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Sample records for bypass model turbofan

  1. The Effect of Bypass Nozzle Exit Area on Fan Aerodynamic Performance and Noise in a Model Turbofan Simulator

    NASA Technical Reports Server (NTRS)

    Hughes, Christopher E.; Podboy, Gary, G.; Woodward, Richard P.; Jeracki, Robert, J.

    2013-01-01

    The design of effective new technologies to reduce aircraft propulsion noise is dependent on identifying and understanding the noise sources and noise generation mechanisms in the modern turbofan engine, as well as determining their contribution to the overall aircraft noise signature. Therefore, a comprehensive aeroacoustic wind tunnel test program was conducted called the Fan Broadband Source Diagnostic Test as part of the NASA Quiet Aircraft Technology program. The test was performed in the anechoic NASA Glenn 9- by 15-Foot Low Speed Wind Tunnel using a 1/5 scale model turbofan simulator which represented a current generation, medium pressure ratio, high bypass turbofan aircraft engine. The investigation focused on simulating in model scale only the bypass section of the turbofan engine. The test objectives were to: identify the noise sources within the model and determine their noise level; investigate several component design technologies by determining their impact on the aerodynamic and acoustic performance of the fan stage; and conduct detailed flow diagnostics within the fan flow field to characterize the physics of the noise generation mechanisms in a turbofan model. This report discusses results obtained for one aspect of the Source Diagnostic Test that investigated the effect of the bypass or fan nozzle exit area on the bypass stage aerodynamic performance, specifically the fan and outlet guide vanes or stators, as well as the farfield acoustic noise level. The aerodynamic performance, farfield acoustics, and Laser Doppler Velocimeter flow diagnostic results are presented for the fan and four different fixed-area bypass nozzle configurations. The nozzles simulated fixed engine operating lines and encompassed the fan stage operating envelope from near stall to cruise. One nozzle was selected as a baseline reference, representing the nozzle area which would achieve the design point operating conditions and fan stage performance. The total area change from

  2. Acoustic Performance of Novel Fan Noise Reduction Technologies for a High Bypass Model Turbofan at Simulated Flights Conditions

    NASA Technical Reports Server (NTRS)

    Elliott, David M.; Woodward, Richard P.; Podboy, Gary G.

    2010-01-01

    Two novel fan noise reduction technologies, over the rotor acoustic treatment and soft stator vane technologies, were tested in an ultra-high bypass ratio turbofan model in the NASA Glenn Research Center s 9- by 15-Foot Low-Speed Wind Tunnel. The performance of these technologies was compared to that of the baseline fan configuration, which did not have these technologies. Sideline acoustic data and hot film flow data were acquired and are used to determine the effectiveness of the various treatments. The material used for the over the rotor treatment was foam metal and two different types were used. The soft stator vanes had several internal cavities tuned to target certain frequencies. In order to accommodate the cavities it was necessary to use a cut-on stator to demonstrate the soft vane concept.

  3. Jet noise from ultrahigh bypass turbofan engines

    NASA Astrophysics Data System (ADS)

    Posey, Joe W.; Norum, Thomas D.; Brown, Martha C.; Bhat, Thonse R. S.

    2002-05-01

    Modern commercial jet transport aircraft are powered by turbofan engines. Thrust from a turbofan engine is derived in part from the exhaust of a ducted fan, which may or may not be mixed with the core exhaust before exiting the nacelle. The historical trend has been toward ever higher bypass ratios (BPRs). The BPR is the ratio of air mass passing through the fan to that going through the core. The higher BPR engines can be more efficient and quieter. In general, a higher BPR results in lower average exhaust velocities and less jet noise. In order to address a scarcity of noise data for BPRs greater than 6, an extensive database collection effort was undertaken using the Jet Engine Simulator in NASA Langley's Low Speed Aeroacoustic Wind Tunnel. Forward flight simulations of Mach 0.1, 0.2, and 0.28 were used with BPRs of 5, 8, 11, and 14. Data was taken over the entire operating line of the simulated engines along with parametric deviations to provide a complete set of sensitivity measurements. The results will be used to develop an empirical jet noise prediction capability for ultrahigh bypass engines.

  4. Effects of Test Cell Recirculation on High-Bypass Turbofan Engines during Simulated Altitude Tests

    DTIC Science & Technology

    1986-08-01

    methods used to describe and correct for test cell recirculation have led to this investigation, which is in line with the objectives previously stated...between pressure profiles on the cell wall and those on the model surfaces, which is in line with previous observations. Removal of the diffuser...AEDC-TR-85-55 , , . ’ . . . .L Effects of Test Cell Recirculation on High-Bypass Turbofan Engines During Simulated Altitude Tests OCT 0 9

  5. Extended frequency turbofan model

    NASA Technical Reports Server (NTRS)

    Mason, J. R.; Park, J. W.; Jaekel, R. F.

    1980-01-01

    The fan model was developed using two dimensional modeling techniques to add dynamic radial coupling between the core stream and the bypass stream of the fan. When incorporated into a complete TF-30 engine simulation, the fan model greatly improved compression system frequency response to planar inlet pressure disturbances up to 100 Hz. The improved simulation also matched engine stability limits at 15 Hz, whereas the one dimensional fan model required twice the inlet pressure amplitude to stall the simulation. With verification of the two dimensional fan model, this program formulated a high frequency F-100(3) engine simulation using row by row compression system characteristics. In addition to the F-100(3) remote splitter fan, the program modified the model fan characteristics to simulate a proximate splitter version of the F-100(3) engine.

  6. High Bypass Turbofan Component Development. Phase II. Detailed Design.

    DTIC Science & Technology

    1979-08-01

    Selecting Blade Thickness for Bird Strike 46 27. Method for Selecting Blade Airfoil Attachment 49 AIRCRAF ENGINE GROUP IV GENERAL ELECTRIC COMPANY...reserves, the replacement aircraft must have a fuel efficient engine as the propulsion system, i. e., * modern turbofan engine . Technology in the large... turbofan engines has been well demonstrated, but little has been done in the size applicable to a twin- engine primary trainer aircraft . Today, there is

  7. Turbofan Duct Propagation Model

    NASA Technical Reports Server (NTRS)

    Lan, Justin H.; Posey, Joe W. (Technical Monitor)

    2001-01-01

    The CDUCT code utilizes a parabolic approximation to the convected Helmholtz equation in order to efficiently model acoustic propagation in acoustically treated, complex shaped ducts. The parabolic approximation solves one-way wave propagation with a marching method which neglects backwards reflected waves. The derivation of the parabolic approximation is presented. Several code validation cases are given. An acoustic lining design process for an example aft fan duct is discussed. It is noted that the method can efficiently model realistic three-dimension effects, acoustic lining, and flow within the computational capabilities of a typical computer workstation.

  8. Preliminary Study on Acoustic Detection of Faults Experienced by a High-Bypass Turbofan Engine

    NASA Technical Reports Server (NTRS)

    Boyle, Devin K.

    2014-01-01

    The vehicle integrated propulsion research (VIPR) effort conducted by NASA and several partners provided an unparalleled opportunity to test a relatively low TRL concept regarding the use of far field acoustics to identify faults occurring in a high bypass turbofan engine. Though VIPR Phase II ground based aircraft installed engine testing wherein a multitude of research sensors and methods were evaluated, an array of acoustic microphones was used to determine the viability of such an array to detect failures occurring in a commercially representative high bypass turbofan engine. The failures introduced during VIPR testing included commanding the engine's low pressure compressor (LPC) exit and high pressure compressor (HPC) 14th stage bleed values abruptly to their failsafe positions during steady state

  9. Turbine bypass turbofan with mid-turbine reingestion and method of operating the same

    SciTech Connect

    Klees, G.W.

    1984-03-13

    A supersonic two spool turbofan engine is disclosed capable not only of developing sufficient power to accelerate up to supersonic cruise and maintain efficient operation at supersonic cruise, but also arranged to cruise at subsonic velocities with a relatively low specific fuel consumption. The engine is provided with a variable bypass passageway downstream of the compressor. Flow into the bypass passageway is controlled so that during low power setting the bypass passageway is closed so that all the gaseous flow is directed through the turbine. During higher power settings, the bypass passageway is opened to the extent that a selected portion of the gaseous flow is directed through the bypass passageway to bypass the first stage of the turbine section so that the corrected flow to the first turbine stage remains substantially constant for high and low power setting of the engine. The bypass flow is then directed into the area between the first and second turbine to combine with the gaseous flow passing through the first turbine and pass through the second turbine.

  10. Analytical evaluation of the impact of broad specification fuels on high bypass turbofan engine combustors

    NASA Technical Reports Server (NTRS)

    Taylor, J. R.

    1979-01-01

    Six conceptual combustor designs for the CF6-50 high bypass turbofan engine and six conceptual combustor designs for the NASA/GE E3 high bypass turbofan engine were analyzed to provide an assessment of the major problems anticipated in using broad specification fuels in these aircraft engine combustion systems. Each of the conceptual combustor designs, which are representative of both state-of-the-art and advanced state-of-the-art combustion systems, was analyzed to estimate combustor performance, durability, and pollutant emissions when using commercial Jet A aviation fuel and when using experimental referee board specification fuel. Results indicate that lean burning, low emissions double annular combustor concepts can accommodate a wide range of fuel properties without a serious deterioration of performance or durability. However, rich burning, single annular concepts would be less tolerant to a relaxation of fuel properties. As the fuel specifications are relaxed, autoignition delay time becomes much smaller which presents a serious design and development problem for premixing-prevaporizing combustion system concepts.

  11. Aerodynamic Performance of Scale-Model Turbofan Outlet Guide Vanes Designed for Low Noise

    NASA Technical Reports Server (NTRS)

    Hughes, Christopher E.

    2001-01-01

    The design of effective new technologies to reduce aircraft propulsion noise is dependent on an understanding of the noise sources and noise generation mechanisms in the modern turbofan engine. In order to more fully understand the physics of noise in a turbofan engine, a comprehensive aeroacoustic wind tunnel test programs was conducted called the 'Source Diagnostic Test.' The text was cooperative effort between NASA and General Electric Aircraft Engines, as part of the NASA Advanced Subsonic Technology Noise Reduction Program. A 1/5-scale model simulator representing the bypass stage of a current technology high bypass ratio turbofan engine was used in the test. The test article consisted of the bypass fan and outlet guide vanes in a flight-type nacelle. The fan used was a medium pressure ratio design with 22 individual, wide chord blades. Three outlet guide vane design configurations were investigated, representing a 54-vane radial Baseline configuration, a 26-vane radial, wide chord Low Count configuration and a 26-vane, wide chord Low Noise configuration with 30 deg of aft sweep. The test was conducted in the NASA Glenn Research Center 9 by 15-Foot Low Speed Wind Tunnel at velocities simulating the takeoff and approach phases of the aircraft flight envelope. The Source Diagnostic Test had several acoustic and aerodynamic technical objectives: (1) establish the performance of a scale model fan selected to represent the current technology turbofan product; (2) assess the performance of the fan stage with each of the three distinct outlet guide vane designs; (3) determine the effect of the outlet guide vane configuration on the fan baseline performance; and (4) conduct detailed flowfield diagnostic surveys, both acoustic and aerodynamic, to characterize and understand the noise generation mechanisms in a turbofan engine. This paper addresses the fan and stage aerodynamic performance results from the Source Diagnostic Test.

  12. A brief study of the effects of turbofan-engine bypass ratio on short and long haul cruise aircraft

    NASA Technical Reports Server (NTRS)

    Keith, A. L., Jr.

    1975-01-01

    A brief study of the effects of turbofan-engine bypass ratio on Breguet cruise range and take-off distance for subsonic cruise aircraft showed significant differences between short- and long-haul aircraft designs. Large thrust lapse rates at high bypass ratios caused severe reductions in cruise range for short-haul aircraft because of increases in propulsion system weight. Long-haul aircraft, with a higher fuel fraction (ratio of propulsion weight plus total fuel weight to gross take-off weight), are less sensitive to propulsion-system weight and, accordingly, were not significantly affected by bypass-ratio variations. Both types of aircraft have shorter take-off distances at higher bypass ratios because of higher take-off thrust-weight ratios.

  13. The Potential Benefits of Advanced Casing Treatment for Noise Attenuation in Utra-High Bypass Ratio Turbofan Engines

    NASA Technical Reports Server (NTRS)

    Elliott, David

    2007-01-01

    In order to increase stall margin in a high-bypass ratio turbofan engine, an advanced casing treatment was developed that extracted a small amount of flow from the casing behind the fan and injected it back in front of the fan. Several different configurations of this casing treatment were designed by varying the distance of the extraction and injection points, as well as varying the amount of flow. These casing treatments were tested on a 55.9 cm (22 in.) scale model of the Pratt & Whitney Advanced Ducted Propulsor in the NASA Glenn 9 by 15 Low Speed Wind Tunnel. While all of the casing treatment configurations showed the expected increase in stall margin, a few of the designs showed a potential noise benefit for certain engine speeds. This paper will show the casing treatments and the results of the testing as well as propose further research in this area. With better prediction and design techniques, future casing treatment configurations could be developed that may result in an optimized casing treatment that could conceivably reduce the noise further.

  14. Experimental clean combustor program, phase 3: Noise measurement addendum. [CF6-50 high bypass turbofan engine noise

    NASA Technical Reports Server (NTRS)

    Doyle, V. L.

    1978-01-01

    The acoustic characteristics of the double annular combustor in a CF6-50 high bypass turbofan engine were investigated. Internal fluctuating pressure measurements were made in the combustor region and in the core exhaust. The transmission loss across the turbine and nozzle was determined from the measurements and compared to previous component results and present theory. The primary noise source location in the combustor was investigated. Spectral comparisons of test rig results were made with the engine results. The measured overall power level was compared with component and engine correlating parameters.

  15. Enhanced Fan Noise Modeling for Turbofan Engines

    NASA Technical Reports Server (NTRS)

    Krejsa, Eugene A.; Stone, James R.

    2014-01-01

    This report describes work by consultants to Diversitech Inc. for the NASA Glenn Research Center (GRC) to revise the fan noise prediction procedure based on fan noise data obtained in the 9- by 15 Foot Low-Speed Wind Tunnel at GRC. The purpose of this task is to begin development of an enhanced, analytical, more physics-based, fan noise prediction method applicable to commercial turbofan propulsion systems. The method is to be suitable for programming into a computational model for eventual incorporation into NASA's current aircraft system noise prediction computer codes. The scope of this task is in alignment with the mission of the Propulsion 21 research effort conducted by the coalition of NASA, state government, industry, and academia to develop aeropropulsion technologies. A model for fan noise prediction was developed based on measured noise levels for the R4 rotor with several outlet guide vane variations and three fan exhaust areas. The model predicts the complete fan noise spectrum, including broadband noise, tones, and for supersonic tip speeds, combination tones. Both spectra and directivity are predicted. Good agreement with data was achieved for all fan geometries. Comparisons with data from a second fan, the ADP fan, also showed good agreement.

  16. Noise predictions of a high bypass turbofan engine using the Lockheed Near-Field Noise Prediction Program

    NASA Technical Reports Server (NTRS)

    Rawls, J. W., Jr.

    1986-01-01

    The prediction of engine noise during cruise using the Near-Field Noise Prediction Program developed by Lockheed is examined. Test conditions were established which simulate the operation of a high bypass turbofan engine under a wide range of operating conditions. These test conditions include variations in altitude, flight Mach number and thrust setting. Based on the results of noise prediction made using the Lockheed program, an evaluation of the impact of these test conditions on the overall sound pressure level(OASPL)and the one-third octave band spectra is made. An evaluation of the sensitivity of flight condition parameters is also made. The primary noise source from a high bypass turbofan was determined to be fan broadband shock noise. This noise source can be expected to be present during normal cruising conditions. When present, fan broadband shock noise usually dominates at all frequencies and all directivity angles. Other noise sources of importance are broadband shock noise from the primary jet, fan noise, fan mixing noise and turbine noise.

  17. Modeling Commercial Turbofan Engine Icing Risk With Ice Crystal Ingestion

    NASA Technical Reports Server (NTRS)

    Jorgenson, Philip C. E.; Veres, Joseph P.

    2013-01-01

    The occurrence of ice accretion within commercial high bypass aircraft turbine engines has been reported under certain atmospheric conditions. Engine anomalies have taken place at high altitudes that have been attributed to ice crystal ingestion, partially melting, and ice accretion on the compression system components. The result was degraded engine performance, and one or more of the following: loss of thrust control (roll back), compressor surge or stall, and flameout of the combustor. As ice crystals are ingested into the fan and low pressure compression system, the increase in air temperature causes a portion of the ice crystals to melt. It is hypothesized that this allows the ice-water mixture to cover the metal surfaces of the compressor stationary components which leads to ice accretion through evaporative cooling. Ice accretion causes a blockage which subsequently results in the deterioration in performance of the compressor and engine. The focus of this research is to apply an engine icing computational tool to simulate the flow through a turbofan engine and assess the risk of ice accretion. The tool is comprised of an engine system thermodynamic cycle code, a compressor flow analysis code, and an ice particle melt code that has the capability of determining the rate of sublimation, melting, and evaporation through the compressor flow path, without modeling the actual ice accretion. A commercial turbofan engine which has previously experienced icing events during operation in a high altitude ice crystal environment has been tested in the Propulsion Systems Laboratory (PSL) altitude test facility at NASA Glenn Research Center. The PSL has the capability to produce a continuous ice cloud which are ingested by the engine during operation over a range of altitude conditions. The PSL test results confirmed that there was ice accretion in the engine due to ice crystal ingestion, at the same simulated altitude operating conditions as experienced previously in

  18. Testing and Performance Verification of a High Bypass Ratio Turbofan Rotor in an Internal Flow Component Test Facility

    NASA Technical Reports Server (NTRS)

    VanZante, Dale E.; Podboy, Gary G.; Miller, Christopher J.; Thorp, Scott A.

    2009-01-01

    A 1/5 scale model rotor representative of a current technology, high bypass ratio, turbofan engine was installed and tested in the W8 single-stage, high-speed, compressor test facility at NASA Glenn Research Center (GRC). The same fan rotor was tested previously in the GRC 9x15 Low Speed Wind Tunnel as a fan module consisting of the rotor and outlet guide vanes mounted in a flight-like nacelle. The W8 test verified that the aerodynamic performance and detailed flow field of the rotor as installed in W8 were representative of the wind tunnel fan module installation. Modifications to W8 were necessary to ensure that this internal flow facility would have a flow field at the test package that is representative of flow conditions in the wind tunnel installation. Inlet flow conditioning was designed and installed in W8 to lower the fan face turbulence intensity to less than 1.0 percent in order to better match the wind tunnel operating environment. Also, inlet bleed was added to thin the casing boundary layer to be more representative of a flight nacelle boundary layer. On the 100 percent speed operating line the fan pressure rise and mass flow rate agreed with the wind tunnel data to within 1 percent. Detailed hot film surveys of the inlet flow, inlet boundary layer and fan exit flow were compared to results from the wind tunnel. The effect of inlet casing boundary layer thickness on fan performance was quantified. Challenges and lessons learned from testing this high flow, low static pressure rise fan in an internal flow facility are discussed.

  19. Optimal design and installation of ultra high bypass ratio turbofan nacelle

    NASA Astrophysics Data System (ADS)

    Savelyev, Andrey; Zlenko, Nikolay; Matyash, Evgeniy; Mikhaylov, Sergey; Shenkin, Andrey

    2016-10-01

    The paper is devoted to the problem of designing and optimizing the nacelle of turbojet bypass engine with high bypass ratio and high thrust. An optimization algorithm EGO based on development of surrogate models and the method for maximizing the probability of improving the objective function has been used. The designing methodology has been based on the numerical solution of the Reynolds equations system. Spalart-Allmaras turbulence model has been chosen for RANS closure. The effective thrust losses has been uses as an objective function in optimizing the engine nacelle. As a result of optimization, effective thrust has been increased by 1.5 %. The Blended wing body aircraft configuration has been studied as a possible application. Two variants of the engine layout arrangement have been considered. It has been shown that the power plant changes the pressure distribution on the aircraft surface. It results in essential diminishing the configuration lift-drag ratio.

  20. Investigation of performance deterioration of the CF6/JT9D, high-bypass ratio turbofan engines

    NASA Technical Reports Server (NTRS)

    Ziemianski, J. A.; Mehalic, C. M.

    1980-01-01

    The aircraft energy efficiency program within NASA is developing technology required to improve the fuel efficiency of commercial subsonic transport aricraft. One segment of this program includes engine diagnostics which is directed toward determining the sources and causes of performance deterioration in the Pratt and Whitney Aircraft JT9D and General Electric CF6 high-bypass ratio turbofan engines and developing technology for minimizing the performance losses. Results of engine performance deterioration investigations based on historical data, special engine tests, and specific tests to define the influence of flight loads and component clearances on performance are presented. The results of analysis of several damage mechanisms that contribute to performance deterioration such as blade tip rubs, airfoil surface roughness and erosion, and thermal distortion are also included. The significance of these damage mechanisms on component and overall engine performance is discussed.

  1. Conceptual study of an advanced supersonic technology transport (AST-107) for transpacific range using low-bypass-ratio turbofan engines

    NASA Technical Reports Server (NTRS)

    Morris, S. J., Jr.; Foss, W. E., Jr.; Neubauer, M. J., Jr.

    1980-01-01

    An advanced supersonic technology configuration concept designated the AST-107, using a low bypass ratio turbofan engine, is described and analyzed. The aircraft had provisions for 273 passengers arranged five abreast. The cruise Mach number was 2.62. The mission range for the AST-107 was 8.48 Mm (4576 n.mi.) and an average lift drag ratio of 9.15 during cruise was achieved. The available lateral control was not sufficient for the required 15.4 m/s (30 kt) crosswind landing condition, and a crosswind landing gear or a significant reduction in dihedral effect would be necessary to meet this requirement. The lowest computed noise levels, including a mechanical suppressor noise reduction of 3 EPNdB at the flyover and sideline monitoring stations, were 110.3 EPNdB (sideline noise), 113.1 EPNdB (centerline noise) and 110.5 EPNdB (approach noise).

  2. CFD simulations of the flow control performance applied for inlet of low drag high-bypass turbofan engine at cross flow regimes

    NASA Astrophysics Data System (ADS)

    Kursakov, I. A.; Kazhan, E. V.; Lysenkov, A. V.; Savelyev, A. A.

    2016-10-01

    Paper describes the optimization procedure for low cruise drag inlet of high-bypass ratio turbofan engine (HBRE). The critical cross-flow velocity when the flow separation on the lee side of the inlet channel occurs is determined. The effciency of different flow control devices used to improve the flow parameters at inlet section cross flow regime is analyzed. Boundary layer suction, bypass slot and vortex generators are considered. It is shown that flow control devices enlarge the stability range of inlet performance at cross flow regimes.

  3. 75 FR 32262 - Airworthiness Directives; CFM International, S.A. Models CFM56-3 and -3B Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-08

    ..., S.A. Models CFM56-3 and -3B Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT... International, S.A. models CFM56-3 and -3B turbofan engines. This AD requires initial and repetitive inspections... CFM International, S.A. models CFM56-3 and -3B turbofan engines. We published the proposed AD in...

  4. Turbofan engine with a low pressure turbine driven supercharger in a bypass duct operated by a fuel rich combustor and an afterburner

    NASA Technical Reports Server (NTRS)

    Bartos, James W. (Inventor)

    1999-01-01

    A multiple bypass turbofan engine includes a core Brayton Cycle gas generator with a fuel rich burning combustor and is provided with a variable supercharged bypass duct around the gas generator with a supercharging means in the supercharged bypass duct powered by a turbine not mechanically connected to the gas generator. The engine further includes a low pressure turbine driven forward fan upstream and forward of an aft fan and drivingly connected to a low pressure turbine by a low pressure shaft, the low pressure turbine being aft of and in serial flow communication with the core gas generator. A fan bypass duct is disposed radially outward of the core engine assembly and has first and second inlets disposed between the forward and aft fans. An inlet duct having an annular duct wall is disposed radially inward of the bypass duct and connects the second inlet to the bypass duct. A supercharger means for compressing air is drivingly connected to the low pressure turbine and is disposed in the inlet duct. A secondary combustor or augmentor is disposed in an exhaust duct downstream of and in fluid flow communication with the bypass duct and the gas generator.

  5. Effect of combined pressure and temperature distortion orientation on high-bypass-ratio turbofan engine stability

    NASA Technical Reports Server (NTRS)

    Soeder, R. H.; Mehalic, C. M.

    1984-01-01

    Total-temperature, static-pressure and total-pressure distributions were measured in the inlet duct upstream of the engine inlet and within the fan and compressor of a YTF34 turbofan engine. Free-stream and boundary layer yaw angle variations were measured between a rotable screen assembly and the engine inlet. Total pressure distortions were generated using three 180 deg extent screens and total temperature distortions were generated using a rotatable hydrogen burner. Reynolds number index upstream of the rotatable screen assembly was maintained at 0.5 (based on the undistorted sectors at station 1, the inlet flow measuring station). The engine mechanical fan speed at sea level condition was rated at 7005 rpm. The engine was tested at a corrected fan speed of 90 percent of rated condition. Yaw angle increased between the rotatable screen assembly and the engine inlet. The largest variation in free-stream and boundary layer yaw angle occurs when the combined distortions are 180 deg out-of-phase. Static-pressure distortion increased exponentially as flow approached the engine. Total-pressure distortions were attenuated between the engine inlet and the compressor exit. Total-temperature distortion persisted through the compressor for all four combined distortions investigated.

  6. Digital computer program for generating dynamic turbofan engine models (DIGTEM)

    NASA Technical Reports Server (NTRS)

    Daniele, C. J.; Krosel, S. M.; Szuch, J. R.; Westerkamp, E. J.

    1983-01-01

    This report describes DIGTEM, a digital computer program that simulates two spool, two-stream turbofan engines. The turbofan engine model in DIGTEM contains steady-state performance maps for all of the components and has control volumes where continuity and energy balances are maintained. Rotor dynamics and duct momentum dynamics are also included. Altogether there are 16 state variables and state equations. DIGTEM features a backward-differnce integration scheme for integrating stiff systems. It trims the model equations to match a prescribed design point by calculating correction coefficients that balance out the dynamic equations. It uses the same coefficients at off-design points and iterates to a balanced engine condition. Transients can also be run. They are generated by defining controls as a function of time (open-loop control) in a user-written subroutine (TMRSP). DIGTEM has run on the IBM 370/3033 computer using implicit integration with time steps ranging from 1.0 msec to 1.0 sec. DIGTEM is generalized in the aerothermodynamic treatment of components.

  7. Acoustic Performance of an Advanced Model Turbofan in Three Aeroacoustic Test Facilities

    NASA Technical Reports Server (NTRS)

    Woodward, Richard P.; Hughes, Christopher E.

    2012-01-01

    A model advanced turbofan was acoustically tested in the NASA Glenn 9- by 15-Foot-Low-Speed Wind Tunnel (LSWT), and in two other aeroacoustic facilities. The Universal Propulsion Simulator (UPS) fan was designed and manufactured by the General Electric Aircraft Engines (GEAE) Company, and featured active core, as well as bypass, flow paths. The reference test configurations were with the metal, M4, rotor with hardwall and treated bypass flow ducts. The UPS fan was tested within an airflow at a Mach number of 0.20 (limited flow data were also acquired at a Mach number of 0.25) which is representative of aircraft takeoff and approach conditions. Comparisons were made between data acquired within the airflow (9x15 LSWT and German-Dutch Wind Tunnel (DNW)) and outside of a free jet (Boeing Low Speed Aero acoustic Facility (LSAF) and DNW). Sideline data were acquired on an 89-in. (nominal 4 fan diameters) sideline using the same microphone assembly and holder in the 9x15 LSWT and DNW facilities. These data showed good agreement for similar UPS operating conditions and configurations. Distortion of fan spectra tonal content through a free jet shear layer was documented, suggesting that in-flow acoustic measurements are required for comprehensive fan noise diagnostics. However, there was good agreement for overall sound power level (PWL) fan noise measurements made both within and outside of the test facility airflow.

  8. Installation effects of wing-mounted turbofan nacelle-pylons on a 1/17-scale, twin-engine, low-wing transport model

    NASA Technical Reports Server (NTRS)

    Pendergraft, Odis C., Jr.; Ingraldi, Anthony M.; Re, Richard J.; Kariya, Timmy T.

    1992-01-01

    A twin-engine, low-wing transport model, with a supercritical wing of aspect ratio 10.8 designed for a cruise Mach number of 0.77 and a lift coefficient of 0.55, was tested in the Langley 16-Foot Transonic Tunnel. The purpose of this test was to compare the wing-nacelle interference effects of flow-through nacelles simulating superfan engines (very high bypass ratio (BPR is approx. = 18) turbofan engines) with the wing-nacelle interference effects of current-technology turbofans (BPR is approx. = 6). Forces and moments on the complete model were measured with a strain-gage balance, and extensive external static-pressure measurements (383 orifice locations) were made on the wing, nacelles, and pylons of the model. Data were taken at Mach numbers from 0.50 to 0.80 and at model angles of attack from -4 deg to 8 deg. Test results indicate that flow-through nacelles with a very high bypass ratio can be installed on a low-wing transport model with a lower installation drag penalty than for a conventional turbofan nacelle at a design cruise Mach number of 0.77 and lift coefficient of 0.55.

  9. Research on Turbofan Engine Model above Idle State Based on NARX Modeling Approach

    NASA Astrophysics Data System (ADS)

    Yu, Bing; Shu, Wenjun

    2017-03-01

    The nonlinear model for turbofan engine above idle state based on NARX is studied. Above all, the data sets for the JT9D engine from existing model are obtained via simulation. Then, a nonlinear modeling scheme based on NARX is proposed and several models with different parameters are built according to the former data sets. Finally, the simulations have been taken to verify the precise and dynamic performance the models, the results show that the NARX model can well reflect the dynamics characteristic of the turbofan engine with high accuracy.

  10. Enhanced Core Noise Modeling for Turbofan Engines

    NASA Technical Reports Server (NTRS)

    Stone, James R.; Krejsa, Eugene A.; Clark, Bruce J.

    2011-01-01

    This report describes work performed by MTC Technologies (MTCT) for NASA Glenn Research Center (GRC) under Contract NAS3-00178, Task Order No. 15. MTCT previously developed a first-generation empirical model that correlates the core/combustion noise of four GE engines, the CF6, CF34, CFM56, and GE90 for General Electric (GE) under Contract No. 200-1X-14W53048, in support of GRC Contract NAS3-01135. MTCT has demonstrated in earlier noise modeling efforts that the improvement of predictive modeling is greatly enhanced by an iterative approach, so in support of NASA's Quiet Aircraft Technology Project, GRC sponsored this effort to improve the model. Since the noise data available for correlation are total engine noise spectra, it is total engine noise that must be predicted. Since the scope of this effort was not sufficient to explore fan and turbine noise, the most meaningful comparisons must be restricted to frequencies below the blade passage frequency. Below the blade passage frequency and at relatively high power settings jet noise is expected to be the dominant source, and comparisons are shown that demonstrate the accuracy of the jet noise model recently developed by MTCT for NASA under Contract NAS3-00178, Task Order No. 10. At lower power settings the core noise became most apparent, and these data corrected for the contribution of jet noise were then used to establish the characteristics of core noise. There is clearly more than one spectral range where core noise is evident, so the spectral approach developed by von Glahn and Krejsa in 1982 wherein four spectral regions overlap, was used in the GE effort. Further analysis indicates that the two higher frequency components, which are often somewhat masked by turbomachinery noise, can be treated as one component, and it is on that basis that the current model is formulated. The frequency scaling relationships are improved and are now based on combustor and core nozzle geometries. In conjunction with the Task

  11. Ramjet bypass duct and preburner configuration

    NASA Technical Reports Server (NTRS)

    Orlando, Robert J. (Inventor)

    1994-01-01

    A combined turbofan and ramjet aircraft engine includes a forward bypass duct which allows the engine to operate more efficiently during the turbofan mode of operation. By mounting a ramjet preburner in the forward duct and isolating this duct from the turbofan bypass air, a transition from turbofan operation to ramjet operation can take place at lower flight Mach numbers without incurring pressure losses or blockage in the turbofan bypass air.

  12. 77 FR 10952 - Airworthiness Directives; CFM International S.A. Model CFM56 Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-24

    ... Federal Register. That AD applies to CFM International S.A. CFM56-2, CFM56-3, CFM56-5A, CFM56-5B, CFM56-5C, and CFM56-7B series turbofan engines with certain part number (P/N) and serial number (SN) high....A. Model CFM56 Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION:...

  13. 75 FR 16361 - Airworthiness Directives; CFM International, S.A. Models CFM56-3 and -3B Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-01

    ..., S.A. Models CFM56-3 and -3B Turbofan Engines AGENCY: Federal Aviation Administration (FAA...), for certain CFM International, S.A. models CFM56-3 and -3B turbofan engines. That proposed AD would... inspection compliance threshold, to correct the engine model designations affected, and to clarify some...

  14. Modeling of Commercial Turbofan Engine with Ice Crystal Ingestion; Follow-On

    NASA Technical Reports Server (NTRS)

    Jorgenson, Philip C. E.; Veres, Joseph P.; Coennen, Ryan

    2014-01-01

    The occurrence of ice accretion within commercial high bypass aircraft turbine engines has been reported under certain atmospheric conditions. Engine anomalies have taken place at high altitudes that have been attributed to ice crystal ingestion, partially melting, and ice accretion on the compression system components. The result was degraded engine performance, and one or more of the following: loss of thrust control (roll back), compressor surge or stall, and flameout of the combustor. As ice crystals are ingested into the fan and low pressure compression system, the increase in air temperature causes a portion of the ice crystals to melt. It is hypothesized that this allows the ice-water mixture to cover the metal surfaces of the compressor stationary components which leads to ice accretion through evaporative cooling. Ice accretion causes a blockage which subsequently results in the deterioration in performance of the compressor and engine. The focus of this research is to apply an engine icing computational tool to simulate the flow through a turbofan engine and assess the risk of ice accretion. The tool is comprised of an engine system thermodynamic cycle code, a compressor flow analysis code, and an ice particle melt code that has the capability of determining the rate of sublimation, melting, and evaporation through the compressor flow path, without modeling the actual ice accretion. A commercial turbofan engine which has previously experienced icing events during operation in a high altitude ice crystal environment has been tested in the Propulsion Systems Laboratory (PSL) altitude test facility at NASA Glenn Research Center. The PSL has the capability to produce a continuous ice cloud which is ingested by the engine during operation over a range of altitude conditions. The PSL test results confirmed that there was ice accretion in the engine due to ice crystal ingestion, at the same simulated altitude operating conditions as experienced previously in

  15. Modeling of Commercial Turbofan Engine With Ice Crystal Ingestion: Follow-On

    NASA Technical Reports Server (NTRS)

    Jorgenson, Philip C. E.; Veres, Joseph P.; Coennen, Ryan

    2014-01-01

    The occurrence of ice accretion within commercial high bypass aircraft turbine engines has been reported under certain atmospheric conditions. Engine anomalies have taken place at high altitudes that have been attributed to ice crystal ingestion, partially melting, and ice accretion on the compression system components. The result was degraded engine performance, and one or more of the following: loss of thrust control (roll back), compressor surge or stall, and flameout of the combustor. As ice crystals are ingested into the fan and low pressure compression system, the increase in air temperature causes a portion of the ice crystals to melt. It is hypothesized that this allows the ice-water mixture to cover the metal surfaces of the compressor stationary components which leads to ice accretion through evaporative cooling. Ice accretion causes a blockage which subsequently results in the deterioration in performance of the compressor and engine. The focus of this research is to apply an engine icing computational tool to simulate the flow through a turbofan engine and assess the risk of ice accretion. The tool is comprised of an engine system thermodynamic cycle code, a compressor flow analysis code, and an ice particle melt code that has the capability of determining the rate of sublimation, melting, and evaporation through the compressor flow path, without modeling the actual ice accretion. A commercial turbofan engine which has previously experienced icing events during operation in a high altitude ice crystal environment has been tested in the Propulsion Systems Laboratory (PSL) altitude test facility at NASA Glenn Research Center. The PSL has the capability to produce a continuous ice cloud which is ingested by the engine during operation over a range of altitude conditions. The PSL test results confirmed that there was ice accretion in the engine due to ice crystal ingestion, at the same simulated altitude operating conditions as experienced previously in

  16. Analytical Modeling of Herschel-Quincke Concept Applied to Inlet Turbofan Engines

    NASA Technical Reports Server (NTRS)

    Hallez, Raphael F.; Burdisso, Ricardo A.; Gerhold, Carl H. (Technical Monitor)

    2002-01-01

    This report summarizes the key results obtained by the Vibration and Acoustics Laboratories at Virginia Tech over the period from January 1999 to December 2000 on the project 'Investigation of an Adaptive Herschel-Quincke Tube Concept for the Reduction of Tonal and Broadband Noise from Turbofan Engines', funded by NASA Langley Research Center. The Herschel-Quincke (HQ) tube concept is a developing technique the consists of circumferential arrays of tubes around the duct. The analytical model is developed to provide prediction and design guidelines for application of the HQ concept to turbofan engine inlets. An infinite duct model is developed and used to provide insight into attenuation mechanisms and design strategies. Based on this early model, the NASA-developed TBIEM3D code is modified for the HQ system. This model allows for investigation of the HQ system combined with a passive liner.

  17. The Aerodynamic Performance of an Over-the-Rotor Liner With Circumferential Grooves on a High Bypass Ratio Turbofan Rotor

    NASA Technical Reports Server (NTRS)

    Bozak, Richard F.; Hughes, Christopher E.; Buckley, James

    2013-01-01

    While liners have been utilized throughout turbofan ducts to attenuate fan noise, additional attenuation is obtainable by placing an acoustic liner over-the-rotor. Previous experiments have shown significant fan performance losses when acoustic liners are installed over-the-rotor. The fan blades induce an oscillating flow in the acoustic liners which results in a performance loss near the blade tip. An over-the-rotor liner was designed with circumferential grooves between the fan blade tips and the acoustic liner to reduce the oscillating flow in the acoustic liner. An experiment was conducted in the W-8 Single-Stage Axial Compressor Facility at NASA Glenn Research Center on a 1.5 pressure ratio fan to evaluate the impact of this over-the-rotor treatment design on fan aerodynamic performance. The addition of a circumferentially grooved over-the-rotor design between the fan blades and the acoustic liner reduced the performance loss, in terms of fan adiabatic efficiency, to less than 1 percent which is within the repeatability of this experiment.

  18. The Aerodynamic Performance of an Over-The-Rotor Liner with Circumferential Grooves on a High Bypass Ratio Turbofan Rotor

    NASA Technical Reports Server (NTRS)

    Bozak, Rick; Hughes, Christopher; Buckley, James

    2013-01-01

    While liners have been utilized throughout turbofan ducts to attenuate fan noise, additional attenuation is obtainable by placing an acoustic liner over-the-rotor. Previous experiments have shown significant fan performance losses when acoustic liners are installed over-the-rotor. The fan blades induce an oscillating flow in the acoustic liners which results in a performance loss near the blade tip. An over-the-rotor liner was designed with circumferential grooves between the fan blade tips and the acoustic liner to reduce the oscillating flow in the acoustic liner. An experiment was conducted in the W-8 Single-Stage Axial Compressor Facility at NASA Glenn Research Center on a 1.5 pressure ratio fan to evaluate the impact of this over-the-rotor treatment design on fan aerodynamic performance. The addition of a circumferentially grooved over-the-rotor design between the fan blades and the acoustic liner reduced the performance loss, in terms of fan adiabatic efficiency, to less than 1% which is within the repeatability of this experiment.

  19. Large Engine Technology (LET) Task XXXVII Low-Bypass Ratio Mixed Turbofan Engine Subsonic Jet Noise Reduction Program Test Report

    NASA Technical Reports Server (NTRS)

    Hauser, Joseph R.; Zysman, Steven H.; Barber, Thomas J.

    2001-01-01

    NASA Glenn Research Center supported a three year effort to develop the technology for reducing jet noise from low-bypass ratio engines. This effort concentrated on both analytical and experimental approaches using various mixer designs. CFD and MGB predictions are compared with LDV and noise data, respectively. While former predictions matched well with data, experiment shows a need for improving the latter predictions. Data also show that mixing noise can be sensitive to engine hardware upstream of the mixing exit plane.

  20. ADAM: An Axisymmetric Duct Aeroacoustic Modeling system. [aircraft turbofan engines

    NASA Technical Reports Server (NTRS)

    Abrahamson, A. L.

    1983-01-01

    An interconnected system of computer programs for analyzing the propagation and attenuation of sound in aeroengine ducts containing realistic compressible subsonic mean flows, ADAM was developed primarily for research directed towards the reduction of noise emitted from turbofan aircraft engines. The two basic components are a streamtube curvature program for determination of the mean flow, and a finite element code for solution of the acoustic propagation problem. The system, which has been specifically tailored for ease of use, is presently installed at NASA Langley Reseach Center on a Control Data Cyber 175 Computer under the NOS Operating system employing a Tektronix terminal for interactive graphics. The scope and organization of the ADAM system is described. A users guide, examples of input data, and results for selected cases are included.

  1. Luminescent Paints Used for Rotating Temperature and Pressure Measurements on Scale-Model High-Bypass-Ratio Fans

    NASA Technical Reports Server (NTRS)

    Bencic, Timothy J.

    1998-01-01

    NASA Lewis Research Center is a leader in the application of temperature- and pressuresensitive paints (TSP and PSP) in rotating environments. Tests were recently completed on several scale model, high-bypass-ratio turbofans in Lewis' 9- by 15-Foot Low-Speed Wind Tunnel. Two of the test objectives were to determine the aerodynamic and acoustic performance of the fan designs. Using TSP and PSP, researchers successfully achieved fullfield aerodynamic loading profiles. The visualized loading profiles may help researchers identify factors contributing to the fans' performance and to the acoustic characteristics associated with the flow physics on the surface of the blades.

  2. Rate-Based Model Predictive Control of Turbofan Engine Clearance

    NASA Technical Reports Server (NTRS)

    DeCastro, Jonathan A.

    2006-01-01

    An innovative model predictive control strategy is developed for control of nonlinear aircraft propulsion systems and sub-systems. At the heart of the controller is a rate-based linear parameter-varying model that propagates the state derivatives across the prediction horizon, extending prediction fidelity to transient regimes where conventional models begin to lose validity. The new control law is applied to a demanding active clearance control application, where the objectives are to tightly regulate blade tip clearances and also anticipate and avoid detrimental blade-shroud rub occurrences by optimally maintaining a predefined minimum clearance. Simulation results verify that the rate-based controller is capable of satisfying the objectives during realistic flight scenarios where both a conventional Jacobian-based model predictive control law and an unconstrained linear-quadratic optimal controller are incapable of doing so. The controller is evaluated using a variety of different actuators, illustrating the efficacy and versatility of the control approach. It is concluded that the new strategy has promise for this and other nonlinear aerospace applications that place high importance on the attainment of control objectives during transient regimes.

  3. Improved Finite Element Modeling of the Turbofan Engine Inlet Radiation Problem

    NASA Technical Reports Server (NTRS)

    Roy, Indranil Danda; Eversman, Walter; Meyer, H. D.

    1993-01-01

    Improvements have been made in the finite element model of the acoustic radiated field from a turbofan engine inlet in the presence of a mean flow. The problem of acoustic radiation from a turbofan engine inlet is difficult to model numerically because of the large domain and high frequencies involved. A numerical model with conventional finite elements in the near field and wave envelope elements in the far field has been constructed. By employing an irrotational mean flow assumption, both the mean flow and the acoustic perturbation problem have been posed in an axisymmetric formulation in terms of the velocity potential; thereby minimizing computer storage and time requirements. The finite element mesh has been altered in search of an improved solution. The mean flow problem has been reformulated with new boundary conditions to make it theoretically rigorous. The sound source at the fan face has been modeled as a combination of positive and negative propagating duct eigenfunctions. Therefore, a finite element duct eigenvalue problem has been solved on the fan face and the resulting modal matrix has been used to implement a source boundary condition on the fan face in the acoustic radiation problem. In the post processing of the solution, the acoustic pressure has been evaluated at Gauss points inside the elements and the nodal pressure values have been interpolated from them. This has significantly improved the results. The effect of the geometric position of the transition circle between conventional finite elements and wave envelope elements has been studied and it has been found that the transition can be made nearer to the inlet than previously assumed.

  4. Aircraft turbofans: new economic and environmental benefits

    SciTech Connect

    Sampl, F.R.; Shank, M.E.

    1985-09-01

    This article describes turbofan and turboprop engines. Advanced turbofans and turboprop engines, by continuing to reduce the velocities of the jet exhaust and fan tip speed, can provide significant noise reductions. New combustors incorporated into these engines have reduced smoke, hydrocarbons and carbon monoxide to levels below the current requirements. The third generation of turbofans will continue to increase fuel efficiency and reduce aircraft operating costs. They are more modular in design and consist of half as many parts as the earlier engines, reducing maintenance time by half. Some of the key features of the new turbofan concept include: a very high bypass ratio/compression ratio cycle; swept fan blades; a thin, low-loss nacelle; low-loss reduction gearing; new materials; advanced compressor/turbine airfoils; and high-speed rotors with improved clearance control.

  5. Noise Benefits of Rotor Trailing Edge Blowing for a Model Turbofan

    NASA Technical Reports Server (NTRS)

    Woodward, Richard P.; Fite, E. Brian; Podboy, Gary G.

    2007-01-01

    An advanced model turbofan was tested in the NASA Glenn 9- by 15-Foot Low Speed Wind Tunnel (9x15 LSWT) to explore far field acoustic effects associated with rotor Trailing-Edge-Blowing (TEB) for a modern, 1.294 stage pressure ratio turbofan model. The TEB rotor (Fan9) was designed to be aerodynamically similar to the previously tested Fan1, and used the same stator and nacelle hardware. Fan9 was designed with trailing edge blowing slots using an external air supply directed through the rotor hub. The TEB flow was heated to approximate the average fan exit temperature at each fan test speed. Rotor root blockage inserts were used to block TEB to all but the outer 40 and 20% span in addition to full-span blowing. A configuration with full-span TEB on alternate rotor blades was also tested. Far field acoustic data were taken at takeoff/approach conditions at 0.10 tunnel Mach. Far-field acoustic results showed that full-span blowing near 2.0% of the total flow could reduce the overall sound power level by about 2 dB. This noise reduction was observed in both the rotor-stator interaction tones and for the spectral broadband noise levels. Blowing only the outer span region was not very effective for lowering noise, and actually increased the far field noise level in some instances. Full-span blowing of alternate blades at 1.0% of the overall flow rate (equivalent to full-span blowing of all blades at 2.0% flow) showed a more modest noise decrease relative to full-span blowing of all blades. Detailed hot film measurements of the TEB rotor wake at 2.0% flow showed that TEB was not every effective for filling in the wake defect at approach fan speed toward the tip region, but did result in overfilling the wake toward the hub. Downstream turbulence measurements supported this finding, and support the observed reduction in spectral broadband noise.

  6. Comprehensive Report of Fan Performance From Duct Rake Instrumentation on 1.294 Pressure Ratio, 806 ft/sec Tip Speed Turbofan Simulator Models

    NASA Technical Reports Server (NTRS)

    Jeracki, Robert J.

    2006-01-01

    A large scale model representative of an advanced ducted propulsor-type, low-noise, very high bypass ratio turbofan engine was tested for acoustics, aerodynamic performance, and off-design operability in the NASA Glenn 9- by 15-Foot Low-Speed Wind Tunnel. The test was part of NASA s Advanced Subsonic Technology Noise Reduction Program. The low tip speed fan, nacelle, and un-powered core passage were simulated. As might be expected, the effect of stall management casing treatment was a performance penalty. Reducing the recirculating flow at the fan tip reduced the penalty while still providing sufficient stall margin. Two fans were tested with the same aerodynamic design; one with graphite composite material, and the other with solid titanium. There were surprising performance differences between the two fans, though both blades showed some indication of transitional flow near the tips. Though the pressure and temperature ratios were low for this fan design, the techniques used to improve thermocouple measurement accuracy gave repeatable data with adiabatic efficiencies agreeing within 1 percent. The measured fan adiabatic efficiency at simulated takeoff conditions was 93.7 percent and matched the design intent.

  7. Turbofan forced mixer lobe flow modeling. 1: Experimental and analytical assessment

    NASA Technical Reports Server (NTRS)

    Barber, T.; Paterson, R. W.; Skebe, S. A.

    1988-01-01

    A joint analytical and experimental investigation of three-dimensional flowfield development within the lobe region of turbofan forced mixer nozzles is described. The objective was to develop a method for predicting the lobe exit flowfield. In the analytical approach, a linearized inviscid aerodynamical theory was used for representing the axial and secondary flows within the three-dimensional convoluted mixer lobes and three-dimensional boundary layer analysis was applied thereafter to account for viscous effects. The experimental phase of the program employed three planar mixer lobe models having different waveform shapes and lobe heights for which detailed measurements were made of the three-dimensional velocity field and total pressure field at the lobe exit plane. Velocity data was obtained using Laser Doppler Velocimetry (LDV) and total pressure probing and hot wire anemometry were employed to define exit plane total pressure and boundary layer development. Comparison of data and analysis was performed to assess analytical model prediction accuracy. As a result of this study a planar mixed geometry analysis was developed. A principal conclusion is that the global mixer lobe flowfield is inviscid and can be predicted from an inviscid analysis and Kutta condition.

  8. Development in Geared Turbofan Aeroengine

    NASA Astrophysics Data System (ADS)

    Mohd Tobi, A. L.; Ismail, A. E.

    2016-05-01

    This paper looks into the implementation of epicyclic gear system to the aeroengine in order to increase the efficiency of the engine. The improvement made is in the direction of improving fuel consumption, reduction in pollutant gasses and perceived noise. Introduction of epicyclic gear system is capable to achieve bypass ratio of up to 15:1 with the benefits of weight and noise reduction. Radical new aircraft designs and engine installation are being studied to overcome some of the challenges associated with the future geared turbofan and open-rotor engine.

  9. A Real-Time Simulator of a Turbofan Engine

    DTIC Science & Technology

    1989-03-01

    44j~ - i ~4 10 I’ Q Wk r7S~f~fNt4 0K - 4’ lt 4 .At .t’ 4--Q to Aa l A REAL-TIME SIMULATOR OF A TURBOFAN ENGINE Jonathan S. Litt n For Propulsion...error. "as" ,,,rmisu Mnim*& The F100 engine is a high performance, twin-spool, low by-pass ratio, turbofan engine . Figure 2 shows the locations of the...FORTRAN sim- ulation of a generalized turbofan engine . To create the simulator, the original HYTESS code was revised to incorporate F1O0 specific

  10. Application of frequency-domain linearized Euler solutions to the prediction of aft fan tones and comparison with experimental measurements on model scale turbofan exhaust nozzles

    NASA Astrophysics Data System (ADS)

    Özyörük, Y.; Tester, B. J.

    2011-08-01

    Although it is widely accepted that aircraft noise needs to be further reduced, there is an equally important, on-going requirement to accurately predict the strengths of all the different aircraft noise sources, not only to ensure that a new aircraft is certifiable and can meet the ever more stringent local airport noise rules but also to prioritize and apply appropriate noise source reduction technologies at the design stage. As the bypass ratio of aircraft engines is increased - in order to reduce fuel consumption, emissions and jet mixing noise - the fan noise that radiates from the bypass exhaust nozzle is becoming one of the loudest engine sources, despite the large areas of acoustically absorptive treatment in the bypass duct. This paper addresses this 'aft fan' noise source, in particular the prediction of the propagation of fan noise through the bypass exhaust nozzle/jet exhaust flow and radiation out to the far-field observer. The proposed prediction method is equally applicable to fan tone and fan broadband noise (and also turbine and core noise) but here the method is validated with measured test data using simulated fan tones. The measured data had been previously acquired on two model scale turbofan engine exhausts with bypass and heated core flows typical of those found in a modern high bypass engine, but under static conditions (i.e. no flight simulation). The prediction method is based on frequency-domain solutions of the linearized Euler equations in conjunction with perfectly matched layer equations at the inlet and far-field boundaries using high-order finite differences. The discrete system of equations is inverted by the parallel sparse solver MUMPS. Far-field predictions are carried out by integrating Kirchhoff's formula in frequency domain. In addition to the acoustic modes excited and radiated, some non-acoustic waves within the cold stream-ambient shear layer are also captured by the computations at some flow and excitation frequencies. By

  11. Potential improvements in turbofan engine fuel economy

    NASA Technical Reports Server (NTRS)

    Hines, R. W.; Gaffin, W. O.

    1976-01-01

    The method developed for initial evaluation of possible performance improvements in the NASA Aircraft Energy Efficiency Program, directed toward improving the fuel economy of turbofan engines, is outlined, and results of the evaluation of 100 candidate engine modifications are presented. The study indicates that fuel consumption improvements of as much as 5% may be possible in current JT3D, JT8D, and JT9D turbofan engines. Aerodynamic, thermodynamic, material, and structural advances are expected to yield fuel consumption improvements on the order of 10 to 15% in advanced turbofan engines, with the greatest improvement stemming from significantly higher cycle pressure ratios. Higher turbine temperature and fan bypass ratios are also expected to contribute to fuel conservation.

  12. 76 FR 64293 - Airworthiness Directives; CFM International, S. A. Model CFM56-5B Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-18

    ...) This AD applies to CFM International, S.A. CFM56-5B1/3, CFM56-5B2/3, CFM56-5B3/3, CFM56-5B4/3, CFM56-5B5/3, CFM56-5B6/3, CFM56-5B7/3, CFM56-5B8/3, CFM56-5B9/3, CFM56-5B3/3B1, and CFM56-5B4/ 3B1 engines..., S. A. Model CFM56-5B Series Turbofan......

  13. Modelling of natural and bypass transition in aerodynamics

    NASA Astrophysics Data System (ADS)

    Fürst, Jiří; Straka, Petr; Příhoda, Jaromír

    2014-03-01

    Most of transition models are proposed for modelling of the bypass transition common in the internal aerodynamics especially in turbomachinery where free stream turbulence is the dominant parameter affecting the transition onset. Free-stream turbulence level in the external aerodynamics is usually noticeably lower and so the natural transition often occurs in flows around airfoils. The transition model with the algebraic equation for the intermittency coefficient proposed originally by Straka and Příhoda [3] for the bypass transition was modified for modelling of the transition at low free-stream turbulence. The modification is carried out using experimental data of Schubauer and Skramstad [18]. Further, the three-equation k-kL-ω model proposed by Walters and Cokljat [10] was used for the modelling of the transition at low free-stream turbulence. Both models were tested by means of the incompressible flow around airfoils at moderate and very low free-stream turbulence.

  14. TF-34 turbofan quiet engine study

    NASA Technical Reports Server (NTRS)

    Edkins, D. P.; Hirschkron, R.; Lee, R.

    1972-01-01

    A study of high bypass turbofan engines in heavily sound-suppressed nacelles based on the TF-34 engine. The four-engine noise objective was 95 PNdb at four locations typical of takeoff and landing. Three engines were studied; these had fan pressure ratios, bypass ratios, and fan tip speeds respectively of 1.48/6.5/404 m/sec (1327 ft/sec), 1.25/13/305 (1000), 1.25/13/366(1200). The bypass 13 engines had a variable pitch fan, direct- and gear-driven. Noise suppressive treatment was identified which met 95 PNdb objective except for sideline liftoff at 6.5 bypass, full power, which was 2 PNdb noisier; at 90% power, 95 PNdb was achieved.

  15. Parameterization of a Conventional and Regenerated UHB Turbofan

    NASA Astrophysics Data System (ADS)

    Oliveira, Fábio; Brójo, Francisco

    2015-09-01

    The attempt to improve aircraft engines efficiency resulted in the evolution from turbojets to the first generation low bypass ratio turbofans. Today, high bypass ratio turbofans are the most traditional type of engine in commercial aviation. Following many years of technological developments and improvements, this type of engine has proved to be the most reliable facing the commercial aviation requirements. In search of more efficiency, the engine manufacturers tend to increase the bypass ratio leading to ultra-high bypass ratio (UHB) engines. Increased bypass ratio has clear benefits in terms of propulsion system like reducing the specific fuel consumption. This study is aimed at a parametric analysis of a UHB turbofan engine focused on short haul flights. Two cycle configurations (conventional and regenerated) were studied, and estimated values of their specific fuel consumption (TSFC) and specific thrust (Fs) were determined. Results demonstrate that the regenerated cycle may contribute towards a more economic and friendly aero engines in a higher range of bypass ratio.

  16. 77 FR 57007 - Airworthiness Directives; Pratt & Whitney Division Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-17

    ... Division Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY..., PW4152, PW4156A, PW4158, PW4164, PW4168, PW4168A, PW4460, and PW4462 turbofan engines. That AD currently... rotor disk assembly for certain affected engine models. We are issuing this AD to prevent failure of...

  17. 78 FR 16620 - Airworthiness Directives; Pratt & Whitney Division Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-18

    ... Division Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed... Division (PW) turbofan engine models PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 with a... air seal, which could lead to an uncontained engine failure and damage to the airplane. DATES: We...

  18. 77 FR 40822 - Airworthiness Directives; Pratt & Whitney Division Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-11

    ... Division Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed..., PW4160, PW4460, PW4462, and PW4650 turbofan engines, including models with any dash number suffix. This... could lead to LPT rotor damage, uncontained engine failure, and damage to the airplane. DATES: We...

  19. Turbofan Volume Dynamics Model for Investigations of Aero-Propulso-Servo-Elastic Effects in a Supersonic Commercial Transport

    NASA Technical Reports Server (NTRS)

    Connolly, Joseph W.; Kopasakis, George; Lemon, Kimberly A.

    2010-01-01

    A turbofan simulation has been developed for use in aero-propulso-servo-elastic coupling studies, on supersonic vehicles. A one-dimensional lumped volume approach is used whereby each component (fan, high-pressure compressor, combustor, etc.) is represented as a single volume using characteristic performance maps and conservation equations for continuity, momentum and energy. The simulation is developed in the MATLAB/SIMULINK (The MathWorks, Inc.) environment in order to facilitate controls development, and ease of integration with a future aero-servo-elastic vehicle model being developed at NASA Langley. The complete simulation demonstrated steady state results that closely match a proposed engine suitable for a supersonic business jet at the cruise condition. Preliminary investigation of the transient simulation revealed expected trends for fuel flow disturbances as well as upstream pressure disturbances. A framework for system identification enables development of linear models for controller design. Utilizing this framework, a transfer function modeling an upstream pressure disturbance s impacts on the engine speed is developed as an illustrative case of the system identification. This work will eventually enable an overall vehicle aero-propulso-servo-elastic model

  20. Turbofan forced mixer lobe flow modeling. 2: Three-dimensional inviscid mixer analysis (FLOMIX)

    NASA Technical Reports Server (NTRS)

    Barber, T.

    1988-01-01

    A three-dimensional potential analysis (FLOMIX) was formulated and applied to the inviscid flow over a turbofan foced mixer. The method uses a small disturbance formulation to analytically uncouple the circumferential flow from the radial and axial flow problem, thereby reducing the analysis to the solution of a series of axisymmetric problems. These equations are discretized using a flux volume formulation along a Cartesian grid. The method extends earlier applications of the Cartesian method to complex cambered geometries. The effects of power addition are also included within the potential formulation. Good agreement is obtained with an alternate small disturbance analysis for a high penetration symmetric mixer in a planar duct. In addition, calculations showing pressure distributions and induced secondary vorticity fields are presented for practical trubofan mixer configurations, and where possible, comparison was made with available experimental data. A detailed description of the required data input and coordinate definition is presented along with a sample data set for a practical forced mixer configuration. A brief description of the program structure and subroutines is also provided.

  1. Reduced-Order Modeling and Wavelet Analysis of Turbofan Engine Structural Response Due to Foreign Object Damage "FOD" Events

    NASA Technical Reports Server (NTRS)

    Turso, James A.; Lawrence, Charles; Litt, Jonathan S.

    2007-01-01

    The development of a wavelet-based feature extraction technique specifically targeting FOD-event induced vibration signal changes in gas turbine engines is described. The technique performs wavelet analysis of accelerometer signals from specified locations on the engine and is shown to be robust in the presence of significant process and sensor noise. It is envisioned that the technique will be combined with Kalman filter thermal/ health parameter estimation for FOD-event detection via information fusion from these (and perhaps other) sources. Due to the lack of high-frequency FOD-event test data in the open literature, a reduced-order turbofan structural model (ROM) was synthesized from a finite-element model modal analysis to support the investigation. In addition to providing test data for algorithm development, the ROM is used to determine the optimal sensor location for FOD-event detection. In the presence of significant noise, precise location of the FOD event in time was obtained using the developed wavelet-based feature.

  2. Reduced-Order Modeling and Wavelet Analysis of Turbofan Engine Structural Response Due to Foreign Object Damage (FOD) Events

    NASA Technical Reports Server (NTRS)

    Turso, James; Lawrence, Charles; Litt, Jonathan

    2004-01-01

    The development of a wavelet-based feature extraction technique specifically targeting FOD-event induced vibration signal changes in gas turbine engines is described. The technique performs wavelet analysis of accelerometer signals from specified locations on the engine and is shown to be robust in the presence of significant process and sensor noise. It is envisioned that the technique will be combined with Kalman filter thermal/health parameter estimation for FOD-event detection via information fusion from these (and perhaps other) sources. Due to the lack of high-frequency FOD-event test data in the open literature, a reduced-order turbofan structural model (ROM) was synthesized from a finite element model modal analysis to support the investigation. In addition to providing test data for algorithm development, the ROM is used to determine the optimal sensor location for FOD-event detection. In the presence of significant noise, precise location of the FOD event in time was obtained using the developed wavelet-based feature.

  3. Experimental Program for the Evaluation of Turbofan/Turboshaft Conversion Technology

    DTIC Science & Technology

    1982-01-01

    Wenzel National Aeronautics and Space Administration Lewis Research Center Cleveland, Ohio 44135 SUMMARY -A TF34 turbofan engine is being modified to...of a Part-Span Variable Inlet Guide Vane on the Performance of a High-Bypass Turbofan Engine . NASA TM 82617, 1981. 5. Nieberding, W. C.; and Pollack...produce shaft power from an output coupling on the fan disk when variable inlet guide vanes are closed to reduce fan airflow. The engine , called a

  4. JT8D-100 turbofan engine, phase 1. [noise reduction

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The JT8D turbofan engine, widely used in short and medium range transport aircraft, contributes substantially to airport community noise. The jet noise is predominant in the JT8D engine and may be reduced in a modified engine, without loss of thrust, by increasing the airflow to reduce jet velocity. A configuration study evaluated the effects of fan airflow, fan pressure ratio, and bypass ratio on noise, thrust, and fuel comsumption. The cycle selected for the modified engine was based upon an increased diameter, single-stage fan and two additional core engine compressor stages, which replace the existing two-stage fan. Modifications were also made to the low pressure turbine to provide the increased torque required by the larger diameter fan. The resultant JT8D-100 engine models have the following characteristics at take-off thrust, compared to the current JT8D engine: Airflow and bypass ratio are increased, and fan pressure ratio and engine speed are reduced. The resultant engine is also longer, larger in diameter, and heavier than the JT8D base model, but these latter changes are compensated by the increased thrust and decreased fuel comsumption of the modified engine, thus providing the capability for maintaining the performance of the current JT8D-powered aircraft.

  5. Modeling of Highly Instrumented Honeywell Turbofan Engine Tested with Ice Crystal Ingestion in the NASA Propulsion System Laboratory

    NASA Technical Reports Server (NTRS)

    Veres, Joseph P.; Jorgenson, Philip C. E.; Jones, Scott M.

    2016-01-01

    The Propulsion Systems Laboratory (PSL), an altitude test facility at NASA Glenn Research Center, has been used to test a highly instrumented turbine engine at simulated altitude operating conditions. This is a continuation of the PSL testing that successfully duplicated the icing events that were experienced in a previous engine (serial LF01) during flight through ice crystal clouds, which was the first turbofan engine tested in PSL. This second model of the ALF502R-5A serial number LF11 is a highly instrumented version of the previous engine. The PSL facility provides a continuous cloud of ice crystals with controlled characteristics of size and concentration, which are ingested by the engine during operation at simulated altitudes. Several of the previous operating points tested in the LF01 engine were duplicated to confirm repeatability in LF11. The instrumentation included video cameras to visually illustrate the accretion of ice in the low pressure compressor (LPC) exit guide vane region in order to confirm the ice accretion, which was suspected during the testing of the LF01. Traditional instrumentation included static pressure taps in the low pressure compressor inner and outer flow path walls, as well as total pressure and temperature rakes in the low pressure compressor region. The test data was utilized to determine the losses and blockages due to accretion in the exit guide vane region of the LPC. Multiple data points were analyzed with the Honeywell Customer Deck. A full engine roll back point was modeled with the Numerical Propulsion System Simulation (NPSS) code. The mean line compressor flow analysis code with ice crystal modeling was utilized to estimate the parameters that indicate the risk of accretion, as well as to estimate the degree of blockage and losses caused by accretion during a full engine roll back point. The analysis provided additional validation of the icing risk parameters within the LPC, as well as the creation of models for

  6. Bypass Transitional Flow Calculations Using a Navier-Stokes Solver and Two-Equation Models

    NASA Technical Reports Server (NTRS)

    Liuo, William W.; Shih, Tsan-Hsing; Povinelli, L. A. (Technical Monitor)

    2000-01-01

    Bypass transitional flows over a flat plate were simulated using a Navier-Stokes solver and two equation models. A new model for the bypass transition, which occurs in cases with high free stream turbulence intensity (TI), is described. The new transition model is developed by including an intermittency correction function to an existing two-equation turbulence model. The advantages of using Navier-Stokes equations, as opposed to boundary-layer equations, in bypass transition simulations are also illustrated. The results for two test flows over a flat plate with different levels of free stream turbulence intensity are reported. Comparisons with the experimental measurements show that the new model can capture very well both the onset and the length of bypass transition.

  7. Towards an Automated Full-Turbofan Engine Numerical Simulation

    NASA Technical Reports Server (NTRS)

    Reed, John A.; Turner, Mark G.; Norris, Andrew; Veres, Joseph P.

    2003-01-01

    The objective of this study was to demonstrate the high-fidelity numerical simulation of a modern high-bypass turbofan engine. The simulation utilizes the Numerical Propulsion System Simulation (NPSS) thermodynamic cycle modeling system coupled to a high-fidelity full-engine model represented by a set of coupled three-dimensional computational fluid dynamic (CFD) component models. Boundary conditions from the balanced, steady-state cycle model are used to define component boundary conditions in the full-engine model. Operating characteristics of the three-dimensional component models are integrated into the cycle model via partial performance maps generated automatically from the CFD flow solutions using one-dimensional meanline turbomachinery programs. This paper reports on the progress made towards the full-engine simulation of the GE90-94B engine, highlighting the generation of the high-pressure compressor partial performance map. The ongoing work will provide a system to evaluate the steady and unsteady aerodynamic and mechanical interactions between engine components at design and off-design operating conditions.

  8. Analysis of Turbofan Design Options for an Advanced Single-Aisle Transport Aircraft

    NASA Technical Reports Server (NTRS)

    Guynn, Mark D.; Berton, Jeffrey J.; Fisher, Kenneth L.; Haller, William J.; Tong, Michael T.; Thurman, Douglas R.

    2009-01-01

    The desire for higher engine efficiency has resulted in the evolution of aircraft gas turbine engines from turbojets, to low bypass ratio, first generation turbofans, to today's high bypass ratio turbofans. It is possible that future designs will continue this trend, leading to very-high or ultra-high bypass ratio (UHB) engines. Although increased bypass ratio has clear benefits in terms of propulsion system metrics such as specific fuel consumption, these benefits may not translate into aircraft system level benefits due to integration penalties. In this study, the design trade space for advanced turbofan engines applied to a single-aisle transport (737/A320 class aircraft) is explored. The benefits of increased bypass ratio and associated enabling technologies such as geared fan drive are found to depend on the primary metrics of interest. For example, bypass ratios at which fuel consumption is minimized may not require geared fan technology. However, geared fan drive does enable higher bypass ratio designs which result in lower noise. Regardless of the engine architecture chosen, the results of this study indicate the potential for the advanced aircraft to realize substantial improvements in fuel efficiency, emissions, and noise compared to the current vehicles in this size class.

  9. Experimental investigations of the steady flow through an idealized model of a femoral artery bypass

    NASA Astrophysics Data System (ADS)

    Giurgea, Corina; Bode, Florin; Ioan Budiu, Octavian; Nascutiu, Lucian; Banyai, Daniel; Damian, Mihai

    2014-03-01

    The present paper presents the steps taken by the authors in the first stage of an experimental program within a larger national research project whose objective is to characterize the flow through a femoral artery bypass with a view to finding solutions for its optimization. The objective of the stage is to investigate by means of the PIV method the stationary flow through a bypass model with an idealized geometry. A bypass assembly which reunites the idealized geometry models of the proximal and distal anastomoses, and which respects the lengths of a femoral artery bypass was constructed on the basis of data for a real patient provided by medical investigations. With the aim of testing the model and the established experimental set-up with regard to their suitability for the assessment of the velocity field associated to the steady flow through the bypass, three zones that can restore the whole distal anastomosis were PIV investigated. The measurements were taken in the conditions of maintained inflow at the bypass entry of 0.9 l / min (Re = 600). The article presents comparatively the flow spectra and the velocity fields for each zone obtained in two situations: with the femoral artery completely occluded and completely open.

  10. Airesearch QCGAT program. [quiet clean general aviation turbofan engines

    NASA Technical Reports Server (NTRS)

    Heldenbrand, R. W.; Norgren, W. M.

    1979-01-01

    A model TFE731-1 engine was used as a baseline for the NASA quiet clean general aviation turbofan engine and engine/nacelle program designed to demonstrate the applicability of large turbofan engine technology to small general aviation turbofan engines, and to obtain significant reductions in noise and pollutant emissions while reducing or maintaining fuel consumption levels. All new technology design for rotating parts and all items in the engine and nacelle that contributed to the acoustic and pollution characteristics of the engine system were of flight design, weight, and construction. The major noise, emissions, and performance goals were met. Noise levels estimated for the three FAR Part 36 conditions, are 10 t0 15 ENPdB below FAA requirements; emission values are considerably reduced below that of current technology engines; and the engine performance represents a TSFC improvement of approximately 9 percent over other turbofan engines.

  11. Aircraft turbofan noise

    NASA Technical Reports Server (NTRS)

    Groeneweg, J. F.; Rice, E. J.

    1983-01-01

    Turbofan noise generation and suppression in aircraft engines are reviewed. The chain of physical processes which connect unsteady flow interactions with fan blades to far field noise is addressed. Mechanism identification and description, duct propagation, radiation and acoustic suppression are discussed. The experimental technique of fan inflow static tests are discussed. Rotor blade surface pressure and wake velocity measurements aid in the determination of the types and strengths of the generation mechanisms. Approaches to predicting or measuring acoustic mode content, optimizing treatment impedance to maximize attenuation, translating impedance into porous wall structure and interpreting far field directivity patterns are illustrated by comparisons of analytical and experimental results. The interdependence of source and acoustic treatment design to minimize far field noise is emphasized. Area requiring further research are discussed and the relevance of aircraft turbofan results to quieting other turbomachinery installations is addressed.

  12. 77 FR 69569 - Special Conditions: Embraer S.A., Model EMB-550 Airplanes; Flight Envelope Protection: Pitch and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-20

    ... Model EMB-550 airplane. The Model EMB-550 airplane is the first of a new family of jet airplanes... 12 passengers. It is equipped with two Honeywell HTF7500-E medium bypass ratio turbofan engines mounted on aft fuselage pylons. Each engine produces approximately 6,540 pounds of thrust for...

  13. Combined pressure and temperature distortion effects on internal flow of a turbofan engine

    NASA Technical Reports Server (NTRS)

    Braithwaite, W. M.; Soeder, R. H.

    1979-01-01

    An additional data base for improving and verifying a computer simulation developed by an engine manufacturer was obtained. The multisegment parallel compressor simulation was designed to predict the effects of steady-state circumferential inlet total-pressure and total-temperature distortions on the flows into and through a turbofan compression system. It also predicts the degree of distortion that will result in surge of the compressor. The effect of combined 180 deg square-wave distortion patterns of total pressure and total temperature in various relative positions is reported. The observed effects of the combined distortion on a unitary bypass ratio turbofan engine are presented in terms of total and static pressure profiles and total temperature profiles at stations ahead of the inlet guide vanes as well as through the fan-compressor system. These observed profiles are compared with those predicted by the complex multisegment model. The effects of relative position of the two components comprising the combined distortion on the degree resulting in surge are discussed. Certain relative positions required less combined distortion than either a temperature or pressure distortion by itself.

  14. Noise levels from a model turbofan engine with simulated noise control measures applied

    NASA Technical Reports Server (NTRS)

    Hall, David G.; Woodward, Richard P.

    1993-01-01

    A study of estimated full-scale noise levels based on measured levels from the Advanced Ducted Propeller (ADP) sub-scale model is presented. Testing of this model was performed in the NASA Lewis Low Speed Anechoic Wind Tunnel at a simulated takeoff condition of Mach 0.2. Effective Perceived Noise Level (EPNL) estimates for the baseline configuration are documented, and also used as the control case in a study of the potential benefits of two categories of noise control. The effect of active noise control is evaluated by artificially removing various rotor-stator interaction tones. Passive noise control is simulated by applying a notch filter to the wind tunnel data. Cases with both techniques are included to evaluate hybrid active-passive noise control. The results for EPNL values are approximate because the original source data was limited in bandwidth and in sideline angular coverage. The main emphasis is on comparisons between the baseline and configurations with simulated noise control measures.

  15. A Mode Detection Method Using the Azimuthal Directivity of a Turbofan Model

    NASA Technical Reports Server (NTRS)

    Thomas, R. H.; Farassat, F.; Clark, L. R.; Gerhold, C. H.; Kelly, J. J.; Becker, L. E.

    1999-01-01

    The azimuthal, far field directivity of a scale fan model was measured in high resolution. The model is a 12 inch diameter rotor with 16 blades followed by 40 stator vanes. The tests were conducted at the nominal 100% speed corresponding to a tip speed of 905 ft/sec. Measurement of the radiated sound field, forward of the fan, was made in an anechoic chamber with an inflow control device and a baffle separating the aft and forward radiated interaction noise. The acoustic field was surveyed with a circular hoop array of 16 microphones which was moved to 14 axial stations. At each axial station the hoop was rotated in half-degree increments to take 736 points in the azimuthal angle. In addition to sound pressure level, the phase angle relative to a reference microphone was measured at each point. The sound pressure level is shown to vary in patterns by 10-15 dB especially for the fundamental tone but also for the first and second harmonic. A far field mode detection method has been developed and used with the data which determines the modes generated by the fan and which then interact to form the azimuthal directivity.

  16. Acoustic Mode Measurements in the Inlet of a Model Turbofan Using a Continuously Rotating Rake

    NASA Technical Reports Server (NTRS)

    Heidelberg, Laurence J.; Hall, David G.

    1992-01-01

    Comprehensive measurements of the spinning acoustic mode structure in the inlet of the Advanced Ducted Propeller (ADP) have been completed. These measurements were taken using a unique and previously untried method which was first proposed by T.G. Sofrin. A continuously rotating microphone system was employed. The ADP model was designed and built by Pratt & Whitney and tested in the NASA Lewis 9- by 15-foot Anechoic Wind Tunnel. Three inlet configurations were tested with cut-on and cutoff stator vane sets. The cutoff stator was designed to suppress all modes at the blade passing frequency. Rotating rake measurements indicate that several extraneous circumferential modes were active. The mode orders suggest that their source was an interaction between the rotor and small interruptions in the casing tip treatment. The cut-on stator produced the expected circumferential modes plus higher levels of the unexpected modes seen with the cutoff stator.

  17. Acoustic mode measurements in the inlet of a model turbofan using a continuously rotating rake

    NASA Astrophysics Data System (ADS)

    Heidelberg, Laurence J.; Hall, David G.

    1993-01-01

    Comprehensive measurements of the spinning acoustic mode structure in the inlet of the Advanced Ducted Propeller (ADP) have been completed. These measurements were taken using a unique and previously untried method which was first proposed by T.G. Sofrin. A continuously rotating microphone system was employed. The ADP model was designed and built by Pratt & Whitney and tested in the NASA Lewis 9- by 15-foot Anechoic Wind Tunnel. Three inlet configurations were tested with cut-on and cutoff stator vane sets. The cutoff stator was designed to suppress all modes at the blade passing frequency. Rotating rake measurements indicate that several extraneous circumferential modes were active. The mode orders suggest that their source was an interaction between the rotor and small interruptions in the casing tip treatment. The cut-on stator produced the expected circumferential modes plus higher levels of the unexpected modes seen with the cutoff stator.

  18. Experimental study of noise sources and acoustic propagation in a turbofan model

    NASA Astrophysics Data System (ADS)

    Lewy, S.; Canard-Caruana, S.; Julliard, J.

    1990-10-01

    Experimental studies of the acoustic radiation of subsonic fans mainly due to blade and vane presure fluctuations were performed in the SNECMA 5C2 compressor anechoic facility. A brief description of the test rig is presented noting that the CA5 turbojet engine model fan has a diameter of 47 cm, 48 blades, and a nominal rotation speed of 12,600 rpm. The two chief experiments discussed are the measurement of blade and vane pressure fluctuations by thin-film transducers and the spinning mode analysis of the sound field propagating in the intake duct. Several examples of applications are discussed, and it is shown that an inflow control device, as expected, reduces the aerodynamic disturbances by about 10 dB. Rotor-stator interaction tones are determined by the modal analysis, and it is found that a duct lining with a length of one duct radius could give an insertion loss up to 20 dB in flight.

  19. Ribosome bypassing at serine codons as a test of the model of selective transfer RNA charging

    PubMed Central

    Lindsley, Dale; Bonthuis, Paul; Gallant, Jonathan; Tofoleanu, Teodora; Elf, Johan; Ehrenberg, Måns

    2005-01-01

    Recently, a model of the flux of amino acids through transfer RNAs (tRNAs) and into protein has been developed. The model predicts that the charging level of different isoacceptors carrying the same amino acid respond very differently to variation in supply of the amino acid or of the rate of charging. It has also been shown that ribosome bypassing is specifically stimulated at ‘hungry' codons calling for an aminoacyl-tRNA in short supply. We have constructed two reporters of bypassing, which differ only in the identity of the serine codon subjected to starvation. The stimulation of bypassing as a function of starvation differed greatly between the two serine codons, in good agreement with the quantitative predictions of the model. PMID:15678161

  20. Online Normalization Algorithm for Engine Turbofan Monitoring

    DTIC Science & Technology

    2014-10-02

    it auto-adapts itself with piecewise linear models. 1. INTRODUCTION Turbofan engine abnormality diagnosis uses three steps: reduction of...applications. At component level we monitor the start system (Flandrois, Lacaille, Massé, & Ausloos, 2009; Lacaille, 2009), the fuel system and other...Control RACC Rotor Active Clearance Control ECS Environmental Control System TLA Thrust Lever Angle N1 Fan Speed XM Mach Number Endogenous

  1. Analysis of an advanced technology subsonic turbofan incorporating revolutionary materials

    NASA Technical Reports Server (NTRS)

    Knip, Gerald, Jr.

    1987-01-01

    Successful implementation of revolutionary composite materials in an advanced turbofan offers the possibility of further improvements in engine performance and thrust-to-weight ratio relative to current metallic materials. The present analysis determines the approximate engine cycle and configuration for an early 21st century subsonic turbofan incorporating all composite materials. The advanced engine is evaluated relative to a current technology baseline engine in terms of its potential fuel savings for an intercontinental quadjet having a design range of 5500 nmi and a payload of 500 passengers. The resultant near optimum, uncooled, two-spool, advanced engine has an overall pressure ratio of 87, a bypass ratio of 18, a geared fan, and a turbine rotor inlet temperature of 3085 R. Improvements result in a 33-percent fuel saving for the specified misssion. Various advanced composite materials are used throughout the engine. For example, advanced polymer composite materials are used for the fan and the low pressure compressor (LPC).

  2. Particles deposition induced by the magnetic field in the coronary bypass graft model

    NASA Astrophysics Data System (ADS)

    Bernad, Sandor I.; Totorean, Alin F.; Vekas, Ladislau

    2016-03-01

    Bypass graft failures is a complex process starting with intimal hyperplasia development which involve many hemodynamic and biological factors. This work presents experimental results regarding the possibility to use magnetic drug delivery to prevent the development of the intimal hyperplasia using a simplified but intuitive model. The primary goal is to understand the magnetic particle deposition in the anastomosis region of the bypass graft taking into account the complex flow field created in this area which involves recirculation region, flow mixing and presence of particles with high residence time. The three-dimensional geometry model was used to simulate the motion and accumulation of the particles under the magnetic field influence in anastomotic region of the coronary bypass graft. The flow patterns are evaluated both numerically and experimentally and show a good correlation in term of flow parameters like vortex length and flow stagnation point positions. Particle depositions are strongly dependent on the magnet position and consequently of the magnetic field intensity and field gradient. Increased magnetic field controlled by the magnet position induces increased particle depositions in the bypass graft anastomosis. The result shows that particle depositions depend on the bypass graft angle, and the deposition shape and particle accumulation respectively, depend by the flow pattern in the anastomosis region.

  3. Development of a Twin-Spool Turbofan Engine Simulation Using the Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS)

    NASA Technical Reports Server (NTRS)

    Zinnecker, Alicia M.; Chapman, Jeffryes W.; Lavelle, Thomas M.; Litt, Jonathan S.

    2014-01-01

    The Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS) is a tool that has been developed to allow a user to build custom models of systems governed by thermodynamic principles using a template to model each basic process. Validation of this tool in an engine model application was performed through reconstruction of the Commercial Modular Aero-Propulsion System Simulation (C-MAPSS) (v2) using the building blocks from the T-MATS (v1) library. In order to match the two engine models, it was necessary to address differences in several assumptions made in the two modeling approaches. After these modifications were made, validation of the engine model continued by integrating both a steady-state and dynamic iterative solver with the engine plant and comparing results from steady-state and transient simulation of the T-MATS and C-MAPSS models. The results show that the T-MATS engine model was accurate within 3% of the C-MAPSS model, with inaccuracy attributed to the increased dimension of the iterative solver solution space required by the engine model constructed using the T-MATS library. This demonstrates that, given an understanding of the modeling assumptions made in T-MATS and a baseline model, the T-MATS tool provides a viable option for constructing a computational model of a twin-spool turbofan engine that may be used in simulation studies.

  4. Development of a Twin-spool Turbofan Engine Simulation Using the Toolbox for Modeling and Analysis of Thermodynamic Systems (T-MATS)

    NASA Technical Reports Server (NTRS)

    Zinnecker, Alicia M.; Chapman, Jeffryes W.; Lavelle, Thomas M.; Litt, Johathan S.

    2014-01-01

    The Toolbox for Modeling and Analysis of Thermodynamic Systems (T-MATS) is a tool that has been developed to allow a user to build custom models of systems governed by thermodynamic principles using a template to model each basic process. Validation of this tool in an engine model application was performed through reconstruction of the Commercial Modular Aero-Propulsion System Simulation (C-MAPSS) (v2) using the building blocks from the T-MATS (v1) library. In order to match the two engine models, it was necessary to address differences in several assumptions made in the two modeling approaches. After these modifications were made, validation of the engine model continued by integrating both a steady-state and dynamic iterative solver with the engine plant and comparing results from steady-state and transient simulation of the T-MATS and C-MAPSS models. The results show that the T-MATS engine model was accurate within 3 of the C-MAPSS model, with inaccuracy attributed to the increased dimension of the iterative solver solution space required by the engine model constructed using the T-MATS library. This demonstrates that, given an understanding of the modeling assumptions made in T-MATS and a baseline model, the T-MATS tool provides a viable option for constructing a computational model of a twin-spool turbofan engine that may be used in simulation studies.

  5. 78 FR 35574 - Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co KG Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-13

    ... Directives; Rolls-Royce Deutschland Ltd & Co KG Turbofan Engines AGENCY: Federal Aviation Administration (FAA... directive (AD) for all Rolls-Royce Deutschland Ltd & Co KG (RRD) model Tay 650-15 turbofan engines. This...-Royce Deutschland Ltd & Co KG, Eschenweg 11, Dahlewitz, 15827 Blankenfelde-Mahlow, Germany; phone: 49...

  6. 78 FR 2197 - Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co KG Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-10

    ... Deutschland Ltd & Co KG Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final... Rolls-Royce Deutschland Ltd & Co KG (RRD) Model Tay 620-15 turbofan engines. This AD requires a one-time... Ltd & Co KG, Eschenweg 11, Dahlewitz, 15827 Blankenfelde- Mahlow, Germany; phone: 49 0...

  7. 78 FR 70198 - Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co KG Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-25

    ... Deutschland Ltd & Co KG Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final... & Co KG (RRD) model Tay 620-15, 650-15, and 651-54 turbofan engines. This AD requires a one-time... airworthiness directive (AD): 2013-23-01 Rolls-Royce Deutschland Ltd & Co KG: Amendment 39-17656; Docket No....

  8. 77 FR 39157 - Airworthiness Directives; Rolls-Royce plc Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-02

    ... Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule; request for...) models RB211-Trent 970-84, 970B-84, 972- 84, 972B-84, 977-84, 977B-84, and 980-84 turbofan engines. That... based on possible changes in wear rate. This AD was prompted by RR identifying wear beyond engine...

  9. 77 FR 69572 - Special Conditions: Embraer S.A., Model EMB-550 Airplanes; Flight Envelope Protection: High Speed...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-20

    .... The Model EMB-550 airplane is the first of a new family of jet airplanes designed for corporate flight... equipped with two Honeywell HTF7500-E medium bypass ratio turbofan engines mounted on aft fuselage pylons. Each engine produces approximately 6,540 pounds of thrust for normal takeoff. The primary...

  10. Core noise measurements on a YF-102 turbofan engine

    NASA Technical Reports Server (NTRS)

    Reshotko, M.; Karchmer, A. M.; Penko, P. F.; Mcardle, J. G.

    1977-01-01

    Core noise from a YF-102 high bypass ratio turbofan engine was investigated through the use of simultaneous measurements of internal fluctuating pressures and far field noise. Acoustic waveguide probes, located in the engine at the compressor exit, in the combustor, at the turbine exit, and in the core nozzle, were employed to measure internal fluctuating pressures. Spectra showed that the internal signals were free of tones, except at high frequency where machinery noise was present. Data obtained over a wide range of engine conditions suggest that below 60% of maximum fan speed the low frequency core noise contributes significantly to the far field noise.

  11. DESIGN POINT PERFORMANCE OF TURBOJET AND TURBOFAN ENGINE CYCLES

    NASA Technical Reports Server (NTRS)

    Vanco, M. R.

    1994-01-01

    This program is one designed for the calculation of design-point performance of turbojet and turbofan engine cycles. This program requires as input the airplane Mach number, the altitude-state equations, turbine-inlet temperature, afterburner temperature, duct burner temperature, bypass ratio, coolant flow, component efficiences, and component pressure ratios. The output yields specific thrust, specific fuel consumption, engine efficiency, and several component temperatures and pressures. The thermodynamic properties of the gas are expressed as functions of temperature and fuel-to-air ratio. The program is provided with an example case. The program has been implemented on the IBM 7094.

  12. Effect of flight loads on turbofan engine performance deterioration

    NASA Technical Reports Server (NTRS)

    Stakolich, E. G.; Jay, A.; Todd, E. S.; Kafka, P. G.; White, J. L.

    1978-01-01

    A significant percentage of high bypass ratio, turbofan engine performance deterioration was caused by an increase in operating clearance between fan/compressor and turbine blades and their outer air seals. These increased clearances resulted from rubs induced by a combination of engine power transients and aircraft flight loads. An analytical technique for predicting the effect of quasi-steady state aircraft flight loads on engine performance deterioration was developed and is presented. Thrust, aerodynamic and inertia loads were considered. Analytical results are shown and compared to actual engine test experience.

  13. Effect of flight loads on turbofan engine performance deterioration

    NASA Technical Reports Server (NTRS)

    Stakolich, E. G.; Jay, A.; Todd, E. S.; Kafka, P. G.; White, J. L.

    1979-01-01

    A significant percentage of high-bypass-ratio turbofan engine performance deterioration is caused by an increase in operating clearance between fan/compressor and turbine blades and their outer air seals. These increased clearances result from rubs induced by a combination of engine power transients and aircraft flight loads. An analytical technique for predicting the effect of quasi-steady state aircraft flight loads on engine performance deterioration has been developed and is presented. Thrust, aerodynamic and inertia loads are considered. Analytical results are shown and compared to actual engine test experience.

  14. Preliminary Study of the Fuel Saving Potential of Regenerative Turbofans for Commercial Subsonic Transports. [engine tests

    NASA Technical Reports Server (NTRS)

    Kraft, G. A.

    1975-01-01

    The fuel savings potential of regenerative turbofans was calculated and compared with that of a reference turbofan. At the design altitude of 10.67 km and Mach 0.80, the turbine-inlet-temperature of the regenerative turbofan was fixed at 1700 K while the overall pressure ratio was varied from 10 to 20. The fan pressure ratio was fixed at 1.6 and the bypass ratio varied from 8 to 10. The heat exchanger design parameters such as pressure drop and effectiveness varied from 4 to 8 percent and from 0.80 to 0.90, respectively. Results indicate a fuel savings due to regeneration of 4.1 percent and no change in takeoff gross weight.

  15. Study of Turbofan Engines Designed for Low Enery Consumption

    NASA Technical Reports Server (NTRS)

    Neitzel, R. E.; Hirschkron, R.; Johnston, R. P.

    1976-01-01

    Subsonic transport turbofan engine design and technology features which have promise of improving aircraft energy consumption are described. Task I addressed the selection and evaluation of features for the CF6 family of engines in current aircraft, and growth models of these aircraft. Task II involved cycle studies and the evaluation of technology features for advanced technology turbofans, consistent with initial service in 1985. Task III pursued the refined analysis of a specific design of an advanced technology turbofan engine selected as the result of Task II studies. In all of the above, the impact upon aircraft economics, as well as energy consumption, was evaluated. Task IV summarized recommendations for technology developments which would be necessary to achieve the improvements in energy consumption identified.

  16. Analysis of the pedestrian arching at bottleneck based on a bypassing behavior model

    NASA Astrophysics Data System (ADS)

    Tang, Ming; Jia, Hongfei; Ran, Bin; Li, Jun

    2016-07-01

    A bypassing behavior model was proposed, in which the local optimal decision behavior in the strategy level was modeled in velocity-time domain, to describe how pedestrians bypass the local obstacles considering the relative speed. The model contains (1) pedestrian visual and contact information acquisition; (2) motion state prediction of the local obstacles based on the visual and contact information; (3) pedestrian bypass strategy modeling in the velocity-time domain; (4) moving and overlapping solution. In the numerical solution, velocity domain was divided into n equal angle, the value of n ranges from 2 to infinity, the Manhattan space was refined gradually to Euclid Space accordingly, in which the movement of pedestrians was described. The model was applied to the analysis of pedestrian arching at the bottleneck in the emergent evacuation situation. (1) The results showed that the formation of the pedestrian arching at the bottleneck was deformation pressure, because many pedestrians try to pass through the bottleneck simultaneously, even in the absence of friction, the pedestrian arching still occurs; (2) In the emergent situation, we are more concerned about the bottleneck attribution of resistance to form the arching, the calculation and simulation results showed that the probability of an arching and the bottleneck width is an exponential function relationship, so when the stampede occurs in the middle of the bottleneck, the probability of arching will increase exponentially.

  17. The design and development of a mixer compound exhaust system for a quiet clean general aviation turbofan

    NASA Technical Reports Server (NTRS)

    Blackmore, W. L.; Thompson, C. E.

    1981-01-01

    Lower engine fuel consumption has become a dominant factor in turbofan engine design due to rapidly increasing fuel costs. One engine component with a large impact on engine performance is the exhaust system. Previous exhaust system studies have demonstrated the significant exhaust system efficiency gains available through mixing of the core and bypass flows. Typically, a large, costly rig and engine program are required to develop and optimize these gains. The purpose of this paper is to present the results of the low-cost design system used for the quiet, clean general aviation turbofan mixer nozzle design and development. The scale model and full-scale engine test results confirm the predicted 3 to 5% reduction in cruise fuel consumption. This unique design system, which is based on integrating advanced three-dimensional viscous numerical methods with empirical optimization techniques, is summarized and detailed comparisons with test data are presented. The ability to accurately predict relative performance of mixer systems with substantially reduced development time and cost savings is demonstrated.

  18. Turbofan gas turbine engine with variable fan outlet guide vanes

    NASA Technical Reports Server (NTRS)

    Wood, Peter John (Inventor); Zenon, Ruby Lasandra (Inventor); LaChapelle, Donald George (Inventor); Mielke, Mark Joseph (Inventor); Grant, Carl (Inventor)

    2010-01-01

    A turbofan gas turbine engine includes a forward fan section with a row of fan rotor blades, a core engine, and a fan bypass duct downstream of the forward fan section and radially outwardly of the core engine. The forward fan section has only a single stage of variable fan guide vanes which are variable fan outlet guide vanes downstream of the forward fan rotor blades. An exemplary embodiment of the engine includes an afterburner downstream of the fan bypass duct between the core engine and an exhaust nozzle. The variable fan outlet guide vanes are operable to pivot from a nominal OGV position at take-off to an open OGV position at a high flight Mach Number which may be in a range of between about 2.5-4+. Struts extend radially across a radially inwardly curved portion of a flowpath of the engine between the forward fan section and the core engine.

  19. Managing the inflammatory response after cardiopulmonary bypass: review of the studies in animal models

    PubMed Central

    Liguori, Gabriel Romero; Kanas, Alexandre Fligelman; Moreira, Luiz Felipe Pinho

    2014-01-01

    Objective To review studies performed in animal models that evaluated therapeutic interventions to inflammatory response and microcirculatory changes after cardiopulmonary bypass. Methods It was used the search strategy ("Cardiopulmonary Bypass" (MeSH)) and ("Microcirculation" (MeSH) or "Inflammation" (MeSH) or "Inflammation Mediators" (MeSH)). Repeated results, human studies, non-English language articles, reviews and studies without control were excluded. Results Blood filters, system miniaturization, specific primers regional perfusion, adequate flow and temperature and pharmacological therapies with anticoagulants, vasoactive drugs and anti-inflammatories reduced changes in microcirculation and inflammatory response. Conclusion Demonstrated efficacy in animal models establishes a perspective for evaluating these interventions in clinical practice. PMID:24896169

  20. Advanced Control Considerations for Turbofan Engine Design

    NASA Technical Reports Server (NTRS)

    Connolly, Joseph W.; Csank, Jeffrey T.; Chicatelli, Amy

    2016-01-01

    This paper covers the application of a model-based engine control (MBEC) methodology featuring a self tuning on-board model for an aircraft turbofan engine simulation. The nonlinear engine model is capable of modeling realistic engine performance, allowing for a verification of the advanced control methodology over a wide range of operating points and life cycle conditions. The on-board model is a piece-wise linear model derived from the nonlinear engine model and updated using an optimal tuner Kalman Filter estimation routine, which enables the on-board model to self-tune to account for engine performance variations. MBEC is used here to show how advanced control architectures can improve efficiency during the design phase of a turbofan engine by reducing conservative operability margins. The operability margins that can be reduced, such as stall margin, can expand the engine design space and offer potential for efficiency improvements. Application of MBEC architecture to a nonlinear engine simulation is shown to reduce the thrust specific fuel consumption by approximately 1% over the baseline design, while maintaining safe operation of the engine across the flight envelope.

  1. Numerical modeling of hemodynamics scenarios of patient-specific coronary artery bypass grafts.

    PubMed

    Ballarin, Francesco; Faggiano, Elena; Manzoni, Andrea; Quarteroni, Alfio; Rozza, Gianluigi; Ippolito, Sonia; Antona, Carlo; Scrofani, Roberto

    2017-03-13

    A fast computational framework is devised to the study of several configurations of patient-specific coronary artery bypass grafts. This is especially useful to perform a sensitivity analysis of the hemodynamics for different flow conditions occurring in native coronary arteries and bypass grafts, the investigation of the progression of the coronary artery disease and the choice of the most appropriate surgical procedure. A complete pipeline, from the acquisition of patient-specific medical images to fast parameterized computational simulations, is proposed. Complex surgical configurations employed in the clinical practice, such as Y-grafts and sequential grafts, are studied. A virtual surgery platform based on model reduction of unsteady Navier-Stokes equations for blood dynamics is proposed to carry out sensitivity analyses in a very rapid and reliable way. A specialized geometrical parameterization is employed to compare the effect of stenosis and anastomosis variation on the outcome of the surgery in several relevant cases.

  2. Active Control of Inlet Noise on the JT15D Turbofan Engine

    NASA Technical Reports Server (NTRS)

    Smith, Jerome P.; Hutcheson, Florence V.; Burdisso, Ricardo A.; Fuller, Chris R.

    1999-01-01

    This report presents the key results obtained by the Vibration and Acoustics Laboratories at Virginia Tech over the year from November 1997 to December 1998 on the Active Noise Control of Turbofan Engines research project funded by NASA Langley Research Center. The concept of implementing active noise control techniques with fuselage-mounted error sensors is investigated both analytically and experimentally. The analytical part of the project involves the continued development of an advanced modeling technique to provide prediction and design guidelines for application of active noise control techniques to large, realistic high bypass engines of the type on which active control methods are expected to be applied. Results from the advanced analytical model are presented that show the effectiveness of the control strategies, and the analytical results presented for fuselage error sensors show good agreement with the experimentally observed results and provide additional insight into the control phenomena. Additional analytical results are presented for active noise control used in conjunction with a wavenumber sensing technique. The experimental work is carried out on a running JT15D turbofan jet engine in a test stand at Virginia Tech. The control strategy used in these tests was the feedforward Filtered-X LMS algorithm. The control inputs were supplied by single and multiple circumferential arrays of acoustic sources equipped with neodymium iron cobalt magnets mounted upstream of the fan. The reference signal was obtained from an inlet mounted eddy current probe. The error signals were obtained from a number of pressure transducers flush-mounted in a simulated fuselage section mounted in the engine test cell. The active control methods are investigated when implemented with the control sources embedded within the acoustically absorptive material on a passively-lined inlet. The experimental results show that the combination of active control techniques with fuselage

  3. 78 FR 72552 - Airworthiness Directives; General Electric Company Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-03

    ... Company Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: We are adopting a new airworthiness directive (AD) for certain General Electric Company model GEnx..., contact General Electric Company, GE Aviation, Room 285, 1 Neumann Way, Cincinnati, OH 45215; phone:...

  4. Multiscale modeling and simulation of blood flow in coronary artery bypass graft surgeries

    NASA Astrophysics Data System (ADS)

    Sankaran, Sethuraman; Esmaily Moghadam, Mahdi; Kahn, Andy; Marsden, Alison

    2011-11-01

    We present a computational framework for modeling and simulation of blood flow in patients who undergo coronary artery bypass graft (CABG) surgeries. We evaluate the influence of shape on the homeostatic state, cardiac output, and other quantities of interest. We present a case study on a patient with multiple CABG. We build a patient-specific model of the blood vessels comprised of the aorta, vessels branching from the top of the aorta (brachiocephalic artery and carotids) and the coronary arteries, in addition to bypass grafts. The rest of the circulatory system is modeled using lumped parameter 0D models comprised of resistances, compliances, inertances and elastance. An algorithm is presented that computes these parameters automatically given constraints on the flow. A Finite element framework is used to compute blood flow and pressure in the 3D model to which the 0D code is coupled at the model inlets and outlets. An adaptive closed loop BC is used to capture the coupling of the various outlets of the model with inlets, and is compared with a model with fixed inlet BC. We compare and contrast the pressure, flowrate, coronary perfusion, and PV curves obtained in the different cases. Further, we compare and contrast quantities of interest such as wall shear stress, wall shear stress gradients and oscillatory shear index for different surgical geometries and discuss implications of patient-specific optimization. I would like to acknowlege AHA for funding this work.

  5. Design and evaluation of an integrated Quiet, Clean General Aviation Turbofan (QCGAT) engine and aircraft propulsion system

    NASA Technical Reports Server (NTRS)

    German, J.; Fogel, P.; Wilson, C.

    1980-01-01

    The design was based on the LTS-101 engine family for the core engine. A high bypass fan design (BPR=9.4) was incorporated to provide reduced fuel consumption for the design mission. All acoustic and pollutant emissions goals were achieved. A discussion of the preliminary design of a business jet suitable for the developed propulsion system is included. It is concluded that large engine technology can be successfully applied to small turbofans, and noise or pollutant levels need not be constraints for the design of future small general aviation turbofan engines.

  6. Turbofan Engine Simulated in a Graphical Simulation Environment

    NASA Technical Reports Server (NTRS)

    Parker, Khary I.; Guo, Ten-Huei

    2004-01-01

    Recently, there has been an increase in the development of intelligent engine technology with advanced active component control. The computer engine models used in these control studies are component-level models (CLM), models that link individual component models of state space and nonlinear algebraic equations, written in a computer language such as Fortran. The difficulty faced in performing control studies on Fortran-based models is that Fortran is not supported with control design and analysis tools, so there is no means for implementing real-time control. It is desirable to have a simulation environment that is straightforward, has modular graphical components, and allows easy access to health, control, and engine parameters through a graphical user interface. Such a tool should also provide the ability to convert a control design into real-time code, helping to make it an extremely powerful tool in control and diagnostic system development. Simulation time management is shown: Mach number versus time, power level angle versus time, altitude versus time, ambient temperature change versus time, afterburner fuel flow versus time, controller and actuator dynamics, collect initial conditions, CAD output, and component-level model: CLM sensor, CAD input, and model output. The Controls and Dynamics Technologies Branch at the NASA Glenn Research Center has developed and demonstrated a flexible, generic turbofan engine simulation platform that can meet these objectives, known as the Modular Aero-Propulsion System Simulation (MAPSS). MAPSS is a Simulink-based implementation of a Fortran-based, modern high pressure ratio, dual-spool, low-bypass, military-type variable-cycle engine with a digital controller. Simulink (The Mathworks, Natick, MA) is a computer-aided control design and simulation package allows the graphical representation of dynamic systems in a block diagram form. MAPSS is a nonlinear, non-real-time system composed of controller and actuator dynamics

  7. Patient-specific multiscale modeling of blood flow for coronary artery bypass graft surgery.

    PubMed

    Sankaran, Sethuraman; Esmaily Moghadam, Mahdi; Kahn, Andrew M; Tseng, Elaine E; Guccione, Julius M; Marsden, Alison L

    2012-10-01

    We present a computational framework for multiscale modeling and simulation of blood flow in coronary artery bypass graft (CABG) patients. Using this framework, only CT and non-invasive clinical measurements are required without the need to assume pressure and/or flow waveforms in the coronaries and we can capture global circulatory dynamics. We demonstrate this methodology in a case study of a patient with multiple CABGs. A patient-specific model of the blood vessels is constructed from CT image data to include the aorta, aortic branch vessels (brachiocephalic artery and carotids), the coronary arteries and multiple bypass grafts. The rest of the circulatory system is modeled using a lumped parameter network (LPN) 0 dimensional (0D) system comprised of resistances, capacitors (compliance), inductors (inertance), elastance and diodes (valves) that are tuned to match patient-specific clinical data. A finite element solver is used to compute blood flow and pressure in the 3D (3 dimensional) model, and this solver is implicitly coupled to the 0D LPN code at all inlets and outlets. By systematically parameterizing the graft geometry, we evaluate the influence of graft shape on the local hemodynamics, and global circulatory dynamics. Virtual manipulation of graft geometry is automated using Bezier splines and control points along the pathlines. Using this framework, we quantify wall shear stress, wall shear stress gradients and oscillatory shear index for different surgical geometries. We also compare pressures, flow rates and ventricular pressure-volume loops pre- and post-bypass graft surgery. We observe that PV loops do not change significantly after CABG but that both coronary perfusion and local hemodynamic parameters near the anastomosis region change substantially. Implications for future patient-specific optimization of CABG are discussed.

  8. 78 FR 10501 - Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co KG Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-14

    ... Deutschland Ltd & Co KG Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final... & Co KG (RRD) BR700-710A1-10 and BR700- 710A2-20 turbofan engines, and certain BR700-710C4-11 model... the following new AD: 2013-03-17 Rolls-Royce Deutschland Ltd & Co KG (Formerly Rolls-Royce...

  9. Electrical and thermal finite element modeling of arc faults in photovoltaic bypass diodes.

    SciTech Connect

    Bower, Ward Isaac; Quintana, Michael A.; Johnson, Jay

    2012-01-01

    Arc faults in photovoltaic (PV) modules have caused multiple rooftop fires. The arc generates a high-temperature plasma that ignites surrounding materials and subsequently spreads the fire to the building structure. While there are many possible locations in PV systems and PV modules where arcs could initiate, bypass diodes have been suspected of triggering arc faults in some modules. In order to understand the electrical and thermal phenomena associated with these events, a finite element model of a busbar and diode was created. Thermoelectrical simulations found Joule and internal diode heating from normal operation would not normally cause bypass diode or solder failures. However, if corrosion increased the contact resistance in the solder connection between the busbar and the diode leads, enough voltage potentially would be established to arc across micron-scale electrode gaps. Lastly, an analytical arc radiation model based on observed data was employed to predicted polymer ignition times. The model predicted polymer materials in the adjacent area of the diode and junction box ignite in less than 0.1 seconds.

  10. A three-equation bypass transition model based on the intermittency function

    NASA Astrophysics Data System (ADS)

    Ge, Xuan

    An intermittency model that is formulated in local variables is proposed for representing bypass transition in Reynolds-Averaged Navier-Stokes (RANS) computations. No external data correlation is used to fix transition. Transition is initiated by diffusion and a source term carries it to completion. A sink term is created to predict the laminar region before transition and vanishes in turbulent region. The present model is implemented in OpenFOAM, a platform for computational fluid dynamics (CFD) codes with unstructured mesh. For validation of this model, a group of test cases based on flat plate experiments have been set up for numerical simulations in OpenFOAM. It turns out that the current model is capable to predict boundary layer transition on a flat plate both with and without pressure gradients when decent agreement with the available experiment data is observed.

  11. High Bypass Turbofan Component Development. Phase II. Fan Detail Design.

    DTIC Science & Technology

    1979-12-01

    Vane metal angles ........ ..................... ... 18 22 Vane conical airfoil sections ..... ............... ... 19 23 Principal blade stresses at...31.25 deg. The number of rotor airfoils is 20 while the stator has 42 vanes . The number of vanes and the vane - blade spacing were consequences of...effect of radius change are accounted for. Figure 16 shows the blade hub, mean, and tip conical airfoil sections in engine orientation. For

  12. Performance deterioration of commercial high-bypass ratio turbofan engines

    NASA Technical Reports Server (NTRS)

    Mehalic, C. M.; Ziemianski, J. A.

    1980-01-01

    The results of engine performance deterioration investigations based on historical data, special engine tests, and specific tests to define the influence of flight loads and component clearances on performance are presented. The results of analyses of several damage mechanisms that contribute to performance deterioration such as blade tip rubs, airfoil surface roughness and erosion, and thermal distortion are also included. The significance of these damage mechanisms on component and overall engine performance is discussed.

  13. A three-equation bypass transition model based on the intermittency function

    NASA Astrophysics Data System (ADS)

    Ge, Xuan; Durbin, Paul

    2013-11-01

    An intermittency model that is formulated in local variables is proposed for representing bypass transition in Reynolds-Averaged Navier-Stokes (RANS) computations. No external data correlation is used to fix transition. Transition is initiated by diffusion and a source term carries it to completion. A sink term is created to predict the laminar region before transition and vanishes in turbulent region. For validation of this model, a group of test cases based on flat plate experiments have been set up for numerical simulations in OpenFOAM. It turns out that the current model is capable to predict boundary layer transition on a flat plate both with and without pressure gradients. Decent agreement with the available experiment data is observed. Supported by NSF Award Number 1228195.

  14. Nacelle/pylon interference study on a 1/17th-scale, twin-engine, low-wing transport model

    NASA Technical Reports Server (NTRS)

    Pendergraft, Odis C., Jr.; Ingraldi, Anthony M.; Re, Richard J.; Kariya, Timmy T.

    1989-01-01

    NASA-Langley has conducted wind tunnel tests of a twin-engine, low-wing transport aircraft configuration with 10.8-aspect ratio supercritical wing, in order to ascertain and compare the wing/nacelle interference effects of through-flow nacelled simulating 'superfan' very high bypass ratio (BPR=20) turbofans and current-technology (BPR=6) turbofans. Measurements of model forces and moments have been obtained, together with extensive external static pressure measurement on the model's wings, nacelles, and pylons in the Mach 0.5-0.8 range, at angles of attack in the -4 to +8 deg range. The superfan nacelles exhibit a significant advantage over current-technology turbofan nacelles, when the superfan's SFC gains are taken into account.

  15. Overview of ERA Ultra High Bypass Propulsor Technology Development

    NASA Technical Reports Server (NTRS)

    Hughes, Christopher

    2011-01-01

    A review of the current research being conducted under the Environmentally Responsible Aviation (ERA) Ultra High Bypass (UHB) Testing subelement is presented. The four exiting tasks under the subelement, a description of each task, and the current status of each are given. The four tasks are: 1. Collaborate with P&W to design, fabricate and test a second generation of Geared Turbofan 2. Design, fabricate and test advanced Over the Rotor acoustic treatment and acoustically treated Soft Vanes 3. Develop a Shape Memory Alloy Variable Area Nozzle concept and demonstrate prototype 4. Refurbish and update the GRC Ultra High Bypass Drive Rig Following the current task updates, an overview of three proposed additional tasks to support the existing tasks is presented. The additional tasks would allow noise reduction and noise diagnostic testing technologies to be demonstrated at TRL 4 as part of existing planned fan model testing in the NASA Glenn 9 x15 Low Speed Wind Tunnel under the ERA UHB Testing subelement.

  16. Simulating the Use of Alternative Fuels in a Turbofan Engine

    NASA Technical Reports Server (NTRS)

    Litt, Jonathan S.; Chin, Jeffrey Chevoor; Liu, Yuan

    2013-01-01

    The interest in alternative fuels for aviation has created a need to evaluate their effect on engine performance. The use of dynamic turbofan engine simulations enables the comparative modeling of the performance of these fuels on a realistic test bed in terms of dynamic response and control compared to traditional fuels. The analysis of overall engine performance and response characteristics can lead to a determination of the practicality of using specific alternative fuels in commercial aircraft. This paper describes a procedure to model the use of alternative fuels in a large commercial turbofan engine, and quantifies their effects on engine and vehicle performance. In addition, the modeling effort notionally demonstrates that engine performance may be maintained by modifying engine control system software parameters to account for the alternative fuel.

  17. Mechanistic Comparison between Gastric Bypass vs. Duodenal Switch with Sleeve Gastrectomy in Rat Models

    PubMed Central

    Kodama, Yosuke; Johannessen, Helene; Furnes, Marianne W.; Zhao, Chun-Mei; Johnsen, Gjermund; Mårvik, Ronald; Kulseng, Bård; Chen, Duan

    2013-01-01

    Background Both gastric bypass (GB) and duodenal switch with sleeve gastrectomy (DS) have been widely used as bariatric surgeries, and DS appears to be superior to GB. The aim of this study was to better understand the mechanisms leading to body weight loss by comparing these two procedures in experimental models of rats. Methods Animals were subjected to GB, DS or laparotomy (controls), and monitored by an open-circuit indirect calorimeter composed of comprehensive laboratory animal monitoring system and adiabatic bomb calorimeter. Results Body weight loss was greater after DS than GB. Food intake was reduced after DS but not GB. Energy expenditure was increased after either GB or DS. Fecal energy content was increased after DS but not GB. Conclusion GB induced body weight loss by increasing energy expenditure, whereas DS induced greater body weight loss by reducing food intake, increasing energy expenditure and causing malabsorption in rat models. PMID:24039816

  18. Heart bypass surgery

    MedlinePlus

    Off-pump coronary artery bypass; OPCAB; Beating heart surgery; Bypass surgery - heart; CABG; Coronary artery bypass graft; Coronary artery bypass surgery; Coronary bypass surgery; Coronary artery disease - CABG; CAD - CABG; Angina - ...

  19. Advanced Engine Cycles Analyzed for Turbofans With Variable-Area Fan Nozzles Actuated by a Shape Memory Alloy

    NASA Technical Reports Server (NTRS)

    Berton, Jeffrey J.

    2002-01-01

    Con) Program, has the potential to enable the next generation of efficient, quiet, very high bypass ratio turbofans. NASA Glenn Research Center's Propulsion Systems Analysis Office, along with NASA Langley Research Center's Systems Analysis Branch, conducted an independent analytical assessment of this new technology to provide strategic guidance to UEET and RevCon. A 2010-technology-level high-spool engine core was designed for this evaluation. Two families of low-spool components, one with and one without VAFN's, were designed to operate with the core. This "constant core" approach was used to hold most design parameters constant so that any performance differences between the VAFN and fixed nozzle cycles could be attributed to the VAFN technology alone. In this manner, the cycle design regimes that offer a performance payoff when VAFN's are used could be identified. The NASA analytical model of a performance-optimized VAFN turbofan with a fan pressure ratio of 1.28 is shown. Mission analyses of the engines were conducted using the notional, long-haul, advanced commercial twinjet shown. A high wing design was used to accommodate the large high-bypassratio engines. The mission fuel reduction benefit of very high bypass shape-memory-alloy VAFN aircraft was calculated to be 8.3 percent lower than a moderate bypass cycle using a conventional fixed nozzle. Shape-memory-alloy VAFN technology is currently under development in NASA's UEET and RevCon Programs.

  20. Cytoprotection by inhaled carbon monoxide before cardiopulmonary bypass in preclinical models.

    PubMed

    Loop, Torsten; Schlensak, Christian; Goebel, Ulrich

    2012-05-01

    Although a potentially toxic gaseous molecule, carbon monoxide recently gains rising scientifically and clinical interest as its beneficial effects and mechanisms of action are defined substantially in various in vitro and in vivo experiments. Its anti-inflammatory, anti-apoptotic and anti-proliferative properties but its increasing impact concerning numerous disease models in means of protection, well describe this gas as a new and challenging therapeutic alternative. In this review, we focus on the extensively analyzed advantageous value of pre- and postconditioning with inhaled carbon monoxide in the context of lung and kidney injury, induced by the low perfusion during and after cardiopulmonary bypass. Mechanisms like the heat shock response as well as an expanded view regarding toxicity and side effects are described broadly.

  1. Does littoral sand bypass the head of Mugu Submarine Canyon? - a modeling study

    USGS Publications Warehouse

    Xu, Jingping; Elias, Edwin; Kinsman, Nicole; Wang, Ping; Rosati, Julie D.; Roberts, Tiffany M.

    2011-01-01

    A newly developed sand-tracer code for the process-based model Delft3D (Deltares, The Netherlands) was used to simulate the littoral transport near the head of the Mugu Submarine Canyon in California, USA. For westerly swells, which account for more than 90% of the wave conditions in the region, the sand tracers in the downcoast littoral drift were unable to bypass the canyon head. A flow convergence near the upcoast rim of the canyon intercepts the tracers and moves them either offshore onto the shelf just west of the canyon rim (low wave height conditions) or into the canyon head (storm wave conditions). This finding supports the notion that Mugu Canyon is the true terminus of the Santa Barbara Littoral Cell.

  2. Establishment of a coculture model for studying inflammation after pediatric cardiopulmonary bypass: from bench to bedside.

    PubMed

    Wollersheim, Sonja; Fedarava, Katisaryna; Huebler, Michael; Schneiderhan-Marra, Nicole; Berger, Felix; Miera, Oliver; Schmitt, Katharina R

    2012-06-01

    Cardiopulmonary bypass (CPB) has been known to induce an inflammatory response that is influenced by various factors. Hypothermia is supposed to reduce inflammation after CPB. We developed an in vitro coculture model for CPB and compared the effects of hypothermia on the inflammatory response in the coculture model with results from a clinical prospective randomized trial. The coculture model consisted of endothelial cells and monocytes. Cells were stimulated with tumor necrosis factor (TNF)-α and exposed to deep hypothermia (20°C) or normothermia (37°C). In the clinical trial, 20 patients undergoing CPB for ventricular septum defect receive either normothermic (37°C) or mild hypothermic (32°C) CPB. We observed a significant interleukin (IL)-6 and IL-8 release in the coculture model 2 and 24 h after the experimental start. In the clinical trial, cytokines were significantly increased directly after weaning from CPB and remained elevated until 24 h. IL-8 and IL-6 secretions were similar in the hypothermic and normothermic group of the coculture model and the patients after 24 h. These results demonstrate that the inflammatory reaction observed in our coculture model is comparable with the cytokine increase in the blood of children undergoing CPB. Our coculture model could be useful for studies on the mechanisms of CPB-induced inflammation.

  3. A new model for the prediction of turbofan noise with the effect of locally and non-locally reacting liners

    NASA Astrophysics Data System (ADS)

    Sun, Xiaofeng; Wang, Xiaoyu; Du, Lin; Jing, Xiaodong

    2008-09-01

    This paper presents a unified model to study the effect of both locally and non-locally reacting liners on the sound radiation generated by fan blade rotating sources. This model is set up by the following steps. First, the spinning mode eigenfunction expansions are used to obtain the solution of sound field inside the duct, while the effect of duct liner is modeled by distributed monopole sources, thus effectively avoiding the solution of a difficult complex eigenvalue problem. Secondly, in order to avoid the estimation of the generalized impedances at the inlet and exhaust planes, a boundary element method is used to give the solution outside the duct. With the suitable boundary conditions imposed on the inlet and exhaust planes, a matrix equation is obtained, and the relevant numerical calculation shows this model can not only give a good agreement with existing results for locally reacting liner but also has a capability to predict the sound radiation from fan rotating blade sources with an arbitrary combination of locally and non-locally reacting liners.

  4. Acoustic mode measurements in the inlet of a model turbofan using a continuously rotating rake: Data collection/analysis techniques

    NASA Technical Reports Server (NTRS)

    Hall, David G.; Heidelberg, Laurence; Konno, Kevin

    1993-01-01

    The rotating microphone measurement technique and data analysis procedures are documented which are used to determine circumferential and radial acoustic mode content in the inlet of the Advanced Ducted Propeller (ADP) model. Circumferential acoustic mode levels were measured at a series of radial locations using the Doppler frequency shift produced by a rotating inlet microphone probe. Radial mode content was then computed using a least squares curve fit with the measured radial distribution for each circumferential mode. The rotating microphone technique is superior to fixed-probe techniques because it results in minimal interference with the acoustic modes generated by rotor-stator interaction. This effort represents the first experimental implementation of a measuring technique developed by T. G. Sofrin. Testing was performed in the NASA Lewis Low Speed Anechoic Wind Tunnel at a simulated takeoff condition of Mach 0.2. The design is included of the data analysis software and the performance of the rotating rake apparatus. The effect of experiment errors is also discussed.

  5. Acoustic mode measurements in the inlet of a model turbofan using a continuously rotating rake - Data collection/analysis techniques

    NASA Technical Reports Server (NTRS)

    Hall, David G.; Heidelberg, Laurence; Konno, Kevin

    1993-01-01

    The rotating microphone measurement technique and data analysis procedures are documented which are used to determine circumferential and radial acoustic mode content in the inlet of the Advanced Ducted Propeller (ADP) model. Circumferential acoustic mode levels were measured at a series of radial locations using the Doppler frequency shift produced by a rotating inlet microphone probe. Radial mode content was then computed using a least squares curve fit with the measured radial distribution for each circumferential mode. The rotating microphone technique is superior to fixed-probe techniques because it results in minimal interference with the acoustic modes generated by rotor-stator interaction. This effort represents the first experimental implementation of a measuring technique developed by T. G. Sofrin. Testing was performed in the NASA Lewis Low Speed Anechoic Wind Tunnel at a simulated takeoff condition of Mach 0.2. The design is included of the data analysis software and the performance of the rotating rake apparatus. The effect of experiment errors is also discussed.

  6. Temperature control using a heat exchanger of a cardioplegic system in cardiopulmonary bypass model for rats.

    PubMed

    Kim, Won Gon; Choi, Se Hun; Kim, Jin Hyun

    2008-12-01

    Small animal cardiopulmonary bypass (CPB) model would be a valuable tool for investigating pathophysiological and therapeutic strategies on bypass. However, the rat CPB models have a number of technical limitations. Effective maintenance and control of core temperature by heat exchanger (HE) is among them. The purpose of this study was to confirm the effect of rectal temperature maintenance and hypothermic control using a HE of cardioplegia system in CPB model for rats. The miniature circuit consisted of a reservoir, HE, membrane oxygenator, and roller pump; the static priming volume was 40 cc. In the first stage of experiment, 10 male Sprague-Dawley rats were divided into two groups; HE group was subjected to CPB with HE from a cardioplegia system, and control group was subjected to CPB with warm water circulating around the reservoir. Partial CPB was conducted at a flow rate of 40 mg/kg/min for 20 min after venous cannulation (via the internal jugular vein) and arterial cannulation (via the femoral artery). Rectal temperature was measured after anesthetic induction, after cannulation, 5, 10, 15, and 20 min after CPB. Arterial blood gas with hematocrit was also analyzed, 5 and 15 min after CPB. In the second stage with the same experimental setting, rectal temperatures were lowered in 10 rats to the target temperature of 32 degrees C. After reaching the target temperature, animals were rewarmed. Rectal temperature was measured after cannulation, 5, 10, 15, 20, 25, and 30 min after CPB. Arterial blood gas with hematocrit was also analyzed, 5 and 15 min after CPB. Rectal temperature change differed between the two groups (P < 0.01). The temperatures of the HE group were well maintained during CPB, whereas the control group was under progressive hypothermia. Rectal temperature 20 min after CPB was 36.16 +/- 0.32 degrees C in the HE group and 34.22 +/- 0.36 degrees C in the control group. In the second set of experiments, the hypothermia targeted (32 degrees C) was

  7. Modeling the Effects of Ice Accretion on the Low Pressure Compressor and the Overall Turbofan Engine System Performance

    NASA Technical Reports Server (NTRS)

    Veres, Joseph P.; Jorgenson, Philip C. E.; Wright, William B.

    2011-01-01

    The focus of this study is on utilizing a mean line compressor flow analysis code coupled to an engine system thermodynamic code, to estimate the effects of ice accretion on the low pressure compressor, and quantifying its effects on the engine system throughout a notional flight trajectory. In this paper a temperature range in which engine icing would occur was assumed. This provided a mechanism to locate potential component icing sites and allow the computational tools to add blockages due to ice accretion in a parametric fashion. Ultimately the location and level of blockage due to icing would be provided by an ice accretion code. To proceed, an engine system modeling code and a mean line compressor flow analysis code were utilized to calculate the flow conditions in the fan-core and low pressure compressor and to identify potential locations within the compressor where ice may accrete. In this study, an "additional blockage" due to the accretion of ice on the metal surfaces, has been added to the baseline aerodynamic blockage due to boundary layer, as well as the blade metal blockage. Once the potential locations of ice accretion are identified, the levels of additional blockage due to accretion were parametrically varied to estimate the effects on the low pressure compressor blade row performance operating within the engine system environment. This study includes detailed analysis of compressor and engine performance during cruise and descent operating conditions at several altitudes within the notional flight trajectory. The purpose of this effort is to develop the computer codes to provide a predictive capability to forecast the onset of engine icing events, such that they could ultimately help in the avoidance of these events.

  8. Multi-Objective Optimization of a Turbofan for an Advanced, Single-Aisle Transport

    NASA Technical Reports Server (NTRS)

    Berton, Jeffrey J.; Guynn, Mark D.

    2012-01-01

    Considerable interest surrounds the design of the next generation of single-aisle commercial transports in the Boeing 737 and Airbus A320 class. Aircraft designers will depend on advanced, next-generation turbofan engines to power these airplanes. The focus of this study is to apply single- and multi-objective optimization algorithms to the conceptual design of ultrahigh bypass turbofan engines for this class of aircraft, using NASA s Subsonic Fixed Wing Project metrics as multidisciplinary objectives for optimization. The independent design variables investigated include three continuous variables: sea level static thrust, wing reference area, and aerodynamic design point fan pressure ratio, and four discrete variables: overall pressure ratio, fan drive system architecture (i.e., direct- or gear-driven), bypass nozzle architecture (i.e., fixed- or variable geometry), and the high- and low-pressure compressor work split. Ramp weight, fuel burn, noise, and emissions are the parameters treated as dependent objective functions. These optimized solutions provide insight to the ultrahigh bypass engine design process and provide information to NASA program management to help guide its technology development efforts.

  9. Cortical and trabecular deterioration in mouse models of Roux-en-Y gastric bypass

    PubMed Central

    Yu, Elaine W.; Carmody, Jill S.; Brooks, Daniel J.; LaJoie, Scott; Kaplan, Lee M.; Bouxsein, Mary L

    2016-01-01

    Roux-en-Y gastric bypass (RYGB) is a profoundly effective treatment for severe obesity, but results in significant bone loss in patients. Developing a murine model that recapitulates this skeletal phenotype will provide a robust tool with which to study the physiologic mechanisms of this bone loss. We studied adult male C57BL/6J mice who underwent either RYGB or sham operation. Twelve weeks after surgery, we characterized biochemical bone markers (parathyroid hormone, PTH; C-telopeptide, CTX; and type 1 procollagen, P1NP) and bone microarchitectural parameters as measured by microcomputed tomography. RYGB-treated mice had significant trabecular and cortical bone deficits compared with sham-operated controls. Although adjustment for final body weight eliminated observed cortical differences, the trabecular bone volume fraction remained significantly lower in RYGB mice even after weight adjustment. PTH levels were similar between groups, but RYGB mice had significantly higher indices of bone turnover than sham controls. These data demonstrate that murine models of RYGB recapitulate patterns of bone loss and turnover that have been observed in human clinical studies. Future studies that exploit this murine model will help delineate the alterations in bone metabolism and mechanisms of bone loss after RYGB. PMID:26806052

  10. Modeling of the heat transfer in bypass transitional boundary-layer flows

    NASA Technical Reports Server (NTRS)

    Simon, Frederick F.; Stephens, Craig A.

    1991-01-01

    A low Reynolds number k-epsilon turbulence model and conditioned momentum, energy and turbulence equations were used to predict bypass transition heat transfer on a flat plate in a high-disturbance environment with zero pressure gradient. The use of conditioned equations was demonstrated to be an improvement over the use of the global-time-averaged equations for the calculation of velocity profiles and turbulence intensity profiles in the transition region of a boundary layer. The approach of conditioned equations is extended to include heat transfer and a modeling of transition events is used to predict transition onset and the extent of transition on a flat plate. The events, which describe the boundary layer at the leading edge, result in boundary-layer regions consisting of: (1) the laminar, (2) pseudolaminar, (3) transitional, and (4) turbulent boundary layers. The modeled transition events were incorporated into the TEXSTAN 2-D boundary-layer code which is used to numerically predict the heat transfer. The numerical predictions in general compared well with the experimental data and revealed areas where additional experimental information is needed.

  11. Design study of a dual-cycle turbofan-ramjet engine for a hypersonic aircraft

    NASA Technical Reports Server (NTRS)

    Zumwalt, G. W.; Suwanprasert, S.

    1983-01-01

    Computer modelling was used with two different designs of an advanced turbofan-ramjet in order to derive performance predictions. The engine would enable an aircraft to take-off, accelerate to Mach 5.0, and climb to 90,000 ft. The two concepts included a turbofan with a ramjet annularly wrapped around it and a side-by-side configuration with the ramjet having a rectangular shape and mounted alongside the turbofan. The studies were performed to model weight, length, fuel efficiency, and the requirements of the thrust/drag ratio to exceed unity over the entire flight path. LH2 would be used for fuel and to regeneratively cool the combustion chamber. Turbofan operation with and without afterburner and with and without the ramjet inlet open were examined, as were variable areas for the burners. A side-by-side configuration displayed the best performance predictions, with a ramjet mass flow being 75 percent that of the turbofan and maximum temperatures being equal.

  12. A Numerical Multiscale Framework for Modeling Patient-Specific Coronary Artery Bypass Surgeries

    NASA Astrophysics Data System (ADS)

    Ramachandra, Abhay B.; Kahn, Andrew; Marsden, Alison

    2014-11-01

    Coronary artery bypass graft (CABG) surgery is performed to revascularize diseased coronary arteries, using arterial, venous or synthetic grafts. Vein grafts, used in more than 70% of procedures, have failure rates as high as 50% in less than 10 years. Hemodynamics is known to play a key role in the mechano-biological response of vein grafts, but current non-invasive imaging techniques cannot fully characterize the hemodynamic and biomechanical environment. We numerically compute hemodynamics and wall mechanics in patient-specific 3D CABG geometries using stabilized finite element methods. The 3D patient-specific domain is coupled to a 0D lumped parameter circulatory model and parameters are tuned to match patient-specific blood pressures, stroke volumes, heart rates and heuristic flow-split values. We quantify differences in hemodynamics between arterial and venous grafts and discuss possible correlations to graft failure. Extension to a deformable wall approximation will also be discussed. The quantification of wall mechanics and hemodynamics is a necessary step towards coupling continuum models in solid and fluid mechanics with the cellular and sub-cellular responses of grafts, which in turn, should lead to a more accurate prediction of the long term outcome of CABG surgeries, including predictions of growth and remodeling.

  13. Procedure for Separating Noise Sources in Measurements of Turbofan Engine Core Noise

    NASA Technical Reports Server (NTRS)

    Miles, Jeffrey Hilton

    2006-01-01

    The study of core noise from turbofan engines has become more important as noise from other sources like the fan and jet have been reduced. A multiple microphone and acoustic source modeling method to separate correlated and uncorrelated sources has been developed. The auto and cross spectrum in the frequency range below 1000 Hz is fitted with a noise propagation model based on a source couplet consisting of a single incoherent source with a single coherent source or a source triplet consisting of a single incoherent source with two coherent point sources. Examples are presented using data from a Pratt & Whitney PW4098 turbofan engine. The method works well.

  14. Coronary Artery Bypass Grafting

    MedlinePlus

    ... from the NHLBI on Twitter. What Is Coronary Artery Bypass Grafting? Coronary artery bypass grafting (CABG) is ... bypass multiple coronary arteries during one surgery. Coronary Artery Bypass Grafting Figure A shows the location of ...

  15. Drug disposition and modelling before and after gastric bypass: immediate and controlled-release metoprolol formulations

    PubMed Central

    Gesquiere, Ina; Darwich, Adam S; Van der Schueren, Bart; de Hoon, Jan; Lannoo, Matthias; Matthys, Christophe; Rostami, Amin; Foulon, Veerle; Augustijns, Patrick

    2015-01-01

    Aims The aim of the present study was to evaluate the disposition of metoprolol after oral administration of an immediate and controlled-release formulation before and after Roux-en-Y gastric bypass (RYGB) surgery in the same individuals and to validate a physiologically based pharmacokinetic (PBPK) model for predicting oral bioavailability following RYGB. Methods A single-dose pharmacokinetic study of metoprolol tartrate 200 mg immediate release and controlled release was performed in 14 volunteers before and 6–8 months after RYGB. The observed data were compared with predicted results from the PBPK modelling and simulation of metoprolol tartrate immediate and controlled-release formulation before and after RYGB. Results After administration of metoprolol immediate and controlled release, no statistically significant difference in the observed area under the curve (AUC0–24 h) was shown, although a tendency towards an increased oral exposure could be observed as the AUC0–24 h was 32.4% [95% confidence interval (CI) 1.36, 63.5] and 55.9% (95% CI 5.73, 106) higher following RYGB for the immediate and controlled-release formulation, respectively. This could be explained by surgery-related weight loss and a reduced presystemic biotransformation in the proximal gastrointestinal tract. The PBPK values predicted by modelling and simulation were similar to the observed data, confirming its validity. Conclusions The disposition of metoprolol from an immediate-release and a controlled-release formulation was not significantly altered after RYGB; there was a tendency to an increase, which was also predicted by PBPK modelling and simulation. PMID:25917170

  16. A Pre-operative Risk Model for Post-operative Pneumonia following Coronary Artery Bypass Grafting

    PubMed Central

    Strobel, Raymond J.; Liang, Qixing; Zhang, Min; Wu, Xiaoting; Rogers, Mary A. M.; Theurer, Patricia F.; Fishstrom, Astrid B.; Harrington, Steven D.; DeLucia, Alphonse; Paone, Gaetano; Patel, Himanshu J.; Prager, Richard L.; Likosky, Donald S.

    2016-01-01

    Background Post-operative pneumonia is the most prevalent of all hospital-acquired infections following isolated coronary artery bypass grafting (CAB). Accurate prediction of a patient’s risk of this morbid complication is hindered by its low relative incidence. In an effort to support clinical decision-making and quality improvement, we developed a pre-operative prediction model for post-operative pneumonia following CAB. Methods We undertook an observational study of 16,084 patients undergoing CAB between Q3 2011 – Q2 2014 across 33 institutions participating in the Michigan Society of Thoracic and Cardiovascular Surgeons – Quality Collaborative. Variables related to patient demographics, medical history, admission status, comorbid disease, cardiac anatomy and the institution performing the procedure were investigated. Logistic regression via forwards stepwise selection (p < 0.05 threshold) was utilized to develop a risk prediction model for estimating the occurrence of pneumonia. Traditional methods were employed to assess the model’s performance. Results Post-operative pneumonia occurred in 3.30% of patients. Multivariable analysis identified 17 pre-operative factors, including: demographics, laboratory values, comorbid disease, pulmonary and cardiac function, and operative status. The final model significantly predicted the occurrence of pneumonia, and performed well (C-statistic: 0.74). These findings were confirmed via sensitivity analyses by center and clinically important sub-groups. Conclusions We identified 17 readily obtainable pre-operative variables associated with post-operative pneumonia. This model may be used to provide individualized risk estimation and to identify opportunities to reduce a patient’s pre-operative risk of pneumonia through pre-habilitation. PMID:27261082

  17. NASA / Pratt and Whitney Collaborative Partnership Research in Ultra High Bypass Cycle Propulsion Concepts

    NASA Technical Reports Server (NTRS)

    Hughes, Chris; Lord, Wed

    2008-01-01

    Current collaborative research with Pratt & Whitney on Ultra High Bypass Engine Cycle noise, performance and emissions improvements as part of the Subsonic Fixed Wing Project Ultra High Bypass Engine Partnership Element is discussed. The Subsonic Fixed Wing Project goals are reviewed, as well as their relative technology level compared to previous NASA noise program goals. Progress toward achieving the Subsonic Fixed Wing Project goals over the 2008 fiscal year by the UHB Partnership in this area of research are reviewed. The current research activity in Ultra High Bypass Engine Cycle technology, specifically the Pratt & Whitney Geared Turbofan, at NASA and Pratt & Whitney are discussed including the contributions each entity bring toward the research project, and technical plans and objectives. Pratt & Whitney Geared Turbofan current and future technology and business plans are also discussed, including the role the NASA SFW UHB partnership plays toward achieving those goals.

  18. Does Homeostasis Model Assessment of Insulin Resistance have a predictive value for post-coronary artery bypass grafting surgery outcomes?

    PubMed Central

    Aydin, Ebuzer; Ozkokeli, Mehmet

    2014-01-01

    Objective This study aims to investigate whether pre-operative Homeostasis Model Assessment Insulin Resistance (HOMA-IR) value is a predictor in non-diabetic coronary artery bypass grafting patients in combination with hemoglobin A1c, fasting blood glucose and insulin levels. Methods Eighty one patients who were admitted to Cardiovascular Surgery Clinic at our hospital between August 2012 and January 2013 with a coronary artery bypass grafting indication were included. Patients were non-diabetic with <6.3% hemoglobin A1c and were divided into two groups including treatment and control groups according to normal insulin resistance (HOMA-IR<2.5, Group A; n=41) and high insulin resistance (HOMA-IR>2.5, Group B; n=40), respectively. Pre-operative fasting blood glucose and insulin were measured and serum chemistry tests were performed. The Homeostasis Model Assessment Insulin Resistance values were calculated. Statistical analysis was performed. Results There was a statistically significant difference in fasting blood glucose and HOMA-IR values between the groups. Cross-clamping time, and cardiopulmonary bypass time were longer in Group B, compared to Group A (P=0.043 and P=0.031, respectively). Logistic regression analysis revealed that hemoglobin A1c was not a reliable determinant factor alone for pre-operative glucometabolic evaluation of non-diabetic patients. The risk factors of fasting blood glucose and cardiopulmonary bypass time were more associated with high Homeostasis Model Assessment Insulin Resistance levels. Conclusion Our study results suggest that preoperative screening of non-diabetic patients with Homeostasis Model Assessment Insulin Resistance may improve both follow-up visit schedule and short-term outcomes, and may be useful in risk stratification of the high-risk population for impending health problems. PMID:25372910

  19. A Model to Assess the Risk of Ice Accretion Due to Ice Crystal Ingestion in a Turbofan Engine and its Effects on Performance

    NASA Technical Reports Server (NTRS)

    Jorgenson, Philip C. E.; Veres, Joseph P.; Wright, William B.; Struk, Peter M.

    2013-01-01

    The occurrence of ice accretion within commercial high bypass aircraft turbine engines has been reported under certain atmospheric conditions. Engine anomalies have taken place at high altitudes that were attributed to ice crystal ingestion, partially melting, and ice accretion on the compression system components. The result was one or more of the following anomalies: degraded engine performance, engine roll back, compressor surge and stall, and flameout of the combustor. The main focus of this research is the development of a computational tool that can estimate whether there is a risk of ice accretion by tracking key parameters through the compression system blade rows at all engine operating points within the flight trajectory. The tool has an engine system thermodynamic cycle code, coupled with a compressor flow analysis code, and an ice particle melt code that has the capability of determining the rate of sublimation, melting, and evaporation through the compressor blade rows. Assumptions are made to predict the complex physics involved in engine icing. Specifically, the code does not directly estimate ice accretion and does not have models for particle breakup or erosion. Two key parameters have been suggested as conditions that must be met at the same location for ice accretion to occur: the local wet-bulb temperature to be near freezing or below and the local melt ratio must be above 10%. These parameters were deduced from analyzing laboratory icing test data and are the criteria used to predict the possibility of ice accretion within an engine including the specific blade row where it could occur. Once the possibility of accretion is determined from these parameters, the degree of blockage due to ice accretion on the local stator vane can be estimated from an empirical model of ice growth rate and time spent at that operating point in the flight trajectory. The computational tool can be used to assess specific turbine engines to their susceptibility to

  20. An Assessment of Gas Foil Bearing Scalability and the Potential Benefits to Civilian Turbofan Engines

    NASA Technical Reports Server (NTRS)

    Bruckner, Robert J.

    2010-01-01

    Over the past several years the term oil-free turbomachinery has been used to describe a rotor support system for high speed turbomachinery that does not require oil for lubrication, damping, or cooling. The foundation technology for oil-free turbomachinery is the compliant foil bearing. This technology can replace the conventional rolling element bearings found in current engines. Two major benefits are realized with this technology. The primary benefit is the elimination of the oil lubrication system, accessory gearbox, tower shaft, and one turbine frame. These components account for 8 to 13 percent of the turbofan engine weight. The second benefit that compliant foil bearings offer to turbofan engines is the capability to operate at higher rotational speeds and shaft diameters. While traditional rolling element bearings have diminished life, reliability, and load capacity with increasing speeds, the foil bearing has a load capacity proportional to speed. The traditional applications for foil bearings have been in small, lightweight machines. However, recent advancements in the design and manufacturing of foil bearings have increased their potential size. An analysis, grounded in experimentally proven operation, is performed to assess the scalability of the modern foil bearing. This analysis was coupled to the requirements of civilian turbofan engines. The application of the foil bearing to larger, high bypass ratio engines nominally at the 120 kN (approx.25000 lb) thrust class has been examined. The application of this advanced technology to this system was found to reduce mission fuel burn by 3.05 percent.

  1. Quiet Clean Short-Haul Experimental Engine (QCSEE) Over-The-Wing (OTW) propulsion system test report. Volume 2: Aerodynamics and performance. [engine performance tests to define propulsion system performance on turbofan engines

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The design and testing of the over the wing engine, a high bypass, geared turbofan engine, are discussed. The propulsion system performance is examined for uninstalled performance and installed performance. The fan aerodynamic performance and the D nozzle and reverser thrust performance are evaluated.

  2. Pharmacokinetics and a simulation model of colforsin daropate, new forskolin derivative inotropic vasodilator, in patients undergoing coronary artery bypass grafting.

    PubMed

    Kikura, Mutsuhito; Morita, Koji; Sato, Shigehito

    2004-03-01

    Colforsin daropate, a water-soluble forskolin derivative, is an adenyl cyclase activator with positive inotropic and vasodilatory effects that are useful in the treatment of ventricular dysfunction. We investigated the pharmacokinetics of colforsin daropate in cardiac surgery patients and performed simulations to determine the dosage necessary to maintain an effective plasma concentration following cardiopulmonary bypass. In six patients undergoing coronary artery bypass graft, colforsin daropate (0.01mgkg(-1)) was administered immediately after separation from cardiopulmonary bypass. Arterial blood was sampled over the next 16h and plasma concentrations of colforsin daropate and its initial active metabolite were determined by gas-chromatography. Extended nonlinear least-squares regression was used to fit a three-compartment model to each patient's data. Distribution half-life (t(1/2alpha)) was 3.9+/-1.1min, metabolic half-life (t(1/2beta)) was 1.9+/-0.7h, and elimination half-life (t(1/2gamma)) was 95.3+/-15.2h. Central-compartment volume was 591.0+/-42.8mlkg(-1), volume distribution was 2689.2+/-450.6mlkg(-1), and elimination clearance was 27.7+/-14.7mlkg(-1)min(-1). In the pharmacokinetic simulation model, 0.5, 0.75, and 1.0microgkg(-1)min(-1) continuous infusion of colforsin daropate produce effective concentration (5-10ngml(-1)) within 30, 20, and 10min, respectively following administration. An initial active metabolite of decreased rapidly to less than 1.0ngml(-1) within the first 10min.A colforsin daropate infusion of 0.7-1.0microgkg(-1)min(-1) for 10-20min followed by 0.5microgkg(-1)min(-1) continuous infusion is recommended to produce an effective concentration (5-10ngml(-1)) within 10-20min and to maintain a therapeutic concentration throughout the administration period after cardiopulmonary bypass.

  3. Minimum time acceleration of aircraft turbofan engines by using an algorithm based on nonlinear programming

    NASA Technical Reports Server (NTRS)

    Teren, F.

    1977-01-01

    Minimum time accelerations of aircraft turbofan engines are presented. The calculation of these accelerations was made by using a piecewise linear engine model, and an algorithm based on nonlinear programming. Use of this model and algorithm allows such trajectories to be readily calculated on a digital computer with a minimal expenditure of computer time.

  4. Insufflation of hydrogen gas restrains the inflammatory response of cardiopulmonary bypass in a rat model.

    PubMed

    Fujii, Yutaka; Shirai, Mikiyasu; Inamori, Shuji; Shimouchi, Akito; Sonobe, Takashi; Tsuchimochi, Hirotsugu; Pearson, James T; Takewa, Yoshiaki; Tatsumi, Eisuke; Taenaka, Yoshiyuki

    2013-02-01

    Systemic inflammatory responses in patients receiving cardiac surgery with the use of the cardiopulmonary bypass (CPB) significantly contribute to CPB-associated morbidity and mortality. We hypothesized that insufflated hydrogen gas (H₂) would provide systemic anti-inflammatory and anti-apoptotic effects during CPB, therefore reducing proinflammatory cytokine levels. In this study, we examined the protective effect of H₂ on a rat CPB model. Rats were divided into three groups: the sham operation (SHAM) group, received sternotomy only; the CPB group, which was initiated and maintained for 60 min; and the CPB + H₂ group in which H₂ was given via an oxygenator during CPB for 60 min. We collected blood samples before, 20 min, and 60 min after the initiation of CPB. We measured the serum cytokine levels of (tumor necrosis factor-α, interleukin-6, and interleukin-10) and biochemical markers (lactate dehydrogenase, aspartate aminotransferase, and alanine aminotransferase). We also measured the wet-to-dry weight (W/D) ratio of the left lung 60 min after the initiation of CPB. In the CPB group, the cytokine and biochemical marker levels significantly increased 20 min after the CPB initiation and further increased 60 min after the CPB initiation as compared with the SHAM group. In the CPB + H₂ group, however, such increases were significantly suppressed at 60 min after the CPB initiation. Although the W/D ratio in the CPB group significantly increased as compared with that in the SHAM group, such an increase was also suppressed significantly in the CPB + H₂ group. We suggest that H₂ insufflation is a possible new potential therapy for counteracting CPB-induced systemic inflammation.

  5. 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.

  6. Impact of Distinct Oxygenators on Pulsatile Energy Indicators in an Adult Cardiopulmonary Bypass Model.

    PubMed

    Griep, Lonneke M; van Barneveld, Laurentius J M; Simons, Antoine P; Boer, Christa; Weerwind, Patrick W

    2017-02-01

    The quantification of pulse energy during cardiopulmonary bypass (CPB) post-oxygenator is required prior to the evaluation of the possible beneficial effects of pulsatile flow on patient outcome. We therefore, evaluated the impact of three distinctive oxygenators on the energy indicators energy equivalent pressure (EEP) and surplus hemodynamic energy (SHE) in an adult CPB model under both pulsatile and laminar flow conditions. The pre- and post-oxygenator pressure and flow were measured at room temperature using a 40% glycerin-water mixture at flow rates of 1, 2, 3, 4, 5, and 6 L/min. The pulse settings at frequencies of 40, 50, 60, 70, and 80 beats per minute were according to the internal algorithm of the Sorin CP5 centrifugal pump. The EEP is equal to the mean pressure, hence no SHE is present under laminar flow conditions. The Quadrox-i Adult oxygenator was associated with the highest preservation of pulsatile energy irrespective of flow rates. The low pressure drop-high compliant Quadrox-i Adult oxygenator shows the best SHE performance at flow rates of 5 and 6 L/min, while the intermediate pressure drop-low compliant Fusion oxygenator and the high pressure drop-low compliant Inspire 8F oxygenator behave optimally at flow rates of 5 L/min and up to 4 L/min, respectively. In conclusion, our findings contributed to studies focusing on SHE values post-oxygenator as well as post-cannula in clinical practice. In addition, our findings may give guidance to the clinical perfusionist for oxygenator selection prior to pulsatile CPB based on the calculated flow rate for the individual patient.

  7. Bypass Flow Study

    SciTech Connect

    Richard Schultz

    2011-09-01

    The purpose of the fluid dynamics experiments in the MIR (Matched Index of-Refraction) flow system at Idaho National Laboratory (INL) is to develop benchmark databases for the assessment of Computational Fluid Dynamics (CFD) solutions of the momentum equations, scalar mixing, and turbulence models for the flow ratios between coolant channels and bypass gaps in the interstitial regions of typical prismatic standard fuel element (SFE) or upper reflector block geometries of typical Modular High-temperature Gas-cooled Reactors (MHTGR) in the limiting case of negligible buoyancy and constant fluid properties. The experiments use Particle Image Velocimetry (PIV) to measure the velocity fields that will populate the bypass flow study database.

  8. Turbofan Acoustic Propagation and Radiation

    NASA Technical Reports Server (NTRS)

    Eversman, Walter

    2000-01-01

    This document describes progress in the development of finite element codes for the prediction of near and far field acoustic radiation from the inlet and aft fan ducts of turbofan engines. The report consists of nine papers which have appeared in archival journals and conference proceedings, or are presently in review for publication. Topics included are: 1. Aft Fan Duct Acoustic Radiation; 2. Mapped Infinite Wave Envelope Elements for Acoustic Radiation in a Uniformly Moving Medium; 3. A Reflection Free Boundary Condition for Propagation in Uniform Flow Using Mapped Infinite Wave Envelope Elements; 4. A Numerical Comparison Between Multiple-Scales and FEM Solution for Sound Propagation in Lined Flow Ducts; 5. Acoustic Propagation at High Frequencies in Ducts; 6. The Boundary Condition at an Impedance Wall in a Nonuniform Duct with Potential Flow; 7. A Reverse Flow Theorem and Acoustic Reciprocity in Compressible Potential Flows; 8. Reciprocity and Acoustics Power in One Dimensional Compressible Potential Flows; and 9. Numerical Experiments on Acoustic Reciprocity in Compressible Potential Flows.

  9. Factors which influence the behavior of turbofan forced mixer nozzles

    NASA Technical Reports Server (NTRS)

    Anderson, B. H.; Povinelli, L. A.

    1981-01-01

    A finite difference procedure was used to compute the mixing for three experimentally tested mixer geometries. Good agreement was obtained between analysis and experiment when the mechanisms responsible for secondary flow generation were properly modeled. Vorticity generation due to flow turning and vorticity generated within the centerbody lobe passage were found to be important. Results are presented for two different temperature ratios between fan and core streams and for two different free stream turbulence levels. It was concluded that the dominant mechanisms in turbofan mixers is associated with the secondary flows arising within the lobe region and their development within the mixing section.

  10. Sheep (Ovis aries) as a Model for Cardiovascular Surgery and Management before, during, and after Cardiopulmonary Bypass

    PubMed Central

    DiVincenti, Louis; Westcott, Robin; Lee, Candice

    2014-01-01

    Because of its similarity to humans in important respects, sheep (Ovis aries) are a common animal model for translational research in cardiovascular surgery. However, some unique aspects of sheep anatomy and physiology present challenges to its use in these complicated experiments. In this review, we discuss relevant anatomy and physiology of sheep and discuss management before, during, and after procedures requiring cardiopulmonary bypass to provide a concise source of information for veterinarians, technicians, and researchers developing and implementing protocols with this model. PMID:25255065

  11. Noise Benefits of Increased Fan Bypass Nozzle Area

    NASA Technical Reports Server (NTRS)

    Woodward, Richard P.; Hughes, Christopher E.

    2004-01-01

    An advanced model turbofan (typical of current engine technology) was tested in the NASA Glenn 9 by 15 Foot Low Speed Wind Tunnel (9-by 15-Foot LSWT) to explore far field acoustic effects of increased bypass nozzle area. This fan stage test was part of the NASA Glenn Fan Broadband Source Diagnostic Test, second entry (SDT2) which acquired aeroacoustic results over a range of test conditions. The baseline nozzle was sized to produce maximum stage performance for the engine at a high altitude, cruise point condition. However, the wind tunnel testing is conducted near sea level conditions. Therefore, in order to simulate and obtain performance at other aircraft operating conditions, two additional nozzles were designed and tested-one with a +5 percent increase in weight flow (+5.4 percent increase in nozzle area compared with the baseline nozzle), sized to simulate the performance at the stage design point conditions, and the other with a +7.5 percent increase in weight flow (+10.9 percent increase in nozzle area), sized for maximum weight flow with a fixed nozzle at sea level conditions. Measured acoustic benefits with increased nozzle area were very encouraging, showing overall sound power level (OAPWL) reductions of 2 or more dB while the stage thrust actually increased by several percentage points except fro the most open nozzle at takeoff rotor speed where stage performance decreased. These noise reduction benefits were seen to primarily affect broadband noise, and were evident throughout the range of measured sideline angles.

  12. Aero-acoustic tests of duct-burning turbofan exhaust nozzles

    NASA Technical Reports Server (NTRS)

    Kozlowski, H.; Packman, A. B.

    1976-01-01

    The acoustic and aerodynamic characteristics of several exhaust systems suitable for duct burning turbofan engines are evaluated. Scale models representing unsuppressed coannular exhaust systems are examined statically under varying exhaust conditions. Ejectors with both hardwall and acoustically treated inserts are investigated.

  13. 78 FR 17079 - Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co KG Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-20

    ... 2012-NE-36-AD; Amendment 39-17396; AD 2013-06-01] RIN 2120-AA64 Airworthiness Directives; Rolls-Royce... rule. SUMMARY: We are adopting a new airworthiness directive (AD) for certain Rolls-Royce Deutschland Ltd & Co KG (RRD) models Tay 620-15 and Tay 650-15 turbofan engines. This AD was prompted by...

  14. The impact of uncertainty on shape optimization of idealized bypass graft models in unsteady flow

    NASA Astrophysics Data System (ADS)

    Sankaran, Sethuraman; Marsden, Alison L.

    2010-12-01

    It is well known that the fluid mechanics of bypass grafts impacts biomechanical responses and is linked to intimal thickening and plaque deposition on the vessel wall. In spite of this, quantitative information about the fluid mechanics is not currently incorporated into surgical planning and bypass graft design. In this work, we use a derivative-free optimization technique for performing systematic design of bypass grafts. The optimization method is coupled to a three-dimensional pulsatile Navier-Stokes solver. We systematically account for inevitable uncertainties that arise in cardiovascular simulations, owing to noise in medical image data, variable physiologic conditions, and surgical implementation. Uncertainties in the simulation input parameters as well as shape design variables are accounted for using the adaptive stochastic collocation technique. The derivative-free optimization framework is coupled with a stochastic response surface technique to make the problem computationally tractable. Two idealized numerical examples, an end-to-side anastomosis, and a bypass graft around a stenosis, demonstrate that accounting for uncertainty significantly changes the optimal graft design. Results show that small changes in the design variables from their optimal values should be accounted for in surgical planning. Changes in the downstream (distal) graft angle resulted in greater sensitivity of the wall-shear stress compared to changes in the upstream (proximal) angle. The impact of cost function choice on the optimal solution was explored. Additionally, this work represents the first use of the stochastic surrogate management framework method for robust shape optimization in a fully three-dimensional unsteady Navier-Stokes design problem.

  15. Tabulated pressure measurements on a large subsonic transport model airplane with high bypass ratio, powered, fan jet engines

    NASA Technical Reports Server (NTRS)

    Flechner, S. G.; Patterson, J. C., Jr.

    1972-01-01

    An experimental wind-tunnel investigation to determine the aerodynamic interference and the jet-wake interference associated with the wing, pylon, and high-bypass-ratio, powered, fan-jet model engines has been conducted on a typical high-wing logistics transport airplane configuration. Pressures were measured on the wing and pylons and on the surfaces of the engine fan cowl, turbine cowl, and plug. Combinations of wing, pylons, engines, and flow-through nacelles were tested, and the pressure coefficients are presented in tabular form. Tests were conducted at Mach numbers from 0.700 to 0.825 and angles of attack from -2 to 4 deg.

  16. Advanced Turbofan Duct Liner Concepts

    NASA Technical Reports Server (NTRS)

    Bielak, Gerald W.; Premo, John W.; Hersh, Alan S.

    1999-01-01

    The Advanced Subsonic Technology Noise Reduction Program goal is to reduce aircraft noise by 10 EPNdB by the year 2000 relative, to 1992 technology. The improvement goal for nacelle attenuation is 25% relative to 1992 technology by 1997 and 50% by 2000. The Advanced Turbofan Duct Liner Concepts Task work by Boeing presented in this document was in support of these goals. The basis for the technical approach was a Boeing study conducted in 1993-94 under NASA/FAA contract NAS1-19349, Task 6, investigating broadband acoustic liner concepts. As a result of this work, it was recommended that linear double layer, linear and perforate triple layer, parallel element, and bulk absorber liners be further investigated to improve nacelle attenuations. NASA LaRC also suggested that "adaptive" liner concepts that would allow "in-situ" acoustic impedance control also be considered. As a result, bias flow and high-temperature liner concepts were also added to the investigation. The major conclusion from the above studies is that improvements in nacelle liner average acoustic impedance characteristics alone will not result in 25% increased nacelle noise reduction relative to 1992 technology. Nacelle design advancements currently being developed by Boeing are expected to add 20-40% more acoustic lining to hardwall regions in current inlets, which is predicted to result in and additional 40-80% attenuation improvement. Similar advancements are expected to allow 10-30% more acoustic lining in current fan ducts with 10-30% more attenuation expected. In addition, Boeing is currently developing a scarf inlet concept which is expected to give an additional 40-80% attenuation improvement for equivalent lining areas.

  17. Energy Efficient Engine program advanced turbofan nacelle definition study

    NASA Technical Reports Server (NTRS)

    Howe, David C.; Wynosky, T. A.

    1985-01-01

    Advanced, low drag, nacelle configurations were defined for some of the more promising propulsion systems identified in the earlier Benefit/Cost Study, to assess the benefits associated with these advanced technology nacelles and formulate programs for developing these nacelles and low volume thrust reversers/spoilers to a state of technology readiness in the early 1990's. The study results established the design feasibility of advanced technology, slim line nacelles applicable to advanced technology, high bypass ratio turbofan engines. Design feasibility was also established for two low volume thrust reverse/spoiler concepts that meet or exceed the required effectiveness for these engines. These nacelle and thrust reverse/spoiler designs were shown to be applicable in engines with takeoff thrust sizes ranging from 24,000 to 60,000 pounds. The reduced weight, drag, and cost of the advanced technology nacelle installations relative to current technology nacelles offer a mission fuel burn savings ranging from 3.0 to 4.5 percent and direct operating cost plus interest improvements from 1.6 to 2.2 percent.

  18. Preliminary study of advanced turbofans for low energy consumption

    NASA Technical Reports Server (NTRS)

    Knip, G.

    1975-01-01

    This analysis determines the effect of higher overall engine pressure ratios (OPR's), bypass ratios (BPR's), and turbine rotor-inlet temperature on a Mach-0.85 transport having a range of 5556 km (3000 nmi) and carrying a payload of 18144 kg (40,000 lbs-200 passengers). Sideline noises (jet plus fan) of between 91 and 106 EPNdB (FAR36) are considered. Takeoff gross weight (TOGW), fuel consumption (kg/pass. km) and direct operating cost (DOC) are used at the figures of merit. Based on predicted 1985 levels of engine technology and a noise goal of 96 EPNdB, the higher-OPR engine results in an airplane that is 18 percent lighter in terms of TOGW, uses 22.3 percent less fuel, and has a 14.7 percent lower DOC than a comparable airplane powered by a current turbofan. Cooling the compressor bleed air and lowering the cruise Mach number appear attractive in terms of further improving the figures of merit.

  19. Gastric bypass surgery - discharge

    MedlinePlus

    Bariatric surgery - gastric bypass - discharge; Roux-en-Y gastric bypass - discharge; Gastric bypass - Roux-en-Y - discharge; Obesity ... Gloy VL, Briel M, Bhatt DL, et al. Bariatric surgery versus non-surgical treatment for obesity: a systematic ...

  20. Multi-Fidelity Simulation of a Turbofan Engine With Results Zoomed Into Mini-Maps for a Zero-D Cycle Simulation

    NASA Technical Reports Server (NTRS)

    Turner, Mark G.; Reed, John A.; Ryder, Robert; Veres, Joseph P.

    2004-01-01

    A Zero-D cycle simulation of the GE90-94B high bypass turbofan engine has been achieved utilizing mini-maps generated from a high-fidelity simulation. The simulation utilizes the Numerical Propulsion System Simulation (NPSS) thermodynamic cycle modeling system coupled to a high-fidelity full-engine model represented by a set of coupled 3D computational fluid dynamic (CFD) component models. Boundary conditions from the balanced, steady state cycle model are used to define component boundary conditions in the full-engine model. Operating characteristics of the 3D component models are integrated into the cycle model via partial performance maps generated from the CFD flow solutions using one-dimensional mean line turbomachinery programs. This paper highlights the generation of the high-pressure compressor, booster, and fan partial performance maps, as well as turbine maps for the high pressure and low pressure turbine. These are actually "mini-maps" in the sense that they are developed only for a narrow operating range of the component. Results are compared between actual cycle data at a take-off condition and the comparable condition utilizing these mini-maps. The mini-maps are also presented with comparison to actual component data where possible.

  1. DYNGEN: A program for calculating steady-state and transient performance of turbojet and turbofan engines

    NASA Technical Reports Server (NTRS)

    Sellers, J. F.; Daniele, C. J.

    1975-01-01

    The DYNGEN, a digital computer program for analyzing the steady state and transient performance of turbojet and turbofan engines, is described. The DYNGEN is based on earlier computer codes (SMOTE, GENENG, and GENENG 2) which are capable of calculating the steady state performance of turbojet and turbofan engines at design and off-design operating conditions. The DYNGEN has the combined capabilities of GENENG and GENENG 2 for calculating steady state performance; to these the further capability for calculating transient performance was added. The DYNGEN can be used to analyze one- and two-spool turbojet engines or two- and three-spool turbofan engines without modification to the basic program. A modified Euler method is used by DYNGEN to solve the differential equations which model the dynamics of the engine. This new method frees the programmer from having to minimize the number of equations which require iterative solution. As a result, some of the approximations normally used in transient engine simulations can be eliminated. This tends to produce better agreement when answers are compared with those from purely steady state simulations. The modified Euler method also permits the user to specify large time steps (about 0.10 sec) to be used in the solution of the differential equations. This saves computer execution time when long transients are run. Examples of the use of the program are included, and program results are compared with those from an existing hybrid-computer simulation of a two-spool turbofan.

  2. Kalman Filtering with Inequality Constraints for Turbofan Engine Health Estimation

    NASA Technical Reports Server (NTRS)

    Simon, Dan; Simon, Donald L.

    2003-01-01

    Kalman filters are often used to estimate the state variables of a dynamic system. However, in the application of Kalman filters some known signal information is often either ignored or dealt with heuristically. For instance, state variable constraints (which may be based on physical considerations) are often neglected because they do not fit easily into the structure of the Kalman filter. This paper develops two analytic methods of incorporating state variable inequality constraints in the Kalman filter. The first method is a general technique of using hard constraints to enforce inequalities on the state variable estimates. The resultant filter is a combination of a standard Kalman filter and a quadratic programming problem. The second method uses soft constraints to estimate state variables that are known to vary slowly with time. (Soft constraints are constraints that are required to be approximately satisfied rather than exactly satisfied.) The incorporation of state variable constraints increases the computational effort of the filter but significantly improves its estimation accuracy. The improvement is proven theoretically and shown via simulation results. The use of the algorithm is demonstrated on a linearized simulation of a turbofan engine to estimate health parameters. The turbofan engine model contains 16 state variables, 12 measurements, and 8 component health parameters. It is shown that the new algorithms provide improved performance in this example over unconstrained Kalman filtering.

  3. Aerothermodynamic cycle analysis of a dual-spool, separate-exhaust turbofan engine with an interstage turbine burner

    NASA Astrophysics Data System (ADS)

    Liew, Ka Heng

    This study focuses on a specific engine, i.e., a dual-spool, separate-flow turbofan engine with an Interstage Turbine Burner (ITB). This conventional turbofan engine has been modified to include a secondary isobaric burner, i.e., ITB, in a transition duct between the high-pressure turbine and the low-pressure turbine. The preliminary design phase for this modified engine starts with the aerothermodynamics cycle analysis is consisting of parametric (i.e., on-design) and performance ( i.e., off-design) cycle analyses. In parametric analysis, the modified engine performance parameters are evaluated and compared with baseline engine in terms of design limitation (maximum turbine inlet temperature), flight conditions (such as flight Mach condition, ambient temperature and pressure), and design choices (such as compressor pressure ratio, fan pressure ratio, fan bypass ratio etc.). A turbine cooling model is also included to account for the effect of cooling air on engine performance. The results from the on-design analysis confirmed the advantage of using ITB, i.e., higher specific thrust with small increases in thrust specific fuel consumption, less cooling air, and less NOx production, provided that the main burner exit temperature and ITB exit temperature are properly specified. It is also important to identify the critical ITB temperature, beyond which the ITB is turned off and has no advantage at all. With the encouraging results from parametric cycle analysis, a detailed performance cycle analysis of the identical engine is also conducted for steady-state engine performance prediction. The results from off-design cycle analysis show that the ITB engine at full throttle setting has enhanced performance over baseline engine. Furthermore, ITB engine operating at partial throttle settings will exhibit higher thrust at lower specific fuel consumption and improved thermal efficiency over the baseline engine. A mission analysis is also presented to predict the fuel

  4. A study to estimate and compare the total particulate matter emission indices (EIN) between traditional jet fuel and two blends of Jet A/Camelina biofuel used in a high by-pass turbofan engine: A case study of Honeywell TFE-109 engine

    NASA Astrophysics Data System (ADS)

    Shila, Jacob Joshua Howard

    and JT15D engines' families as representatives of other engines with rated thrust of 6000 pounds or below. The results of this study may be used to add to the knowledge of PM emission data that has been collected in other research studies. This study was quantitative in nature. Three factors were designated which were the types of fuels studied. The TFE-109 turbofan engine was the experimental subject. The independent variable was the engine thrust setting while the response variable was the emission index. Four engine runs were conducted for each fuel. In each engine run, four engine thrust settings were observed. The four engine thrust levels were 10%, 30%, 85%, and 100% rated thrusts levels. Therefore, for each engine thrust settings, there four replicates. The experiments were conducted using a TFE-109 engine test cell located in the Niswonger Aviation Technology building at the Purdue University Airport. The testing facility has the capability to conduct the aircraft PM emissions tests. Due to the equipment limitations, the study was limited to observe total PM emissions instead of specifically measuring the non-volatile PM emissions. The results indicate that the emissions indices of the blended biofuels were not statistically significantly lower compared to the emissions of the traditional jet fuel at rated thrust levels of 100% and 85% of TFE-109 turbofan engine. However, the emission indices for the 50%Jet A - 50%Camelina biofuel blend were statistically significantly lower compared to the emission indices of the 100% Jet A fuel at 10% and 30% engine rated thrusts levels of TFE-109 engine. The emission indices of the 50%-50% biofuel blend were lower by reductions of 15% and 17% at engine rated thrusts of 10% and 30% respectively compared to the emissions indices of the traditional jet fuel at the same engine thrust levels. Experimental modifications in future studies may provide estimates of the emissions indices range for this particular engine these

  5. Surgical Models of Roux-en-Y Gastric Bypass Surgery and Sleeve Gastrectomy in Rats and Mice

    PubMed Central

    Bruinsma, Bote G.; Uygun, Korkut; Yarmush, Martin L.; Saeidi, Nima

    2015-01-01

    Bariatric surgery is the only definitive solution currently available for the present obesity pandemic. These operations typically involve reconfiguration of gastrointestinal tract anatomy and impose profound metabolic and physiological benefits, such as substantially reducing body weight and ameliorating type II diabetes. Therefore, animal models of these surgeries offer unique and exciting opportunities to delineate the underlying mechanisms that contribute to the resolution of obesity and diabetes. Here we describe a standardized procedure for mouse and rat models of Roux-en-Y gastric bypass (80–90 minutes operative time) and sleeve gastrectomy (30–45 minutes operative time), which, to a high degree resemble operations in human. We also provide detailed protocols for both pre- and post-operative techniques that ensure a high success rate in the operations. These protocols provide the opportunity to mechanistically investigate the systemic effects of the surgical interventions, such as regulation of body weight, glucose homeostasis, and gut microbiome. PMID:25719268

  6. Rotating Rake Turbofan Duct Mode Measurement System

    NASA Technical Reports Server (NTRS)

    Sutliff, Daniel L.

    2005-01-01

    An experimental measurement system was developed and implemented by the NASA Glenn Research Center in the 1990s to measure turbofan duct acoustic modes. The system is a continuously rotating radial microphone rake that is inserted into the duct. This Rotating Rake provides a complete map of the acoustic duct modes present in a ducted fan and has been used on a variety of test articles: from a low-speed, concept test rig, to a full-scale production turbofan engine. The Rotating Rake has been critical in developing and evaluating a number of noise reduction concepts as well as providing experimental databases for verification of several aero-acoustic codes. More detailed derivation of the unique Rotating Rake equations are presented in the appendix.

  7. Noise Reduction Technologies for Turbofan Engines

    NASA Technical Reports Server (NTRS)

    Huff, Dennis L.

    2007-01-01

    Significant progress continues to be made with noise reduction for turbofan engines. NASA has conducted and sponsored research aimed at reducing noise from commercial aircraft. Since it takes many years for technologies to be developed and implemented, it is important to have aggressive technology goals that lead the target entry into service dates. Engine noise is one of the major contributors to the overall sound levels as aircraft operate near airports. Turbofan engines are commonly used on commercial transports due to their advantage for higher performance and lower noise. The noise reduction comes from combinations of changes to the engine cycle parameters and low noise design features. In this paper, an overview of major accomplishments from recent NASA research programs for engine noise will be given.

  8. PARTICLE IMAGE VELOCIMETRY MEASUREMENTS IN A REPRESENTATIVE GAS-COOLED PRISMATIC REACTOR CORE MODEL: FLOW IN THE COOLANT CHANNELS AND INTERSTITIAL BYPASS GAPS

    SciTech Connect

    Thomas E. Conder; Richard Skifton; Ralph Budwig

    2012-11-01

    Core bypass flow is one of the key issues with the prismatic Gas Turbine-Modular Helium Reactor, and it refers to the coolant that navigates through the interstitial, non-cooling passages between the graphite fuel blocks instead of traveling through the designated coolant channels. To determine the bypass flow, a double scale representative model was manufactured and installed in the Matched Index-of-Refraction flow facility; after which, stereo Particle Image Velocimetry (PIV) was employed to measure the flow field within. PIV images were analyzed to produce vector maps, and flow rates were calculated by numerically integrating over the velocity field. It was found that the bypass flow varied between 6.9-15.8% for channel Reynolds numbers of 1,746 and 4,618. The results were compared to computational fluid dynamic (CFD) pre-test simulations. When compared to these pretest calculations, the CFD analysis appeared to under predict the flow through the gap.

  9. Hybrid Wing Body Shielding Studies Using an Ultrasonic Configurable Fan Artificial Noise Source Generating Typical Turbofan Modes

    NASA Technical Reports Server (NTRS)

    Sutliff, Daniel L.; Brown, Cliff; Walker, Bruce E.

    2014-01-01

    An Ultrasonic Configurable Fan Artificial Noise Source (UCFANS) was designed, built, and tested in support of the NASA Langley Research Center's 14x22 wind tunnel test of the Hybrid Wing Body (HWB) full 3-D 5.8% scale model. The UCFANS is a 5.8% rapid prototype scale model of a high-bypass turbofan engine that can generate the tonal signature of proposed engines using artificial sources (no flow). The purpose of the test was to provide an estimate of the acoustic shielding benefits possible from mounting the engine on the upper surface of an HWB aircraft using the projected signature of the engine currently proposed for the HWB. The modal structures at the rating points were generated from inlet and exhaust nacelle configurations - a flat plate model was used as the shielding surface and vertical control surfaces with correct plan form shapes were also tested to determine their additional impact on shielding. Radiated acoustic data were acquired from a traversing linear array of 13 microphones, spanning 36 inches. Two planes perpendicular, and two planes parallel, to the axis of the nacelle were acquired from the array sweep. In each plane the linear array traversed 4 sweeps, for a total span of 168 inches acquired. The resolution of the sweep is variable, so that points closer to the model are taken at a higher resolution. Contour plots of Sound Pressure Levels, and integrated Power Levels, from nacelle alone and shielded configurations are presented in this paper; as well as the in-duct mode power levels.

  10. Hybrid Wing Body Shielding Studies Using an Ultrasonic Configurable Fan Artificial Noise Source Generating Typical Turbofan Modes

    NASA Technical Reports Server (NTRS)

    Sutliff, Daniel l.; Brown, Clifford A.; Walker, Bruce E.

    2014-01-01

    An Ultrasonic Configurable Fan Artificial Noise Source (UCFANS) was designed, built, and tested in support of the NASA Langley Research Center's 14- by 22-ft wind tunnel test of the Hybrid Wing Body (HWB) full 3-D 5.8 percent scale model. The UCFANS is a 5.8 percent rapid prototype scale model of a high-bypass turbofan engine that can generate the tonal signature of proposed engines using artificial sources (no flow). The purpose of the test was to provide an estimate of the acoustic shielding benefits possible from mounting the engine on the upper surface of an HWB aircraft using the projected signature of the engine currently proposed for the HWB. The modal structures at the rating points were generated from inlet and exhaust nacelle configurations--a flat plate model was used as the shielding surface and vertical control surfaces with correct plan form shapes were also tested to determine their additional impact on shielding. Radiated acoustic data were acquired from a traversing linear array of 13 microphones, spanning 36 in. Two planes perpendicular, and two planes parallel, to the axis of the nacelle were acquired from the array sweep. In each plane the linear array traversed four sweeps, for a total span of 168 in. acquired. The resolution of the sweep is variable, so that points closer to the model are taken at a higher resolution. Contour plots of Sound Pressure Levels, and integrated Power Levels, from nacelle alone and shielded configurations are presented in this paper; as well as the in-duct mode power levels

  11. 77 FR 3088 - Airworthiness Directives; General Electric Company Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-23

    ...-10] RIN 2120-AA64 Airworthiness Directives; General Electric Company Turbofan Engines AGENCY: Federal... directive (AD) for General Electric Company (GE) CF34-10E series turbofan engines. This AD was prompted by a... center vent tube) support ring and on the inside diameter of the fan drive shaft at the mating...

  12. 78 FR 44899 - Airworthiness Directives; General Electric Company Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-25

    ... Company Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed... Electric Company (GE) GE90-110B1 and -115B turbofan engines. This proposed AD was prompted by multiple... AD to prevent failure of the affected fuel supply tube, fuel leakage, engine fire, and damage to...

  13. 78 FR 76045 - Airworthiness Directives; General Electric Company Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-16

    ... Company Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule; request... (GE) GE90-110B1 and GE90-115B turbofan engines with certain high pressure compressor (HPC) rotor stage... are issuing this AD to prevent failure of a critical life-limited rotating engine part, which...

  14. 77 FR 58471 - Airworthiness Directives; General Electric Company Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-21

    ... Company Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule; request... GEnx-2B67B turbofan engines. This AD requires initial and repetitive ultrasonic inspections (UI) of... resulting in one or more engine failure(s) and possible loss of the airplane. DATES: This AD is...

  15. Study of turbofan engines designed for low energy consumption

    NASA Technical Reports Server (NTRS)

    Gray, D. E.

    1976-01-01

    The near-term technology improvements which can reduce the fuel consumed in the JT9D, JT8D, and JT3D turbofans in commercial fleet operation through the 1980's are identified. Projected technology advances are identified and evaluated for new turbofans to be developed after 1985. Programs are recommended for developing the necessary technology.

  16. 77 FR 48110 - Airworthiness Directives; General Electric Company Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-13

    ... Company Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed... certain General Electric Company (GE) CF6-80C2 series turbofan engines. The existing AD requires... additional reports of fuel leaks and two reports of engine fire due to mis-assembled supporting brackets...

  17. 77 FR 42424 - Airworthiness Directives; Pratt & Whitney Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-19

    ... Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: We are... turbofan engines. That AD currently requires removing the 15th stage high-pressure compressor (HPC) disk... stage HPC disk, uncontained engine failure, and damage to the airplane. DATES: This AD is...

  18. 77 FR 4650 - Airworthiness Directives; General Electric Company Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-31

    ... Company Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY...-45 and CF6-50 series turbofan engines with certain low-pressure turbine (LPT) rotor stage 3 disks..., engine checks, and vibration surveys. This new AD retains the requirements of the two ADs...

  19. 77 FR 15939 - Airworthiness Directives; Pratt & Whitney Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-19

    ... Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: We are superseding an existing airworthiness directive (AD) for all Pratt & Whitney (PW) JT9D series turbofan engines... the JT9D series engines ALS sections of the manufacturer's ICA. This AD was prompted by the need...

  20. 76 FR 72353 - Airworthiness Directives; Pratt & Whitney Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-23

    ... Directives; Pratt & Whitney Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION...) turbofan engines. This proposed AD was prompted by reports of five engine in-flight shutdowns and seven unplanned engine removals. This proposed AD would require inspections, cleaning, and engine modifications...

  1. 77 FR 54791 - Airworthiness Directives; Pratt & Whitney Division Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-06

    ... Division Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY...'' and PW4000-100'' turbofan engines having a 1st stage high-pressure turbine (HPT) seal support, part..., including 15 in-flight engine shutdowns. This AD requires removal and replacement of the 1st stage HPT...

  2. 77 FR 30926 - Airworthiness Directives; Pratt & Whitney Division Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-24

    ... Airworthiness Directives; Pratt & Whitney Division Turbofan Engines AGENCY: Federal Aviation Administration (FAA..., PW4164, PW4168, PW4168A, PW4460, and PW4462 turbofan engines. The existing AD currently requires initial..., Pratt & Whitney has developed a redesigned HPC drum rotor disk assembly for certain affected...

  3. 78 FR 19628 - Airworthiness Directives; General Electric Company Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-02

    ... Company Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed... Electric Company (GE) GE90-76B, -85B, -90B, -94B, - 110B1, and -115B turbofan engines. This proposed AD was... prevent failure of the stage 1 HPT stator shrouds, resulting in in-flight shutdown of one or more...

  4. 77 FR 76977 - Airworthiness Directives; General Electric Company Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-31

    ... Electric Company Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Supplemental... proposed airworthiness directive (AD) for certain General Electric Company (GE) CF6-80C2 series turbofan engines. That NPRM proposed to supersede an AD that required replacement of fuel tubes connected to...

  5. Preliminary evaluation of a heat pipe heat exchanger on a regenerative turbofan

    NASA Technical Reports Server (NTRS)

    Kraft, G. A.

    1975-01-01

    A preliminary evaluation was made of a regenerative turbofan engine using a heat pipe heat exchanger. The heat exchanger had an effectiveness of 0.70, a pressure drop of 3 percent on each side, and used sodium for the working fluid in the stainless steel heat pipes. The engine was compared to a reference turbofan engine originally designed for service in 1979. Both engines had a bypass ratio of 4.5 and a fan pressure ratio of 2.0. The design thrust of the engines was in the 4000 N range at a cruise condition of Mach 0.98 and 11.6 km. It is shown that heat pipe heat exchangers of this type cause a large weight and size problem for the engine. The penalties were too severe to be overcome by the small uninstalled fuel consumption advantage. The type of heat exchanger should only be considered for small airflow engines in flight applications. Ground applications might prove more suitable and flexible.

  6. Aircraft Turbofan Engine Health Estimation Using Constrained Kalman Filtering

    NASA Technical Reports Server (NTRS)

    Simon, Dan; Simon, Donald L.

    2003-01-01

    Kalman filters are often used to estimate the state variables of a dynamic system. However, in the application of Kalman filters some known signal information is often either ignored or dealt with heuristically. For instance, state variable constraints (which may be based on physical considerations) are often neglected because they do not fit easily into the structure of the Kalman filter. This paper develops an analytic method of incorporating state variable inequality constraints in the Kalman filter. The resultant filter is a combination of a standard Kalman filter and a quadratic programming problem. The incorporation of state variable constraints increases the computational effort of the filter but significantly improves its estimation accuracy. The improvement is proven theoretically and shown via simulation results obtained from application to a turbofan engine model. This model contains 16 state variables, 12 measurements, and 8 component health parameters. It is shown that the new algorithms provide improved performance in this example over unconstrained Kalman filtering.

  7. Simulating Effects of High Angle of Attack on Turbofan Engine Performance

    NASA Technical Reports Server (NTRS)

    Liu, Yuan; Claus, Russell W.; Litt, Jonathan S.; Guo, Ten-Huei

    2013-01-01

    A method of investigating the effects of high angle of attack (AOA) flight on turbofan engine performance is presented. The methodology involves combining a suite of diverse simulation tools. Three-dimensional, steady-state computational fluid dynamics (CFD) software is used to model the change in performance of a commercial aircraft-type inlet and fan geometry due to various levels of AOA. Parallel compressor theory is then applied to assimilate the CFD data with a zero-dimensional, nonlinear, dynamic turbofan engine model. The combined model shows that high AOA operation degrades fan performance and, thus, negatively impacts compressor stability margins and engine thrust. In addition, the engine response to high AOA conditions is shown to be highly dependent upon the type of control system employed.

  8. Technologies for Turbofan Noise Reduction

    NASA Technical Reports Server (NTRS)

    Huff, Dennis

    2005-01-01

    An overview presentation of NASA's engine noise research since 1992 is given for subsonic commercial aircraft applications. Highlights are included from the Advanced Subsonic Technology (AST) Noise Reduction Program and the Quiet Aircraft Technology (QAT) project with emphasis on engine source noise reduction. Noise reduction goals for 10 EPNdB by 207 and 20 EPNdB by 2022 are reviewed. Fan and jet noise technologies are highlighted from the AST program including higher bypass ratio propulsion, scarf inlets, forward-swept fans, swept/leaned stators, chevron nozzles, noise prediction methods, and active noise control for fans. Source diagnostic tests for fans and jets that have been completed over the past few years are presented showing how new flow measurement methods such as Particle Image Velocimetry (PIV) have played a key role in understanding turbulence, the noise generation process, and how to improve noise prediction methods. Tests focused on source decomposition have helped identify which engine components need further noise reduction. The role of Computational AeroAcoustics (CAA) for fan noise prediction is presented. Advanced noise reduction methods such as Hershel-Quincke tubes and trailing edge blowing for fan noise that are currently being pursued n the QAT program are also presented. Highlights are shown form engine validation and flight demonstrations that were done in the late 1990's with Pratt & Whitney on their PW4098 engine and Honeywell on their TFE-731-60 engine. Finally, future propulsion configurations currently being studied that show promise towards meeting NASA's long term goal of 20 dB noise reduction are shown including a Dual Fan Engine concept on a Blended Wing Body aircraft.

  9. Does a "continuous care model" affect the quality of life of patients undergoing coronary artery bypass grafting?

    PubMed

    Razmjoee, Nasrin; Ebadi, Abbas; Asadi-Lari, Mohsen; Hosseini, Marziyeh

    2017-03-01

    The physical and mental needs of patients with coronary heart disease are affected by both the disease and the heart surgery in different ways. Such diverse needs require different approaches. A continuous care model, which involves orientation, sensitization, control, and evaluation, may favorably influence patient outcomes following coronary artery bypass grafting (CABG). We were interested to ascertain whether a continuous care model might lead to improved quality of life, compared with a routine care model, in patients undergoing CABG. A total of 66 patients scheduled for CABG were identified and randomized to receive either continuous care (based on the continuous care model) or routine postoperative management for 2 months. The subjects' quality of life and its physical and mental dimensions were measured by the 12-item Short-Form Health Survey. Each dimension was scored between 0 and 100, and higher scores indicated better quality of life. One and 2 months after the intervention, the scores of quality of life and its two dimensions were significantly higher in the intervention group than in the control group (P < .001). The application of the continuous care model can promote health-related quality of life in patients after CABG.

  10. Euler analysis of turbofan/superfan integration for a transport aircraft

    NASA Astrophysics Data System (ADS)

    Naik, D. A.; Chen, H. C.; Su, T. Y.; Kao, T. J.

    1992-09-01

    A three-dimensional general multi-block Euler solver (GMBE) has been developed to analyze the propulsion integration effects of turbofan/superfan installations. Either flow-through or powered nacelles can be modelled. The code is demonstrated on a generic NASA low wing transport model with an advanced turbofan flow-through nacelle. The results compare favorably with experimental data obtained in the NASA Langley 16-Foot (4.88 m) Transonic Tunnel. The computed pressure distributions are used to identify, in terms of pressure coefficient peaks (maximum negative values) and gradients, undesirable flow regions in the vicinity of the pylon and nacelle. The results suggest that a change in toe angle and pylon trailing edge closure geometry will improve the propulsion integration.

  11. Development of a Turbofan Engine Simulation in a Graphical Simulation Environment

    NASA Technical Reports Server (NTRS)

    Parker, Khary I.; Guo, Ten-Heui

    2003-01-01

    This paper presents the development of a generic component level model of a turbofan engine simulation with a digital controller, in an advanced graphical simulation environment. The goal of this effort is to develop and demonstrate a flexible simulation platform for future research in propulsion system control and diagnostic technology. A previously validated FORTRAN-based model of a modern, high-performance, military-type turbofan engine is being used to validate the platform development. The implementation process required the development of various innovative procedures, which are discussed in the paper. Open-loop and closed-loop comparisons are made between the two simulations. Future enhancements that are to be made to the modular engine simulation are summarized.

  12. Impact of Cardiopulmonary Bypass on Respiratory Mucociliary Function in an Experimental Porcine Model

    PubMed Central

    Sánchez-Véliz, Rodrigo; Carmona, Maria José; Otsuki, Denise Aya; Freitas, Claudia; Benício, Anderson; Negri, Elnara Marcia; Malbouisson, Luiz Marcelo

    2015-01-01

    Background The impact of cardiac surgery using cardiopulmonary bypass (CPB) on the respiratory mucociliary function is unknown. This study evaluated the effects of CPB and interruption of mechanical ventilation on the respiratory mucociliary system. Methods Twenty-two pigs were randomly assigned to the control (n = 10) or CPB group (n = 12). After the induction of anesthesia, a tracheostomy was performed, and tracheal tissue samples were excised (T0) from both groups. All animals underwent thoracotomy. In the CPB group, an aorto-bicaval CPB was installed and maintained for 90 minutes. During the CPB, mechanical ventilation was interrupted, and the tracheal tube was disconnected. A second tracheal tissue sample was obtained 180 minutes after the tracheostomy (T180). Mucus samples were collected from the trachea using a bronchoscope at T0, T90 and T180. Ciliary beat frequency (CBF) and in situ mucociliary transport (MCT) were studied in ex vivo tracheal epithelium. Mucus viscosity (MV) was assessed using a cone-plate viscometer. Qualitative tracheal histological analysis was performed at T180 tissue samples. Results CBF decreased in the CPB group (13.1 ± 1.9 Hz vs. 11.1 ± 2.1 Hz, p < 0.05) but not in the control group (13.1 ± 1 Hz vs. 13 ± 2.9 Hz). At T90, viscosity was increased in the CPB group compared to the control (p < 0.05). No significant differences were observed in in situ MCT. Tracheal histology in the CPB group showed areas of ciliated epithelium loss, submucosal edema and infiltration of inflammatory cells. Conclusion CPB acutely contributed to alterations in tracheal mucocilliary function. PMID:26288020

  13. 77 FR 74123 - Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co KG Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-13

    ... Rolls-Royce Deutschland Ltd & Co KG (RRD) models Tay 620-15 and Tay 650-15 turbofan engines. This... correct an unsafe condition for the specified products. The MCAI states: The Tay 650-15 and Tay 650-15/10... assemblies installed in Tay 650-15 and Tay 650-15/10 engines as well as in Tay 620-15 and Tay...

  14. Peripheral artery bypass - leg

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/007394.htm Peripheral artery bypass - leg To use the sharing features on this page, please enable JavaScript. Peripheral artery bypass is surgery to reroute the blood supply ...

  15. Evaluation of a Novel Laser-assisted Coronary Anastomotic Connector - the Trinity Clip - in a Porcine Off-pump Bypass Model

    PubMed Central

    Stecher, David; Bronkers, Glenn; Noest, Jappe O.T.; Tulleken, Cornelis A.F.; Hoefer, Imo E.; van Herwerden, Lex A.; Pasterkamp, Gerard; Buijsrogge, Marc P.

    2014-01-01

    To simplify and facilitate beating heart (i.e., off-pump), minimally invasive coronary artery bypass surgery, a new coronary anastomotic connector, the Trinity Clip, is developed based on the excimer laser-assisted nonocclusive anastomosis technique. The Trinity Clip connector enables simplified, sutureless, and nonocclusive connection of the graft to the coronary artery, and an excimer laser catheter laser-punches the opening of the anastomosis. Consequently, owing to the complete nonocclusive anastomosis construction, coronary conditioning (i.e., occluding or shunting) is not necessary, in contrast to the conventional anastomotic technique, hence simplifying the off-pump bypass procedure. Prior to clinical application in coronary artery bypass grafting, the safety and quality of this novel connector will be evaluated in a long-term experimental porcine off-pump coronary artery bypass (OPCAB) study. In this paper, we describe how to evaluate the coronary anastomosis in the porcine OPCAB model using various techniques to assess its quality. Representative results are summarized and visually demonstrated. PMID:25490000

  16. A genetically engineered human Kunitz protease inhibitor with increased kallikrein inhibition in an ovine model of cardiopulmonary bypass.

    PubMed

    Ohri, S K; Parratt, R; White, T; Becket, J; Brannan, J J; Hunt, B J; Taylor, K M

    2001-05-01

    A recombinant human serine protease inhibitor known as Kunitz protease inhibitor (KPI) wild type has functional similarities to the bovine Kunitz inhibitor, aprotinin, and had shown a potential to reduce bleeding in an ovine model of cardiopulmonary bypass (CPB). The aim of this study was to assess KPI-185, a modification of KPI-wild type that differs from KPI-wild type in two amino acid residues and which enhances anti-kallikrein activity in a further double-blind, randomized study in an ovine model of CPB, and to compare with our previous study of KPI-wild type and aprotinin in the same ovine model. Post-operative drain losses and subjective assessment of wound 'dryness' showed no significant differences between KPI-185 and KPI-wild type, despite the significant enhancement of kallikrein inhibition using KPI-185 seen in serial kallikrein inhibition assays. These preliminary findings support the hypothesis that kallikrein inhibition is not the major mechanism by which Kunitz inhibitors such as aprotinin reduce perioperative bleeding.

  17. Development and verification of a mouse model for Roux-en-Y gastric bypass surgery with a small gastric pouch.

    PubMed

    Hao, Zheng; Zhao, Zhiyun; Berthoud, Hans-Rudolf; Ye, Jianping

    2013-01-01

    Existing mouse models of Roux-en-Y gastric bypass (RYGB) surgery are not comparable to human RYGB in gastric pouch volume for a large or absent gastric volume. The aim of this study was to develop and characterize a mouse RYGB model that closely replicates gastric pouch size of human RYGB surgery of about 5% of total gastric volume. We established this model in diet-induced obese (DIO) mice of C57BL/6J. This surgery resulted in a sustained 30% weight loss, entirely accounted for by decreased fat mass but not lean mass, compared to sham-operated mice on the high fat diet. Compared to sham-operated mice, energy expenditure corrected for total body weight was significantly increased by about 25%, and substrate utilization was shifted toward higher carbohydrate utilization at 8 weeks after RYGB when body weight had stabilized at the lower level. The energy expenditure persisted and carbohydrate utilization was even more pronounced when the mice were fed chow diet. Although significantly increased during daytime, overall locomotor activity was not significantly different. In response to cold exposure, RYGB mice exhibited an improved capacity to maintain the body temperature. In insulin tolerance test, exogenous insulin-induced suppression of plasma glucose levels was significantly greater in RYGB mice at 4 weeks after surgery. Paradoxically, food intake measured at 5 weeks after surgery was significantly increased, possibly in compensation for increased fecal energy loss and energy expenditure. In conclusion, this new model is a viable alternative to existing murine RYGB models and the model matches human RYGB surgery in anatomy. This model will be useful for studying molecular mechanisms involved in the beneficial effects of RYGB on body weight and glucose homeostasis.

  18. Type 2 diabetes mellitus control and atherosclerosis prevention in a non-obese rat model using duodenal-jejunal bypass.

    PubMed

    Chen, Xuan; Huang, Zhen; Ran, Wenhua; Liao, Gang; Zha, Lang; Wang, Ziwei

    2014-09-01

    Type 2 diabetes mellitus (T2DM) is a prevalent disease worldwide and during its conventional treatment, vascular complications remain unavoidable. Roux-en-Y gastric bypass (GBP) is able to induce the remission of T2DM. However, studies of duodenal-jejunal bypass (DJB), a modified procedure of GBP, are being carried out to investigate its ability to induce the remission of T2DM and protect the aorta from atherosclerosis. The present study aimed to investigate the effect of DJB on the rate of T2DM remission and the prevention of atherosclerosis in the aorta in rats with streptozotocin-induced diabetes without obesity, and to explore the mechanism of DJB in protecting the aorta from atherosclerosis. A T2DM rat model was established with a high-fat diet and low-dose streptozotocin. Surgery was performed to analyze its effects on glucose homeostasis, lipid metabolism, inflammation and pathological changes. Furthermore, changes in c-jun NH2-terminal kinase 1 (JNK1) and inhibitor of κB kinase (IKKβ) genes in the aorta following DJB surgery were examined. Levels of blood glucose, lipids, insulin and tumor necrosis factor (TNF)-α were significantly elevated in the T2DM diabetic model compared with the non-diabetic control. A gradual recovery was observed in the DJB group following surgery. Foam cells and atherosclerotic plaques appeared in the ascending aortic tissue in the sham-surgery and T2DM groups, whereas only slight lesions were observed in the DJB group. The expression levels of JNK1 and IKKβ genes in the aorta were significantly increased in the sham-operated and T2DM groups compared with those in the DJB and normal control groups. The present study demonstrated that DJB caused remission of T2DM without weight loss in non-obese rats. Thus, DJB may delay or prevent the occurrence and development of atherosclerosis in the aorta and this may occur through the JNK1 and nuclear factor κB (NF-κB) signaling pathways.

  19. Numerical investigation of haemodynamics in a helical-type artery bypass graft using non-Newtonian multiphase model.

    PubMed

    Wen, Jun; Liu, Kai; Khoshmanesh, Khashayar; Jiang, Wentao; Zheng, Tinghui

    2015-01-01

    The classic single-phase Newtonian blood flow model ignores the motion of red blood cells (RBCs) and their interaction with plasma. To address these issues, we adopted a multiphase non-Newtonian model to carry out a comparative study between a helical artery bypass graft (ABG) and a conventional ABG in which the blood flow is composed of plasma and RBCs. The investigation focused on the mechanism of RBC buildup in an ABG but the haemodynamic parameters obtained by single-phase and multiphase models were also compared. The aggregation of RBCs along the inside wall of a conventional ABG and at the heel of its distal anastomosis was predicted while a poor aggregation was observed along the helical ABG. In addition, RBCs were observed to gradually sediment along the gravity direction. However, the computed haemodynamic parameters by multiphase model qualitatively agreed well with those by single-phase model. It was concluded that (1) the single-phase computational fluid dynamics (CFD) is reasonable to do the computation of haemodynamic parameters in ABGs; (2) secondary flow does not definitely produce buildup of RBCs in the inside curvature, its configuration played an important role in the movement of RBCs and the dominating one-way rotating flow in a helical ABG guaranteed no buildup of RBCs on its inside wall and (3) gravity direction is important for the movement of RBCs which may help to explain why doing exercise is good for human health. This study helps to shed light on the migration of RBCs in ABGs, which cannot be explored by single-phase CFD models, and provides more understanding of the underlying flow mechanism for ABG failure.

  20. Canadian Forces Experience with Turbofan HCF - Case Study

    DTIC Science & Technology

    2005-10-01

    Canadian Forces Experience with Turbofan HCF – Case Study Corey Kinart, P. Eng. Magellan Aerospace Corporation 3160 Derry Road East Mississauga...Ontario Canada , L4T 1A9 ckinart@orenda.com Maj. Pierre Theriault National Defence Headquarters 101 Colonel By Drive Ottawa, Ontario Canada ...K1A 0K2 theriault.pg@forces.gc.ca SUMMARY High Cycle Fatigue (HCF) cracking of a Canadian Forces (CF) turbofan engine fuel tube resulted in a six

  1. 76 FR 72348 - Airworthiness Directives; Pratt & Whitney Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-23

    ... Directives; Pratt & Whitney Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION... Pratt & Whitney JT9D-7R4D, -7R4D1, -7R4E, -7R4E1, -7R4G2, -7R4H1, and - 7R4E4 turbofan engines. This..., P/N 735907, is necessary. We are proposing this AD to prevent critical life-limited rotating...

  2. Poor Sleep Quality in Patients after Coronary Artery Bypass Graft Surgery: An Intervention Study Using the PRECEDE-PROCEED Model

    PubMed Central

    Ranjbaran, Soheila; Dehdari, Tahereh; Sadeghniiat-Haghighi, Khosro; Majdabadi, Mahmood Mahmoodi

    2015-01-01

    Abstract Background: Poor sleep quality (SQ) is common among patients after coronary artery bypass graft surgery (CABG). This study attempted to determine the status of SQ following an intervention based on the PRECEDE-PROCEED model in patients with poor SQ after CABG. Methods: This study was a randomized clinical trial. The study sample, including 100 patients referred to the Cardiac Rehabilitation Clinic of Tehran Heart Center, was assigned either to the intervention (recipient of exercise and lifestyle training plus designed intervention based on the PRECEDE-PROCEED model) or to the control group (recipient of exercise and lifestyle training). Eight training sessions over 8 weeks were conducted for the intervention group. Predisposing, enabling, and reinforcing factors as well as social support and SQ were measured in the intervention group before and one month after the intervention and compared to those in the control group at the same time points. Results: The mean age of the patients in the intervention (24% women) and control (24% women) groups was 59.3 ± 7.3 and 59.5 ± 9.3 years, respectively. The results showed that the mean scores of SQ (p value < 0.001), knowledge (p value < 0.001), beliefs (p value < 0.001), sleep self-efficacy (p value < 0.001), enabling factors (p value < 0.001), reinforcing factors (p value < 0.001), and social support (p value < 0.001) were significantly different between the intervention and control groups after the intervention. Conclusion: Adding an intervention based on the PRECEDE-PROCEED model to the cardiac rehabilitation program may further improve the SQ of patients. PMID:26157457

  3. Noise-Reduction Benefits Analyzed for Over-the-Wing-Mounted Advanced Turbofan Engines

    NASA Technical Reports Server (NTRS)

    Berton, Jeffrey J.

    2000-01-01

    As we look to the future, increasingly stringent civilian aviation noise regulations will require the design and manufacture of extremely quiet commercial aircraft. Also, the large fan diameters of modern engines with increasingly higher bypass ratios pose significant packaging and aircraft installation challenges. One design approach that addresses both of these challenges is to mount the engines above the wing. In addition to allowing the performance trend towards large diameters and high bypass ratio cycles to continue, this approach allows the wing to shield much of the engine noise from people on the ground. The Propulsion Systems Analysis Office at the NASA Glenn Research Center at Lewis Field conducted independent analytical research to estimate the noise reduction potential of mounting advanced turbofan engines above the wing. Certification noise predictions were made for a notional long-haul commercial quadjet transport. A large quad was chosen because, even under current regulations, such aircraft sometimes experience difficulty in complying with certification noise requirements with a substantial margin. Also, because of its long wing chords, a large airplane would receive the greatest advantage of any noise-shielding benefit.

  4. Characterization and modeling of screen-printed metal insulator semiconductor tunnel junctions for integrated bypass functionality in crystalline silicon solar cells

    NASA Astrophysics Data System (ADS)

    Thaidigsmann, Benjamin; Lohmüller, Elmar; Fertig, Fabian; Clement, Florian; Wolf, Andreas

    2013-06-01

    This work investigates sintered, screen-printed silver contacts on lowly doped p-type silicon with different intermediate dielectric layer systems using scanning electron microscopy and dark current-voltage measurements. The data reveal electron tunneling through a thin insulating layer as the most probable transport mechanism. A model based on Fowler-Nordheim and direct tunneling is presented that allows for the description of reverse current-voltage characteristics and the extraction of effective contact properties. The investigated screen-printed metal insulator semiconductor structures are proposed as solar cell integrated bypass that reduces the risk of hot spot generation and power loss during partial shading of a module. Furthermore, the integrated bypass approach enables the fabrication of solar cells from silicon material that tends to show early breakdown of the p-n-junction.

  5. 75 FR 55459 - Airworthiness Directives; Pratt & Whitney (PW) PW4000 Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-13

    ...) PW4000 Series Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule... amend 14 CFR part 39 with a proposed AD. The proposed AD applies to PW PW4000 series turbofan...

  6. The impact of Roux-en-Y gastric bypass surgery on normal metabolism in a porcine model

    PubMed Central

    Lindqvist, Andreas; Ekelund, Mikael; Garcia-Vaz, Eliana; Ståhlman, Marcus; Pierzynowski, Stefan; Gomez, Maria F.; Rehfeld, Jens F.; Groop, Leif; Hedenbro, Jan

    2017-01-01

    Background A growing body of literature on Roux-en-Y gastric bypass surgery (RYGB) has generated inconclusive results on the mechanism underlying the beneficial effects on weight loss and glycaemia, partially due to the problems of designing clinical studies with the appropriate controls. Moreover, RYGB is only performed in obese individuals, in whom metabolism is perturbed and not completely understood. Methods In an attempt to isolate the effects of RYGB and its effects on normal metabolism, we investigated the effect of RYGB in lean pigs, using sham-operated pair-fed pigs as controls. Two weeks post-surgery, pigs were subjected to an intravenous glucose tolerance test (IVGTT) and circulating metabolites, hormones and lipids measured. Bile acid composition was profiled after extraction from blood, faeces and the gallbladder. Results A similar weight development in both groups of pigs validated our experimental model. Despite similar changes in fasting insulin, RYGB-pigs had lower fasting glucose levels. During an IVGTT RYGB-pigs had higher insulin and lower glucose levels. VLDL and IDL were lower in RYGB- than in sham-pigs. RYGB-pigs had increased levels of most amino acids, including branched-chain amino acids, but these were more efficiently suppressed by glucose. Levels of bile acids in the gallbladder were higher, whereas plasma and faecal bile acid levels were lower in RYGB- than in sham-pigs. Conclusion In a lean model RYGB caused lower plasma lipid and bile acid levels, which were compensated for by increased plasma amino acids, suggesting a switch from lipid to protein metabolism during fasting in the immediate postoperative period. PMID:28257455

  7. Comparison of advanced turboprop and turbofan airplanes

    NASA Technical Reports Server (NTRS)

    Johnson, V. S.

    1983-01-01

    Results of a parametric study to determine the effects of design variables and penalties on the fuel efficiency of Mach 0.8, 125-passenger, advanced turboprop airplanes show that propeller-wing interference penalty has a major effect. Propeller tip speed has a minor effect, and could be decreased to alleviate the noise problem without significant effects on fuel efficiency. The anticipated noise levels produced by the propfan will require additional acoustical treatment for the fuselage; this additional weight can have a significant effect on fuel efficiency. The propfan advantage over an equivalent technology turbofan is strongly dependent on the interference penalty and acoustical treatment weight. Lowering the cruise Mach number to around 0.73 would result in greatly increased fuel efficiency.

  8. Bird Ingestion into Large Turbofan Engines

    DTIC Science & Technology

    1992-05-01

    292 04/06/90 B767 CF6 80C2 SEMB FOR LD 268 05/ 23 /90 A320 CFM56 5 SEMB FOR TR 247 05/31/90 A300 JT9D 59A INVOLUNTARY POWER LOSS FOR TR 273 06/14/90 A320...OR MORE 1 0 0 1 6 TO 17 0 2 .0 2 4 TO 5 1 0 0 1 UNKNOWN 7 44 4 55 TOTALS 38 347 12 397 23 TABLE 4.2. BIRD SPECIES SPECIES MODAL WEIGHT MULTIPLE SPECIES...Gov.ernm.nt Accistton No, 3, Rec.p.ent’s Catalog No. DOT/FAA/CT-91/1 7 4. Title and Subtitle 5 . Report fote May 1992 BIRD INGESTION INTO LARGE TURBOFAN

  9. Fan rotor blades of turbofan engines

    SciTech Connect

    Zipps, R.H.; Rynaski, C.H.; Fulton, G.B.

    1986-11-11

    This patent describes a fan blade of the type extending outwardly from a rotor disk across the annular flowpath for working medium gases in the fan section of a turbofan engine, including: an airfoil section having an arcuate cross section contour at the inner wall of the working medium flowpath; and a root section having an upstream end and a downstream end wherein the root section is formed to an arcuate contour which approximates the arcuate contour of the airfoil cross section at the inner wall of the working medium flowpath projected onto the root section, and wherein the root section is convergently tapered from the downstream end toward the upstream end of the blade.

  10. Tests and analysis of a vented D thrust deflecting nozzle on a turbofan engine. [conducted at the outdoor aerodynamic research facility of the Ames Research Center

    NASA Technical Reports Server (NTRS)

    Roseberg, E. W.

    1982-01-01

    The objectives were to: obtain nozzle performance characteristics in and out of ground effects; demonstrate the compatibility of the nozzle with a turbofan engine; obtain pressure and temperature distributions on the surface of the D vented nozzle; and establish a correlation of the nozzle performance between small scale and large scale models. The test nozzle was a boilerplate model of the MCAIR D vented nozzle configured for operation with a General Electric YTF-34-F5 turbofan engine. The nozzle was configured to provide: a thrust vectoring range of 0 to 115 deg; a yaw vectoring range of 0 to 10 deg; variable nozzle area control; and variable spacing between the core exit and nozzle entrance station. Compatibility between the YTF-34-T5 turbofan engine and the D vented nozzle was demonstrated. Velocity coefficients of 0.96 and greater were obtained for 90 deg of thrust vectoring. The nozzle walls remained cool during all test conditions.

  11. Ice crystal ingestion by turbofans

    NASA Astrophysics Data System (ADS)

    Rios Pabon, Manuel A.

    This Thesis will present the problem of inflight icing in general and inflight icing caused by the ingestion of high altitude ice crystals produced by high energy mesoscale convective complexes in particular, and propose a new device to prevent it based on dielectric barrier discharge plasma. Inflight icing is known to be the cause of 583 air accidents and more than 800 deaths in more than a decade. The new ice crystal ingestion problem has caused more than 100 flights to lose engine power since the 1990's, and the NTSB identified it as one of the causes of the Air France flight 447 accident in 1-Jun2008. The mechanics of inflight icing not caused by ice crystals are well established. Aircraft surfaces exposed to supercooled liquid water droplets will accrete ice in direct proportion of the droplet catch and the freezing heat transfer process. The multiphase flow droplet catch is predicted by the simple sum of forces on each spherical droplet and a droplet trajectory calculation based on Lagrangian or Eulerian analysis. The most widely used freezing heat transfer model for inflight icing caused by supercooled droplets was established by Messinger. Several computer programs implement these analytical models to predict inflight icing, with LEWICE being based on Lagrangian analysis and FENSAP being based on Eulerian analysis as the best representatives among them. This Thesis presents the multiphase fluid mechanics particular to ice crystals, and explains how it differs from the established droplet multiphase flow, and the obstacles in implementing the former in computational analysis. A new modification of the Messinger thermal model is proposed to account for ice accretion produced by ice crystal impingement. Because there exist no computational and experimental ways to fully replicate ice crystal inflight icing, and because existing ice protections systems consume vast amounts of energy, a new ice protection device based on dielectric barrier discharge plasma is

  12. Turbofan aft duct suppressor study

    NASA Technical Reports Server (NTRS)

    Syed, A. A.; Motsinger, R. E.; Fiske, G. H.; Joshi, M. C.; Kraft, R. E.

    1983-01-01

    Suppressions due to acoustic treatment in the annular exhaust duct of a model fan were theoretically predicted and compared with measured suppressions. The predictions are based on the modal analysis of sound propagation in a straight annular flow duct with segmented treatment. Modal distributions of the fan noise source (fan-stator interaction only) were measured using in-duct modal probes. The flow profiles were also measured in the vicinity of the modal probes. The acoustic impedance of the single degree of freedom treatment was measured in the presence of grazing flow. The measured values of mode distribution of the fan noise source, the flow velocity profile and the acoustic impedance of the treatment in the duct were used as input to the prediction program. The predicted suppressions, under the assumption of uniform flow in the duct, compared well with the suppressions measured in the duct for all test conditions. The interaction modes generated by the rotor-stator interaction spanned a cut-off ratio range from nearly 1 to 7.

  13. Investigation of risks for cerebral embolism associated with the hemodynamics of cardiopulmonary bypass cannula: a numerical model.

    PubMed

    Avrahami, Idit; Dilmoney, Benny; Azuri, Aliza; Brand, Moshe; Cohen, Oved; Shani, Liran; Nir, Rony-Reuven; Bolotin, Gil

    2013-10-01

    Cerebral emboli originating in the ascending aorta are a major cause of noncardiac complications following cardiac surgery. The hemodynamics of the aortic cannula has been proven to play a significant role in emboli generation and distribution. The aim of the current study was to perform a thorough numerical investigation in order to examine the effect of the design and orientation of the cannula used during cardiopulmonary bypass on the risk to develop cerebral embolism. Hemodynamic analyses compared numerical models of 27 cases consisting of six different cannula orientations, four aortic anatomies, and three cannula designs. The cannula designs included a straight-tip (ST) cannula, a moderately curved tip cannula (TIP1 ), and a sharp-angle curved cannula (TIP2 ). Outcome measures included hemodynamic parameters such as emanating jet velocity, jet velocity drop, maximal shear stress, aortic wall reaction, emboli pathlines and distribution between upper and lower vessels, and stagnation regions. Based on these parameters, the risks for hemolysis, atheroembolism, and cerebral embolism were evaluated and compared. On one hand, the jet emerging from the ST cannula generated large wall-shear stress at the aortic wall; this may have triggered the erosion and distribution of embolic atheromatous debris from the aortic arch. On the other hand, it diverted more emboli from the clamp region to the descending aorta and thus reduced the risk for cerebral embolism. The TIP1 cannula demonstrated less shear stress on the aortic wall and diverted more emboli from the clamp region toward the upper vessels. The TIP2 cannula exhibited a stronger emanating jet, higher shear stress inside the cannula, and highly disturbed flow, which was more stagnant near the clamp region. Current findings support the significant impact of the cannula design and orientation on emboli generation and distribution. Specifically, the straight tip cannula demonstrated a reduced risk of cerebral embolism

  14. The Impact of Peplau's Therapeutic Communication Model on Anxiety and Depression in Patients Candidate for Coronary Artery Bypass

    PubMed Central

    Zarea, Kourosh; Maghsoudi, Solmaz; Dashtebozorgi, Bahman; Hghighizadeh, Mohammad Hossin; Javadi, Mostafa

    2014-01-01

    Background and Objective: Anxiety and depression are among the psychological disorders in heart surgeries. Establishing a simple communication is essential to reduce anxiety and depression. Hence, the objective of the present studywas to examine the impact of Peplau therapeutic communication model on anxiety and depression in patients, who were candidate for coronary artery bypass in Al-Zahra Heart Hospital, Shiraz during 2012-2013. Methods: This is a clinical trial in which 74 patients were randomly divided into intervention and control groups, each consisted of 37 patients. Anxiety and depression levels were assessed before, and two and four months after intervention using the Hospital Anxiety and Depression Scale (HADS). Seven therapeutic communication sessions were held in four stages. Data were analyzed with the SPSS (version 16) using analysis of covariance. Results: The mean anxiety and depression levels decreased in the intervention group after the therapeutic communication (p<0.01). Anxiety scores in the intervention group before and after intervention were 10.23 and 9.38, respectively. While the corresponding scores in the control group were 10.26 and 11.62, respectively. Depression scores in the intervention group before and after intervention were 11 and 9.13, respectively. The corresponding scores in the control group were 11.30 and 12.08, respectively. Conclusion: The results demonstrated the positive role of therapeutic communication in reducing anxiety and depression of the patients. Therefore, the therapeutic communication is recommended as a simple, cost effective and efficient method in this area. PMID:25505931

  15. 78 FR 48339 - Airworthiness Directives; Rolls-Royce Corporation Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-08

    ... Corporation Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed... to certain Rolls-Royce Corporation (RRC) AE 3007A series turbofan engines. The existing AD currently..., and reduces their approved life limits. This proposed AD would clarify the AE 3007A turbofan...

  16. 14 CFR 23.934 - Turbojet and turbofan engine thrust reverser systems tests.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Turbojet and turbofan engine thrust... CATEGORY AIRPLANES Powerplant General § 23.934 Turbojet and turbofan engine thrust reverser systems tests. Thrust reverser systems of turbojet or turbofan engines must meet the requirements of § 33.97 of...

  17. 14 CFR 23.934 - Turbojet and turbofan engine thrust reverser systems tests.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Turbojet and turbofan engine thrust... CATEGORY AIRPLANES Powerplant General § 23.934 Turbojet and turbofan engine thrust reverser systems tests. Thrust reverser systems of turbojet or turbofan engines must meet the requirements of § 33.97 of...

  18. 14 CFR 23.934 - Turbojet and turbofan engine thrust reverser systems tests.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Turbojet and turbofan engine thrust... CATEGORY AIRPLANES Powerplant General § 23.934 Turbojet and turbofan engine thrust reverser systems tests. Thrust reverser systems of turbojet or turbofan engines must meet the requirements of § 33.97 of...

  19. 14 CFR 23.934 - Turbojet and turbofan engine thrust reverser systems tests.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Turbojet and turbofan engine thrust... CATEGORY AIRPLANES Powerplant General § 23.934 Turbojet and turbofan engine thrust reverser systems tests. Thrust reverser systems of turbojet or turbofan engines must meet the requirements of § 33.97 of...

  20. 14 CFR 23.934 - Turbojet and turbofan engine thrust reverser systems tests.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Turbojet and turbofan engine thrust... CATEGORY AIRPLANES Powerplant General § 23.934 Turbojet and turbofan engine thrust reverser systems tests. Thrust reverser systems of turbojet or turbofan engines must meet the requirements of § 33.97 of...

  1. Effect of Accessory Power Take-off Variation on a Turbofan Engine Performance

    DTIC Science & Technology

    2012-09-26

    EFFECT OF ACCESSORY POWER TAKE-OFF VARIATION ON A TURBOFAN ENGINE PERFORMANCE THESIS...ACCESSORY POWER TAKE-OFF VARIATIONS ON A TURBOFAN ENGINE PERFORMANCE DISSERTATION Presented to the Faculty Department of Aeronautics and...TURBOFAN ENGINE PERFORMANCE Anis Faidi, BS 1st Lieutenant, TUNAF Approved

  2. Robust fault detection of turbofan engines subject to adaptive controllers via a Total Measurable Fault Information Residual (ToMFIR) technique.

    PubMed

    Chen, Wen; Chowdhury, Fahmida N; Djuric, Ana; Yeh, Chih-Ping

    2014-09-01

    This paper provides a new design of robust fault detection for turbofan engines with adaptive controllers. The critical issue is that the adaptive controllers can depress the faulty effects such that the actual system outputs remain the pre-specified values, making it difficult to detect faults/failures. To solve this problem, a Total Measurable Fault Information Residual (ToMFIR) technique with the aid of system transformation is adopted to detect faults in turbofan engines with adaptive controllers. This design is a ToMFIR-redundancy-based robust fault detection. The ToMFIR is first introduced and existing results are also summarized. The Detailed design process of the ToMFIRs is presented and a turbofan engine model is simulated to verify the effectiveness of the proposed ToMFIR-based fault-detection strategy.

  3. Heart bypass surgery

    MedlinePlus Videos and Cool Tools

    Heart bypass surgery begins with an incision made in the chest, with the breastbone cut exposing the heart. Next, a portion of the saphenous vein is ... used to bypass the blocked arteries in the heart. The venous graft is sewn to the aorta ...

  4. Results of an Advanced Fan Stage Operating Over a Wide Range of Speed and Bypass Ratio. Part 2; Comparison of CFD and Experimental Results

    NASA Technical Reports Server (NTRS)

    Celestina, Mark L.; Suder, Kenneth L.; Kulkarni, Sameer

    2010-01-01

    NASA and GE teamed to design and build a 57 percent engine scaled fan stage for a Mach 4 variable cycle turbofan/ramjet engine for access to space with multipoint operations. This fan stage was tested in NASA's transonic compressor facility. The objectives of this test were to assess the aerodynamic and aero mechanic performance and operability characteristics of the fan stage over the entire range of engine operation including: 1) sea level static take-off; 2) transition over large swings in fan bypass ratio; 3) transition from turbofan to ramjet; and 4) fan wind-milling operation at high Mach flight conditions. This paper will focus on an assessment of APNASA, a multistage turbomachinery analysis code developed by NASA, to predict the fan stage performance and operability over a wide range of speeds (37 to 100 percent) and bypass ratios.

  5. Digital integrated control of a Mach 2.5 mixed-compression supersonic inlet and an augmented mixed-flow turbofan engine

    NASA Technical Reports Server (NTRS)

    Batterton, P. G.; Arpasi, D. J.; Baumbick, R. J.

    1974-01-01

    A digitally implemented integrated inlet-engine control system was designed and tested on a mixed-compression, axisymmetric, Mach 2.5, supersonic inlet with 45 percent internal supersonic area contraction and a TF30-P-3 augmented turbofan engine. The control matched engine airflow to available inlet airflow. By monitoring inlet terminal shock position and over-board bypass door command, the control adjusted engine speed so that in steady state, the shock would be at the desired location and the overboard bypass doors would be closed. During engine-induced transients, such as augmentor light-off and cutoff, the inlet operating point was momentarily changed to a more supercritical point to minimize unstarts. The digital control also provided automatic inlet restart. A variable inlet throat bleed control, based on throat Mach number, provided additional inlet stability margin.

  6. Operating condition and geometry effects on low-frequency afterburner combustion instability in a turbofan at altitude

    NASA Technical Reports Server (NTRS)

    Cullom, R. R.; Johnsen, R. L.

    1979-01-01

    Three afterburner configurations were tested in a low-bypass-ratio turbofan engine to determine the effect of various fuel distributions, inlet conditions, flameholder geometry, and fuel injection location on combustion instability. Tests were conducted at simulated flight conditions of Mach 0.75 and 1.3 at altitudes from 11,580 to 14,020 m (38,000 to 46,000 ft). In these tests combustion instability with frequency from 28 to 90 Hz and peak-to-peak pressure amplitude up to 46.5 percent of the afterburner inlet total pressure level was encountered. Combustion instability was suppressed in these tests by varying the fuel distribution in the afterburner.

  7. Computer method for design of acoustic liners for turbofan engines

    NASA Technical Reports Server (NTRS)

    Minner, G. L.; Rice, E. J.

    1976-01-01

    A design package is presented for the specification of acoustic liners for turbofans. An estimate of the noise generation was made based on modifications of existing noise correlations, for which the inputs are basic fan aerodynamic design variables. The method does not predict multiple pure tones. A target attenuation spectrum was calculated which was the difference between the estimated generation spectrum and a flat annoyance-weighted goal attenuated spectrum. The target spectrum was combined with a knowledge of acoustic liner performance as a function of the liner design variables to specify the acoustic design. The liner design method at present is limited to annular duct configurations. The detailed structure of the liner was specified by combining the required impedance (which is a result of the previous step) with a mathematical model relating impedance to the detailed structure. The design procedure was developed for a liner constructed of perforated sheet placed over honeycomb backing cavities. A sample calculation was carried through in order to demonstrate the design procedure, and experimental results presented show good agreement with the calculated results of the method.

  8. Interactive Educational Tool for Turbofan and Afterburning Turbojet Engines

    NASA Technical Reports Server (NTRS)

    Benson, Thomas J.

    1997-01-01

    A workstation-based, interactive educational computer program has been developed at the NASA Lewis Research Center to aid in the teaching and understanding of turbine engine design and analysis. This tool has recently been extended to model the performance of two-spool turbofans and afterburning turbojets. The program solves for the flow conditions through the engine by using classical one-dimensional thermodynamic analysis found in various propulsion textbooks. Either an approximately thermally perfect or calorically perfect gas can be used in the thermodynamic analysis. Students can vary the design conditions through a graphical user interface; engine performance is calculated immediately. A variety of graphical formats are used to present results, including numerical results, moving bar charts, and student-generated temperature versus entropy (Ts), pressure versus specific volume (pv), and engine performance plots. The package includes user-controlled printed output, restart capability, online help screens, and a browser that displays teacher-prepared lessons in turbomachinery. The program runs on a variety of workstations or a personal computer using the UNIX operating system and X-based graphics. It is being tested at several universities in the midwestern United States; the source and executables are available free from the author.

  9. Computation of noise radiation from turbofans: A parametric study

    NASA Astrophysics Data System (ADS)

    Nallasamy, M.

    1995-07-01

    This report presents the results of a parametric study of the turbofan far-field noise radiation using a finite element technique. Several turbofan noise radiation characteristics of both the inlet and the aft ducts have been examined through the finite element solutions. The predicted far-field principal lobe angle variations with duct Mach number and cut-off ratio compare very well with the available analytical results. The solutions also show that the far-field lobe angle is only a function of cut-off ratio, and nearly independent of the mode number. These results indicate that the finite element codes are well suited for the prediction of noise radiation characteristics of a turbofan. The effects of variations in the aft duct geometry are examined. The ability of the codes to handle ducts with acoustic treatments is also demonstrated.

  10. Computation of noise radiation from turbofans: A parametric study

    NASA Technical Reports Server (NTRS)

    Nallasamy, M.

    1995-01-01

    This report presents the results of a parametric study of the turbofan far-field noise radiation using a finite element technique. Several turbofan noise radiation characteristics of both the inlet and the aft ducts have been examined through the finite element solutions. The predicted far-field principal lobe angle variations with duct Mach number and cut-off ratio compare very well with the available analytical results. The solutions also show that the far-field lobe angle is only a function of cut-off ratio, and nearly independent of the mode number. These results indicate that the finite element codes are well suited for the prediction of noise radiation characteristics of a turbofan. The effects of variations in the aft duct geometry are examined. The ability of the codes to handle ducts with acoustic treatments is also demonstrated.

  11. Application of the MNA design method to a nonlinear turbofan engine. [multivariable Nyquist array method

    NASA Technical Reports Server (NTRS)

    Leininger, G. G.

    1981-01-01

    Using nonlinear digital simulation as a representative model of the dynamic operation of the QCSEE turbofan engine, a feedback control system is designed by variable frequency design techniques. Transfer functions are generated for each of five power level settings covering the range of operation from approach power to full throttle (62.5% to 100% full power). These transfer functions are then used by an interactive control system design synthesis program to provide a closed loop feedback control using the multivariable Nyquist array and extensions to multivariable Bode diagrams and Nichols charts.

  12. Design and verification of a turbofan swirl augmentor

    NASA Technical Reports Server (NTRS)

    Egan, W. J., Jr.; Shadowen, J. H.

    1978-01-01

    The paper discusses the details of the design and verification testing of a full-scale turbofan 'swirl' augmentor at sea level and altitude. No flameholders are required in the swirl augmentor since the radial motion of the hot pilot gases and subsequent combustion products provides a continuous ignition front across the stream. Results of rig testing of this full-scale swirl augmentor on an F100 engine, which are very encouraging, and future development plans are presented. The results validate the application of the centrifugal-force swirling flow concept to a turbofan augmentor.

  13. 78 FR 24671 - Airworthiness Directives; General Electric Company Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-26

    ... Electric Company (GE) CF6-80C2 A1/A2/A3/A5/A8/A5F/B1/B2/B4/B5F/B6/B1F/B2F/B4F/B6F/B7F/D1F turbofan engines...-AD; Amendment 39-17438; AD 2013-08-20] RIN 2120-AA64 Airworthiness Directives; General Electric Company Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule....

  14. Gastric bypass surgery

    MedlinePlus

    ... your legs to help prevent blood clots from forming. You will receive shots of medicine to prevent ... diversion with duodenal switch Dumping syndrome References Buchwald H. Laparoscopic Roux-en-Y gastric bypass. In: Buchwald ...

  15. Seizures Following Cardiopulmonary Bypass

    PubMed Central

    Brouwer, Monique E.; McMeniman, William J.

    2016-01-01

    Abstract: Seizures following cardiopulmonary bypass are an immediate and alarming indication that a neurologic event has occurred. A case report of a 67-year-old man undergoing aortic valve surgery who unexpectedly experiences seizures following cardiopulmonary bypass is outlined. Possible contributing factors including atheromatous disease in the aorta, low cerebral perfusion pressures, an open-chamber procedure, and the use of tranexamic acid are identified. PMID:27729707

  16. Ice Particle Transport Analysis With Phase Change for the E(sup 3) Turbofan Engine Using LEWICE3D Version 3.2

    NASA Technical Reports Server (NTRS)

    Bidwell, Colin, S.

    2012-01-01

    Ice Particle trajectory calculations with phase change were made for the Energy Efficient Engine (E(sup 3)) using the LEWICE3D Version 3.2 software. The particle trajectory computations were performed using the new Glenn Ice Particle Phase Change Model which has been incorporated into the LEWICE3D Version 3.2 software. The E(sup 3) was developed by NASA and GE in the early 1980 s as a technology demonstrator and is representative of a modern high bypass turbofan engine. The E(sup 3) flow field was calculated using the NASA Glenn ADPAC turbomachinery flow solver. Computations were performed for the low pressure compressor of the E(sup 3) for a Mach 0.8 cruise condition at 11,887 m assuming a standard warm day for ice particle sizes of 5, 20, and 100 microns and a free stream particle concentration of 0.3 g/cu m. The impingement efficiency results showed that as particle size increased average impingement efficiencies and scoop factors increased for the various components. The particle analysis also showed that the amount of mass entering the inner core decreased with increased particle size because the larger particles were less able to negotiate the turn into the inner core due to particle inertia. The particle phase change analysis results showed that the larger particles warmed less as they were transported through the low pressure compressor. Only the smallest 5 micron particles were warmed enough to produce melting and the amount of melting was relatively small with a maximum average melting fraction of 0.836. The results also showed an appreciable amount of particle sublimation and evaporation for the 5 micron particles entering the engine core (22 percent).

  17. Off-Design Analysis of a High Bypass Turbofan Using a Pulsed Detonation Combustor

    DTIC Science & Technology

    2010-03-01

    the Chapman - Jouguet Mach number with a total energy correction applied. Results indicate that fill fraction can be adjusted to reduce the TSFC to... Chapman - Jouguet Theory ............................................................................................8 Zeldovich-von Nuemann-Doring Theory...function (lbf) ltube Tube length (in) MCJ Chapman - Jouguet Mach number xiv Symbol Mvalve Valve Mach number

  18. Analytical evaluation of the impact of broad specification fuels on high bypass turbofan engine combustors

    NASA Technical Reports Server (NTRS)

    Lohmann, R. P.; Szetela, E. J.; Vranos, A.

    1978-01-01

    The impact of the use of broad specification fuels on the design, performance durability, emissions and operational characteristics of combustors for commercial aircraft gas turbine engines was assessed. Single stage, vorbix and lean premixed prevaporized combustors, in the JT9D and an advanced energy efficient engine cycle were evaluated when operating on Jet A and ERBS (Experimental Referee Broad Specification) fuels. Design modifications, based on criteria evolved from a literature survey, were introduced and their effectiveness at offsetting projected deficiencies resulting from the use of ERBS was estimated. The results indicate that the use of a broad specification fuel such as ERBS, will necessitate significant technology improvements and redesign if deteriorated performance, durability and emissions are to be avoided. Higher radiant heat loads are projected to seriously compromise liner life while the reduced thermal stability of ERBS will require revisions to the engine-airframe fuel system to reduce the thermal stress on the fuel. Smoke and emissions output are projected to increase with the use of broad specification fuels. While the basic geometry of the single stage and vorbix combustors are compatible with the use of ERBS, extensive redesign of the front end of the lean premixed prevaporized burner will be required to achieve satisfactory operation and optimum emissions.

  19. Comparative Analysis of a High Bypass Turbofan Using a Pulsed Detonation Combustor

    DTIC Science & Technology

    2007-03-01

    Thrust Specific Fuel Consumption . . . . . . . . . . . . . 67 xiii List of Abbreviations Abbreviation Page PDE Pulsed Detonation Engine...past ten years to develop pulsed det- onation engines ( PDE ) as a means of aircraft propulsion. Detonation combustion holds the promise of a more...aviation engine, and detonation creates more of it than previous aircraft engines. It is hoped that a marriage of the PDE with traditional

  20. 76 FR 77108 - Airworthiness Directives; International Aero Engines Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-12

    ... Engines Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: We are adopting a new airworthiness directive (AD) for International Aero Engines (IAE) V2500-A1... engines. This AD was prompted by three reports of high- pressure turbine (HPT) case burn-through...

  1. 77 FR 1043 - Airworthiness Directives; Honeywell International Inc. Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-09

    ... International Inc. Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of... engines. DATES: We must receive comments on this proposed AD by March 9, 2012. ADDRESSES: You may send... referenced service information at the FAA, Engine & Propeller Directorate, 12 New England Executive...

  2. 77 FR 9868 - Airworthiness Directives; Honeywell International Inc. Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-21

    ... turbofan engines. This proposed AD was prompted by a report of a rim/web separation of a first stage low... uncontained disk separation, leading to fuel tank penetration, fire, personal injury, and damage to the... receive about this proposed AD. Discussion We received a report of a rim/web separation on an LPT1...

  3. 78 FR 47534 - Airworthiness Directives; General Electric Company Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-06

    ... prohibition as AD 2013-14-51 and also prohibits operation of any airplane 60 days after the effective date of... Federal Aviation Administration 14 CFR Part 39 [Docket No. FAA-2013-0447; Directorate Identifier 2013-NE... Company Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule;...

  4. 78 FR 5710 - Airworthiness Directives; Engine Alliance Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-28

    ... GP7277 turbofan engines. This AD requires initial and repetitive borescope inspections and removal from service before further flight if one or more burn holes are detected, in certain high-pressure turbine (HPT) stage 2 nozzles. This AD also requires mandatory removal from service of these HPT stage...

  5. 77 FR 74125 - Airworthiness Directives; General Electric Company Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-13

    ... Federal Aviation Administration 14 CFR Part 39 RIN 2120-AA64 Airworthiness Directives; General Electric Company Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed rulemaking (NPRM). SUMMARY: We propose to adopt a new airworthiness directive (AD) for all General...

  6. 78 FR 72567 - Airworthiness Directives; General Electric Company Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-03

    ... Company Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: We are adopting a new airworthiness directive (AD) for certain General Electric Company (GE) GE90... Proposed AD The Boeing Company and FedEx Express agreed with the AD as proposed. Request To Change...

  7. The Promise and Challenges of Ultra High Bypass Ratio Engine Technology and Integration

    NASA Technical Reports Server (NTRS)

    Hughes, Chris

    2011-01-01

    In this presentation, an overview of the research being conducted by the ERA Project in Ultra High Bypass aircraft propulsion and in partnership with Pratt & Whitney with their Geared TurboFan (GTF) is given. The ERA goals are shown followed by a discussion of what areas need to be addressed on the engine to achieve the goals and how the GTF is uniquely qualified to meet the goals through a discussion of what benefits the cycle provides. The first generation GTF architecture is then shown highlighting the areas of collaboration with NASA, and the fuel burn, noise and emissions reductions possible based on initial static ground test and flight test data of the first GTF engine. Finally, a 5 year technology roadmap is presented focusing on Ultra High Bypass propulsion technology research areas that are being pursued and being planned by ERA and P&W under their GTF program.

  8. Dispersion, dissipation and refraction of shock waves in acoustically treated turbofan inlets

    NASA Astrophysics Data System (ADS)

    Prasad, Dilip; Li, Ding; A. Topol, David

    2015-09-01

    This paper describes a numerical investigation of the effects of the inlet duct liner on the acoustics of a high-bypass ratio turbofan rotor operating at supersonic tip relative flow conditions. The near field of the blade row is then composed of periodic shocks that evolve spatially both because of the varying mean flow and because of the presence of acoustic treatment. The evolution of this shock system is studied using a Computational Fluid Dynamics-based method incorporating a wall impedance boundary condition. The configuration examined is representative of a fan operating near the takeoff condition. The behavior of the acoustic power and the associated waveforms reveal that significant dispersion occurs to the extent that there are no shocks in the perturbation field leaving the entrance plane of the duct. The effect of wave refraction due to the high degree of shear in the mean flow near the entrance plane of the inlet is examined, and numerical experiments are conducted to show that the incorporation of liners in this region can be highly beneficial. The implications of these results for the design of aircraft engine acoustic liners are discussed.

  9. Refined Exploration of Turbofan Design Options for an Advanced Single-Aisle Transport

    NASA Technical Reports Server (NTRS)

    Guynn, Mark D.; Berton, Jeffrey J.; Fisher, Kenneth L.; Haller, William J.; Tong, Michael T.; Thurman, Douglas R.

    2011-01-01

    A comprehensive exploration of the turbofan engine design space for an advanced technology single-aisle transport (737/A320 class aircraft) was conducted previously by the authors and is documented in a prior report. Through the course of that study and in a subsequent evaluation of the approach and results, a number of enhancements to the engine design ground rules and assumptions were identified. A follow-on effort was initiated to investigate the impacts of these changes on the original study results. The fundamental conclusions of the prior study were found to still be valid with the revised engine designs. The most significant impact of the design changes was a reduction in the aircraft weight and block fuel penalties incurred with low fan pressure ratio, ultra-high bypass ratio designs. This enables lower noise levels to be pursued (through lower fan pressure ratio) with minor negative impacts on aircraft weight and fuel efficiency. Regardless of the engine design selected, the results of this study indicate the potential for the advanced aircraft to realize substantial improvements in fuel efficiency, emissions, and noise compared to the current vehicles in this size class.

  10. Near-field sound radiation of fan tones from an installed turbofan aero-engine.

    PubMed

    McAlpine, Alan; Gaffney, James; Kingan, Michael J

    2015-09-01

    The development of a distributed source model to predict fan tone noise levels of an installed turbofan aero-engine is reported. The key objective is to examine a canonical problem: how to predict the pressure field due to a distributed source located near an infinite, rigid cylinder. This canonical problem is a simple representation of an installed turbofan, where the distributed source is based on the pressure pattern generated by a spinning duct mode, and the rigid cylinder represents an aircraft fuselage. The radiation of fan tones can be modelled in terms of spinning modes. In this analysis, based on duct modes, theoretical expressions for the near-field acoustic pressures on the cylinder, or at the same locations without the cylinder, have been formulated. Simulations of the near-field acoustic pressures are compared against measurements obtained from a fan rig test. Also, the installation effect is quantified by calculating the difference in the sound pressure levels with and without the adjacent cylindrical fuselage. Results are shown for the blade passing frequency fan tone radiated at a supersonic fan operating condition.

  11. Constrained Kalman Filtering Via Density Function Truncation for Turbofan Engine Health Estimation

    NASA Technical Reports Server (NTRS)

    Simon, Dan; Simon, Donald L.

    2006-01-01

    Kalman filters are often used to estimate the state variables of a dynamic system. However, in the application of Kalman filters some known signal information is often either ignored or dealt with heuristically. For instance, state variable constraints (which may be based on physical considerations) are often neglected because they do not fit easily into the structure of the Kalman filter. This paper develops an analytic method of incorporating state variable inequality constraints in the Kalman filter. The resultant filter truncates the PDF (probability density function) of the Kalman filter estimate at the known constraints and then computes the constrained filter estimate as the mean of the truncated PDF. The incorporation of state variable constraints increases the computational effort of the filter but significantly improves its estimation accuracy. The improvement is demonstrated via simulation results obtained from a turbofan engine model. The turbofan engine model contains 3 state variables, 11 measurements, and 10 component health parameters. It is also shown that the truncated Kalman filter may be a more accurate way of incorporating inequality constraints than other constrained filters (e.g., the projection approach to constrained filtering).

  12. Separating Turbofan Engine Noise Sources Using Auto and Cross Spectra from Four Microphones

    NASA Technical Reports Server (NTRS)

    Miles, Jeffrey Hilton

    2008-01-01

    The study of core noise from turbofan engines has become more important as noise from other sources such as the fan and jet were reduced. A multiple-microphone and acoustic-source modeling method to separate correlated and uncorrelated sources is discussed. The auto- and cross spectra in the frequency range below 1000 Hz are fitted with a noise propagation model based on a source couplet consisting of a single incoherent monopole source with a single coherent monopole source or a source triplet consisting of a single incoherent monopole source with two coherent monopole point sources. Examples are presented using data from a Pratt& Whitney PW4098 turbofan engine. The method separates the low-frequency jet noise from the core noise at the nozzle exit. It is shown that at low power settings, the core noise is a major contributor to the noise. Even at higher power settings, it can be more important than jet noise. However, at low frequencies, uncorrelated broadband noise and jet noise become the important factors as the engine power setting is increased.

  13. Ultra-high speed vacuum pump system with first stage turbofan and second stage turbomolecular pump

    SciTech Connect

    Jostlein, Hans

    2006-04-04

    An ultra-high speed vacuum pump evacuation system includes a first stage ultra-high speed turbofan and a second stage conventional turbomolecular pump. The turbofan is either connected in series to a chamber to be evacuated, or is optionally disposed entirely within the chamber. The turbofan employs large diameter rotor blades operating at high linear blade velocity to impart an ultra-high pumping speed to a fluid. The second stage turbomolecular pump is fluidly connected downstream from the first stage turbofan. In operation, the first stage turbofan operates in a pre-existing vacuum, with the fluid asserting only small axial forces upon the rotor blades. The turbofan imparts a velocity to fluid particles towards an outlet at a high volume rate, but moderate compression ratio. The second stage conventional turbomolecular pump then compresses the fluid to pressures for evacuation by a roughing pump.

  14. Predicting reintubation, prolonged mechanical ventilation and death in post-coronary artery bypass graft surgery: a comparison between artificial neural networks and logistic regression models

    PubMed Central

    Mendes, Renata G.; de Souza, César R.; Machado, Maurício N.; Correa, Paulo R.; Di Thommazo-Luporini, Luciana; Arena, Ross; Myers, Jonathan; Pizzolato, Ednaldo B.

    2015-01-01

    Introduction In coronary artery bypass (CABG) surgery, the common complications are the need for reintubation, prolonged mechanical ventilation (PMV) and death. Thus, a reliable model for the prognostic evaluation of those particular outcomes is a worthwhile pursuit. The existence of such a system would lead to better resource planning, cost reductions and an increased ability to guide preventive strategies. The aim of this study was to compare different methods – logistic regression (LR) and artificial neural networks (ANNs) – in accomplishing this goal. Material and methods Subjects undergoing CABG (n = 1315) were divided into training (n = 1053) and validation (n = 262) groups. The set of independent variables consisted of age, gender, weight, height, body mass index, diabetes, creatinine level, cardiopulmonary bypass, presence of preserved ventricular function, moderate and severe ventricular dysfunction and total number of grafts. The PMV was also an input for the prediction of death. The ability of ANN to discriminate outcomes was assessed using receiver-operating characteristic (ROC) analysis and the results were compared using a multivariate LR. Results The ROC curve areas for LR and ANN models, respectively, were: for reintubation 0.62 (CI: 0.50–0.75) and 0.65 (CI: 0.53–0.77); for PMV 0.67 (CI: 0.57–0.78) and 0.72 (CI: 0.64–0.81); and for death 0.86 (CI: 0.79–0.93) and 0.85 (CI: 0.80–0.91). No differences were observed between models. Conclusions The ANN has similar discriminating power in predicting reintubation, PMV and death outcomes. Thus, both models may be applicable as a predictor for these outcomes in subjects undergoing CABG. PMID:26322087

  15. Load Sharing Behavior of Star Gearing Reducer for Geared Turbofan Engine

    NASA Astrophysics Data System (ADS)

    Mo, Shuai; Zhang, Yidu; Wu, Qiong; Wang, Feiming; Matsumura, Shigeki; Houjoh, Haruo

    2017-03-01

    Load sharing behavior is very important for power-split gearing system, star gearing reducer as a new type and special transmission system can be used in many industry fields. However, there is few literature regarding the key multiple-split load sharing issue in main gearbox used in new type geared turbofan engine. Further mechanism analysis are made on load sharing behavior among star gears of star gearing reducer for geared turbofan engine. Comprehensive meshing error analysis are conducted on eccentricity error, gear thickness error, base pitch error, assembly error, and bearing error of star gearing reducer respectively. Floating meshing error resulting from meshing clearance variation caused by the simultaneous floating of sun gear and annular gear are taken into account. A refined mathematical model for load sharing coefficient calculation is established in consideration of different meshing stiffness and supporting stiffness for components. The regular curves of load sharing coefficient under the influence of interactions, single action and single variation of various component errors are obtained. The accurate sensitivity of load sharing coefficient toward different errors is mastered. The load sharing coefficient of star gearing reducer is 1.033 and the maximum meshing force in gear tooth is about 3010 N. This paper provides scientific theory evidences for optimal parameter design and proper tolerance distribution in advanced development and manufacturing process, so as to achieve optimal effects in economy and technology.

  16. A Foreign Object Damage Event Detector Data Fusion System for Turbofan Engines

    NASA Technical Reports Server (NTRS)

    Turso, James A.; Litt, Jonathan S.

    2004-01-01

    A Data Fusion System designed to provide a reliable assessment of the occurrence of Foreign Object Damage (FOD) in a turbofan engine is presented. The FOD-event feature level fusion scheme combines knowledge of shifts in engine gas path performance obtained using a Kalman filter, with bearing accelerometer signal features extracted via wavelet analysis, to positively identify a FOD event. A fuzzy inference system provides basic probability assignments (bpa) based on features extracted from the gas path analysis and bearing accelerometers to a fusion algorithm based on the Dempster-Shafer-Yager Theory of Evidence. Details are provided on the wavelet transforms used to extract the foreign object strike features from the noisy data and on the Kalman filter-based gas path analysis. The system is demonstrated using a turbofan engine combined-effects model (CEM), providing both gas path and rotor dynamic structural response, and is suitable for rapid-prototyping of control and diagnostic systems. The fusion of the disparate data can provide significantly more reliable detection of a FOD event than the use of either method alone. The use of fuzzy inference techniques combined with Dempster-Shafer-Yager Theory of Evidence provides a theoretical justification for drawing conclusions based on imprecise or incomplete data.

  17. 75 FR 57660 - Airworthiness Directives; Rolls-Royce Corporation (RRC) AE 3007A Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-22

    ... series turbofan engines. That AD currently requires performing an eddy current inspection (ECI) or...' prefix Initial Eddy Current Inspection (ECI) or Surface Wave Ultrasonic Testing (SWUT) Inspection (g)...

  18. Peripheral artery bypass - leg - discharge

    MedlinePlus

    ... page: //medlineplus.gov/ency/patientinstructions/000239.htm Peripheral artery bypass - leg - discharge To use the sharing features ... this page, please enable JavaScript. You had peripheral artery bypass surgery to re-route the blood supply ...

  19. The extended distributed microstructure model for gradient-driven transport: A two-scale model for bypassing effective parameters

    NASA Astrophysics Data System (ADS)

    Carr, E. J.; Perré, P.; Turner, I. W.

    2016-12-01

    Numerous problems involving gradient-driven transport processes-e.g., Fourier's and Darcy's law-in heterogeneous materials concern a physical domain that is much larger than the scale at which the coefficients vary spatially. To overcome the prohibitive computational cost associated with such problems, the well-established Distributed Microstructure Model (DMM) provides a two-scale description of the transport process that produces a computationally cheap approximation to the fine-scale solution. This is achieved via the introduction of sparsely distributed micro-cells that together resolve small patches of the fine-scale structure: a macroscopic equation with an effective coefficient describes the global transport and a microscopic equation governs the local transport within each micro-cell. In this paper, we propose a new formulation, the Extended Distributed Microstructure Model (EDMM), where the macroscopic flux is instead defined as the average of the microscopic fluxes within the micro-cells. This avoids the need for any effective parameters and more accurately accounts for a non-equilibrium field in the micro-cells. Another important contribution of the work is the presentation of a new and improved numerical scheme for performing the two-scale computations using control volume, Krylov subspace and parallel computing techniques. Numerical tests are carried out on two challenging test problems: heat conduction in a composite medium and unsaturated water flow in heterogeneous soils. The results indicate that while DMM is more efficient, EDMM is more accurate and is able to capture additional fine-scale features in the solution.

  20. Aeroacoustic Analysis of Fan Noise Reduction With Increased Bypass Nozzle Area

    NASA Technical Reports Server (NTRS)

    Woodward, Richard P.; Hughes, Christopher E.; Podboy, Gary G.

    2005-01-01

    An advanced model turbofan was tested in the NASA Glenn 9-by 15-Foot Low Speed Wind Tunnel (9x15 LSWT) to explore far field acoustic effects of increased bypass nozzle area. This fan stage test was part of the NASA Glenn Fan Broadband Source Diagnostic Test, second entry (SDT2) which acquired aeroacoustic results over a range of test conditions. The baseline nozzle was sized to produce maximum stage performance at cruise condition. However, the wind tunnel testing is conducted near sea level condition. Therefore, in order to simulate and obtain performance at other operating conditions, two additional nozzles were designed and tested one with +5 percent increase in weight flow (+5.4 percent increase in nozzle area compared with the baseline nozzle), sized to simulate the performance at the stage design point (takeoff) condition, and the other with a +7.5 percent increase in weight flow (+10.9 percent increase in nozzle area) sized for maximum weight flow with a fixed nozzle at sea level condition. Measured acoustic benefits with increased nozzle area were very encouraging, showing overall sound power level (OAPWL) reductions of 2 or more dB while the stage thrust actually increased by 2 to 3 percent except for the most open nozzle at takeoff rotor speed where stage performance decreased. Effective perceived noise levels for a 1500 ft engine flyover and 3.35 scale factor showed a similar noise reduction of 2 or more EPNdB. Noise reductions, principally in the level of broadband noise, were observed everywhere in the far field. Laser Doppler Velocimetry measurements taken downstream of the rotor showed that the total turbulent velocity decreased with increasing nozzle flow, which may explain the reduced rotor broadband noise levels.

  1. Superior Vena Cava Bypass

    PubMed Central

    Trainini, Jorge Carlos; Auricchio, Renato; Del Bagno, Horacio Augusto; Federico, Vicente; Acrich, Mario Willie; Osorio, Julio Nestor

    1983-01-01

    A case of superior vena cava obstruction due to carcinoma of unknown origin is reported. A superior vena cava bypass with polytetrafluoroethylene was performed by suturing the prosthesis to the left innominate vein and the right atrium, respectively. Long-term satisfactory results were achieved. Images PMID:15227139

  2. Truly Absorbed Microbial Protein Synthesis, Rumen Bypass Protein, Endogenous Protein, and Total Metabolizable Protein from Starchy and Protein-Rich Raw Materials: Model Comparison and Predictions.

    PubMed

    Parand, Ehsan; Vakili, Alireza; Mesgaran, Mohsen Danesh; van Duinkerken, Gert; Yu, Peiqiang

    2015-07-29

    This study was carried out to measure truly absorbed microbial protein synthesis, rumen bypass protein, and endogenous protein loss, as well as total metabolizable protein, from starchy and protein-rich raw feed materials with model comparisons. Predictions by the DVE2010 system as a more mechanistic model were compared with those of two other models, DVE1994 and NRC-2001, that are frequently used in common international feeding practice. DVE1994 predictions for intestinally digestible rumen undegradable protein (ARUP) for starchy concentrates were higher (27 vs 18 g/kg DM, p < 0.05, SEM = 1.2) than predictions by the NRC-2001, whereas there was no difference in predictions for ARUP from protein concentrates among the three models. DVE2010 and NRC-2001 had highest estimations of intestinally digestible microbial protein for starchy (92 g/kg DM in DVE2010 vs 46 g/kg DM in NRC-2001 and 67 g/kg DM in DVE1994, p < 0.05 SEM = 4) and protein concentrates (69 g/kg DM in NRC-2001 vs 31 g/kg DM in DVE1994 and 49 g/kg DM in DVE2010, p < 0.05 SEM = 4), respectively. Potential protein supplies predicted by tested models from starchy and protein concentrates are widely different, and comparable direct measurements are needed to evaluate the actual ability of different models to predict the potential protein supply to dairy cows from different feedstuffs.

  3. Neuraminidase-1 contributes significantly to the degradation of neuronal B-series gangliosides but not to the bypass of the catabolic block in Tay-Sachs mouse models.

    PubMed

    Timur, Z K; Akyildiz Demir, S; Marsching, C; Sandhoff, R; Seyrantepe, V

    2015-09-01

    Tay–Sachs disease is a severe lysosomal storage disorder caused by mutations in the HEXA gene coding for α subunit of lysosomal β-Hexosaminidase A enzyme, which converts GM2 to GM3 ganglioside. HexA(−/−) mice, depleted of the β-Hexosaminidase A iso-enzyme, remain asymptomatic up to 1 year of age because of a metabolic bypass by neuraminidase(s). These enzymes remove a sialic acid residue converting GM2 to GA2, which is further degraded by the still intact β-Hexosaminidase B iso-enzyme into lactosylceramide. A previously identified ganglioside metabolizing neuraminidase, Neu4, is abundantly expressed in the mouse brain and has activity against gangliosides like GM2in vitro. Neu4(−/−) mice showed increased GD1a and decreased GM1 ganglioside in the brain suggesting the importance of the Neu4 in ganglioside catabolism. Mice with targeted disruption of both HexA and Neu4 genes showed accumulating GM2 ganglioside and epileptic seizures with 40% penetrance, indicating that the neuraminidase Neu4 is a modulatory gene, but may not be the only neuraminidase contributing to the metabolic bypass in HexA(−/−) mice. Therefore, we elucidated the biological role of neuraminidase-1 in ganglioside degradation in mouse. Analysis of HexA(−/−) Neu1(−/−) and HexA(−/−) Neu4(−/−) Neu1(−/−) mice models showed significant contribution of neuraminidase-1 on B-series ganglioside degradation in the brain. Therefore, we speculate that other neuraminidase/neuraminidases such as Neu2 and/or Neu3 might be also involved in the ganglioside degradation pathway in HexA(−/−) mice.

  4. Triiodothyronine increases myocardial function and pyruvate entry into the citric acid cycle after reperfusion in a model of infant cardiopulmonary bypass.

    PubMed

    Olson, Aaron K; Bouchard, Bertrand; Ning, Xue-Han; Isern, Nancy; Rosiers, Christine Des; Portman, Michael A

    2012-03-01

    Triiodothyronine (T3) supplementation improves clinical outcomes in infants after cardiac surgery using cardiopulmonary bypass by unknown mechanisms. We utilized a translational model of infant cardiopulmonary bypass to test the hypothesis that T3 modulates pyruvate entry into the citric acid cycle (CAC), thereby providing the energy support for improved cardiac function after ischemia-reperfusion (I/R). Neonatal piglets received intracoronary [2-(13)Carbon((13)C)]pyruvate for 40 min (8 mM) during control aerobic conditions (control) or immediately after reperfusion (I/R) from global hypothermic ischemia. A third group (I/R-Tr) received T3 (1.2 μg/kg) during reperfusion. We assessed absolute CAC intermediate levels and flux parameters into the CAC through oxidative pyruvate decarboxylation (PDC) and anaplerotic carboxylation (PC) using [2-(13)C]pyruvate and isotopomer analysis by gas and liquid chromatography-mass spectrometry and (13)C-nuclear magnetic resonance spectroscopy. When compared with I/R, T3 (group I/R-Tr) increased cardiac power and oxygen consumption after I/R while elevating flux of both PDC and PC (∼4-fold). Although neither I/R nor I/R-Tr modified absolute CAC levels, T3 inhibited I/R-induced reductions in their molar percent enrichment. Furthermore, (13)C-labeling of CAC intermediates suggests that T3 may decrease entry of unlabeled carbons at the level of oxaloacetate through anaplerosis or exchange reaction with asparate. T3 markedly enhances PC and PDC fluxes, thereby providing potential substrate for elevated cardiac function after reperfusion. This T3-induced increase in pyruvate fluxes occurs with preservation of the CAC intermediate pool. Our labeling data raise the possibility that T3 reduces reliance on amino acids for anaplerosis after reperfusion.

  5. Convection enhanced drug delivery of BDNF through a microcannula in a rodent model to strengthen connectivity of a peripheral motor nerve bridge model to bypass spinal cord injury.

    PubMed

    Martin Bauknight, W; Chakrabarty, Samit; Hwang, Brian Y; Malone, Hani R; Joshi, Shailendra; Bruce, Jeffrey N; Sander Connolly, E; Winfree, Christopher J; Cunningham, Miles G; Martin, John H; Haque, Raqeeb

    2012-04-01

    Models employing peripheral nerve to bypass spinal cord injury (SCI), although highly promising, may benefit from improved nerve regeneration and motor bridge connectivity. Recent studies have demonstrated that neuronal growth factor-induced enhancement of endogenous neurorestoration may improve neuronal connectivity after severe neurologic injury, particularly if delivered intraparenchymally with zero-order kinetics. We sought to investigate the effect of convection-enhanced delivery of brain-derived neurotrophic factor (BDNF), a neuronal growth factor, on the connectivity of a peripheral motor-nerve bridge in a rodent model using electrophysiology and immunohistochemistry (IHC). Spinal cords of 29 female rats were hemisected at the L1 level. Ipsilateral T13 peripheral nerves were dissected from their muscular targets distally, while maintaining their connections with the spinal cord, and inserted caudal to the injury site to establish the nerve bridge. A microcannula attached to a six-week mini-osmotic pump was used to deliver either BDNF (n=12), saline (n=14), or fluorescein dye (n=3) directly into the spinal cord parenchyma between the site of nerve insertion and hemisection to a depth of 2mm into the area of the lateral motor pool. After four weeks, gastrocnemius muscle activation was assessed electromyographically in five animals from each group. Spinal cords were harvested and analyzed with IHC for cannula-associated injury, and nerve regeneration. Strength of motor bridge connection was illustrated by electrophysiology data. Intraspinal BDNF levels were measured using enzyme-linked immunosorbent assay. IHC revealed increased intraparenchymal BDNF concentration at the nerve bridge insertion site with evidence of minimal trauma from cannulation. BDNF infusion resulted in stronger connections between bridge nerves and spinal motor axons. Bridge nerve electrical stimulation in BDNF-treated rats evoked hind leg electromyogram responses of shorter latency and

  6. Study of quiet turbofan STOL aircraft for short haul transportation

    NASA Technical Reports Server (NTRS)

    Higgins, T. P.; Stout, E. G.; Sweet, H. S.

    1973-01-01

    A study of quiet turbofan short takeoff aircraft for short haul air transportation was conducted. The objectives of the study were to: (1) define representative aircraft configurations, characteristics, and costs associated with their development, (2) identify critical technology and technology related problems to be resolved in successful introduction of representative short haul aircraft, (3) determine relationships between quiet short takeoff aircraft and the economic and social viability of short haul, and (4) identify high payoff technology areas.

  7. Quiet Clean General Aviation Turbofan (QCGAT) technology study, volume 1

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The preliminary design of an engine which satisfies the requirements of a quiet, clean, general aviation turbofan (QCGAT) engine is described. Also an experimental program to demonstrate performance is suggested. The T700 QCGAT engine preliminary design indicates that it will radiate noise at the same level as an aircraft without engine noise, have exhaust emissions within the EPA 1981 Standards, have lower fuel consumption than is available in comparable size engines, and have sufficient life for five years between overhauls.

  8. Software Development for EECU Platform of Turbofan Engine

    NASA Astrophysics Data System (ADS)

    Kim, Bo Gyoung; Kwak, Dohyup; Kim, Byunghyun; Choi, Hee ju; Kong, Changduk

    2017-04-01

    The turbofan engine operation consists of a number of hardware and software. The engine is controlled by Electronic Engine Control Unit (EECU). In order to control the engine, EECU communicates with an aircraft system, Actuator Drive Unit (ADU), Engine Power Unit (EPU) and sensors on the engine. This paper tried to investigate the process form starting to taking-off and aims to design the EECU software mode and defined communication data format. The software is implemented according to the designed software mode.

  9. Conceptual design of single turbofan engine powered light aircraft

    NASA Technical Reports Server (NTRS)

    Snyder, F. S.; Voorhees, C. G.; Heinrich, A. M.; Baisden, D. N.

    1977-01-01

    The conceptual design of a four place single turbofan engine powered light aircraft was accomplished utilizing contemporary light aircraft conventional design techniques as a means of evaluating the NASA-Ames General Aviation Synthesis Program (GASP) as a preliminary design tool. In certain areas, disagreement or exclusion were found to exist between the results of the conventional design and GASP processes. Detail discussion of these points along with the associated contemporary design methodology are presented.

  10. Analysis of turbofan propulsion system weight and dimensions

    NASA Technical Reports Server (NTRS)

    Waters, M. H.; Schairer, E. T.

    1977-01-01

    Weight and dimensional relationships that are used in aircraft preliminary design studies are analyzed. These relationships are relatively simple to prove useful to the preliminary designer, but they are sufficiently detailed to provide meaningful design tradeoffs. All weight and dimensional relationships are developed from data bases of existing and conceptual turbofan engines. The total propulsion system is considered including both engine and nacelle, and all estimating relations stem from physical principles, not statistical correlations.

  11. Utilizing numerical techniques in turbofan inlet acoustic suppressor design

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J.

    1982-01-01

    Numerical theories in conjunction with previously published analytical results are used to augment current analytical theories in the acoustic design of a turbofan inlet nacelle. In particular, a finite element-integral theory is used to study the effect of the inlet lip radius on the far field radiation pattern and to determine the optimum impedance in an actual engine environment. For some single mode JT15D data, the numerical theory and experiment are found to be in a good agreement.

  12. System Noise Prediction of the DGEN 380 Turbofan Engine

    NASA Technical Reports Server (NTRS)

    Berton, Jeffrey J.

    2015-01-01

    The DGEN 380 is a small, separate-flow, geared turbofan. Its manufacturer, Price Induction, is promoting it for a small twinjet application in the emerging personal light jet market. Smaller, and producing less thrust than other entries in the industry, Price Induction is seeking to apply the engine to a 4- to 5-place twinjet designed to compete in an area currently dominated by propeller-driven airplanes. NASA is considering purchasing a DGEN 380 turbofan to test new propulsion noise reduction technologies in a relevant engine environment. To explore this possibility, NASA and Price Induction have signed a Space Act Agreement and have agreed to cooperate on engine acoustic testing. Static acoustic measurements of the engine were made by NASA researchers during July, 2014 at the Glenn Research Center. In the event that a DGEN turbofan becomes a NASA noise technology research testbed, it is in the interest of NASA to develop procedures to evaluate engine system noise metrics. This report documents the procedures used to project the DGEN static noise measurements to flight conditions and the prediction of system noise of a notional airplane powered by twin DGEN engines.

  13. 77 FR 66771 - Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co KG Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-07

    ... Deutschland Ltd & Co KG Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of... Rolls-Royce Deutschland Ltd & Co KG (RRD) BR700-710 series turbofan engines. This proposed AD was... Deutschland Ltd & Co KG, Eschenweg 11, Dahlewitz, 15827 Blankenfelde-Mahlow, Germany; telephone: 49 0...

  14. 78 FR 77382 - Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co KG Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-23

    ... Deutschland Ltd & Co KG Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of...-Royce Deutschland Ltd & Co KG (RRD) BR700-715A1-30, BR700-715B1- 30, and BR700-715C1-30 turbofan engines...-Royce Deutschland Ltd & Co KG, Eschenweg 11, Dahlewitz, 15827 Blankenfelde-Mahlow, Germany; phone: 49...

  15. 78 FR 35752 - Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co KG Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-14

    ... Deutschland Ltd & Co KG Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final...-Royce Deutschland Ltd & Co KG (RRD) BR700-725A1-12 turbofan engines with fuel pump tube part number... Deutschland Ltd & Co KG, Eschenweg 11, Dahlewitz, 15827 Blankenfelde-Mahlow, Germany; phone: 49 0...

  16. 78 FR 59291 - Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co. KG Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-26

    ... Deutschland Ltd & Co. KG Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice... Rolls-Royce Deutschland Ltd & Co. KG (RRD) Tay 620-15, 650-15, and 651- 54 turbofan engines. This... information identified in this proposed AD, contact Rolls-Royce Deutschland Ltd & Co KG, Eschenweg...

  17. 77 FR 30371 - Airworthiness Directives; International Aero Engines AG Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-23

    ... Engines AG Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: We are superseding an existing airworthiness directive (AD) for all International Aero Engines AG (IAE) V2500-A1, V2525-D5 and V2528-D5 turbofan engines, and certain serial numbers (S/Ns) of IAE...

  18. 76 FR 64287 - Airworthiness Directives; General Electric Company CF34-10E Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-18

    ... Company CF34-10E Series Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION... General Electric Company (GE) CF34-10E series turbofan engines. This proposed AD was ] prompted by a... center vent tube) support ring and on the inside diameter of the fan drive shaft at the mating...

  19. 78 FR 34605 - Airworthiness Directives; CFM International S.A. Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-10

    ....A. Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ] ACTION: Notice of proposed...-7B series turbofan engines with certain accessory gearboxes (AGBs) not equipped with a handcranking pad ``oil dynamic seal'' assembly. This proposed AD was prompted by 42 events of total loss of...

  20. 78 FR 5126 - Airworthiness Directives; Rolls-Royce plc Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-24

    ... and corrected, could lead to LP location bearing damage, possibly resulting in uncontained engine... Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule; request for...-Trent 970-84, 970B-84, 972-84, 972B-84, 977- 84, 977B-84, and 980-84 turbofan engines. This AD...

  1. 78 FR 22168 - Airworthiness Directives; International Aero Engines AG Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-15

    ... Engines AG Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: We are adopting a new airworthiness directive (AD) for certain International Aero Engines AG (IAE), V2525-D5 and V2528-D5 turbofan engines, with a certain No. 4 bearing internal scavenge tube and...

  2. 77 FR 73268 - Airworthiness Directives; Rolls-Royce plc Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-10

    ... Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule; request for...) RB211-Trent 900 series turbofan engines. This AD requires inspection of the low pressure turbine (LPT) bearing housing end cover assembly in certain engines and, if necessary, its replacement. This AD...

  3. 78 FR 54149 - Airworthiness Directives; Rolls-Royce plc (RR) Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-03

    ...) Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: We are..., 892B-17, and 895-17 turbofan engines. AD 2012-10-12 required inspecting the intermediate-pressure (IP... compressor rotor shaft, as required by AD 2012- 10-12, to add on-wing ] inspections for the Trent 500...

  4. 75 FR 78881 - Airworthiness Directives; Pratt & Whitney PW4000 Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-17

    ... PW4000 Series Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule... turbofan engines. This AD requires initial and repetitive borescope inspections (BSI) or fluorescent.... We are issuing this AD to prevent failure of the HPC 10th stage disk, uncontained engine failure,...

  5. 75 FR 44725 - Airworthiness Directives; Pratt & Whitney PW4000 Series Turbofan Engines; Correction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-29

    ... PW4000 series turbofan engines. The docket number is incorrect in all three of its locations. This... PW4000 Series Turbofan Engines; Correction AGENCY: Federal Aviation Administration (FAA), DOT. ACTION... Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive...

  6. 77 FR 6666 - Airworthiness Directives; CFM International, S.A. Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-09

    ..., S.A. Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule... CFM56-5B series turbofan engines. This AD was prompted by a normal quality sampling at CFM International.... We are issuing this AD to prevent an inflight shutdown (IFSD) of one or more engines...

  7. 77 FR 13485 - Airworthiness Directives; Rolls-Royce plc Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-07

    ... Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: We are adopting a new airworthiness directive (AD) for RB211- Trent 800 series turbofan engines. This AD requires... prevent uncontained engine failure and damage to the airplane. DATES: This AD becomes effective April...

  8. 78 FR 1776 - Airworthiness Directives; International Aero Engines AG Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-09

    ... Engines AG Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed... Aero Engines AG (IAE), V2525-D5 and V2528-D5 turbofan engines, with a certain number (No.) 4 bearing... prompted by a report of an engine under-cowl fire and commanded in-flight shutdown. This proposed AD...

  9. 78 FR 61168 - Airworthiness Directives; Rolls-Royce plc Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-03

    ... Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: We are..., RB211-535E4-C- 37, and RB211-535E4-B-75 turbofan engines. This AD requires removal of affected parts..., which could result in uncontained engine damage and damage to the airplane. DATES: This AD...

  10. 77 FR 40820 - Airworthiness Directives; Rolls-Royce plc Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-11

    ... Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed rulemaking... turbofan engines. This proposed AD was prompted by an investigation by RR concluding that certain... uncontained IP turbine disc failure, engine failure, and damage to the airplane. DATES: We must...

  11. 76 FR 82202 - Airworthiness Directives; International Aero Engines AG Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-30

    ... Engines AG Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed... International Aero Engines AG (IAE) V2500-A1, V2525-D5 and V2528-D5 turbofan engines, and certain serial numbers... engines. The existing AD currently requires initial and repetitive on-wing ultrasonic inspections...

  12. 77 FR 20508 - Airworthiness Directives; Rolls-Royce plc Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-05

    ... Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule; request for..., RB211- Trent 892B-17, and RB211-Trent 895-17 turbofan engines. That AD currently requires initial and... prevent LP compressor blades from failing due to blade root cracks, which could lead to uncontained...

  13. 75 FR 14375 - Airworthiness Directives; Pratt & Whitney (PW) PW4000 Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-25

    ...) PW4000 Series Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of..., PW4156, PW4156A, PW4158, PW4164, PW4168, PW4168A, PW4460, and PW4462 turbofan engines. This proposed AD... proposed AD. FOR FURTHER INFORMATION CONTACT: Rose Len, Aerospace Engineer, Engine Certification...

  14. 75 FR 61114 - Airworthiness Directives; Rolls-Royce plc RB211-Trent 800 Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-04

    ... Directives; Rolls-Royce plc RB211-Trent 800 Series Turbofan Engines AGENCY: Federal Aviation Administration.... Fax: (202) 493-2251. Contact Rolls-Royce plc, P.O. Box 31, Derby, England, DE248BJ; telephone: 011-44... proposed AD, for Rolls- Royce plc RB211-Trent 800 series turbofan engines. That proposed AD would...

  15. 77 FR 12755 - Airworthiness Directives; Pratt & Whitney (PW) Division Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-02

    ... turbofan engines. This proposed AD was prompted by reports of 3rd and 4th stage vane fractures in the low pressure turbine (LPT) of certain PW4000-94'' and PW4000-100'' turbofan engines. These fractures caused an... to prevent 3rd and 4th stage vane fractures in the LPT, which could damage the LPT rotor and lead...

  16. 75 FR 77570 - Airworthiness Directives; General Electric Company CF6 Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-13

    ...) for General Electric (GE) CF6-45/-50 series and CF6-80A series turbofan engines with certain part... Federal Aviation Administration 14 CFR Part 39 RIN 2120-AA64 Airworthiness Directives; General Electric Company CF6 Series Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice...

  17. Low speed test of a high-bypass-ratio propulsion system with an asymmetric inlet designed for a tilt-nacelle V/STOL airplane

    NASA Technical Reports Server (NTRS)

    Syberg, J.

    1978-01-01

    A large scale model of a lift/cruise fan inlet designed for a tilt nacelle V/STOL airplane was tested with a high bypass ratio turbofan. Testing was conducted at low freestream velocities with inlet angles of attack ranging from 0 deg to 120 deg. The operating limits for the nacelle were found to be related to inlet boundary layer separation. Small separations originating in the inlet diffuser cause little or no performance degradation. However, at sufficiently severe freestream conditions the separation changes abruptly to a lip separation. This change is associated with a significant reduction in nacelle net thrust as well as a sharp increase in fan blade vibratory stresses. Consequently, the onset of lip separation is regarded as the nacelle operating limit. The test verified that the asymmetric inlet design will provide high performance and stable operation at the design forward speed and angle of attack conditions. At some of these, however, operation near the lower end of the design inlet airflow range is not feasible due to the occurrence of lip separation.

  18. Alongshore sediment bypassing as a control on river mouth morphodynamics

    NASA Astrophysics Data System (ADS)

    Nienhuis, Jaap H.; Ashton, Andrew D.; Nardin, William; Fagherazzi, Sergio; Giosan, Liviu

    2016-04-01

    River mouths, shoreline locations where fluvial and coastal sediments are partitioned via erosion, trapping, and redistribution, are responsible for the ultimate sedimentary architecture of deltas and, because of their dynamic nature, also pose great management and engineering challenges. To investigate the interaction between fluvial and littoral processes at wave-dominated river mouths, we modeled their morphologic evolution using the coupled hydrodynamic and morphodynamic model Delft3D-SWAN. Model experiments replicate alongshore migration of river mouths, river mouth spit development, and eventual spit breaching, suggesting that these are emergent phenomena that can develop even under constant fluvial and wave conditions. Furthermore, we find that sediment bypassing of a river mouth develops though feedbacks between waves and river mouth morphology, resulting in either continuous bypassing pathways or episodic bar bypassing pathways. Model results demonstrate that waves refracting into the river mouth bar create a zone of low alongshore sediment transport updrift of the river mouth, which reduces sediment bypassing. Sediment bypassing, in turn, controls the river mouth migration rate and the size of the river mouth spit. As a result, an intermediate amount of river discharge maximizes river mouth migration. The fraction of alongshore sediment bypassing can be predicted from the balance between the jet and the wave momentum flux. Quantitative comparisons show a match between our modeled predictions of river mouth bypassing and migration rates observed in natural settings.

  19. Pulmonary microRNA expression profiling in an immature piglet model of cardiopulmonary bypass-induced acute lung injury.

    PubMed

    Li, Wenlei; Ma, Kai; Zhang, Sen; Zhang, Hao; Liu, Jinping; Wang, Xu; Li, Shoujun

    2015-04-01

    After surgery performed under cardiopulmonary bypass (CPB), severe lung injury often occurs in infants. MicroRNAs (miRNAs) are potentially involved in diverse pathophysiological processes via regulation of gene expression. The objective of this study was to investigate differentially expressed miRNAs and their potential target genes in immature piglet lungs in response to CPB. Fourteen piglets aged 18.6 ± 0.5 days were equally divided into two groups that underwent sham sternotomy or CPB. The duration of aortic cross-clamping was 2 h, followed by 2 h reperfusion. Lung injury was evaluated by lung function indices, levels of cytokines, and histological changes. We applied miRNA microarray and quantitative real-time polymerase chain reaction (qRT-PCR) analysis to determine miRNA expression. Meanwhile, qRT-PCR and enzyme-linked immunosorbent assay were used for validation of predicted mRNA targets. The deterioration of lung function and histopathological changes revealed the piglets' lungs were greatly impaired due to CPB. The levels of tumor necrosis factor alpha, interleukin 6, and interleukin 10 increased in the lung tissue after CPB. Using miRNA microarray, statistically significant differences were found in the levels of 16 miRNAs in the CPB group. Up-regulation of miR-21 was verified by PCR. We also observed down-regulation in the levels of miR-127, miR-145, and miR-204, which were correlated with increases in the expression of the products of their potential target genes PIK3CG, PTGS2, ACE, and IL6R in the CPB group, suggesting a potential role for miRNA in the regulation of inflammatory response. Our results show that CPB induces severe lung injury and dynamic changes in miRNA expression in piglet lungs. Moreover, the changes in miRNA levels and target gene expression may provide a basis for understanding the pathogenesis of CPB-induced injury to immature lungs.

  20. Access to the bypassed stomach after gastric bypass.

    PubMed

    Fobi, M A; Chicola, K; Lee, H

    1998-06-01

    The gastric bypass (GBP) Operation is progressively being widely used to treat severe obesity. One problem with this operation is that it leaves the bypassed segment of the gastrointestinal tract not readily available for either mechanical, radiological or endoscopic evaluation. We have addressed this problem by putting a gastrostomy tube in the bypassed stomach at the time of the GBP. A radio-opaque marker placed around the gastrostomy site enables easy radiological localization of and thus easy percutaneous access to the bypassed stomach. The surgical technique is presented.

  1. Possible Mechanisms for Turbofan Engine Ice Crystal Icing at High Altitude

    NASA Technical Reports Server (NTRS)

    Tsao, Jen-Ching; Struk, Peter M.; Oliver, Michael

    2014-01-01

    A thermodynamic model is presented to describe possible mechanisms of ice formation on unheated surfaces inside a turbofan engine compression system from fully glaciated ice crystal clouds often formed at high altitude near deep convective weather systems. It is shown from the analysis that generally there could be two distinct types of ice formation: (1) when the "surface freezing fraction" is in the range of 0 to 1, dominated by the freezing of water melt from fully or partially melted ice crystals, the ice structure is formed from accretion with strong adhesion to the surface, and (2) when the "surface melting fraction" is the range of 0 to 1, dominated by the further melting of ice crystals, the ice structure is formed from accumulation of un-melted ice crystals with relatively weak bonding to the surface. The model captures important qualitative trends of the fundamental ice-crystal icing phenomenon reported earlier1,2 from the research collaboration work by NASA and the National Research Council (NRC) of Canada. Further, preliminary analysis of test data from the 2013 full scale turbofan engine ice crystal icing test3 conducted in the NASA Glenn Propulsion Systems Laboratory (PSL) has also suggested that (1) both types of ice formation occurred during the test, and (2) the model has captured some important qualitative trend of turning on (or off) the ice crystal ice formation process in the tested engine low pressure compressor (LPC) targeted area under different icing conditions that ultimately would lead to (or suppress) an engine core roll back (RB) event.

  2. Possible Mechanisms for Turbofan Engine Ice Crystal Icing at High Altitude

    NASA Technical Reports Server (NTRS)

    Tsao, Jen-Ching; Struk, Peter M.; Oliver, Michael J.

    2016-01-01

    A thermodynamic model is presented to describe possible mechanisms of ice formation on unheated surfaces inside a turbofan engine compression system from fully glaciated ice crystal clouds often formed at high altitude near deep convective weather systems. It is shown from the analysis that generally there could be two distinct types of ice formation: (1) when the "surface freezing fraction" is in the range of 0 to 1, dominated by the freezing of water melt from fully or partially melted ice crystals, the ice structure is formed from accretion with strong adhesion to the surface, and (2) when the "surface melting fraction" is the range of 0 to 1, dominated by the further melting of ice crystals, the ice structure is formed from accumulation of un-melted ice crystals with relatively weak bonding to the surface. The model captures important qualitative trends of the fundamental ice-crystal icing phenomenon reported earlier (Refs. 1 and 2) from the research collaboration work by NASA and the National Research Council (NRC) of Canada. Further, preliminary analysis of test data from the 2013 full scale turbofan engine ice crystal icing test (Ref. 3) conducted in the NASA Glenn Propulsion Systems Laboratory (PSL) has also suggested that (1) both types of ice formation occurred during the test, and (2) the model has captured some important qualitative trend of turning on (or off) the ice crystal ice formation process in the tested engine low pressure compressor (LPC) targeted area under different icing conditions that ultimately would lead to (or suppress) an engine core roll back (RB) event.

  3. Effect of Two Advanced Noise Reduction Technologies on the Aerodynamic Performance of an Ultra High Bypass Ratio Fan

    NASA Technical Reports Server (NTRS)

    Hughes, Christoper E.; Gazzaniga, John A.

    2013-01-01

    A wind tunnel experiment was conducted in the NASA Glenn Research Center anechoic 9- by 15-Foot Low-Speed Wind Tunnel to investigate two new advanced noise reduction technologies in support of the NASA Fundamental Aeronautics Program Subsonic Fixed Wing Project. The goal of the experiment was to demonstrate the noise reduction potential and effect on fan model performance of the two noise reduction technologies in a scale model Ultra-High Bypass turbofan at simulated takeoff and approach aircraft flight speeds. The two novel noise reduction technologies are called Over-the-Rotor acoustic treatment and Soft Vanes. Both technologies were aimed at modifying the local noise source mechanisms of the fan tip vortex/fan case interaction and the rotor wake-stator interaction. For the Over-the-Rotor acoustic treatment, two noise reduction configurations were investigated. The results showed that the two noise reduction technologies, Over-the-Rotor and Soft Vanes, were able to reduce the noise level of the fan model, but the Over-the-Rotor configurations had a significant negative impact on the fan aerodynamic performance; the loss in fan aerodynamic efficiency was between 2.75 to 8.75 percent, depending on configuration, compared to the conventional solid baseline fan case rubstrip also tested. Performance results with the Soft Vanes showed that there was no measurable change in the corrected fan thrust and a 1.8 percent loss in corrected stator vane thrust, which resulted in a total net thrust loss of approximately 0.5 percent compared with the baseline reference stator vane set.

  4. Automated procedure for developing hybrid computer simulations of turbofan engines. Part 1: General description

    NASA Technical Reports Server (NTRS)

    Szuch, J. R.; Krosel, S. M.; Bruton, W. M.

    1982-01-01

    A systematic, computer-aided, self-documenting methodology for developing hybrid computer simulations of turbofan engines is presented. The methodology that is pesented makes use of a host program that can run on a large digital computer and a machine-dependent target (hybrid) program. The host program performs all the calculations and data manipulations that are needed to transform user-supplied engine design information to a form suitable for the hybrid computer. The host program also trims the self-contained engine model to match specified design-point information. Part I contains a general discussion of the methodology, describes a test case, and presents comparisons between hybrid simulation and specified engine performance data. Part II, a companion document, contains documentation, in the form of computer printouts, for the test case.

  5. Analytical investigation of adaptive control of radiated inlet noise from turbofan engines

    NASA Technical Reports Server (NTRS)

    Risi, John D.; Burdisso, Ricardo A.

    1994-01-01

    An analytical model has been developed to predict the resulting far field radiation from a turbofan engine inlet. A feedforward control algorithm was simulated to predict the controlled far field radiation from the destructive combination of fan noise and secondary control sources. Numerical results were developed for two system configurations, with the resulting controlled far field radiation patterns showing varying degrees of attenuation and spillover. With one axial station of twelve control sources and error sensors with equal relative angular positions, nearly global attenuation is achieved. Shifting the angular position of one error sensor resulted in an increase of spillover to the extreme sidelines. The complex control inputs for each configuration was investigated to identify the structure of the wave pattern created by the control sources, giving an indication of performance of the system configuration. It is deduced that the locations of the error sensors and the control source configuration are equally critical to the operation of the active noise control system.

  6. Granulocyte colony stimulating factor reduces brain injury in a cardiopulmonary bypass-circulatory arrest model of ischemia in a newborn piglet

    PubMed Central

    Pastuszko, Peter; Schears, Gregory J.; Greeley, William J.; Kubin, Joanna; Wilson, David F.; Pastuszko, Anna

    2014-01-01

    Background Ischemic brain injury continues to be of major concern in patients undergoing cardiopulmonary bypass (CPB) surgery for congenital heart disease. Striatum and hippocampus are particularly vulnerable to injury during these processes. Our hypothesis is that the neuronal injury resulting from CPB and the associated circulatory arrest can be at least partly ameliorated by pre-treatment with granulocyte colony stimulating factor (G-CSF). Material and Methods Fourteen male newborn piglets were assigned to three groups: deep hypothermic circulatory arrest (DHCA), DHCA with G-CSF, and sham-operated. The first two groups were placed on CPB, cooled to 18°C, subjected to 60 min of DHCA, re-warmed and recovered for 8-9 hrs. At the end of experiment, the brains were perfused, fixed and cut into 10 μm transverse sections. Apoptotic cells were visualized by in-situ DNA fragmentation assay (TUNEL), with the density of injured cells expressed as a mean number ± SD per mm2. Results The number of injured cells in the striatum and CA1 and CA3 regions of the hippocampus increased significantly following DHCA. In the striatum, the increase was from 0.46±0.37 to 3.67±1.57 (p=0.002); in the CA1, from 0.11±0.19 to 5.16±1.57 (p=0.001), and in the CA3, from 0.28±0.25 to 2.98±1.82 (p=0.040). Injection of G-CSF prior to bypass significantly reduced the number of injured cells in the striatum and CA1 region, by 51% and 37%, respectively. In the CA3 region, injured cell density did not differ between the G-CSF and control group. Conclusion In a model of hypoxic brain insult associated with CPB, G-CSF significantly reduces neuronal injury in brain regions important for cognitive functions, suggesting it can significantly improve neurological outcomes from procedures requiring DHCA. PMID:25082120

  7. Protection of semiconductor converters for controlled bypass reactors

    SciTech Connect

    Dolgopolov, A. G.; Akhmetzhanov, N. G.; Karmanov, V. F.

    2010-05-15

    Possible ways of protecting thyristor converters in systems for magnetizing 110 - 500 kV controlled bypass reactors during switching and automatic reclosing are examined based on experience with the development of equipment, line tests, and mathematical modelling.

  8. Receptor for advanced glycation end products involved in lung ischemia reperfusion injury in cardiopulmonary bypass attenuated by controlled oxygen reperfusion in a canine model.

    PubMed

    Rong, Jian; Ye, Sheng; Liang, Meng-ya; Chen, Guang-xian; Liu, Hai; Zhang, Jin-Xin; Wu, Zhong-kai

    2013-01-01

    Controlled oxygen reperfusion could protect the lung against ischemia-reperfusion injury in cardiopulmonary bypass (CPB) by downregulating high mobility group box 1 (HMGB1), a high affinity receptor of HMGB1. This study investigated the effect of controlled oxygen reperfusion on receptor for advanced glycation end products (RAGE) expression and its downstream effects on lung ischemia-reperfusion injury. Fourteen canines received CPB with 60 minutes of aortic clamping and cardioplegic arrest followed by 90 minutes of reperfusion. Animals were randomized to receive 80% FiO2 during the entire procedure (control group) or to a test group receiving a controlled oxygen reperfusion protocol. Pathologic changes in lung tissues, RAGE expression, serum interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were evaluated. The lung pathologic scores after 25 and 90 minutes of reperfusion were significantly lower in the test group compared with the control group (p < 0.001). RAGE expression, TNF-α, and IL-6 were downregulated by controlled oxygen treatment (p < 0.001). RAGE might be involved in the lung ischemia-reperfusion injury in canine model of CPB, which was downregulated by controlled oxygen reperfusion.

  9. Bypass surgery for lower extremity limb salvage: vein bypass.

    PubMed

    El-Sayed, Hosam F

    2012-01-01

    Bypass surgery for limb salvage in cases of chronic limb ischemia is a well-established treatment modality. Use of an autogenous vein provides the best conduit for infrainguinal arterial bypass procedures, particularly for bypass to the infrapopliteal arteries. In this article, we discuss infrainguinal vein bypass surgery including indications, perioperative care, and long-term follow up. We also discuss the outcomes of the procedure with regard to patient survival and limb salvage. The autogenous vein continues to be the best available conduit with the highest patency rate and the best treatment option. Compared to all other revascularization options for infrainguinal disease, the vein bypass has the best limb salvage and long-term survival in patients appropriately selected for the procedure.

  10. Predictors of Health-Promoting Behaviors in Coronary Artery Bypass Surgery Patients: An Application of Pender’s Health Promotion Model

    PubMed Central

    Mohsenipoua, Hossein; Majlessi, Fereshteh; Shojaeizadeh, Davood; Rahimiforooshani, Abbas; Ghafari, Rahman; Habibi, Valiollah

    2016-01-01

    Background Advances in coronary artery surgery have reduced patient morbidity and mortality. Nevertheless, patients still have to face physical, psychological, and social problems after discharge from hospital. Objectives The objective of this study was to determine the efficacy of Pender’s health promotion model in predicting cardiac surgery patients’ lifestyles in Iran. Methods This cross-sectional study comprised 220 patients who had undergone coronary artery bypass graft (CABG) surgery in Mazandaran province (Iran) in 2015. The subjects were selected using a simple random sampling method. The data were collected via (1) the health-promoting lifestyle profile II (HPLP II) and (2) a self-designed questionnaire that included two main sections: demographic characteristics and questions based on the health-promoting model constructs. Results Spiritual growth (28.77 ± 5.03) and physical activity (15.79 ± 5.08) had the highest and lowest scores in the HPLP II dimensions, respectively. All the health promotion model variables were significant predictors of health-promoting behaviors and explained 69% of the variance in health-promoting behaviors. Three significant predictors were estimated using regression coefficients: behavioral feelings (β = 0.390, P < 0.001), perceived benefits (β = 0.209, P < 0.001), and commitment to a plan of action (β = 0.347, P < 0.001). Conclusions According to the results of the study, health-promoting model-based self-care behaviors can help identify and predict cardiac surgery patients’ lifestyles in Iran. This pattern can be used as a framework for discharge planning and the implementation of educational interventions to improve the lifestyles of CABG patients. PMID:28144467

  11. Study of quiet turbofan STOL aircraft for short haul transportation

    NASA Technical Reports Server (NTRS)

    Higgins, T. P.; Stout, E. G.; Sweet, H. S.

    1973-01-01

    Conceptual designs of Quiet Turbofan STOL Short-Haul Transport Aircraft for the mid-1980 time period are developed and analyzed to determine their technical, operational, and economic feasibility. A matrix of aircraft using various high-lift systems and design parameters are considered. Variations in aircraft characteristics, airport geometry and location, and operational techniques are analyzed systematically to determine their effects on the market, operating economics, and community acceptance. In these studies, the total systems approach is considered to be critically important in analyzing the potential of STOL aircraft to reduce noise pollution and alleviate the increasing air corridor and airport congestion.

  12. The Design and Testing of a Miniature Turbofan Engine

    NASA Technical Reports Server (NTRS)

    Cosentino, Gary B.; Murray, James E.

    2009-01-01

    Off-the-shelf jet propulsion in the 50 - 500 lb thrust class sparse. A true twin-spool turbofan in this range does not exist. Adapting an off-the-shelf turboshaft engine is feasible. However the approx.10 Hp SPT5 can t quite make 50 lbs. of thrust. Packaging and integration is challenging, especially the exhaust. Building on our engine using a 25 Hp turboshaft seems promising if the engine becomes available. Test techniques used, though low cost, adequate for the purpose.

  13. Spiritual Bypass: A Preliminary Investigation

    ERIC Educational Resources Information Center

    Cashwell, Craig S.; Glosoff, Harriet L.; Hammond, Cheree

    2010-01-01

    The phenomenon of spiritual bypass has received limited attention in the transpersonal psychology and counseling literature and has not been subjected to empirical inquiry. This study examines the phenomenon of spiritual bypass by considering how spirituality, mindfulness, alexithymia (emotional restrictiveness), and narcissism work together to…

  14. Interference effects of very high bypass ratio nacelle installations on a low-wing transport

    NASA Technical Reports Server (NTRS)

    Ingraldi, Anthony M.; Re, Richard J.; Pendergraft, Odis C., Jr.; Kariya, Timmy T.

    1991-01-01

    A twin-engine, low-wing transport model, with a supercritical wing designed for a cruise Mach number of 0.77 and a lift coefficient of 0.55 was tested in the 16-Foot Transonic Tunnel at NASA Langley Research Center. The purpose of this test was to compare the wing/nacelle interference effects of superfans (BPR 18) with the interference effects of advanced turbofans (BPR 6). Flow-through nacelles were used. Forces and moments on the complete model were measured using a strain gage balance, and extensive surface static pressure measurements were made on the model's wing, nacelles, and pylons. Results of the investigation indicate that superfan nacelles can be installed with approximately the same drag penalty as conventional turbofan nacelles.

  15. Compliant model of a coupled sequential coronary arterial bypass graft: effects of vessel wall elasticity and non-Newtonian rheology on blood flow regime and hemodynamic parameters distribution.

    PubMed

    Kabinejadian, Foad; Ghista, Dhanjoo N

    2012-09-01

    We have recently developed a novel design for coronary arterial bypass surgical grafting, consisting of coupled sequential side-to-side and end-to-side anastomoses. This design has been shown to have beneficial blood flow patterns and wall shear stress distributions which may improve the patency of the CABG, as compared to the conventional end-to-side anastomosis. In our preliminary computational simulation of blood flow of this coupled sequential anastomoses design, the graft and the artery were adopted to be rigid vessels and the blood was assumed to be a Newtonian fluid. Therefore, the present study has been carried out in order to (i) investigate the effects of wall compliance and non-Newtonian rheology on the local flow field and hemodynamic parameters distribution, and (ii) verify the advantages of the CABG coupled sequential anastomoses design over the conventional end-to-side configuration in a more realistic bio-mechanical condition. For this purpose, a two-way fluid-structure interaction analysis has been carried out. A finite volume method is applied to solve the three-dimensional, time-dependent, laminar flow of the incompressible, non-Newtonian fluid; the vessel wall is modeled as a linearly elastic, geometrically non-linear shell structure. In an iteratively coupled approach the transient shell equations and the governing fluid equations are solved numerically. The simulation results indicate a diameter variation ratio of up to 4% and 5% in the graft and the coronary artery, respectively. The velocity patterns and qualitative distribution of wall shear stress parameters in the distensible model do not change significantly compared to the rigid-wall model, despite quite large side-wall deformations in the anastomotic regions. However, less flow separation and reversed flow is observed in the distensible models. The wall compliance reduces the time-averaged wall shear stress up to 32% (on the heel of the conventional end-to-side model) and somewhat

  16. Endothelial Dysfunction of Bypass Graft: Direct Comparison of In Vitro and In Vivo Models of Ischemia-Reperfusion Injury

    PubMed Central

    Veres, Gábor; Hegedűs, Péter; Barnucz, Enikő; Zöller, Raphael; Klein, Stephanie; Schmidt, Harald; Radovits, Tamás; Korkmaz, Sevil; Karck, Matthias; Szabó, Gábor

    2015-01-01

    Background Although, ischemia/reperfusion induced vascular dysfunction has been widely described, no comparative study of in vivo- and in vitro-models exist. In this study, we provide a direct comparison between models (A) ischemic storage and in-vitro reoxygenation (B) ischemic storage and in vitro reperfusion (C) ischemic storage and in-vivo reperfusion. Methods and Results Aortic arches from rats were stored for 2 hours in saline. Arches were then (A) in vitro reoxygenated (B) in vitro incubated in hypochlorite for 30 minutes (C) in vivo reperfused after heterotransplantation (2, 24 hours and 7 days reperfusion). Endothelium-dependent and independent vasorelaxations were assessed in organ bath. DNA strand breaks were assessed by TUNEL-method, mRNA expressions (caspase-3, bax, bcl-2, eNOS) by quantitative real-time PCR, proteins by Western blot analysis and the expression of CD-31 by immunochemistry. Endothelium-dependent maximal relaxation was drastically reduced in the in-vivo models compared to ischemic storage and in-vitro reperfusion group, and no difference showed between ischemic storage and control group. CD31-staining showed significantly lower endothelium surface ratio in-vivo, which correlated with TUNEL-positive ratio. Increased mRNA and protein levels of pro- and anti-apoptotic gens indicated a significantly higher damage in the in-vivo models. Conclusion Even short-period of ischemia induces severe endothelial damage (in-vivo reperfusion model). In-vitro models of ischemia-reperfusion injury can be limitedly suited for reliable investigations. Time course of endothelial stunning is also described. PMID:25875813

  17. Bypass diode integration

    NASA Technical Reports Server (NTRS)

    Shepard, N. F., Jr.

    1981-01-01

    Protective bypass diodes and mounting configurations which are applicable for use with photovoltaic modules having power dissipation requirements in the 5 to 50 watt range were investigated. Using PN silicon and Schottky diode characterization data on packaged diodes and diode chips, typical diodes were selected as representative for each range of current carrying capacity, an appropriate heat dissipating mounting concept along with its environmental enclosure was defined, and a thermal analysis relating junction temperature as a function of power dissipation was performed. In addition, the heat dissipating mounting device dimensions were varied to determine the effect on junction temperature. The results of the analysis are presented as a set of curves indicating junction temperature as a function of power dissipation for each diode package.

  18. Cardiopulmonary Bypass Without Heparin.

    PubMed

    Rehfeldt, Kent H; Barbara, David W

    2016-03-01

    Due to familiarity, short half-life, ease of monitoring, and the availability of a reversal agent, heparin remains the anticoagulant of choice for cardiac operations requiring cardiopulmonary bypass (CPB). However, occasionally patients require CPB but should not receive heparin, most often because of acute or subacute heparin-induced thrombocytopenia (HIT). In these cases, if it is not feasible to wait for the disappearance of HIT antibodies, an alternative anticoagulant must be selected. A number of non-heparin anticoagulant options have been explored. However, current recommendations suggest the use of a direct thrombin inhibitor such as bivalirudin. This review describes the use of heparin alternatives for the conduct of CPB with a focus on the direct thrombin inhibitors.

  19. The effect of chemical carcinogens on DNA bypass replication and the development of in vitro and in vivo models for chemical mutagenesis

    SciTech Connect

    Yamanishi, D.T.

    1989-01-01

    This study with the testing of a hypothetical mechanism whereby mammalian cells are able to replicate their DNA past polycyclic aromatic hydrocarbon DNA adducts. The second objective of this thesis work was to develop both in vivo and in vitro models to study the induction of mutations in a target human gene by chemical carcinogens from two different classes, polycyclic aromatic hydrocarbons and nitrosamines. To approach the hypothetical mechanism of bypass replication in mammalian cells, synchronized Chinese hamster ovary cells were treated with benzo(a)pyrene, 7{beta}, 8{alpha}-dihydroxy-9{alpha}, 10{alpha}-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene (BPDEI). Using the pH step alkaline elution assay, it was found that the reduced rate of S phase progression was due to a delay in the appearance of multiple replicon size nascent DNA. It was determined using agarose gel electrophoresis that the ligation of Okazaki size replication intermediates was blocked in BPDE I-treated, synchronized CHO cells. To study mutagenesis of a specific sequence induced by chemical carcinogens, the human c-Ha-ras proto-oncogene was transfected into the mouse fibroblast cell line, NIH 3T3. Transfected NIH 3T3 cell lines (HHRN 1-4) were isolated that had a low copy number of the human c-Ha-ras proto-oncogene and a non-transformed phenotype. Treatment of the HHRN cell lines with the nitrosamine, N-methyl-nitroso-N{prime}-nitroguanidine (MNNG) resulted in transformed NIH 3T3 foci. In vitro MNNG treatment of the plasmid, z-6, and transfection into NIH 3T3 cells led to the isolation of transformed cell lines.

  20. The Effect of Utilizing Organizational Culture Improvement Model of Patient Education on Coronary Artery Bypass Graft Patients’ Anxiety and Satisfaction: Theory Testing

    PubMed Central

    Farahani, Mansoureh Ashghali; Ghaffari, Fatemeh; Norouzinezhad, Faezeh; Orak, Roohangiz Jamshidi

    2016-01-01

    Introduction Due to the increasing prevalence of arteriosclerosis and the mortality caused by this disease, Coronary Artery Bypass Graft (CABG) has become one of the most common surgical procedures. Utilization of patient education is approved as an effective solution for increasing patient survival and outcomes of treatment. However, failure to consider different aspects of patient education has turned this goal into an unattainable one. The objective of this research was to determine the effect of utilizing the organizational culture improvement model of patient education on CABG patients’ anxiety and satisfaction. Methods The present study is a randomized controlled trial. This study was conducted on eighty CABG patients. The patients were selected from the CCU and Post-CCU wards of a hospital affiliated with Iran University of Medical Sciences in Tehran, Iran, during 2015. Eshpel Burger’s Anxiety Inventory and Patients’ Satisfaction Questionnaire were used to collect the required information. Levels of anxiety and satisfaction of patients before intervention and at the time of release were measured. The intervention took place after preparing a programmed package based on the organizational culture improvement model for the following dimensions: effective communication, participatory decision-making, goal setting, planning, implementation and recording, supervision and control, and improvement of motivation. After recording the data, it was analyzed in the chi-square test, t-independent and Mann-Whitney U tests. The significance level of tests was assumed to be 0.05. SPSS version 18 was also utilized for data analysis. Results Research results revealed that variations in the mean scores of situational and personality anxiety of the control and experiment group were descending following the intervention, but the decrease was higher in the experiment group (p≤0.0001). In addition, the variations of the mean scores of patients’ satisfaction with

  1. Monitoring the conjunctiva for carbon dioxide and oxygen tensions and pH during cardiopulmonary bypass.

    PubMed

    Weiss, Irwin K; Isenberg, Sherwin J; McArthur, David L; Del Signore, Madeline; McDonald, John S

    2011-03-01

    The purpose of this study was to measure, for the first time, multiple physiologic parameters of perfusion (pH, PCO2, PO2, and temperature) from the conjunctiva of adult patients during cardiopulmonary bypass while undergoing cardiothoracic surgery. Ten patients who underwent either intracardiac valve repair, atrial septal defect repair, or coronary artery bypass graft surgery had placement of a sensor which directly measured pH, PCO2, PO2, and temperature from the conjunctiva. Data were stratified into seven phases (0-5 minutes prior to bypass; 0-5, 6-10, and 11-15 minutes after initiation of bypass; 0-5 minutes prior to conclusion of bypass; and 0-5 and 6-10 minutes after bypass) and analyzed using a mixed model analysis.The change in conjunctival pH over the course of measurement was not statistically significant (p = .56). The PCO2 level followed a quadratic pattern, decreasing from a mean pre-bypass level of 37.7 mmHg at baseline prior to the initiation of cardiopulmonary bypass to a nadir of 33.2 mmHg, then increasing to a high of 39.4 mmHg at 6-10 minutes post bypass (p < .01). The PO2 declined from a mean pre-bypass level of 79.5 mmHg to 31.3 mmHg by 6-10 minutes post bypass and even post-bypass, it never returned to baseline values (p < .01). Temperature followed a pattern similar to PCO2 by returning to baseline levels as the patient was re-warmed following bypass (p < .01). There was no evidence of any eye injury or inflammation following the removal of the sensor. In the subjects studied, the conjunctival sensor yielded reproducible measurements during the various phases of cardiopulmonary bypass without ocular injury. Further study is necessary to determine the role of conjunctival measurements in critical settings.

  2. Photovoltaic module bypass diode encapsulation

    NASA Technical Reports Server (NTRS)

    Shepard, N. J., Jr.

    1983-01-01

    The design and processing techniques necessary to incorporate bypass diodes within the module encapsulant are presented. The Semicon PN junction diode cells were selected. Diode junction to heat spreader thermal resistance measurements, performed on a variety of mounted diode chip types and sizes, have yielded values which are consistently below 1 deg C per watt, but show some instability when thermally cycled over the temperature range from -40 to 150 deg C. Three representative experimental modules, each incorporating integral bypass diode/heat spreader assemblies of various sizes, were designed. Thermal testing of these modules enabled the formulation of a recommended heat spreader plate sizing relationship. The production cost of three encapsulated bypass diode/heat spreader assemblies were compared with similarly rated externally mounted packaged diodes. It is concluded that, when proper designed and installed, these bypass diode devices will improve the overall reliability of a terrestrial array over a 20 year design lifetime.

  3. Turbofan noise generation. Volume 1: Analysis

    NASA Technical Reports Server (NTRS)

    Ventres, C. S.; Theobald, M. A.; Mark, W. D.

    1982-01-01

    Computer programs were developed which calculate the in-duct acoustic modes excited by a fan/stator stae operating at subsonic tip speed. Three noise source mechanisms are included: (1) sound generated by the rotor blades interacting with turbulence ingested into, or generated within, the inlet duct; (2) sound generated by the stator vanes interacting with the turbulent wakes of the rotors blades; and (3) sound generated by the stator vanes interacting with the mean velocity deficit wakes of the rotor blades. The fan/stator stage is modeled as an ensemble of blades and vanes of zero camber and thickness enclosed within an infinite hard-walled annular duct. Turbulence drawn into or generated within the inlet duct is modeled as nonhomogeneous and anisotropic random fluid motion, superimposed upon a uniform axial mean flow, and convected with that flow. Equations for the duct mode amplitudes, or expected values of the amplitudes, are derived.

  4. Parametric (On-Design) Cycle Analysis for a Separate-Exhaust Turbofan Engine With Interstage Turbine Burner

    NASA Technical Reports Server (NTRS)

    Liew, K. H.; Urip, E.; Yang, S. L.; Siow, Y. K.; Marek, C. J.

    2005-01-01

    Today s modern aircraft is based on air-breathing jet propulsion systems, which use moving fluids as substances to transform energy carried by the fluids into power. Throughout aero-vehicle evolution, improvements have been made to the engine efficiency and pollutants reduction. The major advantages associated with the addition of ITB are an increase in thermal efficiency and reduction in NOx emission. Lower temperature peak in the main combustor results in lower thermal NOx emission and lower amount of cooling air required. This study focuses on a parametric (on-design) cycle analysis of a dual-spool, separate-flow turbofan engine with an Interstage Turbine Burner (ITB). The ITB considered in this paper is a relatively new concept in modern jet engine propulsion. The ITB serves as a secondary combustor and is located between the high- and the low-pressure turbine, i.e., the transition duct. The objective of this study is to use design parameters, such as flight Mach number, compressor pressure ratio, fan pressure ratio, fan bypass ratio, and high-pressure turbine inlet temperature to obtain engine performance parameters, such as specific thrust and thrust specific fuel consumption. Results of this study can provide guidance in identifying the performance characteristics of various engine components, which can then be used to develop, analyze, integrate, and optimize the system performance of turbofan engines with an ITB. Visual Basic program, Microsoft Excel macrocode, and Microsoft Excel neuron code are used to facilitate Microsoft Excel software to plot engine performance versus engine design parameters. This program computes and plots the data sequentially without forcing users to open other types of plotting programs. A user s manual on how to use the program is also included in this report. Furthermore, this stand-alone program is written in conjunction with an off-design program which is an extension of this study. The computed result of a selected design

  5. Aeroacoustic Analysis of Turbofan Noise Generation

    NASA Technical Reports Server (NTRS)

    Meyer, Harold D.; Envia, Edmane

    1996-01-01

    This report provides an updated version of analytical documentation for the V072 Rotor Wake/Stator Interaction Code. It presents the theoretical derivation of the equations used in the code and, where necessary, it documents the enhancements and changes made to the original code since its first release. V072 is a package of FORTRAN computer programs which calculate the in-duct acoustic modes excited by a fan/stator stage operating in a subsonic mean flow. Sound is generated by the stator vanes interacting with the mean wakes of the rotor blades. In this updated version, only the tonal noise produced at the blade passing frequency and its harmonics, is described. The broadband noise component analysis, which was part of the original report, is not included here. The code provides outputs of modal pressure and power amplitudes generated by the rotor-wake/stator interaction. The rotor/stator stage is modeled as an ensemble of blades and vanes of zero camber and thickness enclosed within an infinite hard-walled annular duct. The amplitude of each propagating mode is computed and summed to obtain the harmonics of sound power flux within the duct for both upstream and downstream propagating modes.

  6. Bypass rewiring and robustness of complex networks

    NASA Astrophysics Data System (ADS)

    Park, Junsang; Hahn, Sang Geun

    2016-08-01

    A concept of bypass rewiring is introduced, and random bypass rewiring is analytically and numerically investigated with simulations. Our results show that bypass rewiring makes networks robust against removal of nodes including random failures and attacks. In particular, random bypass rewiring connects all nodes except the removed nodes on an even degree infinite network and makes the percolation threshold 0 for arbitrary occupation probabilities. In our example, the even degree network is more robust than the original network with random bypass rewiring, while the original network is more robust than the even degree networks without random bypass. We propose a greedy bypass rewiring algorithm which guarantees the maximum size of the largest component at each step, assuming which node will be removed next is unknown. The simulation result shows that the greedy bypass rewiring algorithm improves the robustness of the autonomous system of the Internet under attacks more than random bypass rewiring.

  7. Further development of a method for computing three-dimensional subsonic viscous flows in turbofan lobe mixers

    NASA Technical Reports Server (NTRS)

    Lin, S. J.; Kreskovsky, J. P.; Briley, W. R.; Mcdonald, H.

    1983-01-01

    Procedure for computing subsonic, turbulent flow in turbofan lobe mixers was extended to allow consideration of flow fields in which a swirl component of velocity may be present. Additional, an optional k-lambda turbulence model was added to the procedure. The method of specifying the initial flow field was also modified, allowing parametric specification or radial secondary flow velocities, and making it possible to consider initial flow fields which have significant inlet secondary flow vorticity. A series of example calculations was performed which demonstrate the various capabilities of the modified code. These calculations demonstrate the effects of initial secondary flows of various magnitudes, the effects of swirl, and the effects of turbulence model on the mixing process. The results of these calculations indicate that the initial secondary flows, presumed to be generated within the lobes, play a dominant role in the mixing process, and that the predicted results are relatively insensitive to the turbulence model used.

  8. Spatial correlation in the ambient core noise field of a turbofan engine.

    PubMed

    Miles, Jeffrey Hilton

    2012-06-01

    An acoustic transfer function relating combustion noise and turbine exit noise in the presence of enclosed ambient core noise is investigated using a dynamic system model and an acoustic system model for the particular turbofan engine studied and for a range of operating conditions. Measurements of cross-spectra magnitude and phase between the combustor and turbine exit and auto-spectra at the turbine exit and combustor are used to show the presence of indirect and direct combustion noise over the frequency range of 0-400 Hz. The procedure used evaluates the ratio of direct to indirect combustion noise. The procedure used also evaluates the post-combustion residence time in the combustor which is a factor in the formation of thermal NO(x) and soot in this region. These measurements are masked by the ambient core noise sound field in this frequency range which is observable since the transducers are situated within an acoustic wavelength of one another. An ambient core noise field model based on one and two dimensional spatial correlation functions is used to replicate the spatially correlated response of the pair of transducers. The spatial correlation function increases measured attenuation due to destructive interference and masks the true attenuation of the turbine.

  9. Spatial Correlation in the Ambient Core Noise Field of a Turbofan Engine

    NASA Technical Reports Server (NTRS)

    Miles, Jeffrey Hilton

    2012-01-01

    An acoustic transfer function relating combustion noise and turbine exit noise in the presence of enclosed ambient core noise is investigated using a dynamic system model and an acoustic system model for the particular turbofan engine studied and for a range of operating conditions. Measurements of cross-spectra magnitude and phase between the combustor and turbine exit and auto-spectra at the turbine exit and combustor are used to show the presence of indirect and direct combustion noise over the frequency range of 0 400 Hz. The procedure used evaluates the ratio of direct to indirect combustion noise. The procedure used also evaluates the post-combustion residence time in the combustor which is a factor in the formation of thermal NOx and soot in this region. These measurements are masked by the ambient core noise sound field in this frequency range which is observable since the transducers are situated within an acoustic wavelength of one another. An ambient core noise field model based on one and two dimensional spatial correlation functions is used to replicate the spatially correlated response of the pair of transducers. The spatial correlation function increases measured attenuation due to destructive interference and masks the true attenuation of the turbine.

  10. Scale model performance test investigation of mixed flow exhaust systems for an energy efficient engine /E3/ propulsion system

    NASA Technical Reports Server (NTRS)

    Kuchar, A. P.; Chamberlin, R.

    1983-01-01

    As part of the NASA Energy Efficient Engine program, scale-model performance tests of a mixed flow exhaust system were conducted. The tests were used to evaluate the performance of exhaust system mixers for high-bypass, mixed-flow turbofan engines. The tests indicated that: (1) mixer penetration has the most significant affect on both mixing effectiveness and mixer pressure loss; (2) mixing/tailpipe length improves mixing effectiveness; (3) gap reduction between the mixer and centerbody increases high mixing effectiveness; (4) mixer cross-sectional shape influences mixing effectiveness; (5) lobe number affects mixing degree; and (6) mixer aerodynamic pressure losses are a function of secondary flows inherent to the lobed mixer concept.

  11. 75 FR 50945 - Airworthiness Directives; Pratt & Whitney JT8D-209, -217, -217A, -217C, and -219 Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-18

    ... JT8D-209, -217, -217A, -217C, and -219 Turbofan Engines AGENCY: Federal Aviation Administration (FAA... airworthiness directive (AD) for Pratt & Whitney (PW) JT8D-209, -217, -217A, -217C, and -219 turbofan engines. That AD currently requires revisions to the engine manufacturer's time limits section (TLS) to...

  12. 75 FR 51657 - Airworthiness Directives; Pratt & Whitney Canada Corp. (P&WC) PW615F-A Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-23

    ...-06] RIN 2120-AA64 Airworthiness Directives; Pratt & Whitney Canada Corp. (P&WC) PW615F-A Turbofan... adding the following new AD: 2010-17-06 Pratt & Whitney Canada Corp. (formerly Pratt & Whitney Canada.... Applicability (c) This AD applies to Pratt & Whitney Canada Corp. PW615F-A turbofan engines with fuel/oil...

  13. 76 FR 70382 - Airworthiness Directives; General Electric Company (GE) CF6-80C2B Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-14

    ... Federal Aviation Administration 14 CFR Part 39 RIN 2120-AA64 Airworthiness Directives; General Electric Company (GE) CF6-80C2B Series Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION... directive (AD) that applies to all GE CF6-80C2B series turbofan engines. The existing AD currently...

  14. 76 FR 292 - Airworthiness Directives; General Electric Company CF6-45 and CF6-50 Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-04

    ... directive (AD) that applies to General Electric Company (GE) CF6-45 and CF6-50 series turbofan engines. The... Federal Aviation Administration 14 CFR Part 39 RIN 2120-AA64 Airworthiness Directives; General Electric Company CF6-45 and CF6-50 Series Turbofan Engines AGENCY: Federal Aviation Administration (FAA),...

  15. Results of an Advanced Fan Stage Operating Over a Wide Range of Speed and Bypass Ratio. Part 1; Fan Stage Design and Experimental Results

    NASA Technical Reports Server (NTRS)

    Suder, Kenneth L.; Prahst, Patricia S.; Thorp, Scott A.

    2011-01-01

    NASA s Fundamental Aeronautics Program is investigating turbine-based combined cycle (TBCC) propulsion systems for access to space because it provides the potential for aircraft-like, space-launch operations that may significantly reduce launch costs and improve safety. To this end, National Aeronautics and Space Administration (NASA) and General Electric (GE) teamed to design a Mach 4 variable cycle turbofan/ramjet engine for access to space. To enable the wide operating range of a Mach 4+ variable cycle turbofan ramjet required the development of a unique fan stage design capable of multi-point operation to accommodate variations in bypass ratio (10 ), fan speed (7 ), inlet mass flow (3.5 ), inlet pressure (8 ), and inlet temperature (3 ). In this paper, NASA has set out to characterize a TBCC engine fan stage aerodynamic performance and stability limits over a wide operating range including power-on and hypersonic-unique "windmill" operation. Herein, we will present the fan stage design, and the experimental test results of the fan stage operating from 15 to 100 percent corrected design speed. Whereas, in the companion paper, we will provide an assessment of NASA s APNASA code s ability to predict the fan stage performance and operability over a wide range of speed and bypass ratio.

  16. A Comparison of Multivariable Control Design Techniques for a Turbofan Engine Control

    NASA Technical Reports Server (NTRS)

    Garg, Sanjay; Watts, Stephen R.

    1995-01-01

    This paper compares two previously published design procedures for two different multivariable control design techniques for application to a linear engine model of a jet engine. The two multivariable control design techniques compared were the Linear Quadratic Gaussian with Loop Transfer Recovery (LQG/LTR) and the H-Infinity synthesis. The two control design techniques were used with specific previously published design procedures to synthesize controls which would provide equivalent closed loop frequency response for the primary control loops while assuring adequate loop decoupling. The resulting controllers were then reduced in order to minimize the programming and data storage requirements for a typical implementation. The reduced order linear controllers designed by each method were combined with the linear model of an advanced turbofan engine and the system performance was evaluated for the continuous linear system. Included in the performance analysis are the resulting frequency and transient responses as well as actuator usage and rate capability for each design method. The controls were also analyzed for robustness with respect to structured uncertainties in the unmodeled system dynamics. The two controls were then compared for performance capability and hardware implementation issues.

  17. Effect on fuel efficiency of parameter variations in the cost function for multivariable control of a turbofan engine. Master's thesis

    SciTech Connect

    Dougherty, B.L.

    1981-09-01

    In modern turbofan engines, variable geometry has been incorporated to improve some off-design performance. Most control designs ignore this variable geometry and use fuel metering as the primary control input. This thesis investigates the use of variable geometry to control the engine and, thereby, reduce fuel consumption due to transients. Additionally, steady-state trim conditions are altered to reduce the static fuel consumption. The non-linear transient simualtion program is used to analyze the steady-state operating condition and develop small perturbation control limitations. Linear models, both large and reduced order, are used in analyzing the effect of controllers on system response. A computer program was generated to reduce a large order linear model to a usable size for control system development. This analysis shows the reduced-order regime dependent controllers to be viable and to favorably enhance the quest for reducing specific fuel consumption in existing engines.

  18. Carotid bypass for carotid occlusion.

    PubMed

    Hage, Ziad A; Behbahani, Mandana; Amin-Hanjani, Sepideh; Charbel, Fady T

    2015-07-01

    The 2-year risk of ipsilateral ischemic stroke following internal carotid artery occlusion (ICAO) in a patient undergoing maximal medical therapy is 5-8% per year. While medical therapy may reduce the risk of stroke, it does not completely eliminate it. Since the 1985 extracranial-intracranial (EC-IC) bypass study, additional trials have been conducted to further investigate the usefulness of EC-IC bypass surgery in more selected patients with cerebral ischemia and impaired hemodynamic reserve. These important studies will be briefly reviewed in this article, as well as a discussion regarding the utility of bypass surgery for ICAO in current clinical practice. In addition, a short discussion regarding the pathophysiology of carotid occlusion will be presented. We will also highlight our own institutional patient selection criteria based on the latest methods for hemodynamic assessment, as well as our intraoperative flow assisted surgical techniques (FAST), and post-operative patient follow-up.

  19. Acoustic Detection of Faults and Degradation in a High-Bypass Turbofan Engine during VIPR Phase III Testing

    NASA Technical Reports Server (NTRS)

    Boyle, Devin K.

    2017-01-01

    The Vehicle Integrated Propulsion Research (VIPR) Phase III project was executed at Edwards Air Force Base, California, by the National Aeronautics and Space Administration and several industry, academic, and government partners in the summer of 2015. One of the research objectives was to use external radial acoustic microphone arrays to detect changes in the noise characteristics produced by the research engine during volcanic ash ingestion and seeded fault insertion scenarios involving bleed air valves. Preliminary results indicate the successful acoustic detection of suspected degradation as a result of cumulative exposure to volcanic ash. This detection is shown through progressive changes, particularly in the high-frequency content, as a function of exposure to greater cumulative quantities of ash. Additionally, detection of the simulated failure of the 14th stage stability bleed valve and, to a lesser extent, the station 2.5 stability bleed valve, to their fully-open fail-safe positions was achieved by means of spectral comparisons between nominal (normal valve operation) and seeded fault scenarios.

  20. Secondary and College LD Bypass Strategies.

    ERIC Educational Resources Information Center

    Mosby, Robert J.

    1981-01-01

    The author describes the Developmental By-Pass (DBP) Instructional technology for teaching secondary and college learning disabled (LD) students by allowing students to bypass ordering and organizational deficits. (SB)

  1. 40 CFR 403.17 - Bypass.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... loss of natural resources which can reasonably be expected to occur in the absence of a bypass. Severe... essential maintenance to assure efficient operation. These bypasses are not subject to the provision...

  2. Types of Coronary Artery Bypass Grafting

    MedlinePlus

    ... from the NHLBI on Twitter. Types of Coronary Artery Bypass Grafting There are several types of coronary ... for you based on your needs. Traditional Coronary Artery Bypass Grafting Traditional CABG is used when at ...

  3. Who Needs Coronary Artery Bypass Grafting?

    MedlinePlus

    ... from the NHLBI on Twitter. Who Needs Coronary Artery Bypass Grafting? Coronary artery bypass grafting (CABG) is used to treat people ... or after a heart attack to treat blocked arteries. Your doctor may recommend CABG if other treatments, ...

  4. Coronary Artery Disease: Angioplasty or Bypass Surgery?

    MedlinePlus

    Coronary artery disease: Angioplasty or bypass surgery? I'm getting a cardiac catheterization. If blockages are found, ... angioplasty or bypass surgery? Answers from Rekha Mankad, M.D. During cardiac catheterization, your doctor will examine ...

  5. Psychological Effects of Intestinal Bypass Surgery.

    ERIC Educational Resources Information Center

    Wampler, Richard S.; And Others

    1980-01-01

    Preoperative and postoperative intestinal bypass patients were evaluated. Results suggest that postoperative bypass patients have improved psychological health and an increased sense of freedom and well-being but may need assistance in improving self-concepts. (Author)

  6. System for Centering a Turbofan in a Nacelle During Tests

    NASA Technical Reports Server (NTRS)

    Cunningham, Cameron C.; Thompson, William K.; Hughes, Christopher E.; Shook, Tony D.

    2003-01-01

    A feedback position-control system has been developed for maintaining the concentricity of a turbofan with respect to a nacelle during acoustic and flow tests in a wind tunnel. The system is needed for the following reasons: Thermal and thrust loads can displace the fan relative to the nacelle; In the particular test apparatus (see Figure 1), denoted as a rotor-only nacelle (RAN), the struts, vanes, and other stator components of a turbofan engine that ordinarily maintain the required concentricity in the face of thermal and thrust loads are not present; and The struts and stator components are not present because it is necessary to provide a flow path that is acoustically clean in the sense that the measured noise can be attributed to the fan alone. The system is depicted schematically in Figure 2. The nacelle is supported by two struts attached to a two-axis traverse table located outside the wind-tunnel wall. Two servomotors acting through 100:1 gearboxes drive the table along the Y and Z axes, which are perpendicular to the axis of rotation. The Y and Z components of the deviation from concentricity are measured by four laser displacement sensors mounted on the nacelle and aimed at reflective targets on the center body, which is part of the fan assembly. The outputs of the laser displacement sensors are digitized and processed through a personal computer programmed with control software. The control output of the computer commands the servomotors to move the table as needed to restore concentricity. Numerous software and hardware travel limits and alarms are provided to maximize safety. A highly ablative rub strip in the nacelle minimizes the probability of damage in the event that a deviation from concentricity exceeds the radial clearance [<0.004 in. (<0.1 mm)] between the inner surface of the nacelle and the tips of the fan blades. To be able to prevent an excursion in excess of the tip clearance, the system must be accurate enough to control X and Y

  7. Acoustic scattering by an axially-segmented turbofan inlet duct liner at supersonic fan speeds

    NASA Astrophysics Data System (ADS)

    McAlpine, A.; Astley, R. J.; Hii, V. J. T.; Baker, N. J.; Kempton, A. J.

    2006-07-01

    Fan noise is one of the principal noise sources in turbofan aero-engines. At supersonic fan speeds, fan tones are generated by the "rotor-alone" pressure field. In general, these tones can be well absorbed by an inlet duct acoustic liner, except at high supersonic fan speeds when the rotor-alone pressure field is well cut-on. In this article an axially segmented liner is proposed, which is predicted to improve the attenuation of tones at high supersonic fan speeds. The analysis is based on locally reacting cavity liners. The axially segmented liner is axisymmetric and consists of two circular sections of different linings joined together. The optimum design consists of two linings with the same face-sheet resistance, but with different cavity depths. The depth of the liner adjacent to the fan is very thin. This means that where the two liners are joined there is a wall impedance discontinuity that can cause acoustic scattering. Fan tones can be modelled in terms of spinning modes in a uniform circular-section duct. The liner is axisymmetric, so modal scattering will be only between different radial modes. The optimum design minimizes the acoustic energy scattered into the first radial mode. This improves the attenuation of fan tones at high supersonic fan speeds, because acoustic energy is scattered into high radial mode orders, which are better absorbed by the lining.

  8. Turbofan forced mixer-nozzle internal flowfield. Volume 3: A computer code for 3-D mixing in axisymmetric nozzles

    NASA Technical Reports Server (NTRS)

    Kreskovsky, J. P.; Briley, W. R.; Mcdonald, H.

    1982-01-01

    A finite difference method is developed for making detailed predictions of three dimensional subsonic turbulent flow in turbofan lobe mixers. The governing equations are solved by a forward-marching solution procedure which corrects an inviscid potential flow solution for viscous and thermal effects, secondary flows, total pressure distortion and losses, internal flow blockage and pressure drop. Test calculations for a turbulent coaxial jet flow verify that the turbulence model performs satisfactorily for this relatively simple flow. Lobe mixer flows are presented for two geometries typical of current mixer design. These calculations included both hot and cold flow conditions, and both matched and mismatched Mach number and total pressure in the fan and turbine streams.

  9. An analytical study on the performance of the organic Rankine cycle for turbofan engine exhaust heat recovery

    NASA Astrophysics Data System (ADS)

    Saadon, S.; Abu Talib, A. R.

    2016-10-01

    Due to energy shortage and global warming, issues of energy saving have become more important. To increase the energy efficiency and reduce the fuel consumption, waste heat recovery is a significant method for energy saving. The organic Rankine cycle (ORC) has great potential to recover the waste heat from the core jet exhaust of a turbofan engine and use it to produce power. Preliminary study of the design concept and thermodynamic performance of this ORC system would assist researchers to predict the benefits of using the ORC system to extract the exhaust heat engine. In addition, a mathematical model of the heat transfer of this ORC system is studied and developed. The results show that with the increment of exhaust heat temperature, the mass flow rate of the working fluid, net power output and the system thermal efficiency will also increase. Consequently, total consumption of jet fuel could be significantly saved as well.

  10. An Overview of the NASA Fundamental Aeronautics Program Subsonic Fixed Wing Project and Ultra High Bypass Partnership Research Goals

    NASA Technical Reports Server (NTRS)

    Hughes, Christopher E.

    2009-01-01

    An overview of the NASA Fundamental Aeronautics Program (FAP) mission and goals is presented. One of the subprograms under the FAP, the Subsonic Fixed Wing Project (SFW), is the focus of the presentation. The SFW system environmental metrics are discussed, along with highlights of planned, systematic approach to research to reduce the environmental impact of commercial aircraft in the areas of acoustics, fuel burn and emissions. The presentation then focuses on collaborative research being conducted with U.S. Industry on the Ultra High Bypass (UHB) engine cycle, the propulsion cycle selected by the SFW to meet the system goals. The partnerships with General Electric Aviation to investigate Open Rotor propulsion concepts and with Pratt & Whitney to investigate the Geared Turbofan UHB engine are highlighted, including current and planned future collaborative research activities with NASA and each organization.

  11. Heart bypass surgery - minimally invasive

    MedlinePlus

    ... MIDCAB; Robot-assisted coronary artery bypass; RACAB; Keyhole heart surgery; CAD - MIDCAB; Coronary artery disease - MIDCAB ... To perform this surgery: The heart surgeon will make a 3- to 5-inch (8 to 13 centimeters) surgical cut in the left part of your chest ...

  12. Interventions in Infrainguinal Bypass Grafts

    SciTech Connect

    Mueller-Huelsbeck, S. Order, B.-M.; Jahnke, T.

    2006-02-15

    The interventional radiologist plays an important role in the detection and prevention of infrainguinal bypass failure. Early detection and evaluation of flow-limiting lesions effectively preserve graft (venous bypass and polyester or expanded polytetrafluoroethylene bypass) patency by identifying stenoses before occlusion occurs. Delay in treatment of the at-risk graft may result in graft failure and a reduced chance of successful revascularization. For this reason, surveillance protocols form an important part of follow-up after infrainguinal bypass surgery. As well as having an understanding of the application of imaging techniques including ultrasound, MR angiography, CT angiography and digital subtraction angiography, the interventional radiologist should have detailed knowledge of the minimally invasive therapeutic options. Percutaneous transluminal angioplasty (PTA), or alternatively cutting balloon angioplasty, is the interventional treatment of choice in prevention of graft failure and occlusion. Further alternatives include metallic stent placement, fibrinolysis, and mechanical thrombectomy. Primary assisted patency rates following PTA can be up to 65% at 5 years. When the endovascular approach is unsuccessful, these therapeutic options are complemented by surgical procedures including vein patch revision, jump grafting, or placement of a new graft.

  13. Spectral Separation of the Turbofan Engine Coherent Combustion Noise Component

    NASA Technical Reports Server (NTRS)

    Miles, Jeffrey Hilton

    2008-01-01

    The core noise components of a dual spool turbofan engine (Honeywell TECH977) were separated by the use of a coherence function. A source location technique based on adjusting the time delay between the combustor pressure sensor signal and the far-field microphone signal to maximize the coherence and remove as much variation of the phase angle with frequency as possible was used. While adjusting the time delay to maximize the coherence and minimize the cross spectrum phase angle variation with frequency, the discovery was made that for the 130 microphone a 90.027 ms time shift worked best for the frequency band from 0 to 200 Hz while a 86.975 ms time shift worked best for the frequency band from 200 to 400 Hz. Since the 0 to 200 Hz band signal took more time to travel the same distance, it is slower than the 200 to 400 Hz band signal. This suggests the 0 to 200 Hz coherent cross spectral density band is partly due to indirect combustion noise attributed to hot spots interacting with the turbine. The signal in the 200 to 400 Hz frequency band is attributed mostly to direct combustion noise.

  14. Active control of fan noise from a turbofan engine

    NASA Technical Reports Server (NTRS)

    Thomas, Russell H.; Burdisso, Ricardo A.; Fuller, Christopher R.; O'Brien, Walter F.

    1994-01-01

    A three-channel active control system is applied to an operational turbofan engine to reduce tonal noise produced by both the fan and the high-pressure compressor. The control approach is the feedforward filtered-x least-mean-square algorithm implemented on a digital signal processing board. Reference transducers mounted on the engine case provide blade passing and harmonics frequency information to the controller. Error information is provided by large area microphones placed in the acoustic far field. To minimize the error signal, the controller actuates loudspeakers mounted on the inlet to produce destructive interference. The sound pressure level of the fundamental tone of the fan was reduced using the three-channel controller by up to 16 dB over a +/- 30-deg angle about the engine axis. A single-channel controller could produce reduction over a +/- 15-deg angle. The experimental results show the control to be robust. Outside of the areas contolled, the levels of the tone actually increased due to the generation of radial modes by the control sources. Simultaneous control of two tones is achieved with parallel controllers. The fundamental and the first harmonic tones of the fan were controlled simultaneously with reductions of 12 and 5 dBA, respectively, measured on the engine axis. Simultaneous control was also demonstrated for the fan fundamental and the high-pressure compressor fundamental tones.

  15. Active control of fan noise from a turbofan engine

    NASA Technical Reports Server (NTRS)

    Thomas, Russell H.; Burdisso, Ricardo A.; Fuller, Christopher R.; O'Brien, Walter F.

    1993-01-01

    A three channel active control system is applied to an operational turbofan engine in order to reduce tonal noise produced by both the fan and high pressure compressor. The control approach is the feedforward filtered-x least-mean-square algorithm implemented on a digital signal processing board. Reference transducers mounted on the engine case provides blade passing and harmonics frequency information to the controller. Error information is provided by large area microphones placed in the acoustic far field. In order to minimize the error signal, the controller actuates loudspeakers mounted on the inlet to produce destructive interference. The sound pressure level of the fundamental tone of the fan was reduced using the three channel controller by up to 16 dB over a 60 deg angle about the engine axis. A single channel controller could produce reduction over a 30 deg angle. The experimental results show the control to be robust. Simultaneous control of two tones is done with parallel controllers. The fundamental and the first harmonic tones of the fan were controlled simultaneously with reductions of 12 dBA and 5 dBA, respectively, measured on the engine axis. Simultaneous control was also demonstrated for the fan fundamental and the high pressure compressor fundamental tones.

  16. Kalman Filter Constraint Tuning for Turbofan Engine Health Estimation

    NASA Technical Reports Server (NTRS)

    Simon, Dan; Simon, Donald L.

    2005-01-01

    Kalman filters are often used to estimate the state variables of a dynamic system. However, in the application of Kalman filters some known signal information is often either ignored or dealt with heuristically. For instance, state variable constraints are often neglected because they do not fit easily into the structure of the Kalman filter. Recently published work has shown a new method for incorporating state variable inequality constraints in the Kalman filter, which has been shown to generally improve the filter s estimation accuracy. However, the incorporation of inequality constraints poses some risk to the estimation accuracy as the Kalman filter is theoretically optimal. This paper proposes a way to tune the filter constraints so that the state estimates follow the unconstrained (theoretically optimal) filter when the confidence in the unconstrained filter is high. When confidence in the unconstrained filter is not so high, then we use our heuristic knowledge to constrain the state estimates. The confidence measure is based on the agreement of measurement residuals with their theoretical values. The algorithm is demonstrated on a linearized simulation of a turbofan engine to estimate engine health.

  17. Study of small turbofan engines applicable to single-engine light airplanes

    NASA Technical Reports Server (NTRS)

    Merrill, G. L.

    1976-01-01

    The design, efficiency and cost factors are investigated for application of turbofan propulsion engines to single engine, general aviation light airplanes. A companion study of a hypothetical engine family of a thrust range suitable to such aircraft and having a high degree of commonality of design features and parts is presented. Future turbofan powered light airplanes can have a lower fuel consumption, lower weight, reduced airframe maintenance requirements and improved engine overhaul periods as compared to current piston engined powered airplanes. Achievement of compliance with noise and chemical emission regulations is expected without impairing performance, operating cost or safety.

  18. Full 3D Analysis of the GE90 Turbofan Primary Flowpath

    NASA Technical Reports Server (NTRS)

    Turner, Mark G.

    2000-01-01

    The multistage simulations of the GE90 turbofan primary flowpath components have been performed. The multistage CFD code, APNASA, has been used to analyze the fan, fan OGV and booster, the 10-stage high-pressure compressor and the entire turbine system of the GE90 turbofan engine. The code has two levels of parallel, and for the 18 blade row full turbine simulation has 87.3 percent parallel efficiency with 121 processors on an SGI ORIGIN. Grid generation is accomplished with the multistage Average Passage Grid Generator, APG. Results for each component are shown which compare favorably with test data.

  19. A program for calculating turbofan-driven lift-fan propulsion system performance

    NASA Technical Reports Server (NTRS)

    Tauber, M. E.; Fuhs, A. E.; Paterson, J. A.

    1976-01-01

    The performance of a turbofan-powered lift fan propulsion system for vertical takeoff and landing (VTOL) aircraft is calculated. The program formulation consists of taking bleed air from a turbofan engine, heating the bleed air in an interburner, and passing it through a tip turbine to drive a lift fan. Two options are available: bleed air from the engine exhaust, or bleed air that has passed through the engine fan only. This computer program will benefit persons unfamiliar with the thermodynamics of engine cycle analysis.

  20. Natural Product Screening Reveals Naphthoquinone Complex I Bypass Factors

    PubMed Central

    Mevers, Emily; Higgins, Kathleen W.; Fomina, Yevgenia; Zhang, Jianming; Mandinova, Anna; Newman, David; Shaw, Stanley Y.; Clardy, Jon; Mootha, Vamsi K.

    2016-01-01

    Deficiency of mitochondrial complex I is encountered in both rare and common diseases, but we have limited therapeutic options to treat this lesion to the oxidative phosphorylation system (OXPHOS). Idebenone and menadione are redox-active molecules capable of rescuing OXPHOS activity by engaging complex I-independent pathways of entry, often referred to as “complex I bypass.” In the present study, we created a cellular model of complex I deficiency by using CRISPR genome editing to knock out Ndufa9 in mouse myoblasts, and utilized this cell line to develop a high-throughput screening platform for novel complex I bypass factors. We screened a library of ~40,000 natural product extracts and performed bioassay-guided fractionation on a subset of the top scoring hits. We isolated four plant-derived 1,4-naphthoquinone complex I bypass factors with structural similarity to menadione: chimaphilin and 3-chloro-chimaphilin from Chimaphila umbellata and dehydro-α-lapachone and dehydroiso-α-lapachone from Stereospermum euphoroides. We also tested a small number of structurally related naphthoquinones from commercial sources and identified two additional compounds with complex I bypass activity: 2-methoxy-1,4-naphthoquinone and 2-methoxy-3-methyl-1,4,-naphthoquinone. The six novel complex I bypass factors reported here expand this class of molecules and will be useful as tool compounds for investigating complex I disease biology. PMID:27622560

  1. Natural Product Screening Reveals Naphthoquinone Complex I Bypass Factors.

    PubMed

    Vafai, Scott B; Mevers, Emily; Higgins, Kathleen W; Fomina, Yevgenia; Zhang, Jianming; Mandinova, Anna; Newman, David; Shaw, Stanley Y; Clardy, Jon; Mootha, Vamsi K

    2016-01-01

    Deficiency of mitochondrial complex I is encountered in both rare and common diseases, but we have limited therapeutic options to treat this lesion to the oxidative phosphorylation system (OXPHOS). Idebenone and menadione are redox-active molecules capable of rescuing OXPHOS activity by engaging complex I-independent pathways of entry, often referred to as "complex I bypass." In the present study, we created a cellular model of complex I deficiency by using CRISPR genome editing to knock out Ndufa9 in mouse myoblasts, and utilized this cell line to develop a high-throughput screening platform for novel complex I bypass factors. We screened a library of ~40,000 natural product extracts and performed bioassay-guided fractionation on a subset of the top scoring hits. We isolated four plant-derived 1,4-naphthoquinone complex I bypass factors with structural similarity to menadione: chimaphilin and 3-chloro-chimaphilin from Chimaphila umbellata and dehydro-α-lapachone and dehydroiso-α-lapachone from Stereospermum euphoroides. We also tested a small number of structurally related naphthoquinones from commercial sources and identified two additional compounds with complex I bypass activity: 2-methoxy-1,4-naphthoquinone and 2-methoxy-3-methyl-1,4,-naphthoquinone. The six novel complex I bypass factors reported here expand this class of molecules and will be useful as tool compounds for investigating complex I disease biology.

  2. The altered expression profile of microRNAs in cardiopulmonary bypass canine models and the effects of mir-499 on myocardial ischemic reperfusion injury

    PubMed Central

    2013-01-01

    Background MicroRNAs were enrolled in various cardiovascular disease especially ischemic heart diseases, but the microRNA changes during myocardial ischemia reperfusion injury underwent cardiopulmonary bypass are still unknown. This study screens the microRNA differences in CPB canines and evaluates the relationship of microRNAs with myocardial ischemia reperfusion injury. Methods 13 healthy canines received CPB with 60 minutes of aortic clamping and cardioplegic arrest, followed by 90 minutes reperfusion. Left ventricular myocardial samples, blood samples and hemodynamic data were taken at different time points. We performed microRNAs microarray experiments upon the left ventricle myocardium tissue of canines before CPB and after reperfusion for 90 minutes by pooling 3 tissue samples together and used qRT-PCR for confirmation. Results Statistically significant difference was found in mir-499 level before CPB and after reperfusion (T1 vs. T4, p = 0.041). We further examined the mir-499 levels by using qRT-PCR in all 13 canines at 4 different time points (T1 vs. T4, p = 0.029). Mir-499 expression was negatively correlated with cardiac troponin T (cTnT) and creatine kinase- MB (CK-MB) levels of canines in all time points samples (r = 0.469, p < 0.001 and r = 0.273, p = 0.050 respectively). Moreover, higher mir-499 expression level was associated with higher dP/dtmax at 25 minutes and 90 minutes after reperfusion. Conclusion Myocardial ischemic reperfusion injury with cardiopulmonary bypass results in declining level of mir-499 expression in left ventricle myocardium of canines, suggesting mir-499 would be a potential therapeutic target in cardiac protection during open heart surgery. PMID:23800236

  3. Model Engine Performance Measurement From Force Balance Instrumentation

    NASA Technical Reports Server (NTRS)

    Jeracki, Robert J.

    1998-01-01

    A large scale model representative of a low-noise, high bypass ratio turbofan engine was tested for acoustics and performance in the NASA Lewis 9- by 15-Foot Low-Speed Wind Tunnel. This test was part of NASA's continuing Advanced Subsonic Technology Noise Reduction Program. The low tip speed fan, nacelle, and an un-powered core passage (with core inlet guide vanes) were simulated. The fan blades and hub are mounted on a rotating thrust and torque balance. The nacelle, bypass duct stators, and core passage are attached to a six component force balance. The two balance forces, when corrected for internal pressure tares, measure the total thrust-minus-drag of the engine simulator. Corrected for scaling and other effects, it is basically the same force that the engine supports would feel, operating at similar conditions. A control volume is shown and discussed, identifying the various force components of the engine simulator thrust and definitions of net thrust. Several wind tunnel runs with nearly the same hardware installed are compared, to identify the repeatability of the measured thrust-minus-drag. Other wind tunnel runs, with hardware changes that affected fan performance, are compared to the baseline configuration, and the thrust and torque effects are shown. Finally, a thrust comparison between the force balance and nozzle gross thrust methods is shown, and both yield very similar results.

  4. Analytical and computational investigations of a magnetohydrodynamics (MHD) energy-bypass system for supersonic gas turbine engines to enable hypersonic flight

    NASA Astrophysics Data System (ADS)

    Benyo, Theresa Louise

    Historically, the National Aeronautics and Space Administration (NASA) has used rocket-powered vehicles as launch vehicles for access to space. A familiar example is the Space Shuttle launch system. These vehicles carry both fuel and oxidizer onboard. If an external oxidizer (such as the Earth's atmosphere) is utilized, the need to carry an onboard oxidizer is eliminated, and future launch vehicles could carry a larger payload into orbit at a fraction of the total fuel expenditure. For this reason, NASA is currently researching the use of air-breathing engines to power the first stage of two-stage-to-orbit hypersonic launch systems. Removing the need to carry an onboard oxidizer leads also to reductions in total vehicle weight at liftoff. This in turn reduces the total mass of propellant required, and thus decreases the cost of carrying a specific payload into orbit or beyond. However, achieving hypersonic flight with air-breathing jet engines has several technical challenges. These challenges, such as the mode transition from supersonic to hypersonic engine operation, are under study in NASA's Fundamental Aeronautics Program. One propulsion concept that is being explored is a magnetohydrodynamic (MHD) energy- bypass generator coupled with an off-the-shelf turbojet/turbofan. It is anticipated that this engine will be capable of operation from takeoff to Mach 7 in a single flowpath without mode transition. The MHD energy bypass consists of an MHD generator placed directly upstream of the engine, and converts a portion of the enthalpy of the inlet flow through the engine into electrical current. This reduction in flow enthalpy corresponds to a reduced Mach number at the turbojet inlet so that the engine stays within its design constraints. Furthermore, the generated electrical current may then be used to power aircraft systems or an MHD accelerator positioned downstream of the turbojet. The MHD accelerator operates in reverse of the MHD generator, re-accelerating the

  5. Mini cardiopulmonary bypass: Anesthetic considerations

    PubMed Central

    Alsatli, Raed A.

    2012-01-01

    This review article is going to elaborate on the description, components, and advantages of mini-cardiopulmonary bypass (mini-CPB), with special reference to the anesthetic management and fast track anesthesia with mini-CPB. There are several clinical advantages of mini-CPB like, reduced inflammatory reaction to the pump, reduced need for allogenic blood transfusion and lower incidence of postoperative neurological complications. There are certainly important points that have to be considered by anesthesiologists to avoid sever perturbation in the cardiac output and blood pressure during mini-CPB. Fast-track anesthesia provides advantages regarding fast postoperative recovery from anesthesia, and reduction of postoperative ventilation time. Mini bypass offers a sound alternative to conventional CPB, and has definite advantages. It has its limitations, but even with that it has a definite place in the current practice of cardiac surgery. PMID:25885494

  6. 78 FR 71532 - Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co KG Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-29

    ... Deutschland Ltd & Co KG Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ] ACTION: Notice... Deutschland Ltd & Co KG, Eschenweg 11, D-15827 Blankenfelde-Mahlow, Germany; phone: 49 0 33 7086 1200; fax: 49... & Co KG: Docket No. FAA-2006-24777; Directorate Identifier 2006-NE-19-AD. (a) Comments Due Date The...

  7. 77 FR 16917 - Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co KG Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-23

    ... Deutschland Ltd & Co KG Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final... information identified in this AD, contact Rolls-Royce Deutschland Ltd & Co KG, Eschenweg 11, Dahlewitz, 15827... Rolls-Royce Deutschland Ltd & Co KG (Formerly Rolls-Royce plc, Derby, England): Amendment...

  8. 78 FR 2195 - Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co KG Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-10

    ...; AD 2012-26-14] RIN 2120-AA64 Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co KG Turbofan.... SUMMARY: We are adopting a new airworthiness directive (AD) for all Rolls-Royce Deutschland Ltd & Co KG... Ltd & Co KG, Eschenweg 11, Dahlewitz, 15827 Blankenfelde- Mahlow, Germany; telephone: 49 0...

  9. 77 FR 20987 - Airworthiness Directives; Rolls-Royce plc Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-09

    ...-Trent 800 series turbofan engines. The last comment response in the preamble and the first sentence of regulatory text paragraph (g)(1) are incorrect. The repetitive inspection interval should be 2,000 flight cycles, not 1,000 flight cycles. This document corrects those errors. In all other respects, the...

  10. 76 FR 64283 - Airworthiness Directives; Rolls-Royce plc (RR) Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-18

    ... currently requires inspecting the intermediate-pressure (IP) compressor rotor shaft rear balance land for... 895-17 turbofan engines. That AD requires a onetime eddy current inspection (ECI) of the rear balance... rear balance land of IP compressor rotor shafts. We issued that AD to detect cracking on the...

  11. 75 FR 51659 - Airworthiness Directives; Pratt & Whitney Canada Corp. PW617F-E Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-23

    ...-01] RIN 2120-AA64 Airworthiness Directives; Pratt & Whitney Canada Corp. PW617F-E Turbofan Engines... & Whitney Canada Corp. issued an Alert Service Bulletin (ASB) No. PW600-72-A66019 to inspect and replace any... power reduction. Pratt & Whitney Canada Corp. issued an ASB No. PW600-72-A66019 to inspect and...

  12. 75 FR 27491 - Airworthiness Directives; Pratt & Whitney Canada Corp. PW617F-E Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-17

    ... Canada Corp. PW617F-E Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice... Metering Unit (FMU), resulting in fuel flow drop and subsequent power reduction. Pratt & Whitney Canada... holidays. Fax: (202) 493-2251. Contact Pratt & Whitney Canada Corp., 1000 Marie-Victorin, Longueuil,...

  13. 75 FR 27489 - Airworthiness Directives; Pratt & Whitney Canada Corp. PW615F-A Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-17

    ... Canada Corp. PW615F-A Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice... Metering Unit (FMU), resulting in fuel flow drop and subsequent power reduction. Pratt & Whitney Canada... Pratt & Whitney Canada Corp. has confirmed similar dormant failure of worn through poppets of...

  14. FJ44 Turbofan Engine Test at NASA Glenn Research Center's Aero-Acoustic Propulsion Laboratory

    NASA Technical Reports Server (NTRS)

    Lauer, Joel T.; McAllister, Joseph; Loew, Raymond A.; Sutliff, Daniel L.; Harley, Thomas C.

    2009-01-01

    A Williams International FJ44-3A 3000-lb thrust class turbofan engine was tested in the NASA Glenn Research Center s Aero-Acoustic Propulsion Laboratory. This report presents the test set-up and documents the test conditions. Farfield directivity, in-duct unsteady pressures, duct mode data, and phased-array data were taken and are reported separately.

  15. 78 FR 61171 - Airworthiness Directives; Rolls-Royce plc Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-03

    ... Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: We are... engines. This AD requires removal of affected parts using a drawdown plan. This AD was prompted by... of the engine and damage to the airplane. DATES: This AD becomes effective November 7, 2013....

  16. 78 FR 17080 - Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co KG Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-20

    ...-29-AD; Amendment 39-17385; AD 2013-05-13] RIN 2120-AA64 Airworthiness Directives; Rolls-Royce... rule. SUMMARY: We are adopting a new airworthiness directive (AD) for certain Rolls-Royce Deutschland Ltd & Co KG (RRD) BR700-710 series turbofan engines. This AD requires replacement of the affected...

  17. 78 FR 68360 - Airworthiness Directives; Rolls-Royce plc Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-14

    ...-01-AD; Amendment 39-17599; AD 2013-19-17] RIN 2120-AA64 Airworthiness Directives; Rolls-Royce plc.... SUMMARY: The FAA is correcting an airworthiness directive (AD) that published in the Federal Register. That AD applies to all Rolls-Royce plc (RR) RB211-535E4-B-37 series turbofan engines. The AD number...

  18. 75 FR 7209 - Airworthiness Directives; Rolls-Royce Corporation (RRC) AE 3007A Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-18

    ...: The FAA proposes to adopt a new airworthiness directive (AD) for RRC AE 3007A series turbofan engines. This proposed AD would require removing or performing initial and repetitive eddy current inspections... wheels for cracks. This proposed AD also reduces the approved life limits of certain HPT stage 2...

  19. 76 FR 68660 - Airworthiness Directives; Pratt & Whitney Division (PW) PW4000 Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-07

    ... Aviation Administration 14 CFR Part 39 [Docket No. FAA-2011-0944; Directorate Identifier 2011-NE-11-AD] RIN... propose to adopt a new airworthiness directive (AD) for PW4000 series turbofan engines. This proposed AD... after the effective date of this proposed AD. This proposed AD was prompted by an engine overspeed...

  20. 78 FR 17297 - Airworthiness Directives; Rolls-Royce plc Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-21

    ...-01-AD; Amendment 39-17390; AD 2013-05-18] RIN 2120-AA64 Airworthiness Directives; Rolls-Royce plc... comments. SUMMARY: We are superseding an existing airworthiness directive (AD) for all Rolls-Royce plc (RR) RB211 Trent 500 series turbofan engines. That AD currently requires a one-time inspection of the...

  1. 76 FR 75735 - Certification of Part 23 Turbofan- and Turbojet-Powered Airplanes and Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-02

    ...This action enhances safety by amending the applicable standards for part 23 turbofan- and turbojet-powered airplanes--which are commonly referred to as ``part 23 jets,'' or ``jets''--as well as turbopropeller-driven and reciprocating-engine airplanes, to reflect the current needs of industry, accommodate future trends, address emerging technologies, and provide for future airplane operations.......

  2. 76 FR 72130 - Airworthiness Directives; Pratt & Whitney JT9D Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-22

    ... revisions to the Airworthiness Limitations Section (ALS) of the manufacturer's Instructions for Continued... life-limited parts. This proposed AD would require additional revisions to the JT9D series engines ALS... all PW JT9D series turbofan engines. That AD requires revisions to the ALS of the manufacturer's...

  3. 76 FR 67591 - Airworthiness Directives; Rolls-Royce Corporation Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-02

    ... Corporation Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule; request for comments. SUMMARY: We are adopting a new airworthiness directive (AD) for Rolls- Royce Corporation... identified in this AD, contact Rolls-Royce Corporation, P.O. Box 420, Indianapolis, IN 46206; phone:...

  4. IgG and complement-mediated tissue damage in the absence of C2: evidence of a functionally active C2-bypass pathway in a guinea pig model.

    PubMed

    Wagner, E; Platt, J L; Howell, D N; Marsh, H C; Frank, M M

    1999-09-15

    In vitro complement-mediated lysis of heavily sensitized sheep erythrocytes by C4-deficient (C4D) guinea pig and C2-deficient (C2D) human sera was demonstrated some years ago. It was postulated that these "complement-bypass" pathways resulted from activation of C1 and components of the alternative pathway. We used normal, C2D, and C4D guinea pigs in a Forssman shock model to test the in vivo relevance of the C2- and C4-bypass pathways of complement activation. High concentrations of both anti-Forssman Ab and C2D or C4D guinea pig serum induced efficient lysis of sheep erythrocytes in vitro. The most efficient lysis was observed when IgG Ab and C2D guinea pig serum were used. Blocking either the classical pathway (treatments with EGTA-Mg2+ or soluble recombinant complement receptor type 1 (sCR1)) or the alternative pathway (treatment with heating at 50 degrees C, sCR1, or soluble recombinant CR1 lacking the first of the four long homologous repeat sequences (sCR1[desLHR-A])) inhibited lysis; both pathways were required for lysis of sheep erythrocytes by C2D and C4D guinea pig sera. i.v. injection of anti-Forssman Ab in normal guinea pigs resulted in rapid death from pulmonary shock, whereas C4D guinea pigs had no adverse effect. Surprisingly, C2D guinea pigs either died in a delayed fashion or had a sublethal reaction. sCR1 treatment prevented Forssman shock in both normal and C2D guinea pigs, whereas sCR1[desLHR-A] prevented Forssman shock only in C2D animals. Our results suggest that the C2-bypass pathway occurs in vivo to produce tissue damage. Activation of complement in the absence of C2 appears to be far more efficient than in the absence of C4.

  5. 76 FR 77107 - Airworthiness Directives; Pratt & Whitney Corp. (PW) JT9D-7R4H1 Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-12

    ... Administration 14 CFR Part 39 [Docket No. FAA-2011-0731; Directorate Identifier 2010-NE-39-AD; Amendment 39-16886; AD 2011-25-10] RIN 2120-AA64 Airworthiness Directives; Pratt & Whitney Corp. (PW) JT9D-7R4H1 Turbofan... new airworthiness directive (AD) for all PW JT9D-7R4H1 turbofan engines. This AD was prompted...

  6. Sea Level Operation Demonstration of F404-GE-400 Turbofan Engine with JP-5/Bio-Fuel Mixture

    DTIC Science & Technology

    2010-03-30

    Aircraft Test and Evaluation Facility Hush House at Naval Air Station Patuxent River, Maryland, on 13 October 2009. The test consisted of two separate...turbofan engine inside the Aircraft Test and Evaluation Facility Hush House at Naval Air Station Patuxent River, Maryland, on 13 October 2009. The test...turbofan engine (ESN 310810) inside the Aircraft Test and Evaluation Facility Hush House at Naval Air Station (NAS) Patuxent River, Maryland, on 13

  7. System Would Detect Foreign-Object Damage in Turbofan Engine

    NASA Technical Reports Server (NTRS)

    Torso, James A.; Litt, Jonathan S.

    2006-01-01

    A proposed data-fusion system, to be implemented mostly in software, would further process the digitized and preprocessed outputs of sensors in a turbofan engine to detect foreign-object damage (FOD) [more precisely, damage caused by impingement of such foreign objects as birds, pieces of ice, and runway debris]. The proposed system could help a flight crew to decide what, if any, response is necessary to complete a flight safely, and could aid mechanics in deciding what post-flight maintenance action might be needed. The sensory information to be utilized by the proposed system would consist of (1) the output of an accelerometer in an engine-vibration-monitoring subsystem and (2) features extracted from a gas path analysis. ["Gas path analysis" (GPA) is a term of art that denotes comprehensive analysis of engine performance derived from readings of fuel-flow meters, shaft-speed sensors, temperature sensors, and the like.] The acceleration signal would first be processed by a wavelet-transform-based algorithm, using a wavelet created for the specific purpose of finding abrupt FOD-induced changes in noisy accelerometer signals. Two additional features extracted would be the amplitude of vibration (determined via a single- frequency Fourier transform calculated at the rotational speed of the engine), and the rate of change in amplitude due to an FOD-induced rotor imbalance. This system would utilize two GPA features: the fan efficiency and the rate of change of fan efficiency with time. The selected GPA and vibrational features would be assessed by two fuzzy-logic inference engines, denoted the "Gas Path Expert" and the "Vibration Expert," respectively (see Figure 1). Each of these inference engines would generate a "possibility" distribution for occurrence of an FOD event: Each inference engine would assign, to its input information, degrees of membership, which would subsequently be transformed into basic probability assignments for the gas path and vibration

  8. History of cardiopulmonary bypass (CPB).

    PubMed

    Hessel, Eugene A

    2015-06-01

    The development of cardiopulmonary bypass (CPB), thereby permitting open-heart surgery, is one of the most important advances in medicine in the 20th century. Many currently practicing cardiac anesthesiologists, cardiac surgeons, and perfusionists are unaware of how recently it came into use (60 years) and how much the practice of CPB has changed during its short existence. In this paper, the development of CPB and the many changes and progress that has taken place over this brief period of time, making it a remarkably safe endeavor, are reviewed. The many as yet unresolved questions are also identified, which sets the stage for the other papers in this issue of this journal.

  9. Outcomes of lower extremity bypass performed for acute limb ischemia

    PubMed Central

    Baril, Donald T.; Patel, Virendra I.; Judelson, Dejah R.; Goodney, Philip P.; McPhee, James T.; Hevelone, Nathanael D.; Cronenwett, Jack L.; Schanzer, Andres

    2013-01-01

    Objective Acute limb ischemia remains one of the most challenging emergencies in vascular surgery. Historically, outcomes following interventions for acute limb ischemia have been associated with high rates of morbidity and mortality. The purpose of this study was to determine contemporary outcomes following lower extremity bypass performed for acute limb ischemia. Methods All patients undergoing infrainguinal lower extremity bypass between 2003 and 2011 within hospitals comprising the Vascular Study Group of New England were identified. Patients were stratified according to whether or not the indication for lower extremity bypass was acute limb ischemia. Primary end points included bypass graft occlusion, major amputation, and mortality at 1 year postoperatively as determined by Kaplan-Meier life table analysis. Multivariable Cox proportional hazards models were constructed to evaluate independent predictors of mortality and major amputation at 1 year. Results Of 5712 lower extremity bypass procedures, 323 (5.7%) were performed for acute limb ischemia. Patients undergoing lower extremity bypass for acute limb ischemia were similar in age (66 vs 67; P = .084) and sex (68% male vs 69% male; P = .617) compared with chronic ischemia patients, but were less likely to be on aspirin (63% vs 75%; P < .0001) or a statin (55% vs 68%; P < .0001). Patients with acute limb ischemia were more likely to be current smokers (49% vs 39%; P < .0001), to have had a prior ipsilateral bypass (33% vs 24%; P = .004) or a prior ipsilateral percutaneous intervention (41% vs 29%; P = .001). Bypasses performed for acute limb ischemia were longer in duration (270 vs 244 minutes; P = .007), had greater blood loss (363 vs 272 mL; P < .0001), and more commonly utilized prosthetic conduits (41% vs 33%; P = .003). Acute limb ischemia patients experienced increased in-hospital major adverse events (20% vs 12%; P < .0001) including myocardial infarction, congestive heart failure exacerbation

  10. What to Expect during Coronary Artery Bypass Grafting

    MedlinePlus

    ... NHLBI on Twitter. What To Expect During Coronary Artery Bypass Grafting Coronary artery bypass grafting (CABG) requires ... surgery to newer, less-invasive methods. Traditional Coronary Artery Bypass Grafting This type of surgery usually lasts ...

  11. Coronary Artery Bypass Surgery: MedlinePlus Health Topic

    MedlinePlus

    ... arteries from becoming clogged again. NIH: National Heart, Lung, and Blood Institute Start Here Coronary Artery Bypass (Texas Heart ... in Spanish Coronary Artery Bypass Grafting (National Heart, Lung, and Blood Institute) What Is Coronary Bypass Surgery? (American Heart ...

  12. Gut microbiota after Roux-en-Y gastric bypass and sleeve gastrectomy in a diabetic rat model: Increased diversity and associations of discriminant genera with metabolic changes.

    PubMed

    Guo, Yan; Liu, Chao-Qian; Shan, Cheng-Xiang; Chen, Yue; Li, Hui-Hua; Huang, Zhi-Ping; Zou, Da-Jin

    2017-03-01

    Recent work with gut microbiota after bariatric surgery is limited, and the results have not been in agreement. Given the role of the gut microbiota in regulating host metabolism, we explored the effect of Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) on the modifications of gut microbiota with regard to the potential influence of food intake and/or weight loss and examined their links with host metabolism. Zucker diabetic fatty rats were divided into the following groups: RYGB; sham-operated with pair-fed as RYGB; sham-operated fed ad libitum; and SG. The metabolic effects and gut microbiota profile were analyzed 10 weeks postoperatively. Associations between discriminating genera and metabolic markers after RYGB were explored. The 2 procedures induced similar glucose improvement and increased flora diversity after 10 weeks compared with sham-operated groups. RYGB induced a marked higher relative abundance of Proteobacteria/Gammaproteobacteria and Betaproteobacteria and increased emergence of Fusobacteria and Clostridium, whereas SG resulted in more abundant Actinobacteria compared with other groups. Most of the 12 discriminant genera correlated with changes in metabolic phenotype, but only 28.6% of these correlations were independent of weight, and 4 discriminant genera still negatively correlated with serum insulin level independent of food intake and weight loss after RYGB. These data demonstrate that RYGB and SG surgery produced similar diversity but different microbiota compositions changes in Zucker diabetic fatty rats. These findings stimulate deeper explorations of functions of the discriminate microbiota and the mechanisms linking postsurgical modulation of gut microbiota and improvements in insulin resistance.

  13. Design concepts for low-cost composite turbofan engine frame

    NASA Technical Reports Server (NTRS)

    Mitchell, S. C.; Stoffer, L. J.

    1980-01-01

    Design concepts for low cost, lightweight composite engine frames were applied to the design requirements for the frame of a commercial, high bypass engine. Four alternative composite frame design concepts identified which consisted of generic type components and subcomponents that could be adapted to use in different locations in the engine and the different engine sizes. A variety of materials and manufacturing methods were projected with a goal for the lowest number of parts at the lowest possible cost. After a preliminary evaluation of all four frame concepts, two designs were selected for an extended design and evaluation which narrowed the final selection down to one frame that was significantly lower in cost and slighty lighter than the other frame. An implementation plan for this lowest cost frame is projected for future development and includes prospects for reducing its weight with proposed unproven, innovative fabrication techniques.

  14. 40 CFR 403.17 - Bypass.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 28 2010-07-01 2010-07-01 true Bypass. 403.17 Section 403.17 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS GENERAL PRE-TREAT-MENT REGULATIONS FOR EXIST-ING AND NEW SOURCES OF POLLUTION § 403.17 Bypass....

  15. 40 CFR 403.17 - Bypass.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 29 2011-07-01 2009-07-01 true Bypass. 403.17 Section 403.17 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS GENERAL PRE-TREAT-MENT REGULATIONS FOR EXIST-ING AND NEW SOURCES OF POLLUTION § 403.17 Bypass....

  16. 40 CFR 403.17 - Bypass.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., damage to the treatment facilities which causes them to become inoperable, or substantial and permanent... does not cause Pretreatment Standards or Requirements to be violated, but only if it also is for... a description of the bypass and its cause; the duration of the bypass, including exact dates...

  17. 40 CFR 403.17 - Bypass.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) Definitions. (1) Bypass means the intentional diversion of wastestreams from any portion of an Industrial User... applicable Pretreatment Standards or Requirements. An Industrial User may allow any bypass to occur which... paragraphs (c) and (d) of this section. (c) Notice. (1) If an Industrial User knows in advance of the...

  18. Evaluation of a Stirling engine heater bypass with the NASA Lewis nodal-analysis performance code

    SciTech Connect

    Sullivan, T.J.

    1986-05-01

    In support of the US Department of Energy's Stirling Engine Highway Vehicle Systems program, the NASA Lewis Research Center investigated whether bypassing the P-40 Stirling engine heater during regenerative cooling would improve the engine thermal efficiency. The investigation was accomplished by using the Lewis nodal-analysis Stirling engine computer model. Bypassing the P-40 Stirling engine heater at full power resulted in a rise in the indicated thermal efficiency from 40.6 to 41.0 percent. For the idealized (some losses not included) heater bypass that was analyzed, this benefit is not considered significant.

  19. By-Pass Diode Temperature Tests of a Solar Array Coupon under Space Thermal Environment Conditions

    NASA Technical Reports Server (NTRS)

    Wright, Kenneth H.; Schneider, Todd A.; Vaughn, Jason A.; Hoang, Bao; Wong, Frankie; Wu, Gordon

    2016-01-01

    By-Pass diodes are a key design feature of solar arrays and system design must be robust against local heating, especially with implementation of larger solar cells. By-Pass diode testing was performed to aid thermal model development for use in future array designs that utilize larger cell sizes that result in higher string currents. Testing was performed on a 56-cell Advanced Triple Junction solar array coupon provided by SSL. Test conditions were vacuum with cold array backside using discrete by-pass diode current steps of 0.25 A ranging from 0 A to 2.0 A.

  20. CFD modeling and experimental verification of a single-stage coaxial Stirling-type pulse tube cryocooler without either double-inlet or multi-bypass operating at 30-35 K using mixed stainless steel mesh regenerator matrices

    NASA Astrophysics Data System (ADS)

    Dang, Haizheng; Zhao, Yibo

    2016-09-01

    This paper presents the CFD modeling and experimental verifications of a single-stage inertance tube coaxial Stirling-type pulse tube cryocooler operating at 30-35 K using mixed stainless steel mesh regenerator matrices without either double-inlet or multi-bypass. A two-dimensional axis-symmetric CFD model with the thermal non-equilibrium mode is developed to simulate the internal process, and the underlying mechanism of significantly reducing the regenerator losses with mixed matrices is discussed in detail based on the given six cases. The modeling also indicates that the combination of the given different mesh segments can be optimized to achieve the highest cooling efficiency or the largest exergy ratio, and then the verification experiments are conducted in which the satisfactory agreements between simulated and tested results are observed. The experiments achieve a no-load temperature of 27.2 K and the cooling power of 0.78 W at 35 K, or 0.29 W at 30 K, with an input electric power of 220 W and a reject temperature of 300 K.

  1. Particle Trajectory and Icing Analysis of the E(sup 3) Turbofan Engine Using LEWICE3D Version 3

    NASA Technical Reports Server (NTRS)

    Bidwell, Colin S.

    2011-01-01

    Particle trajectory and ice shape calculations were made for the Energy Efficient Engine (E(sup 3)) using the LEWICE3D Version 3 software. The particle trajectory and icing computations were performed using the new "block-to-block" collection efficiency method which has been incorporated into the LEWICE3D Version 3 software. The E(sup 3) was developed by NASA and GE in the early 1980 s as a technology demonstrator and is representative of a modern high bypass turbofan engine. The E(sup 3) flow field was calculated using the NASA Glenn ADPAC turbomachinery flow solver. Computations were performed for the low pressure compressor of the E(sup 3) for a Mach 0.8 cruise condition at 11,887 m assuming a standard warm day for three drop sizes and two drop distributions typically used in aircraft design and certification. Particle trajectory computations were made for water drop sizes of 5, 20, and 100 microns. Particle trajectory and ice shape predictions were made for a 20 micron Langmuir-D distribution and for a 92 mm Super-cooled Large Droplet (SLD) distribution with and without splashing effects for a Liquid Water Content (LWC) of 0.3 g/cu m and an icing time of 30 min. The E3 fan and spinner combination proved to be an effective ice removal mechanism as they removed greater than 36 percent of the mass entering the inlet for the icing cases. The maximum free stream catch fraction for the fan and spinner combination was 0.60 while that on the elements downstream of the fan was 0.03. The non-splashing trajectory and collection efficiency results showed that as drop size increased impingement rates increased on the spinner and fan leaving less mass to impinge on downstream components. The SLD splashing case yielded more mass downstream of the fan than the SLD non-splashing case due to mass being splashed from the upstream inlet lip, spinner and fan components. The ice shapes generated downstream of the fan were either small or nonexistent due to the small available mass

  2. Left ventricular mechanics of counterpulsation and left heart bypass, individually and in combination.

    PubMed

    Rose, E A; Marrin, C A; Bregman, D; Spotnitz, H M

    1979-01-01

    Counterpulsation and left heart bypass devices have been successfully used to salvage patients with severe left ventricular power failure following cardiopulmonary bypass. Each of these techniques is believed to reduce or minimize myocardial work, yet the effects of these devices on the force of myocardial contraction have not been defined. In the present investigation the effects of counterpulsation produced by intravascular (intra-aortic balloon pumping) and extravascular (pulsatile assist device) balloon devices, partial left atrial-aortic bypass, and total bypass on left ventricular mechanics were examined. The devices were studied individually and in combination in 10 anesthetized open-chest dogs. Left ventricular wall stress, external work, and contractility indices were calculated by computer using a changing volume spherical model of the left ventricle. Results indicate that although all currently available circulatory assist devices reduced peak left ventricular wall stress, a spectrum of relative effectiveness progressed from intra-aortic balloon pumping or pulsatile assist device alone through the combination intra-aortic balloon pumping plus the pulsatile assist device. Partial left heart bypass was more effective than intra-aortic balloon pumping plus the pulsatile assist device in reducing peak wall stress, but the difference was small. Total left heart bypass was vastly superior to any of the other modalities tested in its effects on peak wall stress as well as external work. The addition of counterpulsation to partial or total left heart bypass produced minimal changes in left ventricular systolic mechanics.

  3. Electro-impulse de-icing of a turbofan engine inlet

    NASA Technical Reports Server (NTRS)

    Zumwalt, G. W.

    1985-01-01

    The application of electromagnetic impulse deicing (EIDI) systems to turbofan engine inlets on business aircraft has been investigated experimentally. The tests were performed in the Icing Research Tunnel at NASA's Lewis Research Center. The deicing system testbed was a Falcon Fanjet 20 engine nacelle. The effectiveness of various deicing coil configurations and mount designs were compared, and design parameters were developed specifically for EIDI systems in turbofan engines. Flight tests were also carried out at altitudes in the range 3000-6000 ft corresponding to a temperature range of -3 to -8 C. It is shown that the ice particles removed from the engine inlet by the deicing system were small enough for the engine to ingest. Tentative design specifications are given with respect to the optimum coil configuration, and operating power of a EIDI production candidate.

  4. Evaluation of an Outer Loop Retrofit Architecture for Intelligent Turbofan Engine Thrust Control

    NASA Technical Reports Server (NTRS)

    Litt, Jonathan S.; Sowers, T. Shane

    2006-01-01

    The thrust control capability of a retrofit architecture for intelligent turbofan engine control and diagnostics is evaluated. The focus of the study is on the portion of the hierarchical architecture that performs thrust estimation and outer loop thrust control. The inner loop controls fan speed so the outer loop automatically adjusts the engine's fan speed command to maintain thrust at the desired level, based on pilot input, even as the engine deteriorates with use. The thrust estimation accuracy is assessed under nominal and deteriorated conditions at multiple operating points, and the closed loop thrust control performance is studied, all in a complex real-time nonlinear turbofan engine simulation test bed. The estimation capability, thrust response, and robustness to uncertainty in the form of engine degradation are evaluated.

  5. CFD Analysis of Core Bypass Phenomena

    SciTech Connect

    Richard W. Johnson; Hiroyuki Sato; Richard R. Schultz

    2010-03-01

    The U.S. Department of Energy is exploring the potential for the VHTR which will be either of a prismatic or a pebble-bed type. One important design consideration for the reactor core of a prismatic VHTR is coolant bypass flow which occurs in the interstitial regions between fuel blocks. Such gaps are an inherent presence in the reactor core because of tolerances in manufacturing the blocks and the inexact nature of their installation. Furthermore, the geometry of the graphite blocks changes over the lifetime of the reactor because of thermal expansion and irradiation damage. The existence of the gaps induces a flow bias in the fuel blocks and results in unexpected increase of maximum fuel temperature. Traditionally, simplified methods such as flow network calculations employing experimental correlations are used to estimate flow and temperature distributions in the core design. However, the distribution of temperature in the fuel pins and graphite blocks as well as coolant outlet temperatures are strongly coupled with the local heat generation rate within fuel blocks which is not uniformly distributed in the core. Hence, it is crucial to establish mechanistic based methods which can be applied to the reactor core thermal hydraulic design and safety analysis. Computational Fluid Dynamics (CFD) codes, which have a capability of local physics based simulation, are widely used in various industrial fields. This study investigates core bypass flow phenomena with the assistance of commercial CFD codes and establishes a baseline for evaluation methods. A one-twelfth sector of the hexagonal block surface is modeled and extruded down to whole core length of 10.704m. The computational domain is divided vertically with an upper reflector, a fuel section and a lower reflector. Each side of the sector grid can be set as a symmetry boundary

  6. CFD Analysis of Core Bypass Phenomena

    SciTech Connect

    Richard W. Johnson; Hiroyuki Sato; Richard R. Schultz

    2009-11-01

    The U.S. Department of Energy is exploring the potential for the VHTR which will be either of a prismatic or a pebble-bed type. One important design consideration for the reactor core of a prismatic VHTR is coolant bypass flow which occurs in the interstitial regions between fuel blocks. Such gaps are an inherent presence in the reactor core because of tolerances in manufacturing the blocks and the inexact nature of their installation. Furthermore, the geometry of the graphite blocks changes over the lifetime of the reactor because of thermal expansion and irradiation damage. The existence of the gaps induces a flow bias in the fuel blocks and results in unexpected increase of maximum fuel temperature. Traditionally, simplified methods such as flow network calculations employing experimental correlations are used to estimate flow and temperature distributions in the core design. However, the distribution of temperature in the fuel pins and graphite blocks as well as coolant outlet temperatures are strongly coupled with the local heat generation rate within fuel blocks which is not uniformly distributed in the core. Hence, it is crucial to establish mechanistic based methods which can be applied to the reactor core thermal hydraulic design and safety analysis. Computational Fluid Dynamics (CFD) codes, which have a capability of local physics based simulation, are widely used in various industrial fields. This study investigates core bypass flow phenomena with the assistance of commercial CFD codes and establishes a baseline for evaluation methods. A one-twelfth sector of the hexagonal block surface is modeled and extruded down to whole core length of 10.704m. The computational domain is divided vertically with an upper reflector, a fuel section and a lower reflector. Each side of the one-twelfth grid can be set as a symmetry boundary

  7. Dynamic Performance of High Bypass Ratio Turbine Engines With Water Ingestion

    NASA Technical Reports Server (NTRS)

    Murthy, S. N. B.

    1996-01-01

    The research on dynamic performance of high bypass turbofan engines includes studies on inlets, turbomachinery and the total engine system operating with air-water mixture; the water may be in vapor, droplet, or film form, and their combinations. Prediction codes (WISGS, WINCOF, WINCOF-1, WINCLR, and Transient Engine Performance Code) for performance changes, as well as changes in blade-casing clearance, have been established and demonstrated in application to actual, generic engines. In view of the continuous changes in water distribution in turbomachinery, the performance of both components and the total engine system must be determined in a time-dependent mode; hence, the determination of clearance changes also requires a time-dependent approach. In general, the performance and clearances changes cannot be scaled either with respect to operating or ingestion conditions. Removal of water prior to phase change is the most effective means of avoiding ingestion effects. Sufficient background has been established to perform definitive, full scale tests on a set of components and a complete engine to establish engine control and operability with various air-water vapor-water mixtures.

  8. Core noise investigation of the CF6-50 turbofan engine

    NASA Technical Reports Server (NTRS)

    Doyle, V. L.

    1980-01-01

    Acoustic data obtained during the running of the CF6-50 turbofan engine on an outdoor test stand are presented. The test was conducted to acquire simultaneous internal and far-field measurements to determine the influence of internally generated noise on the far-field measurements. The data includes internal and far-field narrowband and one-third octave band pressure spectra.

  9. Method and apparatus for rapid thrust increases in a turbofan engine

    NASA Technical Reports Server (NTRS)

    Cornett, J. E.; Corley, R. C.; Fraley, T. O.; Saunders, A. A., Jr. (Inventor)

    1980-01-01

    Upon a landing approach, the normal compressor stator schedule of a fan speed controlled turbofan engine is temporarily varied to substantially close the stators to thereby increase the fuel flow and compressor speed in order to maintain fan speed and thrust. This running of the compressor at an off-design speed substantially reduces the time required to subsequently advance the engine speed to the takeoff thrust level by advancing the throttle and opening the compressor stators.

  10. Turbofan forced mixer-nozzle internal flowfield. Volume 2: Computational fluid dynamic predictions

    NASA Technical Reports Server (NTRS)

    Werle, M. J.; Vasta, V. N.

    1982-01-01

    A general program was conducted to develop and assess a computational method for predicting the flow properties in a turbofan forced mixed duct. The detail assessment of the resulting computer code is presented. It was found that the code provided excellent predictions of the kinematics of the mixing process throughout the entire length of the mixer nozzle. The thermal mixing process between the hot core and cold fan flows was found to be well represented in the low speed portion of the flowfield.

  11. HYDES: A generalized hybrid computer program for studying turbojet or turbofan engine dynamics

    NASA Technical Reports Server (NTRS)

    Szuch, J. R.

    1974-01-01

    This report describes HYDES, a hybrid computer program capable of simulating one-spool turbojet, two-spool turbojet, or two-spool turbofan engine dynamics. HYDES is also capable of simulating two- or three-stream turbofans with or without mixing of the exhaust streams. The program is intended to reduce the time required for implementing dynamic engine simulations. HYDES was developed for running on the Lewis Research Center's Electronic Associates (EAI) 690 Hybrid Computing System and satisfies the 16384-word core-size and hybrid-interface limits of that machine. The program could be modified for running on other computing systems. The use of HYDES to simulate a single-spool turbojet and a two-spool, two-stream turbofan engine is demonstrated. The form of the required input data is shown and samples of output listings (teletype) and transient plots (x-y plotter) are provided. HYDES is shown to be capable of performing both steady-state design and off-design analyses and transient analyses.

  12. Helical type coronary bypass graft performance: Experimental investigations.

    PubMed

    Bernad, Sandor I; Bosioc, Alin I; Bernad, Elena S; Craina, Marius L

    2015-01-01

    Optimal graft design has been an objective of many researchers to find correlations between hemodynamics and graft failure. Compared to planar grafts, the helical graft configurations improve hemodynamic performance including the promotion of flow mixing and reduction of flow stagnation regions. In order to evaluate the advantages and disadvantages of the suggested helical type bypass graft model in comparison to a conventional bypass graft configuration, three experimental models were designed and evaluated. The character of complex vortex structures created in the area between the heel and the occluded section depends on the flow parameters (in the case of the straight graft). We have identified two vortices in the symmetrical plane (proximal and distal to the anastomosis). In the new design of the two-turn helical graft, the stagnation point is eliminated from the anastomoses at different time intervals compared to the conventional straight bypass model The present study indicated that the magnitude of the pressure drop along a helical graft was considerably increased compared to a traditional graft which, while still physiologically advantageous, can be surpassed by an optimal geometry model.

  13. Modeling of gas turbine - solid oxide fuel cell systems for combined propulsion and power on aircraft

    NASA Astrophysics Data System (ADS)

    Waters, Daniel Francis

    This dissertation investigates the use of gas turbine (GT) engine integrated solid oxide fuel cells (SOFCs) to reduce fuel burn in aircraft with large electrical loads like sensor-laden unmanned air vehicles (UAVs). The concept offers a number of advantages: the GT absorbs many SOFC balance of plant functions (supplying fuel, air, and heat to the fuel cell) thereby reducing the number of components in the system; the GT supplies fuel and pressurized air that significantly increases SOFC performance; heat and unreacted fuel from the SOFC are recaptured by the GT cycle offsetting system-level losses; good transient response of the GT cycle compensates for poor transient response of the SOFC. The net result is a system that can supply more electrical power more efficiently than comparable engine-generator systems with only modest (<10%) decrease in power density. Thermodynamic models of SOFCs, catalytic partial oxidation (CPOx) reactors, and three GT engine types (turbojet, combined exhaust turbofan, separate exhaust turbofan) are developed that account for equilibrium gas phase and electrochemical reaction, pressure losses, and heat losses in ways that capture `down-the-channel' effects (a level of fidelity necessary for making meaningful performance, mass, and volume estimates). Models are created in a NASA-developed environment called Numerical Propulsion System Simulation (NPSS). A sensitivity analysis identifies important design parameters and translates uncertainties in model parameters into uncertainties in overall performance. GT-SOFC integrations reduce fuel burn 3-4% in 50 kW systems on 35 kN rated engines (all types) with overall uncertainty <1%. Reductions of 15-20% are possible at the 200 kW power level. GT-SOFCs are also able to provide more electric power (factors >3 in some cases) than generator-based systems before encountering turbine inlet temperature limits. Aerodynamic drag effects of engine-airframe integration are by far the most important

  14. 75 FR 64681 - Airworthiness Directives; General Electric Company (GE) CF6-45 Series and CF6-50 Series Turbofan...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-20

    ..., Massachusetts, on October 8, 2010. Peter A. White, Assistant Manager, Engine and Propeller Directorate, Aircraft... Company (GE) CF6-45 Series and CF6-50 Series Turbofan Engines AGENCY: Federal Aviation Administration (FAA... airworthiness directive (AD) for GE CF6-45 and CF6-50 series turbofan engines. This proposed AD would...

  15. 21 CFR 870.4380 - Cardiopulmonary bypass pump speed control.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Cardiopulmonary bypass pump speed control. 870... Cardiopulmonary bypass pump speed control. (a) Identification. A cardiopulmonary bypass pump speed control is a... control the speed of blood pumps used in cardiopulmonary bypass surgery. (b) Classification. Class...

  16. 21 CFR 870.4380 - Cardiopulmonary bypass pump speed control.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Cardiopulmonary bypass pump speed control. 870... Cardiopulmonary bypass pump speed control. (a) Identification. A cardiopulmonary bypass pump speed control is a... control the speed of blood pumps used in cardiopulmonary bypass surgery. (b) Classification. Class...

  17. 21 CFR 870.4380 - Cardiopulmonary bypass pump speed control.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Cardiopulmonary bypass pump speed control. 870... Cardiopulmonary bypass pump speed control. (a) Identification. A cardiopulmonary bypass pump speed control is a... control the speed of blood pumps used in cardiopulmonary bypass surgery. (b) Classification. Class...

  18. 21 CFR 870.4380 - Cardiopulmonary bypass pump speed control.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Cardiopulmonary bypass pump speed control. 870... Cardiopulmonary bypass pump speed control. (a) Identification. A cardiopulmonary bypass pump speed control is a... control the speed of blood pumps used in cardiopulmonary bypass surgery. (b) Classification. Class...

  19. 21 CFR 870.4310 - Cardiopulmonary bypass coronary pressure gauge.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Cardiopulmonary bypass coronary pressure gauge... Cardiopulmonary bypass coronary pressure gauge. (a) Identification. A cardiopulmonary bypass coronary pressure gauge is a device used in cardiopulmonary bypass surgery to measure the pressure of the blood...

  20. 30 CFR 56.19018 - Overtravel by-pass switches.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Overtravel by-pass switches. 56.19018 Section... Hoisting Hoists § 56.19018 Overtravel by-pass switches. When an overtravel by-pass switch is installed, the... switch is held in the closed position by the hoistman. The overtravel by-pass switch shall...

  1. 30 CFR 57.19018 - Overtravel by-pass switches.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Overtravel by-pass switches. 57.19018 Section... Hoisting Hoists § 57.19018 Overtravel by-pass switches. When an overtravel by-pass switch is installed, the... switch is held in the closed position by the hoistman. The overtravel by-pass switch shall...

  2. 21 CFR 870.4380 - Cardiopulmonary bypass pump speed control.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cardiopulmonary bypass pump speed control. 870... Cardiopulmonary bypass pump speed control. (a) Identification. A cardiopulmonary bypass pump speed control is a... control the speed of blood pumps used in cardiopulmonary bypass surgery. (b) Classification. Class...

  3. The Benefits of Photorespiratory Bypasses: How Can They Work?1[OPEN

    PubMed Central

    Xin, Chang-Peng; Tholen, Danny; Devloo, Vincent; Zhu, Xin-Guang

    2015-01-01

    Bypassing the photorespiratory pathway is regarded as a way to increase carbon assimilation and, correspondingly, biomass production in C3 crops. Here, the benefits of three published photorespiratory bypass strategies are systemically explored using a systems-modeling approach. Our analysis shows that full decarboxylation of glycolate during photorespiration would decrease photosynthesis, because a large amount of the released CO2 escapes back to the atmosphere. Furthermore, we show that photosynthesis can be enhanced by lowering the energy demands of photorespiration and by relocating photorespiratory CO2 release into the chloroplasts. The conductance of the chloroplast membranes to CO2 is a key feature determining the benefit of the relocation of photorespiratory CO2 release. Although our results indicate that the benefit of photorespiratory bypasses can be improved by increasing sedoheptulose bisphosphatase activity and/or increasing the flux through the bypass, the effectiveness of such approaches depends on the complex regulation between photorespiration and other metabolic pathways. PMID:25516604

  4. Frataxin-bypassing Isu1: characterization of the bypass activity in cells and mitochondria.

    PubMed

    Yoon, Heeyong; Knight, Simon A B; Pandey, Alok; Pain, Jayashree; Zhang, Yan; Pain, Debkumar; Dancis, Andrew

    2014-04-01

    Frataxin is a conserved mitochondrial protein, and deficiency underlies the neurodegenerative disease Friedreich's ataxia. Frataxin interacts with the core machinery for Fe-S cluster assembly in mitochondria. Recently we reported that in frataxin-deleted yeast strains, a spontaneously occurring mutation in one of two genes encoding redundant Isu scaffold proteins, bypassed the mutant phenotypes. In the present study we created strains expressing a single scaffold protein, either Isu1 or the bypass mutant M107I Isu1. Our results show that in the frataxin-deletion strain expressing the bypass mutant Isu1, cell growth, Fe-S cluster protein activities, haem proteins and iron homoeostasis were restored to normal or close to normal. The bypass effects were not mediated by changes in Isu1 expression level. The persulfide-forming activity of the cysteine desulfurase was diminished in the frataxin deletion (∆yfh1 ISU1) and was improved by expression of the bypass Isu1 (∆yfh1 M107I ISU1). The addition of purified bypass M107I Isu1 protein to a ∆yfh1 lysate conferred similar enhancement of cysteine desulfurase as did frataxin, suggesting that this effect contributed to the bypass mechanism. Fe-S cluster-forming activity in isolated mitochondria was stimulated by the bypass Isu1, albeit at a lower rate. The rescuing effects of the bypass Isu1 point to ways that the core defects in Friedreich's ataxia mitochondria can be restored.

  5. Heart bypass surgery - minimally invasive - discharge

    MedlinePlus

    ... thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest . 2012;141(2 ... bypass surgery - minimally invasive Heart failure - overview High blood cholesterol ...

  6. Pharmacological Bypass of Cockayne Syndrome B Function in Neuronal Differentiation

    PubMed Central

    Wang, Yuming; Jones-Tabah, Jace; Chakravarty, Probir; Stewart, Aengus; Muotri, Alysson; Laposa, Rebecca R.; Svejstrup, Jesper Q.

    2016-01-01

    Summary Cockayne syndrome (CS) is a severe neurodevelopmental disorder characterized by growth abnormalities, premature aging, and photosensitivity. Mutation of Cockayne syndrome B (CSB) affects neuronal gene expression and differentiation, so we attempted to bypass its function by expressing downstream target genes. Intriguingly, ectopic expression of Synaptotagmin 9 (SYT9), a key component of the machinery controlling neurotrophin release, bypasses the need for CSB in neuritogenesis. Importantly, brain-derived neurotrophic factor (BDNF), a neurotrophin implicated in neuronal differentiation and synaptic modulation, and pharmacological mimics such as 7,8-dihydroxyflavone and amitriptyline can compensate for CSB deficiency in cell models of neuronal differentiation as well. SYT9 and BDNF are downregulated in CS patient brain tissue, further indicating that sub-optimal neurotrophin signaling underlies neurological defects in CS. In addition to shedding light on cellular mechanisms underlying CS and pointing to future avenues for pharmacological intervention, these data suggest an important role for SYT9 in neuronal differentiation. PMID:26972010

  7. Exhaust gas bypass valve control for thermoelectric generator

    SciTech Connect

    Reynolds, Michael G; Yang, Jihui; Meisner, Greogry P.; Stabler, Francis R.; De Bock, Hendrik Pieter Jacobus; Anderson, Todd Alan

    2012-09-04

    A method of controlling engine exhaust flow through at least one of an exhaust bypass and a thermoelectric device via a bypass valve is provided. The method includes: determining a mass flow of exhaust exiting an engine; determining a desired exhaust pressure based on the mass flow of exhaust; comparing the desired exhaust pressure to a determined exhaust pressure; and determining a bypass valve control value based on the comparing, wherein the bypass valve control value is used to control the bypass valve.

  8. Experimental and Analytic Study on the Core Bypass Flow in a Very High Temperature Reactor

    SciTech Connect

    Richard Schultz

    2012-04-01

    Core bypass flow has been one of key issues in the very high temperature reactor (VHTR) design for securing core thermal margins and achieving target temperatures at the core exit. The bypass flow in a prismatic VHTR core occurs through the control element holes and the radial and axial gaps between the graphite blocks for manufacturing and refueling tolerances. These gaps vary with the core life cycles because of the irradiation swelling/shrinkage characteristic of the graphite blocks such as fuel and reflector blocks, which are main components of a core's structure. Thus, the core bypass flow occurs in a complicated multidimensional way. The accurate prediction of this bypass flow and counter-measures to minimize it are thus of major importance in assuring core thermal margins and securing higher core efficiency. Even with this importance, there has not been much effort in quantifying and accurately modeling the effect of the core bypass flow. The main objectives of this project were to generate experimental data for validating the software to be used to calculate the bypass flow in a prismatic VHTR core, validate thermofluid analysis tools and their model improvements, and identify and assess measures for reducing the bypass flow. To achieve these objectives, tasks were defined to (1) design and construct experiments to generate validation data for software analysis tools, (2) determine the experimental conditions and define the measurement requirements and techniques, (3) generate and analyze the experimental data, (4) validate and improve the thermofluid analysis tools, and (5) identify measures to control the bypass flow and assess its performance in the experiment.

  9. MHD Energy Bypass Scramjet Engine

    NASA Technical Reports Server (NTRS)

    Mehta, Unmeel B.; Bogdanoff, David W.; Park, Chul; Arnold, Jim (Technical Monitor)

    2001-01-01

    Revolutionary rather than evolutionary changes in propulsion systems are most likely to decrease cost of space transportation and to provide a global range capability. Hypersonic air-breathing propulsion is a revolutionary propulsion system. The performance of scramjet engines can be improved by the AJAX energy management concept. A magneto-hydro-dynamics (MHD) generator controls the flow and extracts flow energy in the engine inlet and a MHD accelerator downstream of the combustor accelerates the nozzle flow. A progress report toward developing the MHD technology is presented herein. Recent theoretical efforts are reviewed and ongoing experimental efforts are discussed. The latter efforts also include an ongoing collaboration between NASA, the US Air Force Research Laboratory, US industry, and Russian scientific organizations. Two of the critical technologies, the ionization of the air and the MHD accelerator, are briefly discussed. Examples of limiting the combustor entrance Mach number to a low supersonic value with a MHD energy bypass scheme are presented, demonstrating an improvement in scramjet performance. The results for a simplified design of an aerospace plane show that the specific impulse of the MHD-bypass system is better than the non-MHD system and typical rocket over a narrow region of flight speeds and design parameters. Equilibrium ionization and non-equilibrium ionization are discussed. The thermodynamic condition of air at the entrance of the engine inlet determines the method of ionization. The required external power for non-equilibrium ionization is computed. There have been many experiments in which electrical power generation has successfully been achieved by magneto-hydrodynamic (MHD) means. However, relatively few experiments have been made to date for the reverse case of achieving gas acceleration by the MHD means. An experiment in a shock tunnel is described in which MHD acceleration is investigated experimentally. MHD has several

  10. Flow Simulation of Supersonic Inlet with Bypass Annular Duct

    NASA Technical Reports Server (NTRS)

    Kim, HyoungJin; Kumano, Takayasu; Liou, Meng-Sing; Povinelli, Louis A.; Conners, Timothy R.

    2011-01-01

    A relaxed isentropic compression supersonic inlet is a new concept that produces smaller cowl drag than a conventional inlet, but incurs lower total pressure recovery and increased flow distortion in the (radially) outer flowpath. A supersonic inlet comprising a bypass annulus to the relaxed isentropic compression inlet dumps out airflow of low quality through the bypass duct. A reliable computational fluid dynamics solution can provide considerable useful information to ascertain quantitatively relative merits of the concept, and further provide a basis for optimizing the design. For a fast and reliable performance evaluation of the inlet performance, an equivalent axisymmetric model whose area changes accounts for geometric and physical (blockage) effects resulting from the original complex three-dimensional configuration is proposed. In addition, full three-dimensional calculations are conducted for studying flow phenomena and verifying the validity of the equivalent model. The inlet-engine coupling is carried out by embedding numerical propulsion system simulation engine data into the flow solver for interactive boundary conditions at the engine fan face and exhaust plane. It was found that the blockage resulting from complex three-dimensional geometries in the bypass duct causes significant degradation of inlet performance by pushing the terminal normal shock upstream.

  11. Bypass diode for a solar cell

    DOEpatents

    Rim, Seung Bum [Palo Alto, CA; Kim, Taeseok [San Jose, CA; Smith, David D [Campbell, CA; Cousins, Peter J [Menlo Park, CA

    2012-03-13

    Bypass diodes for solar cells are described. In one embodiment, a bypass diode for a solar cell includes a substrate of the solar cell. A first conductive region is disposed above the substrate, the first conductive region of a first conductivity type. A second conductive region is disposed on the first conductive region, the second conductive region of a second conductivity type opposite the first conductivity type.

  12. Monsanto may bypass NIH in microbe test.

    PubMed

    Sun, Marjorie

    1985-01-11

    The Monsanto Company is planning to ask the Environmental Protection Agency for clearance to field test a genetically engineered microbial pesticide, bypassing the traditional approval process of the National Institutes of Health. Although only federally funded institutions are required to obtain NIH approval for genetic engineering tests, Monsanto is the first company to bypass the NIH regulatory process, which has become mired in a lawsuit brought by Jeremy Rifkin.

  13. Prophylactic digitalization for coronary artery bypass surgery.

    PubMed

    Johnson, L W; Dickstein, R A; Fruehan, C T; Kane, P; Potts, J L; Smulyan, H; Webb, W R; Eich, R H

    1976-05-01

    One hundred and twenty patients undergoing aortocoronary bypass procedures were randomly placed into control and digitalized groups. All were initially in normal sinus rhythm and without evidence of congestive heart failure. Supraventricular arrhythmias occurred in 17 of 66 controls and in only three of 54 digitalized patients (P less than 0.01). There was no evidence of digitals toxicity. Based on this evidence we recommend prophylactic digitalization for patients having aortocoronary bypass operations.

  14. The Dalles Dam juvenile bypass electrical systems

    SciTech Connect

    Bannister, B.D.; Luck, B.

    1995-12-31

    The Corps of Engineers is in the process of providing a juvenile fish bypass system at The Dalles Lock and Dam project on the lower Columbia River. This system is intended to preserve and enhance the dwindling stocks of wild anadromous fish. The impact of the proposed facilities on the electrical systems and on plant operations are developed along with descriptions of the special bypass features including the incorporation of provisions for a future small hydropower generator.

  15. Rotordynamic analysis of asymmetric turbofan rotor due to fan blade-loss event with contact-impact rub loads

    NASA Astrophysics Data System (ADS)

    Sinha, Sunil K.

    2013-04-01

    Loss of a blade from a running turbofan rotor introduces not only huge imbalance into the dynamical system rather it makes the entire rotor asymmetric as well. In a nonsymmetric rotor, the various terms of mass, gyroscopic and stiffness matrices also become time-dependent. In this paper, all the dynamical equations include the effect of the rotary inertia and gyroscopic moments as a result of both shaft bending as well as staggered blades flexing in-and-out of the plane of the disk. The governing equations also account for internal material damping in the shaft and the external damping in the support bearing system. In addition to the unbalance load at the disk location, the shaft may also be subjected to a torque and axial forces. Here, the fan blades are modeled as pre-twisted thin shallow shells. They have coupled flexural-torsional motion in the lateral out-of-plane direction as well as extensional degrees-of-freedom in the longitudinal spanwise direction of the blade airfoil. The effect of blade tip rub forces being transmitted to the shaft are analyzed in terms of the dynamic stability of the rotor, especially during windmilling.

  16. Identification and measurement of combustion noise from a turbofan engine using correlation and coherence techniques. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Karchmer, A. M.

    1977-01-01

    Fluctuating pressure measurements within the combustor and tailpipe of a turbofan engine are made simultaneously with far field acoustic measurements. The pressure measurements within the engine are accomplished with cooled semi-infinite waveguide probes utilizing conventional condenser microphones as the transducers. The measurements are taken over a broad range of engine operating conditions and for 16 far field microphone positions between 10 deg and 160 deg relative to the engine inlet axis. Correlation and coherence techniques are used to determine the relative phase and amplitude relationships between the internal pressures and far field acoustic pressures. The results indicate that the combustor is a low frequency source region for acoustic propagation through the tailpipe and out to the far field. Specifically, it is found that the relation between source pressure and the resulting sound pressure involves a 180 deg phase shift. The latter result is obtained by Fourier transforming the cross correlation function between the source pressure and acoustic pressure after removing the propagation delay time. Further, it is found that the transfer function between the source pressure and acoustic pressure has a magnitude approximately proportional to frequency squared. These results are shown to be consistent with a model using a modified source term in Lighthill's turbulence stress tensor, wherein the fluctuating Reynolds stresses are replaced with the pressure fluctuations due to fluctuating entropy.

  17. Analytical study of the effects of wind tunnel turbulence on turbofan rotor noise. [NASA Ames 40 by 80 foot wind tunnel

    NASA Technical Reports Server (NTRS)

    Gliebe, P. R.; Kerschen, E. J.

    1979-01-01

    The influence of tunnel turbulence on turbofan rotor noise was carried out to evaluate the effectiveness of the NASA Ames 40 by 80 foot tunnel in simulating flight levels of fan noise. A previously developed theory for predicting rotor/turbulence interaction noise was refined and extended to include first-order effects of inlet turbulence anisotropy. This theory was then verified by carrying out extensive data/theory comparisons. The resulting model computer program was then employed to carry out a parametric study of the effects of fan size, blade number, and operating line on rotor/turbulence noise for outdoor test stand. NASA Ames wind tunnel, and flight inlet turbulence conditions. A major result of this study is that although wind tunnel rotor/turbulence noise levels are not as low as flight levels they are substantially lower than the outdoor test stand levels and do not mask other sources of fan noise.

  18. Age and morphodynamics of a sandy beach fronted by a macrotidal mud flat along the west coast of Korea: a lateral headland bypass model for beach-dune formation

    NASA Astrophysics Data System (ADS)

    Chang, Tae Soo; Hong, Seok Hwi; Chun, Seung Soo; Choi, Jeong-Heon

    2016-11-01

    -dune deposits are underlain by muddy tidal flat deposits, which results in a clear upward coarsening grain-size trend and thus intimates transgressive deposition associated with sea-level rise over the past 7-8 ka. However, a time gap of 4-5 thousand years between the tidal flat and the beach-dune deposits indicates that there is no genetic link between the two depositional systems. As the modern beach-dune system is remote from the former landward limit of the tidal flat, a continuous retreat model must be rejected. Instead, a lateral headland bypassing model, in which sand supplied alongshore progressively encroached the tidal flat, is more plausible. In the light of this interpretation, many of the barrier beach-lagoon models proposed for the macrotidal west coast of Korea need to be reconsidered.

  19. Brain microvascular function during cardiopulmonary bypass

    SciTech Connect

    Sorensen, H.R.; Husum, B.; Waaben, J.; Andersen, K.; Andersen, L.I.; Gefke, K.; Kaarsen, A.L.; Gjedde, A.

    1987-11-01

    Emboli in the brain microvasculature may inhibit brain activity during cardiopulmonary bypass. Such hypothetical blockade, if confirmed, may be responsible for the reduction of cerebral metabolic rate for glucose observed in animals subjected to cardiopulmonary bypass. In previous studies of cerebral blood flow during bypass, brain microcirculation was not evaluated. In the present study in animals (pigs), reduction of the number of perfused capillaries was estimated by measurements of the capillary diffusion capacity for hydrophilic tracers of low permeability. Capillary diffusion capacity, cerebral blood flow, and cerebral metabolic rate for glucose were measured simultaneously by the integral method, different tracers being used with different circulation times. In eight animals subjected to normothermic cardiopulmonary bypass, and seven subjected to hypothermic bypass, cerebral blood flow, cerebral metabolic rate for glucose, and capillary diffusion capacity decreased significantly: cerebral blood flow from 63 to 43 ml/100 gm/min in normothermia and to 34 ml/100 gm/min in hypothermia and cerebral metabolic rate for glucose from 43.0 to 23.0 mumol/100 gm/min in normothermia and to 14.1 mumol/100 gm/min in hypothermia. The capillary diffusion capacity declined markedly from 0.15 to 0.03 ml/100 gm/min in normothermia but only to 0.08 ml/100 gm/min in hypothermia. We conclude that the decrease of cerebral metabolic rate for glucose during normothermic cardiopulmonary bypass is caused by interruption of blood flow through a part of the capillary bed, possibly by microemboli, and that cerebral blood flow is an inadequate indicator of capillary blood flow. Further studies must clarify why normal microvascular function appears to be preserved during hypothermic cardiopulmonary bypass.

  20. The effects of perceived social support on quality of life in patients awaiting coronary artery bypass grafting and their partners: testing dyadic dynamics using the Actor-Partner Interdependence Model.

    PubMed

    Thomson, Patricia; Molloy, Gerard J; Chung, Misook L

    2012-01-01

    Patients awaiting coronary artery bypass grafting (CABG) need support from their partners or family caregivers to manage their self care successfully and to maximise quality of life. Partners need social support to help overcome the stressful tasks of an unexpected caregiving role. It is not known whether the individual's perceived social support contributes to their own, as well as their partner's quality of life. The aims of this study were to assess differences in social support and quality of life in patients and partners awaiting CABG, and to examine whether patients' and partners' perceived social support predicted their own, as well as their partner's quality of life before CABG. This cross-sectional study recruited 84 dyads (patients 84% males, aged 64.5 years and partners 94% females, aged 61.05 years). Perceived social support was assessed using the Medical Outcomes Study Social Support survey, with sub-scales for informational/emotional support, affectionate support, tangible support and positive social interaction. Quality of life was assessed using the Short-Form 12 Health Survey. Dyadic data were analysed using the Actor-Partner Interdependence Model, with distinguishable dyad regression. Results revealed the patients' informational/emotional support exhibited an actor effect on their own mental health (ß = 0.19, p = 0.001); indicating those with low informational/emotional support had poorer mental health. There was a partner effect of the patients' informational/emotional support on their partner's mental health (ß = 0.14, p = 0.024), indicating the patients' informational/emotional support was associated with the partner's mental health. None of the other types of social support exhibited an actor effect or a partner effect on the patient's or the partner's mental or physical health. More research into the relationship between social support and mental health is needed to help inform the design of interventions that target the dyad.

  1. Study of quiet turbofan STOL aircraft for short-haul transportation. Volume 1: Summary

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Conceptual designs of Quiet Turbofan STOL Short-Haul Transport Aircraft for the mid-1980 time period are developed and analyzed to determine their technical, operational, and economic feasibility. A matrix of aircraft using various high-lift systems and design parameters are considered. Variations in aircraft characteristics, airport geometry and location, and operational techniques are analyzed systematically to determine their effects on the market, operating economics, and community acceptance. The total systems approach is considered to be critically important in analyzing the potential of STOL aircraft to reduce noise pollution and alleviate the increasing air corridor and airport congestion.

  2. Computation of three-dimensional flow in turbofan mixers and comparison with experimental data

    NASA Technical Reports Server (NTRS)

    Povinelli, L. A.; Anderson, B. H.; Gerstenmaier, W.

    1980-01-01

    A three dimensional, viscous computer code was used to calculate the mixing downstream of a typical turbofan mixer geometry. Experimental data obtained using pressure and temperature rakes at the lobe and nozzle exit stations were used to validate the computer results. The relative importance of turbulence in the mixing phenomenon as compared with the streamwise vorticity set up by the secondary flows was determined. The observations suggest that the generation of streamwise vorticity plays a significant role in determining the temperature distribution at the nozzle exit plane.

  3. Statistical Turbofan Architecture Management for Use in a Supercirculation Wing Aircraft

    NASA Astrophysics Data System (ADS)

    Drãgan, Valeriu

    2012-12-01

    The paper presents an attempt to determine weather the architecture difference between the two spool and three spool turbofan engines can have any significant effect uppon their use in super circulation wing (SCW) aircraft. Such aircraft have been experimented with since 1970's and have been revived because of growing interest in silent STOL aircraft. The approach used is statistical, i.e. actual data provided by engine manufacturers and regulating authorities such as ICAO and EASA was used to derive certain relevant parameters which were then analyzed and conclusions were formulated.

  4. Development of dynamic simulation of TF34-GE-100 turbofan engine with post-stall capability

    NASA Technical Reports Server (NTRS)

    Krosel, S. M.

    1984-01-01

    This paper describes the development of a hybrid computer simulation of a TF34-GE-100 turbofan engine with post-stall capability. The simulation operates in real-time and will be used to test and evaluate stall recovery control modes for this engine. The simulation calculations are performed by an analog computer with a peripheral multivariable function generation unit used for computing bivariate functions. Tabular listings of simulation variables are obtained by interfacing to a digital computer and using a custom software package for data collection and display.

  5. Development of dynamic simulation of TF34-GE-100 turbofan engine with post-stall capability

    NASA Technical Reports Server (NTRS)

    Krosel, S. M.

    1984-01-01

    This paper describes the development of a hybrid computer simulation of a TF34-GE-100 turbofan engine with post-stall capability. The simulation operates in real-time and will be used to test and evaluate stall recovery control modes for this engine. The simulation calculations are performed by an analog computer with a peripheral multivariable function generation unit used for computing bivariate functions. Tabular listings of a simulation variables are obtained by interfacing to a digital computer and using a custom software package for data collection and display.

  6. Preliminary experiments on active control of fan noise from a turbofan engine

    NASA Technical Reports Server (NTRS)

    Thomas, R. H.; Burdisso, R. A.; Fuller, C. R.; O'Brien, W. F.

    1993-01-01

    In the preliminary experiments reported here, active acoustic sources positioned around the circumference of a turbofan engine were used to control the fan noise radiated forward through the inlet. The main objective was to demonstrate the potential of active techniques to alleviate the noise pollution that will be produced by the next generation of larger engines. A reduction of up to 19 dB in the radiation directivity was demonstrated in a zone that encompasses a 30-deg angle, near the error sensor, while spillover effects were observed toward the lateral direction. The simultaneous control of two tones was also demonstrated using two identical controllers in a parallel control configuration.

  7. Measurement of gaseous emissions from a turbofan engine at simulated altitude conditions

    NASA Technical Reports Server (NTRS)

    Diehl, L. A.; Biaglow, J. A.

    1974-01-01

    Gaseous emission from a TFE 731-2 turbofan engine were measured over a range of fuel-air ratios from idle to full power at simulated from near sea level to 13,200 m. Carbon monoxide and unburned hydrocarbon emissions were highest at idle and lowest at high power settings; oxides of nitrogen exhibited the reverse trend. Carbon monoxide and unburned hydrocarbon levels decreased with increasing altitude. Oxides of nitrogen emissions were successfully correlated by a parametric group of combustor operating variables.

  8. Effects of fan inlet temperature disturbances on the stability of a turbofan engine

    NASA Technical Reports Server (NTRS)

    Abdelwahab, M.

    1981-01-01

    The effects of steady-state and time-dependent fan inlet total temperature disturbances on the stability of a TF30-P-3 turbofan engine were determined. Disturbances were induced by a gaseous-hydrogen-fueled burner system installed upstream of the fan inlet. Data were obtained at a fan inlet Reynolds number index of 0.50 and at a low-pressure-rotor corrected speed of 90 percent of military speed. All tests were conducted with a 90 deg extent of the fan inlet circumference exposed to above-average temperatures.

  9. Study of quiet turbofan STOL aircraft for short-haul transportation. Volume 6: Systems analysis

    NASA Technical Reports Server (NTRS)

    1973-01-01

    A systems analysis of the quiet turbofan aircraft for short-haul transportation was conducted. The purpose of the study was to integrate the representative data generated by aircraft, market, and economic analyses. Activities of the study were to develop the approach and to refine the methodologies for analytic tradeoff, and sensitivity studies of propulsive lift conceptual aircraft and their performance in simulated regional airlines. The operations of appropriate airlines in each of six geographic regions of the United States were simulated. The offshore domestic regions were evaluated to provide a complete domestic evaluation of the STOL concept applicability.

  10. Study of small civil turbofan engines applicable to military trainer airplanes

    NASA Technical Reports Server (NTRS)

    Heldenbrand, R. W.; Merrill, G. L.; Burnett, G. A.

    1975-01-01

    Small turbofan engine design concepts were applied to military trainer airplanes to establish the potential for commonality between civil and military engines. Several trainer configurations were defined and studied. A ""best'' engine was defined for the trainer mission, and sensitivity analyses were performed to determine the effects on airplane size and efficiency of wing loading, power loading, configuration, aerodynamic quality, and engine quality. It is concluded that a small civil aircraft is applicable to military trainer airplanes. Aircraft designed with these engines are smaller, less costly, and more efficient than existing trainer aircraft.

  11. Effect of spatial inlet temperature and pressure distortion on turbofan engine stability

    NASA Technical Reports Server (NTRS)

    Mehalic, Charles M.

    1988-01-01

    The effects of circumferential and radial inlet temperature distortion, circumferential pressure distortion, and combined temperature and pressure distortion on the stability of an advanced turbofan engine were investigated experimentally at simulated altitude conditions. With circumferential and radial inlet temperature distortion, a flow instability generated by the fan operating near stall caused the high-pressure compressor to surge at, or near, the same time as the fan. The effect of combined distortion was dependent on the relative location of the high-temperature and low-pressure regions; high-pressure compressor stalls occurred when the regions coincided, and fan stalls occurred with the regions separated.

  12. Study of quiet turbofan STOL aircraft for short-haul transportation. Volume 2: Aircraft

    NASA Technical Reports Server (NTRS)

    1973-01-01

    A study of the quiet turbofan STOL aircraft for short haul transportation was conducted. The objectives of the study were as follows: (1) to determine the relationships between STOL characteristics and economic and social viability of short haul air transportation, (2) to identify critical technology problems involving introduction of STOL short haul systems, (3) to define representative aircraft configurations, characteristics, and costs, and (4) to identify high payoff technology areas to improve STOL systems. The analyses of the aircraft designs which were generated to fulfill the objectives are summarized. The baseline aircraft characteristics are documented and significant trade studies are presented.

  13. GENENG: A program for calculating design and off-design performance for turbojet and turbofan engines

    NASA Technical Reports Server (NTRS)

    Koenig, R. W.; Fishbach, L. H.

    1972-01-01

    A computer program entitled GENENG employs component performance maps to perform analytical, steady state, engine cycle calculations. Through a scaling procedure, each of the component maps can be used to represent a family of maps (different design values of pressure ratios, efficiency, weight flow, etc.) Either convergent or convergent-divergent nozzles may be used. Included is a complete FORTRAN 4 listing of the program. Sample results and input explanations are shown for one-spool and two-spool turbojets and two-spool separate- and mixed-flow turbofans operating at design and off-design conditions.

  14. Status report - DARPA/NASA convertible turbofan/turboshaft engine program

    NASA Technical Reports Server (NTRS)

    Bellin, A. I.; Brooks, A.

    1983-01-01

    A development status report is presented for the NASA/Defense Advanced Research Projects Agency convertible turbofan-turboshaft engine, which can power a high speed rotorcraft in vertical flight, as well as in horizontal flight up to speeds of Mach 0.85. The basis for this development program is a modified TF34-GE-400 engine. Program objectives include both the demonstration of dual output mode (jet thrust and shaft horsepower) capability and the development of a control system which will operate the engine in either mode and convert operation between the modes.

  15. Net thrust calculation sensitivity of an afterburning turbofan engine to variations in input parameters

    NASA Technical Reports Server (NTRS)

    Hughes, D. L.; Ray, R. J.; Walton, J. T.

    1985-01-01

    The calculated value of net thrust of an aircraft powered by a General Electric F404-GE-400 afterburning turbofan engine was evaluated for its sensitivity to various input parameters. The effects of a 1.0-percent change in each input parameter on the calculated value of net thrust with two calculation methods are compared. This paper presents the results of these comparisons and also gives the estimated accuracy of the overall net thrust calculation as determined from the influence coefficients and estimated parameter measurement accuracies.

  16. The Use of Probabilistic Methods to Evaluate the Systems Impact of Component Design Improvements on Large Turbofan Engines

    NASA Technical Reports Server (NTRS)

    Packard, Michael H.

    2002-01-01

    Probabilistic Structural Analysis (PSA) is now commonly used for predicting the distribution of time/cycles to failure of turbine blades and other engine components. These distributions are typically based on fatigue/fracture and creep failure modes of these components. Additionally, reliability analysis is used for taking test data related to particular failure modes and calculating failure rate distributions of electronic and electromechanical components. How can these individual failure time distributions of structural, electronic and electromechanical component failure modes be effectively combined into a top level model for overall system evaluation of component upgrades, changes in maintenance intervals, or line replaceable unit (LRU) redesign? This paper shows an example of how various probabilistic failure predictions for turbine engine components can be evaluated and combined to show their effect on overall engine performance. A generic model of a turbofan engine was modeled using various Probabilistic Risk Assessment (PRA) tools (Quantitative Risk Assessment Software (QRAS) etc.). Hypothetical PSA results for a number of structural components along with mitigation factors that would restrict the failure mode from propagating to a Loss of Mission (LOM) failure were used in the models. The output of this program includes an overall failure distribution for LOM of the system. The rank and contribution to the overall Mission Success (MS) is also given for each failure mode and each subsystem. This application methodology demonstrates the effectiveness of PRA for assessing the performance of large turbine engines. Additionally, the effects of system changes and upgrades, the application of different maintenance intervals, inclusion of new sensor detection of faults and other upgrades were evaluated in determining overall turbine engine reliability.

  17. Experimental Investigation of By-pass Transition

    NASA Astrophysics Data System (ADS)

    Sengupta, Tapan; Lim, T. T.; Chattopadhyay, Manojit

    2000-11-01

    By-pass transition, a phenomenon often encountered in nature and engineering devices, is a complex flow instability caused by moving disturbances over bodies. To date this phenomenon is not fully explained. In the present research a controlled experiment is performed to show that the violent breakdown during by-pass transition is dominated by a two-dimensional mechanism and the resultant broadband energy spectrum of the corresponding turbulent flow is excited at the receptivity stage itself by the primary instability. The experiment is conducted in a water tunnel using dye visualisation technique, and the by-pass transition is created by controlled motion of captive vortices. In the presentation, apart from showing video images of the phenomenon, the similarity of the observed events with secondary instability and fully developed turbulent flows will be discussed.

  18. TRIIODOTHYRONINE INCREASES MYOCARDIAL FUNCTION AND PYRUVATE ENTRY INTO THE CITRIC ACID CYCLE AFTER REPERFUSION IN A MODEL OF INFANT CARDIOPULMONARY BYPASS

    SciTech Connect

    Olson, Aaron; Bouchard, Bertrand; Ning, Xue-Han; Isern, Nancy G.; Des Rosiers, Christine; Portman, Michael A.

    2012-03-01

    We utilized a translational model of infant CPB to test the hypothesis that T3 modulates pyruvate entry into the citric acid cycle (CAC) thereby providing the energy support for improved cardiac function after ischemia-reperfusion. Methods and Results: Neonatal piglets received intracoronary [2-13Carbon(13C)]-pyruvate for 40 minutes (8 mM) during control aerobic conditions (Cont) or immediately after reperfusion (IR) from global hypothermic ischemia. A third group (IR-Tr) received T3 (1.2 ug/kg) during reperfusion. We assessed absolute CAC intermediate levels (aCAC) and flux parameters into the CAC through oxidative pyruvate decarboxylation (PDC ) and anaplerotic carboxylation (PC; ) using 13C-labeled pyruvate and isotopomer analysis by gas and liquid chromatography-mass spectrometry and 13C NMR. Neither IR nor IR-Tr modified aCAC. However, compared to IR, T3 (group IR-Tr) increased cardiac power and oxygen consumption after CPB while elevating both PDC and PC (~ four-fold). T3 inhibited IR induced reductions in CAC intermediate molar percent enrichment (MPE) and oxaloacetate(citrate)/malate MPE ratio; an index of aspartate entry into the CAC. Conclusions: T3 markedly enhances PC and PDC thereby providing substrate for elevated cardiac function and work after reperfusion. The increases in pyruvate flux occur with preservation of the CAC intermediate pool. Additionally, T3 inhibition of reductions in CAC intermediate MPEs indicates that T3 reduces the reliance on amino acids (AA) for anaplerosis after reperfusion. Thus, AA should be more available for other functions such as protein synthesis.

  19. A Method to Predict Compressor Stall in the TF34-100 Turbofan Engine Utilizing Real-Time Performance Data

    DTIC Science & Technology

    2015-06-01

    Douglas Probert, “Detection and Prediction of the Performance Deterioration of a Turbofan Engine”, Proceedings of the International Gas Turbine ...Handbook”, A-10 Turbine Engine Monitor System, for Version 54.1 and 56.1 software, section 3.1.4 VG Schedule. 82 APPENDIX A. THE FORMULA TO

  20. Development and verification of real-time, hybrid computer simulation of F100-PW-100(3) turbofan engine

    NASA Technical Reports Server (NTRS)

    Szuch, J. R.; Seldner, K.; Cwynar, D. S.

    1977-01-01

    A real time, hybrid computer simulation of a turbofan engine is described. Controls research programs involving that engine are supported by the simulation. The real time simulation is shown to match the steady state and transient performance of the engine over a wide range of flight conditions and power settings. The simulation equations, FORTRAN listing, and analog patching diagrams are included.

  1. 77 FR 10355 - Airworthiness Directives; Rolls-Royce plc (RR) RB211-Trent 800 Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-22

    ...-12-AD; Amendment 39-16956; AD 2012-04-01] RIN 2120-AA64 Airworthiness Directives; Rolls-Royce plc (RR...: Final rule. SUMMARY: We are superseding an existing airworthiness directive (AD) for all RR RB211-Trent 800 series turbofan engines. That AD currently requires removal from service of certain...

  2. 76 FR 68663 - Airworthiness Directives; Rolls-Royce plc (RR) RB211-Trent 800 Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-07

    ... Directives; Rolls-Royce plc (RR) RB211-Trent 800 Series Turbofan Engines AGENCY: Federal Aviation..., contact Rolls-Royce plc, Corporate Communications, P.O. Box 31, Derby, England, DE248BJ; phone: 011-44...-Royce plc substantiated their proposed increased life of P/N FK21117 by rig test and analysis. AD...

  3. 75 FR 801 - Airworthiness Directives; Rolls-Royce plc RB211-Trent 500, 700, and 800 Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-06

    ... Federal Aviation Administration 14 CFR Part 39 RIN 2120-AA64 Airworthiness Directives; Rolls-Royce plc... airworthiness directive (AD) for Rolls-Royce plc RB211-Trent 800 series turbofan engines. That AD currently... through Friday, except Federal holidays. Fax: (202) 493-2251. Contact Rolls-Royce plc, P.O. Box 31,...

  4. 75 FR 2064 - Airworthiness Directives; CFM International, S.A. CFM56-7B Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-14

    .... CFM56-7B series turbofan engines. This AD requires initial and repetitive eddy current inspections (ECIs... about 3 work-hours to perform an eddy current inspection of an LP turbine rear frame. The average labor...-258-0; or 340-166-259-0, do the following: (1) Perform an initial eddy current inspection (ECI) of...

  5. Battery Cell By-Pass Circuit

    NASA Technical Reports Server (NTRS)

    Evers, Jeffrey (Inventor); Gelger, Ronald V. (Inventor)

    2001-01-01

    The invention is a circuit and method of limiting the charging current voltage from a power supply net work applied to an individual cell of a plurality of cells making up a battery being charged in series. It is particularly designed for use with batteries that can be damaged by overcharging, such as Lithium-ion type batteries. In detail. the method includes the following steps: 1) sensing the actual voltage level of the individual cell; 2) comparing the actual voltage level of the individual cell with a reference value and providing an error signal representative thereof; and 3) by-passing the charging current around individual cell necessary to keep the individual cell voltage level generally equal a specific voltage level while continuing to charge the remaining cells. Preferably this is accomplished by by-passing the charging current around the individual cell if said actual voltage level is above the specific voltage level and allowing the charging current to the individual cell if the actual voltage level is equal or less than the specific voltage level. In the step of bypassing the charging current, the by-passed current is transferred at a proper voltage level to the power supply. The by-pass circuit a voltage comparison circuit is used to compare the actual voltage level of the individual cell with a reference value and to provide an error signal representative thereof. A third circuit, designed to be responsive to the error signal, is provided for maintaining the individual cell voltage level generally equal to the specific voltage level. Circuitry is provided in the third circuit for bypassing charging current around the individual cell if the actual voltage level is above the specific voltage level and transfers the excess charging current to the power supply net work. The circuitry also allows charging of the individual cell if the actual voltage level is equal or less than the specific voltage level.

  6. [Simplified laparoscopic gastric bypass. Initial experience].

    PubMed

    Hernández-Miguelena, Luis; Maldonado-Vázquez, Angélica; Cortes-Romano, Pablo; Ríos-Cruz, Daniel; Marín-Domínguez, Raúl; Castillo-González, Armando

    2014-01-01

    Antecedentes: la cirugía de la obesidad comprende diversos procedimientos gastrointestinales. El bypass gástrico en Y de Roux es el prototipo de los procedimientos mixtos y el más practicado en el mundo en sus diversas variedades. Una técnica similar y novedosa es la adoptada por Cardoso-Ramos y Galvao denominada "bypass simplificado" que rápidamente se aceptó por la mayor facilidad y resultados muy parecidos a la técnica convencional. Objetivo: describir los resultados a un año del bypass gástrico simplificado para el tratamiento de la obesidad mórbida. Material y métodos: estudio retrospectivo y descriptivo de todos los pacientes a quienes se realizó bypass gástrico de enero de 2008 a julio de 2012, en la clínica de obesidad de un hospital privado de la Ciudad de México. Resultados: se estudiaron 90 pacientes con diagnóstico de obesidad mórbida, con límites de edad de 18 y 65 años, operados para bypass gástrico simplificado. En 10% de los pacientes hubo complicaciones, las más frecuentes fueron: hemorragia y hernia interna. Durante el periodo de estudio la mortalidad fue de 0%. La pérdida de peso promedio a los 12 meses fue de 72.7%. Conclusión: el bypass gástrico simplificado laparoscópico es una cirugía segura, con buenos resultados a mediano plazo, y con una pérdida del exceso de peso adecuada en 71% de los casos.

  7. Bypassing health facilities for childbirth: a multilevel study in three districts of Gujarat, India

    PubMed Central

    Salazar, Mariano; Vora, Kranti; Costa, Ayesha De

    2016-01-01

    Background Bypassing available facilities for childbirth has important implications for maternal health service delivery and human resources within a health system. The results are the additional expenses imposed on the woman and her family, as well as the inefficient use of health system resources. Bypassing often indicates a lack of confidence in the care provided by the facility nearest to the mother, which implies a level of dysfunctionality that the health system needs to address. Over the past decade, India has experienced a steep rise in the proportion of facility births. The initiation of programs promoting facility births resulted in a rise from 39% in 2005 to 85% in 2014. There have been no reports on bypassing facilities for childbirth from India. In the context of steeply rising facility births, it is important to quantify the occurrence of and study the relative contributions of maternal characteristics and facility functionality to bypassing. Objectives 1) To determine the extent of bypassing health facilities for childbirth among rural mothers in three districts of Gujarat, India, 2) to identify associations between the functionality of an obstetric care (OC) facility and it being bypassed, and 3) to assess the relative contribution of maternal and facility characteristics to bypassing. Design A cross-sectional survey of 166 public and private OC facilities reporting ≥30 births in the 3 months before the survey was conducted in three purposively selected districts (Dahod, Sabarkantha, and Surendranagar) in the state of Gujarat, India. Besides information on each facility, data from 946 women giving birth at these facilities were also gathered. Data were analyzed using a multilevel mixed-effects logistic regression model. Results Off all mothers, 37.7% bypassed their nearest facility for childbirth. After adjusting for maternal characteristics, for every one-unit increase in the facility's emergency obstetric care (EmOC) signal functions, the odds

  8. Bypassing health facilities for childbirth: a multilevel study in three districts of Gujarat, India.

    PubMed

    Salazar, Mariano; Vora, Kranti; De Costa, Ayesha

    2016-01-01

    Background Bypassing available facilities for childbirth has important implications for maternal health service delivery and human resources within a health system. The results are the additional expenses imposed on the woman and her family, as well as the inefficient use of health system resources. Bypassing often indicates a lack of confidence in the care provided by the facility nearest to the mother, which implies a level of dysfunctionality that the health system needs to address. Over the past decade, India has experienced a steep rise in the proportion of facility births. The initiation of programs promoting facility births resulted in a rise from 39% in 2005 to 85% in 2014. There have been no reports on bypassing facilities for childbirth from India. In the context of steeply rising facility births, it is important to quantify the occurrence of and study the relative contributions of maternal characteristics and facility functionality to bypassing. Objectives 1) To determine the extent of bypassing health facilities for childbirth among rural mothers in three districts of Gujarat, India, 2) to identify associations between the functionality of an obstetric care (OC) facility and it being bypassed, and 3) to assess the relative contribution of maternal and facility characteristics to bypassing. Design A cross-sectional survey of 166 public and private OC facilities reporting ≥30 births in the 3 months before the survey was conducted in three purposively selected districts (Dahod, Sabarkantha, and Surendranagar) in the state of Gujarat, India. Besides information on each facility, data from 946 women giving birth at these facilities were also gathered. Data were analyzed using a multilevel mixed-effects logistic regression model. Results Off all mothers, 37.7% bypassed their nearest facility for childbirth. After adjusting for maternal characteristics, for every one-unit increase in the facility's emergency obstetric care (EmOC) signal functions, the odds

  9. Multiplexed Predictive Control of a Large Commercial Turbofan Engine

    NASA Technical Reports Server (NTRS)

    Richter, hanz; Singaraju, Anil; Litt, Jonathan S.

    2008-01-01

    Model predictive control is a strategy well-suited to handle the highly complex, nonlinear, uncertain, and constrained dynamics involved in aircraft engine control problems. However, it has thus far been infeasible to implement model predictive control in engine control applications, because of the combination of model complexity and the time allotted for the control update calculation. In this paper, a multiplexed implementation is proposed that dramatically reduces the computational burden of the quadratic programming optimization that must be solved online as part of the model-predictive-control algorithm. Actuator updates are calculated sequentially and cyclically in a multiplexed implementation, as opposed to the simultaneous optimization taking place in conventional model predictive control. Theoretical aspects are discussed based on a nominal model, and actual computational savings are demonstrated using a realistic commercial engine model.

  10. Polymorphous ventricular tachycardia following cardiopulmonary bypass.

    PubMed Central

    Thompson, L. D.; Cohen, A. J.; Bellasis, R. M.

    1996-01-01

    A 62-year-old African-American man who underwent coronary artery bypass surgery was found to have repetitive ventricular tachycardia of the "Torsade des pointes" type. The arrhythmia was resistant to bretylium, lidocaine, and pacing, but was controlled by intravenous magnesium sulfate. The recurrent attacks were abolished by a bolus of 1 g magnesium sulfate and controlled using a 1 mg/minute drip for 12 hours. This case shows the effectiveness of intravenous magnesium in controlling Torsade des pointes in postoperative coronary bypass patients. PMID:8583493

  11. A Comparison of Hybrid Approaches for Turbofan Engine Gas Path Fault Diagnosis

    NASA Astrophysics Data System (ADS)

    Lu, Feng; Wang, Yafan; Huang, Jinquan; Wang, Qihang

    2016-09-01

    A hybrid diagnostic method utilizing Extended Kalman Filter (EKF) and Adaptive Genetic Algorithm (AGA) is presented for performance degradation estimation and sensor anomaly detection of turbofan engine. The EKF is used to estimate engine component performance degradation for gas path fault diagnosis. The AGA is introduced in the integrated architecture and applied for sensor bias detection. The contributions of this work are the comparisons of Kalman Filters (KF)-AGA algorithms and Neural Networks (NN)-AGA algorithms with a unified framework for gas path fault diagnosis. The NN needs to be trained off-line with a large number of prior fault mode data. When new fault mode occurs, estimation accuracy by the NN evidently decreases. However, the application of the Linearized Kalman Filter (LKF) and EKF will not be restricted in such case. The crossover factor and the mutation factor are adapted to the fitness function at each generation in the AGA, and it consumes less time to search for the optimal sensor bias value compared to the Genetic Algorithm (GA). In a word, we conclude that the hybrid EKF-AGA algorithm is the best choice for gas path fault diagnosis of turbofan engine among the algorithms discussed.

  12. Demonstration of a Packaged Capacitive Pressure Sensor System Suitable for Jet Turbofan Engine Health Monitoring

    NASA Technical Reports Server (NTRS)

    Scardelletti, Maximilian C.; Jordan, Jennifer L.; Meredith, Roger D.; Harsh, Kevin; Pilant, Evan; Usrey, Michael W.; Beheim, Glenn M.; Hunter, Gary W.; Zorman, Christian A.

    2016-01-01

    In this paper, the development and characterization of a packaged pressure sensor system suitable for jet engine health monitoring is demonstrated. The sensing system operates from 97 to 117 MHz over a pressure range from 0 to 350 psi and a temperature range from 25 to 500 deg. The sensing system consists of a Clapp-type oscillator that is fabricated on an alumina substrate and is comprised of a Cree SiC MESFET, MIM capacitors, a wire-wound inductor, chip resistors and a SiCN capacitive pressure sensor. The pressure sensor is located in the LC tank circuit of the oscillator so that a change in pressure causes a change in capacitance, thus changing the resonant frequency of the sensing system. The chip resistors, wire-wound inductors and MIM capacitors have all been characterized at temperature and operational frequency, and perform with less than 5% variance in electrical performance. The measured capacitive pressure sensing system agrees very well with simulated results. The packaged pressure sensing system is specifically designed to measure the pressure on a jet turbofan engine. The packaged system can be installed by way of borescope plug adaptor fitted to a borescope port exposed to the gas path of a turbofan engine.

  13. Acoustic scattering by a spliced turbofan inlet duct liner at supersonic fan speeds

    NASA Astrophysics Data System (ADS)

    McAlpine, A.; Wright, M. C. M.

    2006-05-01

    Fan noise is one of the principal noise sources generated by a turbofan aero-engine. At supersonic fan speeds, fan tones are generated by the "rotor-alone" pressure field. In general, these tones can be well absorbed by an inlet duct acoustic liner, apart from at high supersonic fan speeds. However, in practice inlet duct liners contain acoustically hard longitudinal splices which cause scattering. This leads to acoustic energy being scattered into a range of different azimuthal mode orders, similar to the modal content resulting from rotor-stator interactions. The effectiveness of an inlet duct lining is reduced because acoustic energy is scattered into modes that are poorly absorbed by the liner. In this article, the effect of this acoustic scattering is examined by three-dimensional finite-element simulations of sound transmission in a turbofan inlet duct. Results include predictions of the sound power transmission loss with different splice widths, and at different supersonic fan speeds. These results demonstrate how acoustic scattering by liner splices can adversely affect fan tone noise levels at low supersonic fan speeds, but have little adverse affect on noise levels at high supersonic fan speeds. The potential noise benefit that could be achieved by manufacturing thinner splices is also examined.

  14. Variable volume combustor with an air bypass system

    DOEpatents

    Johnson, Thomas Edward; Ziminsky, Willy Steve; Ostebee, Heath Michael; Keener, Christopher Paul

    2017-02-07

    The present application provides a combustor for use with flow of fuel and a flow of air in a gas turbine engine. The combustor may include a number of micro-mixer fuel nozzles positioned within a liner and an air bypass system position about the liner. The air bypass system variably allows a bypass portion of the flow of air to bypass the micro-mixer fuel nozzles.

  15. Investigation on the Core Bypass Flow in a Very High Temperature Reactor

    SciTech Connect

    Hassan, Yassin

    2013-10-22

    Uncertainties associated with the core bypass flow are some of the key issues that directly influence the coolant mass flow distribution and magnitude, and thus the operational core temperature profiles, in the very high-temperature reactor (VHTR). Designers will attempt to configure the core geometry so the core cooling flow rate magnitude and distribution conform to the design values. The objective of this project is to study the bypass flow both experimentally and computationally. Researchers will develop experimental data using state-of-the-art particle image velocimetry in a small test facility. The team will attempt to obtain full field temperature distribution using racks of thermocouples. The experimental data are intended to benchmark computational fluid dynamics (CFD) codes by providing detailed information. These experimental data are urgently needed for validation of the CFD codes. The following are the project tasks: • Construct a small-scale bench-top experiment to resemble the bypass flow between the graphite blocks, varying parameters to address their impact on bypass flow. Wall roughness of the graphite block walls, spacing between the blocks, and temperature of the blocks are some of the parameters to be tested. • Perform CFD to evaluate pre- and post-test calculations and turbulence models, including sensitivity studies to achieve high accuracy. • Develop the state-of-the art large eddy simulation (LES) using appropriate subgrid modeling. • Develop models to be used in systems thermal hydraulics codes to account and estimate the bypass flows. These computer programs include, among others, RELAP3D, MELCOR, GAMMA, and GAS-NET. Actual core bypass flow rate may vary considerably from the design value. Although the uncertainty of the bypass flow rate is not known, some sources have stated that the bypass flow rates in the Fort St. Vrain reactor were between 8 and 25 percent of the total reactor mass flow rate. If bypass flow rates are on the

  16. Massive sediment bypassing on the lower shoreface offshore of a wide tidal inlet - Cat Island Pass, Louisiana

    USGS Publications Warehouse

    Jaffe, B.E.; List, J.H.; Sallenger, A.H.

    1997-01-01

    Analysis of a series of historical bathymetric and shoreline surveys along the Louisiana coast west of the Mississippi River mouth detected a large area of deposition in water depths of 2.0-8.5 m offshore of a 9-km- wide tidal inlet, the Cat Island Pass/Wine Island Pass system. A 59.9 ?? 106 m3 sandy deposit formed from the 1930s-1980s, spanning 27 km in the alongshore direction, delineating the transport pathway for sediment bypassing offshore of the inlet on the shoreface. Bypassing connected the shorefaces of two barrier island systems, the Isles Dernieres and the Bayou Lafourche. The processes responsible for formation of this deposit are not well understood, but sediment-transport modeling suggests that sediment is transported primarily by wind-driven coastal currents during large storms and hurricanes. Deposition appears to be related to changes in shoreline orientation, closing of transport pathways into a large bay to the east and the presence of tidal inlets. This newly documented type of bypassing, an offshore bypassing of the inlet system, naturally nourished the immediate downdrift area, the eastern Isles Dernieres, where shoreface and shoreline erosion rates are about half of pre-bypassing rates. Erosion rates remained the same farther downdrift, where bypassing has not yet reached. As this offshore bypassing continues, the destruction of the Isles Dernieres will be slowed.

  17. 21 CFR 870.4390 - Cardiopulmonary bypass pump tubing.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Cardiopulmonary bypass pump tubing. 870.4390... bypass pump tubing. (a) Identification. A cardiopulmonary bypass pump tubing is polymeric tubing which is used in the blood pump head and which is cyclically compressed by the pump to cause the blood to...

  18. 21 CFR 870.4390 - Cardiopulmonary bypass pump tubing.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Cardiopulmonary bypass pump tubing. 870.4390... bypass pump tubing. (a) Identification. A cardiopulmonary bypass pump tubing is polymeric tubing which is used in the blood pump head and which is cyclically compressed by the pump to cause the blood to...

  19. 21 CFR 870.4390 - Cardiopulmonary bypass pump tubing.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Cardiopulmonary bypass pump tubing. 870.4390... bypass pump tubing. (a) Identification. A cardiopulmonary bypass pump tubing is polymeric tubing which is used in the blood pump head and which is cyclically compressed by the pump to cause the blood to...

  20. 21 CFR 870.4390 - Cardiopulmonary bypass pump tubing.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Cardiopulmonary bypass pump tubing. 870.4390... bypass pump tubing. (a) Identification. A cardiopulmonary bypass pump tubing is polymeric tubing which is used in the blood pump head and which is cyclically compressed by the pump to cause the blood to...

  1. Bypass apparatus and method for series connected energy storage devices

    DOEpatents

    Rouillard, Jean; Comte, Christophe; Daigle, Dominik

    2000-01-01

    A bypass apparatus and method for series connected energy storage devices. Each of the energy storage devices coupled to a common series connection has an associated bypass unit connected thereto in parallel. A current bypass unit includes a sensor which is coupled in parallel with an associated energy storage device or cell and senses an energy parameter indicative of an energy state of the cell, such as cell voltage. A bypass switch is coupled in parallel with the energy storage cell and operable between a non-activated state and an activated state. The bypass switch, when in the non-activated state, is substantially non-conductive with respect to current passing through the energy storage cell and, when in the activated state, provides a bypass current path for passing current to the series connection so as to bypass the associated cell. A controller controls activation of the bypass switch in response to the voltage of the cell deviating from a pre-established voltage setpoint. The controller may be included within the bypass unit or be disposed on a control platform external to the bypass unit. The bypass switch may, when activated, establish a permanent or a temporary bypass current path.

  2. 30 CFR 57.19018 - Overtravel by-pass switches.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Overtravel by-pass switches. 57.19018 Section... Hoisting Hoists § 57.19018 Overtravel by-pass switches. When an overtravel by-pass switch is installed, the switch shall function so as to allow the conveyance to be moved through the overtravel position when...

  3. 30 CFR 56.19018 - Overtravel by-pass switches.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Overtravel by-pass switches. 56.19018 Section... Hoisting Hoists § 56.19018 Overtravel by-pass switches. When an overtravel by-pass switch is installed, the switch shall function so as to allow the conveyance to be moved through the overtravel position when...

  4. 30 CFR 56.19018 - Overtravel by-pass switches.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Overtravel by-pass switches. 56.19018 Section... Hoisting Hoists § 56.19018 Overtravel by-pass switches. When an overtravel by-pass switch is installed, the switch shall function so as to allow the conveyance to be moved through the overtravel position when...

  5. 30 CFR 57.19018 - Overtravel by-pass switches.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Overtravel by-pass switches. 57.19018 Section... Hoisting Hoists § 57.19018 Overtravel by-pass switches. When an overtravel by-pass switch is installed, the switch shall function so as to allow the conveyance to be moved through the overtravel position when...

  6. 30 CFR 56.19018 - Overtravel by-pass switches.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Overtravel by-pass switches. 56.19018 Section... Hoisting Hoists § 56.19018 Overtravel by-pass switches. When an overtravel by-pass switch is installed, the switch shall function so as to allow the conveyance to be moved through the overtravel position when...

  7. 30 CFR 57.19018 - Overtravel by-pass switches.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Overtravel by-pass switches. 57.19018 Section... Hoisting Hoists § 57.19018 Overtravel by-pass switches. When an overtravel by-pass switch is installed, the switch shall function so as to allow the conveyance to be moved through the overtravel position when...

  8. 21 CFR 870.4250 - Cardiopulmonary bypass temperature controller.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Cardiopulmonary bypass temperature controller. 870... Cardiopulmonary bypass temperature controller. (a) Identification. A cardiopulmonary bypass temperature controller is a device used to control the temperature of the fluid entering and leaving a heat exchanger....

  9. 21 CFR 870.4250 - Cardiopulmonary bypass temperature controller.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Cardiopulmonary bypass temperature controller. 870... Cardiopulmonary bypass temperature controller. (a) Identification. A cardiopulmonary bypass temperature controller is a device used to control the temperature of the fluid entering and leaving a heat exchanger....

  10. 21 CFR 870.4250 - Cardiopulmonary bypass temperature controller.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cardiopulmonary bypass temperature controller. 870... Cardiopulmonary bypass temperature controller. (a) Identification. A cardiopulmonary bypass temperature controller is a device used to control the temperature of the fluid entering and leaving a heat exchanger....

  11. 21 CFR 870.4250 - Cardiopulmonary bypass temperature controller.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Cardiopulmonary bypass temperature controller. 870... Cardiopulmonary bypass temperature controller. (a) Identification. A cardiopulmonary bypass temperature controller is a device used to control the temperature of the fluid entering and leaving a heat exchanger....

  12. 21 CFR 870.4250 - Cardiopulmonary bypass temperature controller.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Cardiopulmonary bypass temperature controller. 870... Cardiopulmonary bypass temperature controller. (a) Identification. A cardiopulmonary bypass temperature controller is a device used to control the temperature of the fluid entering and leaving a heat exchanger....

  13. 21 CFR 870.4400 - Cardiopulmonary bypass blood reservoir.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cardiopulmonary bypass blood reservoir. 870.4400... bypass blood reservoir. (a) Identification. A cardiopulmonary bypass blood reservoir is a device used in conjunction with short-term extracorporeal circulation devices to hold a reserve supply of blood in the...

  14. 21 CFR 870.4240 - Cardiopulmonary bypass heat exchanger.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Cardiopulmonary bypass heat exchanger. 870.4240... bypass heat exchanger. (a) Identification. A cardiopulmonary bypass heat exchanger is a device, consisting of a heat exchange system used in extracorporeal circulation to warm or cool the blood...

  15. 21 CFR 870.4240 - Cardiopulmonary bypass heat exchanger.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cardiopulmonary bypass heat exchanger. 870.4240... bypass heat exchanger. (a) Identification. A cardiopulmonary bypass heat exchanger is a device, consisting of a heat exchange system used in extracorporeal circulation to warm or cool the blood...

  16. 20 CFR 631.18 - Federal by-pass authority.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Federal by-pass authority. 631.18 Section 631... Procedures § 631.18 Federal by-pass authority. (a) In the event that a State fails to submit a biennial State... Secretary's intent to exercise by-pass authority and an opportunity to request and to receive a...

  17. 21 CFR 870.4400 - Cardiopulmonary bypass blood reservoir.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Cardiopulmonary bypass blood reservoir. 870.4400... bypass blood reservoir. (a) Identification. A cardiopulmonary bypass blood reservoir is a device used in... circulation. (b) Classification. Class II (performance standards), except that a reservoir that contains...

  18. 21 CFR 870.4400 - Cardiopulmonary bypass blood reservoir.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Cardiopulmonary bypass blood reservoir. 870.4400... bypass blood reservoir. (a) Identification. A cardiopulmonary bypass blood reservoir is a device used in... circulation. (b) Classification. Class II (performance standards), except that a reservoir that contains...

  19. 21 CFR 870.4400 - Cardiopulmonary bypass blood reservoir.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Cardiopulmonary bypass blood reservoir. 870.4400... bypass blood reservoir. (a) Identification. A cardiopulmonary bypass blood reservoir is a device used in... circulation. (b) Classification. Class II (performance standards), except that a reservoir that contains...

  20. 21 CFR 870.4400 - Cardiopulmonary bypass blood reservoir.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Cardiopulmonary bypass blood reservoir. 870.4400... bypass blood reservoir. (a) Identification. A cardiopulmonary bypass blood reservoir is a device used in... circulation. (b) Classification. Class II (performance standards), except that a reservoir that contains...