Academic literature on the topic 'Blade profile pressure'
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Journal articles on the topic "Blade profile pressure"
1
Curtis, E. M., H. P. Hodson, M. R. Banieghbal, J. D. Denton, R. J. Howell, and N. W. Harvey. "Development of Blade Profiles for Low-Pressure Turbine Applications." Journal of Turbomachinery 119, no. 3 (July 1, 1997): 531–38. http://dx.doi.org/10.1115/1.2841154.
Full textAbstract:
This paper describes a program of work, largely experimental, which was undertaken with the objective of developing an improved blade profile for the low-pressure turbine in aero-engine applications. Preliminary experiments were conducted using a novel technique. An existing cascade of datum blades was modified to enable the pressure distribution on the suction surface of one of the blades to be altered. Various means, such as shaped inserts, an adjustable flap at the trailing edge, and changing stagger were employed to change the geometry of the passage. These experiments provided boundary layer and lift data for a wide range of suction surface pressure distributions. The data were then used as a guide for the development of new blade profiles. The new blade profiles were then investigated in a low-speed cascade that included a set of moving bars upstream of the cascade of blades to simulate the effect of the incoming wakes from the previous blade row in a multistage turbine environment. Results are presented for two improved profiles that are compared with a datum representative of current practice. The experimental results include loss measurements by wake traverse, surface pressure distributions, and boundary layer measurements. The cascades were operated over a Reynolds number range from 0.7 × 105 to 4.0 × 105. The first profile is a “laminar flow” design that was intended to improve the efficiency at the same loading as the datum. The other is a more highly loaded blade profile intended to permit a reduction in blade numbers. The more highly loaded profile is the most promising candidate for inclusion in future designs. It enables blade numbers to be reduced by 20 percent, without incurring any efficiency penalty. The results also indicate that unsteady effects must be taken into consideration when selecting a blade profile for the low-pressure turbine.
2
Mailach, Ronald, and Konrad Vogeler. "Rotor-Stator Interactions in a Four-Stage Low-Speed Axial Compressor—Part I: Unsteady Profile Pressures and the Effect of Clocking." Journal of Turbomachinery 126, no. 4 (October 1, 2004): 507–18. http://dx.doi.org/10.1115/1.1791641.
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This two-part paper presents detailed experimental investigations of unsteady aerodynamic blade row interactions in the four-stage Low-Speed Research Compressor of Dresden. In part I of the paper the unsteady profile pressure distributions for the nominal setup of the compressor are discussed. Furthermore, the effect of blade row clocking on the unsteady profile pressures is investigated. Part II deals with the unsteady aerodynamic blade forces, which are calculated from the measured profile pressure distributions. The unsteady pressure distributions were analyzed in the first, a middle and the last compressor stage both on the rotor and stator blades. The measurements were carried out on pressure side and suction side at midspan. Several operating points were investigated. A complex behavior of the unsteady profile pressures can be observed, resulting from the superimposed influences of the wakes and the potential effects of several up- and downstream blade rows of the four-stage compressor. The profile pressure changes nearly simultaneously along the blade chord if a disturbance arrives at the leading edge or the trailing edge of the blade. Thus the unsteady profile pressure distribution is nearly independent of the convective wake propagation within the blade passage. A phase shift of the reaction of the blade to the disturbance on the pressure and suction side is observed. In addition, clocking investigations were carried out to distinguish between the different periodic influences from the surrounding blade rows. For this reason the unsteady profile pressure distribution on rotor 3 was measured, while stators 1–4 were separately traversed stepwise in the circumferential direction. Thus the wake and potential effects of the up- and downstream blade rows on the unsteady profile pressure could clearly be distinguished and quantified.
3
Spasic, Zivan, Sasa Milanovic, Vanja Sustersic, and Boban Nikolic. "Low-pressure reversible axial fan with straight profile blades and relatively high efficiency." Thermal Science 16, suppl. 2 (2012): 593–603. http://dx.doi.org/10.2298/tsci120503194s.
Full textAbstract:
The paper presents the design and operating characteristics of a model of reversible axial fan with only one impeller, whose reversibility is achieved by changing the direction of rotation. The fan is designed for the purpose of providing alternating air circulation in wood dryers in order to reduce the consumption of electricity for the fan and increase energy efficiency of the entire dryer. To satisfy the reversibility of flow, the shape of the blade profile is symmetrical along the longitudinal and transversal axes of the profile. The fan is designed with equal specific work of all elementary stages, using the method of lift forces. The impeller blades have straight mean line profiles. The shape of the blade profile was adopted after the numerical simulations were carried out and high efficiency was achieved. Based on the calculation and conducted numerical simulations, a physical model of the fan was created and tested on a standard test rig, with air loading at the suction side of the fan. The operating characteristics are shown for different blade angles. The obtained maximum efficiency was around 0.65, which represents a rather high value for axial fans with straight profile blades.
4
Mailach, Ronald, and Konrad Vogeler. "Aerodynamic Blade Row Interactions in an Axial Compressor—Part II: Unsteady Profile Pressure Distribution and Blade Forces." Journal of Turbomachinery 126, no. 1 (January 1, 2004): 45–51. http://dx.doi.org/10.1115/1.1649742.
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This two-part paper presents experimental investigations of unsteady aerodynamic blade row interactions in the first stage of the four-stage low-speed research compressor of Dresden. Both the unsteady boundary layer development and the unsteady pressure distribution of the stator blades are investigated for several operating points. The measurements were carried out on pressure side and suction side at midspan. In Part II of the paper the investigations of the unsteady pressure distribution on the stator blades are presented. The experiments were carried out using piezoresistive miniature pressure sensors, which are embedded into the pressure and suction side surface of a single blade. The unsteady pressure distribution on the blade is analyzed for the design point and an operating point near the stability limit. The investigations show that it is strongly influenced by both the incoming wakes and the potential flow field of the downstream rotor blade row. If a disturbance arrives the leading edge or the trailing edge of the blade the pressure changes nearly simultaneously along the blade chord. Thus the unsteady profile pressure distribution is independent of the wake propagation within the blade passage. A phase shift of the reaction on pressure and suction side is observed. The unsteady response of the boundary layer and the profile pressure distribution is compared. Based on the unsteady pressure distribution the unsteady pressure forces of the blades are calculated and discussed.
5
Xu, C., and R. S. Amano. "Meridional Considerations of the Centrifugal Compressor Development." International Journal of Rotating Machinery 2012 (2012): 1–11. http://dx.doi.org/10.1155/2012/518381.
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Centrifugal compressor developments are interested in using optimization procedures that enable compressor high efficiency and wide operating ranges. Recently, high pressure ratio and efficiency of the centrifugal compressors require impeller design to pay attention to both the blade angle distribution and the meridional profile. The geometry of the blades and the meridional profile are very important contributions of compressor performance and structure reliability. This paper presents some recent studies of meridional impacts of the compressor. Studies indicated that the meridional profiles of the impeller impact the overall compressor efficiency and pressure ratio at the same rotational speed. Proper meridional profiles can improve the compressor efficiency and increase the overall pressure ratio at the same blade back curvature.
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Pullan, Graham, and Neil W. Harvey. "Influence of Sweep on Axial Flow Turbine Aerodynamics at Midspan." Journal of Turbomachinery 129, no. 3 (July 14, 2006): 591–98. http://dx.doi.org/10.1115/1.2472397.
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Sweep, when the stacking axis of the blade is not perpendicular to the axisymmetric streamsurface in the meridional view, is often an unavoidable feature of turbine design. Although a high aspect ratio swept blade can be designed to achieve the same pressure distribution as an unswept design, this paper shows that the swept blade will inevitably have a higher profile loss. A modified Zweifel loading parameter, taking sweep into account, is first derived. If this loading coefficient is held constant, it is shown that sweep reduces the required pitch-to-chord ratio and thus increases the wetted area of the blades. Assuming fully turbulent boundary layers and a constant dissipation coefficient, the effect of sweep on profile loss is then estimated. A combination of increased blade area and a raised pressure surface velocity means that the profile loss rises with increasing sweep. The theory is then validated using experimental results from two linear cascade tests of highly loaded blade profiles of the type found in low-pressure aeroengine turbines: one cascade is unswept, the other has 45deg of sweep. The swept cascade is designed to perform the same duty with the same loading coefficient and pressure distribution as the unswept case. The measurements show that the simple method used to estimate the change in profile loss due to sweep is sufficiently accurate to be a useful aid in turbine design.
7
Gamal, Ahmed M., Bugra H. Ertas, and John M. Vance. "High-Pressure Pocket Damper Seals: Leakage Rates and Cavity Pressures." Journal of Turbomachinery 129, no. 4 (September 3, 2006): 826–34. http://dx.doi.org/10.1115/1.2720871.
Full textAbstract:
The turbomachinery component of interest in this paper, the pocket damper seal, has the dual purpose of limiting leakage and providing an additional source of damping at the seal location. The rotordynamic coefficients of these seals (primarily the direct stiffness and damping) are highly dependent on the leakage rates through the seals and the pressures in the seals’ cavities. This paper presents both numerical predictions and experimentally obtained results for the leakage and the cavity pressures of pocket damper seals operating at high pressures. The seals were tested with air, at pressures up to 1000psi(6.92MPa), as the working fluid. Earlier flow-prediction models were modified and used to obtain theoretical reference values for both mass flow rates and pressures. Leakage and static pressure measurements on straight-through and diverging-clearance configurations of eight-bladed and twelve-bladed seals were used for code validation and for calculation of seal discharge coefficients. Higher than expected leakage rates were measured in the case of the twelve-bladed seal, while the leakage rates for the eight-bladed seals were predicted with reasonable accuracy. Differences in the axial pitch lengths of the cavities and the blade profiles of the seals are used to explain the discrepancy in the case of the twelve-bladed seal. The analysis code used also predicted the static cavity pressures reasonably well. Tests conducted on a six-bladed pocket damper seal to further investigate the effect of blade profile supported the results of the eight-bladed and twelve-bladed seal tests and matched theoretical predictions with satisfactory accuracy.
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Ozoliņš, Ilmārs, Ēriks Ozoliņš, and Valērija Fedotova. "Development of a Method for Calculating the Working Blade Stress Profile of the Aviation Gas Turbine Engine for Student Training." Transport and Aerospace Engineering 6, no. 1 (November 1, 2018): 55–66. http://dx.doi.org/10.2478/tae-2018-0007.
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Abstract The paper presents a method of calculation gas turbine engine compressor or low-pressure turbine working blade profile for student training. This method of calculation was prepared for working blades with and without shroud shelves. This method provides a calculation technique to reduce the load on blade root part and the determination of blade profile stress distribution and the comparison before and after reduction of load.
9
Wei, Yikun, Cunlie Ying, Jun Xu, Wenbin Cao, Zhengdao Wang, and Zuchao Zhu. "Effects of Single-arc Blade Profile Length on the Performance of a Forward Multiblade Fan." Processes 7, no. 9 (September 17, 2019): 629. http://dx.doi.org/10.3390/pr7090629.
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The effects of single-arc blade profile length on the performance of a forward multiblade fan are investigated in this paper by computational fluid dynamics and experimental measurement. The present work emphasizes that the use of a properly reduced blade inlet angle (β1A) and properly improved blade outlet angle (β2A) is to increase the length blade profile, which suggests a good physical understanding of internal complex flow characteristics and the aerodynamic performance of the fan. Numerical results indicate that the gradient of the absolute velocity among the blades in model-L (reducing the blade inlet angle and improving blade outlet angle) is clearly lower than that of the baseline model and model-S (improving the blade inlet angle and reducing blade outlet angle), where a number of secondary flows arise on the exit surface of baseline model and model-S. However, no secondary flow occurs in model-L, and the flow loss at the exit surface of the volute (scroll-shaped flow patterns) for model-L is obviously lower than that of the baseline model at the design point. The comparison of the test results further shows that to improve the blade profile length is to increase the static pressure and the efficiency of the static pressure, since the improved static pressure of the model-L rises as much as 22.5 Pa and 26.2%, and the improved static pressure efficiency of the model-L rises as much as 5 % at the design flow rates. It is further indicated that increasing the blade working area provides significant physical insight into increasing the static pressure, total pressure, the efficiency of the static pressure and the total pressure efficiency.
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Howell, R. J., and K. M. Roman. "Loss reduction on ultra high lift low-pressure turbine blades using selective roughness and wake unsteadiness." Aeronautical Journal 111, no. 1118 (April 2007): 257–66. http://dx.doi.org/10.1017/s0001924000004504.
Full textAbstract:
This paper describes how it is possible to reduce the profile losses on ultra high lift low pressure (LP) turbine blade profiles with the application of selected surface roughness and wake unsteadiness. Over the past several years, an understanding of wake interactions with the suction surface boundary layer on LP turbines has allowed the design of blades with ever increasing levels of lift. Under steady flow conditions, ultra high lift profiles would have large (and possibly open) separation bubbles present on the suction side which result from the very high diffusion levels. The separation bubble losses produced by it are reduced when unsteady wake flows are present. However, LP turbine blades have now reached a level of loading and diffusion where profile losses can no longer be controlled by wake unsteadiness alone. The ultra high lift profiles investigated here were created by attaching a flap to the trailing edge of another blade in a linear cascade — the so called flap-test technique. The experimental set-up used in this investigation allows for the simulation of upstream wakes by using a moving bar system. Hotwire and hotfilm measurements were used to obtain information about the boundary-layer state on the suction surface of the blade as it evolved in time. Measurements were taken at a Reynolds numbers ranging between 100,000 and 210,000. Two types of ultra high lift profile were investigated; ultra high lift and extended ultra high lift, where the latter has 25% greater back surface diffusion as well as a 12% increase in lift compared to the former. Results revealed that distributed roughness reduced the size of the separation bubble with steady flow. When wakes were present, the distributed roughness amplified disturbances in the boundary layer allowing for more rapid wake induced transition to take place, which tended to eliminate the separation bubble under the wake. The extended ultra high lift profile generated only slightly higher losses than the original ultra high lift profile, but more importantly it generated 12% greater lift.
Dissertations / Theses on the topic "Blade profile pressure"
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Mukherjee, Sriparna. "Evolution of microstructure and residual stress in disc-shape EB-PVD thermal barrier coatings and temperature profile of high pressure turbine blade." Master's thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4989.
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A detailed understanding of failure mechanisms in thermal barrier coatings (TBCs) can help develop reliable and durable TBCs for advanced gas turbine engines. One of the characteristics of failure in electron beam physical vapor deposited (EB-PVD) TBCs is the development of instability, named rumpling, at the interface between (Ni, Pt)Al bond coat and thermally grown oxide (TGO). In this study, thermal cycling at 1100[degrees]C with 1 hr dwell time was carried out on 25.4mm disc specimens of TBCs that consisted of EB-PVD coated ZrO[sub2]-7wt.%Y[sub2]O[sub3], (Pt,Ni)Al bond coat, and CMSX-4 Ni-based superalloy. At specific fraction of lifetime, TBCs were examined by electron microscopy and photostimulated luminescence (PL). Changes in the average compressive residual stress of the TGO determined by PL and the magnitude of rumpling, determined by tortuosity from quantitative microstructural analyses, were examined with respect to the furnace thermal cyclic lifetime and microstructural evolution of TBCs. The combination of elastic strain energy within the TGO and interfacial energy at the interface between the TGO and the bond coat was defined as the TGO energy, and its variation with cyclic oxidation time was found to remain approximately constant ~135J/m[super2] during thermal cycling from 10% to 80% thermal cyclic lifetime. Parametric study at ~135J/m[super2] was performed and variation in residual stress with rumpling for different oxide scale thicknesses was examined. This study showed that the contribution of rumpling in residual stress relaxation decreased with an increase in TGO thickness. High pressure turbine blades serviced for 2843 hours and in the as coated form were also examined using electron microscopy and photostimulated luminescence. The difference in residual stress values obtained using PL on the suction and pressure sides of as-coated turbine blade were discussed.; The presence of a thick layer of deposit on the serviced blade gave signals from stress free alpha]-Al[sub2]O[sub3] in the deposit, not from the TGO. The TGO growth constant data from the disc-shape TBCs, thermally cycled at 1100??C, and studies by other authors at different temperatures but on similar EB-PVD coated TBCs with (Pt, Ni)Al bond coat and CMSX-4 Ni- based superalloy were used to determine the temperature profile at the YSZ/bond coat interface. The interfacial temperature profiles of the serviced blade and the YSZ thickness profile were compared to document the variable temperature exposure at the leading edge, trailing edge, suction and the pressure side.ID: 030423389; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.)--University of Central Florida, 2011.; Includes bibliographical references (p. 90-92).
M.S.
Masters
Mechanical, Materials, and Aerospace Engineering
Engineering and Computer Science
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Vondra, Marek. "Měření na turbínové mříži." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231810.
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The Aim of this Diploma thesis is the measurement on turbine cascade. The first part is focused on measurement of the flow characteristics of the turbine cascade using a three–hole pressure probe. The second part includes the blade profile pressure measurement. Both measurements are performed both experimentally and by computer simulation in Ansys and the results are compared. Part of the work is also file containining the computer simulation, which was carried out in CFX program.
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Mathison, Randall Melson. "Experimental and Computational Investigation of Inlet Temperature Profile and Cooling Effects on a One and One-Half Stage High-Pressure Turbine Operating at Design-Corrected Conditions." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1250281163.
Full textBook chapters on the topic "Blade profile pressure"
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Coeto, Juan Bernardo Sosa, Gustavo Urquiza Beltrán, Juan Carlos García Castrejon, Laura Lilia Castro Gómez, and Marcelo Reggio. "Optimization of the Impeller and Diffuser of Hydraulic Submersible Pump using Computational Fluid Dynamics and Artificial Neural Networks." In Logistics Management and Optimization through Hybrid Artificial Intelligence Systems, 456–74. IGI Global, 2012. http://dx.doi.org/10.4018/978-1-4666-0297-7.ch018.
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Overall performance of hydraulic submersible pump is strongly linked to its geometry, impeller speed and physical properties of the fluid to be pumped. During the design stage, given a fluid and an impeller speed, the pump blades profiles and the diffuser shape has to be determined in order to achieve maximum power and efficiency. Using Computational Fluid Dynamics (CFD) to calculate pressure and velocity fields, inside the diffuser and impeller of pump, represents a great advantage to find regions where the behavior of fluid dynamics could be adverse to the pump performance. Several trials can be run using CFD with different blade profiles and different shapes and dimensions of diffuser to calculate the effect of them over the pump performance, trying to find an optimum value. However the optimum impeller and diffuser would never be obtained using lonely CFD computations, by this means are necessary the application of Artificial Neural Networks, which was used to find a mathematical relation between these components (diffusers and blades) and the hydraulic head obtained by CFD calculations. In the present chapter artificial neural network algorithms are used in combinations with CFD computations to reach an optimum in the pumps performance.
Conference papers on the topic "Blade profile pressure"
1
Curtis, E. M., H. P. Hodson, M. R. Banieghbal, J. D. Denton, R. J. Howell, and N. W. Harvey. "Development of Blade Profiles for Low Pressure Turbine Applications." In ASME 1996 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/96-gt-358.
Full textAbstract:
This paper describes a programme of work, largely experimental, which was undertaken with the objective of developing an improved blade profile for the low-pressure turbine in aero-engine applications. Preliminary experiments were conducted using a novel technique. An existing cascade of datum blades was modified to enable the pressure distribution on the suction surface of one of the blades to be altered. Various means, such as shaped inserts, an adjustable flap at the trailing edge, and changing stagger were employed to change the geometry of the passage. These experiments provided boundary layer and lift data for a wide range of suction surface pressure distributions. The data was then used as a guide for the development of new blade profiles. The new blade profiles were then investigated in a low-speed cascade that included a set of moving bars upstream of the cascade of blades 10 simulate the effect of the incoming wakes from the previous blade row in a multistage turbine environment. Results are presented for two improved profiles that are compared with a datum representative of current practice. The experimental results include loss measurements by wake traverse, surface pressure distributions, and boundary layer measurements. The cascades were operated over a Reynolds Number range from 0.7 × 105 to 4.0 × 105. The first profile is a “laminar flow” design that was intended to improve the efficiency at the same loading as the datum. The other is a more highly loaded blade profile intended to permit a reduction in blade numbers. The more highly loaded profile is the most promising candidate for inclusion in future designs. It enables blade numbers to be reduced by 20%, without incurring any efficiency penalty. The results also indicate that unsteady effects must be taken into consideration when selecting a blade profile for the low-pressure turbine.
2
Britz, Marcus, Peter Jeschke, Oliver Brunn, and Thomas Polklas. "The Use of Air-Measured Profile Data for Application in a High Pressure Steam Turbine." In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63667.
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This paper investigates the validity of the current industrial procedure of measuring optimized blade profiles in a wind tunnel under air condition although they are applied in a steam turbine. Therefore, it is important to analyze the possibility of using air-measured profile data for optimizing steam turbine blades. To this end, experimental data is collected using the cylindrical datum blade of a steam turbine in a three-stage high pressure steam turbine and in an annular air cascade wind tunnel. Three-dimensional CFD simulations are separately performed for both setups and show a good agreement with the experimental data. The numerical simulations can therefore be assumed to represent the real flow conditions. Firstly, for analyzing aerodynamic transferability, two optimized profiles are measured in the annular air cascade wind tunnel at Reynolds number of 6 × 105. These profile sections are designed for high and intermediate pressure applications by employing an optimizer. The optimization is performed with the focus on reducing the profile loss for steam conditions. The experimental data verifies that the losses of the optimized profiles are reduced significantly compared to the datum blade profile measured in the same air rig. Secondly, the air-measured optimized blade profiles are used to design a 3D-optimized blade. In a numerical investigation, this optimized blade is analyzed in the steam turbine by applying steam conditions. The outlet Reynolds number of the 2nd stage is 8 × 105. This configuration is compared with the numerical results of the datum blade profile simulations. The relative isentropic total-to-total efficiency is increased by 0.6% due to the use of the optimized rotor blades. The benefit persists also for a maximum outlet Reynolds number of 9 × 106.
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Luymes, B. T., Q. An, A. M. Steinberg, X. F. Zhang, and T. Vandeputte. "Influence of Blade Loading Profile on Wake Dynamics in High-Pressure Turbine Cascades." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-77285.
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The influences of blade loading profile on wake convection and wake/wake interaction were studied in two different blade designs for high-pressure turbines (front-loaded and aft-loaded), installed in linear cascades. A high-speed moving bar apparatus replicated wake shedding, and a closed loop wind tunnel produced engine-relevant Mach numbers (Ma = 0.7) and Reynolds numbers (Re = 3 × 105). The front-loaded blades had approximately 10% greater total pressure loss when operated with unsteady wake passage. Phase conditioned PIV measurements were made in the aft portion of the blade channel and downstream of the blade trailing edge. The turbulence kinetic energy (TKE) in the wake was approximately 30% higher for the front-loaded blades when the wake entered the measurement field-of-view. The pressure field in the upstream region of the front-loaded blade design is believed to induce high magnitude strain rates — leading to increased TKE production — and more aggressively turn and dilate the unmixed wake — leading to increased mixing related losses. The higher TKE for the front-loaded blades largely dissipated by the time the wake reached the end of the blade passage. The interaction of the convected wake with the wake from the blade trailing edge caused periodic vortex shedding at the second harmonic of the convected wake frequency. This interaction also modulated the strength of the trailing edge wake. However, little difference was found in the modulation amplitudes between the different cases due to similar strengths of the convected wakes in this region. The higher wake TKE in the upstream portion of the blade channel for the front-loaded blades therefore is expected to be the cause of the increased total pressure loss.
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Mailach, Ronald, and Konrad Vogeler. "Aerodynamic Blade Row Interactions in an Axial Compressor: Part II — Unsteady Profile Pressure Distribution and Blade Forces." In ASME Turbo Expo 2003, collocated with the 2003 International Joint Power Generation Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/gt2003-38766.
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This two-part paper presents experimental investigations of unsteady aerodynamic blade row interactions in the first stage of the four-stage Low-Speed Research Compressor of Dresden. Both the unsteady boundary layer development and the unsteady pressure distribution of the stator blades are investigated for several operating points. The measurements were carried out on pressure side and suction side at midspan. In part II of the paper the investigations of the unsteady pressure distribution on the stator blades are presented. The experiments were carried out using piezoresistive miniature pressure sensors, which are embedded into the pressure and suction side surface of a single blade. The unsteady pressure distribution on the blade is analysed for the design point and an operating point near the stability limit. The investigations show that it is strongly influenced by both the incoming wakes and the potential flow field of the downstream rotor blade row. If a disturbance arrives the leading edge or the trailing edge of the blade the pressure changes nearly simultaneously along the blade chord. Thus the unsteady profile pressure distribution is independent of the wake propagation within the blade passage. A phase shift of the reaction on pressure and suction side is observed. The unsteady response of the boundary layer and the profile pressure distribution is compared. Based on the unsteady pressure distribution the unsteady pressure forces of the blades are calculated and discussed.
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Cheon, J. H., P. Milčák, A. Pacák, C. R. Kang, and M. Šťastný. "Profile Loss Prediction for High Pressure Steam Turbines." In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-56114.
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A method is presented for predicting the energy loss for a 2D turbine cascade blade operating in subsonic regions where the exit Mach number ≤ 0.8. A prediction method based on entropy creation was used to analyze the cascade profile loss mechanism. The basic profile loss model was introduced from the isentropic Mach number distribution along the blade surface and the trailing edge loss model was introduced from available test data, CFD results and available loss models. In addition, the Reynolds number correction curve was applied from previous research. Linear cascade test datasets which represent hub, mid-span and tip sections were used to validate this loss model.
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Kodama, Hidekazu, and Ken-ichi Funazaki. "Interpretation of Low-Pressure Turbine Profile Loss Generation Mechanisms From a Viewpoint of Blade Drag Forces." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-14519.
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Abstract This paper describes the interpretation of a generation mechanism of profile loss of low pressure turbine (LPT) blades from a viewpoint of blade drag forces. On the analogy of profile drag of an isolated body, the profile loss of a cascade blade is subdivided into two components, the loss due to friction drag and the loss due to pressure drag. The friction drag is equal to the integral of all axial component of shearing stresses taken over the surface of the blade. The pressure drag, which does not exist in an inviscid flow, is due to the fact that the presence of the boundary later modifies the pressure distribution on the blade. The losses due to friction drag and pressure drag are evaluated for two kinds of blade profiles using the results of steady incompressible Reynolds Averaged Navier-Stokes (RANS) simulations at three different Reynolds numbers (Re), 57,000, 100,000 and 147,000. It is found that the trend of the total profile loss with Reynolds number is mainly determined by the trend of the loss due to pressure drag with Reynolds number. A rise in the total profile loss of the blade with a laminar separation bubble on the suction surface at low Reynolds number is mainly attributed to the increase in the pressure drag due to thickened suction surface boundary layer by the enlarged separation bubble. The friction drag and the pressure drag are also estimated for the measured data of low speed linear cascade tests with a moving-bar mechanism. In the estimation, the pressure drag is derived from the estimated total profile loss and the estimated friction drag by using boundary layer integral equations. It is found that the trend of total profile loss with incoming wake passing frequency is almost determined by the trend of the loss due to pressure drag with the wake passing frequency.
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Gamal, Ahmed M., Bugra H. Ertas, and John M. Vance. "High-Pressure Pocket Damper Seals: Leakage Rates and Cavity Pressures." In ASME Turbo Expo 2006: Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-90858.
Full textAbstract:
The turbomachinery component of interest in this paper, the pocket damper seal, has the dual purpose of limiting leakage and providing an additional source of damping at the seal location. The rotordynamic coefficients of these seals (primarily the direct stiffness and damping) are highly dependent on the leakage rates through the seals and the pressures in the seals’ cavities. This paper presents both numerical predictions and experimentally obtained results for the leakage and the cavity pressures of pocket damper seals operating at high pressures. The seals were tested with air, at pressures up to 1000 Psi (6.92 MPa), as the working fluid. Earlier flow-prediction models were modified and used to obtain theoretical reference values for both mass flow-rates and pressures. Leakage and static pressure measurements on straight-through and diverging-clearance configurations of eight-bladed and twelve-bladed seals were used for code validation and for calculation of seal discharge coefficients. Higher than expected leakage rates were measured in the case of the twelve-bladed seal, while the leakage rates for the eight-bladed seals were predicted with reasonable accuracy. Differences in the axial pitch lengths of the cavities and the blade profiles of the seals are used to explain the discrepancy in the case of the twelve-bladed seal. The analysis code used also predicted the static cavity pressures reasonably well. Tests conducted on a six-bladed pocket damper seal to further investigate the effect of blade profile supported the results of the eight-bladed and twelve-bladed seal tests and matched theoretical predictions with satisfactory accuracy.
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Kodama, Hidekazu, and Ken-ichi Funazaki. "A Key Flow Parameter to the Profile Loss of Low-Pressure Turbine Blades." In ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/gt2021-58887.
Full textAbstract:
Abstract For an optimum performance design of low-pressure turbine (LPT) blades, it is crucial to understand the generation mechanism of profile loss properly. As the profile loss is usually taken to be the loss generated inside the blade boundary layer due to viscous effects, most of the efforts for the performance optimization have concentrated on the reduction in the boundary layer loss using the flow parameters that represent the loss generation in the boundary layers. Kodama and Funazaki [1] investigated the generation mechanism of profile loss from a view point of blade drag forces, friction drag force and pressure drag force, and suggested that the loss due to pressure drag is dominant in the profile loss of a typical LPT blade. The loss due to pressure drag is not a boundary layer loss that is generated in the boundary layers, but a mixing loss that is generated downstream of the trailing edge. It is necessary to clarify a key flow parameter to the loss due to pressure drag for an effective performance optimization. This paper aims at investigating the flow parameter that is a measure of the profile loss. In the investigation, the profile loss is broken down into the loss components which are expressed by the boundary layer integral parameters at the trailing edge. Then the loss components are categorized into the loss due to friction drag or the loss due to pressure drag. The loss level of each component is evaluated by using the results of steady Reynolds Averaged Navier-Stokes (RANS) simulations to assess the contribution to the total profile loss. The evaluations are conducted for two kinds of blade profiles at three different Reynolds numbers. It is found that the largest contributor to the loss due to pressure drag, consequently to the total profile loss, is the loss associated with a mixing of accelerated free stream flow by the flow blockage at the trailing edge plane. The loss level is simply determined by the flow blockage. This suggests that the flow blockage at the trailing edge plane is the most important flow parameter for an optimum performance design of LPT blades.
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Bigoni, Fabio, Roberto Maffulli, Tony Arts, and Tom Verstraete. "Metamodel-Assisted Optimization of a High-Lift Low Pressure Turbine Blade." In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63991.
Full textAbstract:
The scope of this work is to perform a single-objective optimization of the high-lift and aft-loaded T2 low pressure turbine blade profile previously designed at the von Karman Institute for Fluid Dynamics (VKI). At correct engine Mach and Reynolds numbers and for a uniform inflow at low turbulence level, a laminar separation bubble occurs in the decelerating part of the suction side. The main goal of the optimization is to obtain a high-lift and aft-loaded blade characterized by lower aerodynamic losses with respect to the original profile. The optimization uses a metamodel-assisted Differential Evolution algorithm, with an Ordinary Kriging metamodel performing the low-fidelity evaluations and Numeca FINE/Turbo for the high-fidelity ones. The numerical results relative to the optimized profile are compared with those obtained for the baseline profile, in order to highlight the improvements on the blade aerodynamic performance coming from the optimization process.
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Nanthini, R., B. V. S. S. S. Prasad, and Y. V. S. S. Sanyasiraju. "Sensitivity of Cascade Pressure Distribution for Inverse Design of Turbine Blade." In ASME 2019 Gas Turbine India Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gtindia2019-2631.
Full textAbstract:
Abstract In an iterative inverse design of a turbine blade, choice of initial guess profile is crucial. As the pressure distribution is very sensitive to the leading and trailing edge shapes and the profile slope and curvature, a good initial guess profile will help in faster convergence. In this paper, the sensitivity of the pressure distribution is determined by carrying out numerical simulations with ANSYS Fluent 17.2 for the inviscid flow. The flow domain comprises of a two dimensional transonic turbine cascade. It consists of a turbine blade enclosed by inlet, outlet and periodic boundaries. Inlet total pressure, total temperature and inlet angle are given as the boundary conditions at the inlet and static pressure is imposed at the outlet boundary. The flow is solved for continuity, momentum and energy equations. Sensitivity of different parameters — leading edge thickness, trailing edge thickness, leading edge shape, inlet and outlet wedge angle on the pressure distribution is demonstrated for VKI blade cascade. It is found that the pressure side of the profile is less sensitive and that even a small variation in suction side of the profile geometry can affect the performance of the blade significantly. It is shown that, with the proposed methodology and sequence of steps, the final guess blade is quite close to the original blade.