear property is 8 times better than metal. Thereby, the service life of the bearing has been prolonged to ten years according to the documents provided by the producer. In order to prevent the thrombus formation along the bearing, the impeller reciprocates axiallly as the impeller changes its rotating speed periodically to produce a pulsatile flow. The reciprocation is the result of the effects of a magnetic force between the motor rotor and stator, and a hydraulic force between the blood flow and the impeller. Similar to a piston pump, the oscillating impeller can make the blood flow in and out of the bearing, resulting in wash-out once a circle. This obviously helps to prevent thombosis along the bearing and in the pump. The endurance tests with saline of this novel pump demonstrated the durabililty of the device. It promises to be able to assist the circulation of patients permanently, and to be able to replace heart transplantation in the future.

  19. An experimental and analytical investigation into the performance of centrifugal pumps operating with air-water mixtures

    NASA Astrophysics Data System (ADS)

    Sterrett, John Douglas

    1994-01-01

    An investigation was made into the performance of centrifugal pumps when two-phase non-condensable mixtures of gas and liquid are flowing. This problem is encountered during loss-of-coolant accidents in nuclear reactor systems and in the pumping of oil where natural gas may be present in the mixture. Analytical and experimental techniques were used to address the issues of scaling between a model and a prototype pump and the validity of the single-phase pump affinity laws when two-phase flows are present. The results from this effort have also provided insight into the physical phenomena which cause the degradation in pump performance. An analytical model for the motion of a single bubble through a pump impeller is provided. The results from this fundamental problem show that the Coriolis and buoyancy forces are important in describing the kinematics of a gas phase. These results show that dynamic similitude is not preserved between a model and prototype impeller when the standard single-phase pump scaling relationships are used. The motion of a single bubble is also shown to be influenced by the magnitude of the pump suction pressure. The results from an extensive series of air-water two phase pump tests are provided. A 1/4 scale pump, modeled after the Savannah River Site K-reactor pumps, was tested over a wide range of pump speeds, flow rates, and suction pressures. These results indicate that the single-phase pump affinity laws are not applicable to two-phase pump flows and that the magnitude of the pump suction pressure is an important quantity in determining the pump performance. A second analytical model is developed for two-phase flow through a pump impeller. The results from this one-dimensional, two-fluid, non-homogeneous streamline model show good agreement with the experimental data. The model results support the experimental data in showing that the single-phase pump affinity relationships are not valid for two-phase pump flows and that dynamic

  20. Axial reciprocation of rotating impeller: a novel approach to preventing thrombosis in centrifugal pump.

    PubMed

    Qian, K X; Zeng, P; Ru, W M; Yuan, H Y

    2002-01-01

    For long-term application, rotary pumps have to solve the problems of bearing wear and thrombosis along the bearing. Some investigators choose the magnetic bearing for zero friction and to provide no contact between the rotor and stator; the former avoids the mechanical wear and the latter eliminates the possibility of thrombus formation. The authors have tried and have found, however, that it is difficult to apply a magnetic bearing to the rotary pump without disturbing its simplicity, reliability, and implantability, and have therefore developed a much simpler approach to achieve the same results. Instead of using a sliding bearing, a rolling bearing has been devised, and its friction is about 1/15 that of the sliding bearing. Furthermore, a wearproof material of ultra high molecular weight polythene has been adopted to make the rollers, and its antiwear property is eight times better than metal. The service life of the bearing has thus been prolonged. To prevent thrombus formation along the bearing, the impeller reciprocates axially as the impeller changes its rotating speed periodically to produce a pulsatile flow. The reciprocation is the result of the effects of a magnetic force between the motor rotor and stator and a hydraulic force between the blood flow and the impeller. Similar to a piston pump, the oscillating impeller can make the blood flow in and out of the bearing, resulting in washout with fresh blood once a cycle. This obviously helps to prevent thrombosis along the bearing and in the pump. Endurance tests with saline of this novel pump demonstrated device durability, promising long-term assisted circulation.

  1. Numerical research on the effects of impeller pump-out vanes on axial force in a solid-liquid screw centrifugal pump

    NASA Astrophysics Data System (ADS)

    Cheng, X. R.; Li, R. N.; Gao, Y.; Guo, W. L.

    2013-12-01

    A commercial CFD code has been used to predict the performance of a screw centrifugal pump with pump-out vanes, especially when changing regularity of impeller axial force based on the solid-liquid two-phase flow. The Unsteady Reynolds Averaged Navier-Stokes (URANS) approach has been applied to solve the unsteady, incompressible, three-dimensional turbulent. The SIMPLEC algorithm, standard wall functions and mix two-phase flow model were applied. The RNG k ε-model was used to account the turbulence effects. By changing the number of impeller pump-out vanes and width, six different screw centrifugal pump numerical simulation projects were given, and each scheme in the different solid volume fraction were calculated respectively. The change rules of axial force, velocity and pressure distribution of flow field were obtained on the different condition and different volume fraction. The results showed that the axial forces values based solid-fluid two-phase greater than based single-phase clear water, but both changing regularity of the axial force were consistent; as same condition, the same solid-phase volume concentration, with the increase of pump-out vanes number or width, the impeller axial force increased as well. Meanwhile the number of the pump-out vanes and the width of pump-out vanes in balancing the impeller axial force, there are the most optimal value.

  2. Left heart bypass support with the Rotaflow Centrifugal Pump® as a bridge to decision and recovery in an adult.

    PubMed

    Kashiwa, Koichi; Nishimura, Takashi; Saito, Aya; Kubo, Hitoshi; Fukaya, Aoi; Tamai, Hisayoshi; Yambe, Tomoyuki; Kyo, Shunei; Ono, Minoru

    2012-06-01

    Since left heart bypass or biventricular circulatory assist with an extracorporeal centrifugal pump as a bridge to decision or recovery sometimes requires long-time support, the long-term durability of extracorporeal centrifugal pumps is crucial. The Rotaflow Centrifugal Pump(®) (MAQUET Cardiopulmonary AG, Hirrlingen, Germany) is one of the centrifugal pumps available for long-term use in Japan. However, there have been few reports of left heart bypass or biventricular circulatory support over the mid-term. This is a case report of left heart bypass support with the Rotaflow Centrifugal Pump(®) as a bridge to decision and recovery for an adult patient who could not be weaned from cardiopulmonary bypass and percutaneous cardiopulmonary support after cardiac surgery. We could confirm that the patient's consciousness level was normal; however, the patient could not be weaned from the left heart bypass support lasting 1 month. Therefore, the circulatory assist device was switched to the extracorporeal Nipro ventricular assist device (VAD). This time, left heart bypass support could be maintained for 30 days using a single Rotaflow Centrifugal Pump(®). There were no signs of hemolysis during left heart bypass support. The Rotaflow Centrifugal Pump(®) itself may be used as a device for a bridge to decision or recovery before using a VAD in cardiogenic shock patients.

  3. Assessment of hydraulic performance and biocompatibility of a MagLev centrifugal pump system designed for pediatric cardiac or cardiopulmonary support.

    PubMed

    Dasse, Kurt A; Gellman, Barry; Kameneva, Marina V; Woolley, Joshua R; Johnson, Carl A; Gempp, Thomas; Marks, John D; Kent, Stella; Koert, Andrew; Richardson, J Scott; Franklin, Steve; Snyder, Trevor A; Wearden, Peter; Wagner, William R; Gilbert, Richard J; Borovetz, Harvey S

    2007-01-01

    The treatment of children with life-threatening cardiac and cardiopulmonary failure is a large and underappreciated public health concern. We have previously shown that the CentriMag is a magnetically levitated centrifugal pump system, having the utility for treating adults and large children (1,500 utilized worldwide). We present here the PediVAS, a pump system whose design was modified from the CentriMag to meet the physiological requirements of young pediatric and neonatal patients. The PediVAS is comprised of a single-use centrifugal blood pump, reusable motor, and console, and is suitable for right ventricular assist device (RVAD), left ventricular assist device (LVAD), biventricular assist device (BVAD), or extracorporeal membrane oxygenator (ECMO) applications. It is designed to operate without bearings, seals and valves, and without regions of blood stasis, friction, or wear. The PediVAS pump is compatible with the CentriMag hardware, although the priming volume was reduced from 31 to 14 ml, and the port size reduced from 3/8 to (1/4) in. For the expected range of pediatric flow (0.3-3.0 L/min), the PediVAS exhibited superior hydraulic efficiency compared with the CentriMag. The PediVAS was evaluated in 14 pediatric animals for up to 30 days, demonstrating acceptable hydraulic function and hemocompatibility. The current results substantiate the performance and biocompatibility of the PediVAS cardiac assist system and are likely to support initiation of a US clinical trial in the future.

  4. Effects of radial diffuser hydraulic design on a double-suction centrifugal pump

    NASA Astrophysics Data System (ADS)

    Hou, H. C.; Zhang, Y. X.; Xu, C.; Zhang, J. Y.; Li, Z. L.

    2016-05-01

    device and is good to transform the dynamic energy to pressure energy. Then through the hydraulic loss analysis of each pump component for all diffusers, it shows that the impeller takes up the biggest part of the whole loss about 8.19% averagely, the radial diffuser about 3.70% and the volute about 1.65%. The hydraulic loss of impeller is dominant at the large flow rate while the radial diffuser is at the small flow rate. Among all diffusers, the ES profile diffuser generates the least loss and combined to the distribution of velocity vector and turbulent kinetic energy for two kinds of diffusers it also shows that ES profile is fit to apply in radial diffuser. This research can offer a significant reference for the radial diffuser hydraulic design of such centrifugal pumps.

  5. Studies of the impact of prerotation problem of the secondary impeller on performance of multi-stage centrifugal pumps

    NASA Astrophysics Data System (ADS)

    Zhai, L. L.; Wu, P.; Jiang, Q. L.; Wang, L. Q.

    2012-11-01

    In engineering practice, part of the multi-stage centrifugal pumps is designed without space guide vanes due to the size restrictions and the volute is distorted much in shape. In these pumps, tangential velocity of the fluid at the outlet of the first-stage impeller is so great that it has caused a prerotation problem which will affect the inlet flow conditions of the secondary impeller leading to serious efficiency and head decline of the secondary impeller. The head problem of the second stage in multi-stage centrifugal pumps caused by prerotation at the entrance of the second stage was analyzed and the internal hydraulic performance was optimized by setting clapboards in the volute in this paper. CFD numerical simulation method combined with experiment was applied to predict the effect of internal clapboards on the performance of the centrifugal pump. The original prototype was transformed according to the simulation result and tested to verify the optimization work. The experiment result shows that hydraulic performance is remarkably improved compared with the original one and the prerotation problem is basically solved.

  6. Hemolysis during cardiac extracorporeal membrane oxygenation: a case-control comparison of roller pumps and centrifugal pumps in a pediatric population.

    PubMed

    Byrnes, Jonathan; McKamie, Wes; Swearingen, Christopher; Prodhan, Parthak; Bhutta, Adnan; Jaquiss, Robert; Imamura, Michiaki; Fiser, Richard

    2011-01-01

    Extracorporeal membrane oxygenation (ECMO) is a lifesaving therapy, which has been used for the support of children with a broad range of diseases. Two pumps of differing mechanisms have been used to generate the extracorporeal flow: roller-head pumps and centrifugal pumps. Seven patients supported during ECMO with Levitronix Centrimag (Centrimag group [CG]) were matched to 14 patients supported with Stockert-Shiley SIII (Stockert-Shiley group [SSG]) at a single institution from July 2007 to July 2009. We hypothesized that hemolysis as measured by plasma-free hemoglobin (PFH) is elevated in the SSG versus the CG during cardiac ECMO. Categorical data were analyzed using Fisher's exact test. Plasma-free hemoglobin differences between groups were analyzed using both Wilcoxon rank sum and beta regression. Overall, SSG patients had two times the odds of having a higher PFH than CG patients adjusting for repeated measures (odds ratio [OR] = 1.96, 95% confidence interval [CI]: [1.15-3.34], p < 0.014). Differences between circuit failure in the first 168 hours did not reach statistical significance (1/7 CG vs. 7/14 SSG; p = 0.174). In this population of cardiac patients requiring ECMO support, more hemolysis occurred in the SSG, a roller-head pump supported group, when compared with the CG, a centrifugal pump supported group. Differences in circuit life did not reach statistical significance. This pilot study contrasts with past studies, which have demonstrated more hemolysis occurring with centrifugal pumps when compared with roller-head pumps.

  7. A teaspoon pump for pumping blood with high hydraulic efficiency and low hemolysis potential.

    PubMed

    Dame, D

    1996-06-01

    Virtually all blood pumps contain some kind of rubbing, sliding, closely moving machinery surfaces that are exposed to the blood being pumped. These valves, internal bearings, magnetic bearing position sensors, and shaft seals cause most of the problems with blood pumps. The original teaspoon pump design prevented the rubbing, sliding machinery surfaces from contacting the blood. However, the hydraulic efficiency was low because the blood was able to "slip around" the rotating impeller so that the blood itself never rotated fast enough to develop adequate pressure. An improved teaspoon blood pump has been designed and tested and has shown acceptable hydraulic performance and low hemolysis potential. The new pump uses a nonrotating "swinging" hose as the pump impeller. The fluid enters the pump through the center of the swinging hose; therefore, there can be no fluid slip between the revolving blood and the revolving impeller. The new pump uses an impeller that is comparable to a flexible garden hose. If the free end of the hose were swung around in a circle like half of a jump rope, the fluid inside the hose would rotate and develop pressure even though the hose impeller itself did not "rotate"; therefore, no rotating shaft seal or internal bearings are required.

  8. Miniaturization of a magnetically levitated axial flow blood pump.

    PubMed

    Cheng, Shanbao; Olles, Mark W; Olsen, Don B; Joyce, Lyle D; Day, Steven W

    2010-10-01

    This article introduces a unique miniaturization process of a magnetically levitated axial flow blood pump from a functional prototype to a pump suitable for animal trials. Through COMSOL three-dimensional finite element analysis and experimental verification, the hybrid magnetic bearings of the pump have been miniaturized, the axial spacing between magnetic components has been reduced, and excess material in mechanical components of the pump was reduced. Experimental results show that the pump performance was virtually unchanged and the smaller size resulted in the successful acute pump implantation in calves.

  9. Implantation of the VentrAssist Implantable Rotary Blood Pump in sheep.

    PubMed

    James, Natalie L; van der Meer, Anita L; Edwards, Glenn A; Snelling, Samuel R; Begg, John D; Esmore, Donald S; Woodard, John C

    2003-01-01

    The VentrAssist Implantable Rotary Blood Pump (IRBP) is a hydrodynamically suspended, electromagnetically driven, centrifugal blood pump that provides continuous flow of up to 10 L/min at 3,000 rpm. In vivo studies in sheep were conducted to assess system design and performance. Surgery involved thoracotomy with subdiaphragmatic pump placement. Cannulae were transdiaphragmatic, with inflow in the left ventricular apex and outflow anastomosed to the descending aorta. Animals had no anticoagulation or antiplatelet therapy after surgery and no prophylactic antibiotics after recovery. Twelve sheep were supported for 622 pump days. Estimated pump flow ranged from 1 to 5.5 L/min at 1,800 to 2,000 rpm using 2.5 to 4.5 W. There was no clinical evidence of hemolysis or cardiovascular, renal, or hepatic dysfunction. Adverse outcomes included kinking/disconnection of the outflow cannula caused by the graft bend relief (n = 4), which was addressed through cannula redesign. Pump electrical malfunction (n = 4), caused by a silicone potting compound, was corrected using a neutral curing potting material. Surgical/husbandry issues (n = 2) also were addressed. The VentrAssist IRBP provides high flow at low rotational speed and power consumption. Further trials are in progress in advance of in vivo studies of the safety and efficacy of the final system.

  10. Injury in organs after cardiopulmonary bypass: a comparative experimental morphological study between a centrifugal and a new pulsatile pump.

    PubMed

    Herreros, Jesús; Berjano, Enrique J; Sola, Josu; Vlaanderen, Wouter; Sales-Nebot, Laura; Más, Pedro; Padrós, Clemente; Díaz, Pedro; Rábago, Gregorio; Mercé, Salvador

    2004-08-01

    The aim of this investigation was to assess organ injury provoked by a new pulsatile pump for cardiopulmonary bypass (CPB) with respect to a conventional centrifugal pump. Eight pigs in the pulsatile group (PG) and five in the centrifugal group (CG) underwent a partial CPB lasting 180 min. The animals were sacrificed 180 min after CPB was suspended, and a morphological study of fragments of ventricular wall, liver, lung, and kidney was performed. In CG, centrilobular hepatic necrosis was observed accompanied by sinusoidal dilatation and congestion, multiple focuses of myocardial ischemia, and minor to moderate pulmonary interstitial edema. In PG, diffuse centrilobular sinusoidal congestion in the liver, congestion and capillary dilatation of low intensity in the ventricular wall, and nonsignificant pulmonary interstitial septal edema was observed. In the kidney, both groups showed degenerative changes of the tubular cells and nonsignificant tubular dilatation. These results suggest a better peripheral circulation in the pulsatile group.

  11. Analysis and modeling of flow in rotating spiral microchannels: towards math-aided design of microfluidic systems using centrifugal pumping.

    PubMed

    Wang, Lin; Kropinski, Mary-Catherine; Li, Paul C H

    2011-06-21

    This paper describes the experimental measurement and mathematical modeling of centrifugally-pumped flow in spiral microchannels. Here, the liquid is delivered by the rotation of a circular microchip as depicted before (X. Y. Peng, P. C. H. Li, H. Z. Yu, M. Parameswaran and W. L. Chou, Sens. Actuators, B, 2007, 128, 64-69). The spiral microchannel in it was specially designed to produce a constant centrifugal force component. From experimental measurements, it was found that the flow velocity inside the spiral microchannels was associated with the rotation speed only, but not with the length of the liquid column. The mathematical modeling of liquid flow was constructed based on solving the Navier-Stokes equations of incompressible flow formulated in a new orthogonal curvilinear coordinate system aligned with the channel geometry. The governing equations were simplified under various assumptions, rendering a mathematically-tractable physical model. In addition, a commercial computational fluid dynamics (CFD) program was used to simulate the flow in the spiral microchannel. The predicted liquid flow velocities from the mathematical model and the CFD program showed reasonable agreement with the experimental data. Under proper assumptions, the mathematical model gave a flexible and rather accurate analytical solution using much less computing power. The proposed study demonstrated the effectiveness of the spiral microchannel design in microfluidic applications using centrifugal force. With modifications, this study could be adapted to the simulation and modeling of other centrifugal-pumping microflow systems.

  12. Analysis of the effect of hydrophobic properties of surfaces in the flow part of centrifugal pumps on their operational performance

    NASA Astrophysics Data System (ADS)

    Volkov, A. V.; Parygin, A. G.; Lukin, M. V.; Ryzhenkov, A. V.; Khovanov, G. P.; Naumov, A. V.; Soukal, J.; Pochyly, F.; Fialova, S.

    2015-11-01

    The results of experimental studies focused on evaluating the effect of different conditions of wetting of functional surfaces in flow parts of centrifugal pumps (specifically, impellers) used in heat- and watersupply systems on their operational performance are presented. The conditions of interaction of the pumped medium with the impeller surfaces were altered through hydrophobization of functional surfaces that was implemented using the techniques developed at the Moscow Power Engineering Institute and the Brno University of Technology. It is demonstrated that this hydrophobization produced a considerable positive effect and raised the efficiency of pump units based on centrifugal KM pumps of three different form factors produced by ZAO Pompa (Shchelkovo) and a K centrifugal pump produced by Sigma. The efficiency was increased by 2-6% depending on the pump model. The results of experimental studies of the effect of hydrophobization of the surface of a canonical plate-type domain with a working medium flowing longitudinally along it in a hydrodynamic bed (Moscow Power Engineering Institute) are detailed. Two flat plates with a length of 250 mm and a width of 252 mm were studied. The surfaces of these plates had different roughness values, since one of the plates was polished prior to hydrophobization. Different wetting conditions, which were monitored by measuring the contact angle with a KRUSS MobileDrop goniometer, were established after hydrophobization. The obtained experimental data showed that the surface friction of the modified plate with a higher initial roughness (unpolished plate) was reduced by as much as 23%. This result agrees completely with the Cassie hypothesis.

  13. A microfluidic timer for timed valving and pumping in centrifugal microfluidics.

    PubMed

    Schwemmer, F; Zehnle, S; Mark, D; von Stetten, F; Zengerle, R; Paust, N

    2015-03-21

    Accurate timing of microfluidic operations is essential for the automation of complex laboratory workflows, in particular for the supply of sample and reagents. Here we present a new unit operation for timed valving and pumping in centrifugal microfluidics. It is based on temporary storage of pneumatic energy and time delayed sudden release of said energy. The timer is loaded at a relatively higher spinning frequency. The countdown is started by reducing to a relatively lower release frequency, at which the timer is released after a pre-defined delay time. We demonstrate timing for 1) the sequential release of 4 liquids at times of 2.7 s ± 0.2 s, 14.0 s ± 0.5 s, 43.4 s ± 1.0 s and 133.8 s ± 2.3 s, 2) timed valving of typical assay reagents (contact angles 36-78°, viscosities 0.9-5.6 mPa s) and 3) on demand valving of liquids from 4 inlet chambers in any user defined sequence controlled by the spinning protocol. The microfluidic timer is compatible to all wetting properties and viscosities of common assay reagents and does neither require assistive equipment, nor coatings. It can be monolithically integrated into a microfluidic test carrier and is compatible to scalable fabrication technologies such as thermoforming or injection molding.

  14. Multicondition Optimization and Experimental Measurements of a Double-Blade Centrifugal Pump Impeller.

    PubMed

    Liu, Houlin; Wang, Kai; Yuan, Shouqi; Tan, Minggao; Wang, Yong; Dong, Liang

    2013-01-01

    In order to improve internal unsteady flow in a double-blade centrifugal pump (DBCP), this study used major geometric parameters of the original design as the initial values, heads at three conditions (i.e., 80% design flow rate, 100% design flow rate, and 120% design flow rate) as the constraints conditions, and the maximum of weighted average efficiency at the three conditions as the objective function. An adaptive simulated annealing algorithm was selected to solve the energy performance calculation model and the supertransitive approximation method was applied to fix optimal weight factors of individual objectives. On the basis of hydraulic performance optimization, three-condition automatic computational fluid dynamics (CFD) optimization of impeller meridional plane for the DBCP was realized by means of Isight software integrated Pro/E, Gambit, and Fluent software. The shroud arc radii R0 and R1, shroud angle T1, hub arc radius R2, and hub angle T2 on the meridional plane were selected as the design variables and the maximum of weighted average hydraulic efficiency at the three conditions was chosen as the objective function. Performance characteristic test and particle image velocimetry (PIV) measurements of internal flow in the DBCP were conducted. Performance characteristic test results show that the weighted average efficiency of the impeller after the three-condition optimization has increased by 1.46% than that of original design. PIV measurements results show that vortex or recirculation phenomena in the impeller are distinctly improved under the three conditions.

  15. Measurement on the Fluid Forces Induced by Rotor-Stator Interaction in a Centrifugal Pump

    NASA Astrophysics Data System (ADS)

    Guo, Shijie; Okamoto, Hidenobu; Maruta, Yoshiyuki

    The pressure fluctuations and the radial fluid forces induced by rotor-stator interaction in a centrifugal pump were measured and their relationship was investigated. Experiments were done for various guide vanes, flow rates, and rotating speeds. It was demonstrated that both the blade pressure fluctuations and the volute static pressures are non-uniform circumferentially (not axisymmetric) under off-design operating conditions and that the two have a strong relationship. At high flow rates, the interaction-induced blade pressure fluctuations are large in areas where the volute static pressure is low. The propagating directions of the pressure fluctuations, the whirling directions of the radial fluid forces acting on the impeller and the dominant frequency components of both the fluctuations and the fluid forces are discussed. When measuring the fluid forces in the rotating frame, other frequency components, in addition to those related to the products of the number of guide vanes and the rotating frequency, may occur due to the circumferential unevenness of the pressure fluctuations.

  16. Numerical study of unsteady flows with cavitation in a high-speed micro centrifugal pump

    NASA Astrophysics Data System (ADS)

    Li, Yeqiang; Yuan, Shiwei; Lai, Huanxin

    2017-02-01

    The unsteady flows caused by the interaction between the impeller and the volute in a high-speed micro centrifugal pump are numerically studied. The internal flows of both with and without cavitations are analyzed using the CFX. The characteristics of unsteady pressure on the blade surfaces and the symmetric plane of the volute are presented and compared. The results show that the amplitudes of pressure fluctuations of critical cavitation on the blade pressure surface (PS) are bigger as compared with those at the non-cavitation condition, but on the suction surface (SS), the situation is on the contrary. When cavitation occurs, reduction of load in the impeller is a result. In the present study, such reduction of load is observed mainly on the first half of the blades. Pressure fluctuations at five monitoring points, denoted by WK1 to WK5 in the volute, are also analyzed. No matter at the critical cavitation or at the non-cavitation conditions, the monitored pressure fluctuations are at the same frequencies, which equal to the blade passing frequency (BPF) and its multiples. However, the amplitudes of the fluctuations at critical cavitation condition are considerably stronger, as compared with those for without cavitation.

  17. Does an Open Recirculation Line Affect the Flow Rate and Pressure in a Neonatal Extracorporeal Life Support Circuit With a Centrifugal or Roller Pump?

    PubMed

    Wang, Shigang; Spencer, Shannon B; Woitas, Karl; Glass, Kristen; Kunselman, Allen R; Ündar, Akif

    2017-01-01

    The objective of this study is to evaluate the impact of an open or closed recirculation line on flow rate, circuit pressure, and hemodynamic energy transmission in simulated neonatal extracorporeal life support (ECLS) systems. The two neonatal ECLS circuits consisted of a Maquet HL20 roller pump (RP group) or a RotaFlow centrifugal pump (CP group), Quadrox-iD Pediatric oxygenator, and Biomedicus arterial and venous cannulae (8 Fr and 10 Fr) primed with lactated Ringer's solution and packed red blood cells (hematocrit 35%). Trials were conducted at flow rates ranging from 200 to 600 mL/min (200 mL/min increments) with a closed or open recirculation line at 36°C. Real-time pressure and flow data were recorded using a custom-based data acquisition system. In the RP group, the preoxygenator flow did not change when the recirculation line was open while the prearterial cannula flow decreased by 15.7-20.0% (P < 0.01). Circuit pressure, total circuit pressure drop, and hemodynamic energy delivered to patients also decreased (P < 0.01). In the CP group, the prearterial cannula flow did not change while preoxygenator flow increased by 13.6-18.8% (P < 0.01). Circuit pressure drop and hemodynamic energy transmission remained the same. The results showed that the shunt of an open recirculation line could decrease perfusion flow in patients in the ECLS circuit using a roller pump, but did not change perfusion flow in the circuit using a centrifugal pump. An additional flow sensor is needed to monitor perfusion flow in patients if any shunts exist in the ECLS circuit.

  18. Magnetically suspended rotary blood pump with radial type combined motor-bearing.

    PubMed

    Masuzawa, T; Kita, T; Matsuda, K; Okada, Y

    2000-06-01

    A magnetically suspended centrifugal blood pump is being developed with a combined motor-bearing for long-term ventricular assist systems. The combined motor-bearing actively suspends a rotor in a radial direction to deal with radial force unbalance in the pump and rotates the rotor by using the electric magnetic field. Therefore, the pump has no mechanical parts such as bearings of the motor and has a long lifetime. The developed pump consists of a thin rotor with a semi open-type 6 vane impeller and a stator to suspend and rotate the rotor. The rotor has 4-pole permanent magnets on the circumferential surface. The outer diameter and the thickness of the rotor are 60 mm and 8 mm, respectively. Axial movement and tilt of the rotor are restricted by passive stability based on the thin rotor structure. Radial movements of the rotor, such as levitation in radial direction and rotation, are controlled actively by using electric magnets of the stator. The electric magnet coils to produce levitation and rotation forces are constructed on the periphery stator. The p +/- 2-pole algorithm and the synchronous motor mechanism are adopted to levitate and rotate the rotor. The radial gap between the rotor and the stator is 1 mm. A closed-loop circuit filled with water was connected to the developed pump to examine the basic performance of the pump and the magnetic suspension system. Maximum rotational speed, flow rate, and head were 2,800 rpm, 11 L/min, and 270 mm Hg, respectively. The rotor with the impeller could be suspended completely during the entire pumping process. We conclude the pump with the combined motor-bearing has sufficient performance for the blood pump.

  19. Development of a miniature intraventricular axial flow blood pump.

    PubMed

    Yamazaki, K; Umezu, M; Koyanagi, H; Outa, E; Ogino, S; Otake, Y; Shiozaki, H; Fujimoto, T; Tagusari, O; Kitamura, M

    1993-01-01

    A new intraventricular axial flow blood pump has been designed and developed as a totally implantable left ventricular assist device (LVAD). This pump consists of an impeller combined with a guide-vane, a tube housing, and a DC motor. The pump is introduced into the LV cavity through the LV apex, and the outlet cannula is passed antegrade across the aortic valve. Blood is withdrawn from the LV through the inlet ports at the pump base, and discharged to the ascending aorta. Our newly developed axial flow pump system has the following advantages: 1) it is a simple and compact system, 2) minimal blood stasis both in the device and the LV cavity, 3) minimal blood contacting surface of the pump, 4) easy accessibility with a less invasive surgical procedure, and 5) low cost. A pump flow > 5 L/min was obtained against 100 mmHg differential pressure in the mock circulatory system. The pump could produce a passive pulsatile flow effect with a beating heart more efficiently than other non-pulsatile pumps because of minimal pressure drop and inertia along the bypass tract. Anatomic fit studies using dissected hearts of dilated cardiomyopathy (DCM) cadavers showed that this pump could smoothly pass through the aortic valve without any interference with mitral valve function. Recently, a dynamic pressure groove bearing and a miniature lip seal have been developed. The dynamic pressure groove bearing has a simple structure and acts as a pressure resistant sealing mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

  20. Comparison of the centrifugal and roller pump in elective coronary artery bypass surgery--a prospective, randomized study with special emphasis upon platelet activation.

    PubMed

    Andersen, Knut S; Nygreen, Else L; Grong, Ketil; Leirvaag, Beryl; Holmsen, Holm

    2003-12-01

    Objective--Evaluation of the centrifugal pump vs roller pump concerning effects upon platelet function, hemolysis and clinical outcome in elective coronary artery bypass surgery. Design--Thirty-four patients were randomized to centrifugal or roller pump. Platelet activation was studied by flow cytometry before, during and up to 3 days after bypass. Results--Duration of bypass, ischemic period, peripheral anastomoses, hospital stay and mortality did not differ. In roller pump patients, platelet aggregates increased by 250% between end of bypass and 3 h postoperatively (p < 0.001). A secondary, fivefold increase in number of platelet aggregates was found on the 3rd postoperative day (p < 0.001). In the centrifugal pump group, these changes were not significant. Hemolysis increased (20%) at end of bypass and 3 h postoperatively (p < 0.005), and decreased to preoperative levels the next day without group difference. Conclusion--Platelet aggregation was significantly increased in roller compared with centrifugal pump patients, indicating higher susceptibility to postoperative thrombotic complications with the roller pump. Otherwise, there was no clinical evidence for superiority of the centrifugal pump.

  1. Noninvasive miniaturized mass-flow meter using a curved cannula for implantable axial flow blood pump.

    PubMed

    Kosaka, Ryo; Nishida, Masahiro; Maruyama, Osamu; Yamane, Takashi

    2011-01-01

    Blood flow should be measured to monitor conditions of patients with implantable artificial hearts continuously and noninvasively. We have developed a noninvasive miniaturized mass-flow meter using a curved cannula for an axial flow blood pump. The mass-flow meter utilized centrifugal force generated by the mass-flow rate in the curved cannula. Two strain gauges served as sensors. Based on the numerical analysis, the first gauge, attached to the curved area, measured static pressure and centrifugal force, and the second, attached to the straight area, measured static pressure for static pressure compensation. The mass-flow rate was determined by the differences in output from the two gauges. To compensate for the inertia force under the pulsatile flow, a 0.75-Hz low-pass filter was added to the electrical circuit. In the evaluation tests, numerical analysis and an actual measurement test using bovine blood were performed to evaluate the measurement performances. As a result, in the numerical analysis, the relationship between the differential pressure caused by centrifugal force and the flow rate was verified. In the actual measurement test, measurement error was less than ± 0.5 L/min, and the time delay was 0.12 s. We confirmed that the developed mass-flow meter was able to measure mass-flow rate continuously and noninvasively.

  2. Effects of the pulsatile flow settings on pulsatile waveforms and hemodynamic energy in a PediVAS centrifugal pump.

    PubMed

    Wang, Shigang; Rider, Alan R; Kunselman, Allen R; Richardson, J Scott; Dasse, Kurt A; Undar, Akif

    2009-01-01

    The objective of this study was to test different pulsatile flow settings of the PediVAS centrifugal pump to seek an optimum setting for pulsatile flow to achieve better pulsatile energy and minimal backflow. The PediVAS centrifugal pump and the conventional pediatric clinical circuit, including a pediatric membrane oxygenator, arterial filter, arterial cannula, and 1/4 in circuit tubing were used. The circuit was primed with 40% glycerin water mixture. Postcannula pressure was maintained at 40 mm Hg by a Hoffman clamp. The experiment was conducted at 800 ml/min of pump flow with a modified pulsatile flow setting at room temperature. Pump flow and pressure readings at preoxygenator and precannula sites were simultaneously recorded by a data acquisition system. The results showed that backflows appeared at flow rates of 200-800 ml/min (200 ml/min increments) with the default pulsatile flow setting and only at 200 ml/min with the modified pulsatile flow setting. With an increased rotational speed difference ratio and a decreased pulsatile width, the pulsatility increased in terms of surplus hemodynamic energy and total hemodynamic energy at preoxygenator and precannula sites. Backflows seemed at preoxygenator and precannula sites at a 70% of rotational speed difference ratio. The modified pulsatile flow setting was better than the default pulsatile flow setting in respect to pulsatile energy and backflow. The pulsatile width and the rotational speed difference ratio significantly affected pulsatility. The parameter of the rotational speed difference ratio can automatically increase pulsatility with increased rotational speeds. Further studies will be conducted to optimize the pulsatile flow setting of the centrifugal pump.

  3. Fluid dynamics aspects of miniaturized axial-flow blood pump.

    PubMed

    Kang, Can; Huang, Qifeng; Li, Yunxiao

    2014-01-01

    Rotary blood pump (RBP) is a kind of crucial ventricular assist device (VAD) and its advantages have been evidenced and acknowledged in recent years. Among the factors that influence the operation performance and the durability of various rotary blood pumps, medium property and the flow features in pump's flow passages are conceivably significant. The major concern in this paper is the fluid dynamics aspects of such a kind of miniaturized pump. More specifically, the structural features of axial-flow blood pump and corresponding flow features are analyzed in detail. The narrow flow passage between blade tips and pump casing and the rotor-stator interaction (RSI) zone may exert a negative effect on the shear stress distribution in the blood flow. Numerical techniques are briefly introduced in view of their contribution to facilitating the optimal design of blood pump and the visualization of shear stress distribution and multiphase flow analysis. Additionally, with the development of flow measurement techniques, the high-resolution, effective and non-intrusive flow measurement techniques catering to the measurement of the flows inside rotary blood pumps are highly anticipated.

  4. Platelet dysfunction in cardiopulmonary bypass: an experimental comparative study between a centrifugal and a new pulsatile pump.

    PubMed

    Herreros, J; Berjano, E J; Más, P; Padrós, C; Sales-Nebot, L; Vlaanderen, W; Díaz, P; Páramo, J A; Rábago, G; Mercé, S

    2003-12-01

    The aim of this investigation was to study the effect of a new pulsatile pump for extracorporeal circulation (ECC) on platelet count and platelet function with respect to a Biomedicus centrifugal pump. Thirteen pigs, 8 in the pulsatile group (PG) and 5 in the centrifugal group (CG), underwent a partial extracorporeal circulation lasting 3 h. The animals were sacrificed 3 h post-ECC. The platelet study was both quantitative (platelet count) and qualitative (platelet function analysis) by assessing the closure time (CT) with a PFA-100 system. The decrease in platelet number from basal to 3 h post ECC was only significant in CG (p = 0.009). The platelet function was impaired in both groups, but the value of CT with col/ADP increased significantly only in CG (p < 0.001). The increase of CT with col/EPI was greater in CG (p = 0.07) than in PG (p = 0.2). The results indicated that the new pulsatile pump preserves platelets quantitatively and qualitatively well compared to a Biomedicus pump.

  5. Noninvasive average flow estimation for an implantable rotary blood pump: a new algorithm incorporating the role of blood viscosity.

    PubMed

    Malagutti, Nicolò; Karantonis, Dean M; Cloherty, Shaun L; Ayre, Peter J; Mason, David G; Salamonsen, Robert F; Lovell, Nigel H

    2007-01-01

    The effect of blood hematocrit (HCT) on a noninvasive flow estimation algorithm was examined in a centrifugal implantable rotary blood pump (iRBP) used for ventricular assistance. An average flow estimator, based on three parameters, input electrical power, pump speed, and HCT, was developed. Data were collected in a mock loop under steady flow conditions for a variety of pump operating points and for various HCT levels. Analysis was performed using three-dimensional polynomial surfaces to fit the collected data for each different HCT level. The polynomial coefficients of the surfaces were then analyzed as a function of HCT. Linear correlations between estimated and measured pump flow over a flow range from 1.0 to 7.5 L/min resulted in a slope of 1.024 L/min (R2=0.9805). Early patient data tested against the estimator have shown promising consistency, suggesting that consideration of HCT can improve the accuracy of existing flow estimation algorithms.

  6. Noninvasive blood-flow meter using a curved cannula with zero compensation for an axial flow blood pump.

    PubMed

    Kosaka, Ryo; Fukuda, Kyohei; Nishida, Masahiro; Maruyama, Osamu; Yamane, Takashi

    2013-01-01

    In order to monitor the condition of a patient using a left ventricular assist system (LVAS), blood flow should be measured. However, the reliable determination of blood-flow rate has not been established. The purpose of the present study is to develop a noninvasive blood-flow meter using a curved cannula with zero compensation for an axial flow blood pump. The flow meter uses the centrifugal force generated by the flow rate in the curved cannula. Two strain gauges served as sensors. The first gauges were attached to the curved area to measure static pressure and centrifugal force, and the second gauges were attached to straight area to measure static pressure. The flow rate was determined by the differences in output from the two gauges. The zero compensation was constructed based on the consideration that the flow rate could be estimated during the initial driving condition and the ventricular suction condition without using the flow meter. A mock circulation loop was constructed in order to evaluate the measurement performance of the developed flow meter with zero compensation. As a result, the zero compensation worked effectively for the initial calibration and the zero-drift of the measured flow rate. We confirmed that the developed flow meter using a curved cannula with zero compensation was able to accurately measure the flow rate continuously and noninvasively.

  7. Design of an artificial left ventricular muscle: an innovative way to actuate blood pumps?

    PubMed

    Van Der Smissen, Benjamin; Claessens, Tom; Verdonck, Pascal; Van Ransbeeck, Peter; Segers, Patrick

    2009-06-01

    Blood pumps assist or take over the pump function of a failing heart. They are essentially activated by a pusher plate, a pneumatic compression of collapsible sacs, or they are driven by centrifugal pumps. Blood pumps relying upon one of these actuator mechanisms do not account for realistic wall deformation. In this study, we propose an innovative design of a blood pump actuator device which should be able to mimic fairly well global left ventricular (LV) wall deformation patterns in terms of circumferential and longitudinal contraction, as well as torsion. In order to reproduce these basic wall deformation patterns in our actuator device, we designed a novel kind of artificial LV "muscle" composed of multiple actively contracting cells. Its contraction is based on a mechanism by which pressurized air, inside such a cell, causes contraction in one direction and expansion perpendicular to this direction. The organization and geometry of the contractile cells within one artificial LV muscle, the applied pressure in the cells, and the governing LV loading conditions (preload and afterload) together determine the global deformation of the LV wall. Starting from a simple plastic bag, an experimental model based on the above mentioned principle was built and connected to a lumped hydraulic model of the vascular system (including compliance and resistance). The wall deformation pattern of this device was validated visually and its pump performance was studied in terms of LV volume and pressure and heart rate. Our experimental results revealed (i) a global LV motion resembling a real LV, and (ii) a close correlation between our model and a real LV in terms of end-systolic volume and pressure, end-diastolic volume and pressure, stroke volume, ejection fraction and pressure-volume relationship. Our proposed model appears promising and it can be considered as a step forward when compared to currently applied actuator mechanisms, as it will likely result in more physiological

  8. Influence of blade thickness on transient flow characteristics of centrifugal slurry pump with semi-open impeller

    NASA Astrophysics Data System (ADS)

    Tao, Yi; Yuan, Shouqi; Liu, Jianrui; Zhang, Fan; Tao, Jianping

    2016-10-01

    As the critical component, the impellers of the slurry pumps usually have blades of a large thickness. The increasing excretion coefficient of the blades affects the flow in the impeller resulting in a relatively higher hydraulic loss, which is rarely reported. In order to investigate the influence of blade thickness on the transient flow characteristics of a centrifugal slurry pump with a semi-open impeller, transient numerical simulations were carried out on six impellers, of which the meridional blade thickness from the leading edge to trailing edge varied from 5-10 mm, 5-15 mm, 5-20 mm, 10-10 mm, 10-15 mm, and 10-20 mm, respectively. Then, two of the six impellers, namely cases 4 and 6, were manufactured and experimentally tested for hydraulic performance to verify the simulation results. Results of these tests agreed reasonably well with those of the numerical simulation. The results demonstrate that when blade thickness increases, pressure fluctuations at the outlet of the impeller become severe. Moreover, the standard deviation of the relative velocity in the middle portion of the suction sides of the blades decreases and that at the outlet of the impeller increases. Thus, the amplitude of the impeller head pulsation for each case increases. Meanwhile, the distribution of the time-averaged relative flow angle becomes less uniform and decreases at the outlet of the impeller. Hence, as the impeller blade thickness increases, the pump head drops rapidly and the maximum efficiency point is offset to a lower flow rate condition. As the thickness of blade trailing edge increases by 10 mm, the head of the pump drops by approximately 5 m, which is approximately 10 % of the original pump head. Futhermore, it is for the first time that the time-averaged relative flow angle is being considered for the analysis of transient flow in centrifugal pump. The presented work could be a useful guideline in engineering practice when designing a centrifugal slurry pump with thick

  9. Coronary vascular resistance increases under full bypass support of centrifugal pumps--relation between myocardial perfusion and ventricular workload during pump support.

    PubMed

    Ando, Masahiko; Takewa, Yoshiaki; Nishimura, Takashi; Yamazaki, Kenji; Kyo, Shunei; Ono, Minoru; Tsukiya, Tomonori; Mizuno, Toshihide; Taenaka, Yoshiyuki; Tatsumi, Eisuke

    2012-01-01

    Coronary circulation is closely linked to myocardial oxygen consumption (MVO(2)), and previous reports have suggested decreased coronary flow (CoF) under left ventricular assist device support. Decreased CoF itself under support is not unfavorable because the native heart can be well unloaded and myocardial oxygen demand is also decreased. There should be an autoregulatory system that would maintain optimal CoF according to oxygen demand; however, the detailed mechanism is still unclear. The aim of the current study is to evaluate the effect of centrifugal pumps on CoF under varied bypass rates in relation to left ventricle workload. A centrifugal pump, EVAHEART (Sun Medical Technology Research Corporation, Nagano, Japan), was installed in an adult goat (n = 10, 61.3 ± 6.5 kg). We set up the following conditions, including Circuit-Clamp (i.e., no pump support), 50% bypass, and 100% bypass. In these settings, CoF, MVO(2), pressure-volume area (PVA), and coronary vascular resistance (CVR) were measured. In 100% bypass, CoF, MVO(2), and PVA were all decreased significantly from clamp. While in 50% bypass, CoF and MVO(2) decreased from clamp, but not PVA. There was a significant 40% increase in CVR in 100% bypass from clamp. This CVR increase in 100% bypass was possibly due to mechanical collapse of coronary vascular bed itself by pump support or increased vascular tone through autoregulatory system. In clinical settings, we should adjust optimal pump speed so as not to cause this vascular collapse. However, to clarify autoregulatory system of the coronary perfusion, further investigation is ongoing in ischemic and heart failure models.

  10. Measurements of gap pressure and wall shear stress of a blood pump model.

    PubMed

    Chua, L P; Akamatsu, T

    2000-04-01

    The centrifugal blood pump with a magnetically suspended impeller has shown its superiority as compared to other artificial hearts. However, there is still insufficient understanding of fluid mechanics related issues in the clearance gap. The design nature of the pump requires sufficient washout in the clearance between the impeller and stationary surfaces. As the gap is only 0.2 mm in width, it is very difficult to conduct measurements with present instrumentation. An enlarged model with 5:1 ratio of the pump has been designed and constructed according to specifications. Dimensionless gap pressure measurements of the model are very close to the prototype. The measurements of wall shear stress of the fluid flow in the clearance gap between the impeller face and inlet casing of a blood pump model were accomplished through hot-wire anemometry and rotating disk apparatus. Regions of relatively high and low shear stresses are identified. These correspond to spots where the likelihood of hemolysis and thrombus formation is high. With the use of dimensional analysis, it is found that the highest wall shear stress is equivalent to 146 Pa which is much lower than the threshold value of 400 Pa for hemolysis reported in the literature.

  11. A test program to measure fluid mechanical whirl-excitation forces in centrifugal pumps

    NASA Technical Reports Server (NTRS)

    Brennen, C. E.; Acosta, A. J.; Caughey, T. K.

    1980-01-01

    The details of a test program for the measurement of the unsteady forces on centrifugal impellers are discussed. Various hydrodynamic flows are identified as possible contributors to these destabilizing forces.

  12. Closed circuit cardiopulmonary bypass with centrifugal pump for open-heart surgery: new trial for air removal.

    PubMed

    Morita, M; Yozu, R; Matayoshi, T; Mitsumaru, A; Shin, H; Kawada, S

    2000-06-01

    The purpose of this study is to examine the efficiency of venous air removal with a new cardiopulmonary bypass (CPB) circuit design for conventional open-heart surgeries. A main concern with a closed circuit for open-heart surgeries is air entrainment into the venous line. A venous filter was placed proximal to the centrifugal pump. The circuit proximal to the centrifugal pump was divided into two lines; one line was attached to the venous reservoir outlet. By clamping the line to the reservoir, this circuit becomes closed. Negative pressure was applied to the purge line connected to the venous reservoir for venous air removal. Micro bubbles were measured at two locations, both distal to the venous and arterial filters. When the injection rate reached 100 ml/min, with the air-injection over 30 s, micro bubbles greater than 40 micro were observed at the outlet of venous filter. However, there was no micro bubble greater than 40 micro detected at the outlet of arterial filter. Although micro bubbles greater than 40 micro were not detected at the outlet of the arterial filter up to the injection rate of 300 ml/min, when the injection rate reached 400 ml/min, micro bubbles greater than 50 microm were detected distal to the arterial filter. From this examination, we determined that air entrained in the venous line up to approximately 300 ml/min is automatically removed by this method with the pressure-balanced condition. This pressure balance means that resistance of venous return, gravity siphon, negative pressure by centrifugal pump, and negative pressure applied to the air-purge line of the filter are balanced; that is, the venous return is sufficient, and the venous reservoir volume is kept stable. From this study we determined that this circuit design efficiently removes the entrained air in the venous line.

  13. Impact of the postpump resistance on pressure-flow waveform and hemodynamic energy level in a neonatal pulsatile centrifugal pump.

    PubMed

    Wang, Shigang; Haines, Nikkole; Richardson, J Scott; Dasse, Kurt A; Undar, Akif

    2009-01-01

    This study tested the impact of different postpump resistances on pulsatile pressure-flow waveforms and hemodynamic energy output in a mock extracorporeal system. The circuit was primed with a 40% glycerin-water mixture, and a PediVAS centrifugal pump was used. The pre- and postpump pressures and flow rates were monitored via a data acquisition system. The postpump resistance was adjusted using a Hoffman clamp at the outlet of the pump. Five different postpump resistances and rotational speeds were tested with nonpulsatile (NP: 5000 RPM) and pulsatile (P: 4000 RPM) modes. No backflow was found when using pulsatile flow. With isoresistance, increased arterial resistances decreased pump flow rates (NP: from 1,912 ml/min to 373 ml/min; P: from 1,485 ml/min to 288 ml/min), increased postpump pressures (NP: from 333 mm Hg to 402 mm Hg; P: from 223 mm Hg to 274 mm Hg), and increased hemodynamic energy output with pulsatile mode. Pump flow rate correlated linearly with rotational speed (RPMs) of the pump, whereas postpump pressures and hemodynamic energy outputs showed curvilinear relationships with RPMs. The maximal pump flow rate also increased from 618 ml/min to 4,293 ml/min with pulsatile mode and from 581 ml/min to 5,665 ml/min with nonpulsatile mode. Results showed that higher postpump resistance reduced the pump flow range, and increased postpump pressure and surplus hemodynamic energy output with pulsatile mode. Higher rotational speeds also generated higher pump flow rates, postpump pressures, and increased pulsatility.

  14. Experimental Fluid Mechanics of Pulsatile Artificial Blood Pumps

    NASA Astrophysics Data System (ADS)

    Deutsch, Steven; Tarbell, John M.; Manning, Keefe B.; Rosenberg, Gerson; Fontaine, Arnold A.

    2006-01-01

    The fluid mechanics of artificial blood pumps has been studied since the early 1970s in an attempt to understand and mitigate hemolysis and thrombus formation by the device. Pulsatile pumps are characterized by inlet jets that set up a rotational "washing" pattern during filling. Strong regurgitant jets through the closed artificial heart valves have Reynolds stresses on the order of 10,000 dynes/cm2 and are the most likely cause of red blood cell damage and platelet activation. Although the flow in the pump chamber appears benign, low wall shear stresses throughout the pump cycle can lead to thrombus formation at the wall of the smaller pumps (10 50 cc). The local fluid mechanics is critical. There is a need to rapidly measure or calculate the wall shear stress throughout the device so that the results may be easily incorporated into the design process.

  15. Servoregulation of centrifugal pumps. A new technical approach to improve patient safety during long-term extracorporeal life support.

    PubMed

    Müller, E; Münch, K

    1996-01-01

    The objective of this study was to evaluate the principle technical requirements to servoregulate a centrifugal pump (Bio-Pump) and to discuss the potential risks and benefits of the potential use of such a device during long-term extra-corporeal support in an experimental laboratory study. A pressure control module (PCM) for the Bio-Pump was developed and a pressure measurement chamber to indirectly measure pressure in the venous limb of an extracorporeal circuit was constructed. The performance of the PCM combined with the pressure measurement chamber was evaluated in an experimental test circuit by recording pressure changes after sudden clamping of the venous line with and without servoregulation. Without the PCM pressure dropped from baseline to approximately -200 mm Hg after clamping and remained at that level. With the PCM active the pump speed was automatically and immediately reduced and the preclamping pressure level (+/- 10 percent) was restored within 500 msec. In this laboratory setting the Bio-Pump could effectively and rapidly be servoregulated with a conventional controller and an indirect pressure monitoring system. A potential clinical use of this system could help to improve the safety without imposing additional risks such as air embolism or backflow.

  16. Experimental and Numerical Investigation of an Axial Rotary Blood Pump.

    PubMed

    Schüle, Chan Yong; Thamsen, Bente; Blümel, Bastian; Lommel, Michael; Karakaya, Tamer; Paschereit, Christian Oliver; Affeld, Klaus; Kertzscher, Ulrich

    2016-04-18

    Left ventricular assist devices (LVADs) have become a standard therapy for patients with severe heart failure. As low blood trauma in LVADs is important for a good clinical outcome, the assessment of the fluid loads inside the pump is critical. More specifically, the flow features on the surfaces where the interaction between blood and artificial material happens is of great importance. Therefore, experimental data for the near-wall flows in an axial rotary blood pump were collected and directly compared to computational fluid dynamic results. For this, the flow fields based on unsteady Reynolds-averaged Navier-Stokes simulations-computational fluid dynamics (URANS-CFD) of an axial rotary blood pump were calculated and compared with experimental flow data at one typical state of operation in an enlarged model of the pump. The focus was set on the assessment of wall shear stresses (WSS) at the housing wall and rotor gap region by means of the wall-particle image velocimetry technique, and the visualization of near-wall flow structures on the inner pump surfaces by a paint erosion method. Additionally, maximum WSS and tip leakage volume flows were measured for 13 different states of operation. Good agreement between CFD and experimental data was found, which includes the location, magnitude, and direction of the maximum and minimum WSS and the presence of recirculation zones on the pump stators. The maximum WSS increased linearly with pressure head. They occurred at the upstream third of the impeller blades and exceeded the critical values with respect to hemolysis. Regions of very high shear stresses and recirculation zones could be identified and were in good agreement with simulations. URANS-CFD, which is often used for pump performance and blood damage prediction, seems to be, therefore, a valid tool for the assessment of flow fields in axial rotary blood pumps. The magnitude of maximum WSS could be confirmed and were in the order of several hundred Pascal.

  17. 21 CFR 870.4370 - Roller-type cardiopulmonary bypass blood pump.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Roller-type cardiopulmonary bypass blood pump. 870... Roller-type cardiopulmonary bypass blood pump. (a) Identification. A roller-type cardiopulmonary bypass blood pump is a device that uses a revolving roller mechanism to pump the blood through...

  18. 21 CFR 870.4360 - Nonroller-type cardiopulmonary bypass blood pump.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Nonroller-type cardiopulmonary bypass blood pump... Nonroller-type cardiopulmonary bypass blood pump. (a) Identification. A nonroller-type cardiopulmonary bypass blood pump is a device that uses a method other than revolving rollers to pump the blood...

  19. 21 CFR 870.4360 - Nonroller-type cardiopulmonary bypass blood pump.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Nonroller-type cardiopulmonary bypass blood pump... Nonroller-type cardiopulmonary bypass blood pump. (a) Identification. A nonroller-type cardiopulmonary bypass blood pump is a device that uses a method other than revolving rollers to pump the blood...

  20. 21 CFR 870.4370 - Roller-type cardiopulmonary bypass blood pump.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Roller-type cardiopulmonary bypass blood pump. 870... Roller-type cardiopulmonary bypass blood pump. (a) Identification. A roller-type cardiopulmonary bypass blood pump is a device that uses a revolving roller mechanism to pump the blood through...

  1. 21 CFR 870.4370 - Roller-type cardiopulmonary bypass blood pump.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Roller-type cardiopulmonary bypass blood pump. 870... Roller-type cardiopulmonary bypass blood pump. (a) Identification. A roller-type cardiopulmonary bypass blood pump is a device that uses a revolving roller mechanism to pump the blood through...

  2. 21 CFR 870.4360 - Nonroller-type cardiopulmonary bypass blood pump.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Nonroller-type cardiopulmonary bypass blood pump... Nonroller-type cardiopulmonary bypass blood pump. (a) Identification. A nonroller-type cardiopulmonary bypass blood pump is a device that uses a method other than revolving rollers to pump the blood...

  3. 21 CFR 870.4370 - Roller-type cardiopulmonary bypass blood pump.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Roller-type cardiopulmonary bypass blood pump. 870... Roller-type cardiopulmonary bypass blood pump. (a) Identification. A roller-type cardiopulmonary bypass blood pump is a device that uses a revolving roller mechanism to pump the blood through...

  4. 21 CFR 870.4360 - Nonroller-type cardiopulmonary bypass blood pump.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Nonroller-type cardiopulmonary bypass blood pump... Nonroller-type cardiopulmonary bypass blood pump. (a) Identification. A nonroller-type cardiopulmonary bypass blood pump is a device that uses a method other than revolving rollers to pump the blood...

  5. 21 CFR 870.4360 - Nonroller-type cardiopulmonary bypass blood pump.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nonroller-type cardiopulmonary bypass blood pump... Nonroller-type cardiopulmonary bypass blood pump. (a) Identification. A nonroller-type cardiopulmonary bypass blood pump is a device that uses a method other than revolving rollers to pump the blood...

  6. 21 CFR 870.4370 - Roller-type cardiopulmonary bypass blood pump.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Roller-type cardiopulmonary bypass blood pump. 870... Roller-type cardiopulmonary bypass blood pump. (a) Identification. A roller-type cardiopulmonary bypass blood pump is a device that uses a revolving roller mechanism to pump the blood through...

  7. Centrifuge apparatus

    DOEpatents

    Sartory, Walter K.; Eveleigh, John W.

    1976-01-01

    A method and apparatus for operating a continuous flow blood separation centrifuge are provided. The hematocrit of the entrant whole blood is continuously maintained at an optimum constant value by the addition of plasma to the entrant blood. The hematocrit of the separated red cells is monitored to indicate the degree of separation taking place, thereby providing a basis for regulating the flow through the centrifuge.

  8. Centrifugal Pumps for Swimming Pools. National Sanitation Foundation Standard Number 17.

    ERIC Educational Resources Information Center

    National Sanitation Foundation, Ann Arbor, MI. Committee for Swimming Pool Equipment Standards.

    The pumps discussed herein are intended to be used for recirculating water in swimming pools, both public and private. Included are the basic components which may be a part of a pump such as the housing, strainer, impeller, valves, and such other parts as are attached or a part of the pump as supplied by the manufacturer. This standard is intended…

  9. Cultivation of shear stress sensitive and tolerant microalgal species in a tubular photobioreactor equipped with a centrifugal pump.

    PubMed

    Michels, Michiel H A; van der Goot, Atze Jan; Vermuë, Marian H; Wijffels, René H

    The tolerance to shear stress of Tetraselmis suecica, Isochrysis galbana, Skeletonema costatum, and Chaetoceros muelleri was determined in shear cylinders. The shear tolerance of the microalgae species strongly depends on the strain. I. galbana, S. costatum, and C. muelleri exposed to shear stress between 1.2 and 5.4 Pa resulted in severe cell damage. T. suecica is not sensitive to stresses up to 80 Pa. The possibility to grow these algae in a tubular photobioreactor (PBR) using a centrifugal pump for recirculation of the algae suspension was studied. The shear stresses imposed on the algae in the circulation tubes and at the pressure side of the pump were 0.57 and 1.82 Pa, respectively. The shear stress tolerant T. suecica was successfully cultivated in the PBR. Growth of I. galbana, S. costatum, and C. muelleri in the tubular PBR was not observed, not even at the lowest pumping speed. For the latter shear sensitive strains, the encountered shear stress levels were in the order of magnitude of the determined maximum shear tolerance of the algae. An equation was used to simulate the effect of possible damage of microalgae caused by passages through local high shear zones in centrifugal pumps on the total algae culture in the PBR. This simulation shows that a culture of shear stress sensitive species is bound to collapse after only limited number of passages, confirming the importance of considering shear stress as a process parameter in future design of closed PBRs for microalgal cultivation.

  10. Method and apparatus for automated processing and aliquoting of whole blood samples for analysis in a centrifugal fast analyzer

    DOEpatents

    Burtis, Carl A.; Johnson, Wayne F.; Walker, William A.

    1988-01-01

    A rotor and disc assembly for use in a centrifugal fast analyzer. The assembly is designed to process multiple samples of whole blood followed by aliquoting of the resultant serum into precisely measured samples for subsequent chemical analysis. The assembly requires minimal operator involvement with no mechanical pipetting. The system comprises (1) a whole blood sample disc, (2) a serum sample disc, (3) a sample preparation rotor, and (4) an analytical rotor. The blood sample disc and serum sample disc are designed with a plurality of precision bore capillary tubes arranged in a spoked array. Samples of blood are loaded into the blood sample disc in capillary tubes filled by capillary action and centrifugally discharged into cavities of the sample preparation rotor where separation of serum and solids is accomplished. The serum is loaded into the capillaries of the serum sample disc by capillary action and subsequently centrifugally expelled into cuvettes of the analytical rotor for analysis by conventional methods.

  11. Method and apparatus for automated processing and aliquoting of whole blood samples for analysis in a centrifugal fast analyzer

    DOEpatents

    Burtis, C.A.; Johnson, W.F.; Walker, W.A.

    1985-08-05

    A rotor and disc assembly for use in a centrifugal fast analyzer. The assembly is designed to process multiple samples of whole blood followed by aliquoting of the resultant serum into precisely measured samples for subsequent chemical analysis. The assembly requires minimal operator involvement with no mechanical pipetting. The system comprises: (1) a whole blood sample disc; (2) a serum sample disc; (3) a sample preparation rotor; and (4) an analytical rotor. The blood sample disc and serum sample disc are designed with a plurality of precision bore capillary tubes arranged in a spoked array. Samples of blood are loaded into the blood sample disc by capillary action and centrifugally discharged into cavities of the sample preparation rotor where separation of serum and solids is accomplished. The serum is loaded into the capillaries of the serum sample disc by capillary action and subsequently centrifugally expelled into cuvettes of the analyticaly rotor for conventional methods. 5 figs.

  12. Study on Internal Flow and External Performance of a Semi-open Impeller Centrifugal Pump with Different Tip Clearances

    NASA Astrophysics Data System (ADS)

    Jia, Xiao-Qi; Cui, Bao-Ling; Zhang, Yu-Liang; Zhu, Zu-Chao

    2015-04-01

    To study the influence of tip clearance on internal flow characteristics and external performance of a prototype centrifugal pump with a semi-open impeller, the unsteady numerical simulation and performance experiments are carried out in this paper. The evolution process of leakage vortex with time t, the flow characteristics and the magnitude of leakage rate in tip clearance are obtained in details. The results indicate that the H-Q curve hump of centrifugal pump shows a weakened trend with the increasing of tip clearance Δc. Meanwhile, the leakage rate ΔQ and the ratio of leakage rate to discharge flow rate (ψ) gradually increase. At the same tip clearance, the leakage rate ΔQ increases, while the ratio of leakage rate to discharge flow rate (ψ) decreases with the increasing of discharge flow rate Q. It is found that higher volumetric loss account for a higher percentage of the total loss at small flow rate condition. There easily exist strong leakage vortexes in the impeller inlet, impeller passage and impeller outlet. The pressure difference between suction side and pressure side makes the fluid pass through the tip clearance layer to form a lower pressure region and leakage vortex.

  13. Influence of Rotor-Stator Interaction on Flow Stability in Centrifugal Pump Based on Energy Gradient Method

    NASA Astrophysics Data System (ADS)

    Zheng, Lu-Lu; Dou, Hua-Shu; Jiang, Wei; Chen, Xiaoping; Zhu, Zuchao; Cui, Baoling

    2016-12-01

    Numerical simulation is performed for the three-dimensional turbulent flow field in a centrifugal pump by solving the Reynolds-averaged Navier-Stokes equations and the RNG k-epsilon turbulent model. The finite volume method and the SIMPLE algorithm are employed for the solution of the system. All the parameters in the centrifugal pump at different blade angular positions are obtained by simulation. The flow structure is analyzed and the distributions of the energy gradient function K are calculated at different blade angular positions based on the energy gradient method. According to the energy gradient method, the location which has larger value of K is easier to cause instability and to be of high turbulence intensity. The result shows that the flow instability is easier to be excited nearing the tongue where the value of K is large. The unstable flow area nearing the tongue is also in agreement with the zone where the velocity decreases rapidly. The sudden variation of velocity contributes to the large value of K. The research result also indicates that the tongue has large impact only on the impeller passages passing the tongue.

  14. Open-cycle centrifugal vapor-compression heat pump. Annual report, March 1983-February 1984

    SciTech Connect

    Iles, T.L.; Burgmeier, L.R.; Stanko, J.E.

    1984-04-01

    The objectives of this program are: (1) to develop an open-cycle high-lift centrifugal steam compressor system that can be efficiently retrofitted to existing multi-effect and high-temperature differential evaporators while maintaining the cost benefits of a single-stage centrifugal compressor and (2) to demonstrate the energy saving and cost benefits of driving the compressor with a natural-gas-fueled gas turbine engine. The turbine exhaust will be used for final drying of the product that was evaporated. This report describes the design and fabrication of the system and the test activities through February 1984.

  15. Open-cycle centrifugal vapor-compression heat pump. Annual report, March 1984-February 1985

    SciTech Connect

    Iles, T.L.; Burgmeier, L.R.; Liu, A.Y.

    1985-04-01

    The objectives of the program are to (1) develop an open-cycle high-lift centrifugal steam compressor system that can be efficiently retrofitted to existing multi-effect and high-temperature differential evaporators while maintaining the cost benefits of a single-stage centrifugal compressor and (2) demonstrate the energy saving and cost benefits of driving the compressor with a natural-gas-fueled gas turbine engine. The turbine exhaust will be used for final drying of the product that was evaporated. This report describes the design and fabrication of the system and the test activities through February 1985.

  16. Open-cycle centrifugal vapor-compression heat pump. Final report, January 1986-May 1987

    SciTech Connect

    Burgmeier, L.R.; Horner, J.E.

    1987-11-30

    The objectives of the program were (1) to develop an open-cycle, high-lift, centrifugal steam-compressor system that can be efficiently retrofitted to existing multi-effect and high-temperature differential evaporators while maintaining the cost benefits of a single-stage centrifugal compressor, and (2) to demonstrate the energy saving and cost benefits of driving the compressor with a natural-gas-fueled gas-turbine engine. The turbine exhaust was to be used for final drying of the product that was evaporated. The report describes the installation of the system and the test activities through May 1987.

  17. Tip clearance effects on loads and performances of semi-open impeller centrifugal pumps at different specific speeds

    NASA Astrophysics Data System (ADS)

    Boitel, G.; Fedala, D.; Myon, N.

    2016-11-01

    Relevant industrial standards or customer's specifications could strictly forbid any device adjusting the axial rotor/stator position, so that tip clearance between semi-open impeller and casing might become a result of the pump machining tolerances and assembling process, leading to big tip clearance variations compared to its nominal value. Consequently, large disparities of global performances (head, power, efficiency) and axial loads are observed with high risk of both specifications noncompliance and bearing damages. This work aims at quantifying these variations by taking into account tip clearance value and pump specific speed. Computational Fluid Dynamics is used to investigate this phenomenon by means of steady simulations led on a semi-open centrifugal pump numerical model including secondary flows, based on a k-omega SST turbulence model. Four different specific speed pump sizes are simulated (from 8 to 50, SI units), with three tip clearances for each size on a wide flow range (from 40% to 120% of the best efficiency point). The numerical results clearly show that head, power and efficiency increase as the tip clearance decreases for the whole flow range. This effect is more significant when the specific speed is low. Meanwhile, the resulting axial thrust on the impeller is very sensitive to the tip clearance and can even lead to direction inversion.

  18. An ultradurable and compact rotary blood pump with a magnetically suspended impeller in the radial direction.

    PubMed

    Masuzawa, T; Kita, T; Okada, Y

    2001-05-01

    A magnetically suspended centrifugal blood pump has been developed with a self-bearing motor for long-term ventricular assist systems. The rotor of the self-bearing motor is not only actively suspended in the radial direction, but also is rotated by an electromagnetic field. The pump has a long lifetime because there are no mechanical parts such as seals and motor bearings. An outer rotor mechanism was adopted for the self-bearing motor. The stator was constructed in the central space of the motor. The rotor shaped thin ring was set at the circumferential space of the stator. Six vanes were extended from the upper surface of the rotor toward the center of the pump to construct an open-type impeller. The outer diameter and the height of the impeller are 63 mm and 34 mm, respectively. The magnetic bearing method and the servomotor mechanism were adopted to levitate and rotate the rotor. Radial movements of the rotor and rotation are controlled actively by using electromagnets in the stator. Axial movement and tilt of the rotor are restricted by passive stability to simplify the control. The radial gap between the rotor and the stator is 1 mm. A closed-loop circuit filled with water was used to examine basic performance of the pump. Maximum flow rate and pressure head were 8 L/min and 200 mm Hg, respectively. Maximum amplitude of radial displacement of the impeller was 0.15 mm. The impeller could be suspended completely without touching the casing wall during the entire pumping process. Power consumption of the pump was only 9.5 W to produce a flow rate of 5 L/min against a pressure head of 100 mm Hg. We conclude that the pump has sufficient performance for the implantable ventricular assist system.

  19. Classification of Implantable Rotary Blood Pump States With Class Noise.

    PubMed

    Ooi, Hui-Lee; Seera, Manjeevan; Ng, Siew-Cheok; Lim, Chee Peng; Loo, Chu Kiong; Lovell, Nigel H; Redmond, Stephen J; Lim, Einly

    2016-05-01

    A medical case study related to implantable rotary blood pumps is examined. Five classifiers and two ensemble classifiers are applied to process the signals collected from the pumps for the identification of the aortic valve nonopening pump state. In addition to the noise-free datasets, up to 40% class noise has been added to the signals to evaluate the classification performance when mislabeling is present in the classifier training set. In order to ensure a reliable diagnostic model for the identification of the pump states, classifications performed with and without class noise are evaluated. The multilayer perceptron emerged as the best performing classifier for pump state detection due to its high accuracy as well as robustness against class noise.

  20. Development of a mercury electromagnetic centrifugal pump for the SNAP-8 refractory boiler development program

    NASA Technical Reports Server (NTRS)

    Fuller, R. A.; Schnacke, A. W.

    1974-01-01

    An electromagnetic pump, in which pressure is developed in mercury because of the interaction of the magnetic field and current which flows as a result of the voltage induced in the mercury contained in the pump duct, was developed for the SNAP-8 refractory boiler test facility. Pump performance results are presented for ten duct configurations and two stator sizes. These test results were used to design and fabricate a pump which met the SNAP-8 criteria of 530 psi developed pressure at 12,500 lb/hr. The pump operated continuously for over 13,000 hours without failure or performance degradation. Included in this report are descriptions of the experimental equipment, measurement techniques, all experimental data, and an analysis of the electrical losses in the pump.

  1. Preliminary validation of a new magnetic wireless blood pump.

    PubMed

    Kim, Sung Hoon; Ishiyama, Kazushi; Hashi, Shuichiro; Shiraishi, Yasuyuki; Hayatsu, Yukihiro; Akiyama, Masatoshi; Saiki, Yoshikatsu; Yambe, Tomoyuki

    2013-10-01

    In general, a blood pump must be small, have a simple configuration, and have sufficient hydrodynamic performance. Herein, we introduce new mechanisms for a wireless blood pump that is small and simple and provides wireless and battery-free operation. To achieve wireless and battery-free operation, we implement magnetic torque and force control methods that use two external drivers: an external coil and a permanent magnet with a DC-motor, respectively. Power harvesting can be used to drive an electronic circuit for wireless monitoring (the observation of the pump conditions and temperature) without the use of an internal battery. The power harvesting will be used as a power source to drive other electronic devices, such as various biosensors with their driving circuits. To have both a compact size and sufficient pumping capability, the fully magnetic impeller has five stages and each stage includes four backward-curved blades. The pump has total and inner volumes of 20 and 9.8 cc, respectively, and weighs 52 g. The pump produces a flow rate of approximately 8 L/min at 80 mm Hg and the power generator produces 0.3 W of electrical power at 120 Ω. The pump also produces a minimum flow rate of 1.5 L/min and a pressure of 30 mm Hg for circulation at a maximum distance of 7.5 cm.

  2. 85,000-GPM, single-stage, single-suction LMFBR intermediate centrifugal pump

    SciTech Connect

    Fair, C.E.; Cook, M.E. Huber, K.A.; Rohde, R.

    1983-01-01

    The mechanical and hydraulic design features of the 85,000-gpm, single-stage, single-suction pump test article, which is designed to circulate liquid-sodium coolant in the intermediate heat-transport system of a Large-Scale Liquid Metal Fast Breeder Reactor (LS-LMFBR), are described. The design and analytical considerations used to satisfy the pump performance and operability requirements are presented. The validation of pump hydraulic performance using a hydraulic scale-model pump is discussed, as is the featute test for the mechanical-shaft seal system.

  3. Classification of physiologically significant pumping states in an implantable rotary blood pump: patient trial results.

    PubMed

    Karantonis, Dean M; Mason, David G; Salamonsen, Robert F; Ayre, Peter J; Cloherty, Shaun L; Lovell, Nigel H

    2007-01-01

    An integral component in the development of a control strategy for implantable rotary blood pumps is the task of reliably detecting the occurrence of left ventricular collapse due to overpumping of the native heart. Using the noninvasive pump feedback signal of impeller speed, an approach to distinguish between overpumping (or ventricular collapse) and the normal pumping state has been developed. Noninvasive pump signals from 10 human pump recipients were collected, and the pumping state was categorized as either normal or suction, based on expert opinion aided by transesophageal echocardiographic images. A number of indices derived from the pump speed waveform were incorporated into a classification and regression tree model, which acted as the pumping state classifier. When validating the model on 12,990 segments of unseen data, this methodology yielded a peak sensitivity/specificity for detecting suction of 99.11%/98.76%. After performing a 10-fold cross-validation on all of the available data, a minimum estimated error of 0.53% was achieved. The results presented suggest that techniques for pumping state detection, previously investigated in preliminary in vivo studies, are applicable and sufficient for use in the clinical environment.

  4. A ferrofluidic seal specially designed for rotary blood pumps.

    PubMed

    Mitamura, Y; Fujiyoshi, M; Yoshida, T; Yozu, R; Okamoto, E; Tanaka, T; Kawada, S

    1996-06-01

    One of the key technologies required for rotary blood pumps is sealing of the motor shaft. A ferrofluidic seal was developed for an axial flow pump. The seal body was composed of a plastic magnet and two pole pieces. This seal was formed by injecting ferrofluid into the gap between the pole pieces and the motor shaft. To contain the ferrofluid in the seal and to minimize the possibility of ferrofluid making contact with blood, a shield with a small cavity was provided on the pole piece. Sealing pressure of the seal was measured. The sealing pressure was maintained at more than 23.3 kPa (175 mm Hg) for a motor speed up to 11,000 rpm. The specially designed ferrofluidic seal for sealing out liquids is useful for axial flow blood pumps.

  5. Application of a magnetic fluid seal to rotary blood pumps.

    PubMed

    Mitamura, Y; Arioka, S; Sakota, D; Sekine, K; Azegami, M

    2008-05-21

    A magnetic fluid seal enables mechanical contact-free rotation of a shaft without frictional heat and material wear and hence has excellent durability. However, the durability of a magnetic fluid seal decreases in liquid. The life of a seal applied to a rotary blood pump is not known. We have developed a magnetic fluid seal that has a shield mechanism minimizing the influence of the rotary pump on the magnetic fluid. The developed magnetic fluid seal worked for over 286 days in a continuous flow condition, for 24 days (on-going) in a pulsatile flow condition and for 24 h (electively terminated) in blood flow. The magnetic fluid seal is promising as a shaft seal for rotary blood pumps.

  6. Parameter estimation and actuator characteristics of hybrid magnetic bearings for axial flow blood pump applications.

    PubMed

    Lim, Tau Meng; Cheng, Shanbao; Chua, Leok Poh

    2009-07-01

    Axial flow blood pumps are generally smaller as compared to centrifugal pumps. This is very beneficial because they can provide better anatomical fit in the chest cavity, as well as lower the risk of infection. This article discusses the design, levitated responses, and parameter estimation of the dynamic characteristics of a compact hybrid magnetic bearing (HMB) system for axial flow blood pump applications. The rotor/impeller of the pump is driven by a three-phase permanent magnet brushless and sensorless motor. It is levitated by two HMBs at both ends in five degree of freedom with proportional-integral-derivative controllers, among which four radial directions are actively controlled and one axial direction is passively controlled. The frequency domain parameter estimation technique with statistical analysis is adopted to validate the stiffness and damping coefficients of the HMB system. A specially designed test rig facilitated the estimation of the bearing's coefficients in air-in both the radial and axial directions. Experimental estimation showed that the dynamic characteristics of the HMB system are dominated by the frequency-dependent stiffness coefficients. By injecting a multifrequency excitation force signal onto the rotor through the HMBs, it is noticed in the experimental results the maximum displacement linear operating range is 20% of the static eccentricity with respect to the rotor and stator gap clearance. The actuator gain was also successfully calibrated and may potentially extend the parameter estimation technique developed in the study of identification and monitoring of the pump's dynamic properties under normal operating conditions with fluid.

  7. Designing and modeling a centrifugal microfluidic device to separate target blood cells

    NASA Astrophysics Data System (ADS)

    Shamloo, Amir; Selahi, AmirAli; Madadelahi, Masoud

    2016-03-01

    The objective of this study is to design a novel and efficient portable lab-on-a-CD (LOCD) microfluidic device for separation of specific cells (target cells) using magnetic beads. In this study the results are shown for neutrophils as target cells. However, other kinds of target cells can be separated in a similar approach. The designed microfluidics can be utilized as a point of care system for neutrophil detection. This microfluidic system employs centrifugal and magnetic forces for separation. After model validation by the experimental data in the literature (that may be used as a design tool for developing centrifugo-magnetophoretic devices), two models are presented for separation of target cells using magnetic beads. The first model consists of one container in the inlet section and two containers in the outlets. Initially, the inlet container is filled with diluted blood sample which is a mixture of red blood cells (RBCs) plus neutrophils which are attached to Magnetic beads. It is shown that by using centrifugal and magnetic forces, this model can separate all neutrophils with recovery factor of ~100%. In the second model, due to excess of magnetic beads in usual experimental analysis (to ensure that all target cells are attached to them) the geometry is improved by adding a third outlet for these free magnetic beads. It is shown that at angular velocity of 45 rad s-1, recovery factor of 100% is achievable for RBCs, free magnetic beads and neutrophils as target cells.

  8. Condition monitoring of rotary blood pumps.

    PubMed

    Jammu, V B; Malanoski, S; Walter, T; Smith, W

    1997-01-01

    Long-term, trouble-free operation of ventricular assist devices (VADs) is critical to the patient. A catastrophic failure of the VAD could cost the patient's life, thus defeating the purpose of the device. The targeted 90% 5 year reliability also implies that the average device life would exceed the 5 year limit. Time based explantation of the device after the fifth year will replace many devices with significant additional life, subject the patient to unnecessary surgical risk, and increase costs. To preclude the need for time based replacements and prevent catastrophic failures, a condition monitor is proposed in this article for early detection of faults in VADs. To develop this monitor, the effectiveness of various sensing and monitoring methods for determining the VAD condition is investigated. A Hemadyne pump was instrumented with a set of eight sensors, and a series of experiments were performed to record and analyze signals from the normal and abnormal pumps with five different faults. Statistical, spectral, envelope, and ensemble averaging analyses were performed to characterize changes in sensor signals due to faults. Experimental results indicate that statistical and frequency information from the acceleration and dynamic pressure signals can clearly detect and identify various VAD faults.

  9. Quantitative approach to control spinning stability of the impeller in the pivot bearing-supported centrifugal pump.

    PubMed

    Takami, Y; Makinouchi, K; Otsuka, G; Nosé, Y

    1997-12-01

    The Gyro C1E3 pump has been developed as a completely sealless centrifugal pump driven by a magnetic coupling system for long-term usage. The Gyro C1E3 pump is a pivot bearing-supported pump in which the impeller is supported with the top and bottom pivot bearings. In the Gyro C1E3 pump, the impeller spinning is affected by the force balance between the floating force (Ff[N]) of the hydrodynamic effect and the magnetic thrust force (Tf[N]). The authors quantitatively investigated the floating force of the impeller in vitro to determine the magnetic coupling distance (MCD[mm]) that would result in stable impeller spinning. In vitro tests were performed using a loop filled with 37% glycerin solution to obtain the relationship between the MCD and floating speed (Rf, rotational speed when the impeller starts floating [rpm]) and the relationship between the MCD and Tf. From the obtained relationships, we calculated Ff and determined the relationship between the Ff and the rotational speed (R). Furthermore, we determined the relationship between d (minimum required MCD [mm]) and R from the results of determining the relationship of the MCD and Tf and of the Ff and R. The following relationships were obtained: Rf = 6.24 x 10(4) x MCD-1.35; Tf = 5.27 x 10(3) x MCD-2.29; Ff = 4.71 x 10(-6) x RPM1.69; and d = 9.02 x RPM-0.85 where RPM is the rotational speed. It was demonstrated that the floating force of the impeller is a function only of the rotational speed in the pivot bearing-supported Gyro C1E3 pump. The floating force is estimated to be 10 N to 40 N at rotational speeds of 1,500 rpm to 3,000 rpm at which the Gyro pump may be used in most clinical situations. It would be possible to control the impeller position of the Gyro pump automatically at the stable spinning condition by controlling the adequate magnetic coupling distance based upon its relationship with the rotational speed which was obtained in this study.

  10. Design and construction of a mechatronic robot with five degrees of freedom that locates internal porosity in centrifugal pumps

    NASA Astrophysics Data System (ADS)

    Bautista-Elivar, N.; Uribe-Fernández, U.; Ruiz-Conteras, F.; Santillan-Gutierrez, D.; Sánchez-Hernández, C.; Robledo-Sánchez, C.

    2009-09-01

    In this paper is presented construction and implementation of a mechatronic robot to obtain porosity in parts mechanics of centrifugal pumps using ultrasonic wave. Considerations about the methods applied and their use in the field of metrology for the metal mechanic industry are taken into consideration. This project is inserted in ITT Goulds Pumps industries, with a headquarter in Tizayuca Hidalgo State, Mexico. A mechatronic robot with 5 free grades (XYZUV) of 170 X 104 X 120 cm controlled by a PC is built. The robot let us scan metal mechanic pieces of 120 X 90 X 170 cm. It is incorporated a sensor ultrasonic in miniature in the Z axis. Such arrangement allows applying the techniques of ultrasonic wave to obtain maps of porosity in parts mechanics in manufacturing pumps to test mechanic deformation. The scan is done by the Z axis when traveling around the piece under test with the objective of finding fragility zones when applying cutting efforts to the pieces.

  11. New investigations of a pulsatile impeller blood pump.

    PubMed

    Qian, K X

    1990-01-01

    For circulatory assist devices and total artificial heart systems, impeller blood pumps with small total volumes would be fully implantable. One of the main obstacles, however, is generation of a pulsatile flow. The simplest way to overcome this problem is by changing the pump's revolutions per minute (rpm) periodically, but this often results in severe hemolysis. After theoretic analysis, two in vitro models of impeller blood pumps have been devised, producing pulsatile flow with constant rpm. In the first model, the impeller oscillates in an axial direction during constant rotation. The pump is driven by a DC motor (rotating) and a pneumatic device (oscillating). The form of the pulsatile pressure wave depends upon duration and amplitude of the oscillation. With 40% systolic duration and a 50 mm axial amplitude, a 70 mmHg pressure amplitude (170/100) is achieved with a semiphysiologic shape at a flow of 12 L/min. The second model produces a pulsatile flow by differing the gaps between impeller and cap on the inlet pipe. Both the cap and impeller have cone-shaped heads, and impeller oscillations of 1.5-2 mm, for example, results in a pressure pulse of 40 mmHg (150-110) at 7 L/min flow. Results of theoretic analyses have shown that both models create less turbulence in the impeller, with a consequent reduction in blood cell damage as compared to pumps with changing rpms.

  12. An electromagnetic pneumatic blood pump driver.

    PubMed

    Whalen, R L; Briskman, R N

    1988-01-01

    An electromagnetic pneumatic pump driver has been developed with the goals of enhanced mechanical reliability and simplicity of operation. The new driver eliminates failure prone components such as solenoid valves or pressure regulators common to conventional pneumatic drive systems, has only a single moving part, and provides for closed-loop operation in which stroke volume and dP/dT are controlled on each beat in real time. Power is provided by a high force (178 N) electromagnetic linear actuator. This assembly uses a high energy density neodymium-iron-boron permanent magnet, low loss vanadium alloy pole pieces, and an energized moving coil. The nominal stroke length of the actuator is 1.7 cm. During operation, the moving coil always remains within a fixed annular air gap, resulting in a measured force output versus applied power linearity of better than 92% over its stroke range. The coil is directly attached to the free end of a 10 cm diameter, 21 convolution, welded titanium metal bellows that forms the gas containing element of the system. The comparatively low pressure gradients across the bellows in this application result in a predicted life for the bellows in excess of 10(9) cycles. Bellows position and internal pressure are monitored continuously to control the pneumatic output. The linear actuator total excursion and velocity are adjusted on each beat using a closed-loop servo system. This results in a pump driver with no operator required adjustment of drive pressure. Instead, there are user selected settings of stroke volume, operating mode, and fill sensitivity.(ABSTRACT TRUNCATED AT 250 WORDS)

  13. A travelling wave dielectrophoretic pump for blood delivery.

    PubMed

    Lei, U; Huang, C W; Chen, James; Yang, C Y; Lo, Y J; Wo, Andrew; Chen, C F; Fung, T W

    2009-05-21

    The travelling wave dielectrophoretic pump studied here is essentially a rectangular straight micro-channel with an electrode array on part of its wall, and operated under an ac voltage with phase shift at neighbouring electrodes. The travelling wave dielectrophoretic force drives the cells, which drag the plasma, and after some sophisticated interaction between conventional dielectrophoresis, travelling wave dielectrophoresis and fluid mechanics, the whole blood is delivered. The pump was fabricated using MEMS techniques and studied in details for different parameters. It is found that the pumping velocity is maximized at an intermediate frequency around 20-30 MHz (varies with phase shift), and at an intermediate channel height at about 40 microm. The quasi-static average cell velocity can reach 15 microm s(-1) for a pump with 1 mm length and 16 electrodes (total array length 465 microm) operated at 5 V and 20 MHz with 90 degrees phase shift.

  14. Directly observed reversible shape changes and hemoglobin stratification during centrifugation of human and Amphiuma red blood cells.

    PubMed

    Hoffman, Joseph F; Inoué, Shinya

    2006-02-21

    This paper describes changes that occur in human and Amphiuma red blood cells observed during centrifugation with a special microscope. Dilute suspensions of cells were layered, in a centrifuge chamber, above an osmotically matched dense solution, containing Nycodenz, Ficoll, or Percoll (Pharmacia) that formed a density gradient that allowed the cells to slowly settle to an equilibrium position. Biconcave human red blood cells moved downward at low forces with minimum wobble. The cells oriented vertically when the force field was increased and Hb sedimented as the lower part of each cell became bulged and assumed a "bag-like" shape. The upper centripetal portion of the cell became thinner and remained biconcave. These changes occurred rapidly and were completely reversible upon lowering the centrifugal force. Bag-shaped cells, upon touching red cells in rouleau, immediately reverted to biconcave disks as they flipped onto a stack. Amphiuma red cells displayed a different type of reversible stratification and deformation at high force fields. Here the cells became stretched, with the nucleus now moving centrifugally, the Hb moving centripetally, and the bottom of the cells becoming thinner and clear. Nevertheless, the distribution of the marginal bands at the cells' rim was unchanged. We conclude that centrifugation, per se, while changing a red cell's shape and the distribution of its intracellular constituents, does so in a completely reversible manner. Centrifugation of red cells harboring altered or missing structural elements could provide information on shape determinants that are still unexplained.

  15. Designing a combined casting mold for manufacture of a gasoline centrifugal pump body using CAD/CAM-systems

    NASA Astrophysics Data System (ADS)

    Galin, N. E.; Ogol, I. I.; Chervach, Yu B.; Dammer, V. Kh; Ru, Jia Hong

    2017-02-01

    The present paper examines designing of a combined casting mold for manufacture of a gasoline centrifugal pump body. The paper offers technological solutions for obtaining high quality castings at the testing stage of the finished mold. The paper is intended for practical use and prepared by order of JSC ‘Tomsk Electrical Engineering Plant’ using software and equipment of the department ‘Technologies of Computer-Aided Machinery Manufacturing’ of the Tomsk Polytechnic University (TPU) under the economic contract within state import substitution program. In preparing the paper, CAD/CAM-systems KOMPAS-3D and PowerMILL were used. In 2015, the designed casting mold was introduced into the production process at JSC ‘Tomsk Electrical Engineering Plant’.

  16. Blood Pump Development Using Rocket Engine Flow Simulation Technology

    NASA Technical Reports Server (NTRS)

    Kwak, Dochan; Kiris, Cetin

    2001-01-01

    This paper reports the progress made towards developing complete blood flow simulation capability in humans, especially in the presence of artificial devices such as valves and ventricular assist devices. Devices modeling poses unique challenges different from computing the blood flow in natural hearts and arteries. There are many elements needed to quantify the flow in these devices such as flow solvers, geometry modeling including flexible walls, moving boundary procedures and physiological characterization of blood. As a first step, computational technology developed for aerospace applications was extended to the analysis and development of a ventricular assist device (VAD), i.e., a blood pump. The blood flow in a VAD is practically incompressible and Newtonian, and thus an incompressible Navier-Stokes solution procedure can be applied. A primitive variable formulation is used in conjunction with the overset grid approach to handle complex moving geometry. The primary purpose of developing the incompressible flow analysis capability was to quantify the flow in advanced turbopump for space propulsion system. The same procedure has been extended to the development of NASA-DeBakey VAD that is based on an axial blood pump. Due to massive computing requirements, high-end computing is necessary for simulating three-dimensional flow in these pumps. Computational, experimental, and clinical results are presented.

  17. Dynamic characteristics and mechatronics model for maglev blood pump

    NASA Astrophysics Data System (ADS)

    Sun, Kun; Chen, Chen

    2017-01-01

    Magnetic bearing system(MBs) has been developed in the new-generation blood pump due to its low power consumption, low blood trauma and high durability. However, MBs for a blood pump were almost influenced by a series of factors such as hemodynamics, rotation speeds and actuator response in working fluids, compared with those applied in other industrial fields. In this study, the dynamic characteristics of MBs in fluid environments, including the influence of the pumping fluid and rotation of the impeller on the radial dynamic model were investigated by measuring the frequency response to sinusoidal excitation upon coils, and the response of radial displacement during a raise in the speed. The excitation tests were conducted under conditions in which the blood pump was levitated in air and water and with or without rotation. The experimental and simulated results indicate that rotations of the impeller affected the characteristics of MBs in water apparently, and the vibration in water was decreased, compared with that in air due to the hydraulic force. During the start-up and rotation, the actuator failed to operate fully and timely, and the voltage supplied can be chosen under the consideration of the rotor displacement and consumption.

  18. Internal hydraulic analysis of impeller rounding in centrifugal pumps as turbines

    SciTech Connect

    Singh, Punit; Nestmann, Franz

    2011-01-15

    The use of pumps as turbines in different applications has been gaining importance in the recent years, but the subject of hydraulic optimization still remains an open research problem. One of these optimization techniques that include rounding of the sharp edges at the impeller periphery (or turbine inlet) has shown tendencies of performance enhancement. In order to understand the effect of this hydraulic optimization, the paper introduces an analytical model in the pump as turbine control volume and brings out the functionalities of the internal variables classified under control variables consisting of the system loss coefficient and exit relative flow direction and under dependent variables consisting of net tangential flow velocity, net head and efficiency. The paper studies the effects of impeller rounding on a combination of radial flow and mixed flow pumps as turbines using experimental data. The impeller rounding is seen to have positive impact on the overall efficiency in different operating regions with an improvement in the range of 1-3%. The behaviour of the two control variables have been elaborately studied in which it is found that the system loss coefficient has reduced drastically due to rounding effects, while the extent of changes to the exit relative flow direction seems to be limited in comparison. The reasons for changes to these control variables have been physically interpreted and attributed to the behaviour of the wake zone at the turbine inlet and circulation within the impeller control volume. The larger picture of impeller rounding has been discussed in comparison with performance prediction models in pumps as turbines. The possible limitations of the analytical model as well as the test setup are also presented. The paper concludes that the impeller rounding technique is very important for performance optimization and recommends its application on all pump as turbine projects. It also recommends the standardization of the rounding

  19. Effects of intra-aortic balloon pump versus centrifugal pump on myocardial energetics and systemic circulation in a porcine model of rapidly worsening acute heart failure.

    PubMed

    Ntalianis, Argyrios S; Drakos, Stavros G; Charitos, Christos; Dolou, Paraskevi; Pierrakos, Charalampos N; Terrovitis, John V; Papaioannou, Theodoros; Charitos, Efstratios; Nanas, John N

    2008-01-01

    The present experimental study compared the effectiveness of counterpulsation provided by the intra-aortic balloon pump (IABP) versus that of a nonpulsatile, radial-flow centrifugal pump (CFP) in rapidly worsening acute heart failure (HF). Eighteen pigs were included in the study. After the induction of acute moderate HF, circulatory support was randomly provided with either the IABP or CFP. No significant change in cardiac output (CO) and mean aortic pressure (MAP) was observed with either pump. The IABP caused a significantly greater decrease than the CFP in 1) double product (13.138 +/- 2.476 mm Hg/min vs. 14.217 +/- 2.673 mm Hg/min, p = 0.023), 2) left ventricular systolic pressure (LVSP, 100 +/- 8 mm Hg vs. 106 +/- 10 mm Hg, p = 0.046), and 3) end-diastolic aortic pressure (EDAP, 70 +/- 6 mm Hg vs. 86 +/- 6 mm Hg, p = 0.000). The effects of both pumps on total tension time index and LAD flow were similar. After the induction of severe HF, the IABP had its main effects on afterload and decreased LVSP from 88 +/- 6 mm Hg to 78 +/- 9 mm Hg, (p = 0.008), and EDAP from 57 +/- 9 mm Hg to 49 +/- 14 mm Hg, (p = 0.044), whereas the CFP exerted its effects mainly on preload, lowering LV end-diastolic pressure from 19 +/- 5 mm Hg to 11 +/- 4 mm Hg, (p = 0.002). CO and MAP were similarly increased by both assist systems. The IABP (by lowering afterload) and CFP (by lowering preload) both offered significant mechanical support in acute HF. However, afterload reduction offered principally by the IABP seems preferable for the recovery of the acutely failing heart.

  20. Impact of hyperthermal rotary blood pump surfaces on blood clotting behavior: an approach.

    PubMed

    Hamilton, Kathrin F; Schlanstein, Peter C; Mager, Ilona; Schmitz-Rode, Thomas; Steinseifer, Ulrich

    2009-09-01

    The influence of heat dissipating systems, such as rotary blood pumps, was investigated. Titanium cylinders as rotary blood pump housing dummies were immersed in porcine blood and constantly tempered at specific temperatures (37-60 degrees C) over a defined period of time. The porcine blood was anticoagulated either by low heparin dosage or citrate. At frequent intervals, samples were taken for blood analysis and the determination of the plasmatic coagulation cascade. Blood parameters do not alter at surface temperatures below 50 degrees C. Hyperthermia-induced hemolysis could be confirmed. The plasmatic coagulation cascade is terminated at surface temperatures exceeding 55 degrees C. The adhesion of blood constituents on surfaces is temperature and time dependent, and structural changes of adhesions and blood itself were detected.

  1. Noninvasive activity-based control of an implantable rotary blood pump: comparative software simulation study.

    PubMed

    Karantonis, Dean M; Lim, Einly; Mason, David G; Salamonsen, Robert F; Ayre, Peter J; Lovell, Nigel H

    2010-02-01

    A control algorithm for an implantable centrifugal rotary blood pump (RBP) based on a noninvasive indicator of the implant recipient's activity level has been proposed and evaluated in a software simulation environment. An activity level index (ALI)-derived from a noninvasive estimate of heart rate and the output of a triaxial accelerometer-forms the noninvasive indicator of metabolic energy expenditure. Pump speed is then varied linearly according to the ALI within a defined range. This ALI-based control module operates within a hierarchical multiobjective framework, which imposes several constraints on the operating region, such as minimum flow and minimum speed amplitude thresholds. Three class IV heart failure (HF) cases of varying severity were simulated under rest and exercise conditions, and a comparison with other popular RBP control strategies was performed. Pump flow increases of 2.54, 1.94, and 1.15 L/min were achieved for the three HF cases, from rest to exercise. Compared with constant speed control, this represents a relative flow change of 30.3, 19.8, and -15.4%, respectively. Simulations of the proposed control algorithm exhibited the effective intervention of each constraint, resulting in an improved flow response and the maintenance of a safe operating condition, compared with other control modes.

  2. Problems with conventional vibration measurements by detection of cavitation operating of centrifugal pumps

    NASA Astrophysics Data System (ADS)

    Farkas, István; Pandula, Zoltán

    2006-06-01

    In the piping systems carrying fluids the phenomenon of cavitation may occur in a number of places. It is generated where the local pressure drops below the saturated vapour pressure. In various piping systems cavitation takes place in pumps, in cut-off fittings, regulator fittings, etc. In most cases it is detrimental. Cavitation affects the environment through noise- and vibration-related effects apart from causing physical damage of the boundary surfaces of the flow. In today's light construction buildings the vibrations may easily diffuse and this may also damage the machines and the equipment inside. Harmful vibrations arising due to cavitation may severely damage the machines, and influence their operation in a negative way. In hydraulic systems pumps are critical elements from cavitation point of view, since damage may appear in the pump on its inlet side.

  3. Microfabricated electrolysis pump system for isolating rare cells in blood

    NASA Astrophysics Data System (ADS)

    Furdui, Vasile I.; Kariuki, James K.; Jed Harrison, D.

    2003-07-01

    An integrated system for immunomagnetic separation of rare cells from blood is presented. A micromachined device was fabricated by bonding silicon die with etched structures to a glass cover plate on which electrodes are defined. Electrolytic generation of gas from 0.50 M KNO3 (aqueous) provided pumping actuation for a device that performed the capture and purification of rare cells spiked into a 7.5 µl reconstituted blood sample. The system consisted of two pumps, a sample and a wash buffer meander reservoir, and a main channel for magnetic field trapping of rare cells captured by antibody-coated magnetic beads. A maximum pumping rate of 1.4 +/- 0.1 µl min-1 was obtained at a current of 180 µA, and the maximum blood sample volume delivered to the capture bed was 6.5-7 µl. The trapped cells could be washed with the buffer from the second pump and then delivered to the exit port of the chip after removing the magnetic field.

  4. Clinical laboratory comparison of lysis-centrifugation and BACTEC radiometric blood culture techniques.

    PubMed

    McLaughlin, J C; Hamilton, P; Scholes, J V; Bartlett, R C

    1983-11-01

    The lysis-centrifugation technique (ISOLATOR; E. I. du Pont de Nemours & Co., Wilmington, Del.) and the radiometric blood culture technique (BACTEC; Johnston Laboratories, Inc., Cockeysville, Md.) were compared on 1,000 blood cultures. A total of 16 ml of blood was distributed: 8 ml into an ISOLATOR 7.5 microbial tube and 4 ml each into BACTEC 7C and 8B bottles. The concentrate from the ISOLATOR tubes was inoculated under a laminar-flow hood onto two sheep blood agar plates (one incubated in CO2 and one incubated anaerobically), one chocolate agar plate, and one brain heart infusion agar plate. Of 91 blood specimens obtained that yielded clinically significant organisms, 52 were positive by both systems, 27 were positive by the ISOLATOR system only, and 12 were positive by the BACTEC system only. From the positive blood specimens, 97 clinically significant organisms were isolated: 57 by both systems, 27 by the ISOLATOR system only, and 13 by the BACTEC system only. Of the 57 organisms detected by both systems, 28 were detected simultaneously, 13 were detected earlier by the ISOLATOR system, and 16 were detected earlier by the BACTEC system. Isolated colonies were obtained earlier by the ISOLATOR system in 40 cases and by the BACTEC system in 5 cases. Organisms determined to be contaminants by thorough chart review were isolated from 138 ISOLATOR tubes. In 98 instances, these were represented by one colony of Staphylococcus epidermidis, alpha-hemolytic streptococci, or diphtheroids. The ability to determine CFU per milliliter with the ISOLATOR system did not help differentiate clinically significant organisms from contaminants.

  5. Validation of high-resolution gamma-ray computed tomography for quantitative gas holdup measurements in centrifugal pumps

    NASA Astrophysics Data System (ADS)

    Bieberle, André; Schäfer, Thomas; Neumann, Martin; Hampel, Uwe

    2015-09-01

    In this article, the capability of high-resolution gamma-ray computed tomography (HireCT) for quantitative gas-liquid phase distribution measurements in commercially available industrial pumps is experimentally investigated. The object of interest thereby operates under two-phase flow conditions. HireCT System comprises a collimated 137Cs isotopic source, a radiation detector arc with a multi-channel signal processing unit, and a rotary unit enabling CT scans of objects with diameters of up to 700 mm. The accuracy of gas holdup measurements was validated on a sophisticated modular test mockup replicating defined gas-liquid distributions, which are expected in impeller chambers of industrial centrifugal pumps under two-phase operation. Stationary as well as rotation-synchronized CT scanning techniques have been analyzed, which are both used to obtain sharply resolved gas phase distributions in rotating structures as well as non-rotating zones. A measuring accuracy of better than 1% absolute for variously distributed static gas holdups in the rotating frame has been verified with the modular test mockup using HireCT.

  6. A new design and computational fluid dynamics study of an implantable axial blood pump.

    PubMed

    Koochaki, Mojtaba; Niroomand-Oscuii, Hanieh

    2013-12-01

    Considering small thoracic space, using implantable ventricular assist device requires reduction in a pump size. Among many available blood pumps, axial blood pumps have attracted greatly because of their small size. In this article, a new miniature axial blood pump has been designed and studied which can be easily implanted in the human body. In this design, the pump overall length decreased by a little increasing in the pump diameter, and new blade geometry is used to produce a streamlined, idealized, and nonobstructing blood flow path in the pump. By means of computational fluid dynamic, the flow pattern through the pump has been predicted and overall pump performance and efficiency has been computed. Also, to ensure a reliable VAD design, two methods for checking wall shear stress were used to confirm that this pump wouldn't cause serious blood damage.

  7. Survey of blood pump diaphragm damage in the NIPRO-ventricular assist device.

    PubMed

    Kashiwa, Koichi; Nishimura, Takashi; Nakahata, Aoi; Momose, Naoki; Umeda, Chinori; Kubo, Hitoshi; Tamai, Hisayoshi; Kinugawa, Koichiro; Adachi, Hideo; Yamaguchi, Atsushi; Yambe, Tomoyuki; Katohgi, Toshiyuki; Kyo, Shunei; Ono, Minoru

    2012-12-01

    We surveyed the incidence of blood pump diaphragm damage (rupture or crack) in the NIPRO-ventricular assist device (VAD). In the cases in which rupture or suspected blood pump crack was detected, we disassembled the pumps to visually check the condition of the diaphragm after replacement or use. Of 366 blood pumps surveyed, diaphragm damage was observed in 2.7 %. The duration of use of the blood pumps with diaphragm damage was significantly longer than that of pumps without damage. The incidence of diaphragm damage increased with longer duration of use. On the basis of these findings, blood pump diaphragm damage in the NIPRO-VAD may be associated with duration of use. However, some blood pumps were used for prolonged periods without diaphragm damage. All blood pumps with damage had a crack in the diaphragm on the air chamber side near the diaphragm-housing (D-H) junction. Cracks were not found in any specific part of the diaphragm. In blood pumps with diaphragm rupture, the crack had a through-hole reaching the blood-contacting surface. Although we were unable to identify the causes of the cracks, it is suggested that when a crack appears in the diaphragm it will gradually expand and eventually lead to rupture. If a crack is detected in a blood pump, we advocate replacing the pump before it grows. When the NIPRO-VAD is used, it is necessary to keep in mind that blood pump diaphragm damage may occur.

  8. Identification and classification of physiologically significant pumping states in an implantable rotary blood pump.

    PubMed

    Karantonis, Dean M; Lovell, Nigel H; Ayre, Peter J; Mason, David G; Cloherty, Shaun L

    2006-09-01

    In a clinical setting it is necessary to control the speed of rotary blood pumps used as left ventricular assist devices to prevent possible severe complications associated with over- or underpumping. The hypothesis is that by using only the noninvasive measure of instantaneous pump impeller speed to assess flow dynamics, it is possible to detect physiologically significant pumping states (without the need for additional implantable sensors). By varying pump speed in an animal model, five such states were identified: regurgitant pump flow, ventricular ejection (VE), nonopening of the aortic valve over the cardiac cycle (ANO), and partial collapse (intermittent and continuous) of the ventricle wall (PVC-I and PVC-C). These states are described in detail and a strategy for their noninvasive detection has been developed and validated using (n = 6) ex vivo porcine experiments. Employing a classification and regression tree, the strategy was able to detect pumping states with a high degree of sensitivity and specificity: state VE-99.2/100.0% (sensitivity/specificity); state ANO-100.0/100.0%; state PVC-I- 95.7/91.2%; state PVC-C-69.7/98.7%. With a simplified binary scheme differentiating suction (PVC-I, PVC-C) and nonsuction (VE, ANO) states, both such states were detected with 100% sensitivity.

  9. Novel method to determine instantaneous blood volume in pulsatile blood pump using electrical impedance.

    PubMed

    Sasaki, E; Nakatani, T; Taenaka, Y; Takano, H; Hirose, H

    1994-08-01

    A novel real-time volumetric method was developed for a pulsatile pump. This method, the impedance method, used electrical impedance change in the blood chamber according to volume change while pumping. This method was evaluated with two kinds of air-driven diaphragm pumps. During in vitro tests, the impedance method indicated real-time volume change, and there was excellent correlation between computed stroke volume with the impedance method and measured stroke volume with the electromagnetic flowmeter. In chronic animal tests with goats and in a clinical case, the impedance method measured pump output accurately, and it detected diaphragm motion in real-time. In addition, excellent durability was seen. Full-fill to full-empty drive was realized accurately with this method. Application of the impedance method was easy, and it did not deteriorate native antithrombogencity of the pump. The impedance method is practical and useful to estimate the pumping condition of a pulsatile blood pump, especially a diaphragm pump. This method would be useful in clinical application.

  10. Optimization of a single-stage double-suction centrifugal pump

    NASA Astrophysics Data System (ADS)

    Škerlavaj, A.; Morgut, M.; Jošt, D.; Nobile, E.

    2017-01-01

    In this study, the objective of the optimization of a double-suction pump is the maximization of its hydraulic efficiency. The optimization is performed, by means of the modeFRONTIER optimization platform, in steps. At first, by means of a DOE (Design of Experiments) strategy, the design space is explored, using a parameterized CAD representation of the pump. Suitable metamodels (surrogates or Response Surfaces), which represent an economical alternative to the more expensive 3D CFD model, are built and tested. Among different metamodels, the evolutionary design, radial basis function and the stepwise regression models seem to be the most promising ones. Finally, the stepwise regression model, trained on a set of 200 designs and constructed with only five the most influential input design parameters, was chosen as a potentially applicable metamodel.

  11. Part-load flow and hydraulic stability of centrifugal pumps. Final report

    SciTech Connect

    Guelich, J.F.; Egger, R.

    1992-03-01

    Unscheduled outages and deratings caused by problems with feed pumps cost utilities an estimated $460 million in replacement power costs 1985. Vibrations and pressure pulsations caused by the flow separation at partload operation are among the leading causes of feed pump failures. To reduce or avoid such failures, the flow mechanisms responsible for hydraulic instabilities must be understood. To increase this understanding was one of the main objectives of the hydraulic investigations carried out under the present research project and described in this report. A large number of parameters influencing the hydraulic performance and the stability of the head capacity characteristics have been investigated and guidelines have been derived for the selection of design parameters for impellers, diffusers, and volutes.

  12. The Use of Centrifugal Flow Pumps in a Model of Experimental Right Heart Failure

    DTIC Science & Technology

    1988-12-01

    clinical situations such as right ventricular in- farction, pulmonary hypertension , and pulmonary embolism. O"" 147 E0ION OF I NOV 6S IS OBSOLETE SD C...study was to an- pulmonary hypertension , and pulmonary em- swer three questions: Can ischemic right bolism. - ventricular failure be induced...proximal 4 pulmonar . a rtc r., S3 AL B2 gation baseline values were reached for the 2 84 values outlined earlier. The pump was then turned off and the