Unsteady flows of a highly loaded turbine blade with flat endwall and contoured endwall

2021 ◽  
pp. 106989
Author(s):  
Xinrong Su ◽  
Xiutao Bian ◽  
Hui Li ◽  
Xin Yuan
Keyword(s):  
Turbine Blade ◽  
Unsteady Flows ◽  
Highly Loaded

Surface pressure characteristics of a highly loaded turbine blade at design and off-design conditions; a CFD methodology

2017 ◽  
Vol 24 (3) ◽  
pp. 469-482
Author(s):  
S. Vakilipour ◽  
M. Habibnia ◽  
M. H. Sabour ◽  
R. Riazi ◽  
M. Mohammadi
Keyword(s):  
Turbine Blade ◽  
Surface Pressure ◽  
Highly Loaded ◽  
Pressure Characteristics

Unsteady Wake-Induced Boundary Layer Transition in High Lift LP Turbines

1998 ◽  
Vol 120 (1) ◽  
pp. 28-35 ◽  
Author(s):  
V. Schulte ◽  
H. P. Hodson
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Turbine Blade ◽  
Reynolds Numbers ◽  
Boundary Layer Development ◽  
Unsteady Wake ◽  
Lp Turbine ◽  
Wake Passing ◽  
Layer Development ◽  
Highly Loaded

The development of the unsteady suction side boundary layer of a highly loaded LP turbine blade has been investigated in a rectilinear cascade experiment. Upstream rotor wakes were simulated with a moving-bar wake generator. A variety of cases with different wake-passing frequencies, different wake strength, and different Reynolds numbers were tested. Boundary layer surveys have been obtained with a single hotwire probe. Wall shear stress has been investigated with surface-mounted hot-film gages. Losses have been measured. The suction surface boundary layer development of a modern highly loaded LP turbine blade is shown to be dominated by effects associated with unsteady wake-passing. Whereas without wakes the boundary layer features a large separation bubble at a typical cruise Reynolds number, the bubble was largely suppressed if subjected to unsteady wake-passing at a typical frequency and wake strength. Transitional patches and becalmed regions, induced by the wake, dominated the boundary layer development. The becalmed regions inhibited transition and separation and are shown to reduce the loss of the wake-affected boundary layer. An optimum wake-passing frequency exists at cruise Reynolds numbers. For a selected wake-passing frequency and wake strength, the profile loss is almost independent of Reynolds number. This demonstrates a potential to design highly loaded LP turbine profiles without suffering large losses at low Reynolds numbers.

A Low Reynolds Number Experimental Evaluation of Tubercles on a Low-Pressure Turbine Cascade

2019 ◽  
Author(s):  
Stephen A. Pym ◽  
Asad Asghar ◽  
William D. E. Allan ◽  
John P. Clark
Keyword(s):  
Boundary Layer ◽  
Turbine Blade ◽  
Reynolds Numbers ◽  
Low Pressure ◽  
Blade Profile ◽  
Suction Surface ◽  
Low Reynolds Numbers ◽  
Low Pressure Turbine ◽  
Low Reynolds ◽  
Highly Loaded

Abstract Aircraft are operating at increasingly high-altitudes, where decreased air density and engine power settings have led to increasingly low Reynolds numbers in the low-pressure turbine portion of modern-day aeroengines. These operating conditions, in parallel with highly-loaded blade profiles, result in non-reattaching laminar boundary layer separation along the blade suction surface, increasing loss and decreasing engine performance. This work presents an experimental investigation into the potential for integrated leading-edge tubercles to improve blade performance in this operating regime. A turn-table cascade test-section was constructed and commissioned to test a purpose-designed, forward-loaded, low-pressure turbine blade profile at various incidences and Reynolds numbers. Baseline and tubercled blades were tested at axial chord Reynolds numbers at and between 15 000 and 60 000, and angles of incidence ranging from −5° to +10°. Experimental data collection included blade surface pressure measurements, total pressure loss in the blade wakes, hot-wire anemometry, surface hot-film measurements, and surface flow visualization using tufts. Test results showed that the implementation of tubercles did not lead to a performance enhancement. However, useful conclusions were drawn regarding the ability of tubercles to generate stream-wise vortices at ultra-low Reynolds numbers. Additional observations helped to characterize the suction surface boundary layer over the highly-loaded, low-pressure turbine blade profile when at off-design conditions. Recommendations were made for future work.

scholarly journals Experimental and CFD analyses of a highly-loaded gas turbine blade

2017 ◽  
Vol 126 ◽  
pp. 770-777 ◽  
Author(s):  
Tommaso Bacci ◽  
Andrea Gamannossi ◽  
Lorenzo Mazzei ◽  
Alessio Picchi ◽  
Lorenzo Winchler ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Gas Turbine Blade ◽  
Cfd Analyses ◽  
Highly Loaded

An experimental study of separation control on ultra-highly-loaded low pressure turbine blade by surface roughness

2015 ◽  
Vol 24 (3) ◽  
pp. 229-238 ◽  
Author(s):  
Shuang Sun ◽  
Zhijun Lei ◽  
Xingen Lu ◽  
Shengfeng Zhao ◽  
Junqiang Zhu
Keyword(s):  
Experimental Study ◽  
Surface Roughness ◽  
Turbine Blade ◽  
Low Pressure ◽  
Separation Control ◽  
Low Pressure Turbine ◽  
Highly Loaded

Numerical Study of Transitional Rough Wall Boundary Layer

2012 ◽  
Author(s):  
Witold Elsner ◽  
Piotr Warzecha
Keyword(s):  
Boundary Layer ◽  
Surface Roughness ◽  
Flat Plate ◽  
Turbine Blade ◽  
Numerical Study ◽  
Suction Side ◽  
Rough Wall ◽  
Correct Prediction ◽  
Modeling Approach ◽  
Highly Loaded

The paper presents the verification of boundary layer modeling approach, which relies on a γ-Reθt model proposed by Menter et al. [1]. This model was extended by laminar-turbulent transition correlations proposed by Piotrowski et al. [2] as well as Stripf et al. [3] correlations, which take into account the effects of surface roughness. To blend between the laminar and fully turbulent boundary layer over rough wall the modified intermittency equation is used. To verify the model a flat plate with zero and non-zero pressure gradients test cases as well as the high pressure turbine blade case were chosen. Further on, the model was applied for unsteady calculations of turbine blade profile as well as the Lou and Hourmouziadis [4] flat plate test case, with induced pressure profile typical for suction side of highly-loaded turbine airfoil. The combined effect of roughness and wake passing were studied. The studies proved that the proposed modeling approach (ITMR hereinafter) appeared to be sufficiently precise and enabled for a qualitatively correct prediction of the boundary layer development for the tested simple flow configurations. The results of unsteady calculations indicated that the combined impact of wakes and the surface roughness could be beneficial for the efficiency of the blade rows, but mainly in the case of strong separation occurring on highly-loaded blade profiles. It was also demonstrated that the roughness hardly influences the location of wake induced transition, but has an impact on the flow in between the wakes.

scholarly journals Unsteady Wake-Induced Boundary Layer Transition in High Lift LP Turbines

1996 ◽  
Author(s):  
Volker Schulte ◽  
Howard P. Hodson
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Turbine Blade ◽  
Reynolds Numbers ◽  
Boundary Layer Development ◽  
Unsteady Wake ◽  
Lp Turbine ◽  
Wake Passing ◽  
Layer Development ◽  
Highly Loaded

The development of the unsteady suction side boundary layer of a highly loaded LP turbine blade has been investigated in a rectilinear cascade experiment. Upstream rotor wakes were simulated with a moving-bar wake generator. A variety of cases with different wake-passing frequencies, different wake strength and different Reynolds-numbers were tested. Boundary layer surveys have been obtained with a single hot-wire probe. Wall shear stress has been investigated with surface-mounted hot-film gauges. Losses have been measured. The suction surface boundary layer development of a modern highly loaded LP turbine blade is shown to be dominated by effects associated with unsteady wake-passing. Whereas without wakes the boundary layer features a large separation bubble at a typical cruise Reynolds-number, the bubble was largely suppressed if subjected to unsteady wake-passing at a typical frequency and wake strength. Transitional patches and becalmed regions, induced by the wake, dominated the boundary layer development. The becalmed regions inhibited transition and separation and are shown to reduce the loss of the wake-affected boundary layer. An optimum wake-passing frequency exists at cruise Reynolds-numbers. For a selected wake-passing frequency and wake-strength, the profile loss is almost independent of Reynolds-number. This demonstrates a potential to design highly loaded LP turbine profiles without suffering large losses at low Reynolds-numbers.

Uncertainty Quantification of Heat Transfer for a Highly Loaded Gas Turbine Blade Endwall Using Polynomial Chaos

2016 ◽  
Author(s):  
Peiyuan Zhu ◽  
Yong Yan ◽  
Liming Song ◽  
Jun Li ◽  
Zhenping Feng
Keyword(s):  
Heat Transfer ◽  
Uncertainty Quantification ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Heat Transfer Performance ◽  
Polynomial Chaos ◽  
Transfer Performance ◽  
Uncertainty Factors ◽  
Operation Conditions ◽  
Highly Loaded

The durability of highly loaded gas turbine blade is significantly impacted by high heat transfer. The heat transfer performance of the gas turbine endwall can be varied significantly due to the impacts of uncertainties in the manufacturing process and operation conditions. In this work, an uncertainty quantification (UQ) method is proposed by integrating generalized polynomial chaos expansions, non-intrusive spectral projection and Smolyak sparse grids. Then coupled with three dimensional (3D) Reynolds-Averaged Navier-Stokes (RANS) solutions, an uncertainty quantification procedure is carried out for heat transfer performance of highly loaded blade endwall. Wherein, the effects of the variation of geometric parameters and operation conditions are taken into account. Specifically, the endwall heat transfer performance of a typical highly loaded turbine blade named Pack-B is numerically investigated. The turbulence intensity Tuinlet and Reynolds number Reinlet of inlet flow are considered as flow condition uncertainty parameters. As geometrical uncertainty parameters, the radius r and minimum angle α of blade root fillet are considered. These uncertainty factors have important influence on the secondary flow structure, resulting in significant variation of heat transfer performance of the endwall. Non-intrusive Polynomial Chaos (NIPC) is used to build a surrogate to reduce the quantity of the time consuming CFD simulation. A total of 137 sparse-grid-based design-of-experiment computations were carried out to build the high-fidelity surrogate. Using above method, the probability density function of the Nusselt number ( Nu ) of the endwall is obtained. The overall variation of Nu can be more than 10% due to the effect of the uncertainty factors. Finally, the sensitivity analysis shows that Reinlet has the most important influence on heat transfer performance of the whole endwall and other uncertainty factors also have significant effect on heat transfer performance at some local regions of the endwall such as wake region and middle part of blade passage.

A Comparative Numerical Study of Aerodynamics and Heat Transfer on Transitional Flow Around a Highly Loaded Turbine Blade With Flow Separation Using RANS, URANS and LES

2014 ◽  
Author(s):  
Meinhard T. Schobeiri ◽  
Ali Nikparto
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbine Blade ◽  
Numerical Study ◽  
Transitional Flow ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Eddy Simulation ◽  
Reynolds Averaged Navier Stokes ◽  
Highly Loaded

The paper numerically and experimentally investigates the behavior of the boundary layer development and heat transfer along the suction and pressure surfaces of a highly loaded turbine blade with separation. To evaluate and compare the predictive capability of different numerical methods, Reynolds Averaged Navier-Stokes based solvers (RANS), Unsteady Reynolds Averaged Navier Stokes equation (URANS) as well as Large Eddy Simulation (LES) are used. The results of each individual numerical method are compared with the measurements. For this purpose, extensive boundary layer and heat transfer measurements were performed in the unsteady boundary layer cascade facility of the Turbomachinery Performance and Flow Research Laboratory (TPFL) of Texas A&M University. Aerodynamics experiments include measuring the onset of the boundary, its transition, separation and re-attachment using miniature hot wire probes. Heat transfer measurements along the suction and pressure surfaces were conducted utilizing a specially designed heat transfer blade that was instrumented with liquid crystal coating. Comparisons of the experimental and numerical results detail differences in predictive capabilities of the RANS based solvers and LES.

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