Science.gov

Sample records for adjusting blade angle

  1. Research on Optimal Operation by Adjusting Blade Angle in Jiangdu No. 4 Pumping Station of China

    NASA Astrophysics Data System (ADS)

    Lihua, Zhang; Jilin, Chang; Rentian, Zhang; Yi, Gong

    2010-06-01

    A Nonlinear Programming Model for the optimal day-operation of multi-units pump in one pumping station by adjusting blade angle has been put out, where the peak-valley electricity prices is considered in this paper. The model takes the minimal operation cost of pump assembly as objective function. In the meantime, the periods are defined as stage variables. The blade angle and the number of the working-pumps are expressed as decision variables and the water volume pumped in one day as constraint condition. The problem is very difficult to be settled by regular methods. This paper presents a new method which adopts experimental optimization method of adjusting blade angle in different periods and linear integral programming method to select the number of pumps. After applying the method to the optimal operation of Jiangdu No.4 pumping station, which is the source pump station of Eastern Route Project of South-to-North Water Diversion(Where there are seven pumps and the design flow rate of single-unit is 30.0m3/sec), we get the results which are as follows:(1) With the constraint conditions of typical tidal process which are average tidal levels from December to February of next year, designed average pumping head of 7.8m, and the operation load at 100%,80%,60% of full-load(the water volume when the pumps working with the blade angle of 0 degree and the speed of 150r/min in full day), the relative energy-saving reaches 5.18%˜33.02% comparing with the state of keeping the pump operating at its designed blade angle which is 0 degree when considering peak-valley electricity prices. While not considering the peak-valley electricity prices, the number is 1.96%˜9.71%, and less load corresponds to more cost-saving. (2) The key factory on deciding the operation state of pumps is electricity price when we consider the peak-valley electricity prices. All the pumps should be working and the blade angle should be in the largest state when at the valley price, while the number

  2. Reduction of blade passage tone by angle modulation

    NASA Astrophysics Data System (ADS)

    Fiagbedzi, Y. A.

    1982-05-01

    Blade staggering has been used in both centrifugal and axial flow fans to reduce discrete tones. Impeller hub resilience, causing fan torsional oscillations, appears to be equivalent to blade staggering in that both lead to angle modulation of the blade passage sound. By using Jacobi-Anger expansions, the sound reductions resulting from the angle modulation effects of these two equivalent techniques are predicted. Excellent agreement is found with published data.

  3. Extension of Useful Operating Range of Axial-Flow Compressors by Use of Adjustable Stator Blades

    NASA Technical Reports Server (NTRS)

    Sinnette, John T; Voss, William J

    1948-01-01

    A theory has been developed for resetting the blade angles of an axial-flow compressor in order to improve the performance at speeds and flows other than the design and thus extend the useful operating range of the compressor. The theory is readily applicable to the resetting of both rotor and stator blades or to the resetting of only the stator blades and is based on adjustment of the blade angles to obtain lift coefficients at which the blades will operate efficiently. Calculations were made for resetting the stator blades of the NACA eight-stage axial-flow compressor for 75 percent of design speed and a series of load coefficients ranging from 0.28 to 0.70 with rotor blades left at the design setting. The NACA compressor was investigated with three different blade settings: (1) the design blade setting, (2) the stator blades reset for 75 percent of design speed and a load coefficient of 0.48, and (3) the stator blades reset for 75 percent of design speed and a load coefficient of 0.65.

  4. Adjustable-Angle Drill Block

    NASA Technical Reports Server (NTRS)

    Gallimore, F. H.

    1986-01-01

    Adjustable angular drill block accurately transfers hole patterns from mating surfaces not normal to each other. Block applicable to transfer of nonperpendicular holes in mating contoured assemblies in aircraft industry. Also useful in general manufacturing to transfer mating installation holes to irregular and angular surfaces.

  5. Simulations of Blade Angle Effects on EGAT-Micro Hydro Turbine

    NASA Astrophysics Data System (ADS)

    Nuantong, Weerapon; Taechajedcadarungsri, Sirivit

    2010-06-01

    Following the feasibility study of design phase of EGAT (Electricity Generating Authority of Thailand) in-house micro hydro bulb turbine at Huai Kum Dam drainage pipeline from the reservoir for irrigation, the simulation of blade angle effects had been performed. In this case study, the turbine was designed at the average head of 21 m and water flow rate of 0.424 m3/s. The simulation was conducted in order to study of the effects of blade angle on the fluid flow for this specific case. The LES turbulence model under the practical condition of unsteady flow and incompressible fluid at Huai Kum Dam was investigated. The rotating blades effect the change in pressure and momentum which depend on head and flow rate of fluid. The research studied pressure and velocity of fluid flow on blades solving the pre-design for the improvement of hydro turbine efficiency. The computational Fluid Dynamics (CFD) was used to simulate the pressure and velocity distributions on blades of hydro bulb turbine which consists of five-blade runner and rotates at 980 rpm by using Fluent Software. The model was set at the blade twist angle of 25o and blade camber angle of 32o and then adjusted the guide vane angle to 60o, 65o and 70o respectively for comparing the maximum and minimum pressure on both sides of the blades as well as the corresponding efficiency. The results have shown that by setting guide vane angle to 60o, 65o and 70o, the maximum pressure, located at the leading edge of pressure side, are 213 kPa, 217 kPa and 207 kPa and the minimum pressure, located at the leading edge of suction side are -473 kPa, -465 kPa, and -581 kPa respectively. The flow profiles of pressure, velocity and stream line showed the guidelines of better blade angle comparisons. The maximum efficiency of hydro bulb turbine found in this study was 67.8% at blade angle of 32o and guide vane of 60o. This case study will be further investigated on the blade design for the improvement of the turbine efficiency

  6. Effect of blade outlet angle on radial thrust of single-blade centrifugal pump

    NASA Astrophysics Data System (ADS)

    Nishi, Y.; Fukutomi, J.; Fujiwara, R.

    2012-11-01

    Single-blade centrifugal pumps are widely used as sewage pumps. However, a large radial thrust acts on a single blade during pump operation because of the geometrical axial asymmetry of the impeller. This radial thrust causes vibrations of the pump shaft, reducing the service life of bearings and shaft seal devices. Therefore, to ensure pump reliability, it is necessary to quantitatively understand the radial thrust and clarify the behavior and generation mechanism. This study investigated the radial thrust acting on two kinds of single-blade centrifugal impellers having different blade outlet angles by experiments and computational fluid dynamics (CFD) analysis. Furthermore, the radial thrust was modeled by a combination of three components, inertia, momentum, and pressure, by applying an unsteady conservation of momentum to this impeller. As a result, the effects of the blade outlet angle on both the radial thrust and the modeled components were clarified. The total head of the impeller with a blade outlet angle of 16 degrees increases more than the impeller with a blade outlet angle of 8 degrees at a large flow rate. In this case, since the static pressure of the circumference of the impeller increases uniformly, the time-averaged value of the radial thrust of both impellers does not change at every flow rate. On the other hand, since the impeller blade loading becomes large, the fluctuation component of the radial thrust of the impeller with the blade outlet angle of 16 degrees increases. If the blade outlet angle increases, the fluctuation component of the inertia component will increase, but the time-averaged value of the inertia component is located near the origin despite changes in the flow rate. The fluctuation component of the momentum component becomes large at all flow rates. Furthermore, although the time-averaged value of the pressure component is almost constant, the fluctuation component of the pressure component becomes large at a large flow rate

  7. Sensor for measuring instantaneous angle of attack of helicopter blades

    NASA Technical Reports Server (NTRS)

    Barna, P. S.

    1980-01-01

    Systematic investigations were performed on a variety of probes to determine their potential for possible application as sensors attached to helicopter blades to measure both the instantaneous angle of attack as well as the dynamic head during actual flight operations. After some preliminary considerations a sensor of essentially spherical shape, about 30 mm in diameter, was designed. The sensor was provided with three pressure ports, and it housed two pressure transducers required for sensing the prevailing pressures acting outside on the surface. The sensors were subsequently tested in the laboratory under a variety of flow conditions to determine their aerodynamic characteristics. Two series of tests were performed: in the first series the sensor was fixed in space while exposed to steady uniform flow, while in the second series the sensor was made to oscillate, thus simulating the cyclic pitch change of the helicopter blades. While the cyclic pitch frequencies were of about the same magnitude as encountered in flight, the flow velocities during tests fell well below those experienced in a rotating blade. The tests showed that the sensors performed satisfactorily under low subsonic flow conditions with frequencies not exceeding five Hz.

  8. Performance of Typical Rear-Stage Axial-Flow Compressor Rotor Blade Row at Three Different Blade Setting Angles

    NASA Technical Reports Server (NTRS)

    Kussoy, Marvin I.; Bachkin, Daniel

    1959-01-01

    A comparison of the performance of a single-stage rotor run at three different blade setting angles is presented. The rotor was of a design typical for a last stage of a multistage compressor. At each setting angle, the rotor blade row was operated from 53 to 100 percent of equivalent maximum speed (850 ft/sec tip speed) at constant inlet pressure. Hot-wire anemometry was used to observe rotating-stall and surge patterns in time unsteady flow. Results indicated that an increase in peak pressure ratio and an increase in maximum equivalent weight flow were obtained at each speed investigated when the blade setting angle was decreased. An increase in peak efficiency was achieved with decrease in blade setting angle for part of the range of speeds investigated. However, the peak efficiencies for the three blade setting angles were approximately the same at the maximum speed investigated. The flow ranges for all three configurations were about the same at minimum speed and decreased at almost the same rate when the rotative speed was increased through part of the range of speeds investigated. At maximum speed, the flow range for the smallest setting angle was considerably less than the flow range for the other two configurations. A decrease in efficiency and flow range for the smallest blade setting angle at maximum speed can be attributed primarily to a Mach number effect. In addition, because of the difference in projected axial chord lengths at the casing wall, some effect on performance could be expected from the change in three-dimensional flow occurring at the tip. Rotating-stall characteristics for the two smaller blade setting angles were essentially the same. Only surge could be detected for the largest blade setting angle in the unstable-flow region of operation.

  9. Improved blade profile loss and deviation angle models for advanced transonic compressor bladings. Part 2: A model for supersonic flow

    SciTech Connect

    Koenig, W.M.; Hennecke, D.K.; Fottner, L.

    1996-01-01

    New blading concepts as used in modern transonic axial-flow compressors require improved loss and deviation angle correlations. The new model presented in this paper incorporates several elements and treats blade-row flows having subsonic and supersonic inlet conditions separately. The second part of the present report focuses on the extension of a well-known correlation for cascade losses at supersonic inlet flows. It was originally established for DCA bladings and is now modified to reflect the flow situation in blade rows having low-cambered, arbitrarily designed blades including precompression blades. Finally, the steady loss increase from subsonic to supersonic inlet-flow velocities demonstrates the matched performance of the different correlations of the new model.

  10. Dynamically Adjustable Wind Turbine Blades: Adaptive Turbine Blades, Blown Wing Technology for Low-Cost Wind Power

    SciTech Connect

    2010-02-02

    Broad Funding Opportunity Announcement Project: Caitin is developing wind turbines with a control system that delivers compressed air from special slots located in the surface of its blades. The compressed air dynamically adjusts the aerodynamic performance of the blades, and can essentially be used to control lift, drag, and ultimately power. This control system has been shown to exhibit high levels of control in combination with an exceptionally fast response rate. The deployment of such a control system in modern wind turbines would lead to better management of the load on the system during peak usage, allowing larger blades to be deployed with a resulting increase in energy production.

  11. Compressor blade setting angle accuracy study, volume 1

    NASA Technical Reports Server (NTRS)

    Holman, F. F.; Kidwell, J. R.

    1976-01-01

    The aerodynamic test of a small, single stage, highly loaded, axial flow transonic compressor is covered. The stage was modified by fabricating a 24 blade rotor with mis-set blades in a repeating pattern - two degrees closed from nominal, two degrees open from nominal and nominal. The unit was instrumented to determine overall performance and average blade element data. High-response, dynamic pressure probes were installed to record pressure patterns at selected points in the flowpath. Testing was conducted at speeds from 70 to 94% of design equivalent speed with a conventional casing and also with circumferential grooves over the rotor tip. Testing indicated severe performance penalties were incurred as a result of the mis-set blading. Lower flow, pressure ratio, and efficiency were observed for the stage with or without casing treatment. Periodic pressure variations were detected at every location where high response pressure sensors were located and were directly related to blading geometry.

  12. Influence of blade outlet angle on performance of low-specific-speed centrifugal pump

    NASA Astrophysics Data System (ADS)

    Cui, Baoling; Wang, Canfei; Zhu, Zuchao; Jin, Yingzi

    2013-04-01

    In order to analyze the influence of blade outlet angle on inner flow field and performance of low-specific-speed centrifugal pump, the flow field in the pump with different blade outlet angles 32.5° and 39° was numerically calculated. The external performance experiment was also carried out on the pump. Based on SIMPLEC algorithm, time-average N-S equation and the rectified k-ɛ turbulent model were adopted during the process of computation. The distributions of velocity and pressure in pumps with different blade outlet angles were obtained by calculation. The numerical results show that backflow areas exist in the two impellers, while the inner flow has a little improvement in the impeller with larger blade outlet angle. Blade outlet angle has a certain influence on the static pressure near the long-blade leading edge and tongue, but it has little influence on the distribution of static pressure in the passages of impeller. The experiment results show that the low-specific-speed centrifugal pump with larger blade outlet angle has better hydraulic performance.

  13. Improved blade profile loss and deviation angle models for advanced transonic compressor bladings. Part 1: A model for subsonic flow

    SciTech Connect

    Koenig, W.M.; Hennecke, D.K.; Fottner, L.

    1996-01-01

    New blading concepts as used in modern transonic axial-flow compressors require improved loss and deviation angle correlations. The new model presented in this paper incorporates several elements and treats blade-row flows having subsonic and supersonic inlet conditions separately. In the first part of this paper two proved and well-established profile loss correlations for subsonic flows are extended to quasi-two-dimensional conditions and to custom-tailored blade designs. Instead of a deviation angle correlation, a simple method based on singularities is utilized. The comparison between the new model and a recently published model demonstrates the improved accuracy in prediction of cascade performance achieved by the new model.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  15. Dependence of propeller efficiency on angle of attack of propeller blade

    NASA Technical Reports Server (NTRS)

    Borck, Hermann

    1921-01-01

    In order to determine the maximum and the most favorable pitch for a propeller, it was found desirable to investigate the dependence of propeller efficiency on the angle of attack of the propeller blade. The results of a few experiments are given to show that propeller blades conduct themselves just like airplane wings with reference to the dependence of their efficiency on their angle of attack.

  16. Supracondylar Osteotomy in Valgus Knee: Angle Blade Plate Versus Locking Compression Plate

    PubMed Central

    Kazemi, Seyyed Morteza; Minaei, Reza; Safdari, Farshad; Keipourfard, Ali; Forghani, Rozhin; Mirzapourshafiei, Alemeh

    2016-01-01

    Background: There are few studies comparing the biomechanical properties of angled blade plate and locking compression plates in supracondylar osteotomy. In the current randomized study, we prospectively compared the clinical and radiological outcomes of supracondylar osteotomy using these two plates. Methods: Forty patients with valgus knee malalignment were randomly assigned to two equal numbered groups: angled blade plate and locking compression plates. All of the patients underwent medial closing wedge supracondylar osteotomy and were followed for one year. Before and after the operation the valgus angle and mechanical lateral distal femoral angle were compared between groups. Also, the rate of complications were compared. Results: After the operation, the mean valgus angle and mechanical lateral distal femoral angle improved significantly in the two groups (P<0.001). Although, the preoperative amount of the valgus angle and mechanical lateral distal femoral angle were the same, at the last visit the valgus angle (5.4±2.1 versus 3.1±1.8; P=0.032) and mechanical lateral distal femoral angle (87.6±2 versus 89.7±3.2; P=0.041) were significantly lower and higher in the angled blade plate group, respectively. Nonunion occurred in four patients (20%) in the locking compression plates group (P=0.35). Conclusion: Based on having a larger valgus angle and mechanical lateral distal femoral angle correction in the angled blade plate group and considerable rate of nonunion in the locking compression plate group, the authors recommend using the angled blade plate for fixation of medial closing wedge supracondylar osteotomy for patients with valgus malalignment. However, more long-term studies are required. PMID:26894215

  17. Investigation of Blade Angle of an Open Cross-Flow Runner

    NASA Astrophysics Data System (ADS)

    Katayama, Yusuke; Iio, Shouichiro; Veerapun, Salisa; Uchiyama, Tomomi

    2015-04-01

    The aim of this study was to develop a nano-hydraulic turbine utilizing drop structure in irrigation channels or industrial waterways. This study was focused on an open-type cross-flow turbine without any attached equipment for cost reduction and easy maintenance. In this study, the authors used an artificial indoor waterfall as lab model. Test runner which is a simple structure of 20 circular arc-shaped blades sandwiched by two circular plates was used The optimum inlet blade angle and the relationship between the power performance and the flow rate approaching theoretically and experimentally were investigated. As a result, the optimum inlet blade angle due to the flow rate was changed. Additionally, allocation rate of power output in 1st stage and 2nd stage is changed by the blade inlet angle.

  18. Effect of Load Phase Angle on Wind Turbine Blade Fatigue Damage: Preprint

    SciTech Connect

    White, D. L.; Musial, W. D.

    2003-11-01

    This paper examines the importance of phase angle variations with respect to fatigue damage. The operating loads on a generic conventional three-bladed upwind 1.5-MW wind turbine blade were analyzed over a range of operating conditions, and an aggregate probability distribution for the actual phase angles between the in-plane (lead-lag) and out-of-plane (flap) loads was determined. Using a finite element model of a generic blade and Miner's Rule, the accumulated theoretical damage (based on axial strains) resulting from a fatigue test with variable phase angles was compared to the damage resulting from a fatigue test with a constant phase angle. The nodal damage distribution at specific blade cross-sections are compared for the constant and variable phase angle cases. The sequence effects of various phase angle progressions were also considered. For this analysis, the finite element results were processed using the nonlinear Marco-Starkey damage accumulation model. Each phase angle sequence was constrained to have the same overall phase angle distribution and the same total number of cycles but the order in which the phase angles were applied was varied.

  19. Prediction of Unsteady Blade Surface Pressures on an Advanced Propeller at an Angle of Attack

    NASA Technical Reports Server (NTRS)

    Nallasamy, M.; Groeneweg, J. F.

    1989-01-01

    The numerical solution of the unsteady, three-dimensional, Euler equations is considered in order to obtain the blade surface pressures of an advanced propeller at an angle of attack. The specific configuration considered is the SR7L propeller at cruise conditions with a 4.6 deg inflow angle corresponding to the plus 2 deg nacelle tilt of the Propeller Test Assessment (PTA) flight test condition. The results indicate nearly sinusoidal response of the blade loading, with angle of attack. For the first time, detailed variations of the chordwise loading as a function of azimuthal angle are presented. It is observed that the blade is lightly loaded for part of the revolution and shocks appear from hub to about 80 percent radial station for the highly loaded portion of the revolution.

  20. Prediction of unsteady blade surface pressures on an advanced propeller at an angle of attack

    NASA Technical Reports Server (NTRS)

    Nallasamy, M.; Groeneweg, J. F.

    1989-01-01

    The paper considers the numerical solution of the unsteady, three-dimensional, Euler equations to obtain the blade surface pressures of an advanced propeller at an angle of attack. The specific configuration considered is the SR7L propeller at cruise conditions with a 4.6 deg inflow angle corresponding to the +2 deg nacelle tilt of the Propeller Test Assessment (PTA) flight test condition. The results indicate nearly sinusoidal response of the blade loading, with angle of attack. For the first time, detailed variations of the chordwise loading as a function of azimuthal angle are presented. It is observed that the blade is lightly loaded for part of the revolution and shocks appear from hub to about 80 percent radial station for the highly loaded portion of the revolution.

  1. Estimation of deviation angle for axial-flow compressor blade sections using inviscid-flow solutions

    NASA Technical Reports Server (NTRS)

    Miller, M. J.

    1974-01-01

    Development of a method of estimating deviation angles by analytical procedures was begun. Solutions for inviscid, irrotational flow in the blade-to-blade plane were obtained with a finite-difference calculation method. Deviation angles for a plane cascade with a rounded trailing edge were estimated by using the inviscid-flow solutions and three trailing-edge hypotheses. The estimated deviation angles were compared with existing experimental data over a range of incidence angles at inlet flow angles of 30 deg and 60 deg. The results indicate that deviation angles can be estimated accurately (within 1 deg) by using one of the three trailing-edge hypotheses, but only when pressure losses are low. A new trailing-edge hypotheses is presented which is suitable (for the cascade considered) for both low- and high-loss operating points.

  2. Introducing an Angle Adjustable Cutting Box for Analyzing Slice Shear Force in Meat

    PubMed Central

    Whitesell, Tom; Avilés, Carmen; Aalhus, Jennifer L.; Calkins, Chris R.; Larsen, Ivy L.; Juárez, Manuel

    2013-01-01

    Research indicates the fibre angle of the longissimus muscle can vary, depending upon location within a steak and throughout the muscle. Instead of using the original fixed 45 ° or 90 ° cutting angle for testing shear force, a variable angle cutting box can be adjusted so the angles of the knives correspond to the fibre angle of each sample. Within 2 min after cooking to an internal temperature of 71 °C on an open-hearth grill set at 210 °C, a 1 cm by 5 cm core is cut from the steak, parallel to muscle fibre direction, using 2 knife blades set 1 cm apart. This warm core is then subjected to the Slice Shear Force protocol (SSF) to evaluate meat texture. The use of the variable angle cutting box and the SSF protocol provides an accurate representation of the maximal shear force, as the slice and muscle fibres are consistently parallel. Therefore, the variable angle cutting box, in conjunction with the SSF protocol, can be used as a high-throughput technique to accurately evaluate meat tenderness in different locations of the longissimus muscle and, potentially, in other muscles. PMID:23644653

  3. Tests of Two Full-Scale Propellers with Different Pitch Distributions, at Blade Angles up to 60 Degrees

    NASA Technical Reports Server (NTRS)

    Biermann, David; HARTMAN EDWIN P

    1939-01-01

    Two 3-blade 10-foot propellers were operated in front of a liquid-cooled engine nacelle. The propellers differed only in pitch distribution; one had normal distribution (nearly constant pitch for a blade angle of 15 degrees at 0.75 radius), and the other had the pitch of the tip sections decreased with respect to that for the shank sections (blade angle of 35 degrees for nearly constant pitch distribution). Propeller blade angles at 0.75r from 15 degrees to sixty degrees, corresponding to design speeds up to 500 miles per hour, were investigated. Propeller blade angles at 0.75r from 15 degrees to 60 degrees, corresponding to design speeds up to 500 miles per hour, were investigated. The results indicated that the propulsive efficiency at a blade angle of 60 degrees was about 9 percent less than the maximum value of 86 percent, which occurred at blade angle of about 30 degrees. The efficiency at a blade angle of 60 degrees was increased about 7 percent by correcting for the effect of a spinner and, at a blade angle of 30 degrees about 3 percent. The peak efficiencies for the propeller having the washed-out pitch distribution were slightly less than for the normal propeller but the take-off efficiency was generally higher.

  4. An experimental study of the sensitivity of helicopter rotor blade tracking to root pitch adjustment in hover

    NASA Technical Reports Server (NTRS)

    Wilkie, W. Keats; Langston, Chester W.; Mirick, Paul H.; Singleton, Jeffrey D.; Wilbur, Matthew L.; Yeager, William T., Jr.

    1991-01-01

    The sensitivity of blade tracking in hover to variations in root pitch was examined for two rotor configurations. Tests were conducted using a four bladed articulated rotor mounted on the NASA-Army aeroelastic rotor experimental system (ARES). Two rotor configurations were tested: one consisting of a blade set with flexible fiberglass spars and one with stiffer (by a factor of five in flapwise and torsional stiffnesses) aluminum spars. Both blade sets were identical in planform and airfoil distribution and were untwisted. The two configurations were ballasted to the same Lock number so that a direct comparison of the tracking sensitivity to a gross change in blade stiffness could be made. Experimental results show no large differences between the two sets of blades in the sensitivity of the blade tracking to root pitch adjustments. However, a measurable reduction in intrack coning of the fiberglass spar blades with respect to the aluminum blades is noted at higher rotor thrust conditions.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  6. Differential interferometry with adjustable spatial carrier fringes for turbine blade cascade flow investigations

    NASA Astrophysics Data System (ADS)

    Woisetschläger, J.; Pretzler, G.; Jericha, H.; Mayrhofer, N.; Pirker, H. P.

    Digital evaluated differential interferometry using adjustable spatial carrier fringes was applied to flow measurements in a transonic turbine blade cascade. The interferograms were evaluated using a two-dimensional Fourier Analysis. This evaluation provided density gradient maps of the flow field in a digital form. A specially designed interferometer was used allowing adjustment of sensitivity and superposition of carrier-fringe system separately. This type of interferometer is also highly insensitive to vibration noise. For a turbine blade cooling film a comparison of this type of differential interferometry with holographic interferometry and a Schlieren visualisation is also given. As a result differential interferometry using adjustable spatial carrier fringes and digital fringe analysis gave density-gradient maps similar to Schlieren recordings but of quantitative nature, thus enabling compensation of wave front distortions. Integration of these density gradient maps resulted in density maps which were then compared to recordings done with pulsed holographic interferometry.

  7. Aerodynamic damping of blade flap motions at high angles of attack

    SciTech Connect

    Hansen, A.C.

    1995-09-01

    The YawDyn computer code is used to calculate the aerodynamic damping for a typical teetering rotor configuration. The code has been modified to calculate the net work done by aerodynamic forces in one complete rotor revolution. All cases were run for a teetering rotor similar to the ESI-80 with a specified teeter angle motion in order to isolate the aerodynamic effects from the inertial and gravitational loads. Effects of nonlinear static stall, dynamic stall, dynamic inflow, and delayed static stall due to rotation stability of flap motions in high winds. Contributions of the various steady and unsteady aerodynamic effects are presented for two airfoils: the LS(1) and the NREL Thin Airfoil Family (S805A, S806, S807). Teeter stability is compared for a blade with 10{degree} of linear twist and a blade with optimum aerodynamic twist.

  8. Investigation about Rotor-stator Interaction with an Adjustable Leaned Vane Blade

    NASA Astrophysics Data System (ADS)

    Wu, Yadong; Tian, Jie; Ouyang, Hua; Du, Zhaohui; Liu, Haijian

    2014-12-01

    This paper focuses on the noise reduction benefits of stator lean effect for rotor-stator interaction. The compressor with 3 blade lean angle of downstream stator was investigated by experimental and numerical study. The noise spectra of the acoustic measurement were obtained by the outside noise test. And the tone noise was extracted from the total noise sound pressure level (SPL). The unsteady loading of the stators' blade surface were also obtained. The pressure fluctuation amplitude was extracted from the numerical study, and the phase distribution of the wake presented the detail distribution of the wake phase. The numerical study shows that lean positive has less unsteady loading than negative, and lean positive case has the maximum phase lag.

  9. Effect of Various Blade Modifications on Performance of a 16-Stage Axial-Flow Compressor. III - Effect on Over-All Performance Characteristics on Increasing Stator-Blade Angles in Inlet Stages

    NASA Technical Reports Server (NTRS)

    Medeiros, Arthur A.; Hatch, James E.

    1952-01-01

    The stator-blade angles in the first four stages of a 16-stage axial-flow compressor were increased in order to decrease the angles of attack of these stages, and thereby to improve part-speed performance. The performance of this modified compressor was compared with that of the same compressor with original blade angles.

  10. Effect of Various Blade Modifications on Performance of a 16-Stage Axial-Flow Compressor. II - Effect on Over-All Performance Characteristics of Increasing Twelfth through Fifteenth Stage Stator-Blade Angles 3 deg

    NASA Technical Reports Server (NTRS)

    Hatch, James E.; Medeiros, Arthur A.

    1952-01-01

    The stator-blade angles in the twelfth through fifteenth stages of a 16-stage axial-flow compressor were increased 3O. The over-all performance of this modified compressor is compared to the performance of the compressor with original blade angles. The matching characteristics of the modified compressor and a two-stage turbine were obtained and compared to those of the compressor with original blade angles and the same turbine.

  11. Adjustable-Viewing-Angle Endoscopic Tool for Skull Base and Brain Surgery

    NASA Technical Reports Server (NTRS)

    Bae, Youngsam; Liao, Anna; Manohara, Harish; Shahinian, Hrayr

    2008-01-01

    that of an endo-scissor, but the linkage would be configured to enable adjustment of the camera angle instead of actuation of a scissor blade. It is envisioned that thicknesses of the tool shaft and the camera would be less than 4 mm, so that the camera-tipped tool could be swiftly inserted and withdrawn through a dime-size opening. Electronic cameras having dimensions of the order of millimeters are already commercially available, but their designs are not optimized for use in endoscopic brain surgery. The variety of potential endoscopic, thoracoscopic, and laparoscopic applications can be expected to increase as further development of electronic cameras yields further miniaturization and improvements in imaging performance.

  12. An evaluation of several methods of determining the local angle of attack on wind turbine blades

    NASA Astrophysics Data System (ADS)

    Guntur, S.; Sørensen, N. N.

    2014-12-01

    Several methods of determining the angles of attack (AOAs) on wind turbine blades are discussed in this paper. A brief survey of the methods that have been used in the past are presented, and the advantages of each method are discussed relative to their application in the BEM theory. Data from existing as well as new full rotor CFD computations of the MEXICO rotor are used in this analysis. A more accurate estimation of the AOA is possible from 3D full rotor CFD computations, but when working with experimental data, pressure measurements and sectional forces are often the only data available. The aim of this work is to analyse the reliability of some of the simpler methods of estimating the 3D effective AOA compared some of the more rigorous CFD based methods.

  13. Axial-flow compressor turning angle and loss by inviscid-viscous interaction blade-to-blade computation

    NASA Technical Reports Server (NTRS)

    Hansen, E. C.; Serovy, G. K.; Sockol, P. M.

    1979-01-01

    A method for computation of the flow field around an arbitrary airfoil cascade on an axially symmetric blade-to-blade surface was developed which takes into account the development and separation of the blade surface boundary layers and mixing in the wake. The method predicts the overall fluid turning and total pressure loss in the context of an inviscid-viscous interaction scheme. The inviscid flow solution is obtained from a compressible flow matrix method. The viscous flow is obtained from a differential boundary layer method which calculates laminar, transitional and turbulent boundary layers. Provisions for the calculation of laminar and turbulent separation regions were added to the viscous scheme. The combined inviscid-viscous interaction scheme described yields results which are quantitatively consistent with experimental data. This suggests that the physical basis for the interactive system is correct and justifies continued exploration and use of the method.

  14. Method for estimating the aerodynamic coefficients of wind turbine blades at high angles of attack

    NASA Astrophysics Data System (ADS)

    Beans, E. W.; Jakubowski, G. S.

    1983-12-01

    The method is based on the hypothesis that at high angles of attack the force on an airfoil is produced by the deflection of the fluid across the lower surface. It is also hypothesized that all airfoils behave the same regardless of shape and that the effects of circulation and skin friction are small. It is pointed out that the expression for the force N normal to the airfoil due to momentum exchange can be written in terms of the component parallel to the flow (drag) and the component perpendicular to the flow (lift). A comparison of estimated values with measured values and generally accepted data indicates that the method given here estimates coefficients which are low. It is thought that the difference may derive from the persistence of circulation at high angles of attack. Low estimates are not seen as a serious limitation to the designer of wind turbines. Owing to the fifth power diameter relation, the effect of a low estimate of performance on the inner portion of the blade is minimized.

  15. Effects of rising angle on upstream blades and intermediate turbine duct

    NASA Astrophysics Data System (ADS)

    Liu, Jun; Wang, Pei; Du, Qiang; Liu, Guang; Zhu, Junqiang

    2016-08-01

    With the improvement of requirement, design and manufacture technology, aero-engines for the future are characterized by further reduction in fuel consumption, cost, but increment in propulsion efficiency, which leads to ultra-high bypass ratio. The intermediate turbine duct (ITD), which connects the high pressure turbine (HPT) with the low pressure turbine (LPT), has a critical impact on the overall performances of such future engines. Therefore, it becomes more and more urgent to master the design technique of aggressive, even super-aggressive ITDs. Over the last years, a lot of research works about the flow mechanism in the diffuser ducts were carried out. Many achievements were reported, but further investigation should be performed. With the aid of numerical method, this paper focuses on the change of performance and flow field of ITD, as well as nearby turbines, brought by rising angle (RA). Eight ITDs with the same area ratio and length, but different RAs ranges from 8 degrees to 45 degrees, are compared. According to the investigation, flow field, especially outlet Ma of swirl blade is influenced by RA under potential effect, which is advisable for designers to modify HPT rotor blades after changing ITD. In addition to that, low velocity area moves towards upstream until the first bend as RA increases, while pressure loss distribution at S2 stream surface shows that hub boundary layer is more sensitive to RA, and casing layer keeps almost constant. On the other hand, the overall total pressure loss could keep nearly equivalent among different RA cases, which implies the importance of optimization.

  16. Controlled pitch-adjustment of impeller blades for an intravascular blood pump.

    PubMed

    Throckmorton, Amy L; Sciolino, Michael G; Downs, Emily A; Saxman, Robert S; López-Isaza, Sergio; Moskowitz, William B

    2012-01-01

    Thousands of mechanical blood pumps are currently providing circulatory support, and the incidence of their use continues to increase each year. As the use of blood pumps becomes more pervasive in the treatment of those patients with congestive heart failure, critical advances in design features to address known limitations and the integration of novel technologies become more imperative. To advance the current state-of-the-art in blood pump design, this study investigates the inclusion of pitch-adjusting blade features in intravascular blood pumps as a means to increase energy transfer; an approach not explored to date. A flexible impeller prototype was constructed with a configuration to allow for a variable range of twisted blade geometries of 60-250°. Hydraulic experiments using a blood analog fluid were conducted to characterize the pressure-flow performance for each of these twisted positions. The flexible, twisted impeller was able to produce 1-25 mmHg for 0.5-4 L/min at rotational speeds of 5,000-8,000 RPM. For a given twisted position, the pressure rise was found to decrease as a function of increasing flow rate, as expected. Generally, a steady increase in the pressure rise was observed as a function of higher twisted degrees for a constant rotational speed. Higher rotational speeds for a specific twisted impeller configuration resulted in a more substantial pressure generation. The findings of this study support the continued exploration of this unique design approach in the development of intravascular blood pumps. PMID:22691415

  17. Effect of Various Blade Modifications on Performance of a 16-Stage High-pressure-ratio Axial-flow Compressor.Angles 3 deg. 1; Effect on Over-all Performance Characteristics of Decreasing Twelfth Through Fifteenth State Stator-blade Angles 3 deg

    NASA Technical Reports Server (NTRS)

    Medeiros, Arthur A.; Hatch, James E.; Dugan, James F., Jr.

    1952-01-01

    The stator-blade angles in the twelfth to fifteenth stages of a 16-stage high-pressure-ratio axial-flow compressor were decreased 3 deg The over-all performance of this compressor is compared with the performance of the same compressor with standard blade angles. The matching characteristics of the modified compressor and a two-stage turbine were also obtained and compared with those of the compressor with the original blade angles and the same turbine.

  18. Turbofan blade stresses induced by the flow distortion of a VTOL inlet at high angles of attack

    NASA Technical Reports Server (NTRS)

    Williams, R. C.; Diedrich, J. H.; Shaw, R. J.

    1983-01-01

    A 51-cm-diameter turbofan with a tilt-nacelle VTOL inlet was tested in the Lewis Research Center's 9- by 15-Ft Low Speed Wind Tunnel at velocities up to 72 m/s and angles of attack up to 120 deg. Fan-blade vibratory stress levels were investigated over a full aircraft operating range. These stresses were due to inlet air flow distortion resulting from (1) internal flow separation in the inlet, and (2) ingestion of the exterior nacelle wake. Stress levels are presented, along with an estimated safe operating envelope, based on infinite blade fatigue life.

  19. Method of Estimating the Incompressible-flow Pressure Distribution of Compressor Blade Sections at Design Angle of Attack

    NASA Technical Reports Server (NTRS)

    Erwin, John R; Yacobi, Laura A

    1953-01-01

    A method was devised for estimating the incompressible-flow pressure distribution over compressor blade sections at design angle of attack. The theoretical incremental velocities due to camber and thickness of the section as an isolated airfoil are assumed proportional to the average passage velocity and are modified by empirically determined interference factors. Comparisons were made between estimated and test pressure distributions of NACA 65-series sections for typical conditions. Good agreement was obtained.

  20. Contact angle adjustment in equation-of-state-based pseudopotential model

    NASA Astrophysics Data System (ADS)

    Hu, Anjie; Li, Longjian; Uddin, Rizwan; Liu, Dong

    2016-05-01

    The single component pseudopotential lattice Boltzmann model has been widely applied in multiphase simulation due to its simplicity and stability. In many studies, it has been claimed that this model can be stable for density ratios larger than 1000. However, the application of the model is still limited to small density ratios when the contact angle is considered. The reason is that the original contact angle adjustment method influences the stability of the model. Moreover, simulation results in the present work show that, by applying the original contact angle adjustment method, the density distribution near the wall is artificially changed, and the contact angle is dependent on the surface tension. Hence, it is very inconvenient to apply this method with a fixed contact angle, and the accuracy of the model cannot be guaranteed. To solve these problems, a contact angle adjustment method based on the geometry analysis is proposed and numerically compared with the original method. Simulation results show that, with our contact angle adjustment method, the stability of the model is highly improved when the density ratio is relatively large, and it is independent of the surface tension.

  1. The effect of blade outlet angle on performance and internal flow condition of mini turbo-pump

    NASA Astrophysics Data System (ADS)

    Shigemitsu, T.; Fukutomi, J.; Nasada, R.; Kaji, K.

    2011-03-01

    Mini turbo-pumps having a diameter smaller than 100mm are employed in many fields; automobile radiator pump, ventricular assist pump, cooling pump for electric devices, washing machine pump and so on. Further, the needs for mini turbo-pumps would become larger with the increase of the application of it for electrical machines. It is desirable that the mini turbo-pump design is as simple as possible due to restriction to make precise manufactures. But the design method for the mini turbo-pump is not established because the internal flow condition for these small-sized fluid machineries is not clarified and conventional theory is not conductive for small-sized pumps. Three types of rotors with different outlet angles are prepared for an experiment and a numerical analysis. The performance tests are conducted with these rotors in order to investigate the effect of the blade outlet angle on performance and internal flow condition of mini turbo-pumps. It is clarified from the experimental results that head of the mini turbo-pump increases and maximum efficiency flow rate shifts to larger flow rate according to the increase of the blade outlet angle, however the maximum efficiency decreases with the increase of it. In the present paper, the performance of the mini turbo-pump is shown and the internal flow conditions are clarified with the results of the experiment and the numerical flow analysis. Furthermore, the effects of the blade outlet angle on the performance are investigated and high performance design with simple structure for the mini turbo-pump would be considered.

  2. Experimental investigation of an axial-flow-compressor inlet stage operating at transonic relative inlet Mach numbers V : rotor blade-element performance at a reduced blade angle

    NASA Technical Reports Server (NTRS)

    Schwenk, Francis C; Lewis, George W , Jr; Lieblein, Seymour

    1957-01-01

    At a corrected speed of 1100 feet per second, the low-blade-angle rotor operated with a relative inlet Mach number of 1.2, a diffusion factor of 0.65, and an axial velocity ratio of 0.71 in the tip region (11 percent of passage height away from the outer wall). The measured minimum-loss coefficient was 0.35, and this value falls above a previous correlation of rotor losses with diffusion factor. Through a comparison with data for three other rotors, the occurrence of high losses was related to a high suction-surface Mach number. These comparisons also indicated that axial velocity ratios between 0.73 and 1.10 have no independent effect on losses.

  3. Liquid crystal pretilt angle control using adjustable wetting properties of alignment layers

    SciTech Connect

    Ahn, Han Jin; Kim, Jong Bok; Kim, Kyung Chan; Hwang, Byoung Har; Kim, Jong Tae; Baik, Hong Koo; Park, Jin Seol; Kang, Daeseung

    2007-06-18

    The authors demonstrate the production of amorphous fluorinated carbon (a-C:F) thin film with adjustable wetting properties, inducing variable liquid crystal (LC) pretilt angles. To control the surface wetting properties, they apply a dual radio frequency magnetron system with a controlled power ratio of targets. In this manner we obtain various compositional surfaces with fluorine and carbon components and adjust the surface energy with regard to the various compositions. Whereas the fluorine-rich a-C:F layer shows a preference for homeotropic (vertical) LC alignment, the carbon-rich a-C:F layer shows a planar LC alignment. To achieve uniform LC alignment with a proper pretilt angle, an accelerated Ar{sup +} ion beam irradiates the films after the deposition process. The ion beam selectively destroys the surface bonding of the a-C:F films, yielding an intermediate pretilt angle.

  4. Blade for turbine engine

    NASA Technical Reports Server (NTRS)

    Suciu, Gabriel L. (Inventor); Babu, Michael (Inventor); Murdock, James R. (Inventor)

    2004-01-01

    A blade for a turbine engine having a centerline. The blade comprises: a root section extending at an angle relative to the centerline; and an airfoil section extending from the root section. The root section is directly adjacent said airfoil section. In other words, the blade is neckless. The blade is part of a rotor assembly, and is preferably a fan blade.

  5. Performance of Single-Stage Turbine of Mark 25 Torpedo Power Plant with Two Special Nozzles. II; Efficiency with 20 Degrees-Inlet-Angle Rotor Blades

    NASA Technical Reports Server (NTRS)

    Schum, Harold J.; Whitney, Warren J.

    1949-01-01

    A single-stage modification of the turbine from a Mark 25 torpedo power plant was investigated to determine the performance with two nozzle designs in combination with special rotor blades having a 20 inlet angle. The performance is presented in terms of blade, rotor, and brake efficiency as a function of blade-jet speed ratio for pressure ratios of 8, 15 (design), and 20. The blade efficiency with the nozzle having circular pas- sages (K) was equal to or higher than that with the nozzle having rectangular passages (J) for all pressure ratios and speeds investigated. The maximum blade efficiency of 0.571 was obtained with nozzle K at a pressure ratio of 8 and a blade-jet speed ratio of 0.296. The difference in blade efficiency was negligible at a pressure ratio of 8 at the low speeds; the maxim difference was 0.040 at a pressure ratio of 20 and a blade-jet speed ratio of 0.260.

  6. Analytical investigation of turbines with adjustable stator blades and effect of these turbines on jet-engine performance

    NASA Technical Reports Server (NTRS)

    Silvern, David H; Slivka, William R

    1950-01-01

    Adjustable-stator turbines are applied to turbojet engines and probable performance is compared with conventional engines with and without variable-area exhaust nozzles. Variation in stator-exit angle and exhaust area was not excessive for wide ranges of engine output. Variation in turbine efficiency for contemporary turbines equipped with adjustable stators was small. Improvements from 4.5 to 17 percent in over-all engine specific fuel consumption over conventional engines and from 2 to 8.5 percent over engines equipped with only adjustable-area exhaust nozzles were obtained at 60-percent rated power with adjustable-stator turbines and variable-area exhaust nozzles. The improvements depend on design parameters.

  7. The measurement of boundary layers on a compressor blade in cascade at high positive incidence angle. 2: Data report

    NASA Technical Reports Server (NTRS)

    Deutsch, S.; Zierke, W. C.

    1986-01-01

    Boundary layer and near-wake velocity measurements have been made in the well documented flow field about a double circular arc compressor blade in cascade, at an incidence angle of 5 deg. and a chord Reynolds number of 500,000. In Part 2 of this report these measurements were analyzed and presented in standard graphical format. The flow geometry, measurement techniques, and physics of the flow field were also discussed. In this, part 2 of the report, raw and analyzed data are presented in tabulated form in an attempt to make this data more accessible to computational comparison. Also included in part 2 is a description of the data analysis employed. A computer tape containing the data is available.

  8. On the magic-angle turning and phase-adjusted spinning sidebands experiments.

    PubMed

    Hung, Ivan; Gan, Zhehong

    2010-05-01

    The underlying relation between the magic-angle turning (MAT) and phase-adjusted spinning sidebands (PASS) experiments is examined. The MAT experiment satisfies the PASS conditions for separating spinning sidebands with a non-constant total evolution time and only requires linear t(1) increments of up to one rotor period. The time-domain data of the two experiments are related by a shearing transformation. A combination of the linear evolution-time increments of MAT and simple data processing of PASS are particularly attractive for the implementation of MAT for measuring chemical shift anisotropy. PMID:20202873

  9. Dynamic Collimator Angle Adjustments During Volumetric Modulated Arc Therapy to Account for Prostate Rotations

    SciTech Connect

    Boer, Johan de; Wolf, Anne Lisa; Szeto, Yenny Z.; Herk, Marcel van; Sonke, Jan-Jakob

    2015-04-01

    Purpose: Rotations of the prostate gland induce considerable geometric uncertainties in prostate cancer radiation therapy. Collimator and gantry angle adjustments can correct these rotations in intensity modulated radiation therapy. Modern volumetric modulated arc therapy (VMAT) treatments, however, include a wide range of beam orientations that differ in modulation, and corrections require dynamic collimator rotations. The aim of this study was to implement a rotation correction strategy for VMAT dose delivery and validate it for left-right prostate rotations. Methods and Materials: Clinical VMAT treatment plans of 5 prostate cancer patients were used. Simulated left-right prostate rotations between +15° and −15° were corrected by collimator rotations. We compared corrected and uncorrected plans by dose volume histograms, minimum dose (D{sub min}) to the prostate, bladder surface receiving ≥78 Gy (S78) and rectum equivalent uniform dose (EUD; n=0.13). Each corrected plan was delivered to a phantom, and its deliverability was evaluated by γ-evaluation between planned and delivered dose, which was reconstructed from portal images acquired during delivery. Results: On average, clinical target volume minimum dose (D{sub min}) decreased up to 10% without corrections. Negative left-right rotations were corrected almost perfectly, whereas D{sub min} remained within 4% for positive rotations. Bladder S78 and rectum EUD of the corrected plans matched those of the original plans. The average pass rate for the corrected plans delivered to the phantom was 98.9% at 3% per 3 mm gamma criteria. The measured dose in the planning target volume approximated the original dose, rotated around the simulated left-right angle, well. Conclusions: It is feasible to dynamically adjust the collimator angle during VMAT treatment delivery to correct for prostate rotations. This technique can safely correct for left-right prostate rotations up to 15°.

  10. Bundle block adjustment of airborne three-line array imagery based on rotation angles.

    PubMed

    Zhang, Yongjun; Zheng, Maoteng; Huang, Xu; Xiong, Jinxin

    2014-01-01

    In the midst of the rapid developments in electronic instruments and remote sensing technologies, airborne three-line array sensors and their applications are being widely promoted and plentiful research related to data processing and high precision geo-referencing technologies is under way. The exterior orientation parameters (EOPs), which are measured by the integrated positioning and orientation system (POS) of airborne three-line sensors, however, have inevitable systematic errors, so the level of precision of direct geo-referencing is not sufficiently accurate for surveying and mapping applications. Consequently, a few ground control points are necessary to refine the exterior orientation parameters, and this paper will discuss bundle block adjustment models based on the systematic error compensation and the orientation image, considering the principle of an image sensor and the characteristics of the integrated POS. Unlike the models available in the literature, which mainly use a quaternion to represent the rotation matrix of exterior orientation, three rotation angles are directly used in order to effectively model and eliminate the systematic errors of the POS observations. Very good experimental results have been achieved with several real datasets that verify the correctness and effectiveness of the proposed adjustment models. PMID:24811075

  11. Effect of Various Blade Modifications in Performance of a 16-Stage Axial-flow Compressor. IV - Effect on Over-all Performance Characteristics of Decreasing Twelfth through Fifteenth Stage Stator-blade Angles 3 deg and Increasing Stator Angles in the Inlet Stages

    NASA Technical Reports Server (NTRS)

    Hatch, James E.; Medeiros, Arthur A.

    1952-01-01

    The performance of a 16-stage axial-flow compressor, in which two modifications of unloaded inlet stages were combined with loaded exit stages, has been determined. In the first modification the exit stages were loaded by decreasing the twelfth through fifteenth stage stator angles 3 deg. as compared with the blade angles in the original compressor, and the inlet stages were unloaded by increasing the blade angles the following amounts: guide vanes and first-stage stator, 6 deg; second- and third-stage stators, 4 deg.; and fourth-stage stators, 3 deg. The over-all performance of this configuration was compared with that of the compressor with the original blade angles. The peak efficiency was increased at all speeds below design and the weight flow was higher at speeds below 80 percent of design, the same at 80 percent of design, and lower at speeds abovce 80 percent of design. The maximum reduction in weight flow occurred at design speed. The surge limit line was higher at speeds between 75 and 90 percent of design when presented on a pressure ratio against weight flow basis. The second configuration was the same as the first with the exception that the second-, third-, and fourth-stage stator blade angles were the same as in the compressor with the original blade angles. A comparison of the performance of this configuration with that of the compressor with the original blade angles showed the same general trends of changes in performance as the first configuration. Comparisons were made of compressor configurations to show the effects upon the performance of decreased loading in the inlet stages. Below 75 percent of design speed, decreased loading results in increased weight flow and peak efficiency; above 80 percent of design speed, decreased loading in the inlet stages results in decreased weight flow and small changes in peak efficiencies. Between 75 and 90 percent of design the changes in surge weight flow and pressure ratio were such that the surge limit

  12. BLADED IMPELLER FOR TURBOBLOWERS

    DOEpatents

    Baumann, K.

    1949-10-01

    A means is given of holding open-sided impeller blades in a turbo-rotor. Two half blades, with dovetail roots of sufficient weight to contain the center of gravity, are fitted into slots cut in the rotor so as to form the desired angle between the blade faces. The adjoining edges of the half blades are welded to form one solid blade that is securely locked an the rotor. This design permits the manufacture of a V shaped impeller blade without the need of machining the entire V shaped contour from a single blank, and furthermore provides excellent locking characteristics for attachment to the rotor.

  13. Orientating layers with adjustable pretilt angles for liquid crystals deposited by a linear atmospheric pressure plasma source

    SciTech Connect

    Jian, Shih-Jie; Kou, Chwung-Shan; Hwang, Jennchang; Lee, Chein-Dhau; Lin, Wei-Cheng

    2013-06-15

    A method for controlling the pretilt angles of liquid crystals (LC) was developed. Hexamethyldisiloxane polymer films were first deposited on indium tin oxide coated glass plates using a linear atmospheric pressure plasma source. The films were subsequently treated with the rubbing method for LC alignment. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy measurements were used to characterize the film composition, which could be varied to control the surface energy by adjusting the monomer feed rate and input power. The results of LC alignment experiments showed that the pretilt angle continuously increased from 0 Degree-Sign to 90 Degree-Sign with decreasing film surface energy.

  14. Effects of pelvic adjustment on pelvic posture and angles of the lower limb joints during walking in female university students

    PubMed Central

    Cho, Misuk

    2016-01-01

    [Purpose] This study investigated the effects of pelvic adjustment on pelvic posture and lower limb joint angles during walking in female university students. [Subjects] Thirty healthy female university students were randomly assigned to an experimental group (pelvic adjustment group, n = 15) and a control group (stretching group, n = 15). [Methods] Pelvic adjustment was performed three times on the experimental group. The control group performed three sets of pelvic muscle stretching for 15 minutes. A back mapper and motion analysis equipment were used to measure pelvic posture and angles of lower limb joints for the experimental and control group. [Results] The values obtained before and after the intervention were compared. For the experimental group, the results were significantly different in terms of reduced differences in hip flexion between the left and right hips and in knee abduction between the left and right knees. Differences in pelvic position and pelvic torsion were also found in the experimental group. No significant differences in the control group were identified. [Conclusion] Pelvic adjustment affects pelvic position and torsion and this enhancement to pelvic stability decreases hip flexion and knee abduction during walking. PMID:27190468

  15. Reliability of cut mark analysis in human costal cartilage: the effects of blade penetration angle and intra- and inter-individual differences.

    PubMed

    Puentes, K; Cardoso, H F V

    2013-09-10

    Identification of tool class characteristics from cut marks in either bone or cartilage is a valuable source of data for the forensic scientist. Various animal models have been used in experimental studies for the analysis of individual and class characteristics. However, human tissue has seldom been used and it is likely to differ from that of non-humans in key aspects. This study wishes to assess how the knife's blade angle, and both intra- and inter-individual variation in cartilage samples affect the ability of costal cartilage to retain the original class characteristics of the knife, as measured microscopically by the distance between consecutive striations. The 120 cartilaginous samples used in this study originated from the ribcage of 6 male cadavers which were submitted to autopsy at the North Branch of the National Institute of Legal Medicine, in Portugal. Three different serrated knives were purchased from a large department store, and were used in the experimental cuts. Samples of costal cartilage from 2 individuals were assigned to each knife. Each individual provided 20 cartilage samples. Cartilage samples were manually cut using each of the three knives, following two motions: one straight up-and-down cutting motion and parallel and one perpendicular to the blade's teeth long axis forward cutting motion. Casts of the samples were made with Mikrosil(®). Image capture and processing were performed with an Olympus stereomicroscope and its software. The blade's penetration angle and inter-individual variation were shown to affect the identification of the tool class characteristics from the striation pattern observed in a kerf wall, although this seems to be related only to the degree of calcification of the costal cartilage. Intra-individual variation does not seem to significantly affect the identification of the tool class characteristics from the striation pattern observed in a kerf wall, for the same knife following the same motion. Although this

  16. Effect of blade wrap angle on efficiency and noise of small radial fan impellers—A computational and experimental study

    NASA Astrophysics Data System (ADS)

    Scheit, C.; Karic, B.; Becker, S.

    2012-02-01

    Radial impellers have several technical applications. Regarding their aerodynamic performance, they are well optimized nowadays, but this is in general not true regarding acoustics. This work was therefore concerned with analyzing the flow structures inside isolated radial impellers together with the far-field sound radiated from them in order to optimize the aerodynamic and acoustic performance. Both numerical and experimental techniques were applied in order to study the effect of varying wrap angle and otherwise identical geometric configuration on aerodynamics and acoustics of the radial impellers. The results give a detailed insight into the processes leading to sound generation in radial impellers. Measurements were performed using laser Doppler anemometry for the flow field and microphone measurements to analyze the radiated noise. In addition, unsteady aerodynamic simulations were carried out to calculate the compressible flow field. An acoustic analogy was employed to compute far-field noise. Finally, the phenomena responsible for tonal noise and the role of the wrap angle could be identified. Using this knowledge, design guidelines are given to optimize the impeller with respect to the radiated noise. This work shows that improved aerodynamic efficiency for isolated impellers does not automatically lead to a smaller flow-induced sound radiation.

  17. On the inverse problem of blade design for centrifugal pumps and fans

    NASA Astrophysics Data System (ADS)

    Kruyt, N. P.; Westra, R. W.

    2014-06-01

    The inverse problem of blade design for centrifugal pumps and fans has been studied. The solution to this problem provides the geometry of rotor blades that realize specified performance characteristics, together with the corresponding flow field. Here a three-dimensional solution method is described in which the so-called meridional geometry is fixed and the distribution of the azimuthal angle at the three-dimensional blade surface is determined for blades of infinitesimal thickness. The developed formulation is based on potential-flow theory. Besides the blade impermeability condition at the pressure and suction side of the blades, an additional boundary condition at the blade surface is required in order to fix the unknown blade geometry. For this purpose the mean-swirl distribution is employed. The iterative numerical method is based on a three-dimensional finite element method approach in which the flow equations are solved on the domain determined by the latest estimate of the blade geometry, with the mean-swirl distribution boundary condition at the blade surface being enforced. The blade impermeability boundary condition is then used to find an improved estimate of the blade geometry. The robustness of the method is increased by specific techniques, such as spanwise-coupled solution of the discretized impermeability condition and the use of under-relaxation in adjusting the estimates of the blade geometry. Various examples are shown that demonstrate the effectiveness and robustness of the method in finding a solution for the blade geometry of different types of centrifugal pumps and fans. The influence of the employed mean-swirl distribution on the performance characteristics is also investigated.

  18. Articulated limiter blade for a tokamak fusion reactor

    DOEpatents

    Doll, David W.

    1985-01-01

    A limiter blade for a large tokomak fusion reactor includes three articulated blade sections for enabling the limiter blade to be adjusted for plasmas of different sizes. Each blade section is formed of a rigid backing plate carrying graphite tiles coated with titanium carbide, and the limiter blade forms a generally elliptic contour in both the poloidal and toroidal directions to uniformly distribute the heat flow to the blade. The limiter blade includes a central blade section movable along the major radius of the vacuum vessel, and upper and lower pivotal blade sections which may be pivoted by linear actuators having rollers held to the back surface of the pivotal blade sections.

  19. Articulated limiter blade for a tokamak fusion reactor

    DOEpatents

    Doll, D.W.

    1982-10-21

    A limiter blade for a large tokomak fusion reactor includes three articulated blade sections for enabling the limiter blade to be adjusted for plasmas of different sizes. Each blade section is formed of a rigid backing plate carrying graphite tiles coated with titanium carbide, and the limiter blade forms a generally elliptic contour in both the poloidal and toroidal directions to uniformly distribute the heat flow to the blade. The limiter blade includes a central blade section movable along the major radius of the vacuum vessel, and upper and lower pivotal blade sections which may be pivoted by linear actuators having rollers held to the back surface of the pivotal blade sections.

  20. Effect of Helicopter Blade Dynamics on Blade Aerodynamic and Structural Loads

    NASA Technical Reports Server (NTRS)

    Heffernan, Ruth M.

    1987-01-01

    The effect of rotor blade dynamics on aerodynamic and structural loads is examined for a conventional, main- rotor helicopter using both a comprehensive rotorcraft analysis (CAMRAD) and night test data. The impact of blade dynamics on blade section lift-coefficient time histories is studied by comparing predictions from both a rigid blade analysis and an elastic blade analysis with helicopter flight test data. The elastic blade analysis better predicts high-frequency behavior of section lift. In addition, components of the blade angle of attack, such as elastic blade twist, blade nap rate, blade slope velocity, and inflow, are examined as a function of blade mode. Elastic blade motion affects the blade angle of attack by a few tenths of a degree, and up to the sixth rotor harmonic. A similar study of the influence of blade dynamics on bending and torsion moments was also conducted. The modal analysis of the predicted blade structural loads suggested that five elastic bending deg of freedom (four flap and one lag) and three elastic torsion deg of freedom contributed to calculations of the blade structural loads. However, when structural bending load predictions from several elastic blade analyses were compared with flight test data, an elastic blade model consisting of only three elastic bending modes (first and second flap, and first lag), and two elastic torsion modes was found to be sufficient for maximum correlation.

  1. Transonic turbine blade cascade testing facility

    NASA Technical Reports Server (NTRS)

    Verhoff, Vincent G.; Camperchioli, William P.; Lopez, Isaac

    1992-01-01

    NASA LeRC has designed and constructed a new state-of-the-art test facility. This facility, the Transonic Turbine Blade Cascade, is used to evaluate the aerodynamics and heat transfer characteristics of blade geometries for future turbine applications. The facility's capabilities make it unique: no other facility of its kind can combine the high degree of airflow turning, infinitely adjustable incidence angle, and high transonic flow rates. The facility air supply and exhaust pressures are controllable to 16.5 psia and 2 psia, respectively. The inlet air temperatures are at ambient conditions. The facility is equipped with a programmable logic controller with a capacity of 128 input/output channels. The data acquisition system is capable of scanning up to 1750 channels per sec. This paper discusses in detail the capabilities of the facility, overall facility design, instrumentation used in the facility, and the data acquisition system. Actual research data is not discussed.

  2. Further development of the swinging-blade Savonius rotor

    NASA Astrophysics Data System (ADS)

    Aldoss, T. K.; Najjar, Y. S. H.

    Savonius rotor performance is improved by allowing both downwind and upwind rotor blades to swing back through an optimum angle. This will minimize the drag on the upwind blade and maximize the drag on the down-wind blade. A combination of 50 degrees upwind blade swing angle and 13.5 degrees downwind blade swing angle have been found experimentally to be the optimum swing angles that increased the rotor maximum power coefficient to about 23.5 percent compared with 18 percent with optimum upwind blade swing alone.

  3. Effect of helicopter blade dynamics on blade aerodynamic and structural loads

    NASA Technical Reports Server (NTRS)

    Heffernan, Ruth M.

    1987-01-01

    The effect of rotor blade dynamics on aerodynamic and structural loads is examined for a conventional, main-rotor helicopter using a comprehensive rotorcraft analysis (CAMRAD) and flight-test data. The impact of blade dynamics on blade section lift-coefficient time histories is studied by comparing predictions from a rigid-blade analysis and an elastic-blade analysis with helicopter flight test data. The elastic blade analysis better predicts high-frequency behavior of section lift. In addition, components of the blade angle of attack such as elastic blade twist, blade flap rate, blade slope velocity, and inflow are examined as a function of blade mode. Elastic blade motion changed blade angle of attack by a few tenths of a degree, and up to the sixth rotor harmonic. A similar study of the influence of blade dynamics on bending and torsion moments was also conducted. A correlation study comparing predictions from several elastic-blade analyses with flight-test data revealed that an elastic-blade model consisting of only three elastic bending modes (first and second flap and first lag), and two elastic torsion modes was sufficient for good correlation.

  4. VELOCITIES AND STREAMLINES ON A BLADE-TO-BLADE STREAM SURFACE OF A TURBOMACHINE

    NASA Technical Reports Server (NTRS)

    Katsanis, T.

    1994-01-01

    This program is a revision of an existing program for blade-to-blade aerodynamic analysis of turbomachine blades and it is a simpler program while consistent with related programs. The analysis is for two-dimensional, subsonic, compressible (or incompressible), nonviscous flow in a circular or straight infinite cascade of blades, which may be fixed or rotating. The flow may be axial, radial, or mixed, and the stream channel thickness may change in the through-flow direction. The program input consists of blade and stream channel geometry, total flow conditions, inlet and outlet flow angles, and blade-to-blade stream channel weight flow. The output includes blade surface velocities, velocity magnitude and direction at all interior mesh points in the blade-to-blade passage, and streamline coordinates throughout the passage. This program was developed on an IBM 7094/7044 DCS.

  5. Adjoint Methods for Adjusting Three-Dimensional Atmosphere and Surface Properties to Fit Multi-Angle Multi-Pixel Polarimetric Measurements

    NASA Technical Reports Server (NTRS)

    Martin, William G.; Cairns, Brian; Bal, Guillaume

    2014-01-01

    This paper derives an efficient procedure for using the three-dimensional (3D) vector radiative transfer equation (VRTE) to adjust atmosphere and surface properties and improve their fit with multi-angle/multi-pixel radiometric and polarimetric measurements of scattered sunlight. The proposed adjoint method uses the 3D VRTE to compute the measurement misfit function and the adjoint 3D VRTE to compute its gradient with respect to all unknown parameters. In the remote sensing problems of interest, the scalar-valued misfit function quantifies agreement with data as a function of atmosphere and surface properties, and its gradient guides the search through this parameter space. Remote sensing of the atmosphere and surface in a three-dimensional region may require thousands of unknown parameters and millions of data points. Many approaches would require calls to the 3D VRTE solver in proportion to the number of unknown parameters or measurements. To avoid this issue of scale, we focus on computing the gradient of the misfit function as an alternative to the Jacobian of the measurement operator. The resulting adjoint method provides a way to adjust 3D atmosphere and surface properties with only two calls to the 3D VRTE solver for each spectral channel, regardless of the number of retrieval parameters, measurement view angles or pixels. This gives a procedure for adjusting atmosphere and surface parameters that will scale to the large problems of 3D remote sensing. For certain types of multi-angle/multi-pixel polarimetric measurements, this encourages the development of a new class of three-dimensional retrieval algorithms with more flexible parametrizations of spatial heterogeneity, less reliance on data screening procedures, and improved coverage in terms of the resolved physical processes in the Earth?s atmosphere.

  6. Structural integrity design for an active helicopter rotor blade with piezoelectric flap actuators

    NASA Astrophysics Data System (ADS)

    Lee, Jaehwan; Shin, SangJoon

    2011-04-01

    Helicopter uses a rotor system to generate lift, thrust and forces, and its aerodynamic environment is generally complex. Unsteady aerodynamic environment arises such as blade vortex interaction. This unsteady aerodynamic environment induces vibratory aerodynamic loads and high aeroacoustic noise. The aerodynamic load and aeroacoustic noise is at N times the rotor blade revolutions (N/rev). But conventional rotor control system composed of pitch links and swash plate is not capable of adjusting such vibratory loads because its control is restricted to 1/rev. Many active control methodologies have been examined to alleviate the problem. The blade using active control device manipulates the blade pitch angle with N/rev. In this paper, Active Trailing-edge Flap blade, which is one of the active control methods, is designed to reduce the unsteady aerodynamic loads. Active Trailing-edge Flap blade uses a trailing edge flap manipulated by an actuator to change camber line of the airfoil. Piezoelectric actuators are installed inside the blade to manipulate the trailing edge flap.

  7. Composite-Blade Structural Analyzer

    NASA Technical Reports Server (NTRS)

    Aiello, R. A.; Chamis, C. C.

    1992-01-01

    COBSTRAN (COmposite Blade STRuctural ANalyzer) computer program is preprocessor and postprocessor facilitating design and analysis of composite turbofan and turboprop blades, and of composite wind-turbine blades. Combines theories of mechanics of composites and of laminates with data base of fiber and matrix properties. Designed to carry out linear analyses required for efficient mathematical modeling and analysis of bladelike structural components made of multilayered angle-plied fiber composites. Components made from isotropic or anisotropic homogeneous materials also modeled. Written in FORTRAN 77.

  8. The measurement of boundary layers on a compressor blade in cascade at high positive incidence angle. 1: Experimental techniques and results

    NASA Technical Reports Server (NTRS)

    Deutsch, S.; Zierke, W. C.

    1986-01-01

    Measurements of the mean velocity and turbulence intensity were made using a one-component laser Doppler velocimeter in the boundary layer and near wake about a double circular arc, compressor blade in cascade. The measurements were made at a chord Reynolds number of 500,000. Boundary layer measurements on the pressure surface indicate a transition region over the last 40% of the chord. A small separation bubble near the leading edge of the suction surface results in an immediate transition from laminar to turbulent flow. The non-equilibrium turbulent boundary layer separates near the trailing edge of the suction surface. Similarity of the outer region of the turbulent boundary layer ceases to exist in the separated region. Also, similarity does not hold in the near-wake region, a region which includes negative mean velocities because of the separation near the trailing edge on the suction surface.

  9. Aerodynamic tests of Darrieus wind turbine blades

    SciTech Connect

    Migliore, P.G.; Walters, R.E.; Wolfe, W.P.

    1983-03-01

    An indoor facility for the aerodynamic testing of Darrieus turbine blades was developed. Lift, drag, and moment coefficients were measured for two blades whose angle of attack and chord-to-radius ratio were varied. The first blade used an NACA 0015 airfoil section; the second used a 15% elliptical cross section with a modified circular arc trailing edge. Blade aerodynamic coefficients were corrected to section coefficients for comparison to published rectilinear flow data. Although the airfoil sections were symmetrical, moment coefficients were not zero and the lift and drag curves were asymmetrical about zero lift coefficient and angle of attack. These features verified the predicted virtual camber and incidence phenomena. Boundary-layer centrifugal effects were manifested by discontinuous lift curves and large differences in the angle of zero lift between th NACA 0015 and elliptical airfoils. It was concluded that rectilinear flow aerodynamic data are not applicable to Darrieus turbine blades, even for small chord-to-radius ratios.

  10. Digital resolver for helicopter model blade motion analysis

    NASA Technical Reports Server (NTRS)

    Daniels, T. S.; Berry, J. D.; Park, S.

    1992-01-01

    The paper reports the development and initial testing of a digital resolver to replace existing analog signal processing instrumentation. Radiometers, mounted directly on one of the fully articulated blades, are electrically connected through a slip ring to analog signal processing circuitry. The measured signals are periodic with azimuth angle and are resolved into harmonic components, with 0 deg over the tail. The periodic nature of the helicopter blade motion restricts the frequency content of each flapping and yaw signal to the fundamental and harmonics of the rotor rotational frequency. A minicomputer is employed to collect these data and then plot them graphically in real time. With this and other information generated by the instrumentation, a helicopter test pilot can then adjust the helicopter model's controls to achieve the desired aerodynamic test conditions.

  11. The effect of an adjustable sitting angle on the perceived discomfort from the back and neck-shoulder regions in building crane operators.

    PubMed

    Gustafson-Söderman, U

    1987-12-01

    In a previous working environment study of building crane operators, it has been found that approximately 70% experienced discomfort from the locomotor system. Comments by the interviewed crane operators indicated that it is, among other things, the forward flexed sitting position during lifts close to the crane that causes discomfort. This investigation sought to apply knowledge from the forestry industry concerning the beneficial effects of improved operator's seats to the work situation of crane operators. On a construction site with three cranes, an operator's seat with adjustable sitting angle was installed in one of the cranes. Estimation of perceived strain-discomfort in the lumbar region of the back as well as in the neck-shoulder region was assessed according to Borg's scale. Data were collected from the crane operators seated in their ordinary operator's seat, seated in the test seat, and seated in another crane with an ordinary type of seat. The results showed that in [Formula: see text] of all lifts, the crane operator was sitting bent-forward with little opportunity for relief via a backrest or armrests. The highest estimated discomfort values in the study were also obtained in an ordinary operator's seat on days with a high proportion of lifts close to the crane. When working in the test seat, none of the subjects gave an estimate higher than 0.5 (discomfort equivalent to very, very weak). An adjustable operator's seat could be a good alternative to a fixed seat, and more tests would be desirable. PMID:15676634

  12. Rotorcraft Blade-Vortex Interaction Controller

    NASA Technical Reports Server (NTRS)

    Schmitz, Fredric H. (Inventor)

    1995-01-01

    Blade-vortex interaction noises, sometimes referred to as 'blade slap', are avoided by increasing the absolute value of inflow to the rotor system of a rotorcraft. This is accomplished by creating a drag force which causes the angle of the tip-path plane of the rotor system to become more negative or more positive.

  13. Blade feathering system for wind turbines

    SciTech Connect

    Harner, K.I.; Patrick, J.P.; Vosseller, K.F.

    1984-07-31

    A blade feathering system for wind turbines includes a feather actuator, control means operatively connected thereto and an adjustment means operatively connected to the control means for selectively varying the rate of operation of the feather actuator for feathering the wind turbine blades at a variable rate.

  14. Turbine blade friction damping study

    NASA Technical Reports Server (NTRS)

    Dominic, R. J.

    1985-01-01

    A lumped parameter method, implemented on a VAX 11/780 computer shows that the primary parameters affecting the performance of the friction damper of the first stage turbine of the SSME high pressure fuel pump are: the damper-blade coefficient of friction; the normal force applied to the friction interface; the amplitude of the periodic forcing function; the relative phase angle of the forcing functions for adjacent blades bridged by a damper (effectively, the engine order of the forcing function); and the amount of hysteretic damping that acts to limit the vibration amplitude of the blade in its resonance modes. The low order flexural resonance vibration modes of HPFTP blades without dampers, with production dampers, and with two types of lightweight experimental dampers were evaluated in high speed spin pit tests. Results agree with those of the analytical study in that blades fitted with production friction dampers experienced the airfoil-alone flexural resonance mode, while those without dampers or with lighter weight dampers did not. No blades fitted with dampers experienced the whole blade flexural resonance mode during high speed tests, while those without dampers did.

  15. Counterrotating aircraft propulsor blades

    NASA Technical Reports Server (NTRS)

    Nelson, Joey L. (Inventor); Elston, III, Sidney B. (Inventor); Tseng, Wu-Yang (Inventor); Hemsworth, Martin C. (Inventor)

    1993-01-01

    A propulsor blade for an aircraft engine includes an airfoil section formed in the shape of a scimitar. A metallic blade spar is interposed between opposed surfaces of the blade and is bonded to the surfaces to establish structural integrity of the blade. The metallic blade spar includes a root end allowing attachment of the blade to the engine.

  16. Counterrotating aircraft propulsor blades

    NASA Technical Reports Server (NTRS)

    Nelson, Joey L. (Inventor); Elston, III, Sidney B. (Inventor); Tseng, Wu-Yang (Inventor); Hemsworth, Martin C. (Inventor)

    1988-01-01

    A propulsor blade for an aircraft engine includes an airfoil section formed in the shape of a scimitar. A metallic blade spar is interposed between opposed surfaces of the blade and is bonded to the surfaces to establish structural integrity of the blade. The metallic blade spar includes a root end allowing attachment of the blade to the engine.

  17. Influence of pitch, twist, and taper on a blade`s performance loss due to roughness

    SciTech Connect

    Tangler, J.L.

    1996-12-31

    The purpose of this study was to determine the influence of blade geometric parameters such as pitch, twist, and taper on a blade`s sensitivity to leading edge roughness. The approach began with an evaluation of available test data of performance degradation due to roughness effects for several rotors. In addition to airfoil geometry, this evaluation suggested that a rotor`s sensitivity to roughness was also influenced by the blade geometric parameters. Parametric studies were conducted using the PROP computer code with wind-tunnel airfoil characteristics for smooth and rough surface conditions to quantify the performance loss due to roughness for tapered and twisted blades relative to a constant-chord, non-twisted blade at several blade pitch angles. The results indicate that a constant-chord, non-twisted blade pitched toward stall will have the greatest losses due to roughness. The use of twist, taper, and positive blade pitch angles all help reduce the angle-of-attack distribution along the blade for a given wind speed and the associated performance degradation due to roughness. 8 refs., 6 figs.

  18. Two-dimensional cold-air cascade study of a film-cooled turbine stator blade. 4: Comparison of experimental and analytical aerodynamic results for blade with 12 rows of 0.076-centimeter-(0.030-inch-) diameter holes having streamwise ejection angles

    NASA Technical Reports Server (NTRS)

    Prust, H. W., Jr.

    1978-01-01

    Previously published experimental aerodynamic efficiency results for a film cooled turbine stator blade are compared with analytical results computed from two published analytical methods. One method was used as published; the other was modified for certain cases of coolant discharge from the blade suction surface. For coolant ejection from blade surface regions where the surface static pressures are higher than the blade exit pressure, both methods predict the experimental results quite well. However, for ejection from regions with surface static pressures lower than the blade exit pressure, both methods predict too small a change in efficiency. The modified method gives the better prediction.

  19. Load attenuating passively adaptive wind turbine blade

    DOEpatents

    Veers, Paul S.; Lobitz, Donald W.

    2003-01-01

    A method and apparatus for improving wind turbine performance by alleviating loads and controlling the rotor. The invention employs the use of a passively adaptive blade that senses the wind velocity or rotational speed, and accordingly modifies its aerodynamic configuration. The invention exploits the load mitigation prospects of a blade that twists toward feather as it bends. The invention includes passively adaptive wind turbine rotors or blades with currently preferred power control features. The apparatus is a composite fiber horizontal axis wind-turbine blade, in which a substantial majority of fibers in the blade skin are inclined at angles of between 15 and 30 degrees to the axis of the blade, to produces passive adaptive aeroelastic tailoring (bend-twist coupling) to alleviate loading without unduly jeopardizing performance.

  20. Load attenuating passively adaptive wind turbine blade

    DOEpatents

    Veers, Paul S.; Lobitz, Donald W.

    2003-01-07

    A method and apparatus for improving wind turbine performance by alleviating loads and controlling the rotor. The invention employs the use of a passively adaptive blade that senses the wind velocity or rotational speed, and accordingly modifies its aerodynamic configuration. The invention exploits the load mitigation prospects of a blade that twists toward feather as it bends. The invention includes passively adaptive wind turbine rotors or blades with currently preferred power control features. The apparatus is a composite fiber horizontal axis wind-turbine blade, in which a substantial majority of fibers in the blade skin are inclined at angles of between 15 and 30 degrees to the axis of the blade, to produces passive adaptive aeroelastic tailoring (bend-twist coupling) to alleviate loading without unduly jeopardizing performance.

  1. Rotating blade vibration analysis using shells

    NASA Technical Reports Server (NTRS)

    Leissa, A. W.; Lee, J. K.; Wang, A. J.

    1981-01-01

    Shallow shell theory and the Ritz method are employed to determine the frequencies and mode shapes of turbomachinery blades having both camber and twist, rotating with non-zero angles of attack. Frequencies obtained for different degrees of shallowness and thickness are compared with results available in the literature, obtained from finite element analyses of nonrotating blades. Frequencies are also determined for a rotating blade, showing the effects of changing the (1) angular velocity of rotation, (2) disk radius and (3) angle of attack, as well as the significance of the most important body force terms.

  2. Variable diameter wind turbine rotor blades

    DOEpatents

    Jamieson, Peter McKeich; Hornzee-Jones, Chris; Moroz, Emilian M.; Blakemore, Ralph W.

    2005-12-06

    A system and method for changing wind turbine rotor diameters to meet changing wind speeds and control system loads is disclosed. The rotor blades on the wind turbine are able to adjust length by extensions nested within or containing the base blade. The blades can have more than one extension in a variety of configurations. A cable winching system, a hydraulic system, a pneumatic system, inflatable or elastic extensions, and a spring-loaded jack knife deployment are some of the methods of adjustment. The extension is also protected from lightning by a grounding system.

  3. Shaft adjuster

    DOEpatents

    Harry, Herbert H.

    1989-01-01

    Apparatus and method for the adjustment and alignment of shafts in high power devices. A plurality of adjacent rotatable angled cylinders are positioned between a base and the shaft to be aligned which when rotated introduce an axial offset. The apparatus is electrically conductive and constructed of a structurally rigid material. The angled cylinders allow the shaft such as the center conductor in a pulse line machine to be offset in any desired alignment position within the range of the apparatus.

  4. Method of calculating blade-to-blade plane flow in centrifugal pump

    NASA Technical Reports Server (NTRS)

    Jackson, E. D.

    1970-01-01

    Steam filament solution determines velocity distribution due to potential flow in the blade-to-blade plane of the radial impeller. This is used to determine the mass-averaged relative fluid angle, which is in turn used in an axisymmetric program to obtain steam surfaces of the assumed axisymmetric flow.

  5. VELOCITIES AND STREAMLINES ON A BLADE-TO-BLADE STREAM SURFACE OF A TANDEM BLADE TURBOMACHINE

    NASA Technical Reports Server (NTRS)

    Katsanis, T.

    1994-01-01

    This computer program gives the blade-to-blade solution of the two-dimensional, subsonic, compressible (or incompressible), nonviscous flow problem for a circular or straight infinite cascade of tandem or slotted turbomachine blades. The blades may be fixed or rotating. The flow may be axial, radial , or mixed. The method of solution is based on the stream function using an iterative solution of nonlinear finite-difference equations. These equations are solved using two major levels of iteration. The inner iteration consists of the solution of simultaneous linear equations by successive over-relaxation, using an estimated optimum over-relaxation factor. The outer iteration then changes the coefficients of the simultaneous equations to correct for compressibility. The program input consists of the basic blade geometry, the meridional stream channel coordinates, fluid stagnation conditions, weight flow and flow split through the slot, and inlet and outlet flow angles. The output includes blade surface velocities, velocity magnitude and direction throughout the passage, and the streamline coordinates.

  6. Ceramic blade attachment system

    DOEpatents

    Boyd, G.L.

    1995-04-11

    A retainer ring is arranged to mount turbine blades to a turbine disk so that aerodynamic forces produced by a gas turbine engine are transferred from the turbine blades to the turbine disk to cause the turbine blades and turbine disk to rotate, but so that centrifugal forces of the turbine blades resulting from the rotation of the turbine blades and turbine disk are not transferred from the turbine blades to the turbine disk. 6 figures.

  7. Ceramic blade attachment system

    DOEpatents

    Boyd, Gary L.

    1995-01-01

    A retainer ring is arranged to mount turbine blades to a turbine disk so that aerodynamic forces produced by a gas turbine engine are transferred from the turbine blades to the turbine disk to cause the turbine blades and turbine disk to rotate, but so that centrifugal forces of the turbine blades resulting from the rotation of the turbine blades and turbine disk are not transferred from the turbine blades to the turbine disk.

  8. Numerical simulation on the aerodynamic effects of blade icing on small scale Straight-bladed VAWT

    NASA Astrophysics Data System (ADS)

    Feng, Fang; Li, Shengmao; Li, Yan; Tian, Wenqiang

    To invest the effects of blade surface icing on the aerodynamics performance of the straight-bladed vertical-axis wind turbine (SB-VAWT), wind tunnel tests were carried out on a static straight blade using a simple icing wind tunnel. Firstly, the icing situations on blade surface at some kinds of typical attack angle were observed and recorded under different cold water flow fluxes. Then the iced blade airfoils were combined into a SB-VAWT model with two blades. Numerical simulations were carried out on this model, and the static and dynamic torque coefficients of the model with and without icing were computed. Both the static and dynamic torque coefficients were decreased for the icing effects.

  9. Gravitropic basis of leaf blade nastic curvatures

    NASA Technical Reports Server (NTRS)

    Hayes, A. B.

    1982-01-01

    The curvatures produced in leaf blades by auxin treatment have been described as nastic curvatures because the initial differential growth is always enhanced on the lower side, regardless of the side of application. It is now known, however, that blades can show differential growth of either the upper or the lower side depending on the conditions of treatment. The dorsiventrality of the blade therefore influences but does not limit the direction of curvature. The dorsiventral directionality of response to growth regulators and the response to changes in the orientation to gravity are seen as indicating that blade curvatures are analogous to negative or positive gravitropism. It is noted that neither blade hyponasty or epinasty can be accounted for by ethylene alone. Petiole responses, however, are not directional, and the leaf angle changes induced by rotation or auxin treatment can be accounted for by ethylene production.

  10. TSONIC- TRANSONIC VELOCITIES ON A BLADE-TO-BLADE STREAM SURFACE OF A TURBOMACHINE

    NASA Technical Reports Server (NTRS)

    Katsanis, T.

    1994-01-01

    This program obtains a transonic flow solution on a blade-to-blade surface between blades of a turbomachine. The flow must be essentially subsonic, but there may be locally supersonic flow. The solution is two-dimensional, isentropic, and shock free. The blades may be fixed or rotating. The flow may be axial, radial, or mixed, and there may be a change in stream-channel thickness in the through-flow direction. A loss in relative stagnation pressure may be accounted for. The program input consists of blade and stream-channel geometry, stagnation flow conditions, inlet and outlet flow angles, and blade-to-blade stream-channel weight flow. The output includes blade surface velocities, velocity magnitude and direction at all interior mesh points in the blade-to-blade passage, and streamline coordinates throughout the passage. The transonic solution is obtained by a combination of a finite-difference, stream-function solution and a velocity-gradient solution. The finite-difference solution at a reduced weight flow provides information needed to obtain a velocity-gradient solution. This program is written in FORTRAN IV for batch execution and has been implemented on the IBM 360 computer with a central memory requirement of approximately 36K of 8 bit bytes. This program was developed in 1969 and last updated in 1979.

  11. Report of tests of a compressor configuration of DCA blading

    NASA Astrophysics Data System (ADS)

    Himes, S. J.

    1983-06-01

    Results of an experimental program to measure the performance of a compressor stator cascade consisting of 20 double-circular-arc (DCA) blades of chord 5.01 inches, aspect ratio 2.0 and solidity 1.67 under conditions of varying incidence angle and Reynolds number are reported. Flow quality and blade performance data were obtained using pneumatic probe surveys and surface pressure measurements. Changes in Reynolds numbers in the range of 500,000 to 770,000 did not measurably affect either flow quality or blade performance. Changes in incidence angle over the range -15 to 10 degrees produced generally well behaved blade performance parameters.

  12. Computations of flows over a turbine blade

    NASA Astrophysics Data System (ADS)

    Amano, R. S.; Xu, C.

    2009-09-01

    To meet the needs of efficient turbine blade designs, computational fluid dynamics (CFD) predictions of a complex three-dimensional (3D) flow field in turbine blade passages have been incorporated in the design process during the last decade. Owing to the numerous advantages possessed by a 3D CFD technology, many industries already use a 3D blading technique in the design process of turbomachines. In addition, blade lean and sweep have been implemented to increase the blade row efficiency. Experimental studies have shown some advantages of these features. However, most of the experimental results were combined with other features together as well, thus making it difficult to determine the effects of individual superior features. The development of CFD techniques has made it possible to do 3D turbulent flow analyses in a very short time. In this study, numerical studies are presented to demonstrate the sweep effects on a transonic compressor airfoil. The purpose of this study is to investigate the sweep effects without changing other compressor blade features, i.e., keeping the blade outflow angles and section shapes to be the same at design sections for all cases. Through this study, the sweep effect in a transonic compressor rotor blade was tested. The results showed that the sweeps redistribute the flow reducing the secondary flow loss, depending on the baseline. It was shown that the forward sweep reduces the tip loading in terms of the static pressure coefficient.

  13. Eulerian laser Doppler vibrometry: Online blade damage identification on a multi-blade test rotor

    NASA Astrophysics Data System (ADS)

    Oberholster, A. J.; Heyns, P. S.

    2011-01-01

    Laser Doppler vibrometry enables the telemetry-free measurement of online turbomachinery blade vibration. Specifically, the Eulerian or fixed reference frame implementation of laser vibrometry provides a practical solution to the condition monitoring of rotating blades. The short data samples that are characteristic of this measurement approach do however negate the use of traditional frequency domain signal processing techniques. It is therefore necessary to employ techniques such as time domain analysis and non-harmonic Fourier analysis to obtain useful information from the blade vibration signatures. The latter analysis technique allows the calculation of phase angle trends which can be used as indicators of blade health deterioration, as has been shown in previous work for a single-blade rotor. This article presents the results from tests conducted on a five-blade axial-flow test rotor at different rotor speeds and measurement positions. With the aid of artificial neural networks, it is demonstrated that the parameters obtained from non-harmonic Fourier analysis and time domain signal processing on Eulerian laser Doppler vibrometry signals can successfully be used to identify and quantify blade damage from among healthy blades. It is also shown that the natural frequencies of individual blades can be approximated from the Eulerian signatures recorded during rotor run-up and run-down.

  14. COBSTRAN - COMPOSITE BLADE STRUCTURAL ANALYZER

    NASA Technical Reports Server (NTRS)

    Aiello, R. A.

    1994-01-01

    The COBSTRAN (COmposite Blade STRuctural ANalyzer) program is a pre- and post-processor that facilitates the design and analysis of composite turbofan and turboprop blades, as well as composite wind turbine blades. COBSTRAN combines composite mechanics and laminate theory with a data base of fiber and matrix properties. As a preprocessor for NASTRAN or another Finite Element Method (FEM) program, COBSTRAN generates an FEM model with anisotropic homogeneous material properties. Stress output from the FEM program is provided as input to the COBSTRAN postprocessor. The postprocessor then uses the composite mechanics and laminate theory routines to calculate individual ply stresses, strains, interply stresses, thru-the-thickness stresses and failure margins. COBSTRAN is designed to carry out the many linear analyses required to efficiently model and analyze blade-like structural components made of multilayered angle-plied fiber composites. Components made from isotropic or anisotropic homogeneous materials can also be modeled as a special case of COBSTRAN. NASTRAN MAT1 or MAT2 material cards are generated according to user supplied properties. COBSTRAN is written in FORTRAN 77 and was implemented on a CRAY X-MP with a UNICOS 5.0.12 operating system. The program requires either COSMIC NASTRAN or MSC NASTRAN as a structural analysis package. COBSTRAN was developed in 1989, and has a memory requirement of 262,066 64 bit words.

  15. Turbine blade tip flow discouragers

    DOEpatents

    Bunker, Ronald Scott

    2000-01-01

    A turbine assembly comprises a plurality of rotating blade portions in a spaced relation with a stationery shroud. The rotating blade portions comprise a root section, a tip portion and an airfoil. The tip portion has a pressure side wall and a suction side wall. A number of flow discouragers are disposed on the blade tip portion. In one embodiment, the flow discouragers extend circumferentially from the pressure side wall to the suction side wall so as to be aligned generally parallel to the direction of rotation. In an alternative embodiment, the flow discouragers extend circumferentially from the pressure side wall to the suction side wall so as to be aligned at an angle in the range between about 0.degree. to about 60.degree. with respect to a reference axis aligned generally parallel to the direction of rotation. The flow discouragers increase the flow resistance and thus reduce the flow of hot gas flow leakage for a given pressure differential across the blade tip portion so as to improve overall turbine efficiency.

  16. Analysis of rotating flexible blades using MSC/NASTRAN

    NASA Technical Reports Server (NTRS)

    Ernst, Michael A.

    1988-01-01

    An overview is given of the use of MSC/NASTRAN in the analysis of rotating flexible blades. The geometrically nonlinear analysis using NASTRAN Solution Sequence 64 is discussed along with the determination of frequencies and mode shapes using Solution Sequence 63. Items unique to rotating blade analysis, such as setting angle, centrifugal softening effects, and hub flexibility, are emphasized.

  17. Turbine blade damping study

    NASA Technical Reports Server (NTRS)

    Dominic, R. J.

    1984-01-01

    Research results and progress on the performance of bladed systems is reported the different topics discussed include: the study of turbine blade damping; forced vibrations of friction damped beam moistures in two dimensions; and a users manual for a computer program for dynamic analysis of bladed systems.

  18. Fully three-dimensional and viscous semi-inverse method for axial/radial turbomachine blade design

    NASA Astrophysics Data System (ADS)

    Ji, Min

    2008-10-01

    various loading strategies for the mixed flow impeller. It is demonstrated that uniformity of impeller exit flow and performance gain can be achieved with appropriate loading combinations at hub and shroud. An application of this semi-inverse method is also demonstrated through a redesign of an industrial shrouded subsonic centrifugal impeller. The redesigned impeller shows improved performance and operating range from the original one. Preliminary studies of blade designs presented in this work show that through the choice of the prescribed pressure loading profiles, this semi-inverse method can be used to design blade with the following objectives: (1) Various operating envelope. (2) Uniformity of impeller exit flow. (3) Overall performance improvement. By designing blade geometry with the proposed semi-inverse method whereby the blade pressure loading is specified instead of the conventional design approach of manually adjusting the blade angle to achieve blade design objectives, designers can discover blade geometry design space that has not been explored before.

  19. Angle detector

    NASA Technical Reports Server (NTRS)

    Parra, G. T. (Inventor)

    1978-01-01

    An angle detector for determining a transducer's angular disposition to a capacitive pickup element is described. The transducer comprises a pendulum mounted inductive element moving past the capacitive pickup element. The capacitive pickup element divides the inductive element into two parts L sub 1 and L sub 2 which form the arms of one side of an a-c bridge. Two networks R sub 1 and R sub 2 having a plurality of binary weighted resistors and an equal number of digitally controlled switches for removing resistors from the networks form the arms of the other side of the a-c bridge. A binary counter, controlled by a phase detector, balances the bridge by adjusting the resistance of R sub 1 and R sub 2. The binary output of the counter is representative of the angle.

  20. FORTRAN program for calculating leading and trailing-edge geometry of turbomachine blades

    NASA Technical Reports Server (NTRS)

    Schumann, L. F.

    1977-01-01

    A FORTRAN IV program which calculates leading- and trailing-edge circle radii, tangency angles on the leading- and trailing-edge circles, and stagger angles of turbomachinery blade sections using only spline points defining the blade surfaces is described. The program shifts the origin of the blade coordinates to the leading edge of the blade. Required input includes (m, theta) coordinates of a sufficient number of spline points to adequately define the two surfaces of the blade. Other required input are the radii from the axis of rotation of the leading- and trailing-edges. The output from this program is used directly as the geometrical input for a NASA developed program for calculating transonic velocities on a blade-to-blade stream surface of a turbomachine. The program is used for axial, radial, and mixed flow turbomachine blades.

  1. Parametric study of turbine blade platform friction damping using the lumped parameter analysis

    NASA Technical Reports Server (NTRS)

    Dominic, R. J.

    1984-01-01

    The hardware configuration used in the present study of turbine blade planform friction damping, by means of the lumped parameter analysis, is the first turbine stage of the Space Shuttle Main Engine's High Pressure Fuel Turbopump. The analysis procedure solves the nonlinear equations of motion for a turbine blade that is acted on by a platform friction damper, using an iterative matrix method. Attention is given to the effects on blade deflection response of variations in friction coefficient, the normal force on the friction surface interface, blade hysteretic damping, the blade-to-blade phase angle of the harmonic forcing function, and the amplitude of the forcing function.

  2. Micromachined cutting blade formed from {211}-oriented silicon

    DOEpatents

    Fleming, James G.; Fleming, legal representative, Carol; Sniegowski, Jeffry J.; Montague, Stephen

    2011-08-09

    A cutting blade is disclosed fabricated of micromachined silicon. The cutting blade utilizes a monocrystalline silicon substrate having a {211} crystalline orientation to form one or more cutting edges that are defined by the intersection of {211} crystalline planes of silicon with {111} crystalline planes of silicon. This results in a cutting blade which has a shallow cutting-edge angle .theta. of 19.5.degree.. The micromachined cutting blade can be formed using an anisotropic wet etching process which substantially terminates etching upon reaching the {111} crystalline planes of silicon. This allows multiple blades to be batch fabricated on a common substrate and separated for packaging and use. The micromachined cutting blade, which can be mounted to a handle in tension and optionally coated for increased wear resistance and biocompatibility, has multiple applications including eye surgery (LASIK procedure).

  3. Sweep-twist adaptive rotor blade : final project report.

    SciTech Connect

    Ashwill, Thomas D.

    2010-02-01

    Knight & Carver was contracted by Sandia National Laboratories to develop a Sweep Twist Adaptive Rotor (STAR) blade that reduced operating loads, thereby allowing a larger, more productive rotor. The blade design used outer blade sweep to create twist coupling without angled fiber. Knight & Carver successfully designed, fabricated, tested and evaluated STAR prototype blades. Through laboratory and field tests, Knight & Carver showed the STAR blade met the engineering design criteria and economic goals for the program. A STAR prototype was successfully tested in Tehachapi during 2008 and a large data set was collected to support engineering and commercial development of the technology. This report documents the methodology used to develop the STAR blade design and reviews the approach used for laboratory and field testing. The effort demonstrated that STAR technology can provide significantly greater energy capture without higher operating loads on the turbine.

  4. Impact behavior of filament wound graphite/epoxy fan blades

    NASA Technical Reports Server (NTRS)

    Bowles, K. J.

    1978-01-01

    The fabrication and impact tests of graphite/epoxy filament wound fan blades are discussed. Blades which were spin tested at tip speeds up to 305 meters per second retained their structural integrity. Two blades were each impacted with a 454 gram slice of a 908 gram simulated bird at a tip speed of 263 meters per second and impact angles of 22 and 32 deg. The impact tests were recorded with high-speed movie film. The blade which was impacted at 22 deg sustained some root delamination but remained intact. The 32 deg impact separated the blade from the root. No local damage other than leading edge debonding was observed for either blade. Results of a failure mode analysis are also discussed.

  5. Micromachined cutting blade formed from {211}-oriented silicon

    DOEpatents

    Fleming, James G.; Sniegowski, Jeffry J.; Montague, Stephen

    2003-09-09

    A cutting blade is disclosed fabricated of micromachined silicon. The cutting blade utilizes a monocrystalline silicon substrate having a {211} crystalline orientation to form one or more cutting edges that are defined by the intersection of {211} crystalline planes of silicon with {111} crystalline planes of silicon. This results in a cutting blade which has a shallow cutting-edge angle .theta. of 19.5.degree.. The micromachined cutting blade can be formed using an anisotropic wet etching process which substantially terminates etching upon reaching the {111} crystalline planes of silicon. This allows multiple blades to be batch fabricated on a common substrate and separated for packaging and use. The micromachined cutting blade, which can be mounted to a handle in tension and optionally coated for increased wear resistance and biocompatibility, has multiple applications including eye surgery (LASIK procedure).

  6. Methods and apparatus for twist bend coupled (TCB) wind turbine blades

    DOEpatents

    Moroz, Emilian Mieczyslaw; LeMieux, David Lawrence; Pierce, Kirk Gee

    2006-10-10

    A method for controlling a wind turbine having twist bend coupled rotor blades on a rotor mechanically coupled to a generator includes determining a speed of a rotor blade tip of the wind turbine, measuring a current twist distribution and current blade loading, and adjusting a torque of a generator to change the speed of the rotor blade tip to thereby increase an energy capture power coefficient of the wind turbine.

  7. Establishing Age-Adjusted Reference Ranges for Iris-Related Parameters in Open Angle Eyes with Anterior Segment Optical Coherence Tomography

    PubMed Central

    Peterson, Jeffrey R.; Blieden, Lauren S.; Chuang, Alice Z.; Baker, Laura A.; Rigi, Mohammed; Feldman, Robert M.; Bell, Nicholas P.

    2016-01-01

    Purpose Define criteria for iris-related parameters in an adult open angle population as measured with swept source Fourier domain anterior segment optical coherence tomography (ASOCT). Methods Ninety-eight eyes of 98 participants with open angles were included and stratified into 5 age groups (18–35, 36–45, 46–55, 56–65, and 66–79 years). ASOCT scans with 3D mode angle analysis were taken with the CASIA SS-1000 (Tomey Corporation, Nagoya, Japan) and analyzed using the Anterior Chamber Analysis and Interpretation software. Anterior iris surface length (AISL), length of scleral spur landmark (SSL) to pupillary margin (SSL-to-PM), iris contour ratio (ICR = AISL/SSL-to-PM), pupil radius, radius of iris centroid (RICe), and iris volume were measured. Outcome variables were summarized for all eyes and age groups, and mean values among age groups were compared using one-way analysis of variance. Stepwise regression analysis was used to investigate demographic and ocular characteristic factors that affected each iris-related parameter. Results Mean (±SD) values were 2.24 mm (±0.46), 4.06 mm (±0.27), 3.65 mm (±0.48), 4.16 mm (±0.47), 1.14 (±0.04), 1.51 mm2 (±0.23), and 38.42 μL (±4.91) for pupillary radius, RICe, SSL-to-PM, AISL, ICR, iris cross-sectional area, and iris volume, respectively. Both pupillary radius (P = 0.002) and RICe (P = 0.027) decreased with age, while SSL-to-PM (P = 0.002) and AISL increased with age (P = 0.001). ICR (P = 0.54) and iris volume (P = 0.49) were not affected by age. Conclusion This study establishes reference values for iris-related parameters in an adult open angle population, which will be useful for future studies examining the role of iris changes in pathologic states. PMID:26815917

  8. An aerodynamic study on flexed blades for VAWT applications

    NASA Astrophysics Data System (ADS)

    Micallef, Daniel; Farrugia, Russell; Sant, Tonio; Mollicone, Pierluigi

    2014-12-01

    There is renewed interest in aerodynamics research of VAWT rotors. Lift type, Darrieus designs sometimes use flexed blades to have an 'egg-beater shape' with an optimum Troposkien geometry to minimize the structural stress on the blades. While straight bladed VAWTs have been investigated in depth through both measurements and numerical modelling, the aerodynamics of flexed blades has not been researched with the same level of detail. Two major effects may have a substantial impact on blade performance. First, flexing at the equator causes relatively strong trailing vorticity to be released. Secondly, the blade performance at each station along the blade is influenced by self-induced velocities due to bound vorticity. The latter is not present in a straight bladed configuration. The aim of this research is to investigate these effects in relation to an innovative 4kW wind turbine concept being developed in collaboration with industry known as a self-adjusting VAWT (or SATVAWT). The approach used in this study is based on experimental and numerical work. A lifting line free-wake vortex model was developed. Wind tunnel power and hot-wire velocity measurements were performed on a scaled down, 60cm high, three bladed model in a closed wind tunnel. Results show a substantial axial wake induction at the equator resulting in a lower power generation at this position. This induction increases with increasing degree of flexure. The self-induced velocities caused by blade bound vorticity at a particular station was found to be relatively small.

  9. Flow visualizations of perpendicular blade vortex interactions

    NASA Technical Reports Server (NTRS)

    Rife, Michael C.; Davenport, William J.

    1992-01-01

    Helium bubble flow visualizations have been performed to study perpendicular interaction of a turbulent trailing vortex and a rectangular wing in the Virginia Tech Stability Tunnel. Many combinations of vortex strength, vortex-blade separation (Z(sub s)) and blade angle of attack were studied. Photographs of representative cases are presented. A range of phenomena were observed. For Z(sub s) greater than a few percent chord the vortex is deflected as it passes the blade under the influence of the local streamline curvature and its image in the blade. Initially the interaction appears to have no influence on the core. Downstream, however, the vortex core begins to diffuse and grow, presumably as a consequence of its interaction with the blade wake. The magnitude of these effects increases with reduction in Z(sub s). For Z(sub s) near zero the form of the interaction changes and becomes dependent on the vortex strength. For lower strengths the vortex appears to split into two filaments on the leading edge of the blade, one passing on the pressure and one passing on the suction side. At higher strengths the vortex bursts in the vicinity of the leading edge. In either case the core of its remnants then rapidly diffuse with distance downstream. Increase in Reynolds number did not qualitatively affect the flow apart from decreasing the amplitude of the small low-frequency wandering motions of the vortex. Changes in wing tip geometry and boundary layer trip had very little effect.

  10. Blade Manufacturing Improvement: Remote Blade Manufacturing Demonstration

    SciTech Connect

    ASHWILL, THOMAS D.

    2003-05-01

    The objective of this program was to investigate manufacturing improvements for wind turbine blades. The program included a series of test activities to evaluate the strength, deflection, performance, and loading characteristics of the prototype blades. The original contract was extended in order to continue development of several key blade technologies identified in the project. The objective of the remote build task was to demonstrate the concept of manufacturing wind turbine blades at a temporary manufacturing facility in a rural environment. TPI Composites successfully completed a remote manufacturing demonstration in which four blades were fabricated. The remote demonstration used a manufacturing approach which relied upon material ''kits'' that were organized in the factory and shipped to the site. Manufacturing blades at the wind plant site presents serious logistics difficulties and does not appear to be the best approach. A better method appears to be regional manufacturing facilities, which will eliminate most of the transportation cost, without incurring the logistical problems associated with fabrication directly onsite. With this approach the remote facilities would use commonly available industrial infrastructure such as enclosed workbays, overhead cranes, and paved staging areas. Additional fatigue testing of the M20 root stud design was completed with good results. This design provides adhesive bond strength under fatigue loading that exceeds that of the fastener. A new thru-stud bonding concept was developed for the M30 stud design. This approach offers several manufacturing advantages; however, the test results were inconclusive.

  11. Interdependence of centrifugal compressor blade geometry and relative flow field

    NASA Astrophysics Data System (ADS)

    Krain, H.

    1985-03-01

    The influence of the impeller blade geometry on the calculated relative flow field has been studied by means of an impeller design program available at DFVLR (Krain, 1984). Several geometrical parameters were varied, however, the meridional channel geometry was always kept constant. By this approach the blade wrap angle has been found to react significantly on the relative flow which is illustrated by comparing two designs with different wrap angles. Primarily in the hub/leading edge area a better boundary layer flow connected with a reduction of blade loading was obtained by increasing the wrap angle. But also in the shroud/pressure side area the increased blade looping attributed to an additional flow stabilization.

  12. Ceramic blade attachment system

    DOEpatents

    Shaffer, James E.

    1995-01-01

    A turbine blade having a preestablished rate of thermal expansion is attached to a turbine disc having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the turbine blade and forms a turbine assembly. The turbine blade has a root portion defining a pair of sides having a pair of grooves therein. The turbine assembly includes a pair of flanges between which the turbine blades are positioned. Each of the pair of flanges has a plurality of grooves defined therein. The grooves within the pair of flanges are aligned with the grooves in the blades and have a space formed therebetween. A plurality of spherical balls are positioned within the space. The plurality of spherical balls has a preestablished rate of thermal expansion being equal to the preestablished rate of thermal expansion of the turbine blade.

  13. Ceramic blade attachment system

    DOEpatents

    Shaffer, J.E.

    1995-07-11

    A turbine blade having a preestablished rate of thermal expansion is attached to a turbine disc having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the turbine blade and forms a turbine assembly. The turbine blade has a root portion defining a pair of sides having a pair of grooves therein. The turbine assembly includes a pair of flanges between which the turbine blades are positioned. Each of the pair of flanges has a plurality of grooves defined therein. The grooves within the pair of flanges are aligned with the grooves in the blades and have a space formed therebetween. A plurality of spherical balls are positioned within the space. The plurality of spherical balls has a preestablished rate of thermal expansion being equal to the preestablished rate of thermal expansion of the turbine blade. 4 figs.

  14. STAEBL/General composites with hygrothermal effects (STAEBL/GENCOM). [Structural Tailoring of Engine Blades

    NASA Technical Reports Server (NTRS)

    Rubinstein, R.

    1988-01-01

    A computer code has been developed to perform structural optimization of turbine blades made from angle ply fiber composite laminates. Design variables available for optimization include geometric parameters such as blade thickness disribution and root chord, and composite material parameters such as ply angles and numbers of plies of each constituent material. Design constraints include resonance margins, forced response margins, maximum stress, and maximum ply combined stress. A general description of this code is given. Design optimization studies for typical blades are presented.

  15. Rotor blade dynamic design

    NASA Technical Reports Server (NTRS)

    Pritchard, Jocelyn I.; Adelman, Howard M.; Mantay, Wayne R.

    1989-01-01

    The rotor dynamic design considerations are essentially limitations on the vibratory response of the blades which in turn limit the dynamic excitation of the fuselage by forces and moments transmitted to the hub. Quantities which are associated with the blade response and which are subject to design constraints are discussed. These include blade frequencies, vertical and inplane hub shear, rolling and pitching moments, and aeroelastic stability margin.

  16. Automatic efficiency optimization of an axial compressor with adjustable inlet guide vanes

    NASA Astrophysics Data System (ADS)

    Li, Jichao; Lin, Feng; Nie, Chaoqun; Chen, Jingyi

    2012-04-01

    The inlet attack angle of rotor blade reasonably can be adjusted with the change of the stagger angle of inlet guide vane (IGV); so the efficiency of each condition will be affected. For the purpose to improve the efficiency, the DSP (Digital Signal Processor) controller is designed to adjust the stagger angle of IGV automatically in order to optimize the efficiency at any operating condition. The A/D signal collection includes inlet static pressure, outlet static pressure, outlet total pressure, rotor speed and torque signal, the efficiency can be calculated in the DSP, and the angle signal for the stepping motor which control the IGV will be sent out from the D/A. Experimental investigations are performed in a three-stage, low-speed axial compressor with variable inlet guide vanes. It is demonstrated that the DSP designed can well adjust the stagger angle of IGV online, the efficiency under different conditions can be optimized. This establishment of DSP online adjustment scheme may provide a practical solution for improving performance of multi-stage axial flow compressor when its operating condition is varied.

  17. Propeller blade retention system

    NASA Technical Reports Server (NTRS)

    Elston, III, Sidney B. (Inventor); Simon, III, Victor H. (Inventor); Tseng, Wu-Yang (Inventor); Butler, Lawrence (Inventor)

    1993-01-01

    The invention concerns the mounting of propeller blades to a ring-shaped rotor. The blades are of the variable pitch type, and the shank of each blade extends through a respective hole in the rotor. Each hole contains an annular shelf which is fastened to the wall of the hole and surrounds each shank. Each shank bears a pair of bearing races which sandwich the annular shelf in order to connect the blade to the rotor. Bearing rollers are positioned between the annular shelf and the bearing races.

  18. Functional consequences of tooth design: effects of blade shape on energetics of cutting.

    PubMed

    Anderson, Philip S L; LaBarbera, Michael

    2008-11-01

    Dental structures capture, retain and fragment food for ingestion. Gnathostome dentition should be viewed in the context of the prey's material properties. Animal muscle and skin are mechanically tough materials that resist fragmentation unless energy is continually supplied directly to the tip of the fracture by some device such as a blade edge. Despite the variety of bladed tooth morphologies in gnathostomes, few studies have experimentally examined the effects of different blade designs on cutting efficiency. We tested the effects of blades with and without contained notches and in a 'fang' configuration on the force and energy required to fracture raw, unprocessed biological tissues (fish and shrimp) using a double guillotine device. Blade design strongly affects the work required to fragment biological tissues. A notched blade reduced the work to fracture of tissues tested by up to 600 J m(-2) (50% reduction). The specific angle of the notch had a significant effect, with acute angles more effectively reducing work to fracture. A bladed triangle matched to a notch reduced work to fracture more than a notch-straight blade pair. Strain patterns seen while cutting photoelastic gelatin indicate that the reduction in work to fracture with triangular and notched blades arises from a combination of 'trapping ability' and blade approach angle causing the material to fracture at lower overall strain levels. These results show that the notched blade designs found in a wide variety of vertebrate dentitions reduce the energy expenditure (and presumably handling time) when cutting tough prey materials like animal flesh. PMID:18978227

  19. Heat Transfer on a Film-Cooled Rotating Blade

    NASA Technical Reports Server (NTRS)

    Garg, Vijay K.

    1999-01-01

    A multi-block, three-dimensional Navier-Stokes code has been used to compute heat transfer coefficient on the blade, hub and shroud for a rotating high-pressure turbine blade with 172 film-cooling holes in eight rows. Film cooling effectiveness is also computed on the adiabatic blade. Wilcox's k-omega model is used for modeling the turbulence. Of the eight rows of holes, three are staggered on the shower-head with compound-angled holes. With so many holes on the blade it was somewhat of a challenge to get a good quality grid on and around the blade and in the tip clearance region. The final multi-block grid consists of 4784 elementary blocks which were merged into 276 super blocks. The viscous grid has over 2.2 million cells. Each hole exit, in its true oval shape, has 80 cells within it so that coolant velocity, temperature, k and omega distributions can be specified at these hole exits. It is found that for the given parameters, heat transfer coefficient on the cooled, isothermal blade is highest in the leading edge region and in the tip region. Also, the effectiveness over the cooled, adiabatic blade is the lowest in these regions. Results for an uncooled blade are also shown, providing a direct comparison with those for the cooled blade. Also, the heat transfer coefficient is much higher on the shroud as compared to that on the hub for both the cooled and the uncooled cases.

  20. AERODYNAMIC AND BLADING DESIGN OF MULTISTAGE AXIAL FLOW COMPRESSORS

    NASA Technical Reports Server (NTRS)

    Crouse, J. E.

    1994-01-01

    The axial-flow compressor is used for aircraft engines because it has distinct configuration and performance advantages over other compressor types. However, good potential performance is not easily obtained. The designer must be able to model the actual flows well enough to adequately predict aerodynamic performance. This computer program has been developed for computing the aerodynamic design of a multistage axial-flow compressor and, if desired, the associated blading geometry input for internal flow analysis. The aerodynamic solution gives velocity diagrams on selected streamlines of revolution at the blade row edges. The program yields aerodynamic and blading design results that can be directly used by flow and mechanical analysis codes. Two such codes are TSONIC, a blade-to-blade channel flow analysis code (COSMIC program LEW-10977), and MERIDL, a more detailed hub-to-shroud flow analysis code (COSMIC program LEW-12966). The aerodynamic and blading design program can reduce the time and effort required to obtain acceptable multistage axial-flow compressor configurations by generating good initial solutions and by being compatible with available analysis codes. The aerodynamic solution assumes steady, axisymmetric flow so that the problem is reduced to solving the two-dimensional flow field in the meridional plane. The streamline curvature method is used for the iterative aerodynamic solution at stations outside of the blade rows. If a blade design is desired, the blade elements are defined and stacked within the aerodynamic solution iteration. The blade element inlet and outlet angles are established by empirical incidence and deviation angles to the relative flow angles of the velocity diagrams. The blade element centerline is composed of two segments tangentially joined at a transition point. The local blade angle variation of each element can be specified as a fourth-degree polynomial function of path distance. Blade element thickness can also be specified

  1. Fan blade protection system

    NASA Technical Reports Server (NTRS)

    Hermans, Thomas C. (Inventor); Wakeman, Thomas G. (Inventor); Hauser, Ambrose A. (Inventor)

    1993-01-01

    In one type of aircraft propulsion system, propeller blades are mounted on a ring which surrounds a turbine. An annular space exists between the turbine and the ring. If a propeller blade should break free, the unbalanced centrifugal load tends to deform the ring. The invention reduces the deformation, as by locating spacers between the turbine and the ring.

  2. Composite wind turbine blades

    NASA Astrophysics Data System (ADS)

    Ong, Cheng-Huat

    Researchers in wind energy industry are constantly moving forward to develop higher efficiency wind turbine. One major component for wind turbine design is to have cost effective wind turbine blades. In addition to correct aerodynamic shape and blade geometry, blade performance can be enhanced further through aero-elastic tailoring design and material selections. An analytical tool for blade design has been improved and validated. This analytical tool is utilized to resolve issues related to elastic tailoring design. The investigation looks into two major issues related to the design and fabrication of a bend-twist-coupled blade. Various design parameters for a blade such as materials, laminate lay-up, skin thickness, ply orientation, internal spar, etc. have been examined for designing a bend-twist-coupled blade. The parametric study indicates that the critical design parameters are the ply material, the ply orientation, and the volume fraction ratio between the anisotropic layers and orthotropic layers. To produce a blade having the bend-twist coupling characteristics, the fiber lay-ups at the top and bottom skins of the blade must have a "mirror" lay-up in relation to the middle plane of the blade. Such lay-up causes fiber discontinuation at the seam. The joint design at the seam is one major consideration in fabricating a truly anisotropic blade. A new joint design was proposed and tensile failure tests were carried out for both the old and new joint designs. The tests investigated the effects of different types of joint designs, the laminate lay-up at the joints, and the stacking sequence of the joint retention strength. A major component of a wind turbine blade, D-spar, was designed to maximum coupling. Two D-spars were then fabricated using the new joint design; one of them was subjected to both static and modal testings. Traditionally, wind turbine blades are made of low cost glass material; however, carbon fibers are proposed as alternative material. Our

  3. Unsteady potential flow past a propeller blade section

    NASA Technical Reports Server (NTRS)

    Takallu, M. A.

    1990-01-01

    An analytical study was conducted to predict the effect of an oscillating stream on the time dependent sectional pressure and lift coefficients of a model propeller blade. The assumption is that as the blade sections encounter a wake, the actual angles of attack vary in a sinusoidal manner through the wake, thus each blade is exposed to an unsteady stream oscillating about a mean value at a certain reduced frequency. On the other hand, an isolated propeller at some angle of attack can experience periodic changes in the value of the flow angle causing unsteady loads on the blades. Such a flow condition requires the inclusion of new expressions in the formulation of the unsteady potential flow around the blade sections. These expressions account for time variation of angle of attack and total shed vortices in the wake of each airfoil section. It was found that the final expressions for the unsteady pressure distribution on each blade section are periodic and that the unsteady circulation and lift coefficients exhibit a hysteresis loop.

  4. Structural dynamic modeling and stability of a rotating blade under gravitational force

    NASA Astrophysics Data System (ADS)

    Kwon, Seungmin; Chung, Jintai; Hee Yoo, Hong

    2013-05-01

    Turbine blade lengths have been increasing in recent wind energy system designs in order to enhance power generation capacity. A longer blade length makes the structural system more flexible and often results in an undesirable, large dynamic response, which should be avoided in the design of the system. In the present study, the equations of motion of a rotating wind turbine blade undergoing gravitational force are derived, while considering tilt and pitch angles. Since the gravitational force acting on the rotating blade creates an oscillating axial force, this results in oscillating stiffness terms in the governing equations. The validity of the derived rotating blade model is evaluated by comparing its transient responses to those obtained by using a commercial finite element code. Effects of rotating speed, tilt angle, and pitch angle of the wind turbine blade on its dynamic stability characteristics are investigated.

  5. Turbine blade platform seal

    DOEpatents

    Zagar, Thomas W.; Schiavo, Anthony L.

    2001-01-01

    A rotating blade group 90 for a turbo-machine having an improved device for sealing the gap 110 between the edges 112,114 of adjacent blade platforms 96,104. The gap 110 between adjacent blades 92,100 is sealed by a seal pin 20 its central portion 110 and by a seal plate 58,60 at each of the front 54 and rear 56 portions. The seal plates 58,60 are inserted into corresponding grooves 62,64 formed in the adjacent edges 112,114 of adjoining blades 92,100 and held in place by end plates 40,42. The end of the seal plates 58,60 may be chamfered 78,80 to improve the seal against the end plate 40,42. The seal pin 20 provides the required damping between the blades 92,100 and the seal plates 58,60 provide improved sealing effectiveness.

  6. Ceramic blade attachment system

    DOEpatents

    Shaffer, James E.

    1995-01-01

    A turbine blade having a preestablished rate of thermal expansion is attached to a turbine wheel having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the turbine blade. The turbine blade has a root portion having a first groove and a second groove therein. The turbine wheel includes a plurality of openings in which the turbine blade is positioned. Each of the openings has a first groove and a second groove therein. The space or void formed between the first grooves and the second grooves has a plurality of spherical balls positioned therein. The plurality of spherical balls has a preestablished rate of thermal expansion being equal to the preestablished rate of thermal expansion of the turbine blade.

  7. Ceramic blade attachment system

    DOEpatents

    Shaffer, J.E.

    1995-01-10

    A turbine blade having a preestablished rate of thermal expansion is attached to a turbine wheel having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the turbine blade. The turbine blade has a root portion having a first groove and a second groove therein. The turbine wheel includes a plurality of openings in which the turbine blade is positioned. Each of the openings has a first groove and a second groove therein. The space or void formed between the first grooves and the second grooves has a plurality of spherical balls positioned therein. The plurality of spherical balls has a preestablished rate of thermal expansion being equal to the preestablished rate of thermal expansion of the turbine blade. 4 figures.

  8. Two-dimensional cold-air cascade study of a film-cooled turbine stator blade. 5: Comparison of experimental and analytical aerodynamic results for blade with 12 rows of 0.038-centimeter-(0.015 inch) diameter coolant holes having streamwise ejection angles

    NASA Technical Reports Server (NTRS)

    Prust, H. W., Jr.

    1978-01-01

    Published experimental aerodynamic efficiency results were compared with results predicted from two published analytical methods. This is the second of two such comparisons. One of the analytical methods was used as published; the other was modified for certain cases of coolant discharge from the blade suction surface. The results show that for 23 cases of single row and multirow discharge covering coolant fractions from 0 to about 9 percent, the difference between the experimental and predicted results was no greater than about 1 percent in any case and less than 1/2 percent in most cases.

  9. Investigation on impeller radial force for double-suction centrifugal pump with staggered blade arrangement

    NASA Astrophysics Data System (ADS)

    Zhang, Z. C.; Wang, F. J.; Yao, Z. F.; Leng, H. F.; Zhou, P. J.

    2013-12-01

    In order to find the effects of blade arrangement on impeller radial force, a double-suction centrifugal pump with two impeller configurations is investigated by using CFD approach. The two impeller have same geometry, same blade number, and different blade arrangement. One is staggered impeller in which the blades are arranged with half of blade phase angle staggered in circular direction, another is traditional symmetrical impeller with symmetrical blade arrangement. Results show that the radial force vector diagram for symmetrical impeller is a hexagonal, while it is nearly a circle for staggered impeller. The staggered impeller results no radial force saltation which exists in symmetrical impeller. The blade passing frequency dominates the radial force fluctuation in symmetrical impeller, while this frequency is almost not existed in staggered impeller. The results indicate that staggered blade arrangement can significantly reduce radial force fluctuation in double-suction centrifugal pump.

  10. Turbine blades and systems with forward blowing slots

    SciTech Connect

    Zuteck, Michael D.; Zalusky, Leigh; Lees, Paul

    2015-09-15

    A blade for use in a wind turbine comprises a pressure side and suction side meeting at a trailing edge and leading edge. The pressure side and suction side provide lift to the turbine blade upon the flow of air from the leading edge to the trailing edge and over the pressure side and suction side. The blade includes one or more openings at the suction side, in some cases between the leading edge and the trailing edge. The one or more openings are configured to provide a pressurized fluid towards the leading edge of the blade, in some cases at an angle between about 0.degree. and 70.degree. with respect to an axis oriented from a centerline of the blade toward the leading edge.

  11. Investigation of rotor blade roughness effects on turbine performance

    NASA Technical Reports Server (NTRS)

    Boynton, J. L.; Tabibzadeh, R.; Hudson, S. T.

    1992-01-01

    The cold air test program was completed on the SSME (Space Shuttle Main Engine) HPFTP (High Pressure Fuel Turbopump) turbine with production nozzle vane rings and polished coated rotor blades with a smooth surface finish of 30 microinch (0.76 micrometer) RMS (Root Mean Square). The smooth blades were polished by an abrasive flow machining process. The test results were compared with the air test results from production rough coated rotor blades with a surface finish of up to 400 microinch (10.16 micrometer) RMS. Turbine efficiency was higher for the smooth blades over the entire range tested. Efficiency increased 2.1 percentage points at the SSME 104 percent RPL (Rated Power Level) condition. This efficiency improvement could reduce the SSME HPFTP turbine inlet temperature by 57 degrees Rankine (32 degrees Kelvin) increasing turbine durability. The turbine flow parameter increased and the mid-span outlet swirl angle became more axial with the smooth rotor blades.

  12. Wind turbine blade construction

    SciTech Connect

    Basso, R.J.

    1988-03-01

    This patent describes a blade for the rotor of a wind turbine or the like having a root end mounted on the rotor and extending generally radially outwardly from the rotor out to a distal end comprising: (a) a cuff at the root end of the blade for mounting on the rotor, and having a generally cylindrical, radially outwardly directed collar; (b) a generally cylindrical reinforcing strut mounted generally coaxially to the collar, and extending radially outwardly from the rotor throughout a portion of the length of the blade; (c) a hollow spar coaxially mounted around the strut and extending substantially the full length of the blade; (d) an elongated, rigid aerodynamic skin defining the exterior, wind-encountering surfaces of the blade, and being mounted over and bonded to the strut and defining the distal end of the blade; (e) the reinforcing strut being of decreasing diameter toward the distal end of the blade; and (f) the reinforcing strut comprising telescoping tubes of graduated length with the larger diameter tubes being longer than the smaller diameter tubes.

  13. Analysis of helicopter blade vortex structure by laser velocimetry

    NASA Astrophysics Data System (ADS)

    Boutier, A.; Lefèvre, J.; Micheli, F.

    1996-05-01

    In descent flight, helicopter external noise is mainly generated by the Blade Vortex Interaction (BVI). To under-stand the dynamics of this phenomenon, the vortex must be characterized before its interaction with the blade, which means that its viscous core radius, its strength and its distance to the blade have to be determined by non-intrusive measurement techniques. As part of the HART program (Higher Harmonic Control Aeroacoustic Rotor Test, jointly conducted by US Army, NASA, DLR, DNW and ONERA), a series of tests have been made in the German Dutch Wind Tunnel (DNW) on a helicopter rotor with 2 m long blades, rotating at 1040 rpm; several flight configurations, with an advance ratio of 0.15 and a shaft angle of 5.3°, have been studied with different higher harmonic blade pitch angles superposed on the conventional one (corresponding to the baseline case). The flow on the retreating side has been analyzed with an especially designed 3D laser velocimeter, and, simultaneously, the blade tip attitude has been determined in order to get the blade-vortex miss distance, which is a crucial parameter in the noise reduction. A 3D laser velocimeter, in backscatter mode with a working distance of 5 m, was installed on a platform 9 m high, and flow seeding with submicron incense smoke was achieved in the settling chamber using a remotely controlled displacement device. Acquisition of instantaneous velocity vectors by an IFA 750 yielded mean velocity and turbulence maps across the vortex as well as the vortex position, intensity and viscous radius. The blade tip attitude (altitude, jitter, angle of incidence) was recorded by the TART method (Target Attitude in Real Time) which makes use of a CCD camera on which is formed the image of two retroreflecting targets attached to the blade tip and lighted by a flash lamp. In addition to the mean values of the aforementioned quantities, spectra of their fluctuations have been established up to 8 Hz.

  14. Study of casing treatment stall margin improvement phenomena. [for compressor rotor blade tips compressor blades rotating stalls

    NASA Technical Reports Server (NTRS)

    Prince, D. C., Jr.; Wisler, D. C.; Hilvers, D. E.

    1974-01-01

    The results of a program of experimental and analytical research in casing treatments over axial compressor rotor blade tips are presented. Circumferential groove, axial-skewed slot, and blade angle slot treatments were tested. These yielded, for reduction in stalling flow and loss in peak efficiency, 5.8% and 0 points, 15.3% and 2.0 points, and 15.0% and 1.2 points, respectively. These values are consistent with other experience. The favorable stalling flow situations correlated well with observations of higher-then-normal surface pressures on the rotor blade pressure surfaces in the tip region, and with increased maximum diffusions on the suction surfaces. Annular wall pressure gradients, especially in the 50-75% chord region, are also increased and blade surface pressure loadings are shifted toward the trailing edge for treated configurations. Rotor blade wakes may be somewhat thinner in the presence of good treatments, particularly under operating conditions close to the baseline stall.

  15. Comparison of calculated and experimental cascade performance for controlled-diffusion compressor stator blading

    NASA Technical Reports Server (NTRS)

    Sanger, N. L.; Shreeve, R. P.

    1986-01-01

    The mid-span section of a previously reported controlled-diffusion compressor stator has been experimentally evaluated in cascade. Measurements are taken over a range of incidence angles for blade chord Reynolds numbers from 470,000 to 690,000. Blade chord length is 12.7 cm, aspect ratio is 2.0, and solidity is 1.67. Measurements include conventional cascade performance parameters as well as blade surface pressures. Computations are made for the inviscid flow field, surface boundary layers, and loss for several of the blade inlet angle conditions, are compared against corresponding data.

  16. Effect of Hardness Combination on Contact Deformation of Center Bevel Blade with Counter Plate Subjected to a Pushing Load

    NASA Astrophysics Data System (ADS)

    Chaijit, Seksan; Nagasawa, Shigeru; Fukuzawa, Yasushi; Murayama, Mitsuhiro; Katayama, Isamu

    This paper reports on the contact mechanism between the crushing tip of a center bevel blade and the dent of a counter plate. Pushing tests of the blade on the counter plate were carried out experimentally and numerically by varying the mechanical flow properties of both the blade tip and the counter plate. A yield line force ratio β was proposed to characterize the contact deformation in terms of blade apex angle. Through this research, it was found that: (1) the crushed tip of a mild blade could be kept in moderate for the mild counter plate; (2) the counter plate's dent depth is linearly related to the β and depends on the combination of the mechanical properties of both the blade and the counter plate; (3) the total clearance of the deformed tools is almost independent from the tools material combination; (4) the profile angle of the blade tip and the crushed tip thickness mainly depend on the blade's properties.

  17. Experimental research of reaction blading on air turbine VT-400

    NASA Astrophysics Data System (ADS)

    Klimko, Marek; Okresa, Daniel

    2016-03-01

    The article deals with testing a reaction blading on an experimental air turbine VT-400, which is situated at the Department of Power System Engineering at University of West Bohemia. Experiments were carried out in cooperation with an industrial partner Doosan Skoda Power. The outputs of these measurements are for example: results of the stage efficiency depending on the speed ratio u/c, the course of reaction, the input and output angles and profile losses along a blade.

  18. Vibrational analyses of cracked pre-twisted blades

    NASA Astrophysics Data System (ADS)

    Chen, L. W.; Jeng, C. H.

    1993-01-01

    A finite element model is utilized to analyze the vibrational behavior of a pre-twisted rotating blade with a single edge crack. This model can satisfy both geometric boundary conditions and natural boundary conditions of the blade. The effects of the transverse shear deformation, rotary inertia and the pre-twisted angle are taken into account. The influences of the crack location and the crack size on natural frequencies, buckling loads and dynamic instability regions are studied. It is found that a crack has great influences on these dynamic characteristics of the rotating blade.

  19. A NASTRAN primer for the analysis of rotating flexible blades

    NASA Technical Reports Server (NTRS)

    Lawrence, Charles; Aiello, Robert A.; Ernst, Michael A.; Mcgee, Oliver G.

    1987-01-01

    This primer provides documentation for using MSC NASTRAN in analyzing rotating flexible blades. The analysis of these blades includes geometrically nonlinear (large displacement) analysis under centrifugal loading, and frequency and mode shape (normal modes) determination. The geometrically nonlinear analysis using NASTRAN Solution sequence 64 is discussed along with the determination of frequencies and mode shapes using Solution Sequence 63. A sample problem with the complete NASTRAN input data is included. Items unique to rotating blade analyses, such as setting angle and centrifugal softening effects are emphasized.

  20. Effectiveness enhancement of a cycloidal wind turbine by individual active control of blade motion

    NASA Astrophysics Data System (ADS)

    Hwang, In Seong; Lee, Yun Han; Kim, Seung Jo

    2007-04-01

    In this paper, a research for the effectiveness enhancement of a Cycloidal Wind Turbine by individual active control of blade motion is described. To improve the performance of the power generation system, which consists of several straight blades rotating about axis in parallel direction, the cycloidal blade system and the individual active blade control method are adopted. It has advantages comparing with horizontal axis wind turbine or conventional vertical axis wind turbine because it maintains optimal blade pitch angles according to wind speed, wind direction and rotor rotating speed to produce high electric power at any conditions. It can do self-starting and shows good efficiency at low wind speed and complex wind condition. Optimal blade pitch angle paths are obtained through CFD analysis according to rotor rotating speed and wind speed. The individual rotor blade control system consists of sensors, actuators and microcontroller. To realize the actuating device, servo motors are installed to each rotor blade. Actuating speed and actuating force are calculated to compare with the capacities of servo motor, and some delays of blade pitch angles are corrected experimentally. Performance experiment is carried out by the wind blowing equipment and Labview system, and the rotor rotates from 50 to 100 rpm according to the electric load. From this research, it is concluded that developing new vertical axis wind turbine, Cycloidal Wind Turbine which is adopting individual active blade pitch control method can be a good model for small wind turbine in urban environment.

  1. Innovative design approaches for large wind turbine blades

    NASA Astrophysics Data System (ADS)

    Jackson, K. J.; Zuteck, M. D.; van Dam, C. P.; Standish, K. J.; Berry, D.

    2005-04-01

    A preliminary design study of an advanced 50 m blade for utility wind turbines is presented and discussed. The effort was part of the Department of Energy WindPACT Blade System Design Study with the goal to investigate and evaluate design and manufacturing issues for wind turbine blades in the 1-10 MW size range. Two different blade designs are considered and compared in this article. The first is a fibreglass design, while the second design selectively incorporates carbon fibre in the main structural elements. The addition of carbon results in modest cost increases and provides significant benefits, particularly with respect to blade deflection. The structural efficiency of both designs was maximized by tailoring the thickness of the blade cross-sections to simplify the construction of the internal members. Inboard the blades incorporate thick blunt trailing edge aerofoils (flatback aerofoils), while outboard more conventional sharp trailing edge high-lift aerofoils are used. The outboard section chord lengths were adjusted to yield the least complex and costly internal blade structure. A significant portion of blade weight is related to the root buildup and metal hardware for typical root attachment designs. The results show that increasing the number of studs has a positive effect on total weight, because it reduces the required root laminate thickness. The aerodynamic performance of the blade aerofoils was predicted using computational techniques that properly simulate blunt trailing edge flows. The performance of the rotor was predicted assuming both clean and soiled blade surface conditions. The rotor is shown to provide excellent performance at a weight significantly lower than that of current rotors of this size. Copyright

  2. Blade attachment assembly

    DOEpatents

    Garcia-Crespo, Andres Jose; Delvaux, John McConnell; Miller, Diane Patricia

    2016-05-03

    An assembly and method for affixing a turbomachine rotor blade to a rotor wheel are disclosed. In an embodiment, an adaptor member is provided disposed between the blade and the rotor wheel, the adaptor member including an adaptor attachment slot that is complementary to the blade attachment member, and an adaptor attachment member that is complementary to the rotor wheel attachment slot. A coverplate is provided, having a coverplate attachment member that is complementary to the rotor wheel attachment slot, and a hook for engaging the adaptor member. When assembled, the coverplate member matingly engages with the adaptor member, and retains the blade in the adaptor member, and the assembly in the rotor wheel.

  3. Ceramic blade attachment system

    DOEpatents

    Boyd, Gary L.

    1994-01-01

    A turbine blade having a preestablished rate of thermal expansion is attached to a turbine wheel having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the turbine blade. The turbine blade has a root portion having a pair of recessed portions thereon. The turbine wheel includes a plurality of openings in which the turbine blade is positioned. Each of the openings have a pair of grooves therein in which are positioned a pair of pins having a generally rectangular cross-section and a reaction surface thereon. A pair of cylindrical rollers interposed respective ones of the pair of reaction surfaces and the pair of recessed portions. The attachment system or turbine assembly provides an economical, reliable and effective attachment of a component having a preestablished rate of thermal expansion to a component having a greater preestablished rate of thermal expansion.

  4. Ceramic blade attachment system

    DOEpatents

    Boyd, G.L.

    1994-12-13

    A turbine blade having a preestablished rate of thermal expansion is attached to a turbine wheel having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the turbine blade. The turbine blade has a root portion having a pair of recessed portions thereon. The turbine wheel includes a plurality of openings in which the turbine blade is positioned. Each of the openings have a pair of grooves therein in which are positioned a pair of pins having a generally rectangular cross-section and a reaction surface thereon. A pair of cylindrical rollers interposed respective ones of the pair of reaction surfaces and the pair of recessed portions. The attachment system or turbine assembly provides an economical, reliable and effective attachment of a component having a preestablished rate of thermal expansion to a component having a greater preestablished rate of thermal expansion. 3 figures.

  5. Blade Testing Trends (Presentation)

    SciTech Connect

    Desmond, M.

    2014-08-01

    As an invited guest speaker, Michael Desmond presented on NREL's NWTC structural testing methods and capabilities at the 2014 Sandia Blade Workshop held on August 26-28, 2014 in Albuquerque, NM. Although dynamometer and field testing capabilities were mentioned, the presentation focused primarily on wind turbine blade testing, including descriptions and capabilities for accredited certification testing, historical methodology and technology deployment, and current research and development activities.

  6. An experimental investigation of the flap-lag stability of a hingeless rotor with comparable levels of hub and blade stiffness in hovering flight

    NASA Technical Reports Server (NTRS)

    Curtiss, H. C., Jr.; Putman, W. F.

    1976-01-01

    An experimental investigation of the flap-lag stability of a hingeless rotor in hovering flight is presented and discussed. The rotor blade and hub configuration were selected such that the hub and blade had comparable levels of bending stiffness. Experimental measurements of the lag damping were made for various values of rotor rotational speed and blade pitch angle. Specifically at a blade pitch angle of 8 deg at three-quarters radius, the lag damping was determined over a range of rotational speeds from 200 RPM to 320 RPM and also over a range of blade pitch angles from 0 deg to 8 deg.

  7. An experimental investigation of the helicopter rotor blade element airloads on a model rotor in the blade stall regime

    NASA Technical Reports Server (NTRS)

    Fisher, R. K., Jr.; Tompkins, J. E.; Bobo, C. J.; Child, R. F.

    1971-01-01

    A wind tunnel test program was conducted on an eight foot diameter model rotor system to determine blade element airloads characteristics in the unstalled and stalled flight regimes. The fully articulated model rotor system utilized three blades with a Vertol 23010-1.58 airfoil section, the blades being 1/7.5 scale models of the Ch-47C rotor blades. Instrumentation was incorporated at the blade 75% radial station to measure pressure and skin friction distributions, surface streamline directions and local angle of attack. The test program was conducted in three phases; non-rotating, hover and forward flight at advance ratios of 0.15, 0.35 and 0.60. Test data were analyzed with respect to providing insight to the mechanisms affecting blade stall, particularly retreating blade stall during forward flight conditions. From such data, an assessment was made as to the applicability of current theoretical analyses used for the prediction of blade element airloads in the stall regime.

  8. Experimental performance and acoustic investigation of modern, counterrotating blade concepts

    NASA Technical Reports Server (NTRS)

    Hoff, G. E.

    1990-01-01

    The aerodynamic, acoustic, and aeromechanical performance of counterrotating blade concepts were evaluated both theoretically and experimentally. Analytical methods development and design are addressed. Utilizing the analytical methods which evolved during the conduct of this work, aerodynamic and aeroacoustic predictions were developed, which were compared to NASA and GE wind tunnel test results. The detailed mechanical design and fabrication of five different composite shell/titanium spar counterrotating blade set configurations are presented. Design philosophy, analyses methods, and material geometry are addressed, as well as the influence of aerodynamics, aeromechanics, and aeroacoustics on the design procedures. Blade fabrication and quality control procedures are detailed; bench testing procedures and results of blade integrity verification are presented; and instrumentation associated with the bench testing also is identified. Additional hardware to support specialized testing is described, as are operating blade instrumentation and the associated stress limits. The five counterrotating blade concepts were scaled to a tip diameter of 2 feet, so they could be incorporated into MPS (model propulsion simulators). Aerodynamic and aeroacoustic performance testing was conducted in the NASA Lewis 8 x 6 supersonic and 9 x 15 V/STOL (vertical or short takeoff and landing) wind tunnels and in the GE freejet anechoic test chamber (Cell 41) to generate an experimental data base for these counterrotating blade designs. Test facility and MPS vehicle matrices are provided, and test procedures are presented. Effects on performance of rotor-to-rotor spacing, angle-of-attack, pylon proximity, blade number, reduced-diameter aft blades, and mismatched rotor speeds are addressed. Counterrotating blade and specialized aeromechanical hub stability test results are also furnished.

  9. SSME blade damper technology

    NASA Technical Reports Server (NTRS)

    Kielb, Robert E.; Griffin, Jerry H.

    1987-01-01

    Before 1975 turbine blade damper designs were based on experience and very simple mathematical models. Failure of the dampers to perform as expected showed the need to gain a better understanding of the physical mechanism of friction dampers. Over the last 10 years research on friction dampers for aeronautical propulsion systems has resulted in methods to optimize damper designs. The first-stage turbine blades on the Space Shuttle Main Engine (SSME) high-pressure oxygen pump have experienced cracking problems due to excessive vibration. A solution is to incorporate a well-designed friction dampers to attenuate blade vibration. The subject study, a cooperative effort between NASA Lewis and Carnegie-Mellon University, represents an application of recently developed friction damper technology to the SSME high-pressure oxygen turbopump. The major emphasis was the contractor's design known as the two-piece damper. Damping occurs at the frictional interface between the top half of the damper and the underside of the platforms of the adjacent blades. The lower half of the damper is an air seal to retard airflow in the volume between blade necks.

  10. Ceramic blade attachment system

    DOEpatents

    Frey, G.A.; Jimenez, O.D.

    1996-12-03

    A turbine blade having a preestablished rate of thermal expansion is attached to a turbine flange having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the turbine blade. The turbine flange includes a first upstanding flange and a second upstanding flange having a groove formed between them. The turbine flange further includes a recess. Each of the first and second upstanding flanges have a plurality of bores therein. A turbine blade has a first member and a second member positioned in one of the groove and the recess. Each of the first member and the second member have a plurality of bores therein. A pin is positioned in respective ones of the plurality of bores in the first and second upstanding members and the first and second members and attach the blade to the turbine flange. The pin has a preestablished rate of thermal expansion being substantially equal to the rate of thermal expansion of the blade. 4 figs.

  11. Ceramic blade attachment system

    DOEpatents

    Frey, deceased, Gary A.; Jimenez, Oscar D.

    1996-01-01

    A turbine blade having a preestablished rate of thermal expansion is attached to a turbine flange having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the turbine blade. The turbine flange includes a first upstanding flange and a second upstanding flange having a groove formed therebetween. The turbine flange further includes a recess. Each of the first and second upstanding flanges have a plurality of bores therein. A turbine blade has a first member and a second member positioned in one of the groove and the recess. Each of the first member and the second member have a plurality of bores therein. And, a pin is positioned in respective ones of the plurality of bores in the first and second upstanding members and the first and second members and attach the blade to the turbine flange. The pin has a preestablished rate of thermal expansion being substantially equal to the rate of thermal expansion of the blade.

  12. Preliminary Aerodynamic Investigation of Fan Rotor Blade Morphing

    NASA Technical Reports Server (NTRS)

    Tweedt, Daniel L.

    2012-01-01

    Various new technologies currently under development may enable controlled blade shape variability, or so-called blade morphing, to be practically employed in aircraft engine fans and compressors in the foreseeable future. The current study is a relatively brief, preliminary computational fluid dynamics investigation aimed at partially demonstrating and quantifying the aerodynamic potential of fan rotor blade morphing. The investigation is intended to provide information useful for near-term planning, as well as aerodynamic solution data sets that can be subsequently analyzed using advanced acoustic diagnostic tools, for the purpose of making fan noise comparisons. Two existing fan system models serve as baselines for the investigation: the Advanced Ducted Propulsor fan with a design tip speed of 806 ft/sec and a pressure ratio of 1.294, and the Source Diagnostic Test fan with a design tip speed of 1215 ft/sec and a pressure ratio of 1.470. Both are 22-in. sub-scale, low-noise research fan/nacelle models that have undergone extensive experimental testing in the 9- by 15-foot Low Speed Wind Tunnel at the NASA Glenn Research Center. The study, restricted to fan rotor blade morphing only, involves a fairly simple blade morphing technique. Specifically, spanwise-linear variations in rotor blade-section setting angle are applied to alter the blade shape; that is, the blade is linearly retwisted from hub to tip. Aerodynamic performance comparisons are made between morphed-blade and corresponding baseline configurations on the basis of equal fan system thrust, where rotor rotational speed for the morphed-blade fan is varied to change the thrust level for that configuration. The results of the investigation confirm that rotor blade morphing could be a useful technology, with the potential to enable significant improvements in fan aerodynamic performance. Even though the study is very limited in scope and confined to simple geometric perturbations of two existing fan

  13. Turbojet engine blade damping

    NASA Technical Reports Server (NTRS)

    Srinivasan, A. V.; Cutts, D. G.; Sridhar, S.

    1981-01-01

    The potentials of various sources of nonaerodynamic damping in engine blading are evaluated through a combination of advanced analysis and testing. The sources studied include material hysteresis, dry friction at shroud and root disk interfaces as well as at platform type external dampers. A limited seris of tests was conducted to evaluate damping capacities of composite materials (B/AL, B/AL/Ti) and thermal barrier coatings. Further, basic experiments were performed on titanium specimens to establish the characteristics of sliding friction and to determine material damping constants J and n. All the tests were conducted on single blades. Mathematical models were develthe several mechanisms of damping. Procedures to apply this data to predict damping levels in an assembly of blades are developed and discussed.

  14. Stalling of Helicopter Blades

    NASA Technical Reports Server (NTRS)

    Gustafson, F B; Myers, G C , Jr

    1946-01-01

    Theoretical studies have predicted that operation of helicopter rotor beyond certain combinations of thrust, forward speed, and rotational speed might be prevented by rapidly increasing stalling of the retreating blade. The same studies also indicate that the efficiency of the rotor will increase until these limits are reached or closely approached, so that it is desirable to design helicopter rotors for operation close to the limits imposed by blade stalling. Inasmuch as the theoretical predictions of blade stalling involve numerous approximations and assumptions, an experimental investigation was needed to determine whether, in actual practice, the stall did occur and spread as predicted and to establish the amount of stalling that could be present without severe vibration or control difficulties being introduced. This report presents the results of such an investigation.

  15. Blade pressure measurements

    NASA Astrophysics Data System (ADS)

    Chivers, J. W. H.

    Three measurement techniques which enable rotating pressures to be measured during the normal operation of a gas turbine or a component test rig are described. The first technique was developed specifically to provide steady and transient blade surface pressure data to aid both fan flutter research and general fan performance development. This technique involves the insertion of miniature high frequency response pressure transducers into the fan blades of a large civil gas turbine. The other two techniques were developed to measure steady rotating pressures inside and on the surface of engine or rig turbine blades and also rotating pressures in cooling feed systems. These two low frequency response systems are known as the "pressure pineapple' (a name which resulted from the shape of the original prototype) and the rotating scanivalve.

  16. Fluid blade disablement tool

    DOEpatents

    Jakaboski, Juan-Carlos; Hughs, Chance G.; Todd, Steven N.

    2012-01-10

    A fluid blade disablement (FBD) tool that forms both a focused fluid projectile that resembles a blade, which can provide precision penetration of a barrier wall, and a broad fluid projectile that functions substantially like a hammer, which can produce general disruption of structures behind the barrier wall. Embodiments of the FBD tool comprise a container capable of holding fluid, an explosive assembly which is positioned within the container and which comprises an explosive holder and explosive, and a means for detonating. The container has a concavity on the side adjacent to the exposed surface of the explosive. The position of the concavity relative to the explosive and its construction of materials with thicknesses that facilitate inversion and/or rupture of the concavity wall enable the formation of a sharp and coherent blade of fluid advancing ahead of the detonation gases.

  17. Flap/Lag/Torsion Dynamics of a Uniform, Cantilever Rotor Blade in Hover

    NASA Technical Reports Server (NTRS)

    Johnson, W.

    1977-01-01

    The dynamic stability of the flap/lag/torsion motion of a uniform, cantilever rotor blade in hover is calculated. The influence of blade collective pitch, lag frequency, torsional flexibility, structural coupling, and precone angle on the stability is examined. Good agreement is found with the results of an independent analytical investigation.

  18. Computation of the throat area of a turbine blade ring

    NASA Astrophysics Data System (ADS)

    Mamaev, B. I.; Murashko, V. L.

    2016-01-01

    The throat area is a geometric parameter of the blade ring necessary to profile its blades and compute the turbine capacity. As applied to the filament flow model, the area is defined by the involute of the throat solid figure onto the plane formed by the cascade throat located on one of the cylindrical sections of the blade ring and the radius. An equation is derived for computing the area of the involute, which considers the effect of the shape of the ring's tailing outlines and the fillets at the transition from the outlines to the blade feather. Comparison of the area values for several turbines computed by the derived equation and by a more complex method based on a search for the minimum distances from the tailing edge of the blade to the suction surface of the neighboring blade in the channel revealed slight differences. The fluid-dynamic 2D analysis determined the radial boundaries of the filament bands, the parameters of the cascade that lie on a filament's cylindrical surfaces, and the flow velocity normal to the throat section of the filament. The proposed approach to computation of the throat area is common for problems of both designing and analyzing the turbine operation and allows for excluding, in practice, methodological differences in determination of the flow rate and the flow angles at the outlet of the blade ring.

  19. Enhancing wind turbines efficiency with passive reconfiguration of flexible blades

    NASA Astrophysics Data System (ADS)

    Cognet, Vincent P. A.; Thiria, Benjamin; Courrech Du Pont, Sylvain; MSC Team; PMMH Team

    2015-11-01

    Nature provides excellent examples where flexible materials are advantageous in a fluid stream. By folding, leaves decrease the drag caused by air stream; and birds' flapping is much more efficient with flexible wings. Motivated by this, we investigate the effect of flexible blades on the performance of a wind turbine. The effect of chordwise flexible blades is studied both experimentally and theoretically on a small wind turbine in steady state. Four parameters are varied: the wind velocity, the resisting torque, the pitch angle, and the blade's bending modulus. We find an optimum efficiency with respect to the bending modulus. By tuning our four parameters, the wind turbine with flexible blades has a high-efficiency range significantly larger than rigid blades', and, furthermore enhances the operating range. These results are all the more important as one of the current issues concerning wind turbines is the enlargement of their operating range. To explain these results, we propose a simple two-dimensional model by discretising the blade along the radius. We take into account the variation of drag and lift coefficients with the bending ability. This model matches experimental observations and demonstrates the contribution of the reconfiguration of the blade. Matiere et Systemes Complexes.

  20. Aeroelastic tailoring in wind-turbine blade applications

    SciTech Connect

    Veers, P.; Lobitz, D.; Bir, G.

    1998-04-01

    This paper reviews issues related to the use of aeroelastic tailoring as a cost-effective, passive means to shape the power curve and reduce loads. Wind turbine blades bend and twist during operation, effectively altering the angle of attack, which in turn affects loads and energy production. There are blades now in use that have significant aeroelastic couplings, either on purpose or because of flexible and light-weight designs. Since aeroelastic effects are almost unavoidable in flexible blade designs, it may be desirable to tailor these effects to the authors advantage. Efforts have been directed at adding flexible devices to a blade, or blade tip, to passively regulate power (or speed) in high winds. It is also possible to build a small amount of desirable twisting into the load response of a blade with proper asymmetric fiber lay up in the blade skin. (Such coupling is akin to distributed {delta}{sub 3} without mechanical hinges.) The tailored twisting can create an aeroelastic effect that has payoff in either better power production or in vibration alleviation, or both. Several research efforts have addressed different parts of this issue. Research and development in the use of aeroelastic tailoring on helicopter rotors is reviewed. Potential energy gains as a function of twist coupling are reviewed. The effects of such coupling on rotor stability have been studied and are presented here. The ability to design in twist coupling with either stretching or bending loads is examined also.

  1. Containment of composite fan blades

    NASA Technical Reports Server (NTRS)

    Coppa, A. P.; Stotler, C. L.

    1977-01-01

    The development of containment concepts for use with large composite fan blades, taking into account the frangible nature of composite blades is considered. Aspects of the development program include; (1) an analysis to predict the interaction between a failed fan blade and the blade containment structure; (2) scaling factors to allow impact testing using subscale containment rings and simulated blades; (3) the design and fabrication of containment systems for further evaluation in a rotating rig test facility; (4) evaluate the test data against the analytically predicted results; and (5) determine overall systems weights and design characteristics of a composite fan stage installation and compare to the requirements of an equivalent titanium fan blade system. Progress in the blade impact penetration tests and the design and fabrication of blade containment systems is reported.

  2. Surface controlled blade stabilizer

    DOEpatents

    Russell, Larry R.

    1983-01-01

    Drill string stabilizer apparatus, controllable to expand and retract entirely from the surface by control of drill string pressure, wherein increase of drill string pressure from the surface closes a valve to create a piston means which is moved down by drill string pressure to expand the stabilizer blades, said valve being opened and the piston moving upward upon reduction of drill string pressure to retract the stabilizer blades. Upward and downward movements of the piston and an actuator sleeve therebelow are controlled by a barrel cam acting between the housing and the actuator sleeve.

  3. The MOD-1 steel blade

    NASA Technical Reports Server (NTRS)

    Vanbronkhorst, J.

    1979-01-01

    The design, development, fabrication, testing, and transport of two 100 foot metal blades for the MOD-1 WTS are summarized. Because the metal blade design was started late in the MOD-1 system development, many of the design requirements (allocations) were restrictive for the metal blade concept, particularly the maximum weight requirement. The design solutions required to achieve the weight goal resulted in a labor intensive (expensive) fabrication, particularly for a quantity of only two blades manufactured using minimal tooling.

  4. Cooled snubber structure for turbine blades

    DOEpatents

    Mayer, Clinton A; Campbell, Christian X; Whalley, Andrew; Marra, John J

    2014-04-01

    A turbine blade assembly in a turbine engine. The turbine blade assembly includes a turbine blade and a first snubber structure. The turbine blade includes an internal cooling passage containing cooling air. The first snubber structure extends outwardly from a sidewall of the turbine blade and includes a hollow interior portion that receives cooling air from the internal cooling passage of the turbine blade.

  5. Full-field inspection of a wind turbine blade using three-dimensional digital image correlation

    NASA Astrophysics Data System (ADS)

    LeBlanc, Bruce; Niezrecki, Christopher; Avitabile, Peter; Chen, Julie; Sherwood, James; Hughes, Scott

    2011-04-01

    Increasing demand and deployment of wind power has led to a significant increase in the number of wind-turbine blades manufactured globally. As the physical size and number of turbines deployed grows, the probability of manufacturing defects being present in composite turbine blade fleets also increases. As both capital blade costs, and operational and maintenance costs, increase for larger turbine systems the need for large-scale inspection and monitoring of the state of structural health of turbine blades during manufacturing and operation critically increase. One method for locating and quantifying manufacturing defects, while also allowing for the in-situ measurement of the structural health of blades, is through the observation of the full-field state of deformation and strain of the blade. Static tests were performed on a nine-meter CX-100 composite turbine blade to extract full-field displacement and strain measurements using threedimensional digital image correlation (3D DIC). Measurements were taken at several angles near the blade root, including along the high-pressure surface, low-pressure surface, and along the trailing edge of the blade. The overall results indicate that the measurement approach can clearly identify failure locations and discontinuities in the blade curvature under load. Post-processing of the data using a stitching technique enables the shape and curvature of the entire blade to be observed for a large-scale wind turbine blade for the first time. The experiment demonstrates the feasibility of the approach and reveals that the technique readily can be scaled up to accommodate utility-scale blades. As long as a trackable pattern is applied to the surface of the blade, measurements can be made in-situ when a blade is on a manufacturing floor, installed in a test fixture, or installed on a rotating turbine. The results demonstrate the great potential of the optical measurement technique and its capability for use in the wind industry for

  6. Resistive band for turbomachine blade

    SciTech Connect

    Roberts, Herbert Chidsey; Taxacher, Glenn Curtis

    2015-08-25

    A turbomachine system includes a rotor that defines a longitudinal axis of the turbomachine system. A first blade is coupled to the rotor, and the first blade has first and second laminated plies. A first band is coupled to the first blade and is configured to resist separation of the first and second laminated plies.

  7. Angle performance on optima MDxt

    SciTech Connect

    David, Jonathan; Kamenitsa, Dennis

    2012-11-06

    Angle control on medium current implanters is important due to the high angle-sensitivity of typical medium current implants, such as halo implants. On the Optima MDxt, beam-to-wafer angles are controlled in both the horizontal and vertical directions. In the horizontal direction, the beam angle is measured through six narrow slits, and any angle adjustment is made by electrostatically steering the beam, while cross-wafer beam parallelism is adjusted by changing the focus of the electrostatic parallelizing lens (P-lens). In the vertical direction, the beam angle is measured through a high aspect ratio mask, and any angle adjustment is made by slightly tilting the wafer platen prior to implant. A variety of tests were run to measure the accuracy and repeatability of Optima MDxt's angle control. SIMS profiles of a high energy, channeling sensitive condition show both the cross-wafer angle uniformity, along with the small-angle resolution of the system. Angle repeatability was quantified by running a channeling sensitive implant as a regular monitor over a seven month period and measuring the sheet resistance-to-angle sensitivity. Even though crystal cut error was not controlled for in this case, when attributing all Rs variation to angle changes, the overall angle repeatability was measured as 0.16 Degree-Sign (1{sigma}). A separate angle repeatability test involved running a series of V-curves tests over a four month period using low crystal cut wafers selected from the same boule. The results of this test showed the angle repeatability to be <0.1 Degree-Sign (1{sigma}).

  8. Rotor blade system with reduced blade-vortex interaction noise

    NASA Technical Reports Server (NTRS)

    Leishman, John G. (Inventor); Han, Yong Oun (Inventor)

    2005-01-01

    A rotor blade system with reduced blade-vortex interaction noise includes a plurality of tube members embedded in proximity to a tip of each rotor blade. The inlets of the tube members are arrayed at the leading edge of the blade slightly above the chord plane, while the outlets are arrayed at the blade tip face. Such a design rapidly diffuses the vorticity contained within the concentrated tip vortex because of enhanced flow mixing in the inner core, which prevents the development of a laminar core region.

  9. Blade lock for a rotor disk and rotor blade assembly

    NASA Technical Reports Server (NTRS)

    Moore, Jerry H. (Inventor)

    1992-01-01

    A rotor disk 18 and rotor blade 26 assembly is disclosed having a blade lock 66 which retains the rotor blade against axial movement in an axially extending blade retention slot 58. Various construction details are developed which shield the dead rim region D.sub.d and shift at least a portion of the loads associated with the locking device from the dead rim. In one detailed embodiment, a projection 68 from the live rim D.sub.1 of the disk 18 is adapted by slots 86 to receive blade locks 66.

  10. Tip cap for a turbine rotor blade

    SciTech Connect

    Kimmel, Keith D

    2014-03-25

    A turbine rotor blade with a spar and shell construction, and a tip cap that includes a row of lugs extending from a bottom side that form dovetail grooves that engage with similar shaped lugs and grooves on a tip end of the spar to secure the tip cap to the spar against radial displacement. The lug on the trailing edge end of the tip cap is aligned perpendicular to a chordwise line of the blade in the trailing edge region in order to minimize stress due to the lugs wanting to bend under high centrifugal loads. A two piece tip cap with lugs at different angles will reduce the bending stress even more.

  11. Efficiency improvement of a new vertical axis wind turbine by individual active control of blade motion

    NASA Astrophysics Data System (ADS)

    Hwang, In Seong; Min, Seung Yong; Jeong, In Oh; Lee, Yun Han; Kim, Seung Jo

    2006-03-01

    In this paper, a research for the performance improvement of the straight-bladed vertical axis wind turbine is described. To improve the performance of the power generation system, which consists of several blades rotating about axis in parallel direction, the cycloidal blade system and the individual active blade control system are adopted, respectively. Both methods are variable pitch system. For cycloidal wind turbine, aerodynamic analysis is carried out by changing pitch angle and phase angle based on the cycloidal motion according to the change of wind speed and wind direction, and control mechanism using the cycloidal blade system is realized for 1kw class wind turbine. By this method, electrical power is generated about 30% higher than wind turbine using fixed pitch angle method. And for more efficient wind turbine, individual pitch angle control of each blade is studied. By maximizing the tangential force in each rotating blade at the specific rotating position, optimal pitch angle variation is obtained. And several airfoil shapes of NACA 4-digit and NACA 6-series are studied. Aerodynamic analysis shows performance improvement of 60%. To realize this motion, sensing and actuating system is designed.

  12. Incidence loss for fan turbine rotor blade in two-dimensional cascade

    NASA Technical Reports Server (NTRS)

    Kline, J. F.; Moffitt, T. P.; Stabe, R. G.

    1983-01-01

    The effect of incidence angle on the aerodynamic performance of a fan turbine rotor blade was investigated experimentally in a two dimensional cascade. The test covered a range of incidence angles from -15 deg to 10 deg and exit ideal critical velocity ratios from 0.75 to 0.95. The principal measurements were blade-surface static pressures and cross-channel survey of exit total pressure, static pressure, and flow angle. Flow adjacent to surfaces was examined using a visualization technique. The results of the investigation include blade-surface velocity distribution and overall kinetic energy loss coefficients for the incidence angles and exit velocity ratios tested. The measured losses are compared with those from a reference core turbine rotor blade and also with two common analytical methods of predicting incidence loss.

  13. Razor Blades to Computers.

    ERIC Educational Resources Information Center

    Schneider, Arthur

    Stages in developing editing equipment and processes for videotape are described. In 1956, when the first broadcast videotape recorders were installed, a splicing block, consisting of an aluminum block, steel ruler, and sharp razor blade, was used. Gradually, technicians developed more sophisticated methods. At present, two very advanced methods…

  14. Boundary Layer Transition Detection on a Rotor Blade Using Rotating Mirror Thermography

    NASA Technical Reports Server (NTRS)

    Heineck, James T.; Schuelein, Erich; Raffel, Markus

    2014-01-01

    Laminar-to-turbulent transition on a rotor blade in hover has been imaged using an area-scan infrared camera. A new method for tracking a blade using a rotating mirror was employed. The mirror axis of rotation roughly corresponded to the rotor axis of rotation and the mirror rotational frequency is 1/2 that of the rotor. This permitted the use of cameras whose integration time was too long to prevent image blur due to the motion of the blade. This article will show the use of this method for a rotor blade at different collective pitch angles.

  15. What's Your Angle on Angles?

    ERIC Educational Resources Information Center

    Browning, Christine A.; Garza-Kling, Gina; Sundling, Elizabeth Hill

    2007-01-01

    Although the nature of the research varies, as do concepts of angle, research in general supports the supposition that angle is a complex idea, best understood from a variety of perspectives. In fact, the concept of angle tends to be threefold, consisting of: (1) the traditional, static notion of two rays meeting at a common vertex; (2) the idea…

  16. Induced strain actuation of composite beams and rotor blades with embedded piezoceramic elements

    NASA Astrophysics Data System (ADS)

    Chen, Peter C.; Chopra, Inderjit

    1994-05-01

    The objective of this research is to develop a dynamically scaled (Froude scale) helicopter rotor blade with embedded piezoceramic elements as sensors and actuators to control blade vibrations. A 6-ft-diameter two-bladed bearingless rotor model was built, where each blade is embedded with banks of piezoelectric actuators at +/- 45-degree angles with respect to the beam axis on the top and bottom surfaces. A twist distribution along the blade span is achieved through in-phase excitation of the top and bottom actuators at equal potentials, while a bending distribution is achieved through out-of-phase excitation. In order to fix design variables and to optimize blade performance, a uniform strain beam theory is formulated to analytically predict the static bending and torsional response of composite rectangular beams with embedded piezoelectric actuators. Parameters such as bond thicknesses, actuator skew angle, and actuator spacing are investigated by experiments and then validated by theory. The static bending and torsional response of the rotor blades is experimentally measured and correlated with theory. Dynamic torsional and bending responses are experimentally determined for frequencies from 2-120 HZ to assess the viability of a vibration reduction system based on piezoactuation of blade twist. Although the magnitudes of blade twist attained in this experiment were small, it is expected that future models can be built with improved performance.

  17. Rotor blade vortex interaction noise

    NASA Astrophysics Data System (ADS)

    Yu, Yung H.

    2000-02-01

    Blade-vortex interaction noise-generated by helicopter main rotor blades is one of the most severe noise problems and is very important both in military applications and community acceptance of rotorcraft. Research over the decades has substantially improved physical understanding of noise-generating mechanisms, and various design concepts have been investigated to control noise radiation using advanced blade planform shapes and active blade control techniques. The important parameters to control rotor blade-vortex interaction noise and vibration have been identified: blade tip vortex structures and its trajectory, blade aeroelastic deformation, and airloads. Several blade tip design concepts have been investigated for diffusing tip vortices and also for reducing noise. However, these tip shapes have not been able to substantially reduce blade-vortex interaction noise without degradation of rotor performance. Meanwhile, blade root control techniques, such as higher-harmonic pitch control (HHC) and individual blade control (IBC) concepts, have been extensively investigated for noise and vibration reduction. The HHC technique has proved the substantial blade-vortex interaction noise reduction, up to 6 dB, while vibration and low-frequency noise have been increased. Tests with IBC techniques have shown the simultaneous reduction of rotor noise and vibratory loads with 2/rev pitch control inputs. Recently, active blade control concepts with smart structures have been investigated with the emphasis on active blade twist and trailing edge flap. Smart structures technologies are very promising, but further advancements are needed to meet all the requirements of rotorcraft applications in frequency, force, and displacement.

  18. A study of casing treatment stall margin improvement phenomena. [for axial compressor rotor blade tips

    NASA Technical Reports Server (NTRS)

    Prince, D. C., Jr.; Wisler, D. C.; Hilvers, D. E.

    1975-01-01

    The results of a program of experimental and analytical research in casing treatments over axial compressor rotor blade tips are presented. Circumferential groove, axial-skewed slot and blade angle slot treatments were tested at low speeds. With the circumferential groove treatment the stalling flow was reduced 5.8% at negligible efficiency sacrifice. The axial-skewed slot treatment improved the stalling flow by 15.3%; 1.8 points in peak efficiency were sacrificed. The blade angle slot treatment improved the stalling flow by 15.0%; 1.4 points in peak efficiency were sacrificed. The favorable stalling flow situations correlated well with observations of higher-than-normal surface pressures on the rotor blade pressure surfaces in the tip region, and with increased maximum diffusions on the suction surfaces. Annulus wall pressure gradients, especially in the 50 to 75% chord region, are also increased and blade surface pressure loadings are shifted toward the trailing edge for treated configurations.

  19. Fan Stagger Angle for Dirt Rejection

    NASA Technical Reports Server (NTRS)

    Gallagher, Edward J. (Inventor); Rose, Becky E. (Inventor); Brilliant, Lisa I. (Inventor)

    2015-01-01

    A gas turbine engine includes a spool, a turbine coupled to drive the spool, a propulsor coupled to be rotated about an axis by the turbine through the spool, and a gear assembly coupled between the propulsor and the spool such that rotation of the turbine drives the propulsor at a different speed than the spool. The propulsor includes a hub and a row of propulsor blades that extend from the hub. Each of the propulsor blades has a span between a root at the hub and a tip, and a chord between a leading edge and a trailing edge. The chord forms a stagger angle alpha with the axis, and the stagger angle alpha is less than 15 deg. at a position along the propulsor blade that is within an inboard 20% of the span.

  20. Unsteady flow field in a mini VAWT with relative rotation blades: analysis of temporal results

    NASA Astrophysics Data System (ADS)

    Bayeul-Lainé, A. C.; Simonet, S.; Bois, G.

    2013-12-01

    The present wind turbine is a small one which can be used on roofs or in gardens. This turbine has a vertical axis. Each turbine blade combines a rotating movement around its own axis and around the main rotor axis. Due to this combination of movements, flow around this turbine is highly unsteady and needs to be modelled by unsteady calculation. The present work is an extended study starting in 2009. The benefits of combined rotating blades have been shown. The performance coefficient of this kind of turbine is very good for some blade stagger angles. Spectral analysis of unsteady results on specific points in the domain and temporal forces on blades was already presented for elliptic blades. The main aim here is to compare two kinds of blades in case of the best performances.

  1. Design of blade-shaped-electrode linear ion traps with reduced anharmonic contributions

    SciTech Connect

    Deng, K.; Che, H.; Ge, Y. P.; Xu, Z. T.; Yuan, W. H.; Zhang, J.; Lu, Z. H.; Lan, Y.

    2015-09-21

    RF quadrupole linear Paul traps are versatile tools in quantum physics experiments. Linear Paul traps with blade-shaped electrodes have the advantages of larger solid angles for fluorescence collection. But with these kinds of traps, the existence of higher-order anharmonic terms of the trap potentials can cause large heating rate for the trapped ions. In this paper, we theoretically investigate the dependence of higher-order terms of trap potentials on the geometry of blade-shaped traps, and offer an optimized design. A modified blade electrodes trap is proposed to further reduce higher-order anharmonic terms while still retaining large fluorescence collection angle.

  2. Performance and internal flow condition of mini centrifugal pump with splitter blades

    NASA Astrophysics Data System (ADS)

    Shigemitsu, T.; Fukutomi, J.; Kaji, K.; Wada, T.

    2012-11-01

    Mini centrifugal pumps having a diameter smaller than 100mm are employed in many fields. But the design method for the mini centrifugal pump is not established because the internal flow condition for these small-sized fluid machines is not clarified and conventional theory is not suitable for small-sized pumps. Therefore, mini centrifugal pumps with simple structure were investigated by this research. Splitter blades were adopted in this research to improve the performance and the internal flow condition of mini centrifugal pump which had large blade outlet angle. The original impeller without the splitter blades and the impeller with the splitter blades were prepared for an experiment. The performance tests are conducted with these rotors in order to investigate the effect of the splitter blades on performance and internal flow condition of mini centrifugal pump. On the other hand, a three dimensional steady numerical flow analysis is conducted with the commercial code (ANSYS-CFX) to investigate the internal flow condition in detail. It is clarified from the experimental results that the performance of the mini centrifugal pump is improved by the effect of the splitter blades. The blade-to-blade low velocity regions are suppressed in the case with the splitter blades and the total pressure loss regions are decreased. The effects of the splitter blades on the performance and the internal flow condition are discussed in this paper.

  3. Overview on the profile measurement of turbine blade and its development

    NASA Astrophysics Data System (ADS)

    Huang, Junhui; Wang, Zhao; Gao, Jianmin; Yu, Yanguang

    2010-10-01

    Turbine machinery has an extraordinary wide range of applications in the aviation, aerospace, automotive, energy and many other industries. The turbine blade is one of the most important parts of turbine machinery, and the characteristic parameters, pressure ratio of the engine and rotating speed of the turbine are all related to the shape and size of blades. Therefore, the profile measurement of turbine blade is an essential issue in the blade machining processing, however, it is difficult and particular to establish the profile measurement of turbine blade because of its complicated shapes and space angles of the blades, and the specific stringent environmental requirements need a more appropriate measurement method to the Turbine Blade profile measurement. This paper reviews the recent research and development on the Turbine Blade profile measurement methods, which mainly describes several common and advanced measurement methods, such as the traditional coordinate measuring machines, some optical measurement methods with the characteristics of non-contact like optical theodolite, three-dimensional photography, laser interferometry, as well as the laser triangulation method studied more recently and so on. Firstly, the measuring principles, the key technical issues and the applications in the Turbine Blade profile measurement of the methods which are mentioned above are described respectively in detail, and the characteristics of those methods are analyzed in this paper. Furthermore, the scope of application and limitations of those measurement methods are summed up. Finally, some views on the current research focus and perspective trend of the Turbine Blade profile measurement technology are presented.

  4. Graphene in turbine blades

    NASA Astrophysics Data System (ADS)

    Das, D. K.; Swain, P. K.; Sahoo, S.

    2016-07-01

    Graphene, the two-dimensional (2D) nanomaterial, draws interest of several researchers due to its many superior properties. It has extensive applications in numerous fields. A turbine is a hydraulic machine which extracts energy from a fluid and converts it into useful work. Recently, Gudukeya and Madanhire have tried to increase the efficiency of Pelton turbine. Beucher et al. have also tried the same by reducing friction between fluid and turbine blades. In this paper, we study the advantages of using graphene as a coating on Pelton turbine blades. It is found that the efficiency of turbines increases, running and maintenance cost is reduced with more power output. By the application of graphene in pipes, cavitation will be reduced, durability of pipes will increase, operation and maintenance cost of water power plants will be less.

  5. Constructal blade shape in nanofluids

    PubMed Central

    2011-01-01

    Blade configuration of nanofluids has been proven to perform much better than dispersed configuration for some heat conduction systems. The analytical analysis and numerical calculation are made for the cylinder--shaped and regular-rectangular-prism--shaped building blocks of the blade-configured heat conduction systems (using nanofluids as the heat conduction media) to find the optimal cross-sectional shape for the nanoparticle blade under the same composing materials, composition ratio, volumetric heat generation rate, and total building block volume. The regular-triangular-prism--shaped blade has been proven to perform better than all the other three kinds of blades, namely, the regular-rectangular-prism--shaped blade, the regular-hexagonal-prism--shaped blade, and the cylinder--shaped blade. Thus, the regular-triangular-prism--shaped blade is selected as the optimally shaped blade for the two kinds of building blocks that are considered in this study. It is also proven that the constructal cylinder--regular-triangular-prism building block performs better than the constructal regular-rectangular-prism--regular-triangular-prism building block. PMID:21711751

  6. Performance predictions of VAWTs with NLF airfoil blades

    SciTech Connect

    Masson, C.; Leclerc, C.; Paraschivoiu, I.

    1997-02-01

    The successful design of an efficient Vertical Axis Wind Turbine (VAWT) can be obtained only when appropriate airfoil sections have been selected. Most VAWTs currently operating worldwide use blades of symmetrical NACA airfoil series. As these blades were designed for aviation applications, Sandia National Laboratories developed a family of airfoils specifically designed for VAWTs in order to decrease the Cost of Energy (COE) of the VAWT (Berg, 1990). Objectives formulated for the blade profile were: modest values of maximum lift coefficient, low drag at low angle of attack, high drag at high angle of attack, sharp stall, and low thickness-to-chord ratio. These features are similar to those of Natural Laminar Flow airfoils (NLF) and gave birth to the SNLA airfoil series. This technical brief illustrates the benefits and losses resulting from using NLF airfoils on VAWT blades. To achieve this goal, the streamtube model of Paraschivoiu (1988) is used to predict the performance of VAWTs equipped with blades of various airfoil shapes. The airfoil shapes considered are the conventional airfoils NACA 0018 and NACA 0021, and the SNLA 0018/50 airfoil designed at Sandia. Furthermore, the potential benefit of reducing the airfoil drag is clearly illustrated by the presentation of the individual contributions of lift and drag to power.

  7. Performance analysis of mini centrifugal pump with splitter blades

    NASA Astrophysics Data System (ADS)

    Shigemitsu, T.; Fukutomi, J.; Wada, T.; Shinohara, H.

    2013-12-01

    Design method for a mini centrifugal pump is not established because the internal flow condition for these small-sized fluid machines is not clarified and conventional theory is not suitable for small-sized pumps. Then, a semi-open impeller for the mini centrifugal pump with 55mm impeller diameter is adopted in this research to take simplicity and maintenance into consideration. Splitter blades are adopted in this research to improve the performance and internal flow condition of mini centrifugal pump having large blade outlet angle. The performance tests are conducted with these rotors in order to investigate the effect of the splitter blades on the performance and internal flow condition of the mini centrifugal pump. A three dimensional steady numerical flow analysis is conducted to analyze rotor, volute efficiency and loss caused by a vortex. It is clarified from the experimental results that the performance of the mini centrifugal pump is improved by the effect of the splitter blades. Flow condition at outlet of the rotor becomes uniform and back flow regions are suppressed in the case with the splitter blades. Further, the volute efficiency increases and the vortex loss decreases. In the present paper, the performance of the mini centrifugal pump is shown and the flow condition is clarified with the results of the experiment and the numerical flow analysis. Furthermore, the performance analyses of the mini centrifugal pumps with and without the splitter blades are conducted.

  8. PMR polyimide/graphite fiber composite fan blades

    NASA Technical Reports Server (NTRS)

    Cavano, P. J.; Winters, W. E.

    1976-01-01

    Ultrahigh speed fan blades, designed in accordance with the requirements of an ultrahigh tip speed blade axial flow compressor, were fabricated from a high strength graphite fiber tow and a PMR polyimide resin. The PMR matrix was prepared by combining three monomeric reactants in methyl alcohol, and the solution was applied directly to the reinforcing fiber for subsequent in situ polymerization. Some of the molded blades were completely finished by secondary bonding of root pressure pads and an electroformed nickel leading edge sheath prior to final machining. The results of the spin testing of nine PMR fan blades are given. Prior to blade fabrication, heat resin tensile properties of the PMR resin were examined at four formulated molecular weight levels. Additionally, three formulated molecular weight levels were investigated in composite form with both a high modulus and a high strength fiber, both as-molded and postcured, in room temperature and 232 C transverse tensile, flexure and short beam shear. Mixed fiber orientation panels simulating potential blade constructions were also evaluated. Flexure tests, short beam shear tests, and tensile tests were conducted on these angle-plied laminates.

  9. Blade Vibration Measurement System

    NASA Technical Reports Server (NTRS)

    Platt, Michael J.

    2014-01-01

    The Phase I project successfully demonstrated that an advanced noncontacting stress measurement system (NSMS) could improve classification of blade vibration response in terms of mistuning and closely spaced modes. The Phase II work confirmed the microwave sensor design process, modified the sensor so it is compatible as an upgrade to existing NSMS, and improved and finalized the NSMS software. The result will be stand-alone radar/tip timing radar signal conditioning for current conventional NSMS users (as an upgrade) and new users. The hybrid system will use frequency data and relative mode vibration levels from the radar sensor to provide substantially superior capabilities over current blade-vibration measurement technology. This frequency data, coupled with a reduced number of tip timing probes, will result in a system capable of detecting complex blade vibrations that would confound traditional NSMS systems. The hardware and software package was validated on a compressor rig at Mechanical Solutions, Inc. (MSI). Finally, the hybrid radar/tip timing NSMS software package and associated sensor hardware will be installed for use in the NASA Glenn spin pit test facility.

  10. Blade-Pitch Control for Quieting Tilt-Rotor Aircraft

    NASA Technical Reports Server (NTRS)

    Betzina, Mark D.; Nguyen, Khanh Q.

    2004-01-01

    A method of reducing the noise generated by a tilt-rotor aircraft during descent involves active control of the blade pitch of the rotors. This method is related to prior such noise-reduction methods, of a type denoted generally as higher-harmonic control (HHC), in which the blade pitch is made to oscillate at a harmonic of the frequency of rotation of the rotor. A tilt-rotor aircraft is so named because mounted at its wing tips are motors that can be pivoted to enable the aircraft to take off and land like a helicopter or to fly like a propeller airplane. When the aircraft is operating in its helicopter mode, the rotors generate more thrust per unit rotor-disk area than helicopter rotors do, thus producing more blade-vortex interaction (BVI) noise. BVI is a major source of noise produced by helicopters and tilt-rotor aircraft during descent: When a rotor descends into its own wake, the interaction of each blade with the blade-tip vortices generated previously gives rise to large air-pressure fluctuations. These pressure fluctuations radiate as distinct, impulsive noise. In general, the pitch angle of the rotor blades of a tilt-rotor aircraft is controlled by use of a swash plate connected to the rotor blades by pitch links. In both prior HHC methods and the present method, HHC control signals are fed as input to swash-plate control actuators, causing the rotor-blade pitch to oscillate. The amplitude, frequency, and phase of the control signal can be chosen to minimize BVI noise.

  11. Snubber assembly for turbine blades

    DOEpatents

    Marra, John J

    2013-09-03

    A snubber associated with a rotatable turbine blade in a turbine engine, the turbine blade including a pressure sidewall and a suction sidewall opposed from the pressure wall. The snubber assembly includes a first snubber structure associated with the pressure sidewall of the turbine blade, a second snubber structure associated with the suction sidewall of the turbine blade, and a support structure. The support structure extends through the blade and is rigidly coupled at a first end portion thereof to the first snubber structure and at a second end portion thereof to the second snubber structure. Centrifugal loads exerted by the first and second snubber structures caused by rotation thereof during operation of the engine are at least partially transferred to the support structure, such that centrifugal loads exerted on the pressure and suctions sidewalls of the turbine blade by the first and second snubber structures are reduced.

  12. Experimental investigation of an 0.8 hub-tip radius-ratio,nontwisted-rotor-blade turbine

    NASA Technical Reports Server (NTRS)

    Silvern, David H; Slivka, William R

    1951-01-01

    An experimental investigation of a 0.8 hub-tip radius ratio, nontwisted-rotor-blade turbine designed for a stagnation-pressure ratio of 2.5 and an equivalent mean blade speed of 643 feet per second was made in a cold-air turbine with (a) nontwisted stator blades, and (b) twisted stator blades designed to maintain zero rotor-inlet incidence angles. Turbine efficiencies of the order of 0.85 at the design point were obtained with a nontwisted-rotor-blade turbine with a hub-tip radius ratio of 0.80. The turbine with the twisted stator blades gave higher efficiencies at the design point (of the order of 1.5 percentage points) than the turbine with the nontwisted stator blades.

  13. Computer program for definition of transonic axial-flow compressor blade rows. [computer program for fabrication and aeroelastic analysis

    NASA Technical Reports Server (NTRS)

    Crouse, J. E.

    1974-01-01

    A method is presented for designing axial-flow compressor blading from blade elements defined on cones which pass through the blade-edge streamline locations. Each blade-element centerline is composed of two segments which are tangent to each other. The centerline and surfaces of each segment have constant change of angle with path distance. The stacking line for the blade elements can be leaned in both the axial and tangential directions. The output of the computer program gives coordinates for fabrication and properties for aeroelastic analysis for planar blade sections. These coordinates and properties are obtained by interpolation across conical blade elements. The program is structured to be coupled with an aerodynamic design program.

  14. Savonius rotor using swinging blades as an augmentation system

    NASA Astrophysics Data System (ADS)

    Aldos, T. K.

    The power output from a Savonius rotor can be improved by reducing the drag force on the up-wind blades. A new method of doing this is experimentally investigated in the present work. The method depends on allowing the rotor blades to swing back when they are on the upwind stroke. A high and real power augmentation may be achieved by the new system at an optimum angle of swing. The system is independent of wind direction, is simple to construct, and requires no additional accessories.

  15. Stacking optimization of compressor blades of gas turbine engines

    NASA Technical Reports Server (NTRS)

    Cheu, Tsu-Chien

    1990-01-01

    A procedure is presented to obtain optimal designs of axial compressor blades with structural design constraints. Coefficients of the polynomials defining the circumferential tilting angles and the axial leaning distances of the airfoil cross sections from the initial design geometry are used as design variables. The compressor blades are modeled by 20-node solid elements. An efficient finite element method is developed for modal analysis and sensitivity analysis with respect to the design variables. Based on this information, a sequential linear programming method is applied to calculate the required change of geometry for the desired structural design constraints.

  16. Dynamic analysis of rotor blade undergoing rotor power shutdown

    NASA Technical Reports Server (NTRS)

    Nguyen, Khanh Quoc

    1990-01-01

    A rigid flap-lag blade analysis was developed to simulate a rotor in a wind tunnel undergoing an emergency power shutdown. Results show that for a rotor at a nonzero shaft tilt angle undergoing an emergency power shutdown, the oscillatory lag response is divergent. The mean lag response is large when tested at high collective pitch angles. Reducing the collective pitch during the emergency shutdown reduces the steady lag response. Increasing the rotor shaft tilt angle increases the oscillatory lag response component. The blade lag response obtained by incorporating a nonlinear lag damper model indicates that in this case the equivalent linear viscous damping is lower than originally expected. Simulation results indicate that large oscillatory lag motions can be suppressed if the rotor shaft is returned to the fully vertical position during the emergency power shutdown.

  17. Aerodynamic Measurements of an Incidence Tolerant Blade in a Transonic Turbine Cascade

    NASA Technical Reports Server (NTRS)

    McVetta, Ashlie B.; Giel, Paul W.

    2012-01-01

    An overview of the recent facility modifications to NASA s Transonic Turbine Blade Cascade Facility and aerodynamic measurements on the VSPT incidence-tolerant blade are presented. This work supports the development of variable-speed power turbine (VSPT) speed-change technology for the NASA Large Civil Tilt Rotor (LCTR) vehicle. In order to maintain acceptable main rotor propulsive efficiency, the VSPT operates over a nearly 50% speed range from takeoff to altitude cruise. This results in 50 or more variations in VSPT blade incidence angles. The Transonic Turbine Blade Cascade Facility has the ability to operate over a wide range of Reynolds numbers and Mach numbers, but had to be modified in order to accommodate the negative incidence angle variation required by the LCTR VSPT operation. Details of the modifications are described. An incidence-tolerant blade was developed under an RTPAS study contract and tested in the cascade to look at the effects of large incidence angle and Reynolds number variations. Recent test results are presented which include midspan exit total pressure and flow angle measurements obtained at three inlet angles representing the cruise, take-off, and maximum incidence flight mission points. For each inlet angle, data were obtained at five flow conditions with exit Reynolds numbers varying from 2.12 106 to 2.12 105 and two isentropic exit Mach numbers of 0.72 and 0.35. Three-dimensional flowfield measurements were also acquired at the cruise and take-off points. The flowfield measurements were acquired using a five-hole and three-hole pneumatic probe located in a survey plane 8.6% axial chord downstream of the blade trailing edge plane and covering three blade passages. Blade and endwall static pressure distributions were also acquired for each flow condition.

  18. Ceramic blade with tip seal

    DOEpatents

    Glezer, B.; Bhardwaj, N.K.; Jones, R.B.

    1997-08-05

    The present gas turbine engine includes a disc assembly defining a disc having a plurality of blades attached thereto. The disc has a preestablished rate of thermal expansion and the plurality of blades have a preestablished rate of thermal expansion being less than the preestablished rate of thermal expansion of the disc. A shroud assembly is attached to the gas turbine engine and is spaced from the plurality of blades a preestablished distance forming an interface there between. Positioned in the interface is a seal having a preestablished rate of thermal expansion being generally equal to the rate of thermal expansion of the plurality of blades. 4 figs.

  19. Superhybrid composite blade impact studies

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Lark, R. F.; Sinclair, J. H.

    1980-01-01

    The feasibility of superhybrid composite blades for meeting the mechanical design and impact resistance requirements of large fan blades for aircraft turbine engine applications was investigated. Two design concepts were evaluated: leading edge spar (TiCom) and center spar (TiCore), both with superhybrid composite shells. The investigation was both analytical and experimental. The results obtained show promise that superhybrid composites can be used to make light weight, high quality, large fan blades with good structural integrity. The blades tested successfully demonstrated their ability to meet steady state operating conditions, overspeed, and small bird impact requirements.

  20. Superhybrid composite blade impact studies

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Lark, R. F.; Sinclair, J. H.

    1981-01-01

    An investigation was conducted to determine the feasibility of superhybrid composite blades for meeting the mechanical design and impact resistance requirements of large fan blades for aircraft turbine engine applications. Two design concepts were evaluated: (1) leading edge spar (TiCom) and (2) center spar (TiCore), both with superhybrid composite shells. The investigation was both analytical and experimental. The results obtained show promise that superhybrid composites can be used to make light-weight, high-quality, large fan blades with good structural integrity. The blades tested successfully demonstrated their ability to meet steady-state operating conditions, overspeed, and small bird impact requirements.

  1. Comparison of NACA 65-series compressor-blade pressure distributions and performance in a rotor and in cascade

    NASA Technical Reports Server (NTRS)

    Westphal, Willard R; Godwin, William R

    1957-01-01

    An investigation has been conducted to compare the performance of NACA 65-series compressor blades in two-dimensional cascade with that in an axial flow compressor. Blade pressure distributions were obtained by the use of a mercury-seal pressure-transfer device. The comparison indicated that cascade data accurately predicted the turning angle and blade pressure distribution obtained in the compressor at design conditions.

  2. Dynamics of an experimental two bladed horizontal axis wind turbine with blade cyclic pitch variation

    NASA Technical Reports Server (NTRS)

    Hotenemser, K. H.; Swift, A. H. P.

    1981-01-01

    The turbine under study incorporates the combination of two features: the application of blade cyclic pitch variation; and the use of yaw angle control for rotor speed and torque regulation. Due to its emasculation by passive cyclic pitch variation the rotor can be rapidly yawed without encountering gyroscopic and aerodynamic hub moments and without noticeable out of plane excursions. The two bladed upwind rotor is vane stabilized and of very simple and rugged design. The principle was first checked out with a small scale wind tunnel model and then tested in the atmosphere with a 7.6 meter diameter experimental fully instrumented wind turbine driving a 3 phase alternator. The test results are summarized with respect to structural dynamics and yaw dynamics.

  3. Helicopter rotor blade design for minimum vibration

    NASA Technical Reports Server (NTRS)

    Taylor, R. B.

    1984-01-01

    The importance of blade design parameters in rotor vibratory response and the design of a minimum vibration blade based upon this understanding are examined. Various design approaches are examined for a 4 bladed articulated rotor operating at a high speed flight condition. Blade modal shaping, frequency placement, structural and aerodynamic coupling, and intermodal cancellation are investigated to systematically identify and evaluate blade design parameters that influence blade airloads, blade modal response, hub loads, and fuselage vibration. The relative contributions of the various components of blade force excitation and response to the vibratory hub loads transmitted to the fuselage are determined in order to isolate primary candidates for vibration alleviation. A blade design is achieved which reduces the predicted fuselage vibration from the baseline blade by approximately one half. Blade designs are developed that offer significant reductions in vibration (and fatigue stresses) without resorting to special vibration alleviation devices, radical blade geometries, or weight penalties.

  4. Effect of blade loading and rotor speed on the optimal aerodynamic performance of wind turbine blades

    NASA Astrophysics Data System (ADS)

    Bryson, Christopher; Hussain, Fazle; Barhorst, Alan

    2015-11-01

    Optimization of wind turbine torque as a function of angle of attack - over the entire speed range from start-up to cut-off - is studied by considering the full trigonometric relations projecting lift and drag to thrust and torque. Since driving force and thrust are geometrically constrained, one cannot be changed without affecting the other. Increasing lift to enhance torque simultaneously increases thrust, which subsequently reduces the inflow angle with respect to the rotor plane via an increased reduction in inflow velocity. Reducing the inflow angle redirects the lift force away from the driving force generating the torque, which may reduce overall torque. Similarly, changes in the tip-speed ratio (TSR) affect the inflow angle and thus the optimal torque. Using the airfoil data from the NREL 5 MW reference turbine, the optimal angle of attack over the operational TSR range (4 to 15) was computed using a BEM model to incorporate the dynamic coupling, namely the interdependency of blade loading and inflow angle. The optimal angle of attack is close to minimum drag during start-up phase (high TSR) and continuously increases toward maximum lift at high wind speeds (low TSR).

  5. Effect of angle of attack on rotor trailing-edge noise

    NASA Astrophysics Data System (ADS)

    Chou, S.-T.; George, A. R.

    1984-12-01

    Previous analyses of boundary layer trailing edge noise for large rotors have used zero blade angle of attack as input data. Attention is presently given to the important effects of blade angle of attack changes on rotor trailing edge noise in the case of a UH-1 helicopter. The primary effect is in the low to mid-frequency range, where noise level increases with angle of attack.

  6. Estimation of blade airloads from rotor blade bending moments

    NASA Technical Reports Server (NTRS)

    Bousman, William G.

    1987-01-01

    A method is developed to estimate the blade normal airloads by using measured flap bending moments; that is, the rotor blade is used as a force balance. The blade's rotation is calculated in vacuum modes and the airloads are then expressed as an algebraic sum of the mode shapes, modal amplitudes, mass distribution, and frequency properties. The modal amplitudes are identified from the blade bending moments using the Strain Pattern Analysis Method. The application of the method is examined using simulated flap bending moment data that have been calculated for measured airloads for a full-scale rotor in a wind tunnel. The estimated airloads are compared with the wind tunnel measurements. The effects of the number of measurements, the number of modes, and errors in the measurements and the blade properties are examined, and the method is shown to be robust.

  7. Low-speed cascade investigation of loaded leading-edge compressor blades

    NASA Technical Reports Server (NTRS)

    Emery, James C

    1956-01-01

    Six percent thick NACA 63-series compressor-blade sections having a loaded leading-edge A4K6 mean line have been investigated systematically in a two-dimensional porous-wall cascade over a range of Reynolds numbers from 160,000 to 385,000. Blades cambered to have isolated-airfoil lift coefficients of 0.6, 1.2, 1.8, and 2.4 were tested over the usable angle-of-attack range at inlet-air angles of 30 degrees, 45 degrees, and 60 degrees and solidities of 1.0 and 1.5. A comparison with data of NACA RM L51G31, shows that the angle-of-attack operating range is 2 degrees to 4 degrees less than the range for the uniformly loaded section; however, the wake losses near design angle of attack are slightly lower than those for the uniformly loaded section. Except for highly cambered blades at high inlet angles, the 63-(C s oA4K6)06 compressor-blade sections are capable of more efficient operation for moderate-speed subsonic compressors at design angle of attack than are the 65-(C s oa10)10 or the 65-(c s oA2I8b)10 compressor-blade sections. In contrast to the other sections, the loaded leading-edge sections are capable of operating efficiently at the lower Reynolds numbers.

  8. Lift capability prediction for helicopter rotor blade-numerical evaluation

    NASA Astrophysics Data System (ADS)

    Rotaru, Constantin; Cîrciu, Ionicǎ; Luculescu, Doru

    2016-06-01

    The main objective of this paper is to describe the key physical features for modelling the unsteady aerodynamic effects found on helicopter rotor blade operating under nominally attached flow conditions away from stall. The unsteady effects were considered as phase differences between the forcing function and the aerodynamic response, being functions of the reduced frequency, the Mach number and the mode forcing. For a helicopter rotor, the reduced frequency at any blade element can't be exactly calculated but a first order approximation for the reduced frequency gives useful information about the degree of unsteadiness. The sources of unsteady effects were decomposed into perturbations to the local angle of attack and velocity field. The numerical calculus and graphics were made in FLUENT and MAPLE soft environments. This mathematical model is applicable for aerodynamic design of wind turbine rotor blades, hybrid energy systems optimization and aeroelastic analysis.

  9. MEMS inertial sensors for load monitoring of wind turbine blades

    NASA Astrophysics Data System (ADS)

    Cooperman, Aubryn M.; Martinez, Marcias J.

    2015-03-01

    Structural load monitoring of wind turbines is becoming increasingly important due increasing turbine size and offshore deployment. Rotor blades are key components that can be monitored by continuously measuring their deflection and thereby determining strain and loads on the blades. In this paper, a method is investigated for monitoring blade deformation that utilizes micro-electromechanical systems (MEMS) comprising triaxial accelerometers, magnetometers and gyroscopes. This approach is demonstrated using a cantilever beam instrumented with 5 MEMS and 4 strain gauges. The measured changes in angles obtained from the MEMS are used to determine a deformation surface which is used as an input to a finite element model in order to estimate the strain throughout the beam. The results are then verified by comparison with strain gauge measurements.

  10. Adjustment disorder

    MedlinePlus

    American Psychiatric Association. Diagnostic and statistical manual of mental disorders. 5th ed. Arlington, Va: American Psychiatric Publishing. 2013. Powell AD. Grief, bereavement, and adjustment disorders. In: Stern TA, Rosenbaum ...

  11. Unsteady blade pressures on a propfan at takeoff: Euler analysis and flight data

    NASA Technical Reports Server (NTRS)

    Nallasamy, M.

    1991-01-01

    The unsteady blade pressures due to the operation of the propfan at an angle to the direction of the mean flow are obtained by solving the unsteady three dimensional Euler equations. The configuration considered is the eight bladed SR7L propfan at takeoff conditions and the inflow angles considered are 6.3 deg, 8.3 deg, 11.3 deg. The predicted blade pressure waveforms are compared with inflight measurements. At the inboard radial station (r/R = 0.68) the phase of the predicted waveforms show reasonable agreement with the measurements while the amplitudes are over predicted in the leading edge region of the blade. At the outboard radial station (r/R = 0.95), the predicted amplitudes of the waveforms on the pressure surface are in good agreement with flight data for all inflow angles. The measured (installed propfan) waveforms show a relative phase lag compared to the computed (propfan alone) waveforms. The phase lag depends on the axial location of the transducer and the surface of the blade. On the suction surface, in addition to the relative phase lag, the measurements show distortion (widening and steepening) of the waveforms. The extent of distortion increases with increase in inflow angle. This distortion seems to be due to viscous separation effects which depend on the azimuthal location of the blade and the axial location of the transducer.

  12. SERI advanced wind turbine blades

    SciTech Connect

    Tangler, J.; Smith, B.; Jager, D.

    1992-02-01

    The primary goal of the Solar Energy Research Institute's (SERI) advanced wind turbine blades is to convert the kinetic energy in the wind into mechanical energy in an inexpensive and efficient manner. To accomplish this goal, advanced wind turbine blades have been developed by SERI that utilize unique airfoil technology. Performance characteristics of the advanced blades were verified through atmospheric testing on fixed-pitch, stall-regulated horizontal-axis wind turbines (HAWTs). Of the various wind turbine configurations, the stall-regulated HAWT dominates the market because of its simplicity and low cost. Results of the atmospheric tests show that the SERI advanced blades produce 10% to 30% more energy than conventional blades. 6 refs.

  13. SERI advanced wind turbine blades

    SciTech Connect

    Tangler, J.; Smith, B.; Jager, D.

    1992-02-01

    The primary goal of the Solar Energy Research Institute`s (SERI) advanced wind turbine blades is to convert the kinetic energy in the wind into mechanical energy in an inexpensive and efficient manner. To accomplish this goal, advanced wind turbine blades have been developed by SERI that utilize unique airfoil technology. Performance characteristics of the advanced blades were verified through atmospheric testing on fixed-pitch, stall-regulated horizontal-axis wind turbines (HAWTs). Of the various wind turbine configurations, the stall-regulated HAWT dominates the market because of its simplicity and low cost. Results of the atmospheric tests show that the SERI advanced blades produce 10% to 30% more energy than conventional blades. 6 refs.

  14. Low-Noise Rotorcraft Blades

    NASA Technical Reports Server (NTRS)

    Brooks, Thomas F.

    1994-01-01

    Blades of helicopter rotors, tilt rotors, and like reshaped to reduce noise, according to proposal. Planform features combination of rearward and forward sweep. Forward sweep over large outer portion of blade constitutes primary noise-reduction feature. Relieves some of compressive effect in tip region, with consequent reduction of noise from compressive sources. Performance at high advance ratio improved. Cabin vibration and loading noise reduced by load-averaging effect of double-sweep planform. Aft-swept section provides balancing of aerodynamic and other dynamic forces on blade along 1/4-chord line of straight inboard section and along projection of line to outermost blade radius. Possible for hub-hinge forces and moments to remain within practical bounds. Provides stabilizing blade forces and moments to counteract any instability caused by forward sweep.

  15. Design of centrifugal impeller blades

    NASA Technical Reports Server (NTRS)

    Betz, A; Flugge-Lotz, I

    1939-01-01

    This paper restricts itself to radial impellers with cylindrical blades since, as Prasil has shown, the flow about an arbitrarily curved surface of revolution may be reduced to this normal form we have chosen by a relatively simple conformal transformation. This method starts from the simple hypotheses of the older centrifugal impeller theory by first assuming an impeller with an infinite number of blades. How the flow is then modified is then investigated. For the computation of flow for a finite number of blades, the approximation method as developed by Munk, Prandtl and Birnbaum, or Glauert is found suitable. The essential idea of this method is to replace the wing by a vortex sheet and compute the flow as the field of these vortices. The shape of the blades is then obtained from the condition that the flow must be along the surface of the blade.

  16. SERI advanced wind turbine blades

    NASA Astrophysics Data System (ADS)

    Tangler, J.; Smith, B.; Jager, D.

    1992-02-01

    The primary goal of the Solar Energy Research Institute's (SERI) advanced wind turbine blades is to convert the kinetic energy in the wind into mechanical energy in an inexpensive and efficient manner. To accomplish this goal, advanced wind turbine blades have been developed by SERI that utilize unique airfoil technology. Performance characteristics of the advanced blades were verified through atmospheric testing on fixed-pitch, stall-regulated horizontal-axis wind turbines (HAWTs). Of the various wind turbine configurations, the stall-regulated HAWT dominates the market because of its simplicity and low cost. Results of the atmospheric tests show that the SERI advanced blades produce 10 percent to 30 percent more energy than conventional blades.

  17. Adjustable Powder Injector For Vacuum Plasma Sprayer

    NASA Technical Reports Server (NTRS)

    Burns, D. H.; Woodford, W. H.; Mckechnie, T. N.; Mcferrin, D. C.; Davis, W. M.; Beason, G. P., Jr.

    1993-01-01

    Attachment for plasma spray gun provides four degrees of freedom for adjustment of position and orientation at which powder injected externally into plasma flame. Manipulator provides for adjustment of pitch angle of injection tube: set to inject powder at any angle ranging from perpendicular to parallel to cylindrical axis. Scribed lines on extension bar and manipulator indicate pitch angle of extension tube. Collar changed to adapt injector to different gun.

  18. Incidence loss for a core turbine rotor blade in a two-dimensional cascade

    NASA Technical Reports Server (NTRS)

    Stabe, R. G.; Kline, J. F.

    1974-01-01

    The effect of incidence angle on the aerodynamic performance of an uncooled core turbine rotor blade was investigated experimentally in a two-dimensional cascade. The cascade test covered a range of incidence angles from minus 15 deg to 15 deg in 5-degree increments and a range of pressure ratios corresponding to ideal exit critical velocity ratios of 0.6 to 0.95. The principal measurements were blade-surface static pressures and cross-channel surveys of exit total pressure, static pressure, and flow angle. The results of the investigation include blade-surface velocity distribution and overall performance in terms of weight flow and loss for the range of incidence angles and exit velocity ratios investigated. The measured losses are also compared with two common methods of predicting incidence loss.

  19. Visualization study on the static flow field around a straight-bladed vertical axis wind turbine

    NASA Astrophysics Data System (ADS)

    Li, Yan; Tagawa, Kotaro

    2010-03-01

    Visual experiments based on the smoke wire way were carried out on a small model of Straight-blade Vertical Axis Wind Turbine (SB-VAWT) to invest the relationship between the static flow field characteristics and the rotor azimuth angle. The test rotor had 3 blades with NACA0018 aerofoil. The rotor diameter and blade chord were 0.3m and 0.07m, respectively. Visual photos of the static flow path lines in and around the rotor were obtained at every 5 degrees of the azimuth angle. Further, numerical computations of the static flow filed were also carried out for comparison with the same situation as the visual tests and the static torques at different azimuth angles were calculated. According to the results of visual tests and computations, the dependence of the starting performance on the azimuth angle was discussed. The solidity is an important factor affecting the starting performance of the SB-VAWT.

  20. Visualization study on the static flow field around a straight-bladed vertical axis wind turbine

    NASA Astrophysics Data System (ADS)

    Li, Yan; Tagawa, Kotaro

    2009-12-01

    Visual experiments based on the smoke wire way were carried out on a small model of Straight-blade Vertical Axis Wind Turbine (SB-VAWT) to invest the relationship between the static flow field characteristics and the rotor azimuth angle. The test rotor had 3 blades with NACA0018 aerofoil. The rotor diameter and blade chord were 0.3m and 0.07m, respectively. Visual photos of the static flow path lines in and around the rotor were obtained at every 5 degrees of the azimuth angle. Further, numerical computations of the static flow filed were also carried out for comparison with the same situation as the visual tests and the static torques at different azimuth angles were calculated. According to the results of visual tests and computations, the dependence of the starting performance on the azimuth angle was discussed. The solidity is an important factor affecting the starting performance of the SB-VAWT.

  1. Tiltrotor Research Aircraft composite blade repairs - Lessons learned

    NASA Technical Reports Server (NTRS)

    Espinosa, Paul S.; Groepler, David R.

    1992-01-01

    The XV-15, N703NA Tiltrotor Research Aircraft located at the NASA Ames Research Center, Moffett Field, California, currently uses a set of composite rotor blades of complex shape known as the advanced technology blades (ATBs). The main structural element of the blades is a D-spar constructed of unidirectional, angled fiberglass/graphite, with the aft fairing portion of the blades constructed of a fiberglass cross-ply skin bonded to a Nomex honeycomb core. The blade tip is a removable laminate shell that fits over the outboard section of the spar structure, which contains a cavity to retain balance weights. Two types of tip shells are used for research. One is highly twisted (more than a conventional helicopter blade) and has a hollow core constructed of a thin Nomex-honeycomb-and-fiberglass-skin sandwich; the other is untwisted with a solid Nomex honeycomb core and a fiberglass cross-ply skin. During initial flight testing of the blades, a number of problems in the composite structure were encountered. These problems included debonding between the fiberglass skin and the honeycomb core, failure of the honeycomb core, failures in fiberglass splices, cracks in fiberglass blocks, misalignment of mated composite parts, and failures of retention of metal fasteners. Substantial time was spent in identifying and repairing these problems. Discussed here are the types of problems encountered, the inspection procedures used to identify each problem, the repairs performed on the damaged or flawed areas, the level of criticality of the problems, and the monitoring of repaired areas. It is hoped that this discussion will help designers, analysts, and experimenters in the future as the use of composites becomes more prevalent.

  2. Tiltrotor research aircraft composite blade repairs: Lessons learned

    NASA Technical Reports Server (NTRS)

    Espinosa, Paul S.; Groepler, David R.

    1991-01-01

    The XV-15, N703NA Tiltrotor Research Aircraft located at the NASA Ames Research Center, Moffett Field, California, currently uses a set of composite rotor blades of complex shape known as the advanced technology blades (ATBs). The main structural element of the blades is a D-spar constructed of unidirectional, angled fiberglass/graphite, with the aft fairing portion of the blades constructed of a fiberglass cross-ply skin bonded to a Nomex honeycomb core. The blade tip is a removable laminate shell that fits over the outboard section of the spar structure, which contains a cavity to retain balance weights. Two types of tip shells are used for research. One is highly twisted (more than a conventional helicopter blade) and has a hollow core constructed of a thin Nomex-honeycomb-and-fiberglass-skin sandwich; the other is untwisted with a solid Nomex honeycomb core and a fiberglass cross-ply skin. During initial flight testing of the blades, a number of problems in the composite structure were encountered. These problems included debonding between the fiberglass skin and the honeycomb core, failure of the honeycomb core, failures in fiberglass splices, cracks in fiberglass blocks, misalignment of mated composite parts, and failures of retention of metal fasteners. Substantial time was spent in identifying and repairing these problems. Discussed here are the types of problems encountered, the inspection procedures used to identify each problem, the repairs performed on the damaged or flawed areas, the level of criticality of the problems, and the monitoring of repaired areas. It is hoped that this discussion will help designers, analysts, and experimenters in the future as the use of composites becomes more prevalent.

  3. Impact resistance of spar-shell composite fan blades

    NASA Technical Reports Server (NTRS)

    Graff, J.; Stoltze, L.; Varholak, E. M.

    1973-01-01

    Composite spar-shell fan blades for a 1.83 meter (6 feet) diameter fan stage were fabricated and tested in a whirling arm facility to evaluate foreign object damage (FOD) resistance. The blades were made by adhesively bonding boron-epoxy shells on titanium spars and then adhesively bonding an Inconel 625 sheath on the leading edge. The rotating blades were individually tested at a tip speed of 800 feet per second. Impacting media used were gravel, rivets, bolt, nut, ice balls, simulated birds, and a real bird. Incidence angles were typical of those which might be experienced by STOL aircraft. The tests showed that blades of the design tested in this program have satisfactory impact resistance to small objects such as gravel, rivets, nuts, bolts, and two inch diameter ice balls. The blades suffered nominal damage when impacted with one-pound birds (9 to 10 ounce slice size). However, the shell was removed from the spar for a larger slice size.

  4. Development of a centrifugal pump with thick blades.

    PubMed

    Kim, W G; Chung, C H; Yang, W S; Park, Y N; Kim, H I; Kim, H C; Kang, S H

    2000-02-01

    We have developed a centrifugal blood pump with thick impeller blades (60% of pitch) to obtain a small tip clearance. An unshrouded impeller with 6 backward curved thick blades was used to reduce the dead zone between the shroud and upper casing. A streamline angle in volute was uniform in circumferential direction by continuity and angular momentum conservation. To prove the effectiveness of small tip clearance, performance and hemolysis tests were conducted on pumps with a tip clearance of 0.5, 1.5, and 2.0 mm at exit with the blade thickness of 60% of pitch, and with that of 1.0, 2.0, and 2.5 mm at exit with the thickness of 40% of pitch. The results showed that the smaller the tip clearance, the better the hydrodynamic and hemolytic performance. The best result was seen in the pump with tip clearance of 0.5 mm with a blade thickness of 60% of pitch. These results suggest that a centrifugal pump with thick blades and a small tip clearance can be a promising alternative as a cardiopulmonary bypass pump. PMID:10718771

  5. Investigation of rotor blade roughness effects on turbine performance

    SciTech Connect

    Boynton, J.L.; Tabibzadeh, R. . Rocketdyne Div.); Hudson, S.T. )

    1993-07-01

    The cold air test program was completed on the SSME (Space Shuttle Main Engine) HPFTP (High-Pressure Fuel Turbopump) turbine with production nozzle vane rings and polished coated rotor blades with a smooth surface finish of 30[mu]in. (0.76 [mu]m) rms (root mean square). The smooth blades were polished by an abrasive flow machining process. The test results were compared with the air test results from production rough-coated rotor blades with a surface finish of up to 400 [mu]in. (10.16 [mu]m) rms. Turbine efficiency was higher for the smooth blades over the entire range tested. Efficiency increased 2.1 percentage points at the SSME 104 percent RPL (Rated Power Level) conditions. This efficiency improvement could reduce the SSME HPFTP turbine inlet temperature by 57 R (32K), increasing turbine durability. The turbine flow parameter increased and the midspan outlet swirl angle became more axial with the smooth rotor blades.

  6. The boundary layer on compressor cascade blades

    NASA Technical Reports Server (NTRS)

    Deutsch, S.; Zierke, W. C.

    1986-01-01

    The purpose of NASA Research Grant NSG-3264 is to characterize the flowfield about an airfoil in a cascade at chord Reynolds number(R sub C)near 5 x 10 to the 5th power. The program is experimental and combines laser Doppler velocimeter (LDV) measurements with flow visualization techniques in order to obtain detailed flow data, e.g., boundary layer profiles, points of separation and the transition zone, on a cascade of highly-loaded compressor blades. The information provided by this study is to serve as benchmark data for the evaluation of current and future compressor cascade predictive models, in this way aiding in the compressor design process. Summarized is the research activity for the period 1 December 1985 through 1 June 1986. Progress made from 1 June 1979 through 1 December 1985 is presented. Detailed measurements have been completed at the initial cascade angle of 53 deg. (incidence angle 5 degrees). A three part study, based on that data, has been accepted as part of the 1986 Gas Turbine Conference and will be submitted for subsequent journal publication. Also presented are data for a second cascade angle of 45 deg (an incidence angle of 3 degrees).

  7. Lift distribution and velocity field measurements for a three-dimensional, steady blade/vortex interaction

    NASA Technical Reports Server (NTRS)

    Dunagan, Stephen E.; Norman, Thomas R.

    1987-01-01

    A wind tunnel experiment simulating a steady three-dimensional helicopter rotor blade/vortex interaction is reported. The experimental configuration consisted of a vertical semispan vortex-generating wing, mounted upstream of a horizontal semispan rotor blade airfoil. A three-dimensional laser velocimeter was used to measure the velocity field in the region of the blade. Sectional lift coefficients were calculated by integrating the velocity field to obtain the bound vorticity. Total lift values, obtained by using an internal strain-gauge balance, verified the laser velocimeter data. Parametric variations of vortex strength, rotor blade angle of attack, and vortex position relative to the rotor blade were explored. These data are reported (with attention to experimental limitations) to provide a dataset for the validation of analytical work.

  8. Air stability of low-temperature dehydrogenation of Pd-decorated Mg blades.

    PubMed

    Liu, Yu; Wang, Gwo-Ching

    2012-01-20

    We demonstrated that Pd-decorated Mg blades are air-stable for hydrogen storage with a low desorption temperature of 373 K. Pd-catalyst-decorated Mg blades were prepared by 64° oblique incident angle thermal deposition on a rotatable substrate with the rotation axis perpendicular to the substrate. The hydrogen desorption from Pd-decorated Mg blades was performed and recorded by temperature-programmed desorption (TPD) for repeated hydrogenation–dehydrogenation cycles. The near-surface structural and compositional changes were characterized in situ by reflection high energy electron diffraction (RHEED). The Mg blades were intentionally exposed to air at elevated temperatures (333 or 358 K) between certain cycles. It was found that the degradation of the storage capacity was affected weakly by the air exposure at moderate temperatures. The kinetics of the hydrogen desorption was sensitive to air exposure but recoverable through a replenishment of fresh catalyst Pd on the surface of the oxidized Mg blades. PMID:22166731

  9. Blade Displacement Measurements of the Full-Scale UH-60A Airloads Rotor

    NASA Technical Reports Server (NTRS)

    Barrows, Danny A.; Burner, Alpheus W.; Abrego, Anita I.; Olson, Lawrence E.

    2011-01-01

    Blade displacement measurements were acquired during a wind tunnel test of the full-scale UH-60A Airloads rotor. The test was conducted in the 40- by 80-Foot Wind Tunnel of the National Full-Scale Aerodynamics Complex at NASA Ames Research Center. Multi-camera photogrammetry was used to measure the blade displacements of the four-bladed rotor. These measurements encompass a range of test conditions that include advance ratios from 0.15 to unique slowed-rotor simulations as high as 1.0, thrust coefficient to rotor solidity ratios from 0.01 to 0.13, and rotor shaft angles from -10.0 to 8.0 degrees. The objective of these measurements is to provide a benchmark blade displacement database to be utilized in the development and validation of rotorcraft computational tools. The methodology, system development, measurement techniques, and preliminary sample blade displacement measurements are presented.

  10. Dynamic-stall and structural-modeling effects on helicopter blade stability with experimental correlation

    NASA Technical Reports Server (NTRS)

    Barwey, D.; Gaonkar, Gopal H.

    1994-01-01

    The effects of blade and root-flexure elasticity and dynamic stall on the stability of hingeless rotor blades are investigated. The dynamic stall description is based on the ONERA models of lift, drag, and pitching moment. The structural analysis is based on three blade models that range from a rigid flap-lag model to two elastic flap-lag-torsion models, which differ in representing root-flexure elasticity. The predictions are correlated with the measured lag damping of an experimental isolated three-blade rotor; the correlation covers rotor operations from near-zero-thrust conditions in hover to highly stalled, high-thrust conditions in foward flight. That correlation shows sensitivity of lag-damping predictions to structural refinements in blade and root-flexure modeling. Moreover, this sensitivity increases with increasing control pitch angle and advance ratio. For high-advance-ratio and high-thrust conditions, inclusion of dynamic stall generally improves the correlation.

  11. Holographic flow visualization within a rotating compressor blade row

    NASA Technical Reports Server (NTRS)

    Benser, W. A.

    1975-01-01

    Rapid double-pulsed holographic techniques were used to visualize the shock configurations in the tip region of a lightly loaded, high tip speed fan stage. The holograms showed the passage shock emanating from the blade leading edge, a moderately strong conical shock originating at the intersection of the part span shroud leading edge and the blade suction surface, and a second conical shock originating at the intersection of the part span shroud and the blade pressure surface. Due to a limited viewing angle, the bow waves upstream of the rotor could not be observed, and only limited details of the trailing edge shocks were obtained. Reasonable details of the shock patterns were obtained from holograms which were made without extensive rig modifications. Results indicate that larger viewing windows and and holographic plates would permit a wider viewing angle and give much more coverage of the regions of interest. Also, shorter time delay for double-pulsed holograms is also desirable, and would minimize blade movement and give clearer holograms.

  12. Dynamic stall of an experimental wind turbine blade

    NASA Astrophysics Data System (ADS)

    Melius, Matthew; Cal, Raúl Bayoán; Mulleners, Karen

    2016-03-01

    To understand the complex flow phenomena over wind turbine blades during stall development, a scaled three-dimensional non-rotating blade model is designed to be dynamically similar to a rotating full-scale NREL 5 MW wind turbine blade. A time-resolved particle image velocimetry (PIV) investigation of flow behavior during the stall cycle examines the processes of stall development and flow reattachment. Proper orthogonal decomposition (POD) and vortex detection techniques are applied to the PIV fields to quantify relevant flow characteristics such as vortex size, separation angle, and separation point throughout a dynamic pitching cycle. The behavior of the POD coefficients provides time scales for the transitional stages which are quantified and compared, revealing that transition from attached flow to full stall is delayed to higher angles of attack and occurs at a higher rate than the transition from full stall to attached flow. The instantaneous flow fields are then reconstructed using the first four POD modes to demonstrate their prominent roles throughout the stall cycle and their ability to capture the general separation behavior over the blade surface.

  13. Investigation of the unsteady pressure distribution on the blades of an axial flow fan

    NASA Technical Reports Server (NTRS)

    Henderson, R. E.; Franke, G. F.

    1978-01-01

    The unsteady response of a stator blade caused by the interaction of the stator with the wakes of an upstream rotor was investigated. Unsteady pressure distributions were measured using a blade instrumented with a series miniature pressure transducers. The influence of several geometrical and flow parameters - rotor/stator spacing, stator solidity and stator incidence angle - were studied to determine the unsteady response of the stator to these parameters. A major influence on the stator unsteady response is due to the stator solidity. At high solidities the blade-to-blade interference has a larger contribution. While the range of rotor/stator spacings investigated had a minor influence, the effect of stator incidence angle is significant. The data indicate the existence of an optimum positive incidence which minimizes the unsteady response.

  14. Turbine blade cooling

    DOEpatents

    Staub, Fred Wolf; Willett, Fred Thomas

    1999-07-20

    A turbine rotor blade comprises a shank portion, a tip portion and an airfoil. The airfoil has a pressure side wall and a suction side wall that are interconnected by a plurality of partition sidewalls, defining an internal cooling passageway within the airfoil. The internal cooling passageway includes at least one radial outflow passageway to direct a cooling medium flow from the shank portion towards the tip portion and at least one radial inflow passageway to direct a cooling medium flow from the tip portion towards the shank portion. A number of mixing ribs are disposed on the partition sidewalls within the radial outflow passageways so as to enhance the thermal mixing of the cooling medium flow, thereby producing improved heat transfer over a broad range of the Buoyancy number.

  15. Turbine blade cooling

    DOEpatents

    Staub, Fred Wolf; Willett, Fred Thomas

    2000-01-01

    A turbine rotor blade comprises a shank portion, a tip portion and an airfoil. The airfoil has a pressure side wall and a suction side wall that are interconnected by a plurality of partition sidewalls, defining an internal cooling passageway within the airfoil. The internal cooling passageway includes at least one radial outflow passageway to direct a cooling medium flow from the shank portion towards the tip portion and at least one radial inflow passageway to direct a cooling medium flow from the tip portion towards the shank portion. A number of mixing ribs are disposed on the partition sidewalls within the radial outflow passageways so as to enhance the thermal mixing of the cooling medium flow, thereby producing improved heat transfer over a broad range of the Buoyancy number.

  16. Turbine blade cooling

    SciTech Connect

    Staub, F.W.; Willett, F.T.

    1999-07-20

    A turbine rotor blade comprises a shank portion, a tip portion and an airfoil. The airfoil has a pressure side wall and a suction side wall that are interconnected by a plurality of partition sidewalls, defining an internal cooling passageway within the airfoil. The internal cooling passageway includes at least one radial outflow passageway to direct a cooling medium flow from the shank portion towards the tip portion and at least one radial inflow passageway to direct a cooling medium flow from the tip portion towards the shank portion. A number of mixing ribs are disposed on the partition sidewalls within the radial outflow passageways so as to enhance the thermal mixing of the cooling medium flow, thereby producing improved heat transfer over a broad range of the Buoyancy number. 13 figs.

  17. Multiple piece turbine blade

    DOEpatents

    Kimmel, Keith D

    2012-05-29

    A turbine rotor blade with a spar and shell construction, the spar including an internal cooling supply channel extending from an inlet end on a root section and ending near the tip end, and a plurality of external cooling channels formed on both side of the spar, where a middle external cooling channel is connected to the internal cooling supply channels through a row of holes located at a middle section of the channels. The spar and the shell are held together by hooks that define serpentine flow passages for the cooling air and include an upper serpentine flow circuit and a lower serpentine flow circuit. the serpentine flow circuits all discharge into a leading edge passage or a trailing edge passage.

  18. Turbine Blade Alloy

    NASA Technical Reports Server (NTRS)

    MacKay, Rebecca

    2001-01-01

    The High Speed Research Airfoil Alloy Program developed a fourth-generation alloy with up to an +85 F increase in creep rupture capability over current production airfoil alloys. Since improved strength is typically obtained when the limits of microstructural stability are exceeded slightly, it is not surprising that this alloy has a tendency to exhibit microstructural instabilities after high temperature exposures. This presentation will discuss recent results obtained on coated fourth-generation alloys for subsonic turbine blade applications under the NASA Ultra-Efficient Engine Technology (UEET) Program. Progress made in reducing microstructural instabilities in these alloys will be presented. In addition, plans will be presented for advanced alloy development and for computational modeling, which will aid future alloy development efforts.

  19. Induced strain actuation of composite beams and rotor blades with embedded piezoceramic elements

    NASA Astrophysics Data System (ADS)

    Chen, Peter C.; Chopra, Inderjit

    1996-02-01

    The objective of this research is to develop a dynamically-scaled (Froude scale) helicopter rotor blade with embedded piezoceramic elements as sensors and actuators to control blade vibrations. A 6 ft diameter 2-bladed bearingless rotor model was built where each blade is embedded with banks of piezoelectric actuators at 0964-1726/5/1/005/img1 degree angles with respect to the beam axis on the top and bottom surfaces. A twist distribution along the blade span is achieved through in-phase excitation of the top and bottom actuators at equal potentials, while a bending distribution is achieved through out-of-phase excitation. In order to fix design variables and to optimize blade performance, a uniform strain beam theory is formulated to analytically predict the static bending and torsional response of composite rectangular beams with embedded piezoelectric actuators. Parameters such as bond thicknesses, actuator skew angle and actuator spacing are investigated by experiments and then validated by theory. The static bending and torsional response of the rotor blades is experimentally measured and correlated with theory. Dynamic torsional and bending responses are experimentally determined for frequencies from 2 - 120 Hz to assess the viability of a vibration reduction system based on piezo-actuation of blade twist. To assess the performance of the piezo-actuators in rotation, hover tests were conducted where accelerometers embedded in the blades were used to resolve the tip twist amplitudes. Although the magnitudes of blade twist attained in this experiment were small, it is expected that future models can be built with improved performance.

  20. Design and two dimensional cascade test of a jet-flap turbine stator blade with ratio of axial chord to spacing of 0.5

    NASA Technical Reports Server (NTRS)

    Stabe, R. G.

    1971-01-01

    A jet-flap blade was designed for a velocity diagram typical of the first-stage stator of a jet engine turbine and was tested in a simple two-dimensional cascade of six blades. The principal measurements were blade surface static pressure and cross-channel surveys of exit total pressure, static pressure, and flow angle. The results of the experimental investigation include blade loading, exit angle, flow, and loss data for a range of exit critical velocity ratios and three jet flow conditions.

  1. Single-stage experimental evaluation of tandem-airfoil rotor and stator blading for compressors. Part 5: Analysis and design of stages D and E

    NASA Technical Reports Server (NTRS)

    Brent, J. A.; Cheatham, J. G.; Clemmons, D. R.

    1972-01-01

    A conventional and a tandem bladed stage were designed for a comparative experimental evaluation in a 0.8 hub/tip ratio single-stage compressor. Based on a preliminary design study, a radially constant work input distribution was selected for the rotor designs. Velocity diagrams and blade leading and trailing edge angles selected for the conventional rotor and stator were used in the design of the tandem blading. The effects of axial velocity ratio and secondary flow on turning were included in the selection of blade leading and trailing edge angles. Design values of rotor tip velocity and stage pressure ratio were 757 ft/sec and 1.26, respectively.

  2. Novel Compressor Blade Design Study

    NASA Astrophysics Data System (ADS)

    Srinivas, Abhay

    Jet engine efficiency goals are driving compressors to higher pressure ratios and engines to higher bypass ratios, each one driving to smaller cores. This is leading to larger tip gaps relative to the blade height. These larger relative tip clearances would negate some of the cycle improvements, and ways to mitigate this effect must be found. A novel split tip blade geometry has been created which helps improve the efficiency at large clearances while also improving operating range. Two identical blades are leaned in opposite directions starting at 85% span. They are cut at mid chord and the 2 halves then merged together so a split tip is created. The result is similar to the alula feathers on a soaring bird. The concept is that the split tip will energize the tip flow and increase range. For higher relative tip clearance, this will also improve efficiency. The 6th rotor of a highly loaded 10 stage machine was chosen as the baseline for this study. Three dimensional CFD simulations were performed using CD Adapco's Star-CCM+ at 5 clearances for the baseline and split tip geometry. The choking flow and stall margin of the split tip blade was higher than that of the baseline blade for all tip clearances. The pressure ratio of the novel blade was higher than that of the baseline blade near choke, but closer to stall it decreased. The sensitivity of peak efficiency to clearance was improved. At tight clearances of 0.62% of blade height, the maximum efficiency of the new design was less than the baseline blade, but as the tip clearance was increased above 2.5%, the maximum efficiency increased. Structural analysis was also performed to ascertain the feasibility of the design.

  3. Blade loss transient dynamics analysis with flexible bladed disk

    NASA Technical Reports Server (NTRS)

    Gallardo, V. C.; Black, G.; Bach, L.; Cline, S.; Storace, A.

    1983-01-01

    The transient dynamic response of a flexible bladed disk on a flexible rotor in a two rotor system is formulated by modal synthesis and a Lagrangian approach. Only the nonequilibrated one diameter flexible mode is considered for the flexible bladed disk, while the two flexible rotors are represented by their normal modes. The flexible bladed disk motion is modeled as a combination of two one diameter standing waves, and is coupled inertially and gyroscopically to the flexible rotors. Application to a two rotor model shows that a flexible bladed disk on one rotor can be driven into resonance by an unbalance in the other rotor, and at a frequency equal to the difference in the rotor speeds.

  4. Optical Blade Position Tracking System Test

    SciTech Connect

    Fingersh, L. J.

    2006-01-01

    The Optical Blade Position Tracking System Test measures the blade deflection along the span of the blade using simple off-the-shelf infrared security cameras along with blade-mounted retro-reflective tape and video image processing hardware and software to obtain these measurements.

  5. Apparatus for loading a band saw blade

    DOEpatents

    Reeves, Steven R.

    1990-01-01

    A band saw blade is loaded between pairs of guide wheels upon tensioning the blade by guiding the blade between pairs of spaced guide plates which define converging slots that converge toward the guide wheels. The approach is particularly useful in loading blades on underwater band saw machines used to cut radioactive materials.

  6. Wooden wind turbine blade manufacturing process

    DOEpatents

    Coleman, Clint

    1986-01-01

    A wooden wind turbine blade is formed by laminating wood veneer in a compression mold having the exact curvature needed for one side of the blade, following which the other side of the blade is ground flat along its length but twisted with respect to the blade axis.

  7. Containment of composite fan blades

    NASA Technical Reports Server (NTRS)

    Stotler, C. L.; Coppa, A. P.

    1979-01-01

    A lightweight containment was developed for turbofan engine fan blades. Subscale ballistic-type tests were first run on a number of concepts. The most promising configuration was selected and further evaluated by larger scale tests in a rotating test rig. Weight savings made possible by the use of this new containment system were determined and extrapolated to a CF6-size engine. An analytical technique was also developed to predict the released blades motion when involved in the blade/casing interaction process. Initial checkout of this procedure was accomplished using several of the tests run during the program.

  8. Optical Detection of Blade Flutter

    NASA Technical Reports Server (NTRS)

    Nieberding, W. C.; Pollack, J. L.

    1977-01-01

    Dynamic strain gages mounted on rotor blades are used as the primary instrumentation for detecting the onset of flutter and defining the vibratory mode and frequency. Optical devices are evaluated for performing the same measurements as well as providing supplementary information on the vibratory characteristics. Two separate methods are studied: stroboscopic imagery of the blade tip and photoelectric scanning of blade tip motion. Both methods give visual data in real time as well as video tape records. The optical systems are described, and representative results are presented. The potential of this instrumentation in flutter research is discussed.

  9. Method and apparatus for reducing rotor blade deflections, loads, and/or peak rotational speed

    DOEpatents

    Moroz, Emilian Mieczyslaw; Pierce, Kirk Gee

    2006-10-17

    A method for reducing at least one of loads, deflections of rotor blades, or peak rotational speed of a wind turbine includes storing recent historical pitch related data, wind related data, or both. The stored recent historical data is analyzed to determine at least one of whether rapid pitching is occurring or whether wind speed decreases are occurring. A minimum pitch, a pitch rate limit, or both are imposed on pitch angle controls of the rotor blades conditioned upon results of the analysis.

  10. Review of high-performance axial-flow-compressor blade-element theory

    NASA Technical Reports Server (NTRS)

    Lieblein, Seymour

    1954-01-01

    This report presents a review of current compressor blade-element theory with particular emphasis on application to the transonic high-performance compressor. A discussion of the significant parameters of total-pressure loss and deviation angle is presented, and an indication of the extent of available knowledge and the problems involved in the determination of blade-element characteristics is given. Some recent results and considerations in this pursuit and suggestions for further avenues of investigation are indicated.

  11. Rotating vibration behavior of the turbine blades with different groups of blades

    NASA Astrophysics Data System (ADS)

    Tsai, Gwo-Chung

    2004-04-01

    The rotating vibration behaviors of full cycle of 60 blades are studied in this report. The dynamic analysis of two different structures in one of which there are 10 groups of 6 blades and in the other 5 groups of 12 blades, is performed to investigate behavior deviation. In this research, the following jobs are considered: (1) collect the geometric dimensions and material properties of a single blade, (2) create the finite element model of a single blade, a group of 6 blades and 12 blades, and full cycle of 60 blades, (3) perform the vibration analyses of a single blade, a group of blades and a full circle of 60 blades, (4) perform the steady state stress analysis of the blade with different rotating speed; (5) get the Campbell diagram for the full circle of blades, and (6) make comparisons between a group of 6 blades and a group of 12 blades. The conclusions from the analyses are the following: (1) the contact elements are applied to groups of 6 and 12 blades systems and the highest stresses are observed at the location of the first neck of the blade root. These results completely agree very well with in-site observations. (2) The big differences were present in the Campbell diagram: resonant frequencies are observed in the first vibration group for the full system comprising the group of 6 blades and resonant frequencies are not found in the first vibration group of the full blade system made of the group of 12 blades. (3) The dynamic behavior of the full blade system comprised of a group of 6 blades was found much different from that of the full blade system made is of a group of 12 blades. (4) Excellent agreements for the vibration frequencies and mode shapes of a single blade and a full circle of blades are obtained between the FEA results and experimental data.

  12. Wind-Tunnel Tests of a Portion of a PV-2 Helicopter Rotor Blade

    NASA Technical Reports Server (NTRS)

    Kemp, William B., Jr.

    1945-01-01

    A portion of a PV-2 helicopter rotor blade has been tested in the 6- by 6-foot test section of the Langley stability tunnel to determine if the aerodynamic characteristics were seriously affected by cross flow or fabric distortion. The outer portion of the blade was tested as a reflection plane model pivoted about the tunnel wall to obtain various angles of cross flow over the blade. Because the tunnel wall acts as a plane of sytry, the measured aerodynamic characteristics correspond to those of an airfoil having various angles of sweepforward and sweepback. Tests were made with the vents on the lower surface open and also with the vents sealed and the internal pressure held at -20 inches of water producing an internal pressure coefficient of -1.059. The change in contour resulting from the range of internal pressures used had very little effect on the aerodynamic characteristics of the blade. The test methods were considered to simulate inadequately the flow conditions over the rotor blade because the effects of cross flow were limited to conditions corresponding to sweep of the blade. The results indicated that this type of cross flow had only minor effects on the aerodynamic characteristics of the blade. It is believed, therefore, that future tests to determine the effects on the aerodynamic characteristics of cross flow should utilize complete rotors.

  13. Cascade tests of serrated leading edge blading at high subsonic speeds

    NASA Technical Reports Server (NTRS)

    Smith, E. G.

    1974-01-01

    Cascade tests of two-dimensional fan rotor blade rows were performed to investigate the effects of leading edge serration on acoustic and aerodynamic performance. The test configurations covered a range of serration tooth geometries. Tests were performed to investigate effects of inlet air angle and velocity on performance. Aerodynamic performance was determined by flow surveys at the mid-span of the blade exit. Acoustic performance was determined by wake turbulence surveys and sound measurements in the semireverberent exhaust chamber. Measured acoustic and aerodynamic performance was comparable and indicated that a serration length of about six percent blade chord yields minimum noise generation and minimum total pressure losses.

  14. Adjustable microforceps.

    PubMed

    Bao, J Y

    1991-04-01

    The commonly used microforceps have a much greater opening distance and spring resistance than needed. A piece of plastic ring or rubber band can be used to adjust the opening distance and reduce most of the spring resistance, making the user feel more comfortable and less fatigued. PMID:2051437

  15. Blade Manufacturing Improvement Project: Final Report

    SciTech Connect

    SHERWOOD, KENT

    2002-10-01

    The Blade Manufacturing Improvement Project explores new, unique and improved materials integrated with innovative manufacturing techniques that promise substantial economic enhancements for the fabrication of wind turbine blades. The primary objectives promote the development of advanced wind turbine blade manufacturing in ways that lower blade costs, cut rotor weight, reduce turbine maintenance costs, improve overall turbine quality and increase ongoing production reliability. Foam Matrix (FMI) has developed a wind turbine blade with an engineered foam core, incorporating advanced composite materials and using Resin Transfer Molding (RTM) processes to form a monolithic blade structure incorporating a single molding tool. Patented techniques are employed to increase blade load bearing capability and insure the uniform quality of the manufactured blade. In production quantities, FMI manufacturing innovations may return a sizable per blade cost reduction when compared to the cost of producing comparable blades with conventional methods.

  16. Impact behavior of filament-wound graphite/epoxy fan blades. [foreign object damage to turbofan engines

    NASA Technical Reports Server (NTRS)

    Bowles, K. J.

    1978-01-01

    The fabrication and impact tests of graphite/epoxy filament wound fan blades are discussed. Blades which were spin tested at tip speeds up to 305 m/sec retained their structural integrity. Two blades were each impacted with a 454-g slice of a 908-g simulated bird at a tip speed of 263 deg and impact angles of 22 deg and 32 deg. The impact tests were recorded with high-speed movie film. The blade which was impacted at 22 deg sustained some root delamination but remained intact. The 32 deg impact separated the blade from the root. No local damage other than leading-edge debonding was observed for either blade. The results of a failure mode analysis are also discussed.

  17. Unsteady internal flow conditions of mini-centrifugal pump with splitter blades

    NASA Astrophysics Data System (ADS)

    Shigemitsu, T.; Fukutomi, J.; Kaji, K.; Wada, T.

    2013-02-01

    Mini centrifugal pumps having a diameter smaller than 100mm are employed in many fields. But the design method for the mini centrifugal pump is not established because the internal flow condition for these small-sized fluid machines is not clarified and conventional theory is not suitable for small-sized pumps. Therefore, mini centrifugal pumps with simple structure were investigated by this research. Splitter blades were adopted in this research to improve the performance and the internal flow condition of mini centrifugal pump which had large blade outlet angle. The original impeller without the splitter blades and the impeller with the splitter blades were prepared for experiment. The performance tests are conducted with these rotors in order to investigate the effect of the splitter blades on performance and internal flow condition of mini centrifugal pump. On the other hand, a three dimensional unsteady numerical flow analysis was conducted to investigate the change of the internal flow according to the rotor rotation. It is clarified from the experimental results that the performance of the mini centrifugal pump is improved by the splitter blades. The blade-to-blade low velocity region was suppressed in the case with the splitter blades. In addition to that, the unsteady flows near the volute casing tongue were suppressed due to the splitter blades. In the present paper, the performance of the mini centrifugal pump is shown and the unsteady flow condition is clarified with the results of the numerical flow analysis. Furthermore, the effects of the splitter blades on the performance and the unsteady internal flow condition are investigated.

  18. Summary of Full-Scale Blade Displacement Measurements of the UH- 60A Airloads Rotor

    NASA Technical Reports Server (NTRS)

    Abrego, Anita I.; Meyn, Larry; Burner, Alpheus W.; Barrows, Danny A.

    2016-01-01

    Blade displacement measurements using multi-camera photogrammetry techniques were acquired for a full-scale UH-60A rotor, tested in the National Full-Scale Aerodynamic Complex 40-Foot by 80-Foot Wind Tunnel. The measurements, acquired over the full rotor azimuth, encompass a range of test conditions that include advance ratios from 0.15 to 1.0, thrust coefficient to rotor solidity ratios from 0.01 to 0.13, and rotor shaft angles from -10.0 to 8.0 degrees. The objective was to measure the blade displacements and deformations of the four rotor blades and provide a benchmark blade displacement database to be utilized in the development and validation of rotorcraft prediction techniques. An overview of the blade displacement measurement methodology, system development, and data analysis techniques are presented. Sample results based on the final set of camera calibrations, data reduction procedures and estimated corrections that account for registration errors due to blade elasticity are shown. Differences in blade root pitch, flap and lag between the previously reported results and the current results are small. However, even small changes in estimated root flap and pitch can lead to significant differences in the blade elasticity values.

  19. Spline for blade grids design

    NASA Astrophysics Data System (ADS)

    Korshunov, Andrei; Shershnev, Vladimir; Korshunova, Ksenia

    2015-08-01

    Methods of designing blades grids of power machines, such as equal thickness shape built on middle-line arc, or methods based on target stress spreading were invented long time ago, well described and still in use. Science and technology has moved far from that time and laboriousness of experimental research, which were involving unique equipment, requires development of new robust and flexible methods of design, which will determine the optimal geometry of flow passage.This investigation provides simple and universal method of designing blades, which, in comparison to the currently used methods, requires significantly less input data but still provides accurate results. The described method is purely analytical for both concave and convex sides of the blade, and therefore lets to describe the curve behavior down the flow path at any point. Compared with the blade grid designs currently used in industry, geometric parameters of the designs constructed with this method show the maximum deviation below 0.4%.

  20. Ceramic blade with tip seal

    DOEpatents

    Glezer, Boris; Bhardwaj, Narender K.; Jones, Russell B.

    1997-01-01

    The present gas turbine engine (10) includes a disc assembly (64) defining a disc (66) having a plurality of blades (70) attached thereto. The disc (66) has a preestablished rate of thermal expansion and the plurality of blades have a preestablished rate of thermal expansion being less than the preestablished rate of thermal expansion of the disc (66). A shroud assembly (100) is attached to the gas turbine engine (10) and is spaced from the plurality of blades (70) a preestablished distance forming an interface (108) therebetween. Positioned in the interface is a seal (110) having a preestablished rate of thermal expansion being generally equal to the rate of thermal expansion of the plurality of blades (70).

  1. A new experimental approach to study helicopter blade-vortex interaction noise

    NASA Astrophysics Data System (ADS)

    Koushik, Sudarshan N.

    A unique and novel experimental approach has been developed to study the aerodynamics and acoustics of the helicopter Blade-Vortex Interaction in a controlled hover environment. This is achieved by having a non-lifting single-bladed rotor with a rigid hub interact with a carefully controlled gust disturbance that replicates the essential characteristics of the vortex velocity. This experimental approach termed the Blade-Controlled Disturbance-Interaction or the BCDI, decouples the rotor parameters from the charactersitics of the incident disturbance velocity, thus providing an ideal setup for studying the blade's aerodynamics and acoustic response in detail. Moreover, the angle of interaction between the disturbance field and the rotor blade can be controlled by orienting the gust, providing the ability to study both parallel and oblique interactions. The noise data was recorded at thirty different microphone locations. A series of experiments at various rotor tip Mach numbers and interaction angles, replicating many of the conditions of helicopter BVI, were performed. The results show that the the directionality of the BVI noise is strongly determined by the interaction angle. A small change in interaction angle results in the radiation of noise over a larger azimuthal area compared to the parallel interaction. Moreover, as the interaction becomes more oblique, the peak noise elevation angle approaches closer to the rotor plane. A linear unsteady lifting-line aerodynamic theory (corrected for chord-wise non-compactness) was used to estimate the blade aerodynamics during the interaction and hence the radiated noise. Although the theory under-predicted the noise levels for most of the cases, and did not replicate exactly the general pulse shape, the general directionality trends were predicted reasonably well. The theory was used to separate the contribution to the acoustics, from different spanwise blade sections, providing significant insights into the phasing

  2. Automatic measurement of blade profile

    NASA Astrophysics Data System (ADS)

    Dong, Benhan; Liu, Lang; Liu, Wei; Gao, Penfei

    2002-05-01

    In this paper a newly developed 3D surface shape measuring system together with its application to the metrology of surface form of blade. The experiment shows that 3D500 measuring system is a useful tool for surface evaluation with character of full-field, on-line, real-time measurement that are important to the quality control inspection of the profile of turbine blade.

  3. Adjustable cutting guide aligns and positions stacks of material

    NASA Technical Reports Server (NTRS)

    Thiel, A. M.

    1966-01-01

    Adjustable guide tool aligns and positions stacks of material for cutting at various angles. The device adapts its shape to stacks of any corner angle, adjusts to any cutting angle, and quickly aligns the stacks for repeated cutting. With this device, an operator need not place his hands under the knife during alignment.

  4. Aerodynamic Characteristics of a Two-blade NACA 10-(3)(062)-045 Propeller and of a Two-blade NACA 10-(3)(08)-045 Propeller

    NASA Technical Reports Server (NTRS)

    Solomon, William

    1953-01-01

    Characteristics are given for the two-blade NACA 10-(3)(062)-045 propeller and for the two-blade NACA 10-(3)(08)-045 propeller over a range of advance ratio from 0.5 to 3.8, through a blade-angle range from 20 degrees to 55 degrees measured at the 0.75 radius. Maximum efficiencies of the order of 91.5 to 92 percent were obtained for the propellers. The propeller with the thinner airfoil sections over the outboard portion of the blades, the NACA 10-(3)(062)-045 propeller, had lower losses at high tip speeds, the difference amounting to about 5 percent at a helical tip Mach number of 1.10.

  5. Mechanism For Adjustment Of Commutation Of Brushless Motor

    NASA Technical Reports Server (NTRS)

    Schaefer, Richard E.

    1995-01-01

    Mechanism enables adjustment of angular position of set of Hall-effect devices that sense instantaneous shaft angle of brushless dc motor. Outputs of sensors fed to commutation circuitry. Measurement of shaft angle essential for commutation; that is, application of voltage to stator windings must be synchronized with shaft angle. To obtain correct angle measurement for commutation, Hall-effect angle sensors positioned at proper reference angle. The present mechanism accelerates adjustment procedure and makes it possible to obtain more accurate indication of minimum-current position because it provides for adjustment while motor running.

  6. Blade tip timing (BTT) uncertainties

    NASA Astrophysics Data System (ADS)

    Russhard, Pete

    2016-06-01

    Blade Tip Timing (BTT) is an alternative technique for characterising blade vibration in which non-contact timing probes (e.g. capacitance or optical probes), typically mounted on the engine casing (figure 1), and are used to measure the time at which a blade passes each probe. This time is compared with the time at which the blade would have passed the probe if it had been undergoing no vibration. For a number of years the aerospace industry has been sponsoring research into Blade Tip Timing technologies that have been developed as tools to obtain rotor blade tip deflections. These have been successful in demonstrating the potential of the technology, but rarely produced quantitative data, along with a demonstration of a traceable value for measurement uncertainty. BTT technologies have been developed under a cloak of secrecy by the gas turbine OEM's due to the competitive advantages it offered if it could be shown to work. BTT measurements are sensitive to many variables and there is a need to quantify the measurement uncertainty of the complete technology and to define a set of guidelines as to how BTT should be applied to different vehicles. The data shown in figure 2 was developed from US government sponsored program that bought together four different tip timing system and a gas turbine engine test. Comparisons showed that they were just capable of obtaining measurement within a +/-25% uncertainty band when compared to strain gauges even when using the same input data sets.

  7. The Effect of High Solidity on Propeller Characteristics at High Forward Speeds from Wind-Tunnel Tests of the NACA 4-(3)(06.3)-06 and NACA 4-(3)(06.4)-09 Two-Blade Propellers

    NASA Technical Reports Server (NTRS)

    Delano, James B.

    1947-01-01

    Tests of two-blade propellers having the NACA 4-(3)(06.3)-06 and NACA 4-(3)(06.4)-09 blade designs (blade activity factors of 179 and 263, respectively) have been made in the Langley 8-foot high-speed tunnel through a range of blade angle from 20 degrees to 70 degrees for free-stream Mach numbers from 0.165 to 0.725 to determine the effects of high solidity and compressibility on propeller characteristics. The tests are part of a general investigation of propellers at high forward speeds. Results previously reported for similar tests of two-blade propellers having the NACA 4-308-03 and NACA 4-308-045 blade designs (blade activity factors of 87 and 133, respectively) are included for comparison. The results showed that the 0.06- and 0.09-solidity blades, although producing efficiencies of the order of 90 percent, were less efficient than blades of conventional solidity. The variation in average blade lift coefficient with solidity at a constant blade angle and advance-diameter ratio through the speed range of these tests was found to be analogous to the variation of wing lift coefficient with aspect ratio, indicating that high-solidity blades may be desirable at very high speeds. Because of power limitations of the test equipment, conclusive evidence of the possible favorable effects of increased blade solidity at high speeds was not obtained. Further tests are desirable.

  8. Advanced turboprop wing installation effects measured by unsteady blade pressure and noise

    NASA Technical Reports Server (NTRS)

    Heidelberg, Laurence J.; Woodward, Richard P.

    1987-01-01

    A single rotation model propeller (SR-7A) was tested at simulated takeoff/approach conditions (Mach 0.2), in the NASA Lewis 9- by 15-Ft Anechoic Wind Tunnel. Both unsteady blade surface pressures and noise measurements were made for a tractor configuration with propeller/straight wing and propeller alone configurations. The angle between the wing chord and propeller axis (droop angle) was varied along with the wing angle of attack to determine the effects on noise and unsteady loading. A method was developed that uses unsteady blade pressure measurements to provide a quantitative indication of propeller inflow conditions, at least for a uniform (across the propeller disk) inflow angle. The wing installation caused a nearly uniform upwash at the propeller inlet as evidenced by the domination of the pressure spectra by the first shaft order. This inflow angle increased at a rate of almost 150 percent of that of the wing angle-of-attack for a propeller-wing spacing of 0.54 wing chords at a constant droop angle. The flyover noise, as measured by the maximum blade passing frequency level, correlates closely with the propeller inflow angle (approx. 0.6 dB per degree of inflow angle) for all droop angles and wing angles of attack tested, including the propeller alone data. Large changes in the unsteady pressure responses on the suction surface of the blade were observed as the advance ratio was varied. The presence of a leading edge vortex may explain this behavior since changes in the location of this vortex would change with loading (advance ratio).

  9. Development and performance of a large-scale, transonic turbine blade cascade facility for aerodynamic studies of merging coolant-mainstream flows

    NASA Astrophysics Data System (ADS)

    Al-Sayeh, Amjad Isaaf

    1998-11-01

    A new, large scale, linear cascade facility of turbine blades has been developed for the experimental exploration of the aerodynamic aspects of film cooling technology. Primary interest is in the mixing of the ejected coolant with the mainstream, at both subsonic and supersonic mainstream Mach numbers at the cascade exit. In order to achieve a spatial resolution adequate for the exploration of details on the scale of the coolant ejection holes, the cascade dimensions were maximized, within the limitations of the air supply system. The cascade contains four blades (three passages) with 14.05 cm axial chord, 17.56 cm span and a design total turning angle of 130.6 degrees. Exit Mach numbers range from 0.6 to 1.5 and Reynolds numbers from 0.5 to 1.5 million. The air supply system capacity allows run times up to five minutes at maximum flow rates. A coolant supply system has been built to deliver mixtures of SFsb6 and air to simulate coolant/mainstream density ratios up to 2. The cascade contains several novel features. A full-perimeter bleed slot upstream of the blades is used to remove the approach boundary layer from all four walls, to improve the degree of two-dimensionality. The exit flow is bounded by two adjustable tailboards that are hinged at the trailing edges and actuated to set the exit flow direction according to the imposed pressure ratio. The boards are perforated and subjected to mass removal near the blades, to minimize the undesirable reflection of shocks and expansion waves. A probe actuator is incorporated that allows continuous positioning of probes in the exhaust stream, in both the streamwise and pitchwise directions. Diagnostic methods include extensive surface pressure taps on the approach and exhaust ducts and on the blade surfaces. The large size permitted as many as 19 taps on the trailing edge itself. Shadowgraph and schlieren are available. A three-prong wake probe has been constructed to simultaneously measure total and static pressures

  10. Performance of Single-Stage Turbine of Mark 25 Torpedo Power Plant with Two Nozzles and Three Rotor-Blade Designs

    NASA Technical Reports Server (NTRS)

    Schum, Harold J.; Whitney, Warren J.

    1949-01-01

    A single-stage modification of the turbine from a Mark 25 torpedo power plant was investigated to determine the performance with two nozzles and three rotor-blade designs. The performance was evaluated in terms of brake, rotor, and blade efficiencies at pressure ratios of 8, 15 (design), and 20. The blade efficiencies with the two nozzles are compared with those obtained with four other nozzles previously investigated with the same three rotor-blade designs. Blade efficiency with the cast nozzle of rectangular cross section (J) was higher than that with the circular reamed nozzle (K) at all speeds and pressure ratios with a rotor having a 0.45-inch 17 degree-inlet-angle blades. The efficiencies for both these nozzles were generally low compared with those of the four other nozzles previously investigated in combination with this rotor. At pressure ratios of 15 and 20, the blade efficiencies with nozzle K and the two rotors with 0.40-inch blades having different inlet angles were higher than with the four other nozzles, but the efficiency with nozzle J was generally low. Increasing the blade inlet angle from 17 degrees to 20 degrees had little effect on turbine performance, whereas changing the blade length from 0.40 to 0.45 inch had a marked effect. Although a slight correlation of efficiency with nozzle size was noted for the rotor with 0.45-inch 17 degree-inlet-angle blades, no such effect was discernible ,for the two rotors with 0.40-inch blades.Losses in the supersonic air stream resulting from the complex flow path in the small air passages are probably a large percentage of the total losses, and apparently the effects of changing nozzle size and shape within the limits investigated are of secondary importance.

  11. The Effect of Blade-Section Thickness Ratio on the Aerodynamic Characteristics of Related Full-Scale Propellers at Mach Numbers up to 0.65

    NASA Technical Reports Server (NTRS)

    Maynard, Julian D; Steinberg, Seymour

    1953-01-01

    The results of an investigation of two 10-foot-diameter, two-blade NACA propellers are presented for a range of blade angles from 20 degrees to 55 degrees at airspeeds up to 500 miles per hour. These results are compared with those from previous investigations of five related NACA propellers in order to evaluate the effects of blade-section thickness ratios on propeller aerodynamic characteristics.

  12. Large, low cost composite wind turbine blades

    NASA Technical Reports Server (NTRS)

    Gewehr, H. W.

    1979-01-01

    A woven roving E-glass tape, having all of its structural fibers oriented across the tape width was used in the manufacture of the spar for a wind turbine blade. Tests of a 150 ft composite blade show that the transverse filament tape is capable of meeting structural design requirements for wind turbine blades. Composite blades can be designed for interchangeability with steel blades in the MOD-1 wind generator system. The design, analysis, fabrication, and testing of the 150 ft blade are discussed.

  13. Influence of rotor blade tip shape on tip vortex shedding - An unsteady, inviscid analysis

    NASA Technical Reports Server (NTRS)

    Maskew, B.

    1980-01-01

    An unsteady potential flow panel method is described based on a time-stepping procedure and using planar quadrilateral panels to represent the surface of thick blades. Each panel has a constant source and doublet distribution and a central control point where an internal Dirichlet boundary condition is applied. The method includes detail paneling around the tip edge and offers the facility of prescribing a tip-edge separation. Preliminary results are shown for four blade tip shapes which are treated as semi-span wings oscillating in pitch about a mean angle of attack of 6 deg. Further work is planned for the wake model before proceeding to higher angles of attack.

  14. Estimation of blade airloads from rotor blade bending moments

    NASA Technical Reports Server (NTRS)

    Bousman, William G.

    1987-01-01

    This paper presents a method for the estimation of blade airloads, based on the measurements of flap bending moments. In this procedure, the blade rotation in vacuum modes is calculated, and the airloads are expressed as an algebraic sum of the mode shapes, modal amplitudes, mass distribution, and frequency properties. The method was validated by comparing the calculated airload distribution with the original wind tunnel measurements which were made using ten modes and twenty measurement stations. Good agreement between the predicted and the measured airloads was found up to 0.90 R, but the agreement degraded towards the blade tip. The method is shown to be quite robust to the type of experimental problems that could be expected to occur in the testing of full-scale and model-scale rotors.

  15. Rapid Aeroelastic Analysis of Blade Flutter in Turbomachines

    NASA Technical Reports Server (NTRS)

    Trudell, J. J.; Mehmed, O.; Stefko, G. L.; Bakhle, M. A.; Reddy, T. S. R.; Montgomery, M.; Verdon, J.

    2006-01-01

    The LINFLUX-AE computer code predicts flutter and forced responses of blades and vanes in turbomachines under subsonic, transonic, and supersonic flow conditions. The code solves the Euler equations of unsteady flow in a blade passage under the assumption that the blades vibrate harmonically at small amplitudes. The steady-state nonlinear Euler equations are solved by a separate program, then equations for unsteady flow components are obtained through linearization around the steady-state solution. A structural-dynamics analysis (see figure) is performed to determine the frequencies and mode shapes of blade vibrations, a preprocessor interpolates mode shapes from the structural-dynamics mesh onto the LINFLUX computational-fluid-dynamics mesh, and an interface code is used to convert the steady-state flow solution to a form required by LINFLUX. Then LINFLUX solves the linearized equations in the frequency domain to calculate the unsteady aerodynamic pressure distribution for a given vibration mode, frequency, and interblade phase angle. A post-processor uses the unsteady pressures to calculate generalized aerodynamic forces, response amplitudes, and eigenvalues (which determine the flutter frequency and damping). In comparison with the TURBO-AE aeroelastic-analysis code, which solves the equations in the time domain, LINFLUX-AE is 6 to 7 times faster.

  16. Blade Tip Rubbing Stress Prediction

    NASA Technical Reports Server (NTRS)

    Davis, Gary A.; Clough, Ray C.

    1991-01-01

    An analytical model was constructed to predict the magnitude of stresses produced by rubbing a turbine blade against its tip seal. This model used a linearized approach to the problem, after a parametric study, found that the nonlinear effects were of insignificant magnitude. The important input parameters to the model were: the arc through which rubbing occurs, the turbine rotor speed, normal force exerted on the blade, and the rubbing coefficient of friction. Since it is not possible to exactly specify some of these parameters, values were entered into the model which bracket likely values. The form of the forcing function was another variable which was impossible to specify precisely, but the assumption of a half-sine wave with a period equal to the duration of the rub was taken as a realistic assumption. The analytical model predicted resonances between harmonics of the forcing function decomposition and known harmonics of the blade. Thus, it seemed probable that blade tip rubbing could be at least a contributor to the blade-cracking phenomenon. A full-scale, full-speed test conducted on the space shuttle main engine high pressure fuel turbopump Whirligig tester was conducted at speeds between 33,000 and 28,000 RPM to confirm analytical predictions.

  17. Hub-mounted actuators for blade pitch collective control

    NASA Technical Reports Server (NTRS)

    Jeffery, Philip A. E. (Inventor); Luecke, Greg R. (Inventor)

    1985-01-01

    Blade collective pitch control is provided for a rotor system by rotary actuators located between adjacent blades. Each actuator is connected to the leading edge of one adjacent blade and the trailing edge of the other adjacent blade.

  18. Spanwise aerodynamic loads on a rotating wind turbine blade

    SciTech Connect

    Butterfield, C.P.; Simms, D.; Musial, W.; Scott, G.

    1990-10-01

    Wind turbine performance and load predictions depend on accurate airfoil performance data. Wind tunnel test data are typically used which accurately describe two-dimensional airfoil performance characteristics. Usually these data are only available for a range of angles of attack from 0 to 15 deg, which excludes the stall characteristics. Airfoils on stall-controlled wind turbines operate in deep stall in medium to high winds. Therefore it is very important to know how the airfoil will perform in these high load conditions. Butterfield et al. have shown that three-dimensional effects and rotation of the blade modify the two-dimensional performance of the airfoil. These effects are modified to different degrees throughout the blade span. The Solar Energy Research Institute (SERI) has conducted a series of tests to measure the spanwise variation of airfoil performance characteristics on a rotating wind turbine blade. Maximum lift coefficients were measured to be 200% greater than wind tunnel results at the 30% span. Stall characteristics were generally modified throughout the span. Lift characteristics were unmodified for low to medium angles of attack. This paper discusses these test results for four spanwise locations. 8 refs., 12 figs.

  19. Coupled aeroelastic oscillations of a turbine blade row in 3D transonic flow

    NASA Astrophysics Data System (ADS)

    Gnesin, Vitaly; Kolodyazhnaya, Lyubov; Rzadkowski, Romuald

    2001-10-01

    This paper presents the mutual time - marching method to predict the aeroelastic stability of an oscillating blade row in 3D transonic flow. The ideal gas flow through a blade row is governed by the time dependent Euler equations in conservative form which are integrated by using the explicit monotonous second order accurate Godunov-Kolgan finite volume scheme and moving hybrid H-O grid. The structure analysis uses the modal approach and 3D finite element dynamic model of blade. The blade movement is assumed as a linear combination of the first modes of blade natural oscillations with the modal coefficients depending on time. To demonstrate the capability and correctness of the method, two experimentally investigated test cases have been selected, in which the blades had performed tuned harmonic bending or torsional vibrations (The 1st and 4th standard configurations of the “Workshop on Aeroelasticity in Turbomachines” by Bolcs and Fransson, 1986). The calculated results of aeroelastic behaviour of the blade row (4th standard configuration), are presented over a wide frequency range under different start regimes of interblade phase angle.

  20. a New Active Control Strategy for Wind-Turbine Blades Under Off-Design Conditions

    NASA Astrophysics Data System (ADS)

    Zhang, Ri-Kui; Wu, Jie-Zhi; Chen, Shi-Yi

    A new active control strategy for wind-turbine blades under off-design conditions has been investigated in this paper. According to our previous work, in comparison with the traditional straight leading-edge blade, a new kind of bionic blades with a sinusoidal leading edge can significantly enhance the turbine's power output at high speed inflows. However, the wavy leading-edge shape is unfavorable under the design operating conditions since an early boundary-layer separation is inevitable for a wind-turbine blade because of the geometric disturbances of the leading-edge tubercles. But for the present active control, the deflect in wavy leading-edge blades can be eliminated by introducing a series of small flat delta wings as the control units, since delta wings can also generate powerful leading-edge vortices. As a preliminary test, our numerical results show that, the shaft-torque fluctuation in the turbine's stall region can be improved from 27.8% for a straight leading-edge blade (no control) to 8.9% for the present active control; and by adjusting the control parameters, the control units nearly have not any negative effect on the blade's shaft torque under the design conditions. We believe that, as an auxiliary tool of the conventional control strategies, the present active control approach may be favorable to generate a more stable and more controllable power output for wind turbines under all operating conditions (even in the yawed inflows).

  1. Structural Analysis and Optimization of a Composite Fan Blade for Future Aircraft Engine

    NASA Technical Reports Server (NTRS)

    Coroneos, Rula M.

    2012-01-01

    This report addresses the structural analysis and optimization of a composite fan blade sized for a large aircraft engine. An existing baseline solid metallic fan blade was used as a starting point to develop a hybrid honeycomb sandwich construction with a polymer matrix composite face sheet and honeycomb aluminum core replacing the original baseline solid metallic fan model made of titanium. The focus of this work is to design the sandwich composite blade with the optimum number of plies for the face sheet that will withstand the combined pressure and centrifugal loads while the constraints are satisfied and the baseline aerodynamic and geometric parameters are maintained. To satisfy the requirements, a sandwich construction for the blade is proposed with composite face sheets and a weak core made of honeycomb aluminum material. For aerodynamic considerations, the thickness of the core is optimized whereas the overall blade thickness is held fixed so as to not alter the original airfoil geometry. Weight is taken as the objective function to be minimized by varying the core thickness of the blade within specified upper and lower bounds. Constraints are imposed on radial displacement limitations and ply failure strength. From the optimum design, the minimum number of plies, which will not fail, is back-calculated. The ply lay-up of the blade is adjusted from the calculated number of plies and final structural analysis is performed. Analyses were carried out by utilizing the OpenMDAO Framework, developed at NASA Glenn Research Center combining optimization with structural assessment.

  2. Use of Blade Lean in Turbomachinery Redesign

    NASA Technical Reports Server (NTRS)

    Moore, John; Moore, Joan G.; Lupi, Alex

    1993-01-01

    Blade lean is used to improve the uniformity of exit flow distributions from turbomachinery blading. In turbines, it has been used to control secondary flows by tailoring blade turning to reduce flow overturning and underturning and to create more uniform loss distributions from hub to shroud. In the present study, the Pump Consortium centrifugal impeller has been redesigned using blade lean. The flow at the exit of the baseline impeller had large blade-to-blade variations, creating a highly unsteady flow for the downstream diffuser. Blade lean is used to redesign the flow to move the high loss fluid from the suction side to the hub, significantly reducing blade-toblade variations at the exit.

  3. Structural Tailoring of SSME Blades (vanes)

    NASA Technical Reports Server (NTRS)

    Rubinstein, R.

    1985-01-01

    The engine blade design optimization program STAEBL (Structural Tailoring of Engine Blades) is available at the NASA Lewis computer facility. The analysis capabilities of this program were extended to typical loading conditions for SSME turbopump blades including thermal and pressure loading. Input files for representative SSME blade designs were developed and sample optimization studies for these blades completed. The structural tailoring program combines a general optimization package and a finite element blade analysis package. The analysis package's capabilities include natural frequency, maximum stress, and forced response computation, and fatigue life and flutter analysis. Optimization is performed using the feasible directions method. The current design is modified by perturbing the design variables so that the design constraints are satisfied while the objective function, such as blade weight, is reduced at the maximum rate. The program's geometric design variables include blade thickness distribution, thickness to chord ratios, and root chord.

  4. Use of blade lean in turbomachinery redesign

    NASA Astrophysics Data System (ADS)

    Moore, John; Moore, Joan G.; Lupi, Alex

    1993-07-01

    Blade lean is used to improve the uniformity of exit flow distributions from turbomachinery blading. In turbines, it has been used to control secondary flows by tailoring blade turning to reduce flow overturning and underturning and to create more uniform loss distributions from hub to shroud. In the present study, the Pump Consortium centrifugal impeller has been redesigned using blade lean. The flow at the exit of the baseline impeller had large blade-to-blade variations, creating a highly unsteady flow for the downstream diffuser. Blade lean is used to redesign the flow to move the high loss fluid from the suction side to the hub, significantly reducing blade-toblade variations at the exit.

  5. Smoother Turbine Blades Resist Thermal Shock Better

    NASA Technical Reports Server (NTRS)

    Czerniak, Paul; Longenecker, Kent; Paulus, Don; Ullman, Zane

    1991-01-01

    Surface treatment increases resistance of turbine blades to low-cycle fatigue. Smoothing removes small flaws where cracks start. Intended for blades in turbines subject to thermal shock of rapid starting. No recrystallization occurs at rocket-turbine operating temperatures.

  6. Spring-Blade Impact Tester

    NASA Technical Reports Server (NTRS)

    Holmes, Alan M.; Champagne, James W.

    1989-01-01

    Record of energy relationships retrieved from compact, portable tester. Spring-blade impact tester developed to support evaluation of tolerance to damage of struts under consideration for use in Space Station. Approach offers potential for determining damage as function of change in relationship between applied and absorbed energies as applied energy successively increased with each impact. Impactor strikes specimen at moment of maximum kinetic energy after spring blades released from cocked position. Concept also provides potential for measuring behavior during impact, and energy relationships retrievable from oscilloscope traces of impact.

  7. Blade for a gas turbine

    DOEpatents

    Liang, George

    2010-10-26

    A blade is provided for a gas turbine. The blade comprises a main body comprising a cooling fluid entrance channel; a cooling fluid collector in communication with the cooling fluid entrance channel; a plurality of side channels extending through an outer wall of the main body and communicating with the cooling fluid collector and a cooling fluid cavity; a cooling fluid exit channel communicating with the cooling fluid cavity; and a plurality of exit bores extending from the cooling fluid exit channel through the main body outer wall.

  8. Computational studies of flow through cross flow fans - effect of blade geometry

    NASA Astrophysics Data System (ADS)

    Govardhan, M.; Sampat, D. Lakshmana

    2005-09-01

    This present paper describes three dimensional computational analysis of complex internal flow in a cross flow fan. A commercial computational fluid dynamics (CFD) software code CFX was used for the computation. RNG k-ɛ two equation turbulence model was used to simulate the model with unstructured mesh. Sliding mesh interface was used at the interface between the rotating and stationary domains to capture the unsteady interactions. An accurate assessment of the present investigation is made by comparing various parameters with the available experimental data. Three impeller geometries with different blade angles and radius ratio are used in the present study. Maximum energy transfer through the impeller takes place in the region where the flow follows the blade curvature. Radial velocity is not uniform through blade channels. Some blades work in turbine mode at very low flow coefficients. Static pressure is always negative in and around the impeller region.

  9. The boundary layer on compressor cascade blades

    NASA Technical Reports Server (NTRS)

    Deutsch, S.

    1981-01-01

    Some redesign of the cascade facility was necessary in order to incoporate the requirements of the LDA system into the design. Of particular importance was the intended use of a combination of suction upstream of the blade pack with diverging pack walls, as opposed to blade pack suction alone, for spanwise dimensionality control. An ARL blade was used to redo some tests using this arrangement. Preliminary testing and boundary layer measurements began on the double circular arc blades.

  10. Structural tailoring of engine blades (STAEBL)

    NASA Technical Reports Server (NTRS)

    Platt, C. E.; Pratt, T. K.; Brown, K. W.

    1982-01-01

    A mathematical optimization procedure was developed for the structural tailoring of engine blades and was used to structurally tailor two engine fan blades constructed of composite materials without midspan shrouds. The first was a solid blade made from superhybrid composites, and the second was a hollow blade with metal matrix composite inlays. Three major computerized functions were needed to complete the procedure: approximate analysis with the established input variables, optimization of an objective function, and refined analysis for design verification.

  11. Investigation of the Performance of an Axial-Flow-Pump Stage Designed by the Blade-Element Theory: Blade-Element Data

    NASA Technical Reports Server (NTRS)

    Crouse, James E.; Soltis, Richard F.; Montgomery, John C.

    1961-01-01

    An axial-flow-pump stage was designed by utilizing blade-element methods in conjunction with axial-flow-compressor blade-element theory. This report presents the blade-element data of the pump stage in both the noncavitating and cavitating conditions. The noncavitating blade- element performance is compared with design rules. The results indicated that some modification of the compressor design equations for computing minimum-loss incidence and deviation angles may be necessary for application to an axial-flow-pump design. Minimum values of observed rotor loss were slightly lower than anticipated from compressor results. At the design flow coefficient the rotor-blade elements were not operating at the reference incidence angles, and the experimental efficiency was lower than the design value. The observed head rise was very close to the design. An attempt was made to estimate the potential of this rotor by using the minimum measured values of loss coefficient and observed energy input at the design flow. Performance of the pump at a suction specific speed of approximately 13,000 (cavitation number k approximately equals 0.12) showed only a slight dropoff in performance in the cavitation inception region from the noncavitating results. The observed performance at a suction specific speed of approximately 16,000 (k approximately equals 0.09) is also presented for comparison.

  12. Thermal and Structural Analysis of a Hollow Core Space Shuttle Main Engine (SSME) Turbine Blade

    NASA Technical Reports Server (NTRS)

    Abdul-Aziz, Ali; Kalluri, Sreeramesh; McGaw, Michael A.

    1995-01-01

    The influence of primary and secondary orientations on the elastic response of a hollow core, (001)-oriented nickel base single-crystal superalloy turbine blade, was investigated under combined thermal and mechanical conditions. Finite element techniques is employed through MARC finite element code to conduct the analyses on a hollow core SSME turbine blade made out of PWA 1480 single crystal material. Primary orientation of the single crystal superalloy was varied in increments of 2 deg, from 0 to 10 deg, from the (001) direction. Two secondary orientations (0 and 45 deg) were considered with respect to the global coordinate system, as the primary orientation angle was varied. The stresses developed within the single crystal blade were determined for different orientations of the blade. The influence of angular offsets such as the single crystal's primary and secondary orientations and the loading conditions on the elastic stress response of the PWA 1480 hollow blade are summarized. The influence of he primary orientation angle, when constrained between the bounds considered, was not found to be as significant as the influence of the secondary orientation angle.

  13. A combined piezoelectric composite actuator and its application to wing/blade tips

    NASA Astrophysics Data System (ADS)

    Ha, Kwangtae

    A novel combined piezoelectric-composite actuator configuration is proposed and analytically modeled in this work. The actuator is a low complexity, active compliant mechanism obtained by coupling a modified star cross sectional configuration composite beam with a helicoidal bimorph piezoelectric actuator coiled around it. This novel actuator is a good candidate as a hinge tension-torsion bar actuator for a helicopter rotor blade flap or blade tip and mirror rotational positioning. In the wing tip case, the tip deflection angle is different only according to the aerodynamic moment depending on the hinge position of the actuator along the chord and applied voltage because there is no centrifugal force. For an active blade tip subject to incompressible flow and 2D quasi steady airloads, its twist angle is related not only to aerodynamic moment and applied voltage but also to coupling terms, such as the trapeze effect and the tennis racquet effect. Results show the benefit of hinge position aft of the aerodynamic center, such that the blade tip response is amplified by airloads. Contrary to this effect, results also show that the centrifugal effects and inertial effect cause an amplitude reduction in the response. Summation of these effects determines the overall blade tip response. The results for a certain hinge position of Xh=1.5% chord aft of the quarter chord point proves that the tip deflection target design range of beta ∈ [-2,+2] can be achieved for all pitch angle configurations chosen.

  14. Comparison of model helicopter rotor primary and secondary blade/vortex interaction blade slap

    NASA Astrophysics Data System (ADS)

    Hubbard, J. E., Jr.; Leighton, K. P.

    1984-05-01

    A study of the relative importance of blade/vortex interactions which occur on the retreating side of a model helicopter rotor disk is described. Some of the salient characteristics of this phenomenon are presented and discussed. It is shown that the resulting Secondary blade slap may be of equal or greater intensity than the advancing side (Primary) blade slap. Instrumented model helicopter rotor data is presented which reveals the nature of the retreating blade/vortex interaction. The importance of Secondary blade slap as it applies to predictive techniques or approaches is discussed. When Secondary blade slap occurs it acts to enlarge the window of operating conditions for which blade slap exists.

  15. A comparison of model helicopter rotor Primary and Secondary blade/vortex interaction blade slap

    NASA Technical Reports Server (NTRS)

    Hubbard, J. E., Jr.; Leighton, K. P.

    1983-01-01

    A study of the relative importance of blade/vortex interactions which occur on the retreating side of a model helicopter rotor disk is described. Some of the salient characteristics of this phenomenon are presented and discussed. It is shown that the resulting Secondary blade slap may be of equal or greater intensity than the advancing side (Primary) blade slap. Instrumented model helicopter rotor data is presented which reveals the nature of the retreating blade/vortex interaction. The importance of Secondary blade slap as it applies to predictive techniques or approaches is discussed. When Secondary blade slap occurs it acts to enlarge the window of operating conditions for which blade slap exists.

  16. Experimental investigation of effects of blade tip geometry on loads and performance for an articulated rotor system

    NASA Technical Reports Server (NTRS)

    Weller, W. H.

    1979-01-01

    Wind-tunnel tests of an aeroelastically designed helicopter rotor model were carried out to determine the effects on dynamic response and aerodynamic performance of varying the design of the outboard 8 percent of the blade lengths. Four different blade tip geometries or shapes having different amounts of planform sweep, thickness and chordwise taper, and anhedral angle were studied. Each configuration was tested at several shaft angles of attack for advance ratios of 0.20, 0.30, 0.35, and 0.40. For each combination of shaft angle and advance ratio, rotor lift was varied over a wide range to include high lift conditions.

  17. Perturbation solutions for transonic flow on the blade-to-blade surface of compressor blade rows

    NASA Technical Reports Server (NTRS)

    Stahara, S. S.; Chaussee, D. S.; Spreiter, J. R.

    1978-01-01

    A preliminary investigation was conducted to establish the theoretical basis of perturbation techniques with the objective of minimizing computational requirements associated with parametric studies of transonic flows in turbomachines. The theoretical analysis involved the development of perturbation methods for determining first order changes in the flow solution due to variations of one or more geometrical or flow parameters. The formulation is primarily directed toward transonic flows on the blade to blade surface of a single blade row compressor. Two different perturbation approaches were identified and studied. Applications and results of these methods for various perturbations are presented for selected two dimensional transonic cascade flows to illustrate the advantages and disadvantages of each technique. Additionally, it was found that, for flows with shock waves, proper account of shock displacement was crucial.

  18. Ergonomic evaluation of the Apple Adjustable Keyboard

    SciTech Connect

    Tittiranonda, P.; Burastero, S.; Shih, M.; Rempel, D.

    1994-05-01

    This study presents an evaluation of the Apple Adjustable Keyboard based on subjective preference and observed joint angles during typing. Thirty five keyboard users were asked to use the Apple adjustable keyboard for 7--14 days and rate the various characteristics of the keyboard. Our findings suggest that the most preferred opening angles range from 11--20{degree}. The mean ulnar deviation on the Apple Adjustable keyboard is 11{degree}, compared to 16{degree} on the standard keyboard. The mean extension was decreased from 24{degree} to 16{degree} when using the adjustable keyboard. When asked to subjectively rate the adjustable keyboard in comparison to the standard, the average subject felt that the Apple Adjustable Keyboard was more comfortable and easier to use than the standard flat keyboard.

  19. Computer Program Aids Design Of Impeller Blades

    NASA Technical Reports Server (NTRS)

    Chen, Wei-Chung; Galazin, John V.

    1992-01-01

    Impeller blades for centrifugal turbopumps designed quickly with help of computer program. Generates blade contours and continually subjects them to evaluation. Checks physical parameters to ensure they are compatible with required performance and recycles design if criteria not met. Program written for centrifugal turbomachinery, also adapted to such axial pump components as inducer blades and stator vanes.

  20. Fiber composite fan blade impact improvement program

    NASA Technical Reports Server (NTRS)

    Oller, T. L.

    1976-01-01

    The results of a 20-month program, designed to investigate parameters which effect the foreign object damage resulting from ingestion of birds into fan blades are described. Work performed on this program included the design, fabrication, and impact testing of QCSEE fan blades to demonstrate improvement in resistance relative to existing blades and also the design and demonstration of a pin root attachment concept.

  1. Forward sweep, low noise rotor blade

    NASA Technical Reports Server (NTRS)

    Brooks, Thomas F. (Inventor)

    1996-01-01

    A forward-swept, low-noise rotor blade includes an inboard section, an aft-swept section and a forward-swept outboard section. The rotor blade reduces the noise of rotorcraft, including both standard helicopters and advanced systems such as tiltrotors. The primary noise reduction feature is the forward sweep of the planform over a large portion of the outer blade radius. The rotor blade also includes an aft-swept section. The purpose of the aft-swept region is to provide a partial balance to pitching moments produced by the outboard forward-swept portion of the blade. The rotor blade has a constant chord width; or has a chord width which decreases linearly along the entire blade span; or combines constant and decreasing chord widths, wherein the blade is of constant chord width from the blade root to a certain location on the rotor blade, then decreases linearly to the blade tip thereafter. The noise source showing maximum noise reduction is blade-vortex interaction (BVI) noise. Also reduced are thickness, noise, high speed impulsive noise, cabin vibration and loading noise.

  2. Dynamic response of active twist rotor blades

    NASA Astrophysics Data System (ADS)

    Cesnik, Carlos E. S.; Shin, Sang Joon; Wilbur, Matthew L.

    2001-02-01

    Dynamic characteristics of active twist rotor (ATR) blades are investigated analytically and experimentally in this paper. The ATR system is intended for vibration and potentially for noise reductions in helicopters through individual blade control. An aeroelastic model is developed to identify frequency response characteristics of the ATR blade with integral, generally anisotropic, strain actuators embedded in its composite construction. An ATR prototype blade was designed and manufactured to experimentally study the vibration reduction capabilities of such systems. Several bench and hover tests were conducted and those results are presented and discussed here. Selected results on sensitivity of the ATR system to collective setting (i.e. blade loading), blade rpm (i.e. centrifugal force and blade station velocity), and media density (i.e. altitude) are presented. They indicated that the twist actuation authority of the ATR blade is independent of the collective setting up to approximately 10P, and dependent on rotational speed and altitude near the torsional resonance frequency due to its dependency on the aerodynamic damping. The proposed model captures very well the physics and sensitivities to selected test parameters of the ATR system. The numerical result of the blade torsional loads show an average error of 20% in magnitude and virtually no difference in phase for the blade frequency response. Overall, the active blade model is in very good agreement with the experiments and can be used to analyze and design future active helicopter blade systems.

  3. On the Physics of Flow Separation Along a Low Pressure Turbine Blade Under Unsteady Flow Conditions

    NASA Technical Reports Server (NTRS)

    Schobeiri, Meinhard T.; Ozturk, Burak; Ashpis, David E.

    2003-01-01

    The present study, which is the first of a series of investigations dealing with specific issues of low pressure turbine (LPT) boundary layer aerodynamics, is aimed at providing detailed unsteady boundary flow information to understand the underlying physics of the inception, onset, and extent of the separation zone. A detailed experimental study on the behavior of the separation zone on the suction surface of a highly loaded LPT-blade under periodic unsteady wake flow is presented. Experimental investigations were performed at Texas A&M Turbomachinery Performance and Flow Research Laboratory using a large-scale unsteady turbine cascade research facility with an integrated wake generator and test section unit. To account for a high flow deflection of LPT-cascades at design and off-design operating points, the entire wake generator and test section unit including the traversing system is designed to allow a precise angle adjustment of the cascade relative to the incoming flow. This is done by a hydraulic platform, which simultaneously lifts and rotates the wake generator and test section unit. The unit is then attached to the tunnel exit nozzle with an angular accuracy of better than 0.05 , which is measured electronically. Utilizing a Reynolds number of 110,000 based on the blade suction surface length and the exit velocity, one steady and two different unsteady inlet flowconditions with the corresponding passing frequencies, wake velocities and turbulence intensities are investigated using hot-wire anemometry. In addition to the unsteady boundary layer measurements, blade surface pressure measurements were performed at Re=50,000, 75,000, 100,000, and 125,000 at one steady and two periodic unsteady inlet flow conditions. Detailed unsteady boundary layer measurement identifies the onset and extent of the separation zone as well as its behavior under unsteady wake flow. The results presented in ensemble-averaged and contour plot forms contribute to understanding the

  4. On the Physics of Flow Separation Along a Low Pressure Turbine Blade Under Unsteady Flow Conditions

    NASA Technical Reports Server (NTRS)

    Schobeiri, Meinhard T.; Ozturk, Burak; Ashpis, David E.

    2005-01-01

    The present study, which is the first of a series of investigations dealing with specific issues of low pressure turbine (LPT) boundary layer aerodynamics, is aimed at providing detailed unsteady boundary flow information to understand the underlying physics of the inception, onset, and extent of the separation zone. A detailed experimental study on the behavior of the separation zone on the suction surface of a highly loaded LPT-blade under periodic unsteady wake flow is presented. Experimental investigations were performed at Texas A&M Turbomachinery Performance and Flow Research Laboratory using a large-scale unsteady turbine cascade research facility with an integrated wake generator and test section unit. To account for a high flow deflection of LPT-cascades at design and off-design operating points, the entire wake generator and test section unit including the traversing system is designed to allow a precise angle adjustment of the cascade relative to the incoming flow. This is done by a hydraulic platform, which simultaneously lifts and rotates the wake generator and test section unit. The unit is then attached to the tunnel exit nozzle with an angular accuracy of better than 0.05 , which is measured electronically. Utilizing a Reynolds number of 110,000 based on the blade suction surface length and the exit velocity, one steady and two different unsteady inlet flow conditions with the corresponding passing frequencies, wake velocities and turbulence intensities are investigated using hot-wire anemometry. In addition to the unsteady boundary layer measurements, blade surface pressure measurements were performed at Re=50,000, 75,000, 100,000, and 125,000 at one steady and two periodic unsteady inlet flow conditions. Detailed unsteady boundary layer measurement identifies the onset and extent of the separation zone as well as its behavior under unsteady wake flow. The results presented in ensemble-averaged and contour plot forms contribute to understanding the

  5. A parametric study of transonic blade-vortex interaction noise

    NASA Technical Reports Server (NTRS)

    Lyrintzis, A. S.

    1991-01-01

    Several parameters of transonic blade-vortex interactions (BVI) are being studied and some ideas for noise reduction are introduced and tested using numerical simulation. The model used is the two-dimensional high frequency transonic small disturbance equation with regions of distributed vorticity (VTRAN2 code). The far-field noise signals are obtained by using the Kirchhoff method with extends the numerical 2-D near-field aerodynamic results to the linear acoustic 3-D far-field. The BVI noise mechanisms are explained and the effects of vortex type and strength, and angle of attack are studied. Particularly, airfoil shape modifications which lead to noise reduction are investigated. The results presented are expected to be helpful for better understanding of the nature of the BVI noise and better blade design.

  6. In flight measurement of steady and unsteady blade surface pressure of a single rotation large scale advanced prop-fan installed on the PTA aircraft

    NASA Technical Reports Server (NTRS)

    Parzych, D.; Boyd, L.; Meissner, W.; Wyrostek, A.

    1991-01-01

    An experiment was performed by Hamilton Standard, Division of United Technologies Corporation, under contract by LeRC, to measure the blade surface pressure of a large scale, 8 blade model prop-fan in flight. The test bed was the Gulfstream 2 Prop-Fan Test Assessment (PTA) aircraft. The objective of the test was to measure the steady and periodic blade surface pressure resulting from three different Prop-Fan air inflow angles at various takeoff and cruise conditions. The inflow angles were obtained by varying the nacelle tilt angles, which ranged from -3 to +2 degrees. A range of power loadings, tip speeds, and altitudes were tested at each nacelle tilt angle over the flight Mach number range of 0.30 to 0.80. Unsteady blade pressure data tabulated as Fourier coefficients for the first 35 harmonics of shaft rotational frequency and the steady (non-varying) pressure component are presented.

  7. The role of free stream turbulence and blade surface conditions on the aerodynamic performance of wind turbine blades

    NASA Astrophysics Data System (ADS)

    Maldonado, Victor Hugo

    with a 24-grit abrasive sheet. The role of turbulence and surface roughness on the aerodynamic performance of the wind turbine blade was investigated utilizing the following experimental techniques: (i) static pressure measurements around the blade, (ii) constant temperature anemometry (CTA) hot-wire and pitottube measurements of the velocity deficit at the wake, and (iii) two-dimensional particle image velocimetry (2-D PIV) measurements of the mean global flow. Results indicate that turbulence significantly increases the blade's lift coefficient for moderate to post-stall angles of attack (where the range tested was from zero to 18 degrees). This was accompanied without an increase in the drag coefficient for angles of attack below 14 degrees (prior to stall) and a significant reduction in drag for post-stall angles of attack at 16 and 18 degrees. This resulted in considerable increases to the aerodynamic efficiency of the blade, as quantified by the lift to drag ratio, L/D for all angles of attack except zero degrees. Conversely, surface roughness had a detrimental effect on the aerodynamic performance, as verified by 2-D PIV measurements of the mean flow which indicates that surface roughness promotes flow separation. Vortex generators (which are a form of passive flow control and sometimes utilized in wind turbine blades to mitigate the adverse effects of surface roughness) were demonstrated to be very effective in restoring aerodynamic performance. There was a significant increase in the lift coefficient of the blade (while marginally reducing the drag coefficient) thereby increasing the L/D ratio drastically from 1.076 to 2.791 at 18 degrees angle of attack. Finally, earlier work focused on the feasibility of synthetic jets (active flow control) to improve the aerodynamic and aeroelastic performance of wind turbine blades without free stream turbulence or surface roughness. Wind turbine models (including S809 airfoil-based) demonstrated a re-attachment of the

  8. Wind-Tunnel Evaluation of the Effect of Blade Nonstructural Mass Distribution on Helicopter Fixed-System Loads

    NASA Technical Reports Server (NTRS)

    Wilbur, Matthew L.; Yeager, William T., Jr.; Singleton, Jeffrey D.; Mirick, Paul H.; Wilkie, W. Keats

    1998-01-01

    This report provides data obtained during a wind-tunnel test conducted to investigate parametrically the effect of blade nonstructural mass on helicopter fixed-system vibratory loads. The data were obtained with aeroelastically scaled model rotor blades that allowed for the addition of concentrated nonstructural masses at multiple locations along the blade radius. Testing was conducted for advance ratios ranging from 0.10 to 0.35 for 10 blade-mass configurations. Three thrust levels were obtained at representative full-scale shaft angles for each blade-mass configuration. This report provides the fixed-system forces and moments measured during testing. The comprehensive database obtained is well-suited for use in correlation and development of advanced rotorcraft analyses.

  9. Twistable mold for helicopter blades

    NASA Technical Reports Server (NTRS)

    Carter, E. S.; Kiely, E. F.

    1972-01-01

    Design is described of mold for fabrication of blades composed of sets of aerodynamic shells having same airfoil section characteristics but different distributions. Mold consists of opposing stacks of thin templates held together by long bolts. When bolts are loosened, templates can be set at different positions with respect to each other and then locked in place.

  10. Design procedures for compressor blades

    NASA Technical Reports Server (NTRS)

    Starken, H.

    1983-01-01

    The conventional methods for the design of the blades in the case of axial turbomachines are considered, taking into account difficulties concerning the determination of optimal blade profiles. These difficulties have been partly overcome as a consequence of the introduction of new numerical methods during the last few years. It is pointed out that, in the case of the subsonic range, a new procedure is now available for the determination of the form of blade profile on the basis of a given velocity distribution on the profile surface. The search for a profile form with favorable characteristics is consequently transformed into a search for a favorable velocity or pressure distribution on the blade. The distribution of velocities depends to a large degree on the characteristics of the profile boundary layers. The considered concept is not new. However, its practical implementation has only recently become possible. The employment of the new design procedure is illustrated with the aid of an example involving a concrete design problem.

  11. Photo Surfing in Blade Runner

    ERIC Educational Resources Information Center

    Ohler, Jason

    2005-01-01

    This month's "Mining Movies" looks at Blade Runner, Ridley Scott's film set in the year 2019. It is a sad time for Earth, which is in the midst of environmental degradation so severe that other planets are being prepared for colonization. The main source of labor for this preparation work are "replicants," organic robots that look and behave like…

  12. Experimental and numerical study of the British Experimental Rotor Programme blade

    NASA Technical Reports Server (NTRS)

    Brocklehurst, Alan; Duque, Earl P. N.

    1990-01-01

    Wind-tunnel tests on the British Experimental Rotor Programme (BERP) tip are described, and the results are compared with computational fluid dynamics (CFD) results. The test model was molded using the Lynx-BERP blade tooling to provide a semispan, cantilever wing comprising the outboard 30 percent of the rotor blade. The tests included both surface-pressure measurements and flow visualization to obtain detailed information of the flow over the BERP tip for a range of angles of attack. It was observed that, outboard of the notch, favorable pressure gradients exist which ensure attached flow, and that the tip vortex also remains stable to large angles of attack. On the rotor, these features yield a very gradual break in control loads when the retreating-blade limit is eventually reached. Computational and experimental results were generally found to be in good agreement.

  13. Flow separation on wind turbines blades

    NASA Astrophysics Data System (ADS)

    Corten, G. P.

    2001-01-01

    In the year 2000, 15GW of wind power was installed throughout the world, producing 100PJ of energy annually. This contributes to the total electricity demand by only 0.2%. Both the installed power and the generated energy are increasing by 30% per year world-wide. If the airflow over wind turbine blades could be controlled fully, the generation efficiency and thus the energy production would increase by 9%. Power Control To avoid damage to wind turbines, they are cut out above 10 Beaufort (25 m/s) on the wind speed scale. A turbine could be designed in such a way that it converts as much power as possible in all wind speeds, but then it would have to be to heavy. The high costs of such a design would not be compensated by the extra production in high winds, since such winds are rare. Therefore turbines usually reach maximum power at a much lower wind speed: the rated wind speed, which occurs at about 6 Beaufort (12.5 m/s). Above this rated speed, the power intake is kept constant by a control mechanism. Two different mechanisms are commonly used. Active pitch control, where the blades pitch to vane if the turbine maximum is exceeded or, passive stall control, where the power control is an implicit property of the rotor. Stall Control The flow over airfoils is called "attached" when it flows over the surface from the leading edge to the trailing edge. However, when the angle of attack of the flow exceeds a certain critical angle, the flow does not reach the trailing edge, but leaves the surface at the separation line. Beyond this line the flow direction is reversed, i.e. it flows from the trailing edge backward to the separation line. A blade section extracts much less energy from the flow when it separates. This property is used for stall control. Stall controlled rotors always operate at a constant rotation speed. The angle of attack of the flow incident to the blades is determined by the blade speed and the wind speed. Since the latter is variable, it determines

  14. Investigation of the NACA 4-(5)(08)-03 and NACA 4-(10)(08)-03 Two-Blade Propellers at Forward Mach Numbers to 0.725 to Determine the Effects of Camber and Compressibility on Performance

    NASA Technical Reports Server (NTRS)

    Delano, James B

    1951-01-01

    As part of a general investigation of propellers at high forward speeds, tests of two-blade propellers having the NACA 4-(5)(08)-03 and NACA 4-(10)(08)-03 blade designs were made in the Langley 8-foot high-speed tunnel through a range of blade angle from 20 degrees to 60 degrees for forward Mach numbers from 0.165 to 0.70 to determine the effect of camber and compressibility on propeller characteristics. Results previously reported for similar tests of a two-blade propeller having the NACA 4-(3)(08)-03 blade design are included for comparison.

  15. Advanced turbofan blade refurbishment technique

    SciTech Connect

    Roberts, W.B.

    1995-10-01

    The purpose of the work reported here is to investigate whether the lessons learned from the work of Suder et al. can be used to reduce the in-service performance deterioration of a fan on a high bypass ratio turbofan engine. To this end, a back-to-back test was done on the fan of an RB211-22B engine with the cooperation of Delta Airlines. The fan and engine were first overhauled per normal airline practice and cell-tested to establish that the engine performance met flight acceptance standards. This test, which the engine passed, also established a performance baseline for the overhauled engine. At this point the fan blade leading edge had not been filed or scraped and the blade surfaces had not been polished because the leading edge damage and blade surface roughness fell within the acceptable limits specified by the manufacturer for normal overhaul practice. After the cell test, the fan was removed from the engine and sent to Sermatech International where the following additional operations were performed: (1) the blade surfaces were polished to a finish of 20 rms {micro}in; (2) leading edge roughness due to particle impact damage was removed and the leading edge was polished to a finish of 20 rms {micro}in; (3) the leading edge shape was rounded and the leading edge thickness was reduced over the first 5--10% of chord. Test results indicated a 0.7% drop in thrust specific fuel consumption (lb fuel/lb thrust/hr) relative to the baseline engine after the enhanced fan overhaul. Based on the results of Suder et al. (1995) it appears that 70--80% of this performance gain is due to the thin smooth leading edge and the remainder to the highly polished finish of the blade.

  16. Wind tunnel tests of a blade subjected to midchord torsional oscillation at high subsonic stall flutter conditions

    NASA Technical Reports Server (NTRS)

    Boldman, D. R.; Buggele, A. E.

    1978-01-01

    A mechanical drive system for oscillating blades in a wind tunnel at frequencies up to 767 hertz and amplitudes of + or - 1.2 deg is described. High-speed motion pictures of schlieren images of the flow over a double-circular arc blade oscillating in harmonic motion about the midchord revealed extensive shock patterns at a nominal free stream Mach number of 0.7, a mean angle of attack of 4 deg, and reduced frequency of about 0.7. A phase lag resulting from the slow response of the flow to the motion of the blade increased with increasing reduced frequency. This phase lag, based on the difference between the time the blade attained its maximum angle of attack and the time required for the normal shock to reach its extreme downstream position, was nominally 100 deg at the above conditions.

  17. Recent developments in turbine blade internal cooling.

    PubMed

    Han, J C; Dutta, S

    2001-05-01

    This paper focuses on turbine blade internal cooling. Internal cooling is achieved by passing the coolant through several rib-enhanced serpentine passages inside the blade and extracting the heat from the outside of the blades. Both jet impingement and pin-fin-cooling are also used as a method of internal cooling. In the past number of years there has been considerable progress in turbine blade internal cooling research and this paper is limited to reviewing a few selected publications to reflect recent developments in turbine blade internal cooling. PMID:11460626

  18. Turbine blade tip gap reduction system

    DOEpatents

    Diakunchak, Ihor S.

    2012-09-11

    A turbine blade sealing system for reducing a gap between a tip of a turbine blade and a stationary shroud of a turbine engine. The sealing system includes a plurality of flexible seal strips extending from a pressure side of a turbine blade generally orthogonal to the turbine blade. During operation of the turbine engine, the flexible seal strips flex radially outward extending towards the stationary shroud of the turbine engine, thereby reducing the leakage of air past the turbine blades and increasing the efficiency of the turbine engine.

  19. Design and Analysis of an Axial Bypass Compressor Blade in a Supercritical CO2 Gas Turbine

    NASA Astrophysics Data System (ADS)

    Ishizuka, Takao; Muto, Yasushi; Aritomi, Masanori; Tsuzuki, Nobuyoshi; Kikura, Hiroshige

    A supercritical carbon dioxide gas turbine can generate power at a high cycle thermal efficiency, even at modest temperatures of 500-550°C. Consequently, a more reliable and economically advantageous power generation system is achieved by coupling with a Na-cooled fast reactor. This paper mainly describes the bypass compressor (a key component) design and thermal hydraulic analysis using CFD (with FLUENT code). Fluid conditions of the bypass compressor are determined by the cycle calculation of this system. Aerodynamic design was conducted using the loss model described by Cohen et al., which enables the use of several stages while providing total adiabatic efficiency of 21 and 87%, respectivly. Blade shapes were prepared based on flow angles and chord length obtained for the aerodynamic design. In the CFD analysis, the calculated value of the mass flow rate for each stage was adjusted to that of the design. The value of the design outlet pressure was reached at stage No. 16, which is fewer stages than that for design, No. 21. The difference between these stage numbers is attributed to the three-dimensional effect in design. If these effects are eliminated, then the design calculation yields an almost identical number of stages. Therefore, it was concluded that the existing design method is applicable to the supercritical CO2 bypass compressor. Furthermore, CFD analysis appears to be an effective aerodynamic design tool, but these conclusions should be verified experimentally.

  20. Using stream surfaces for blade design

    SciTech Connect

    Miller, P.L. IV; Oliver, J.H.; Miller, D.P.; Tweedt, D.L.

    1997-04-01

    A wide variety of machines with rotating components incorporate blades for imparting energy to, or extracting it from, various fluid streams. Examples include turbines, pumps, compressors, fans, and propellers. In all of these applications, the blade design is critical for achieving optimal performance. Because the underlying function of a blade is to smoothly change the velocity of fluid flow, the blade is generally comprised of parametric sculptured surface models. The complex interaction between the fluid mechanics (i.e., machine performance) and the blade geometry is of fundamental importance in blade design. A new, interactive program offers parameters that are familiar to the designer of turbomachinery blades while it produces a precise and portable nonuniform rational B-spline (NURBS) surface model.

  1. Flutter performance of bend-twist coupled large-scale wind turbine blades

    NASA Astrophysics Data System (ADS)

    Hayat, Khazar; de Lecea, Alvaro Gorostidi Martinez; Moriones, Carlos Donazar; Ha, Sung Kyu

    2016-05-01

    The bend-twist coupling (BTC) is proven to be effective in mitigating the fatigue loads for large-scale wind turbine blades, but at the same time it may cause the risk of flutter instability. The BTC is defined as a feature of twisting of the blade induced by the primary bending deformation. In the classical flutter, the BTC arises from the aerodynamic loads changing with the angle of attack. In this study, the effects of the structural BTC on the flutter are investigated by considering the layup unbalances (ply angle, material and thickness of the composite laminates) in the NREL 5-MW wind turbine rotor blade of glass fiber/epoxy [02/+45/-45]S laminates. It is numerically shown that the flutter speed may decrease by about 5 percent with unbalanced ply-angle only (one side angle, from 45° to 25°). It was then demonstrated that the flutter performance of the wind turbine blade can be increased by using lighter and stiffer carbon fibers which ensures the higher structural BTC at the same time.

  2. Aerodynamics of Rotating-wing Aircraft with Blade-pitch Control

    NASA Technical Reports Server (NTRS)

    Pfluger, A

    1940-01-01

    In the present report, with the aid of the usual computation methods, a rotor is investigated the pitch of whose blades is capable of being controlled in such a manner that it varies linearly with the flapping angle. To test the effect of this linkage on the aircraft performance, the theory is applied to an illustrative example.

  3. The Effect of Rotor Blade Speed to the Best Efficiency Point of Single Stage Axial Flow Compressor

    NASA Astrophysics Data System (ADS)

    Sukri, Mohamad Firdaus; Wasbari, Faizil; Mat, Shafizal

    2010-06-01

    The best efficiency point is ideal operational point for any turbomachinery. Selections of turbomachines in industry such as pump, turbine, compressor, etc are basically based on their operating point. The best efficiency point is a point at the highest efficiency. Therefore, turbomachines with nearest operating point to best efficiency point will be chosen due to higher efficiency thus produce great reduction in cost saving. Different speed of rotor blade will cause effect to the best efficiency point, as well as different in rotor and stator blade angle. If angle of rotor and stator blade constant while speed of rotor blade increased, the net head produced by the compressor will also increased. Thus, it will increase the brake horse power and fluid horse power. Although the efficiency of the compressor increases if fluid horse power increased, the increasing in brake horse power will produce lower efficiency. In this paper, the effect of rotor blade speed on best efficiency point of an axial flow compressor will be investigated and discussed. Through this paper, the highest efficiency is only 73 %, achieved at rotor blade speed of 750 rpm with net head of 9.4 mmWG, and air volumetric flow rate of 0.56m3/s. For higher net head, the rotor blade speed must be increased, but the efficiency will decrease simultaneously. The type of compressor used in this research is single stage axial flow compressor; model Dixson FM36, manufactured by Dixson FA Engineering Sdn. Bhd.

  4. Prediction of blade vortex interaction noise from measured blade pressure

    NASA Technical Reports Server (NTRS)

    Nakamura, Y.

    1981-01-01

    The impulsive nature of noise due to the interaction of a rotor blade with a tip vortex is studied. The time signature of this noise is calculated theoretically based on the measured blade surface pressure fluctuation of an operational load survey rotor in slow descending flight and is compared with the simultaneous microphone measurement. Particularly, the physical understanding of the characteristic features of a waveform is extensively studied in order to understand the generating mechanism and to identify the important parameters. The interaction trajectory of a tip vortex on an acoustic planform is shown to be a very important parameter for the impulsive shape of the noise. The unsteady nature of the pressure distribution at the very leading edge is also important to the pulse shape. The theoretical model using noncompact linear acoustics predicts the general shape of interaction impulse pretty well except for peak amplitude which requires more continuous pressure information along the span at the leading edge.

  5. Aeroelastic dynamics of mistuned blade assemblies with closely spaced blade modes

    NASA Technical Reports Server (NTRS)

    Pierre, Christophe; Murthy, Durbha V.

    1993-01-01

    The aeroelastic characteristics of tuned and randomly mistuned blade assemblies which possess two blade-alone natural modes with close frequencies are studied. Modal interactions among the two blade modes are shown to be come extremely significant for small frequency separation. The two distinct loci of the aeroelastic eigenvalues, which characterize an assembly with well separated modes, fully merge into a single root locus as the blade-mode frequency separation vanishes. Also, while in the case of well separated blade modes the introduction of random mistuning into one blade mode affects only the assembly modes which are predominantly of that blade-mode type, mistuning results in the localization of all the assembly modes when the blade-alone natural frequencies are close. Results indicate that in the case of closely-spaced blade modes a single-degree of freedom blade model yields qualitatively erroneous results and that an N-blade assembly with two close blade modes behaves like an equivalent 2Nb-blade assembly with a single blade mode.

  6. Aerodynamic Investigation of Incidence Angle Effects in a Large Scale Transonic Turbine Cascade

    NASA Technical Reports Server (NTRS)

    McVetta, Ashlie B.; Giel, Paul W.; Welch, Gerard E.

    2013-01-01

    Aerodynamic measurements showing the effects of large incidence angle variations on an HPT turbine blade set are presented. Measurements were made in NASA's Transonic Turbine Blade Cascade Facility which has been used in previous studies to acquire detailed aerodynamic and heat transfer measurements for CFD code validation. The current study supports the development of variable-speed power turbine (VSPT) speed-change technology for the NASA Large Civil Tilt Rotor (LCTR) vehicle. In order to maintain acceptable main rotor propulsive efficiency, the VSPT operates over a nearly 50 percent speed range from takeoff to altitude cruise. This results in 50deg or more variations in VSPT blade incidence angles. The cascade facility has the ability to operate over a wide range of Reynolds numbers and Mach numbers, but had to be modified in order to accommodate the negative incidence angle variation required by the LCTR VSPT operation. Using existing blade geometry with previously acquired aerodynamic data, the tunnel was re-baselined and the new incidence angle range was exercised. Midspan exit total pressure and flow angle measurements were obtained at seven inlet flow angles. For each inlet angle, data were obtained at five flow conditions with inlet Reynolds numbers varying from 6.83×10(exp 5) to 0.85×10(exp 5) and two isentropic exit Mach numbers of 0.74 and 0.34. The midspan flowfield measurements were acquired using a three-hole pneumatic probe located in a survey plane 8.6 percent axial chord downstream of the blade trailing edge plane and covering three blade passages. Blade and endwall static pressure distributions were also acquired for each flow condition.

  7. Aerodynamic Investigation of Incidence Angle Effects in a Large Scale Transonic Turbine Cascade. Revision 1

    NASA Technical Reports Server (NTRS)

    McVetta, Ashlie B.; Giel, Paul W.; Welch, Gerard E.

    2014-01-01

    Aerodynamic measurements showing the effects of large incidence angle variations on an HPT turbine blade set are presented. Measurements were made in NASA's Transonic Turbine Blade Cascade Facility which has been used in previous studies to acquire detailed aerodynamic and heat transfer measurements for CFD code validation. The current study supports the development of variable-speed power turbine (VSPT) speed-change technology for the NASA Large Civil Tilt Rotor (LCTR) vehicle. In order to maintain acceptable main rotor propulsive efficiency, the VSPT operates over a nearly 50 percent speed range from takeoff to altitude cruise. This results in 50 deg or more variations in VSPT blade incidence angles. The cascade facility has the ability to operate over a wide range of Reynolds numbers and Mach numbers, but had to be modified in order to accommodate the negative incidence angle variation required by the LCTR VSPT operation. Using existing blade geometry with previously acquired aerodynamic data, the tunnel was re-baselined and the new incidence angle range was exercised. Midspan exit total pressure and flow angle measurements were obtained at seven inlet flow angles. For each inlet angle, data were obtained at five flow conditions with inlet Reynolds numbers varying from 6.83×10 (exp 5) to 0.85×10(exp 5) and two isentropic exit Mach numbers of 0.74 and 0.34. The midspan flowfield measurements were acquired using a three-hole pneumatic probe located in a survey plane 8.6 percent axial chord downstream of the blade trailing edge plane and covering three blade passages. Blade and endwall static pressure distributions were also acquired for each flow condition.

  8. Aerodynamic Investigation of Incidence Angle Effects in a Large Scale Transonic Turbine Cascade

    NASA Technical Reports Server (NTRS)

    McVetta, Ashlie B.; Giel, Paul W.; Welch, Gerard E.

    2012-01-01

    Aerodynamic measurements showing the effects of large incidence angle variations on an HPT turbine blade set are presented. Measurements were made in NASA's Transonic Turbine Blade Cascade Facility which has been used in previous studies to acquire detailed aerodynamic and heat transfer measurements for CFD code validation. The current study supports the development of variable-speed power turbine (VSPT) speed-change technology for the NASA Large Civil Tilt Rotor (LCTR) vehicle. In order to maintain acceptable main rotor propulsive efficiency, the VSPT operates over a nearly 50% speed range from takeoff to altitude cruise. This results in 50 degrees or more variations in VSPT blade incidence angles. The cascade facility has the ability to operate over a wide range of Reynolds numbers and Mach numbers, but had to be modified in order to accommodate the negative incidence angle variation required by the LCTR VSPT operation. Using existing blade geometry with previously acquired aerodynamic data, the tunnel was re-baselined and the new incidence angle range was exercised. Midspan exit total pressure and flow angle measurements were obtained at seven inlet flow angles. For each inlet angle, data were obtained at five flow conditions with inlet Reynolds numbers varying from 6.83 × 10(exp 5) to 0.85 ×10(exp 5) and two isentropic exit Mach numbers of 0.74 and 0.34. The midspan flowfield measurements were acquired using a three-hole pneumatic probe located in a survey plane 8.6% axial chord downstream of the blade trailing edge plane and covering three blade passages. Blade and endwall static pressure distributions were also acquired for each flow condition

  9. Analytical study on a two-dimensional plane of the off-design flow properties of tandem-bladed compressor stators

    NASA Technical Reports Server (NTRS)

    Sanger, N. L.

    1973-01-01

    The flow characteristics of several tandem bladed compressor stators were analytically evaluated over a range of inlet incidence angles. The ratios of rear-segment to front-segment chord and camber were varied. Results were also compared to the analytical performance of a reference solid blade section. All tandem blade sections exhibited lower calculated losses than the solid stator. But no one geometric configuration exhibited clearly superior characteristics. The front segment accepts the major effect of overall incidence angle change. Rear- to front-segment camber ratios of 4 and greater appeared to be limited by boundary-layer separation from the pressure surface of the rear segment.

  10. Complementary Aerodynamic Performance Datasets for Variable Speed Power Turbine Blade Section from Two Independent Transonic Turbine Cascades

    NASA Technical Reports Server (NTRS)

    Flegel, Ashlie B.; Welch, Gerard E.; Giel, Paul W.; Ames, Forrest E.; Long, Jonathon A.

    2015-01-01

    Two independent experimental studies were conducted in linear cascades on a scaled, two-dimensional mid-span section of a representative Variable Speed Power Turbine (VSPT) blade. The purpose of these studies was to assess the aerodynamic performance of the VSPT blade over large Reynolds number and incidence angle ranges. The influence of inlet turbulence intensity was also investigated. The tests were carried out in the NASA Glenn Research Center Transonic Turbine Blade Cascade Facility and at the University of North Dakota (UND) High Speed Compressible Flow Wind Tunnel Facility. A large database was developed by acquiring total pressure and exit angle surveys and blade loading data for ten incidence angles ranging from +15.8deg to -51.0deg. Data were acquired over six flow conditions with exit isentropic Reynolds number ranging from 0.05×106 to 2.12×106 and at exit Mach numbers of 0.72 (design) and 0.35. Flow conditions were examined within the respective facility constraints. The survey data were integrated to determine average exit total-pressure and flow angle. UND also acquired blade surface heat transfer data at two flow conditions across the entire incidence angle range aimed at quantifying transitional flow behavior on the blade. Comparisons of the aerodynamic datasets were made for three "match point" conditions. The blade loading data at the match point conditions show good agreement between the facilities. This report shows comparisons of other data and highlights the unique contributions of the two facilities. The datasets are being used to advance understanding of the aerodynamic challenges associated with maintaining efficient power turbine operation over a wide shaft-speed range.

  11. Investigation of Blade-row Flow Distributions in Axial-flow-compressor Stage Consisting of Guide Vanes and Rotor-blade Row

    NASA Technical Reports Server (NTRS)

    Mahoney, John J; Dugan, Paul D; Budinger, Raymond E; Goelzer, H Fred

    1950-01-01

    A 30-inch tip-diameter axial-flow compressor stage was investigated with and without rotor to determine individual blade-row performance, interblade-row effects, and outer-wall boundary-layer conditions. Velocity gradients at guide-vane outlet without rotor approximated design assumptions, when the measured variation of leaving angle was considered. With rotor in operation, Mach number and rotor-blade effects changed flow distribution leaving guide vanes and invalidated design assumption of radial equilibrium. Rotor-blade performance correlated interpolated two-dimensional results within 2 degrees, although tip stall was indicated in experimental and not two-dimensional results. Boundary-displacement thickness was less than 1.0 and 1.5 percent of passage height after guide vanes and after rotor, respectively, but increased rapidly after rotor when tip stall occurred.

  12. Impact behavior of graphite-epoxy simulated fan blades

    NASA Technical Reports Server (NTRS)

    Cook, T. S.; Preston, J. L., Jr.

    1977-01-01

    The response of a graphite-epoxy material, Modmor II/PR-286, to foreign object impact was investigated by impacting spherical projectiles of three different materials - gelatin, ice, and steel - on simulated blade specimens. Visual and metallographic inspection revealed three damage mechanisms: penetration, leading edge bending failure, and stress wave delamination and cracking. The steel projectiles caused penetration damage regardless of the impact location and angle. For the ice and gelatin particles impacting the leading edge, failure was due to large local bending strains, resulting in significant material removal and delamination damage.

  13. Multiple piece turbine rotor blade

    DOEpatents

    Kimmel, Keith D.; Plank, William L.

    2016-07-19

    A spar and shell turbine rotor blade with a spar and a tip cap formed as a single piece, the spar includes a bottom end with dovetail or fir tree slots that engage with slots on a top end of a root section, and a platform includes an opening on a top surface for insertion of the spar in which a shell made from an exotic high temperature resistant material is secured between the tip cap and the platform. The spar is tapered to form thinner walls at the tip end to further reduce the weight and therefore a pulling force due to blade rotation. The spar and tip cap piece is made from a NiAL material to further reduce the weight and the pulling force.

  14. Impact resistance of composite fan blades

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Results are presented of a program to determine the impact resistance of composite fan blades subjected to foreign object damage (FOD) while operating under conditions simulating a short take-off and landing (STOL) engine at takeoff. The full-scale TF39 first-stage fan blade was chosen as the base design for the demonstration component since its configuration and operating tip speeds are similar to a typical STOL fan blade several composite configurations had already been designed and evaluated under previous programs. The first portion of the program was devoted toward fabricating and testing high impact resistant, aerodynamically acceptable composite blades which utilized only a single material system in any given blade. In order to increase the blade impact capability beyond this point, several mixed material (hybrid) designs were investigated using S-glass and Kevlar as well as boron and graphite fibers. These hybrid composite blades showed a marked improvement in resistance to bird impact over those blades made of a single composite material. The work conducted under this program has demonstrated substantial improvement in composite fan blades with respect to FOD resistance and has indicated that the hybrid design concept, which utilizes different types of fibers in various portions of a fan blade design depending on the particular requirements of the different areas and the characteristics of the different fibers involved, shows a significant improvement over those designs utilizing only one material system.

  15. Flutter stability investigation of low-pressure steam turbine bladed disks

    SciTech Connect

    Omprakash, V.; Sarlashkar, A.V.; Lam, T.C.T.; Shuster, L.H.; McCloskey, T.H.

    1994-12-31

    This paper presents a numerical method to analyze flutter stability of low-pressure steam turbine blading. Any bladed disk normal vibration mode as well as the stage operating condition may be considered. The stability considerations are based on a quasi-steady power-per-vibration-cycle approach. The aerodynamic work per cycle of vibration of a bladed disk mode is calculated form the time integral of the product of the periodic time varying force and the specified harmonic vibration amplitude. The aerodynamic forces are obtained from the pressure distribution database generated from a separate 2-D cascade analysis for compressible inviscid flow for a wide range of flow angles. The method accounts for the kinematic corrections of instantaneous relative flow angle due to the vibratory motion. The non-linear material damping energy of the bladed disk as a function of the vibration amplitude is calculated using Lazan`s power law. The flutter stability is determined by the net power flow to the bladed disk at various amplitudes of vibration. Some results for the last stage of a low pressure steam turbine are presented.

  16. The Role of Free Stream Turbulence on the Aerodynamic Performance of a Wind Turbine Blade

    NASA Astrophysics Data System (ADS)

    Maldonado, Victor; Thormann, Adrien; Meneveau, Charles; Castillo, Luciano

    2014-11-01

    Effects of free stream turbulence with large integral scale on the aerodynamic performance of an S809 airfoil-based wind turbine blade at low Reynolds number are studied using wind tunnel experiments. A constant chord (2-D) S809 airfoil wind turbine blade model with an operating Reynolds number of 208,000 based on chord length was tested for a range of angles of attack representative of fully attached and stalled flow as encountered in typical wind turbine operation. The smooth-surface blade was subjected to a quasi-laminar free stream with very low free-stream turbulence as well as to elevated free-stream turbulence generated by an active grid. This turbulence contained large-scale eddies with levels of free-stream turbulence intensity of up to 6.14% and an integral length scale of about 60% of chord-length. The pressure distribution was acquired using static pressure taps and the lift was subsequently computed by numerical integration. The wake velocity deficit was measured utilizing hot-wire anemometry to compute the drag coefficient also via integration. In addition, the mean flow was quantified using 2-D particle image velocimetry (PIV) over the suction surface of the blade. Results indicate that turbulence, even with very large-scale eddies comparable in size to the chord-length, significantly improves the aerodynamic performance of the blade by increasing the lift coefficient and overall lift-to-drag ratio, L/D for all angles tested except zero degrees.

  17. Rotor blades for turbine engines

    SciTech Connect

    Piersall, Matthew R; Potter, Brian D

    2013-02-12

    A tip shroud that includes a plurality of damping fins, each damping fin including a substantially non-radially-aligned surface that is configured to make contact with a tip shroud of a neighboring rotor blade. At least one damping fin may include a leading edge damping fin and at least one damping fin may include a trailing edge damping fin. The leading edge damping fin may be configured to correspond to the trailing edge damping fin.

  18. Aerodynamic pressure and flow-visualization measurement from a rotating wind turbine blade

    SciTech Connect

    Butterfield, C P

    1988-11-01

    Aerodynamic, load, flow-visualization, and inflow measurements have been made on a 10-m, three-bladed, downwind, horizontal-axis wind turbine (HAWT). A video camera mounted on the rotor was used to record nighttime and daytime video images of tufts attached to the low-pressure side of a constant-chord, zero-twist blade. Load measurements were made using strain gages mounted at every 10% of the blade's span. Pressure measurements were made at 80% of the blade's span. Pressure taps were located at 32 chordwise positions, revealing pressure distributions comparable with wind tunnel data. Inflow was measured using a vertical-plane array of eight propvane and five triaxial (U-V-W) prop-type anemometers located 10 m upwind in the predominant wind direction. One objective of this comprehensive research program was to study the effects of blade rotation on aerodynamic behavior below, near, and beyond stall. To this end, flow patterns are presented here that reveal the dynamic and steady behavior of flow conditions on the blade. Pressure distributions are compared to flow patterns and two-dimensional wind tunnel data. Separation boundary locations are shown that change as a function of spanwise location, pitch angle, and wind speed. 6 refs., 23 figs., 1 tab.

  19. Blade Displacement Measurement Technique Applied to a Full-Scale Rotor Test

    NASA Technical Reports Server (NTRS)

    Abrego, Anita I.; Olson, Lawrence E.; Romander, Ethan A.; Barrows, Danny A.; Burner, Alpheus W.

    2012-01-01

    Blade displacement measurements using multi-camera photogrammetry were acquired during the full-scale wind tunnel test of the UH-60A Airloads rotor, conducted in the National Full-Scale Aerodynamics Complex 40- by 80-Foot Wind Tunnel. The objectives were to measure the blade displacement and deformation of the four rotor blades as they rotated through the entire rotor azimuth. These measurements are expected to provide a unique dataset to aid in the development and validation of rotorcraft prediction techniques. They are used to resolve the blade shape and position, including pitch, flap, lag and elastic deformation. Photogrammetric data encompass advance ratios from 0.15 to slowed rotor simulations of 1.0, thrust coefficient to rotor solidity ratios from 0.01 to 0.13, and rotor shaft angles from -10.0 to 8.0 degrees. An overview of the blade displacement measurement methodology and system development, descriptions of image processing, uncertainty considerations, preliminary results covering static and moderate advance ratio test conditions and future considerations are presented. Comparisons of experimental and computational results for a moderate advance ratio forward flight condition show good trend agreements, but also indicate significant mean discrepancies in lag and elastic twist. Blade displacement pitch measurements agree well with both the wind tunnel commanded and measured values.

  20. DESIGN OF TWO-DIMENSIONAL SUPERSONIC TURBINE ROTOR BLADES WITH BOUNDARY-LAYER CORRECTION

    NASA Technical Reports Server (NTRS)

    Goldman, L. J.

    1994-01-01

    A computer program has been developed for the design of supersonic rotor blades where losses are accounted for by correcting the ideal blade geometry for boundary layer displacement thickness. The ideal blade passage is designed by the method of characteristics and is based on establishing vortex flow within the passage. Boundary-layer parameters (displacement and momentum thicknesses) are calculated for the ideal passage, and the final blade geometry is obtained by adding the displacement thicknesses to the ideal nozzle coordinates. The boundary-layer parameters are also used to calculate the aftermixing conditions downstream of the rotor blades assuming the flow mixes to a uniform state. The computer program input consists essentially of the rotor inlet and outlet Mach numbers, upper- and lower-surface Mach numbers, inlet flow angle, specific heat ratio, and total flow conditions. The program gas properties are set up for air. Additional gases require changes to be made to the program. The computer output consists of the corrected rotor blade coordinates, the principal boundary-layer parameters, and the aftermixing conditions. This program is written in FORTRAN IV for batch execution and has been implemented on an IBM 7094. This program was developed in 1971.

  1. Sound generation by non-synchronously oscillating rotor blades in turbomachinery

    NASA Astrophysics Data System (ADS)

    Zhou, Di; Wang, Xiaoyu; Chen, Jun; Jing, Xiaodong; Sun, Xiaofeng

    2015-10-01

    In this paper, the sound generation by non-synchronously oscillating rotor blades in axial compressor is investigated with emphasis on establishing an analytical model for the corresponding sound field inside an annular duct. In terms of the present model, it is found that the acoustic frequency and propagating modes generated by non-synchronously oscillating rotor blades are not only associated with the blade vibration frequency and rotational speed, but also depend on the cascade inter-blade phase angle (IBPA) and the interaction between blades, which is clearly distinguished from typical Doppler effect. Moreover, it is also shown that although the IBPA of cascade is non-constant practically, the characteristics of sound generation are only slightly affected. Besides, the present work has conducted experimental investigations in order to gain insight into the generation mechanism of such complex sound field. Excellent agreement between the model prediction and experimental measurement in the near and far fields is generally observed in the circumstances with different parameter settings. Since the present study links the sound generation with blade oscillation, it would be very helpful to the fault diagnosis of rotor non-synchronous oscillation to some extent.

  2. Structural Analysis and Optimization of a Composite Fan Blade for Future Aircraft Engine

    NASA Astrophysics Data System (ADS)

    Coroneos, Rula M.; Gorla, Rama Subba Reddy

    2012-09-01

    This paper addresses the structural analysis and optimization of a composite sandwich ply lay-up of a NASA baseline solid metallic fan blade comparable to a future Boeing 737 MAX aircraft engine. Sandwich construction with a polymer matrix composite face sheet and honeycomb aluminum core replaces the original baseline solid metallic fan model made of Titanium. The focus of this work is to design the sandwich composite blade with the optimum number of plies for the face sheet that will withstand the combined pressure and centrifugal loads while the constraints are satisfied and the baseline aerodynamic and geometric parameters are maintained. To satisfy the requirements a sandwich construction for the blade is proposed with composite face sheets and a weak core made of honeycomb aluminum material. For aerodynamic considerations, the thickness of the core is optimized where as the overall blade thickness is held fixed in order not to alter the original airfoil geometry. Weight reduction is taken as the objective function by varying the core thickness of the blade within specified upper and lower bounds. Constraints are imposed on radial displacement limitations and ply failure strength. From the optimum design, the minimum number of plies, which will not fail, is back-calculated. The ply lay-up of the blade is adjusted from the calculated number of plies and final structural analysis is performed. Analyses were carried out by utilizing the OpenMDAO Framework, developed at NASA Glenn Research Center combining optimization with structural assessment.

  3. Influence of inflow angle on flexible flap aerodynamic performance

    NASA Astrophysics Data System (ADS)

    Y Zhao, H.; Ye, Z.; Li, Z. M.; Li, C.

    2013-12-01

    Large scale wind turbines have larger blade lengths and weights, which creates new challenges for blade design. This paper selects NREL S809 airfoil, and uses the parameterized technology to realize the flexible trailing edge deformation, researches the dynamic aerodynamic characteristics in the process of continuous flexible deformation, analyses the influence of inflow angle on flexible flap aerodynamic performance, in order to further realize the flexible wind turbine blade design and provides some references for the active control scheme. The results show that compared with the original airfoil, proper trailing edge deformation can improve the lift coefficient, reduce the drag coefficient, and thereby more efficiently realize flow field active control. With inflow angle increases, dynamic lift-drag coefficient hysteresis loop shape deviation occurs, even turns into different shapes. Appropriate swing angle can improve the flap lift coefficient, but may cause early separation of flow. To improve the overall performance of wind turbine blades, different angular control should be used at different cross sections, in order to achieve the best performance.

  4. Design and Evaluation of a Low-Noise Helicopter Blade

    NASA Astrophysics Data System (ADS)

    Kondo, Natsuki; Tsujiuchi, Tomoka; Murashige, Atsushi; Nishimura, Hiroki; Aoki, Makoto; Tsuchihashi, Akihiko; Yamakawa, Eiichi; Aoyama, Takashi; Saito, Shigeru

    A low-noise helicopter blade, AT1, was designed with the concept of reducing noise without the drop of rotor performance. In the concept, High-Speed Impulsive (HSI) noise is reduced by applying a thin airfoil in the tip region and a dog-tooth like extension in the leading-edge of the tip region. Blade-Vortex Interaction (BVI) noise is reduced by applying the extension and a strong taper near the tip end. The stall angle of the blade is increased by the effect of the vortex generated from the leading-edge extension. As a result, the drop of rotor performance caused by the thin airfoil and the reduction of rotor rotational speed is recovered. The low-noise characteristics and the performance of AT1 were evaluated by a model rotor test conducted at Deutsch Niederländischer Windkanal (DNW). It is shown that AT1 reduces HSI noise and BVI noise and has good performance in forward flight conditions. However, the improvement of performance in high-lift conditions still remains as a future problem.

  5. Structural tailoring of engine blades (STAEBL) theoretical manual

    NASA Technical Reports Server (NTRS)

    Brown, K. W.

    1985-01-01

    This Theoretical Manual includes the theories included in the Structural Tailoring of Engine Blades (STAEBL) computer program which was developed to perform engine fan and compressor blade numerical optimizations. These blade optimizations seek a minimum weight or cost design that satisfies practical blade design constraints, by controlling one to twenty design variables. The STAEBL constraint analyses include blade stresses, vibratory response, flutter, and foreign object damage. Blade design variables include airfoil thickness at several locations, blade chord, and construction variables: hole size for hollow blades, and composite material layup for composite blades.

  6. Structural tailoring of engine blades (STAEBL) user's manual

    NASA Technical Reports Server (NTRS)

    Brown, K. W.

    1985-01-01

    This User's Manual contains instructions and demonstration case to prepare input data, run, and modify the Structural Tailoring of Engine Blades (STAEBL) computer code. STAEBL was developed to perform engine fan and compressor blade numerical optimizations. This blade optimization seeks a minimum weight or cost design that satisfies realistic blade design constraints, by tuning one to twenty design variables. The STAEBL constraint analyses include blade stresses, vibratory response, flutter, and foreign object damage. Blade design variables include airfoil thickness at several locations, blade chord, and construction variables: hole size for hollow blades, and composite material layup for composite blades.

  7. Cooling arrangement for a tapered turbine blade

    SciTech Connect

    Liang, George

    2010-07-27

    A cooling arrangement (11) for a highly tapered gas turbine blade (10). The cooling arrangement (11) includes a pair of parallel triple-pass serpentine cooling circuits (80,82) formed in an inner radial portion (50) of the blade, and a respective pair of single radial channel cooling circuits (84,86) formed in an outer radial portion (52) of the blade (10), with each single radial channel receiving the cooling fluid discharged from a respective one of the triple-pass serpentine cooling circuit. The cooling arrangement advantageously provides a higher degree of cooling to the most highly stressed radially inner portion of the blade, while providing a lower degree of cooling to the less highly stressed radially outer portion of the blade. The cooling arrangement can be implemented with known casting techniques, thereby facilitating its use on highly tapered, highly twisted Row 4 industrial gas turbine blades that could not be cooled with prior art cooling arrangements.

  8. Impact testing on composite fan blades

    NASA Technical Reports Server (NTRS)

    Johns, R. H.

    1974-01-01

    The results of impact tests on large, fiber composite fan blades for aircraft turbofan engine applications are discussed. Solid composite blades of two different sizes and designs were tested. Both graphite/epoxy and boron/epoxy were evaluated. In addition, a spar-shell blade design was tested that had a boron/epoxy shell bonded to a titanium spar. All blades were tested one at a time in a rotating arm rig to simulate engine operating conditions. Impacting media included small gravel, two inch diameter ice balls, gelatin and RTV foam-simulated birds, as well as starlings and pigeons. The results showed little difference in performance between the graphite and boron/epoxy blades. The results also indicate that composite blades may be able to tolerate ice ball and small bird impacts but need improvement to tolerate birds in the small duck and larger category.

  9. FOD impact testing of composite fan blades

    NASA Technical Reports Server (NTRS)

    Johns, R. H.

    1974-01-01

    The results of impact tests on large, fiber composite fan blades for aircraft turbofan engine applications are discussed. Solid composite blades of two different sizes and designs were tested. Both graphite/epoxy and boron/epoxy were evaluated. In addition, a spar-shell blade design was tested that had a boron/epoxy shell bonded to a titanium spar. All blades were tested one at a time in a rotating arm rig to simulate engine operating conditions. Impacting media included small gravel, two inch diameter ice balls, gelatin and RTV foam-simulated birds, as well as starlings and pigeons. The results showed little difference in performance between the graphite and boron/epoxy blades. The results also indicate that composite blades may be able to tolerate ice ball and small bird impacts but need improvement to tolerate birds in the small duck and larger category.

  10. FOD impact testing of composite fan blades

    NASA Technical Reports Server (NTRS)

    Johns, R. H.

    1974-01-01

    The results of impact tests on large, fiber composite fan blades for aircraft turbofan engine applications are discussed. Solid composite blades of two different sizes and designs were tested. Both graphite/epoxy and boron/epoxy were evaluated. In addition, a spar-shell blade design was tested that had a boron/epoxy shell bonded to a titanium spar. All blades were tested one at a time in a rotating arm rig to simulate engine operating conditions. Impacting media included small gravel, two inch diameter ice balls, gelatin, and RTV foam-simulated birds, as well as starlings and pigeons. The results showed little difference in performance between the graphite and boron/epoxy blades. The results also indicate that composite blades may be able to tolerate ice ball and small bird impacts but need improvement to tolerate birds in the small duck and larger category.

  11. Advanced turbine blade tip seal system

    NASA Technical Reports Server (NTRS)

    Zelahy, J. W.

    1981-01-01

    An advanced blade/shroud system designed to maintain close clearance between blade tips and turbine shrouds and at the same time, be resistant to environmental effects including high temperature oxidation, hot corrosion, and thermal cycling is described. Increased efficiency and increased blade life are attained by using the advanced blade tip seal system. Features of the system include improved clearance control when blade tips preferentially wear the shrouds and a superior single crystal superalloy tip. The tip design, joint location, characterization of the single crystal tip alloy, the abrasive tip treatment, and the component and engine test are among the factors addressed. Results of wear testing, quality control plans, and the total manufacturing cycle required to fully process the blades are also discussed.

  12. Cyclic Structural Analyses of SSME Turbine Blades

    NASA Technical Reports Server (NTRS)

    Kaufman, A.; Manderscheid, J. M.

    1985-01-01

    The problems of calculating the structural response of high-temperature space propulsion components such as turbine blades for the fuel turbopump are addressed. The first high-pressure-stage fuel turbine blade (HPFTB) in the liquid-hydrogen turbopump of the space shuttle main engine (SSME) was selected for this study. In the past these blades have cracked in the blade shank region and at the airfoil leading edge adjacent to the platform. To achieve the necessary durability, these blades are currently being cast by using directional solidification. Single-crystal alloys are also being investigated for future SSME applications. The study evaluated the utility of advanced structural analysis methods in assessing the low-cycle fatigue lives of these anisotropic components. The turbine blade airfoil of the high-pressure stage of the SSME fuel turbopump was analyzed because it has a history of rapid crack initiation.

  13. Diagnostic methods of a bladed disc mode shape evaluation used for shrouded blades in steam turbines

    NASA Astrophysics Data System (ADS)

    Strnad, Jaromir; Liska, Jindrich

    2015-11-01

    This paper deals with advanced methods for the evaluation of a bladed disc behavior in terms of the wheel vibration and blade service time consumption. These methods are developed as parts of the noncontact vibration monitoring system of the steam turbine shrouded blades. The proposed methods utilize the time-frequency processing (cross spectra) and the method using least squares to analyse the data from the optical and magnetoresistive sensors, which are mounted in the stator radially above the rotor blades. Fundamentally, the blade vibrations are detected during the blade passages under the sensors and the following signal processing, which covers also the proposed methods, leads to the estimation of the blade residual service life. The prototype system implementing above mentioned techniques was installed into the last stage of the new steam turbine (LP part). The methods for bladed disc mode shape evaluation were successfully verified on the signals, which were obtained during the commission operation of the turbine.

  14. Finite element analysis of flexible, rotating blades

    NASA Technical Reports Server (NTRS)

    Mcgee, Oliver G.

    1987-01-01

    A reference guide that can be used when using the finite element method to approximate the static and dynamic behavior of flexible, rotating blades is given. Important parameters such as twist, sweep, camber, co-planar shell elements, centrifugal loads, and inertia properties are studied. Comparisons are made between NASTRAN elements through published benchmark tests. The main purpose is to summarize blade modeling strategies and to document capabilities and limitations (for flexible, rotating blades) of various NASTRAN elements.

  15. Experiments on sound radiation from propeller blades

    NASA Astrophysics Data System (ADS)

    Verhulst, K.; Debruijn, A.

    1981-08-01

    The effect of blade damping and air bubbles on cavitation noise radiation, and the damping effect of an antisinging edge were studied. Completely flat cunial and aluminum blades were used. One cunial blade had a viscoelastic sandwich layer. Cavitation was simulated by steam injection. The antisinging edge and viscoelastic layer have little effect. Aluminum reduces total sound power. When the distance of the bubble screen to the steam injection source is less than half a wavelength, radiated sound power is greatly reduced.

  16. Measurement of Oil Film Thickness between Bush and Blade in Swing Type Refrigerant Compressor

    NASA Astrophysics Data System (ADS)

    Tanaka, Shinji; Zuo, Siyang; Hikam, Achmad; Toyama, Toshiyuki

    A swing type refrigerant compressor was developed in order to overcome problems related to lubrication of a rotary compressor. However, the lubrication condition of the swing compressor has not been measured quantitatively yet. This paper describes an application of an eddy current displacement sensor to measure oil film thickness of a sliding part between a suction side bush and a blade in the swing compressor, and examined lubrication condition of the sliding part and a motion of the bush against the blade under some operating conditions. The results indicate that the sliding part between the suction side bush and the blade forms a wedge shape in shaft angle from 0° to 180° and forms a negative wedge shape in shaft angle from 180° to 360°. In addition, the results show that the oil film thickness on an upper edge side of the bush and a slope angle of the bush against the blade decrease with an increase of discharge pressure and increase with an increase of operating frequency of the compressor.

  17. Two-dimensional compressible flow in centrifugal compressors with straight blades

    NASA Technical Reports Server (NTRS)

    Stanitz, John D; Ellis, Gaylord O

    1950-01-01

    Six numerical examples are presented for steady, two-dimensional, compressible, nonviscous flow in centrifugal compressors with thin straight blades, the center lines of which generate the surface of a right circular cone when rotated about the axis of the compressor. A seventh example is presented for incompressible flow. The solutions were obtained in a region of the compressors, including the impeller tip, that was considered to be unaffected by the diffuser vanes or by the impeller-inlet configuration. Each solution applies to radial and mixed flow compressors with various cone angles but with the same angle between blades on the conic flow surface. The solution also apply to radial and mixed flow turbines with the rotation and the flow direction reversed. The effects of variations in the following parameters were investigated: (1) flow rate, (2) impeller-tip speed, (3) variation of passage height with radius, and (4) angle between blades on conic flow surface. The numerical results are presented in plots of the streamlines and constant Mach number lines. Correlation equations are developed whereby the flow conditions in any impeller with straight blades can be determined (in the region investigated by this analysis) for all operating conditions.

  18. Preliminary results of unsteady blade surface pressure measurements for the SR-3 propeller

    NASA Technical Reports Server (NTRS)

    Heidelberg, L. J.; Clark, B. J.

    1986-01-01

    Unsteady blade surface pressures were measured on an advanced, highly swept propeller known as SR-3. These measurements were obtained because the unsteady aerodynamics of these highly loaded transonic blades is important to noise generation and aeroelastic response. Specifically, the response to periodic angle-of-attack change was measured for both two- and eight-bladed configurations over a range of flight Mach numbers from 0.4 to 0.85. The periodic angle-of-attack change was obtained by placing the propeller axis at angles up to 4 deg to the flow. Most of the results are presented in terms of the unsteady pressure coefficient variation with Mach number. Both cascade and Mach number effects were largest on the suction surface near the leading edge. The results of a three-dimensional Euler code applied in a quasi-steady fashion were compared to measured data at the reduced frequency of 0.1 and showed relatively poor agreement. Pressure waveforms are shown that suggest shock phenomena may play an important part in the unsteady pressure response at some blade locations.

  19. Experimental determination of unsteady blade element aerodynamics in cascades. Volume 2: Translation mode cascade

    NASA Technical Reports Server (NTRS)

    Riffel, R. E.; Rothrock, M. D.

    1980-01-01

    A two dimensional cascade of harmonically oscillating airfoils was designed to model a near tip section from a rotor which was known to have experienced supersonic translational model flutter. This five bladed cascade had a solidity of 1.52 and a setting angle of 0.90 rad. Unique graphite epoxy airfoils were fabricated to achieve the realistic high reduced frequency level of 0.15. The cascade was tested over a range of static pressure ratios approximating the blade element operating conditions of the rotor along a constant speed line which penetrated the flutter boundary. The time steady and time unsteady flow field surrounding the center cascade airfoil were investigated.

  20. Three dimensional flow field inside compressor rotor, including blade boundary layers

    NASA Technical Reports Server (NTRS)

    Pouagare, M.; Lakshminarayana, B.; Galmes, J. M.

    1983-01-01

    The space marching code was modified in order to be able to predict the flow field inside a rotor passage, including the blade and hub wall boundary layers. The basic changes incorporated are modifications of the equations so that the code can handle three dimensional configurations with changes in the radial direction (for example changes in stagger angle, blade camber and thickness), extensions and modifications in order to implement a physically realistic turbulence model such as a k sigma model and an algebraic Reynolds stress model.

  1. Structural tailoring of engine blades (STAEBL)

    NASA Technical Reports Server (NTRS)

    Brown, K. W.; Pratt, T. K.; Chamis, C. C.

    1983-01-01

    Mathematical optimization is applied to the design of gas turbine fan blades. The automated procedure replaces the current manual process which requires experience and intuition on the part of the designer to achieve successful blade designs. The optimization procedure that is developed utilizes the COPES/CONMIN optimization code. Approximate vibration and stress analyses are used for the optimization process. Analysis recalibrations are achieved through the application of more detailed, refined analysis. Optimizations of a hollow titanium fan blade with composite inlays and of a superhybrid composite blade are demonstrated.

  2. Advanced optical blade tip clearance measurement system

    NASA Technical Reports Server (NTRS)

    Ford, M. J.; Honeycutt, R. E.; Nordlund, R. E.; Robinson, W. W.

    1978-01-01

    An advanced electro-optical system was developed to measure single blade tip clearances and average blade tip clearances between a rotor and its gas path seal in an operating gas turbine engine. This system is applicable to fan, compressor, and turbine blade tip clearance measurement requirements, and the system probe is particularly suitable for operation in the extreme turbine environment. A study of optical properties of blade tips was conducted to establish measurement system application limitations. A series of laboratory tests was conducted to determine the measurement system's operational performance characteristics and to demonstrate system capability under simulated operating gas turbine environmental conditions. Operational and environmental performance test data are presented.

  3. Impeller blade design method for centrifugal compressors

    NASA Technical Reports Server (NTRS)

    Jansen, W.; Kirschner, A. M.

    1974-01-01

    The design of a centrifugal impeller with blades that are aerodynamically efficient, easy to manufacture, and mechanically sound is discussed. The blade design method described here satisfies the first two criteria and with a judicious choice of certain variables will also satisfy stress considerations. The blade shape is generated by specifying surface velocity distributions and consists of straight-line elements that connect points at hub and shroud. The method may be used to design radially elemented and backward-swept blades. The background, a brief account of the theory, and a sample design are described.

  4. Flapping inertia for selected rotor blades

    NASA Technical Reports Server (NTRS)

    Berry, John D.; May, Matthew J.

    1991-01-01

    Aerodynamics of helicopter rotor systems cannot be investigated without consideration for the dynamics of the rotor. One of the principal properties of the rotor which affects the rotor dynamics is the inertia of the rotor blade about its root attachment. Previous aerodynamic investigation have been performed on rotor blades with a variety of planforms to determine the performance differences due to blade planform. The blades tested for this investigation have been tested on the U.S. Army 2 meter rotor test system (2MRTS) in the NASA Langley 14 by 22 foot subsonic tunnel for hover performance. This investigation was intended to provide fundamental information on the flapping inertia of five rotor blades with differing planforms. The inertia of the bare cuff and the cuff with a blade extension were also measured for comparison with the inertia of the blades. Inertia was determined using a swing testing technique, using the period of oscillation to determine the effective flapping inertia. The effect of damping in the swing test was measured and described. A comparison of the flapping inertials for rectangular and tapered planform blades of approximately the same mass showed the tapered blades to have a lower inertia, as expected.

  5. Fiber composite fan blade impact improvement

    NASA Technical Reports Server (NTRS)

    Graff, J.; Stoltze, L.; Varholak, E. M.

    1976-01-01

    The improved foreign object damage resistance of a metal matrix advanced composite fan blade was demonstrated. The fabrication, whirl impact test and subsequent evaluation of nine advanced composite fan blades of the "QCSEE" type design were performed. The blades were designed to operate at a tip speed of 282 m/sec. The blade design was the spar/shell type, consisting of a titanium spar and boron/aluminum composite airfoils. The blade retention was designed to rock on impact with large birds, thereby reducing the blade bending stresses. The program demonstrated the ability of the blades to sustain impacts with up to 681 g slices of birds at 0.38 rad with little damage (only 1.4 percent max weight loss) and 788 g slices of birds at 0.56 rad with only 3.2 percent max weight loss. Unbonding did not exceed 1.1 percent of the post-test blade area during any of the tests. All blades in the post-test condition were judged capable of operation in accordance with the FAA guidelines for medium and large bird impacts.

  6. Turbine blade tip with offset squealer

    DOEpatents

    Bunker, Ronald Scott

    2001-01-01

    An industrial turbine assembly comprises a plurality of rotating blade portions in a spaced relation with a stationary shroud. The rotating blade includes a root section, an airfoil having a pressure sidewall and a suction sidewall defining an outer periphery and a tip portion having a tip cap. An offset squealer is disposed on the tip cap. The offset squealer is positioned inward from the outer periphery of the rotating blade. The offset squealer increases the flow resistance and reduces the flow of hot gas flow leakage for a given pressure differential across the blade tip portion so as to improve overall turbine efficiency.

  7. Structural Testing of the Blade Reliability Collaborative Effect of Defect Wind Turbine Blades

    SciTech Connect

    Desmond, M.; Hughes, S.; Paquette, J.

    2015-06-08

    Two 8.3-meter (m) wind turbine blades intentionally constructed with manufacturing flaws were tested to failure at the National Wind Technology Center (NWTC) at the National Renewable Energy Laboratory (NREL) south of Boulder, Colorado. Two blades were tested; one blade was manufactured with a fiberglass spar cap and the second blade was manufactured with a carbon fiber spar cap. Test loading primarily consisted of flap fatigue loading of the blades, with one quasi-static ultimate load case applied to the carbon fiber spar cap blade. Results of the test program were intended to provide the full-scale test data needed for validation of model and coupon test results of the effect of defects in wind turbine blade composite materials. Testing was part of the Blade Reliability Collaborative (BRC) led by Sandia National Laboratories (SNL). The BRC seeks to develop a deeper understanding of the causes of unexpected blade failures (Paquette 2012), and to develop methods to enable blades to survive to their expected operational lifetime. Recent work in the BRC includes examining and characterizing flaws and defects known to exist in wind turbine blades from manufacturing processes (Riddle et al. 2011). Recent results from reliability databases show that wind turbine rotor blades continue to be a leading contributor to turbine downtime (Paquette 2012).

  8. Theory/test correlation of helicopter rotor blade element airloads in the blade stall regime

    NASA Technical Reports Server (NTRS)

    Bobo, C. J.

    1972-01-01

    The effects of stall on a rotor blade element in a three-dimensional rotating environment was investigated. The model rotor test provided blade element airloads and local boundary layer flow characteristics at the three-quarter blade radius position for a wide range of rotor operating conditions. A description of the test program and the test results are presented.

  9. Weight Assessment for Fuselage Shielding on Aircraft With Open-Rotor Engines and Composite Blade Loss

    NASA Technical Reports Server (NTRS)

    Carney, Kelly; Pereira, Michael; Kohlman, Lee; Goldberg, Robert; Envia, Edmane; Lawrence, Charles; Roberts, Gary; Emmerling, William

    2013-01-01

    The Federal Aviation Administration (FAA) has been engaged in discussions with airframe and engine manufacturers concerning regulations that would apply to new technology fuel efficient "openrotor" engines. Existing regulations for the engines and airframe did not envision features of these engines that include eliminating the fan blade containment systems and including two rows of counter-rotating blades. Damage to the airframe from a failed blade could potentially be catastrophic. Therefore the feasibility of using aircraft fuselage shielding was investigated. In order to establish the feasibility of this shielding, a study was conducted to provide an estimate for the fuselage shielding weight required to provide protection from an open-rotor blade loss. This estimate was generated using a two-step procedure. First, a trajectory analysis was performed to determine the blade orientation and velocity at the point of impact with the fuselage. The trajectory analysis also showed that a blade dispersion angle of 3deg bounded the probable dispersion pattern and so was used for the weight estimate. Next, a finite element impact analysis was performed to determine the required shielding thickness to prevent fuselage penetration. The impact analysis was conducted using an FAA-provided composite blade geometry. The fuselage geometry was based on a medium-sized passenger composite airframe. In the analysis, both the blade and fuselage were assumed to be constructed from a T700S/PR520 triaxially-braided composite architecture. Sufficient test data on T700S/PR520 is available to enable reliable analysis, and also demonstrate its good impact resistance properties. This system was also used in modeling the surrogate blade. The estimated additional weight required for fuselage shielding for a wing- mounted counterrotating open-rotor blade is 236 lb per aircraft. This estimate is based on the shielding material serving the dual use of shielding and fuselage structure. If the

  10. The Rene 150 directionally solidified superalloy turbine blades, volume 1

    NASA Technical Reports Server (NTRS)

    Deboer, G. J.

    1981-01-01

    Turbine blade design and analysis, preliminary Rene 150 system refinement, coating adaptation and evaluation, final Rene 150 system refinement, component-test blade production and evaluation, engine-test blade production, and engine test are discussed.

  11. Hot-blade stripper for polyester insulation on FCC

    NASA Technical Reports Server (NTRS)

    Angele, W.; Chambers, C. M.

    1971-01-01

    Stripper incorporates a blade which is electrically heated to a controlled temperature. Heated blade softens and strips insulation from cable while paper ribbon removes insulation material and keeps blade clean for next operation.

  12. Adaptor assembly for coupling turbine blades to rotor disks

    SciTech Connect

    Garcia-Crespo, Andres Jose; Delvaux, John McConnell

    2014-09-23

    An adaptor assembly for coupling a blade root of a turbine blade to a root slot of a rotor disk is described. The adaptor assembly includes a turbine blade having a blade root and an adaptor body having an adaptor root. The adaptor body defines a slot having an open end configured to receive the blade root of the turbine blade such that the adaptor root of the adaptor body and the blade root of the turbine blade are adjacent to one another when the blade root of the turbine blade is positioned within the slot. Both the adaptor root of the adaptor body and the blade root of the turbine blade are configured to be received within the root slot of the rotor disk.

  13. Viscoelastic Vibration Dampers for Turbomachine Blades

    NASA Technical Reports Server (NTRS)

    Nguyen, Nhan

    2003-01-01

    Simple viscoelastic dampers have been invented for use on the root attachments of turbomachine blades. These dampers suppress bending- and torsion-mode blade vibrations, which are excited by unsteady aerodynamic forces during operation. In suppressing vibrations, these dampers reduce fatigue (thereby prolonging blade lifetimes) while reducing noise. These dampers can be installed in new turbomachines or in previously constructed turbomachines, without need for structural modifications. Moreover, because these dampers are not exposed to flows, they do not affect the aerodynamic performances of turbomachines. Figure 1 depicts a basic turbomachine rotor, which includes multiple blades affixed to a hub by means of dovetail root attachments. Prior to mounting of the blades, thin layers of a viscoelastic material are applied to selected areas of the blade roots. Once the blades have been installed in the hub and the rotor is set into rotation, centrifugal force compresses these layers between the mating load-bearing surfaces of the hub and the blade root. The layers of viscoelastic material provide load paths through which the vibration energy of the blade can be dissipated. The viscoelasticity of the material converts mechanical vibration energy into shear strain energy and then from shear strain energy to heat. Of the viscoelastic materials that have been considered thus far for this application, the one of choice is a commercial polyurethane that is available in tape form, coated on one side with an adhesive that facilitates bonding to blade roots. The thickness of the tape can be chosen to suit the specific application. The typical thickness of 0.012 in. (.0.3 mm) is small enough that the tape can fit in the clearance between the mating blade-root and hub surfaces in a typical turbomachine. In an experiment, a blade was mounted in a test fixture designed to simulate the blade-end conditions that prevail in a turbocompressor. Vibrations were excited in the blade by

  14. Wave-induced dynamics of flexible blades

    NASA Astrophysics Data System (ADS)

    Luhar, M.; Nepf, H. M.

    2016-02-01

    We present an experimental and numerical study that describes the motion of flexible blades, scaled to be dynamically similar to natural aquatic vegetation, forced by wave-induced oscillatory flows. For the conditions tested, blade motion is governed primarily by two dimensionless variables: (i) the Cauchy number, $Ca$, which represents the ratio of the hydrodynamic forcing to the restoring force due to blade stiffness, and (ii) the ratio of the blade length to the wave orbital excursion, $L$. For flexible blades with $Ca \\gg 1$, the relationship between drag and velocity can be described by two different scaling laws at the large- and small-excursion limits. For large excursions ($L \\ll 1$), the flow resembles a unidirectional current and the scaling laws developed for steady-flow reconfiguration studies hold. For small excursions ($L \\gg 1$), the beam equations may be linearized and a different scaling law for drag applies. The experimental force measurements suggest that the small-excursion scaling applies even for intermediate cases with $L \\sim O(1)$. The numerical model employs the well-known Morison force formulation, and adequately reproduces the observed blade dynamics and measured hydrodynamic forces without the use of any fitted parameters. For $Ca \\gg 1$, the movement of the flexible blades reduces the measured and modeled hydrodynamic drag relative to a rigid blade of the same morphology. However, in some cases with $Ca \\sim O(1)$, the measured hydrodynamic forces generated by the flexible blades exceed those generated by rigid blades, but this is not reproduced in the model. Observations of blade motion suggest that this unusual behavior is related to an unsteady vortex shedding event, which the simple numerical model cannot reproduce. Finally, we also discuss implications for the modeling of wave energy dissipation over canopies of natural aquatic vegetation.

  15. Panel resonant behavior of wind turbine blades.

    SciTech Connect

    Paquette, Joshua A.; Griffith, Daniel Todd

    2010-03-01

    The principal design drivers in the certification of wind turbine blades are ultimate strength, fatigue resistance, adequate tip-tower clearance, and buckling resistance. Buckling resistance is typically strongly correlated to both ultimate strength and fatigue resistance. A composite shell with spar caps forms the airfoil shape of a blade and reinforcing shear webs are placed inside the blade to stiffen the blade in the flap-wise direction. The spar caps are dimensioned and the shear webs are placed so as to add stiffness to unsupported panel regions and reduce their length. The panels are not the major flap-wise load carrying element of a blade; however, they must be designed carefully to avoid buckling while minimizing blade weight. Typically, buckling resistance is evaluated by consideration of the load-deflection behavior of a blade using finite element analysis (FEA) or full-scale static testing of blades under a simulated extreme loading condition. The focus of this paper is on the use of experimental modal analysis to measure localized resonances of the blade panels. It can be shown that the resonant behavior of these panels can also provide a means to evaluate buckling resistance by means of analytical or experimental modal analysis. Further, panel resonances have use in structural health monitoring by observing changes in modal parameters associated with panel resonances, and use in improving panel laminate model parameters by correlation with test data. In recent modal testing of wind turbine blades, a set of panel modes were measured. This paper will report on the findings of these tests and accompanying numerical and analytical modeling efforts aimed at investigating the potential uses of panel resonances for blade evaluation, health monitoring, and design.

  16. Multiple piece turbine rotor blade

    SciTech Connect

    Jones, Russell B; Fedock, John A

    2013-05-21

    A multiple piece turbine rotor blade with a shell having an airfoil shape and secured between a spar and a platform with the spar including a tip end piece. a snap ring fits around the spar and abuts against the spar tip end piece on a top side and abuts against a shell on the bottom side so that the centrifugal loads from the shell is passed through the snap ring and into the spar and not through a tip cap dovetail slot and projection structure.

  17. Turbomachine blading with splitter blades designed by solving the inverse flow field problem

    NASA Astrophysics Data System (ADS)

    Luu, T. S.; Viney, B.; Bencherif, L.

    1992-04-01

    The paper presents an inverse method for the turbomachine blading design in incompressible non viscous flow in order to avoid cavitation and gives a new approach of the boundary conditions to be settled in relation with bound vorticity distribution on the blades. Treating first the 2D cascade design, it shows how the blade must be generated with the given thickness distribution and must be loaded in order to obtain the desired outlet flow angle. The 3D design is analysed by two steps S2-S1 approach proposed by Wu[1]. For the meridian flow (S2 approach), the blade thickness is taken into account by the modification of metric tensor in the continuity equation. The governing one is provided by the hub to shroud equilibrium condition and the meridian stream function is choosen to define the flow field. This step leads to the determination of axisymmetrical stream sheets as well as the approximate camber surface of the blades. In the second step, blade to blade flow (S1 approach) is analyzed. The governing equation is deduced from the momentum equation which implies that the vorticity of the absolute velocity must be tangential to the stream sheet. The bound vorticity distribution must be the same one as in S2 approach and the residual flux crossing over the blade be conservative (transpiration model). These two relations constitute the boundary conditions for the S1 flow. The detection of this residual flux due to the normal component of the relative velocity on the blade surface leads to the rectification of the camber surface. The optimized design of the blading of a centifugal impeller with splitter blades is presented. Pour définir la géométrie des aubages, les méthodes conventionnelles prennent la distribution de vitesse sur les deux faces de l'aube comme données initiales. En appliquant cette approche, on perd le contrôle de l'épaisseur de l'aube. Pour y remédier, la présente méthode suggère une méthode inverse en représentant les aubes par une

  18. Estimating Blade Section Airloads from Blade Leading-Edge Pressure Measurements

    NASA Technical Reports Server (NTRS)

    vanAken, Johannes M.

    2003-01-01

    The Tilt-Rotor Aeroacoustic Model (TRAM) test in the Duitse-Nederlandse Wind (DNW) Tunnel acquired blade pressure data for forward flight test conditions of a tiltrotor in helicopter mode. Chordwise pressure data at seven radial locations were integrated to obtain the blade section normal force. The present investigation evaluates the use of linear regression analysis and of neural networks in estimating the blade section normal force coefficient from a limited number of blade leading-edge pressure measurements and representative operating conditions. These network models are subsequently used to estimate the airloads at intermediate radial locations where only blade pressure measurements at the 3.5% chordwise stations are available.

  19. Carburetion system including an adjustable throttle linkage

    SciTech Connect

    Du Bois, C.G.; Falig, J.D.

    1986-03-25

    A throttle linkage assembly is described comprising a throttle shaft rotatable about a throttle shaft axis between an idle position and a wide open throttle position, a throttle plate fixed on the throttle shaft, a driven lever pivotable about the throttle shaft axis between various angles relative to the throttle plate, and means for fixing the driven lever at a selected angle relative to the throttle plate an adjustment lever fixedly connected to the throttle adjacent the driven lever, and means for releasably securing the driven lever to the adjustment lever.

  20. The effect of circumferential distortion on fan performance at two levels of blade loading

    NASA Technical Reports Server (NTRS)

    Hartmann, M. J.; Sanger, N. L.

    1975-01-01

    Single stage fans designed for two levels of pressure ratio or blade loading were subjected to screen-induced circumferential distortions of 90-degree extent. Both fan rotors were designed for a blade tip speed of 425 m/sec, blade solidity of 1.3 and a hub-to-tip radius ratio of 0.5. Circumferential measurements of total pressure, temperature, static pressure, and flow angle were obtained at the hub, mean and tip radii at five axial stations. Rotor loading level did not appear to have a significant influence on rotor response to distorted flow. Losses in overall pressure ratio due to distortion were most severe in the stator hub region of the more highly loaded stage. At the near stall operating condition tip and hub regions of (either) rotor demonstrated different response characteristics to the distorted flow. No effect of loading was apparent on interactions between rotor and upstream distorted flow fields.

  1. Rotor system having alternating length rotor blades for reducing blade-vortex interaction (BVI) noise

    NASA Technical Reports Server (NTRS)

    Moffitt, Robert C. (Inventor); Visintainer, Joseph A. (Inventor)

    1997-01-01

    A rotor system (4) having odd and even blade assemblies (O.sub.b, E.sub.b) mounting to and rotating with a rotor hub assembly (6) wherein the odd blade assemblies (O.sub.b) define a radial length R.sub.O, and the even blade assemblies (E.sub.b) define a radial length R.sub.E and wherein the radial length R.sub.E is between about 70% to about 95% of the radial length R.sub.O. Other embodiments of the invention are directed to a Variable Diameter Rotor system (4) which may be configured for operating in various operating modes for optimizing aerodynamic and acoustic performance. The Variable Diameter Rotor system (4) includes odd and even blade assemblies (O.sub.b, E.sub.b) having inboard and outboard blade sections (10, 12) wherein the outboard blade sections (12) telescopically mount to the inboard blade sections (10). The outboard blade sections (12) are positioned with respect to the inboard blade sections (10 such that the radial length R.sub.E of the even blade assemblies (E.sub.b) is equal to the radial length R.sub.O of the odd blade assemblies (O.sub.b) in a first operating mode, and such that the radial length R.sub.E is between about 70% to about 95% of the length R.sub.O in a second operating mode.

  2. Method of making counterrotating aircraft propeller blades

    NASA Technical Reports Server (NTRS)

    Nelson, Joey L. (Inventor); Elston, III, Sidney B. (Inventor); Tseng, Wu-Yang (Inventor); Hemsworth, Martin C. (Inventor)

    1990-01-01

    An aircraft propeller blade is constructed by forming two shells of composite material laminates and bonding the two shells to a metallic spar with foam filler pieces interposed between the shells at desired locations. The blade is then balanced radially and chordwise.

  3. Estimations of scale effects on blade cavitation

    NASA Astrophysics Data System (ADS)

    Amromin, Eduard

    2015-12-01

    Estimations of scale effects on blade cavitation require consideration of multiple models for both water flows and cavities. In particular, distinction of laminar and turbulent boundary layers is very important. A qualitative impact of selection of models is manifested for blade sheet cavitation. Its quantitative impact is shown for vortex cavitation inception.

  4. Massachusetts Large Blade Test Facility Final Report

    SciTech Connect

    Rahul Yarala; Rob Priore

    2011-09-02

    Project Objective: The Massachusetts Clean Energy Center (CEC) will design, construct, and ultimately have responsibility for the operation of the Large Wind Turbine Blade Test Facility, which is an advanced blade testing facility capable of testing wind turbine blades up to at least 90 meters in length on three test stands. Background: Wind turbine blade testing is required to meet international design standards, and is a critical factor in maintaining high levels of reliability and mitigating the technical and financial risk of deploying massproduced wind turbine models. Testing is also needed to identify specific blade design issues that may contribute to reduced wind turbine reliability and performance. Testing is also required to optimize aerodynamics, structural performance, encourage new technologies and materials development making wind even more competitive. The objective of this project is to accelerate the design and construction of a large wind blade testing facility capable of testing blades with minimum queue times at a reasonable cost. This testing facility will encourage and provide the opportunity for the U.S wind industry to conduct more rigorous testing of blades to improve wind turbine reliability.

  5. Prismatic Blade Measuring on a Wind Tunnel

    NASA Astrophysics Data System (ADS)

    Epikaridis, P.; Sedlak, k.; Stech, J.

    2013-04-01

    The results from measurement on the straight blade cascade are presented in the paper. The cascade is placed at the outlet of wind tunnel in ŠKODA POWER experimental base. The results in the form of velocity and loss fields behind blade cascade as well as the distribution of the loss coefficient in selected cross-section are evaluated.

  6. Composite hub/metal blade compressor rotor

    NASA Technical Reports Server (NTRS)

    Yao, S.

    1978-01-01

    A low cost compressor rotor was designed and fabricated for a small jet engine. The rotor hub and blade keepers were compression molded with graphite epoxy. Each pair of metallic blades was held in the hub by a keeper. All keepers were locked in the hub with circumferential windings. Feasibility of fabrication was demonstrated in this program.

  7. The use of carbon fibers in wind turbine blade design: A SERI-8 blade example

    SciTech Connect

    ONG,CHENG-HUAT; TSAI,STEPHEN W.

    2000-03-01

    The benefit of introducing carbon fibers in a wind turbine blade was evaluated. The SERI-8 wind turbine blade was used as a baseline for study. A model of the blade strength and stiffness properties was created using the 3D-Beam code; the predicted geometry and structural properties were validated against available data and static test results. Different enhanced models, which represent different volumes of carbon fibers in the blade, were also studied for two design options: with and without bend-twist coupling. Studies indicate that hybrid blades have excellent structural properties compared to the all-glass SERI-8 blade. Recurring fabrication costs were also included in the study. The cost study highlights the importance of the labor-cost to material-cost ratio in the cost benefits and penalties of fabrication of a hybrid glass and carbon blade.

  8. The role of blade elasticity in the prediction of blade-vortex interaction noise

    NASA Astrophysics Data System (ADS)

    Derham, Robert C.; Oh, Byung K.

    1991-05-01

    An analytical study of the role of a main rotor blade's flap, chord and torsional stiffnesses on vibratory airloads and sound pressures has been carried out. A rotor analysis code typically applied to blade dynamics and performance was modified to capture the airload due to blade-vortex and blade-wake interaction by using a finer azimuthal computation grid. The blade elasticity of the composite blade in this study is shown to have a significant influence upon the noise caused by blade-vortex interactions; the predicted sound pressures are shown to be especially sensitive to torsional stiffness. The effect of frequency placement and control system stiffness on sound levels is also discussed.

  9. Aerodynamic design and analysis of small horizontal axis wind turbine blades

    NASA Astrophysics Data System (ADS)

    Tang, Xinzi

    This work investigates the aerodynamic design and analysis of small horizontal axis wind turbine blades via the blade element momentum (BEM) based approach and the computational fluid dynamics (CFD) based approach. From this research, it is possible to draw a series of detailed guidelines on small wind turbine blade design and analysis. The research also provides a platform for further comprehensive study using these two approaches. The wake induction corrections and stall corrections of the BEM method were examined through a case study of the NREL/NASA Phase VI wind turbine. A hybrid stall correction model was proposed to analyse wind turbine power performance. The proposed model shows improvement in power prediction for the validation case, compared with the existing stall correction models. The effects of the key rotor parameters of a small wind turbine as well as the blade chord and twist angle distributions on power performance were investigated through two typical wind turbines, i.e. a fixed-pitch variable-speed (FPVS) wind turbine and a fixed-pitch fixed-speed (FPFS) wind turbine. An engineering blade design and analysis code was developed in MATLAB to accommodate aerodynamic design and analysis of the blades.. The linearisation for radial profiles of blade chord and twist angle for the FPFS wind turbine blade design was discussed. Results show that, the proposed linearisation approach leads to reduced manufacturing cost and higher annual energy production (AEP), with minimal effects on the low wind speed performance. Comparative studies of mesh and turbulence models in 2D and 3D CFD modelling were conducted. The CFD predicted lift and drag coefficients of the airfoil S809 were compared with wind tunnel test data and the 3D CFD modelling method of the NREL/NASA Phase VI wind turbine were validated against measurements. Airfoil aerodynamic characterisation and wind turbine power performance as well as 3D flow details were studied. The detailed flow

  10. Design optimization for active twist rotor blades

    NASA Astrophysics Data System (ADS)

    Mok, Ji Won

    This dissertation introduces the process of optimizing active twist rotor blades in the presence of embedded anisotropic piezo-composite actuators. Optimum design of active twist blades is a complex task, since it involves a rich design space with tightly coupled design variables. The study presents the development of an optimization framework for active helicopter rotor blade cross-sectional design. This optimization framework allows for exploring a rich and highly nonlinear design space in order to optimize the active twist rotor blades. Different analytical components are combined in the framework: cross-sectional analysis (UM/VABS), an automated mesh generator, a beam solver (DYMORE), a three-dimensional local strain recovery module, and a gradient based optimizer within MATLAB. Through the mathematical optimization problem, the static twist actuation performance of a blade is maximized while satisfying a series of blade constraints. These constraints are associated with locations of the center of gravity and elastic axis, blade mass per unit span, fundamental rotating blade frequencies, and the blade strength based on local three-dimensional strain fields under worst loading conditions. Through pre-processing, limitations of the proposed process have been studied. When limitations were detected, resolution strategies were proposed. These include mesh overlapping, element distortion, trailing edge tab modeling, electrode modeling and foam implementation of the mesh generator, and the initial point sensibility of the current optimization scheme. Examples demonstrate the effectiveness of this process. Optimization studies were performed on the NASA/Army/MIT ATR blade case. Even though that design was built and shown significant impact in vibration reduction, the proposed optimization process showed that the design could be improved significantly. The second example, based on a model scale of the AH-64D Apache blade, emphasized the capability of this framework to

  11. Prediction of sand particle trajectories and sand erosion damage on helicopter rotor blades

    NASA Astrophysics Data System (ADS)

    Shin, Bong Gun

    agreement with the experimental data. Next, second computational validation for flow around the SC1095 airfoil for various turbulence models were performed in order to select a suitable turbulence model. These results concluded that numerical results with k -- o SST model have a reasonably best accuracy. Relative inflow conditions to the blade section of helicopter rotor blades are highly dependent upon rotor blade geometric conditions and helicopter rotor operational conditions. Therefore, in this dissertation, 3D erosion simulations for four different rotating blades with uniform airfoil profile (SC1095) were performed in order to understand the details of erosion mechanism. These results indicate that erosion patterns including maximum erosion rate position and the extent of erosion damaged area on the blade section were highly dependent upon a spanwise twist distribution. It is found that the magnitude of erosion damage on the blade section is affected by not a spanwise twist but a swept tip. Next, in this dissertation, UH-60A helicopter rotor blades rotating in the computational domain for various collective pitch angles and climb velocities were simulated. These results indicate that overall erosion characteristics for helicopter rotor blades can be considered to be not dependent upon these operational parameters though there is a little difference in the magnitude of erosion damage and the maximum erosion rate position. These results concluded that a hover condition can be chosen as a reference operational condition for predicting erosion characteristics or for investigating erosion reduction methods. The final phase of this research is a generalization for particle trajectories and erosion characteristics on 3D helicopter rotor blades in order to reduce very expensive erosion computational cost. The generalized results show that aerodynamic and erosion characteristics for a 3D rotor blade can be predicted by using the 2D airfoil results for corresponding relative

  12. Interactive multi-mode blade impact analysis

    NASA Technical Reports Server (NTRS)

    Alexander, A.; Cornell, R. W.

    1978-01-01

    The theoretical methodology used in developing an analysis for the response of turbine engine fan blades subjected to soft-body (bird) impacts is reported, and the computer program developed using this methodology as its basis is described. This computer program is an outgrowth of two programs that were previously developed for the purpose of studying problems of a similar nature (a 3-mode beam impact analysis and a multi-mode beam impact analysis). The present program utilizes an improved missile model that is interactively coupled with blade motion which is more consistent with actual observations. It takes into account local deformation at the impact area, blade camber effects, and the spreading of the impacted missile mass on the blade surface. In addition, it accommodates plate-type mode shapes. The analysis capability in this computer program represents a significant improvement in the development of the methodology for evaluating potential fan blade materials and designs with regard to foreign object impact resistance.

  13. Advanced Blade Manufacturing Project - Final Report

    SciTech Connect

    POORE, ROBERT Z.

    1999-08-01

    The original scope of the project was to research improvements to the processes and materials used in the manufacture of wood-epoxy blades, conduct tests to qualify any new material or processes for use in blade design and subsequently build and test six blades using the improved processes and materials. In particular, ABM was interested in reducing blade cost and improving quality. In addition, ABM needed to find a replacement material for the mature Douglas fir used in the manufacturing process. The use of mature Douglas fir is commercially unacceptable because of its limited supply and environmental concerns associated with the use of mature timber. Unfortunately, the bankruptcy of FloWind in June 1997 and a dramatic reduction in AWT sales made it impossible for ABM to complete the full scope of work. However, sufficient research and testing were completed to identify several promising changes in the blade manufacturing process and develop a preliminary design incorporating these changes.

  14. Ice-impact analysis of blades

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Murthy, P. L. N.; Singhal, S. N.; Reddy, E. S.

    1994-01-01

    A computational capability is described for evaluating the ice-impact on engine blades made from composites. The ice block is modeled as an equivalent spherical object and has the velocity opposite to that of the aircraft with direction parallel to the engine axis. A finer finite element mesh is used for a portion of the blade near the impact region compared to the course mesh for the rest of the blade. The effects of ice size and velocity on the average leading edge strain are evaluated for a simulated unswept composite propfan blade. Parametric studies are performed to assess the blade structural responses due to the ice-impact at various locations along the span. It is found that: (1) for a given engine speed, a critical ice speed exists that corresponds to the maximum strain; and (2) the tip bending type frequencies increase after impact while the torsion frequencies decrease.

  15. Preliminary blade design using integrated computer codes

    NASA Astrophysics Data System (ADS)

    Ryan, Arve

    1988-12-01

    Loads on the root of a horizontal axis wind turbine (HAWT) rotor blade were analyzed. A design solution for the root area is presented. The loads on the blades are given by different load cases that are specified. To get a clear picture of the influence of different parameters, the whole blade is designed from scratch. This is only a preliminary design study and the blade should not be looked upon as a construction reference. The use of computer programs for the design and optimization is extensive. After the external geometry is set and the aerodynamic loads calculated, parameters like design stresses and laminate thicknesses are run through the available programs, and a blade design optimized on basis of facts and estimates used is shown.

  16. Turbine blade damping device with controlled loading

    SciTech Connect

    Marra, John J.

    2015-09-29

    A damping structure for a turbomachine rotor. The damping structure including an elongated snubber element including a first snubber end rigidly attached to a first blade and extending toward an adjacent second blade, and an opposite second snubber end positioned adjacent to a cooperating surface associated with the second blade. The snubber element has a centerline extending radially inwardly in a direction from the first blade toward the second blade along at least a portion of the snubber element between the first and second snubber ends. Rotational movement of the rotor effects relative movement between the second snubber end and the cooperating surface to position the second snubber end in frictional engagement with the cooperating surface with a predetermined damping force determined by a centrifugal force on the snubber element.

  17. Turbine blade damping device with controlled loading

    SciTech Connect

    Marra, John J

    2013-09-24

    A damping structure for a turbomachine rotor. The damping structure including an elongated snubber element including a first snubber end rigidly attached to a first blade and extending toward an adjacent second blade, and an opposite second snubber end positioned adjacent to a cooperating surface associated with the second blade. The snubber element has a centerline extending radially inwardly in a direction from the first blade toward the second blade along at least a portion of the snubber element between the first and second snubber ends. Rotational movement of the rotor effects relative movement between the second snubber end and the cooperating surface to position the second snubber end in frictional engagement with the cooperating surface with a predetermined damping force determined by a centrifugal force on the snubber element.

  18. Magnetic nondestructive testing of rotor blade tips

    NASA Astrophysics Data System (ADS)

    Cardelli, E.; Faba, A.; Marsili, R.; Rossi, G.; Tomassini, R.

    2015-05-01

    This paper deals with a particular magnetic nondestructive technique applied to the control of the position of the steel blades in rotating parts of turbines and engines. The working principle is based on a bridge of four identical magneto-resistive sensors. One sensor is placed near the blades, and the change in magnetic field produced by a permanent magnet and deviated by the change in position of the blade is detected by the sensor bridge. The position of the sensor is indicated, via dedicated FEM simulations, in order to have high sensitivity to the position change and high output signal. The accuracy and effectiveness of the proposed method are shown by experimental tests carried out in our laboratories. In particular, the tests indicate that the proposed magnetic nondestructive technique can be used in an almost large velocity range, and for quite different values of blade tip. The method seems also promising for the detection of blade vibrations.

  19. Combined Experimental and Numerical Simulations of Thermal Barrier Coated Turbine Blades Erosion

    NASA Technical Reports Server (NTRS)

    Hamed, Awate; Tabakoff, Widen; Swar, Rohan; Shin, Dongyun; Woggon, Nthanial; Miller, Robert

    2013-01-01

    A combined experimental and computational study was conducted to investigate the erosion of thermal barrier coated (TBC) blade surfaces by alumina particles ingestion in a single stage turbine. In the experimental investigation, tests of particle surface interactions were performed in specially designed tunnels to determine the erosion rates and particle restitution characteristics under different impact conditions. The experimental results show that the erosion rates increase with increased impingement angle, impact velocity and temperature. In the computational simulations, an Euler-Lagrangian two stage approach is used in obtaining numerical solutions to the three-dimensional compressible Reynolds Averaged Navier-Stokes equations and the particles equations of motion in each blade passage reference frame. User defined functions (UDF) were developed to represent experimentally-based correlations for particle surface interaction models which were employed in the three-dimensional particle trajectory simulations to determine the particle rebound characteristics after each surface impact. The experimentally based erosion UDF model was used to predict the TBC erosion rates on the turbine blade surfaces based on the computed statistical data of the particles impact locations, velocities and angles relative to the blade surface. Computational results are presented for the predicted TBC blade erosion in a single stage commercial APU turbine, for a NASA designed automotive turbine, and for the NASA turbine scaled for modern rotorcraft operating conditions. The erosion patterns in the turbines are discussed for uniform particle ingestion and for particle ingestion concentrated in the inner and outer 5 percent of the stator blade span representing the flow cooling the combustor liner.

  20. Divergent-ray projection method for measuring the flapping angle, lag angle, and torsional angle of a bumblebee wing

    NASA Astrophysics Data System (ADS)

    Zeng, Lijiang; Matsumoto, Hirokazu; Kawachi, Keiji

    1996-11-01

    A divergent-ray projection (DRP) method was developed for measuring the flapping angle, lag angle, and torsional angle of bumblebee wing during beating motion. This new method can measure the spatial coordinates of an insect wing by digitizing the images that are projected by two divergent laser rays from different directions. The advantage of the DRP method is its ability to measure those three angles simultaneously using only one high-speed camera. The resolution of the DRP method can be changed easily by adjusting system parameters to meet the needs of different types of objects. The measurement results for these angles of a bumblebee wing probe the effectiveness of the DRP method in studying the flight performance of insects.

  1. Effect of blade configuration, knife action, and intraocular pressure on keratotomy incision depth and shape.

    PubMed

    Melles, G R; Wijdh, R H; Cost, B; Beekhuis, W H; Binder, P S; van Rij, G; Groot, K

    1993-07-01

    For the same diamond blade extension, uphill (centripetal) radial keratotomy incision direction achieves greater depth and consequently greater refractive effect than downhill (centrifugal) incisions. To determine which factors may account for this difference, two uphill and two downhill incisions were made with a double-edged diamond blade set to 90% central pachometry in 26 human donor eyes at 15 or 60 mm Hg. Uphill incisions made with the perpendicular blade had greater mean incision depth than downhill incisions made with the oblique blade at 15 mm Hg (83.6 +/- 3.9% and 68.2 +/- 5.2%) (p < 0.0005) and at 60 mm Hg (86.3 +/- 3.1% and 79.7 +/- 1.7%) (p < 0.0005). Uphill and downhill incisions both made with the perpendicular blade had equal depth (85.4 +/- 4.9% and 83.7 +/- 3.5%) (p > 0.1). The perpendicular blade edge created a straight, and the oblique edge an S- or J-shaped, histological incision configuration. Corneal profile pictures taken during each incision showed the knife to tilt opposite of the incision direction and to move at a constant angle to the limbal plane, producing a smaller optical clear zone (OCZ) in the posterior stroma than intended with uphill incisions. Greater refractive effect with uphill incisions may be explained by the perpendicular blade being more effective in incising corneal lamellae, and the creation of a smaller posterior OCZ. Intraocular pressure variations during surgery may affect achieved incision depth of downhill, but not of uphill, incisions. PMID:8339558

  2. Peak power and blade loads on stall-regulated rotors as influenced by different airfoil families

    SciTech Connect

    Tangler, J.L.; Tu, P.K.C.

    1988-08-01

    At the Solar Energy Research Institute (SERI), new airfoils have been developed to help improve the performance and economics of horizontal-axis wind turbines (HAWTS). The objective of this study was to compare the performance characteristics of one of these airfoil families to other commonly used airfoil series for a typical three-bladed, stall-regulated HAWT. The traditional airfoil series chosen for comparison with SERI's new thin airfoil family were the NACA 23XXX, NACA 44XX, and NASA LS(1). The Micon 110 wind turbine was chosen because it is a typical three-bladed, stall-regulated rigid rotor system. The performance characteristics of the different airfoil series were derived analytically using the Eppler airfoil design code in the analysis mode. On a relative basis, this approach to comparing airfoils was considered more accurate than using airfoil performance characteristics based on wind-tunnel test data. After generating the performance characteristics for each airfoil series, the subsequent rotor performance and blade loads were calculated using SERI's PROPSH computer code. Resulting annual energy output, which is dependent on the wind-speed distribution, was calculated using SERI's Systems Engineering and Analysis Computer Code (SEACC). The results of the study show that fixed-wing airfoils generally result in excessive peak power for stall regulated, rigid rotors. By operating the wind turbine at a less desirable blade pitch angle, peak power can be reduced at the expense of higher mean blade loads and lower annual energy output. In contrast, the thin airfoil family was designed to reduce peak power at optimum blade pitch to minimize blade loads and maximize annual energy output. 7 refs., 12 figs.

  3. Application of Single Crystal Failure Criteria: Theory and Turbine Blade Case Study

    NASA Technical Reports Server (NTRS)

    Sayyah, Tarek; Swanson, Gregory R.; Schonberg, W. P.

    1999-01-01

    The orientation of the single crystal material within a structural component is known to affect the strength and life of the part. The first stage blade of the High Pressure Fuel Turbopump (HPFTP)/ Alternative Turbopump Development (ATD), of the Space Shuttle Main Engine (SSME) was used to study the effects of secondary axis'orientation angles on the failure rate of the blade. A new failure criterion was developed based on normal and shear strains on the primary crystallographic planes. The criterion was verified using low cycle fatigue (LCF) specimen data and a finite element model of the test specimens. The criterion was then used to study ATD/HPFTP first stage blade failure events. A detailed ANSYS finite element model of the blade was used to calculate the failure parameter for the different crystallographic orientations. A total of 297 cases were run to cover a wide range of acceptable orientations within the blade. Those orientations are related to the base crystallographic coordinate system that was created in the ANSYS finite element model. Contour plots of the criterion as a function of orientation for the blade tip and attachment were obtained. Results of the analysis revealed a 40% increase in the failure parameter due to changing of the primary and secondary axes of material orientations. A comparison between failure criterion predictions and actual engine test data was then conducted. The engine test data comes from two ATD/HPFTP builds (units F3- 4B and F6-5D), which were ground tested on the SSME at the Stennis Space Center in Mississippi. Both units experienced cracking of the airfoil tips in multiple blades, but only a few cracks grew all the way across the wall of the hollow core airfoil.

  4. Methodology of Blade Unsteady Pressure Measurement in the NASA Transonic Flutter Cascade

    NASA Technical Reports Server (NTRS)

    Lepicovsky, J.; McFarland, E. R.; Capece, V. R.; Jett, T. A.; Senyitko, R. G.

    2002-01-01

    In this report the methodology adopted to measure unsteady pressures on blade surfaces in the NASA Transonic Flutter Cascade under conditions of simulated blade flutter is described. The previous work done in this cascade reported that the oscillating cascade produced waves, which for some interblade phase angles reflected off the wind tunnel walls back into the cascade, interfered with the cascade unsteady aerodynamics, and contaminated the acquired data. To alleviate the problems with data contamination due to the back wall interference, a method of influence coefficients was selected for the future unsteady work in this cascade. In this approach only one blade in the cascade is oscillated at a time. The majority of the report is concerned with the experimental technique used and the experimental data generated in the facility. The report presents a list of all test conditions for the small amplitude of blade oscillations, and shows examples of some of the results achieved. The report does not discuss data analysis procedures like ensemble averaging, frequency analysis, and unsteady blade loading diagrams reconstructed using the influence coefficient method. Finally, the report presents the lessons learned from this phase of the experimental effort, and suggests the improvements and directions of the experimental work for tests to be carried out for large oscillation amplitudes.

  5. Application of higher harmonic blade feathering on the OH-6A helicopter for vibration reduction

    NASA Technical Reports Server (NTRS)

    Straub, F. K.; Byrns, E. V., Jr.

    1986-01-01

    The design, implementation, and flight test results of higher harmonic blade feathering for vibration reduction on the OH-6A helicopter are described. The higher harmonic control (HHC) system superimposes fourth harmonic inputs upon the stationary swashplate. These inputs are transformed into 3P, 4P and 5P blade feathering angles. This results in modified blade loads and reduced fuselage vibrations. The primary elements of this adaptive vibration suppression system are: (1) acceleration transducers sensing the vibratory response of the fuselage; (2) a higher harmonic blade pitch actuator system; (3) a flightworthy microcomputer, incorporating the algorithm for reducing vibrations, and (4) a signal conditioning system, interfacing between the sensors, the microcomputer and the HHC actuators. The program consisted of three distinct phases. First, the HHC system was designed and implemented on the MDHC OH-6A helicopter. Then, the open loop, or manual controlled, flight tests were performed, and finally, the closed loop adaptive control system was tested. In 1983, one portion of the closed loop testing was performed, and in 1984, additional closed loop tests were conducted with improved software. With the HHC system engaged, the 4P pilot seat vibration levels were significantly lower than the baseline ON-6A levels. Moreover, the system did not adversely affect blade loads or helicopter performance. In conclusion, this successful proof of concept project demonstrated HHC to be a viable vibration suppression mechanism.

  6. Flow structure generated by perpendicular blade-vortex interaction and implications for helicopter noise prediction. Volume 1: Measurements

    NASA Technical Reports Server (NTRS)

    Wittmer, Kenneth S.; Devenport, William J.

    1996-01-01

    The perpendicular interaction of a streamwise vortex with an infinite span helicopter blade was modeled experimentally in incompressible flow. Three-component velocity and turbulence measurements were made using a sub-miniature four sensor hot-wire probe. Vortex core parameters (radius, peak tangential velocity, circulation, and centerline axial velocity deficit) were determined as functions of blade-vortex separation, streamwise position, blade angle of attack, vortex strength, and vortex size. The downstream development of the flow shows that the interaction of the vortex with the blade wake is the primary cause of the changes in the core parameters. The blade sheds negative vorticity into its wake as a result of the induced angle of attack generated by the passing vortex. Instability in the vortex core due to its interaction with this negative vorticity region appears to be the catalyst for the magnification of the size and intensity of the turbulent flowfield downstream of the interaction. In general, the core radius increases while peak tangential velocity decreases with the effect being greater for smaller separations. These effects are largely independent of blade angle of attack; and if these parameters are normalized on their undisturbed values, then the effects of the vortex strength appear much weaker. Two theoretical models were developed to aid in extending the results to other flow conditions. An empirical model was developed for core parameter prediction which has some rudimentary physical basis, implying usefulness beyond a simple curve fit. An inviscid flow model was also created to estimate the vorticity shed by the interaction blade, and to predict the early stages of its incorporation into the interacting vortex.

  7. Comparison of strength and load-based methods for testing wind turbine blades

    SciTech Connect

    Musial, W.D.; Clark, M.E.; Egging, N.

    1996-11-01

    The purpose of this paper is to compare two methods of blade test loading and show how they are applied in an actual blade test. Strength and load-based methods were examined to determine the test load for an Atlantic Orient Corporation (AOC) 15/50 wind turbine blade for fatigue and static testing. Fatigue load-based analysis was performed using measured field test loads extrapolated for extreme rare events and scaled to thirty-year spectra. An accelerated constant amplitude fatigue test that gives equivalent damage at critical locations was developed using Miner`s Rule and the material S-N curves. Test load factors were applied to adjust the test loads for uncertainties, and differences between the test and operating environment. Similar analyses were carried, out for the strength-based fatigue test using the strength of the blade and the material properties to determine the load level and number of constant amplitude cycles to failure. Static tests were also developed using load and strength criteria. The resulting test loads were compared and contrasted. The analysis shows that, for the AOC 15/50 blade, the strength-based test loads are higher than any of the static load-based cases considered but were exceeded in the fatigue analysis for a severe hot/wet environment.

  8. Discharge coefficients of holes angled to the flow direction

    NASA Astrophysics Data System (ADS)

    Hay, N.; Henshall, S. E.; Manning, A.

    1992-06-01

    In the cooling passages of gas turbine blades, branches are often angled to the direction of the internal flow. This is particularly the case with film cooling holes. Accurate knowledge of the discharge coefficient of such holes at the design stage is vital so that the holes are correctly sized thus avoiding wastage of coolant and the formation of hot spots on the blade. This paper describes an experimental investigation to determine the discharge coefficient of 30 deg inclined holes with various degrees of inlet radiusing and with the axis of the hole at various orientation angles to the direction of the flow. Results are given for nominal main flow Mach numbers of 0, 0.15 and 0.3. The effects of radiusing, orientation and cross flow Mach number are quantified in the paper, the general trends are described, and the criteria for optimum performance are identified.

  9. Vertical axis windmill with multistage feathering of blades and safety storm control

    SciTech Connect

    Stepp, W.J.

    1983-09-27

    A windmill of the vertical axis type is claimed having a plurality of circumferentially and radially outwardly spaced rotatably mounted vanes vertically parallel to the axis shaft wherein means are provided for controlling multistage feathering of the vanes in conjunction with said vanes feathering to rotate on their individual axes in a direction opposite to the direction of rotation of the windmill assembly in increments of 45 degrees twice for each blade before finally feathering a final half rotation completing the rotation of 360 degrees on its individual axis while the windmill makes one revolution, thus repeatedly repositioning the blades to the most optimum resistance angle to the wind as the windmill rotates increasing the power angle to near seventy-five percent of the circle of the windmill rotation, a construction option prevailing to routinely cause all the blades to feather when near a zero angular position to the wind, and having associated therewith a conglomerate of mechanical phenomena to perform said functions and to release all blades in the event of a wind velocity exceeding a safe speed for the structure, bringing the windmill to a stop until the wind velocity recedes to a safe precalculated speed causing the windmill to automatically resume operation, characteristic of the total and complete automatism of this windmill.

  10. Investigation of Maximum Blade Loading Capability of Lift-Offset Rotors

    NASA Technical Reports Server (NTRS)

    Yeo, Hyeonsoo; Johnson, Wayne

    2013-01-01

    Maximum blade loading capability of a coaxial, lift-offset rotor is investigated using a rotorcraft configuration designed in the context of short-haul, medium-size civil and military missions. The aircraft was sized for a 6600-lb payload and a range of 300 nm. The rotor planform and twist were optimized for hover and cruise performance. For the present rotor performance calculations, the collective pitch angle is progressively increased up to and through stall with the shaft angle set to zero. The effects of lift offset on rotor lift, power, controls, and blade airloads and structural loads are examined. The maximum lift capability of the coaxial rotor increases as lift offset increases and extends well beyond the McHugh lift boundary as the lift potential of the advancing blades are fully realized. A parametric study is conducted to examine the differences between the present coaxial rotor and the McHugh rotor in terms of maximum lift capabilities and to identify important design parameters that define the maximum lift capability of the rotor. The effects of lift offset on rotor blade airloads and structural loads are also investigated. Flap bending moment increases substantially as lift offset increases to carry the hub roll moment even at low collective values. The magnitude of flap bending moment is dictated by the lift-offset value (hub roll moment) but is less sensitive to collective and speed.

  11. Adjustable extender for instrument module

    DOEpatents

    Sevec, J.B.; Stein, A.D.

    1975-11-01

    A blank extender module used to mount an instrument module in front of its console for repair or test purposes has been equipped with a rotatable mount and means for locking the mount at various angles of rotation for easy accessibility. The rotatable mount includes a horizontal conduit supported by bearings within the blank module. The conduit is spring-biased in a retracted position within the blank module and in this position a small gear mounted on the conduit periphery is locked by a fixed pawl. The conduit and instrument mount can be pulled into an extended position with the gear clearing the pawl to permit rotation and adjustment of the instrument.

  12. Aerodynamic development and investigation of turbine transonic rotor blade cascades

    NASA Astrophysics Data System (ADS)

    Mayorskiy, E. V.; Mamaev, B. I.

    2015-05-01

    An intricate nature of the pattern in which working fluid flows over transonic blade cascades generates the need for experimentally studying their characteristics in designing them. Three cascades having identical main geometrical parameters and differing from one another only in the suction side curvature in the outlet area between the throat and trailing edge were tested in optimizing the rotor blade cascade for the reduced flow outlet velocity λ2 ≈ 1. In initial cascade 1, its curvature decreased monotonically toward the trailing edge. In cascade 2, the suction side curvature near the trailing edge was decreased, but the section near the throat had a larger curvature. In cascade 3, a profile with inverse concavity near the trailing edge was used. The cascades were blown at λ2 = 0.7-1.2 and at different incidence angles. The distribution of pressure over the profiles, profile losses, and the outlet angle were measured. Cascade 1 showed efficient performance in the design mode and under the conditions of noticeable deviations from it with respect to the values of λ2 and incidence angle. In cascade 2, flow separation zones were observed at the trailing edge, as well as an increased level of losses. Cascade 3 was found to be the best one: it had reduced positive pressure gradients as compared with cascade 1, and the relative reduction of losses in the design mode was equal to 24%. The profiles with inverse concavity on the suction side near the trailing edge were recommended for being used in heavily loaded turbine stages.

  13. The use of paper honeycomb for prototype blade construction for small to medium-sized wind driven generators

    NASA Technical Reports Server (NTRS)

    Meyer, H.

    1973-01-01

    Paper honeycomb is used for the construction of conventional, propeller-type, windmill blades. Using fairly simple techniques and conventional power tools, it is possible to shape both simple foils and more complex foils with or without tapered plan forms and with or without varying profiles. A block of honeycomb, in its compressed form, is mounted on a wedge and run through a bandsaw with the table at an appropriate tilt angle. It is the combination of the wedge angle and the table angle that gives the tapered planform and profile shape. Next the honeycomb is expanded on the shaft and jigged to give the desired angles of attack. With the honeycomb fixed in position, the blade is covered with a fine weave fiberglass cloth. Any surface quality can then be achieved with filling and sanding.

  14. Flap-lag-torsional dynamic modelling of rotor blades in hover and in forward flight, including the effect of cubic nonlinearities

    NASA Technical Reports Server (NTRS)

    Crespodasilva, M. R. M.

    1981-01-01

    The differential equations of motion, and boundary conditions, describing the flap-lead/lag-torsional motion of a flexible rotor blade with a precone angle and a variable pitch angle, which incorporates a pretwist, are derived via Hamilton's principle. The meaning of inextensionality is discussed. The equations are reduced to a set of three integro partial differential equations by elimination of the extension variable. The generalized aerodynamic forces are modelled using Greenberg's extension of Theodorsen's strip theory. The equations of motion are systematically expanded into polynomial nonlinearities with the objective of retaining all terms up to third degree. The blade is modeled as a long, slender, of isotropic Hookean materials. Offsets from the blade's elastic axis through its shear center and the axes for the mass, area and aerodynamic centers, radial nonuniformaties of the blade's stiffnesses and cross section properties are considered and the effect of warp of the cross section is included in the formulation.

  15. Perception of Perspective Angles.

    PubMed

    Erkelens, Casper J

    2015-06-01

    We perceive perspective angles, that is, angles that have an orientation in depth, differently from what they are in physical space. Extreme examples are angles between rails of a railway line or between lane dividers of a long and straight road. In this study, subjects judged perspective angles between bars lying on the floor of the laboratory. Perspective angles were also estimated from pictures taken from the same point of view. Converging and diverging angles were judged to test three models of visual space. Four subjects evaluated the perspective angles by matching them to nonperspective angles, that is, angles between the legs of a compass oriented in the frontal plane. All subjects judged both converging and diverging angles larger than the physical angle and smaller than the angles in the proximal stimuli. A model of shallow visual space describes the results. According to the model, lines parallel to visual lines, vanishing at infinity in physical space, converge to visual lines in visual space. The perceived shape of perspective angles is incompatible with the perceived length and width of the bars. The results have significance for models of visual perception and practical implications for driving and flying in poor visibility conditions. PMID:27433312

  16. Perception of Perspective Angles

    PubMed Central

    2015-01-01

    We perceive perspective angles, that is, angles that have an orientation in depth, differently from what they are in physical space. Extreme examples are angles between rails of a railway line or between lane dividers of a long and straight road. In this study, subjects judged perspective angles between bars lying on the floor of the laboratory. Perspective angles were also estimated from pictures taken from the same point of view. Converging and diverging angles were judged to test three models of visual space. Four subjects evaluated the perspective angles by matching them to nonperspective angles, that is, angles between the legs of a compass oriented in the frontal plane. All subjects judged both converging and diverging angles larger than the physical angle and smaller than the angles in the proximal stimuli. A model of shallow visual space describes the results. According to the model, lines parallel to visual lines, vanishing at infinity in physical space, converge to visual lines in visual space. The perceived shape of perspective angles is incompatible with the perceived length and width of the bars. The results have significance for models of visual perception and practical implications for driving and flying in poor visibility conditions. PMID:27433312

  17. Method of making a wooden wind turbine blade

    DOEpatents

    Coleman, C.

    1984-08-14

    A wooden wind turbine blade is formed by laminating wood veneer in a compression mold having the exact curvature needed for one side of the blade, following which the other side of the blade is ground flat along its length but twisted with respect to the blade axis. 8 figs.

  18. Possibility of increasing durability of blades with damages

    NASA Astrophysics Data System (ADS)

    Boguslaev, V. A.

    The efficiency of a hardening method for titanium alloy gas-turbine compressor blades has been studied. It is shown that the hardening method is capable of increasing the durability of damaged blades by more than a factor of two. Cracks in these blades occur in a narrower zone and mainly on the side of the leading edge as compared with nonhardened blades.

  19. Method of making a wooden wind turbine blade

    DOEpatents

    Coleman, Clint

    1984-01-01

    A wooden wind turbine blade is formed by laminating wood veneer in a compression mold having the exact curvature needed for one side of the blade, following which the other side of the blade is ground flat along its length but twisted with respect to the blade axis.

  20. Mass balancing of hollow fan blades

    NASA Technical Reports Server (NTRS)

    Kielb, R. E.

    1986-01-01

    A typical section model is used to analytically investigate the effect of mass balancing as applied to hollow, supersonic fan blades. A procedure to determine the best configuration of an internal balancing mass to provide flutter alleviation is developed. This procedure is applied to a typical supersonic shroudless fan blade which is unstable in both the solid configuration and when it is hollow with no balancing mass. The addition of an optimized balancing mass is shown to stabilize the blade at the design condition.

  1. Predicted electrothermal deicing of aircraft blades

    NASA Technical Reports Server (NTRS)

    Keith, T. G., Jr.; Masiulaniec, K. C.; Dewitt, K. J.; Chao, D. F.

    1984-01-01

    A finite difference method is presented for the transient two-dimensional simulation of an electrothermal de-icer pad of an aircraft wing or blade. The irregular geometry of the composite ice laden blade is handled by use of a body fitted coordinate transformation. By this approach the various blade layers are mapped into a set of stacked rectangular strips in which the numerical solution takes place. Several heat conduction examples are presented in order to demonstrate the accuracy of the numerical procedure. Ice melting time predictions are made and compared to earlier predictions where possible. Finally, a new graphical presentation of thermal results is shown.

  2. Blade loss transient dynamic analysis of turbomachinery

    NASA Technical Reports Server (NTRS)

    Stallone, M. J.; Gallardo, V.; Storace, A. F.; Bach, L. J.; Black, G.; Gaffney, E. F.

    1982-01-01

    This paper reports on work completed to develop an analytical method for predicting the transient non-linear response of a complete aircraft engine system due to the loss of a fan blade, and to validate the analysis by comparing the results against actual blade loss test data. The solution, which is based on the component element method, accounts for rotor-to-casing rubs, high damping and rapid deceleration rates associated with the blade loss event. A comparison of test results and predicted response show good agreement except for an initial overshoot spike not observed in test. The method is effective for analysis of large systems.

  3. Vortex control for rotor blade devices

    NASA Technical Reports Server (NTRS)

    Greenblatt, David (Inventor)

    2008-01-01

    To control vortices originating at the tips of a rotor's blades rotating through the air at a revolution frequency f, separation control device(s) are actuated to periodically introduce perturbations into the airflow moving over the blades. The periodic introduction of perturbations is controlled in accordance with a periodic modulating frequency of introduction f.sub.0 while the frequency of the perturbations so-introduced is designated as f.sub.e. Vortex control is achieved when the periodic modulating frequency of introduction f.sub.0 satisfies the relationship nf.ltoreq.f.sub.0.ltoreq.f.sub.e where n is the number of blades.

  4. Three-axis adjustable loading structure

    NASA Technical Reports Server (NTRS)

    Lynch, E. J.; Gray, D. T. (Inventor)

    1973-01-01

    A three axis adjustable loading structure for testing the movable surfaces of aircraft by applying pressure, is described. The device has three electric drives where the wall angle, horizontal position, and vertical position of the test device can be rapidly and accurately positioned.

  5. Unsteady blade pressure measurements for the SR-7A propeller at cruise conditions

    NASA Technical Reports Server (NTRS)

    Heidelberg, L. J.; Nallasamy, M.

    1990-01-01

    The unsteady blade surface pressures were measured on the SR-7A propeller. The freestream Mach number, inflow angle, and advance ratio were varied while measurements were made at nine blade stations. At a freestream Mach number of 0.8, the data in terms of unsteady pressure coefficient versus azimuth angle are compared to an unsteady three-dimensional Euler solution, yielding very encouraging results. The code predicts the shape (phase) of the waveform very well, while the magnitude is over-predicted in many cases. At tunnel Mach numbers below 0.6, an unusually large response on the suction surface at 0.15 chord and 0.88 radius was observed. The behavior of this response suggests the presence of a leading-edge vortex.

  6. Unsteady blade pressure measurements for the SR-7A propeller at cruise conditions

    NASA Technical Reports Server (NTRS)

    Heidelberg, L. J.; Nallasamy, M.

    1990-01-01

    The unsteady blade surface pressures were measured on the SR-7A propeller. The freestream Mach no., inflow angle, and advance ratio were varied while measurements were made at nine blade stations. At a freestream Mach no. of 0.8, the data in terms of unsteady pressure coefficient vs. azimuth angle are compared to an unsteady 3-D Euler solution, yielding very encouraging results. The code predicts the shape (phase) of the waveform very well, while the magnitude is over-predicted in many cases. At tunnel Mach nos. below 0.6, an unusually large response on the suction surface at 0.15 chord and 0.88 radius was observed. The behavior of this response suggests the presence of a leading edge vortex. The midchord measuring stations on the suction surface exhibit a response that leads the forcing function while most other locations show a phase lag.

  7. Unsteady blade surface pressures on a large-scale advanced propeller - Prediction and data

    NASA Technical Reports Server (NTRS)

    Nallasamy, M.; Groeneweg, J. F.

    1990-01-01

    An unsteady three dimensional Euler analysis technique is employed to compute the flowfield of an advanced propeller operating at an angle of attack. The predicted blade pressure waveforms are compared with wind tunnel data at two Mach numbers, 0.5 and 0.2. The inflow angle is three degrees. For an inflow Mach number of 0.5, the predicted pressure response is in fair agreement with data: the predicted phases of the waveforms are in close agreement with data while the magnitudes are underpredicted. At the low Mach number of 0.2 (take-off) the numerical solution shows the formation of a leading edge vortex which is in qualitative agreement with measurements. However, the highly nonlinear pressure response measured on the blade suction surface is not captured in the present inviscid analysis.

  8. Unsteady blade-surface pressures on a large-scale advanced propeller: Prediction and data

    NASA Technical Reports Server (NTRS)

    Nallasamy, M.; Groeneweg, J. F.

    1990-01-01

    An unsteady 3-D Euler analysis technique is employed to compute the flow field of an advanced propeller operating at an angle of attack. The predicted blade pressure waveforms are compared with wind tunnel data at two Mach numbers, 0.5 and 0.2. The inflow angle is three degrees. For an inflow Mach number of 0.5, the predicted pressure response is in fair agreement with data: the predicted phases of the waveforms are in close agreement with data while the magnitudes are underpredicted. At the low Mach number of 0.2 (takeoff), the numerical solution shows the formation of a leading edge vortex which is in qualitative agreement with measurements. However, the highly nonlinear pressure response measured on the blade suction surface is not captured in the present inviscid analysis.

  9. Experimental determination of unsteady blade element aerodynamics in cascades. Volume 1: Torsion mode cascade

    NASA Technical Reports Server (NTRS)

    Riffel, R. E.; Rothrock, M. D.

    1980-01-01

    A two dimensional cascade of harmonically oscillating airfoils was designed to model a near tip section from a rotor which was known to have experienced supersonic torsional flutter. This five bladed cascade had a solidity of 1.17 and a setting angle of 1.07 rad. Graphite epoxy airfoils were fabricated to achieve the realistically high reduced frequency level of 0.44. The cascade was tested over a range of static pressure ratios approximating the blade element operating conditions of the rotor along a constant speed line which penetrated the flutter boundary. The time-steady and time-unsteady flow field surrounding the center cascade airfoil were investigated. The effects of reduced solidity and decreased setting angle on the flow field were also evaluated.

  10. The Langley 2,000-horsepower Propeller Dynamometer and Tests at High Speed of an NACA 10-(3)(08)-03 Two-blade Propeller

    NASA Technical Reports Server (NTRS)

    Corson, Blake W , Jr; Maynard, Julian D

    1952-01-01

    This paper contains a detailed description of a 2,000-horsepower propeller dynamometer used to make wind-tunnel tests of a two-blade NACA 10-(3)(08)-03 propeller for a range of blade angles from 20 degrees to 55 degrees at airspeeds up to 500 miles per hour. The results of these tests and comparisons with results obtained from a theoretical analysis and from previous tests made in other wind tunnels are presented.

  11. The effect of helicopter main rotor blade phasing and spacing on performance, blade loads, and acoustics

    NASA Technical Reports Server (NTRS)

    Gangwani, S. T.

    1976-01-01

    The performance, blade loads, and acoustic characteristics of a variable geometry rotor (VGR) system in forward flight and in a pullup maneuver were determined by the use of existing analytical programs. The investigation considered the independent effects of vertical separation of two three-bladed rotor systems as well as the effects of azimuthal spacing between the blades of the two rotors. The computations were done to determine the effects of these parameters on the performance, blade loads, and acoustic characteristics at two advance ratios in steady-state level flight and for two different g pullups at one advance ratio. To evaluate the potential benefits of the VGR concept in forward flight and pullup maneuvers, the results were compared as to performance, oscillatory blade loadings, vibratory forces transmitted to the fixed fuselage, and the rotor noise characteristics of the various VGR configurations with those of the conventional six-bladed rotor system.

  12. Studies of blade-vortex interaction noise reduction by rotor blade modification

    NASA Technical Reports Server (NTRS)

    Brooks, Thomas F.

    1993-01-01

    Blade-vortex interaction (BVI) noise is one of the most objectionable types of helicopter noise. This impulsive blade-slap noise can be particularly intense during low-speed landing approach and maneuvers. Over the years, a number of flight and model rotor tests have examined blade tip modification and other blade design changes to reduce this noise. Many times these tests have produced conflicting results. In the present paper, a number of these studies are reviewed in light of the current understanding of the BVI noise problem. Results from one study in particular are used to help establish the noise reduction potential and to shed light on the role of blade design. Current blade studies and some new concepts under development are also described.

  13. Comparison of Computational and Experimental Results for a Transonic Variable-Speed Power-Turbine Blade Operating with Low Inlet Turbulence Levels

    NASA Technical Reports Server (NTRS)

    Booth, David; Flegel, Ashlie

    2015-01-01

    A computational assessment of the aerodynamic performance of the midspan section of a variable-speed power-turbine blade is described. The computation comprises a periodic single blade that represents the 2-D Midspan section VSPT blade that was tested in the NASA Glenn Research Center Transonic Turbine Blade Cascade Facility. A commercial, off-the-shelf (COTS) software package, Pointwise and CFD++, was used for the grid generation and RANS and URANS computations. The CFD code, which offers flexibility in terms of turbulence and transition modeling options, was assessed in terms of blade loading, loss, and turning against test data from the transonic tunnel. Simulations were assessed at positive and negative incidence angles that represent the turbine cruise and take-off design conditions. The results indicate that the secondary flow induced at the positive incidence cruise condition results in a highly loaded case and transitional flow on the blade is observed. The negative incidence take-off condition is unloaded and the flow is very two-dimensional. The computational results demonstrate the predictive capability of the gridding technique and COTS software for a linear transonic turbine blade cascade with large incidence angle variation.

  14. Comparison of Computational and Experimental Results for a Transonic Variable-speed Power-Turbine Blade Operating with Low Inlet Turbulence Levels

    NASA Technical Reports Server (NTRS)

    Booth, David T.; Flegel, Ashlie B.

    2015-01-01

    A computational assessment of the aerodynamic performance of the midspan section of a variable-speed power-turbine blade is described. The computation comprises a periodic single blade that represents the 2-D Midspan section VSPT blade that was tested in the NASA Glenn Research Center Transonic Turbine Blade Cascade Facility. A commercial, off-the-shelf (COTS) software package, Pointwise and CFD++, was used for the grid generation and RANS and URANS computations. The CFD code, which offers flexibility in terms of turbulence and transition modeling options, was assessed in terms of blade loading, loss, and turning against test data from the transonic tunnel. Simulations were assessed at positive and negative incidence angles that represent the turbine cruise and take-off design conditions. The results indicate that the secondary flow induced at the positive incidence cruise condition results in a highly loaded case and transitional flow on the blade is observed. The negative incidence take-off condition is unloaded and the flow is very two-dimensional. The computational results demonstrate the predictive capability of the gridding technique and COTS software for a linear transonic turbine blade cascade with large incidence angle variation.

  15. Circuitry for Angle Measurements

    NASA Technical Reports Server (NTRS)

    Currie, J. R.; Kissel, R. R.

    1983-01-01

    Angle resolver pulsed and read under microprocessor control. Pulse generator excites resolver windings with dual slope pulse. System sequentially reads sine and cosine windings. Microprocessor determines angle through which resolver shaft turned from reference angle. Suitable applications include rate tables, antenna direction controllers, and machine tools.

  16. The effect of Reynolds number on transonic compressor blade rotor section

    NASA Astrophysics Data System (ADS)

    Beheshti Amiri, H.; Shahrabi Farahani, A.; Khazaei, H.

    2015-12-01

    In this paper, the effect of Reynolds number on transonic compressor blade rotor section is investigated. After passing through the first transonic compressor stages , the flow becomes remarkably compressed. In the present work, it is intended to numerically investigate the effects of the inflow Reynolds number on the unique incidence, flow losses, deviation angle, and shock position, at three different important points of "Minimum Loss" and "Choked Flow" in started conditions and "Stall Operation" in un-started conditions.

  17. Blade system design studies volume II : preliminary blade designs and recommended test matrix.

    SciTech Connect

    Griffin, Dayton A.

    2004-06-01

    As part of the U.S. Department of Energy's Wind Partnerships for Advanced Component Technologies (WindPACT) program, Global Energy Concepts, LLC is performing a Blade System Design Study (BSDS) concerning innovations in materials, processes and structural configurations for application to wind turbine blades in the multi-megawatt range. The BSDS Volume I project report addresses issues and constraints identified to scaling conventional blade designs to the megawatt size range, and evaluated candidate materials, manufacturing and design innovations for overcoming and improving large blade economics. The current report (Volume II), presents additional discussion of materials and manufacturing issues for large blades, including a summary of current trends in commercial blade manufacturing. Specifications are then developed to guide the preliminary design of MW-scale blades. Using preliminary design calculations for a 3.0 MW blade, parametric analyses are performed to quantify the potential benefits in stiffness and decreased gravity loading by replacement of a baseline fiberglass spar with carbon-fiberglass hybrid material. Complete preliminary designs are then presented for 3.0 MW and 5.0 MW blades that incorporate fiberglass-to-carbon transitions at mid-span. Based on analysis of these designs, technical issues are identified and discussed. Finally, recommendations are made for composites testing under Part I1 of the BSDS, and the initial planned test matrix for that program is presented.

  18. Pin and roller attachment system for ceramic blades

    DOEpatents

    Shaffer, James E.

    1995-01-01

    In a turbine, a plurality of blades are attached to a turbine wheel by way of a plurality of joints which form a rolling contact between the blades and the turbine wheel. Each joint includes a pin and a pair of rollers to provide rolling contact between the pin and an adjacent pair of blades. Because of this rolling contact, high stress scuffing between the blades and the turbine wheel reduced, thereby inhibiting catastrophic failure of the blade joints.

  19. Pin and roller attachment system for ceramic blades

    DOEpatents

    Shaffer, J.E.

    1995-07-25

    In a turbine, a plurality of blades are attached to a turbine wheel by way of a plurality of joints which form a rolling contact between the blades and the turbine wheel. Each joint includes a pin and a pair of rollers to provide rolling contact between the pin and an adjacent pair of blades. Because of this rolling contact, high stress scuffing between the blades and the turbine wheel reduced, thereby inhibiting catastrophic failure of the blade joints. 3 figs.

  20. Aircraft rotor blade with passive tuned tab

    NASA Technical Reports Server (NTRS)

    Campbell, T. G. (Inventor)

    1985-01-01

    A structure for reducing vibratory airloading in a rotor blade with a leading edge and a trailing edge includes a cut out portion at the trailing edge. A substantially wedge shaped cross section, inertially deflectable tab, also with a leading edge and a trailing edge is pivotally mounted in the cut out portion. The trailing edge of the tab may move above and below the rotor blade. A torsion strap applies force against the tab when the trailing edge of the tab is above and below the rotor blade. A restraining member is slidably movable along the torsion strap to vary torsional biasing force supplied by the torsion bar to the tab. A plurality of movable weights positioned between plates vary a center of gravity of the tab. Skin of the tab is formed from unidirectional graphite and fiberglass layers. Sliders coupled with a pinned degree of freedom at rod eliminate bending of tab under edgewise blade deflection.

  1. Structural analysis considerations for wind turbine blades

    NASA Technical Reports Server (NTRS)

    Spera, D. A.

    1979-01-01

    Approaches to the structural analysis of wind turbine blade designs are reviewed. Specifications and materials data are discussed along with the analysis of vibrations, loads, stresses, and failure modes.

  2. Composite Blade Structural Analyzer (COBSTRAN) demonstration manual

    NASA Technical Reports Server (NTRS)

    Aiello, Robert A.

    1989-01-01

    The input deck setup is described for a computer code, composite blade structural analyzer (COBSTRAN) which was developed for the design and analysis of composite turbofan and turboprop blades and also for composite wind turbine blades. This manual is intended for use in conjunction with the COBSTRAN user's manual. Seven demonstration problems are described with pre- and postprocessing input decks. Modeling of blades which are solid thru-the-thickness and also aircraft wing airfoils with internal spars is shown. Corresponding NASTRAN and databank input decks are also shown. Detail descriptions of each line of the pre- and post-processing decks is provided with reference to the Card Groups defined in the user's manual. A dictionary of all program variables and terms used in this manual may be found in Section 6 of the user's manual.

  3. Composite blade structural analyzer (COBSTRAN) user's manual

    NASA Technical Reports Server (NTRS)

    Aiello, Robert A.

    1989-01-01

    The installation and use of a computer code, COBSTRAN (COmposite Blade STRuctrual ANalyzer), developed for the design and analysis of composite turbofan and turboprop blades and also for composite wind turbine blades was described. This code combines composite mechanics and laminate theory with an internal data base of fiber and matrix properties. Inputs to the code are constituent fiber and matrix material properties, factors reflecting the fabrication process, composite geometry and blade geometry. COBSTRAN performs the micromechanics, macromechanics and laminate analyses of these fiber composites. COBSTRAN generates a NASTRAN model with equivalent anisotropic homogeneous material properties. Stress output from NASTRAN is used to calculate individual ply stresses, strains, interply stresses, thru-the-thickness stresses and failure margins. Curved panel structures may be modeled providing the curvature of a cross-section is defined by a single value function. COBSTRAN is written in FORTRAN 77.

  4. Blade Vibration Measurement System for Unducted Fans

    NASA Technical Reports Server (NTRS)

    Marscher, William

    2014-01-01

    With propulsion research programs focused on new levels of efficiency and noise reduction, two avenues for advanced gas turbine technology are emerging: the geared turbofan and ultrahigh bypass ratio fan engines. Both of these candidates are being pursued as collaborative research projects between NASA and the engine manufacturers. The high bypass concept from GE Aviation is an unducted fan that features a bypass ratio of over 30 along with the accompanying benefits in fuel efficiency. This project improved the test and measurement capabilities of the unducted fan blade dynamic response. In the course of this project, Mechanical Solutions, Inc. (MSI) collaborated with GE Aviation to (1) define the requirements for fan blade measurements; (2) leverage MSI's radar-based system for compressor and turbine blade monitoring; and (3) develop, validate, and deliver a noncontacting blade vibration measurement system for unducted fans.

  5. Wireless Inductive Power Device Suppresses Blade Vibrations

    NASA Technical Reports Server (NTRS)

    Morrison, Carlos R.; Provenza, Andrew J.; Choi, Benjamin B.; Bakhle, Milind A.; Min, James B.; Stefko, George L.; Duffy, Kirsten P.; Fougers, Alan J.

    2011-01-01

    Vibration in turbomachinery can cause blade failures and leads to the use of heavier, thicker blades that result in lower aerodynamic efficiency and increased noise. Metal and/or composite fatigue in the blades of jet engines has resulted in blade destruction and loss of lives. Techniques for suppressing low-frequency blade vibration, such as gtuned circuit resistive dissipation of vibratory energy, h or simply "passive damping," can require electronics incorporating coils of unwieldy dimensions and adding unwanted weight to the rotor. Other approaches, using vibration-dampening devices or damping material, could add undesirable weight to the blades or hub, making them less efficient. A wireless inductive power device (WIPD) was designed, fabricated, and developed for use in the NASA Glenn's "Dynamic Spin Rig" (DSR) facility. The DSR is used to simulate the functionality of turbomachinery. The relatively small and lightweight device [10 lb (approx.=4.5 kg)] replaces the existing venerable and bulky slip-ring. The goal is the eventual integration of this technology into actual turbomachinery such as jet engines or electric power generators, wherein the device will facilitate the suppression of potentially destructive vibrations in fan blades. This technology obviates slip rings, which require cooling and can prove unreliable or be problematic over time. The WIPD consists of two parts: a remote element, which is positioned on the rotor and provides up to 100 W of electrical power to thin, lightweight piezoelectric patches strategically placed on/in fan blades; and a stationary base unit that wirelessly communicates with the remote unit. The base unit supplies inductive power, and also acts as an input and output corridor for wireless measurement, and active control command to the remote unit. Efficient engine operation necessitates minimal disturbance to the gas flow across the turbine blades in any effort to moderate blade vibration. This innovation makes it

  6. ADJUSTABLE DOUBLE PULSE GENERATOR

    DOEpatents

    Gratian, J.W.; Gratian, A.C.

    1961-08-01

    >A modulator pulse source having adjustable pulse width and adjustable pulse spacing is described. The generator consists of a cross coupled multivibrator having adjustable time constant circuitry in each leg, an adjustable differentiating circuit in the output of each leg, a mixing and rectifying circuit for combining the differentiated pulses and generating in its output a resultant sequence of negative pulses, and a final amplifying circuit for inverting and square-topping the pulses. (AEC)

  7. Adjustable sutures in children.

    PubMed

    Engel, J Mark; Guyton, David L; Hunter, David G

    2014-06-01

    Although adjustable sutures are considered a standard technique in adult strabismus surgery, most surgeons are hesitant to attempt the technique in children, who are believed to be unlikely to cooperate for postoperative assessment and adjustment. Interest in using adjustable sutures in pediatric patients has increased with the development of surgical techniques specific to infants and children. This workshop briefly reviews the literature supporting the use of adjustable sutures in children and presents the approaches currently used by three experienced strabismus surgeons. PMID:24924284

  8. Design and validation of a high-lift low-pressure turbine blade

    NASA Astrophysics Data System (ADS)

    McQuilling, Mark Wayne

    This dissertation is a design and validation study of the high-lift low-pressure turbine (LPT) blade designated L2F. High-lift LPTs offer the promise of reducing the blade count in modern gas turbine engines. Decreasing the blade count can reduce development and maintenance costs and the weight of the engine, but care must be taken in order to maintain turbine section performance with fewer blades. For an equivalent amount of work extracted, lower blade counts increase blade loading in the LPT section. The high-lift LPT presented herein allows 38% fewer blades with a Zweifel loading coefficient of 1.59 and maintains the same inlet and outlet blade metal angles of conventional geometries in service today while providing an improved low-Reynolds number characteristic. The computational design method utilizes the Turbine Design and Analysis System (TDAAS) developed by John Clark of the Air Force Research Laboratory. TDAAS integrates several government-funded design utilities including airfoil and grid generation capability with a Reynolds-Averaged Navier-Stokes flow solver into a single, menu-driven, Matlab-based system. Transition modeling is achieved with the recently developed model of Praisner and Clark, and this study validates the use of the model for design purposes outside of the Pratt & Whitney (P&W) design system where they were created. Turbulence modeling is achieved with the Baldwin and Lomax zero-equation model. The experimental validation consists of testing the front-loaded L2F along with a previously designed, mid-loaded blade (L1M) in a linear turbine cascade in a low-speed wind tunnel over a range of Reynolds numbers at 3.3% freestream turbulence. Hot-wire anemometry and pressure measurements elucidate these comparisons, while a shear and stress sensitive film (S3F) also helps describe the flow in areas of interest. S3F can provide all 3 components of stress on a surface in a single measurement, and these tests extend the operational envelope of the

  9. Erosion-resistant coatings for gas turbine compressor blades

    NASA Astrophysics Data System (ADS)

    Muboyadzhyan, S. A.

    2009-06-01

    The effect of ion-plasma coatings made from high-hardness metal compounds on the erosion and corrosion resistance and the mechanical properties of alloy (substrate) + coating compositions is comprehensively studied. The effects of the thickness, composition, deposition conditions, and design of coatings based on metal nitrides and carbides on the relative gas-abrasive wear of alloy + coating compositions in a gas-abrasive flux are analyzed. The flux contains quartz sand with an average fraction of 300-350 μm; the abrasive feed rate is 200 g/min; and the angles of flux incidence are 20° (tangential flow) and 70° (near-head-on attack flow). Alloy + coating compositions based on VN, VC, Cr3C2, ZrN, and TiN coatings 15-30 μ m thick or more are shown to have high erosion resistance. A detailed examination of the coatings with high erosion resistance demonstrates that a zirconium nitride coating is most appropriate for protecting gas turbine compressor blades made of titanium alloys; this coating does not decrease the fatigue strength of these alloys. A chromium carbide coating is the best coating for protecting compressor steel blades.

  10. Morping blade design for vertical axis wind turbines

    NASA Astrophysics Data System (ADS)

    Macphee, David; Beyene, Asfaw

    2015-11-01

    Wind turbines operate at peak efficiency at a certain set of operational conditions. Away from these conditions, conversion efficiency drops significantly, requiring pitch and yaw control schemes to mitigate these losses. These efforts are an example of geometric variability, allowing for increased power production but with an unfortunate increase in investment cost to the energy conversion system. In Vertical-Axis Wind Turbines (VAWTs), the concept of pitch control is especially complicated due to a dependence of attack angle on armature azimuth. As a result, VAWT pitch control schemes, both active and passive, are as of yet unfeasible. This study investigates a low-cost, passive pitch control system, in which VAWT blades are constructed of a flexible material, allowing for continuous shape-morphing in response to local aerodynamic loading. This design is analyzed computationally using a finite-volume fluid-structure interaction routine and compared to a geometrically identical rigid rotor. The results indicate that the flexible blade increases conversion efficiency by reducing the severity of vortex shedding, allowing for greater average torque over a complete revolution.

  11. Tailoring optical complex field with spiral blade plasmonic vortex lens.

    PubMed

    Rui, Guanghao; Zhan, Qiwen; Cui, Yiping

    2015-01-01

    Optical complex fields have attracted increasing interests because of the novel effects and phenomena arising from the spatially inhomogeneous state of polarizations and optical singularities of the light beam. In this work, we propose a spiral blade plasmonic vortex lens (SBPVL) that offers unique opportunities to manipulate these novel fields. The strong interaction between the SBPVL and the optical complex fields enable the synthesis of highly tunable plasmonic vortex. Through theoretical derivations and numerical simulations we demonstrated that the characteristics of the plasmonic vortex are determined by the angular momentum (AM) of the light, and the geometrical topological charge of the SBPVL, which is govern by the nonlinear superposition of the pitch and the number of blade element. In addition, it is also shown that by adjusting the geometric parameters, SBPVL can be utilized to focus and manipulate optical complex field with fractional AM. This miniature plasmonic device may find potential applications in optical trapping, optical data storage and many other related fields. PMID:26335894

  12. Tailoring optical complex field with spiral blade plasmonic vortex lens

    PubMed Central

    Rui, Guanghao; Zhan, Qiwen; Cui, Yiping

    2015-01-01

    Optical complex fields have attracted increasing interests because of the novel effects and phenomena arising from the spatially inhomogeneous state of polarizations and optical singularities of the light beam. In this work, we propose a spiral blade plasmonic vortex lens (SBPVL) that offers unique opportunities to manipulate these novel fields. The strong interaction between the SBPVL and the optical complex fields enable the synthesis of highly tunable plasmonic vortex. Through theoretical derivations and numerical simulations we demonstrated that the characteristics of the plasmonic vortex are determined by the angular momentum (AM) of the light, and the geometrical topological charge of the SBPVL, which is govern by the nonlinear superposition of the pitch and the number of blade element. In addition, it is also shown that by adjusting the geometric parameters, SBPVL can be utilized to focus and manipulate optical complex field with fractional AM. This miniature plasmonic device may find potential applications in optical trapping, optical data storage and many other related fields. PMID:26335894

  13. Desulfurization Of Gas-Turbine Blades

    NASA Technical Reports Server (NTRS)

    Outlaw, Ronald A.

    1994-01-01

    Sulfur removed from nickel-base superalloy used to make gas-turbine blades by heating alloy and simultaneously subjecting it to sputtering by directed Ar(Sup+) ions from ion gun or from glow discharge. Reduction of sulfur content of superalloy by factor of 10 increases lifetime of turbine blade made of alloy by similar factor, because stability of protective surface oxide formed during operation of turbine increased.

  14. High efficiency turbine blade coatings.

    SciTech Connect

    Youchison, Dennis L.; Gallis, Michail A.

    2014-06-01

    The development of advanced thermal barrier coatings (TBCs) of yttria stabilized zirconia (YSZ) that exhibit lower thermal conductivity through better control of electron beam - physical vapor deposition (EB-PVD) processing is of prime interest to both the aerospace and power industries. This report summarizes the work performed under a two-year Lab-Directed Research and Development (LDRD) project (38664) to produce lower thermal conductivity, graded-layer thermal barrier coatings for turbine blades in an effort to increase the efficiency of high temperature gas turbines. This project was sponsored by the Nuclear Fuel Cycle Investment Area. Therefore, particular importance was given to the processing of the large blades required for industrial gas turbines proposed for use in the Brayton cycle of nuclear plants powered by high temperature gas-cooled reactors (HTGRs). During this modest (~1 full-time equivalent (FTE)) project, the processing technology was developed to create graded TBCs by coupling ion beam-assisted deposition (IBAD) with substrate pivoting in the alumina-YSZ system. The Electron Beam - 1200 kW (EB-1200) PVD system was used to deposit a variety of TBC coatings with micron layered microstructures and reduced thermal conductivity below 1.5 W/m.K. The use of IBAD produced fully stoichiometric coatings at a reduced substrate temperature of 600 oC and a reduced oxygen background pressure of 0.1 Pa. IBAD was also used to successfully demonstrate the transitioning of amorphous PVD-deposited alumina to the -phase alumina required as an oxygen diffusion barrier and for good adhesion to the substrate Ni2Al3 bondcoat. This process replaces the time consuming thermally grown oxide formation required before the YSZ deposition. In addition to the process technology, Direct Simulation Monte Carlo plume modeling and spectroscopic characterization of the PVD plumes were performed. The project consisted of five tasks. These included the production of layered

  15. Numerical and performance analysis of one row transonic rotor with sweep and lean angle

    NASA Astrophysics Data System (ADS)

    Razavi, Seyed Reza; Boroomand, Masoud

    2014-10-01

    In this study, aerodynamic behaviors of swept and leaned blades were investigated. Axial and tangential blade curvatures impacts on compressor's operating parameters were analyzed separately. A commercial CFD program which solves the Reynolds-averaged Navier-Stokes equations was used to find out the mentioned impact and the complicated flow field of transonic compressor-rotors. The CFD method that was used for solving flow field's equation was validated by experimental data of NASA Rotor 67. The results showed that the compressor with curved rotors had higher efficiency, rotor pressure ratio and stable operating range compared to the compressor with un-curved rotors. Using curved rotors mostly had higher impact on the overall stable operating range compared to the other operating parameters. Operating range involves choking point and stall point that were changed separately by using of bended blade. For finding the detailed impact of sweep and lean angle on transonic blades, various forms of lean and sweep angles were exerted to basic rotor. It was found that sweep angles increased overall operating range up to 30%, efficiency up to 2% and pressure ratio up to 1%. Leaning the blades increased the safe operating range, the pressure ratio and efficiency by 14%, 4% and 2% respectively.

  16. Composite rotor blades for wind turbine generators

    NASA Astrophysics Data System (ADS)

    Weigel, W. D.

    The materials, techniques, and methods used to construct a 150 ft test blade, two 31 ft blades for a 40 kW WECS, and rotor blades for the Mod-1 wind turbine are described. Considerations of strength, stiffness, and mass distributions, as well as cost, led to the choice of filament wound fiberglass/epoxy material using transverse filament tape which has structural fibers running across the width of the tape. A number of 90 deg windings were added to the rotor after tape winding to provide compaction and hoop strength. Curing comprised five hours at 180 F. The Mod-1 blades were required to match the steel blades in weight, stiffness, deflection, and frequencies. The finished product weighed 20,000 lb and featured a metal tip cap and braided wire trailing edge strap for lightning protection. The 40 kW was a NACA 23018 in the center and 23012 at the tip, while the Mod-1 blade was a NACA 23025 in the center and 23015 at the tip.

  17. Implant Angle Monitor System of MC3-II

    SciTech Connect

    Sato, Fumiaki; Sano, Makoto; Nakaoka, Hiroaki; Fujii, Yoshito; Kudo, Tetuya; Nakanishi, Makoto; Koike, Masazumi; Fujino, Yasushi

    2008-11-03

    Precise implant angle control is required for the latest generation of ion implanters to meet further shrink semiconductor device requirements. Especially, the highest angle accuracy is required for Halo implant process of Logic devices. The Halo implant angle affects the device performance, because slight differences of beam divergence change the overlap profile towards the extension. Additionally, twist angle accuracy is demanded in case of channeling angle implant. Therefore monitoring beam angles and wafer twist angles is important. A new monitoring system for the MC3-II, SEN Corp.'s single wafer type medium current implanter has been developed. This paper describes the angle control performance and monitoring system of the MC3-II. For the twist angle control, we developed a wafer notch angle monitor. The system monitors the wafer notch image on the platen. And the notch angle variation is calculated by using image processing method. It is also able to adjust the notch angle according to the angle error. For the tilt angle control, we developed a vertical beam profile monitor. The monitor system can detect beam profile of vertical directions with horizontally scanning beam. It also measures beam angles of a tilt direction to a wafer. The system configuration and sample beam data are presented.

  18. Inviscid analysis of unsteady blade tip flow correlation studies

    NASA Technical Reports Server (NTRS)

    Rao, B. M.; Maskew, B.

    1985-01-01

    Two computer programs, VSAERO-TS and VSAERO-H, were used for computing the unsteady subsonic aerodynamic characteristics of arbitrarily shaped wings oscillating in pitch. Program VSAERO-TS is a time-stepping analysis capable of treating large amplitude motions while program VSAERO-H uses harmonic wake and small amplitude assumptions. A comparison between the computed (VSAERO-TS and VSAERO-H) and DFVLR test results for chordwise pressure distributions for rectangular, swept, taper and ogee blade tips is presented in this report. A wide range of angles of attack (mean) from 0 to 12 deg and reduced frequencies of 0.1, 0.2 and 0.3 are covered in this report. Also, the comparison includes several spanwise stations.

  19. Dual-Laser Probe for Measuring Blade-Tip Clearance Tested

    NASA Technical Reports Server (NTRS)

    Dhadwal, Harbans S.; Kurkov, Anatole P.

    1999-01-01

    A dual-probe, integrated fiber-optic laser system for measuring blade tip clearance in rotating turbomachinery was developed cooperatively with Integrated Fiber Optic Systems, Inc., and tested at the NASA Lewis Research Center. Because the probes are nearly flush with the casing inner lining, there is minimal flow disturbance. The two probes are closely spaced in a circumferential plane and are slanted at an angle relative to each other so that the time it takes the blade tip to traverse the space between the two beams varies with the tip radius, making it possible to determine the tip clearance at rotor operating conditions. The tip clearance can be obtained for all the blades in a rotor with a single system, provided there are no synchronous vibrations present at a particular operating condition. The two probes for the laser system were installed in two holders. For one, the included angle between the probes was 20 degrees, and for the other, it was 40 degrees. The two configurations were calibrated in a vacuum spin-rig facility that can reproduce realistic blade-tip speeds. A specially designed, nondeflecting rotor was used to calibrate the probes. This rotor consisted of a tapered titanium bar with three teeth on each end, the thickness of which was representative of a typical blade-tip thickness. The bar and measuring teeth were in a horizontal plane in the spin rig, and the axis of rotation was vertical. To set the clearances, we used a remotely controlled optical stage that could be traversed vertically. The 40 probe system also was used to measure the tip clearance during an engine fan prototype test in a wind tunnel. Using the spin-rig calibrations, we estimated the accuracy of the tip-clearance measurement in the test to be 0.005 in. This program is ongoing.

  20. Turbine Blading Performance Evaluation Using Geometry Scanning and Flowfield Prediction Tools

    NASA Astrophysics Data System (ADS)

    Zachos, Pavlos K.; Pappa, Maria; Kalfas, Anestis I.; Mansour, Gabriel; Tsiafis, Ioannis; Pilidis, Pericles; Ohyama, Hiroharu; Watanabe, Eiichiro

    This paper investigates the effect of blade deformation, caused by manufacturing inaccuracies, on the performance of a 2-stage axial steam turbine. A high fidelity 3D coordinate Measurement Machine has been employed to obtain the exact geometrical model of the blades. A Streamline Curvature solver was used to predict the overall performance of the turbine. During the manufacturing process of the casts and of the blades themselves, several types of errors can occur which lead to a different geometry from that envisaged by the designer. The main objective of this study is to investigate the effect of those errors on the performance of a 2-stage experimental axial steam turbine. A high fidelity measurement of the actual geometry of both stator and rotor blades has been carried out, using a 3D Coordinate Measurement Machine. The cross sections of the blades obtained by the measurement were compared with those produced by the design process to evaluate the change in blade inlet/exit angles. In addition, the geometrical deviations from the initial design have been subjected to a statistical study in order to locate the nature of the error. The actual (measured) model has been used as input into a Streamline Curvature solver to evaluate its performance. Finally, a comparison with the performance plots of the original geometry has been carried out. A measurable change of efficiency as well as in the total power delivered by the turbine was found. This suggests that the accumulated error caused during the manufacturing procedure plays a significant role in the overall performance of the machine by making it less efficient by more than 1%. Reverse engineering techniques can be applied to predict and alleviate these errors leading thereby to a final design of each stage with improved performance.

  1. Application of dual-blade stator to low-speed ratio performance improvement of torque converters

    NASA Astrophysics Data System (ADS)

    Wu, Guangqiang; Wang, Lijun

    2016-03-01

    With application of the lock-up clutch in the torque converter (TC), fuel economy is not much determined by its high-speed ratio transmission efficiency. As a benefit, more researches are focused on its low-speed ratio performance so as to improve vehicle gradeability and launching acceleration performance. According to the results of computational fluid dynamics (CFD) analysis, hydrodynamic loss inside the stator cascade accounts for 42% of the total energy loss at stalling speed ratio. It is found that upstream flow with large impingement angle results in boundary layer separation at the leading edge, which aggregates hydrodynamic loss and decreases circular flow rate dramatically at low-speed ratio. In this paper, a dual-blade stator is proposed to suppress the boundary layer separation, which is parameterized by using the non-uniform rational B spline (NURBS) method. The mean camber line and blade profile curve are expressed by a three control points quadratic open NURBS and a cubic closed one respectively. The key design parameters included the slot width and suction side shape of the primary blade are analyzed. The most effective slot width is found to be between 4% and 8% chord length, and the boundary layer separation can be suppressed completely by decreasing distribution of momentum moment at the primary blade and adding it to the leading edge of the secondary blade. As a result, circular flow rate and impeller torque capacity is increased by 17.9% and 9.6% respectively at stalling speed ratio, meanwhile, low-speed ratio efficiency is also improved. Maximum efficiency at high-speed ratio decreases by 0.5%, which can be ignored as the work of lock-up clutch. This research focuses on using the dual-blade stator to optimize low-speed ratio performance of the TC, which is benefit to vehicle power performance.

  2. Navier-Stokes analysis of an oxidizer turbine blade with tip clearance

    NASA Technical Reports Server (NTRS)

    Gibeling, Howard J.; Sabnis, Jayant S.

    1992-01-01

    The Gas Generator Oxidizer Turbine (GGOT) Blade is being analyzed by various investigators under the NASA MSFC sponsored Turbine Stage Technology Team design effort. The present work concentrates on the tip clearance region flow and associated losses; however, flow details for the passage region are also obtained in the simulations. The present calculations simulate the rotor blade row in a rotating reference frame with the appropriate coriolis and centrifugal acceleration terms included in the momentum equation. The upstream computational boundary is located about one axial chord from the blade leading edge. The boundary conditions at this location were determined by using a Euler analysis without the vanes to obtain approximately the same flow profiles at the rotor as were obtained with the Euler stage analysis including the vanes. Inflow boundary layer profiles are then constructed assuming the skin friction coefficient at both the hub and the casing. The downstream computational boundary is located about one axial chord from the blade trailing edge, and the circumferentially averaged static pressure at this location was also obtained from the Euler analysis. Results were obtained for the 3-D baseline GGOT geometry at the full scale design Reynolds number. Details of the clearance region flow behavior and blade pressure distributions were computed. The spanwise variation in blade loading distributions are shown, and circumferentially averaged spanwise distributions of total pressure, total temperature, Mach number, and flow angle are shown at several axial stations. The spanwise variation of relative total pressure loss shows a region of high loss in the region near the casing. Particle traces in the near tip region show vortical behavior of the fluid which passes through the clearance region and exits at the downstream edge of the gap.

  3. Instability of a penetrating blade

    NASA Astrophysics Data System (ADS)

    Bigoni, D.; Bosi, F.; Dal Corso, F.; Misseroni, D.

    2014-03-01

    Application of a dead compressive load at the free end of an elastic rod (the ‘blade') induces its penetration into a sliding sleeve ending with a linear elastic spring. Bifurcation and stability analysis of this simple elastic system shows a variety of unexpected behaviors: (i) an increase of buckling load at decreasing of elastic stiffness; (ii) a finite number of buckling loads for a system with infinite degrees of freedom (leading to a non-standard Sturm-Liouville problem); (iii) more than one bifurcation load associated to each bifurcation mode; (iv) a restabilization of the straight configuration after the second bifurcation load associated to the first instability mode; (v) the presence of an Eshelby-like (or configurational) force, deeply influencing stability. Only the first of these behaviors was previously known, the second and third ones disprove common beliefs, the fourth highlights a sort of ‘island of instability', and the last one shows surprising phenomena and effects on stability.

  4. Impact resistant boron/aluminum composites for large fan blades

    NASA Technical Reports Server (NTRS)

    Oller, T. L.; Salemme, C. T.; Bowden, J. H.; Doble, G. S.; Melnyk, P.

    1977-01-01

    Blade-like specimens were subjected to static ballistic impact testing to determine their relative FOD impact resistance levels. It was determined that a plus or minus 15 deg layup exhibited good impact resistance. The design of a large solid boron/aluminum fan blade was conducted based on the FOD test results. The CF6 fan blade was used as a baseline for these design studies. The solid boron/aluminum fan blade design was used to fabricate two blades. This effort enabled the assessment of the scale up of existing blade manufacturing details for the fabrication of a large B/Al fan blade. Existing CF6 fan blade tooling was modified for use in fabricating these blades.

  5. A rapid blade-to-blade solution for use in turbomachinery design

    NASA Technical Reports Server (NTRS)

    Mcfarland, E. R.

    1982-01-01

    A rapid technique for solving the blade-to-blade turbomachinery flow problem was developed. Approximate governing flow equations, which include the effects of compressibility, radius change, rotation, and variable stream sheet thickness are solved using a panel method. The development and solution of these equations are described. Sample calculations are presented to illustrate the method's capabilities and accuracy.

  6. User's Guide to MBC3: Multi-Blade Coordinate Transformation Code for 3-Bladed Wind Turbine

    SciTech Connect

    Bir, G. S.

    2010-09-01

    This guide explains how to use MBC3, a MATLAB-based script NREL developed to perform multi-blade coordinate transformation of system matrices for three-bladed wind turbines. In its current form, MBC3 can be applied to system matrices generated by FAST.2.

  7. Structural tailoring of SSME turbopump blades (SSME/STAEBL). [Structural Tailoring of Engine Blades

    NASA Technical Reports Server (NTRS)

    Rubinstein, R.; Chamis, C. C.

    1986-01-01

    Computer structural optimization is applied to the design of Space Shuttle main engine turbopump blades. The optimization is implemented by the program SSME/STAEBL. A general description of this program is given. Design optimization studies for typical blade designs are presented.

  8. Preliminary Structural Design of Composite Blades for Two- and Three-Blade Rotors

    SciTech Connect

    Bir, G.; Migliore, P.

    2004-09-01

    A computerized method has been developed to aid in the preliminary design of composite wind turbine blades. The method allows for arbitrary specification of the chord, twist, and airfoil geometry along the blade and an arbitrary number of shear webs. Given the blade external geometry description and its design load distribution, the Fortran code uses ultimate-strength and buckling-resistance criteria to compute the design thickness of load-bearing composite laminates. The code also includes an analysis option to obtain blade properties if a composite laminates schedule is prescribed. These properties include bending stiffness, torsion stiffness, mass, moments of inertia, elastic-axis offset, and center-of-mass offset along the blade. Nonstructural materials-gelcoat, nexus, and bonding adhesive-are also included for computation of mass. The code includes an option to format the output properties that can be directly input to advanced aeroelastic codes. This report summarizes the structural layout of composite laminates within the blade, the design approach, and the computational process. Finally, we present the results of two composite blades designed using this code in support of a project covering comparison of two- and three-blade rotors for a hypothetical turbine.

  9. The SNL100-01 blade : carbon design studies for the Sandia 100-meter blade.

    SciTech Connect

    Griffith, Daniel Todd

    2013-02-01

    A series of design studies to investigate the effect of carbon on blade weight and performance for large blades was performed using the Sandia 100-meter All-glass Baseline Blade design as a starting point. This document provides a description of the final carbon blade design, which is termed as SNL100-01. This report includes a summary of the design modifications applied to the baseline all-glass 100-meter design and a description of the NuMAD model files that are made publicly available. This document is intended primarily to be a companion document to the distribution of the NuMAD blade model files for SNL100-01.

  10. Wind turbine blade shear web disbond detection using rotor blade operational sensing and data analysis.

    PubMed

    Myrent, Noah; Adams, Douglas E; Griffith, D Todd

    2015-02-28

    A wind turbine blade's structural dynamic response is simulated and analysed with the goal of characterizing the presence and severity of a shear web disbond. Computer models of a 5 MW offshore utility-scale wind turbine were created to develop effective algorithms for detecting such damage. Through data analysis and with the use of blade measurements, a shear web disbond was quantified according to its length. An aerodynamic sensitivity study was conducted to ensure robustness of the detection algorithms. In all analyses, the blade's flap-wise acceleration and root-pitching moment were the clearest indicators of the presence and severity of a shear web disbond. A combination of blade and non-blade measurements was formulated into a final algorithm for the detection and quantification of the disbond. The probability of detection was 100% for the optimized wind speed ranges in laminar, 30% horizontal shear and 60% horizontal shear conditions. PMID:25583871

  11. Cooled blades of gas turbines /Thermal design and profiling/

    NASA Astrophysics Data System (ADS)

    Kopelev, S. Z.

    The efficiency of the air-cooling of gas turbine blades is analyzed, and various approaches to the design of air-cooled gas turbine blades are discussed. In particular, attention is given to the analysis of heat transfer in blades with an internal deflector, blades with radial air flow, and blades with convective-barrier cooling. Methods for calculating the temperature of blades with transverse flow of the cooling air are discussed, as are methods for calculating losses in an air-cooled turbine.

  12. Determination of HART I Blade Structural Properties by Laboratory Testing

    NASA Technical Reports Server (NTRS)

    Jung, Sung N.; Lau, Benton H.

    2012-01-01

    The structural properties of higher harmonic Aeroacoustic Rotor Test (HART I) blades were measured using the original set of blades tested in the German-dutch wind tunnel (DNW) in 1994. the measurements include bending and torsion stiffness, geometric offsets, and mass and inertia properties of the blade. the measured properties were compared to the estimated values obtained initially from the blade manufacturer. The previously estimated blade properties showed consistently higher stiffness, up to 30 percent for the flap bending in the blade inboard root section.

  13. Bird impact analysis package for turbine engine fan blades

    NASA Technical Reports Server (NTRS)

    Hirschbein, M. S.

    1982-01-01

    A computer program has been developed to analyze the gross structural response of turbine engine fan blades subjected to bird strikes. The program couples a NASTRAN finite element model and modal analysis of a fan blade with a multi-mode bird impact analysis computer program. The impact analysis uses the NASTRAN blade model and a fluid jet model of the bird to interactively calculate blade loading during a bird strike event. The analysis package is computationaly efficient, easy to use and provides a comprehensive history of the gross structual blade response. Example cases are presented for a representative fan blade.

  14. Successful Solutions to SSME/AT Development Turbine Blade Distress

    NASA Technical Reports Server (NTRS)

    Montgomery, Stuart K.

    1999-01-01

    As part of the High-Pressure Fuel Turbopump/Alternate Turbopump (HPFTP/AT) turbine blade development program, unique turbine blade design features were implemented to address 2nd stage turbine blade high cycle fatigue distress and improve turbine robustness. Features included the addition of platform featherseal dampers, asymmetric blade tip seal segments, gold plating of the blade attachments, and airfoil tip trailing edge modifications. Development testing shows these features have eliminated turbine blade high cycle fatigue distress and consequently these features are currently planned for incorporation to the flight configuration. Certification testing will begin in 1999. This presentation summarizes these features.

  15. Aeroelastic response and stability of tiltrotors with elastically-coupled composite rotor blades. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Nixon, Mark W.

    1993-01-01

    There is a potential for improving the performance and aeroelastic stability of tiltrotors through the use of elastically-coupled composite rotor blades. To study the characteristics of tiltrotors with these types of rotor blades it is necessary to formulate a new analysis which has the capabilities of modeling both a tiltrotor configuration and an anisotropic rotor blade. Background for these formulations is established in two preliminary investigations. In the first, the influence of several system design parameters on tiltrotor aeroelastic stability is examined for the high-speed axial flight mode using a newly-developed rigid-blade analysis with an elastic wing finite element model. The second preliminary investigation addresses the accuracy of using a one-dimensional beam analysis to predict frequencies of elastically-coupled highly-twisted rotor blades. Important aspects of the new aeroelastic formulations are the inclusion of a large steady pylon angle which controls tilt of the rotor system with respect to the airflow, the inclusion of elastic pitch-lag coupling terms related to rotor precone, the inclusion of hub-related degrees of freedom which enable modeling of a gimballed rotor system and engine drive-train dynamics, and additional elastic coupling terms which enable modeling of the anisotropic features for both the rotor blades and the tiltrotor wing. Accuracy of the new tiltrotor analysis is demonstrated by a comparison of the results produced for a baseline case with analytical and experimental results reported in the open literature. Two investigations of elastically tailored blades on a baseline tiltrotor are then conducted. One investigation shows that elastic bending-twist coupling of the rotor blade is a very effective means for increasing the flutter velocity of a tiltrotor, and the magnitude of coupling required does not have an adverse effect on performance or blade loads. The second investigation shows that passive blade twist control via

  16. Aerodynamic Measurements of a Variable-Speed Power-Turbine Blade Section in a Transonic Turbine Cascade

    NASA Technical Reports Server (NTRS)

    Flegel, Ashlie B.

    2014-01-01

    The purpose of this thesis is to document the impact of incidence angle and Reynolds number variations on the three-dimensional flow field and midspan loss and turning of a two-dimensional section of a variable-speed power-turbine (VSPT) rotor blade. Aerodynamic measurements were obtained in a transonic linear cascade at NASA Glenn Research Center in Cleveland, Ohio. Steady-state data were obtained for 10 incidence angles ranging from +15.8deg to -51.0deg. At each angle, data were acquired at five flow conditions with the exit Reynolds number (based on axial chord) varying over an order-of-magnitude from 2.12×105 to 2.12×106. Data were obtained at the design exit Mach number of 0.72 and at a reduced exit Mach number of 0.35 as required to achieve the lowest Reynolds number. Midspan tota lpressure and exit flow angle data were acquired using a five-hole pitch/yaw probe surveyed on a plane located 7.0 percent axial-chord downstream of the blade trailing edge plane. The survey spanned three blade passages. Additionally, three-dimensional half-span flow fields were examined with additional probe survey data acquired at 26 span locations for two key incidence angles of +5.8deg and -36.7deg. Survey data near the endwall were acquired with a three-hole boundary-layer probe. The data were integrated to determine average exit total-pressure and flow angle as functions of incidence and flow conditions. The data set also includes blade static pressures measured on four spanwise planes and endwall static pressures.

  17. Performance of Single-Stage Turbine of Mark 25 Torpedo Power Plant with Two Special Nozzles. III; Efficiency with Standard Rotor Blades

    NASA Technical Reports Server (NTRS)

    Schum, Harold J.; Whitney, Warren J.

    1949-01-01

    A Mark 25 torpedo power plant modified to operate as a single-stage turbine was investigated to determine the performance with two nozzle designs and a standard first-stage rotor having 0.40-inch blades with a 17O met-air angle. Both nozzles had smaller port cross-sectional areas than those nozzles of similar design, which were previously investigated. The performance of the two nozzles was compared on the basis of blade, rotor, and brake efficiencies as a function of blade-jet speed ratio for pressure ratios of 8, 15 (design), and 20. At pressure ratios of 15 and 20, the blade efficiency obtained with the nozzle having circular passages (K) was higher than that obtained with the nozzle having rectangular passages (J). At a pressure ratio of 8, the efficiencies obtained with the two nozzles were comparable for blade-jet speed ratios of less than 0.260. For blade-jet speed ratios exceeding this value, nozzle K yielded slightly higher efficiencies. The maximum blade efficiency of 0.569 was obtained with nozzle K at a pressure ratio of 8 and a blade-jet speed ratio of 0.295. At design speed and pressure ratio, nozzle K yielded a maximum blade efficiency of 0.534, an increase of 0.031 over that obtained with nozzle J. When the blade efficiencies of the two nozzles were compared with those of four other nozzles previously investigated, the maximum difference for the six nozzles with this rotor was 0.050. From, this comparison, no specific effect of nozzles size or shape on over-all performance was discernible.

  18. Material development for fan blade containment casing

    NASA Astrophysics Data System (ADS)

    McMillan, A.

    2008-03-01

    This paper describes the physics reasoning and the engineering development process for the structured material system adopted for the containment system of the Trent 900 engine. This is the Rolls-Royce engine that powers the Airbus A380 double-decker aeroplane, which is on the point of entering service. The fan blade containment casing is the near cylindrical casing that surrounds the fan blades at the front of the engine. The fan blades provide the main part of the thrust of the engine; the power to the fan is provided through a shaft from the turbine. The fan is approximately three meters in diameter, with the tips of the blade travelling at a little over Mach speed. The purpose of the containment system is to catch and contain a blade in the extremely unlikely event of a part or whole blade becoming detached. This is known as a ''Fan Blade Off (FBO)'' event. The requirement is that no high-energy fragments should escape the containment system; this is essential to prevent damage to other engines or to the fuselage of the aircraft. Traditionally the containment system philosophy has been to provide a sufficiently thick solid metallic skin that the blade cannot penetrate. Obviously, this is heavy. A good choice of metal in this case is a highly ductile steel, which arrests the kinetic energy of the blade through plastic deformation, and possibly, a controlled amount of cracking. This is known as ''hard wall'' containment. More recently, to reduce weight, containment systems have incorporated a Kevlar fibre wrap. In this case, the thinner metallic wall provides some containment, which is backed up by the stretching of the Kevlar fibres. This is known as ''soft wall'' containment; but it suffers the disadvantage of requiring a large empty volume in the nacelle in to which to expand. For the Trent 900 engine, there was a requirement to make a substantial weight saving while still adopting a hard wall style of containment system. To achieve this, a hollow structured

  19. Comprehensive testing of Nedwind 12-Meter wind turbine blades at NREL

    SciTech Connect

    Larwood, S.; Musial, W.

    2000-03-13

    This paper describes the structural testing of two NedWind 25 12-m blades at the National Renewable Energy Laboratory (NREL). The tests were conducted under the Standards, Measurement and Testing (SMT) Program in conjunction with tests conducted by four European laboratories to develop a common database of blade testing methods. All of the laboratories tested duplicate copies of blades taken from series production. Blade properties, including weight, center of gravity, natural frequencies, stiffness, and damping, were determined. Static load tests were performed at 110% of the extreme design load for strain verification. NREL performed single-axis and two-axis fatigue tests using business-as-usual testing practices. The single-axis test combined equivalent life loading for the edge and flap spectra into a single resultant load. The two-axis test applied the edge and flap components independently at a phase angle of 90{degree}. Damage areas were observed at (1) the trailing edge, which cracked near the maximum chord; (2) between the steel root collar and the composite, where circumferential cracking was noted; and (3) along the top of the spar between the 2,500-mm and 4,200-mm stations, where a notable increase in acoustic emissions was detected. NREL observed that the onset of damage occurred earlier in the single-axis test.

  20. Field testing of linear individual pitch control on the two-bladed controls advanced research turbine

    SciTech Connect

    van Solingen, Edwin; Fleming, Paul A.; Scholbrock, Andrew; van Wingerden, Jan-Willem

    2015-04-17

    This paper presents the results of field tests using linear individual pitch control (LIPC) on the two-bladed Controls Advanced Research Turbine 2 (CART2) at the National Renewable Energy Laboratory (NREL). LIPC has recently been introduced as an alternative to the conventional individual pitch control (IPC) strategy for two-bladed wind turbines. The main advantage of LIPC over conventional IPC is that it requires, at most, only two feedback loops to potentially reduce the periodic blade loads. In previous work, LIPC was designed to implement blade pitch angles at a fixed frequency (e.g., the once-per-revolution (1P) frequency), which made it only applicable in above-rated wind turbine operating conditions. In this study, LIPC is extended to below-rated operating conditions by gain scheduling the controller on the rotor speed. With this extension, LIPC and conventional IPC are successfully applied to the NREL CART2 wind turbine. Lastly, the field-test results obtained during the measurement campaign indicate that LIPC significantly reduces the wind turbine loads for both below-rated and above-rated operation.

  1. Field testing of linear individual pitch control on the two-bladed controls advanced research turbine

    DOE PAGESBeta

    van Solingen, Edwin; Fleming, Paul A.; Scholbrock, Andrew; van Wingerden, Jan-Willem

    2015-04-17

    This paper presents the results of field tests using linear individual pitch control (LIPC) on the two-bladed Controls Advanced Research Turbine 2 (CART2) at the National Renewable Energy Laboratory (NREL). LIPC has recently been introduced as an alternative to the conventional individual pitch control (IPC) strategy for two-bladed wind turbines. The main advantage of LIPC over conventional IPC is that it requires, at most, only two feedback loops to potentially reduce the periodic blade loads. In previous work, LIPC was designed to implement blade pitch angles at a fixed frequency (e.g., the once-per-revolution (1P) frequency), which made it only applicablemore » in above-rated wind turbine operating conditions. In this study, LIPC is extended to below-rated operating conditions by gain scheduling the controller on the rotor speed. With this extension, LIPC and conventional IPC are successfully applied to the NREL CART2 wind turbine. Lastly, the field-test results obtained during the measurement campaign indicate that LIPC significantly reduces the wind turbine loads for both below-rated and above-rated operation.« less

  2. Influence of Reynolds Number on Multi-Objective Aerodynamic Design of a Wind Turbine Blade.

    PubMed

    Ge, Mingwei; Fang, Le; Tian, De

    2015-01-01

    At present, the radius of wind turbine rotors ranges from several meters to one hundred meters, or even more, which extends Reynolds number of the airfoil profile from the order of 105 to 107. Taking the blade for 3MW wind turbines as an example, the influence of Reynolds number on the aerodynamic design of a wind turbine blade is studied. To make the study more general, two kinds of multi-objective optimization are involved: one is based on the maximum power coefficient (CPopt) and the ultimate load, and the other is based on the ultimate load and the annual energy production (AEP). It is found that under the same configuration, the optimal design has a larger CPopt or AEP (CPopt//AEP) for the same ultimate load, or a smaller load for the same CPopt//AEP at higher Reynolds number. At a certain tip-speed ratio or ultimate load, the blade operating at higher Reynolds number should have a larger chord length and twist angle for the maximum Cpopt//AEP. If a wind turbine blade is designed by using an airfoil database with a mismatched Reynolds number from the actual one, both the load and Cpopt//AEP will be incorrectly estimated to some extent. In some cases, the assessment error attributed to Reynolds number is quite significant, which may bring unexpected risks to the earnings and safety of a wind power project. PMID:26528815

  3. Reflection plane tests of a wind turbine blade tip section with ailerons

    NASA Astrophysics Data System (ADS)

    Savino, J. M.; Nyland, T. W.; Birchenough, A. G.; Jordan, F. L.; Campbell, N. K.

    1985-08-01

    Tests were conducted in the NASA Langley 30 by 60 foot Wind Tunnel on a full scale 7.31 m (24 ft) long tip section of a wind turbine rotor blade. The blade tip section was built with ailerons on the trailing edge. The ailerons, which spanned a length of 6.1 m (20 ft), were designed so that two types could be evaluated: the plain and the balanced. The ailerons were hinged on the suction surface at the 0.62 X chord station behind the leading edge. The purpose of the tests was to measure the aerodynamic characteristics of the blade section for: an angle of attack range from 0 deg to 90 deg aileron deflections from 0 deg to -90 deg, and Reynolds numbers of 0.79 and 1.5 x 10 to the 6th power. These data were then used to determine which aileron configuration had the most desirable rotor control and aerodynamic braking characteristics. Tests were also run to determine the effects of vortex generators, leading edge roughness, and the gaps between the aileron sections on the lift, drag, and chordwise force coefficients of the blade tip section.

  4. Monitoring the rotation status of wind turbine blades using high-speed camera system

    NASA Astrophysics Data System (ADS)

    Zhang, Dongsheng; Chen, Jubing; Wang, Qiang; Li, Kai

    2013-06-01

    The measurement of the rotating object is of great significance in engineering applications. In this study, a high-speed dual camera system based on 3D digital image correlation has been developed in order to monitor the rotation status of the wind turbine blades. The system allows sequential images acquired at a rate of 500 frames per second (fps). An improved Newton-Raphson algorithm has been proposed which enables detection movement including large rotation and translation in subpixel precision. The simulation experiments showed that this algorithm is robust to identify the movement if the rotation angle is less than 16 degrees between the adjacent images. The subpixel precision is equivalent to the normal NR algorithm, i.e.0.01 pixels in displacement. As a laboratory research, the high speed camera system was used to measure the movement of the wind turbine model which was driven by an electric fan. In the experiment, the image acquisition rate was set at 387 fps and the cameras were calibrated according to Zhang's method. The blade was coated with randomly distributed speckles and 7 locations in the blade along the radial direction were selected. The displacement components of these 7 locations were measured with the proposed method. Conclusion is drawn that the proposed DIC algorithm is suitable for large rotation detection, and the high-speed dual camera system is a promising, economic method in health diagnose of wind turbine blades.

  5. Reflection plane tests of a wind turbine blade tip section with ailerons

    NASA Technical Reports Server (NTRS)

    Savino, J. M.; Nyland, T. W.; Birchenough, A. G.; Jordan, F. L.; Campbell, N. K.

    1985-01-01

    Tests were conducted in the NASA Langley 30 by 60 foot Wind Tunnel on a full scale 7.31 m (24 ft) long tip section of a wind turbine rotor blade. The blade tip section was built with ailerons on the trailing edge. The ailerons, which spanned a length of 6.1 m (20 ft), were designed so that two types could be evaluated: the plain and the balanced. The ailerons were hinged on the suction surface at the 0.62 X chord station behind the leading edge. The purpose of the tests was to measure the aerodynamic characteristics of the blade section for: an angle of attack range from 0 deg to 90 deg aileron deflections from 0 deg to -90 deg, and Reynolds numbers of 0.79 and 1.5 x 10 to the 6th power. These data were then used to determine which aileron configuration had the most desirable rotor control and aerodynamic braking characteristics. Tests were also run to determine the effects of vortex generators, leading edge roughness, and the gaps between the aileron sections on the lift, drag, and chordwise force coefficients of the blade tip section.

  6. Calculation of three-dimensional boundary layers on rotor blades using integral methods

    SciTech Connect

    Karimipanah, M.T.; Olsson, E. )

    1993-04-01

    The important effects of rotation and compressibility on rotor blade boundary layers are theoretically investigated. The calculations are based on the momentum integral method and results from calculations of a transonic compressor rotor are presented. Influence of rotation is shown by comparing the incompressible rotating flow with the stationary one. Influence of compressibility is shown by comparing the compressible rotating flow with the incompressible rotating one. Two computer codes for three-dimensional laminar and turbulent boundary layers, originally developed by SSPA Maritime Consulting AB, have been further developed by introducing rotation and compressibility terms into the boundary layer equations. The effect of rotation and compressibility on the transition have been studied. The Coriolis and centrifugal forces that contribute to the development of the boundary layers and influence its behavior generate crosswise flow inside the blade boundary layers, the magnitude of which depends upon the angular velocity of the rotor and the rotor geometry. The calculations show the influence of rotation and compressibility on the boundary layer parameters. Momentum thickness and shape factor increase with increasing rotation and decrease when compressible flow is taken into account. For skin friction such effects have inverse influences. The different boundary layer parameters behave similarly on the suction and pressure sides with the exception of the crossflow angle, the crosswise momentum thickness, and the skin friction factor. The codes use a nearly orthogonal streamline coordinate system, which is fixed to the blade surface and rotates with the blade.

  7. Stall behavior of a scaled three-dimensional wind turbine blade

    NASA Astrophysics Data System (ADS)

    Mulleners, Karen; Melius, Matthew; Cal, Raul Bayoan

    2014-11-01

    The power generation of a wind turbine is influenced by many factors including the unsteady incoming flow characteristics, pitch regulation, and the geometry of the various turbine components. Within the framework of maximizing energy extraction, it is important to understand and tailor the aerodynamics of a wind turbine. In the interest of seeking further understanding into the complex flow over wind turbine blades, a three-dimensional scaled blade model has been designed and manufactured to be dynamically similar to a rotating full-scale NREL 5MW wind turbine blade. A wind tunnel experiment has been carried out in the 2.2 m × 1.8 m cross-section closed loop wind tunnel at DLR in Göttingen by means of time-resolved stereoscopic PIV. An extensive coherent structure analysis of the time-resolved velocity field over the suction side of the blade was performed to study stall characteristics under a geometrically induced pressure gradient. In particular, the radial extent and propagation of stalled flow regions were characterized for various static angles of attack.

  8. Influence of Reynolds Number on Multi-Objective Aerodynamic Design of a Wind Turbine Blade

    PubMed Central

    Ge, Mingwei; Fang, Le; Tian, De

    2015-01-01

    At present, the radius of wind turbine rotors ranges from several meters to one hundred meters, or even more, which extends Reynolds number of the airfoil profile from the order of 105 to 107. Taking the blade for 3MW wind turbines as an example, the influence of Reynolds number on the aerodynamic design of a wind turbine blade is studied. To make the study more general, two kinds of multi-objective optimization are involved: one is based on the maximum power coefficient (CPopt) and the ultimate load, and the other is based on the ultimate load and the annual energy production (AEP). It is found that under the same configuration, the optimal design has a larger CPopt or AEP (CPopt//AEP) for the same ultimate load, or a smaller load for the same CPopt//AEP at higher Reynolds number. At a certain tip-speed ratio or ultimate load, the blade operating at higher Reynolds number should have a larger chord length and twist angle for the maximum Cpopt//AEP. If a wind turbine blade is designed by using an airfoil database with a mismatched Reynolds number from the actual one, both the load and Cpopt//AEP will be incorrectly estimated to some extent. In some cases, the assessment error attributed to Reynolds number is quite significant, which may bring unexpected risks to the earnings and safety of a wind power project. PMID:26528815

  9. Vacuum plasma coatings for turbine blades

    NASA Technical Reports Server (NTRS)

    Holmes, R. R.

    1985-01-01

    Turbine blades, vacuum plasma spray coated with NiCrAlY, CoCrAlY or NiCrAlY/Cr2O3, were evaluated and rated superior to standard space shuttle main engine (SSME) coated blades. Ratings were based primarily on 25 thermal cycles in the MSFC Burner Rig Tester, cycling between 1700 F (gaseous H2) and -423 F (liquid H2). These tests showed no spalling on blades with improved vacuum plasma coatings, while standard blades spalled. Thermal barrier coatings of ZrO2, while superior to standard coatings, lacked the overall performance desired. Fatigue and tensile specimens, machined from MAR-M-246(Hf) test bars identical to the blades were vacuum plasma spray coated, diffusion bond treated, and tested to qualify the vacuum plasma spray process for flight hardware testing and application. While NiCrAlY/Cr2O3 offers significant improvement over standard coatings in durability and thermal protection, studies continue with an objective to develop coatings offering even greater improvements.

  10. 3X-100 blade field test.

    SciTech Connect

    Zayas, Jose R.; Johnson, Wesley D.

    2008-03-01

    In support of a Work-For-Other (WFO) agreement between the Wind Energy Technology Department at Sandia National Laboratories and 3TEX, one of the three Micon 65/13M wind turbines at the USDA Agriculture Research Service (ARS) center in Bushland, Texas, has been used to test a set of 9 meter wind turbine blades, manufactured by TPI composites using the 3TEX carbon material for the spar cap. Data collected from the test has been analyzed to evaluate both the aerodynamic performance and the structural response from the blades. The blades aerodynamic and structural performance, the meteorological inflow and the wind turbine structural response has been monitored with an array of 57 instruments: 15 to characterize the blades, 13 to characterize inflow, and 15 to characterize the time-varying state of the turbine. For the test, data was sampled at a rate of 40 Hz using the ATLAS II (Accurate GPS Time-Linked Data Acquisition System) data acquisition system. The system features a time-synchronized continuous data stream and telemetered data from the turbine rotor. This paper documents the instruments and infrastructure that have been developed to monitor these blades, turbines and inflow, as well as both modeling and field testing results.

  11. Structural health monitoring of wind turbine blades

    NASA Astrophysics Data System (ADS)

    Rumsey, Mark A.; Paquette, Joshua A.

    2008-03-01

    As electric utility wind turbines increase in size, and correspondingly, increase in initial capital investment cost, there is an increasing need to monitor the health of the structure. Acquiring an early indication of structural or mechanical problems allows operators to better plan for maintenance, possibly operate the machine in a de-rated condition rather than taking the unit off-line, or in the case of an emergency, shut the machine down to avoid further damage. This paper describes several promising structural health monitoring (SHM) techniques that were recently exercised during a fatigue test of a 9 meter glass-epoxy and carbon-epoxy wind turbine blade. The SHM systems were implemented by teams from NASA Kennedy Space Center, Purdue University and Virginia Tech. A commercial off-the-shelf acoustic emission (AE) NDT system gathered blade AE data throughout the test. At a fatigue load cycle rate around 1.2 Hertz, and after more than 4,000,000 fatigue cycles, the blade was diagnostically and visibly failing at the out-board blade spar-cap termination point at 4.5 meters. For safety reasons, the test was stopped just before the blade completely failed. This paper provides an overview of the SHM and NDT system setups and some current test results.

  12. Turbine blade cooling using Coulomb repulsion

    NASA Astrophysics Data System (ADS)

    Breidenthal, Robert; Colannino, Joseph; Dees, John; Goodson, David; Krichtafovitch, Igor; Prevo, Tracy

    2012-11-01

    Video photography and thermocouples reveal the effect of an electric field on the flow around a stationary, idealized turbine blade downstream of a combustor. The hot products of combustion naturally include positive ions. When the blade is an electrode and elevated to a positive potential, it tends to attract the free electrons and repel the positive ions. Due to their lower mass, the light electrons are rapidly swept toward the blade, while the positive ions are repelled. As they collide with the neutrals in the hot gas, the positive ions transfer their momentum so that a Coulomb body force is exerted on the hot gas. Cool, compressed air is injected out of the stationary blade near its leading edge to form a layer of film cooling. In contrast to the hot combustion products, the cool air is not ionized. At the interface between the hot gas and the cool air, the Coulomb repulsion force acts on the former but not the latter, analogous to gravity at a stratified interface. An effective Richardson number representing the ratio of potential to kinetic energy characterizes the topography of the interface. When the electric field is turned on, the repulsion of the hot gas from the idealized blade is evident in video recordings and thermocouple measurements.

  13. Piezoelectric actuation of helicopter rotor blades

    NASA Astrophysics Data System (ADS)

    Lieven, Nicholas A. J.

    2001-07-01

    The work presented in this paper is concerned with the application of embedded piezo-electric actuators in model helicopter rotor blades. The paper outlines techniques to define the optimal location of actuators to excite particular modes of vibration whilst the blade is rotating. Using composite blades the distribution of strain energy is defined using a Finite Element model with imposed rotor-dynamic and aerodynamics loads. The loads are specified through strip theory to determine the position of maximum bending moment and thus the optimal location of the embedded actuators. The effectiveness of the technique is demonstrated on a 1/4 scale fixed cyclic pitch rotor head. Measurement of the blade displacement is achieved by using strain gauges. In addition a redundant piezo-electric actuator is used to measure the blades' response characteristics. The addition of piezo-electric devices in this application has been shown to exhibit adverse aeroelastic effects, such as counter mass balancing and increased drag. Methods to minimise these effects are suggested. The outcome of the paper is a method for defining the location and orientation of piezo-electric devices in rotor-dynamic applications.

  14. Elastically tailored composite rotor blades for stall alleviation and vibration reduction

    NASA Astrophysics Data System (ADS)

    Floros, Matthew William

    An aeroelastic analysis has been developed to study the effects of elastic couplings on blade response, loads, and dynamic stall. Low and high speed conditions are examined at high thrust and cruise-level thrust for both hingeless and articulated rotor configurations. The blade cross-sectional model is based on Vlasov theory for multi-cell closed sections with thick walls. The structural model includes non-classical effects of transverse shear, torsion-related warping, and two-dimensional inplane elasticity. For the aeroelastic analysis, the blade is modeled as an elastic beam undergoing deflections in flap, lag, and torsion. The blade governing equations are approximated by a finite element in space model. A twelve degree of freedom specialized finite element is employed in the structural model which accounts for torsion-related warping. The analysis includes both a quasisteady and a time-domain unsteady aerodynamic model including the effects of non-linear separation and dynamic stall. The nonlinear periodic response is calculated through a finite element in time procedure with displacement and velocity continuous elements. The blade and hub loads are calculated using the force summation method and the reaction force method. The two loads calculation methods are compared for articulated and hingeless rotor configurations. The reaction force method is shown to more accurately predict blade bending moments in articulated rotors. The blade is modeled as a NACA airfoil section consisting of a D-spar and skin. Elastic couplings are introduced by anisotropy of plies in the D-spar to produce pitch-flap couplings. Results indicate that by coupling elastic twist to the second flap mode, the angle of attack on the retreating side of the rotor disk can be reduced up to two degrees, resulting in a significant reduction in blade stall for both articulated and hingeless rotors. Sensitivity studies are conducted to determine the effects of flap frequency on the induced twist

  15. Solar angle reference manual

    SciTech Connect

    Sibson, R.

    1983-01-01

    The introduction is the only text in the volume; the rest of the book contains easy-to-use graphical methods for building design and construction using solar energy. Isogonic charts and solar angle diagrams are included. Isogonic charts. Solar angle diagrams.

  16. Reading Angles in Maps

    ERIC Educational Resources Information Center

    Izard, Véronique; O'Donnell, Evan; Spelke, Elizabeth S.

    2014-01-01

    Preschool children can navigate by simple geometric maps of the environment, but the nature of the geometric relations they use in map reading remains unclear. Here, children were tested specifically on their sensitivity to angle. Forty-eight children (age 47:15-53:30 months) were presented with fragments of geometric maps, in which angle sections…

  17. Adjustable reed for weaving net-shaped tailored fabrics

    NASA Technical Reports Server (NTRS)

    Farley, Gary L. (Inventor)

    1995-01-01

    An apparatus and method for forming woven fabrics through the use of an adjustable reed. The adjustable reed has multiple groups of reed wires that guide the warp yarns. The groups of reed wires move on reed rails parallel to the warp direction. In addition, rail expanders permit the space between the reed wires to be modified and telescoping rods attached to the rail sliders can be turned to permit the reed wires to be skewed to alter the fill yarn angle. These adjustments to the reed permit simultaneous variation of fill yarn angles and fabric widths and allow these variations to be made during fabrication, without the need to halt production.

  18. Piezoelectric Vibration Damping Study for Rotating Composite Fan Blades

    NASA Technical Reports Server (NTRS)

    Min, James B.; Duffy, Kirsten P.; Choi, Benjamin B.; Provenza, Andrew J.; Kray, Nicholas

    2012-01-01

    Resonant vibrations of aircraft engine blades cause blade fatigue problems in engines, which can lead to thicker and aerodynamically lower performing blade designs, increasing engine weight, fuel burn, and maintenance costs. In order to mitigate undesirable blade vibration levels, active piezoelectric vibration control has been investigated, potentially enabling thinner blade designs for higher performing blades and minimizing blade fatigue problems. While the piezoelectric damping idea has been investigated by other researchers over the years, very little study has been done including rotational effects. The present study attempts to fill this void. The particular objectives of this study were: (a) to develop and analyze a multiphysics piezoelectric finite element composite blade model for harmonic forced vibration response analysis coupled with a tuned RLC circuit for rotating engine blade conditions, (b) to validate a numerical model with experimental test data, and (c) to achieve a cost-effective numerical modeling capability which enables simulation of rotating blades within the NASA Glenn Research Center (GRC) Dynamic Spin Rig Facility. A numerical and experimental study for rotating piezoelectric composite subscale fan blades was performed. It was also proved that the proposed numerical method is feasible and effective when applied to the rotating blade base excitation model. The experimental test and multiphysics finite element modeling technique described in this paper show that piezoelectric vibration damping can significantly reduce vibrations of aircraft engine composite fan blades.

  19. A newer technique to program a semi adjustable articulator

    PubMed Central

    Venkateshwaran, R.; Karthigeyan, Suma; Manoharan, P. S.; Konchada, Jagadish; Ramaswamy, Manikandan; Bhuminathan

    2014-01-01

    Introduction: The difficulty in reproducing accurate angle of condylar guidance in semi-adjustable articulators. Purpose: The purpose of this study was to determine the correlation between the angle of horizontal condylar inclination obtained on a semi-adjustable articulator and the corresponding angle traced on a temporomandibular joint (TMJ) radiograph in completely edentulous subject. Materials and Methods: The horizontal condylar inclination angle was obtained in a semi-adjustable articulator by means of height tracer (extra oral tracing device) and interocclusal records to program the articulator in 21 subjects. TMJ radiograph were recorded by the same operator with same orthopantomogram (OPG) machine (planmeca). Tracings of inclines of articular eminence on the radiograph were compared with the angle obtained on a semi-adjustable articulator. Each measurement was made using manual methods of measuring angle. The results were subjected to the Pearson correlation statistical analysis (α =0.01). Results: The outline of the articular eminence in a TMJ tomogram radiographic image was identified and traced. A significant correlation was found between the horizontal condylar inclination on a semi-adjustable and the corresponding TMJ tomogram radiographic image for both right (R = 0.789; P = 0.001) and left (i = 0.747; P = 0.004) sides. Conclusion: The articular eminence traced on a TMJ tomogram image represents the horizontal condylar inclination with a mean difference of 5° in 21 subjects evaluated. PMID:25210356

  20. Microtextured Surfaces for Turbine Blade Impingement Cooling

    NASA Technical Reports Server (NTRS)

    Fryer, Jack

    2014-01-01

    Gas turbine engine technology is constantly challenged to operate at higher combustor outlet temperatures. In a modern gas turbine engine, these temperatures can exceed the blade and disk material limits by 600 F or more, necessitating both internal and film cooling schemes in addition to the use of thermal barrier coatings. Internal convective cooling is inadequate in many blade locations, and both internal and film cooling approaches can lead to significant performance penalties in the engine. Micro Cooling Concepts, Inc., has developed a turbine blade cooling concept that provides enhanced internal impingement cooling effectiveness via the use of microstructured impingement surfaces. These surfaces significantly increase the cooling capability of the impinging flow, as compared to a conventional untextured surface. This approach can be combined with microchannel cooling and external film cooling to tailor the cooling capability per the external heating profile. The cooling system then can be optimized to minimize impact on engine performance.