A Numerical Investigation of the Effect of End-Wall Boundary Layer Skew on the Aerodynamic Performance of a Low Aspect Ratio, High Turning Compressor Cascade

2009 ◽  
pp. 107-114 ◽  
Author(s):  
Martin Böhle ◽  
Udo Stark
Keyword(s):  
Boundary Layer ◽  
Aspect Ratio ◽  
Numerical Investigation ◽  
Aerodynamic Performance ◽  
Compressor Cascade ◽  
Low Aspect Ratio ◽  
Wall Boundary Layer ◽  
Wall Boundary ◽  
End Wall

A Numerical Investigation of the Effect of End-Wall Boundary Layer Skew on the Aerodynamic Performance of a Low Aspect Ratio, High Turning Compressor Cascade

2007 ◽  
Author(s):  
M. Boehle ◽  
U. Stark
Keyword(s):  
Boundary Layer ◽  
Aspect Ratio ◽  
Numerical Investigation ◽  
Boundary Layers ◽  
Aerodynamic Performance ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Wall Boundary Layer ◽  
Wall Boundary ◽  
End Wall

The paper reports on a numerical investigation into the effects of inlet boundary layer skew on the aerodynamic performance of a high turning 50 deg, 2D compressor cascade. The cascade geometry is representative of stator hub sections in highly loaded single-stage axial-flow low-speed compressors. 2D blades with NACA 65 thickness distribution on circular arc camber lines were used. The blade aspect ratio was 1.0, the space/chord ratio 0.5 and the stagger angle 25 deg. The simulations were done with a commercially available, steady three-dimensional RANS solver with the Spalart-Allmaras turbulence model. The incoming end-wall boundary layers were assumed to be collateral or skewed. In both cases the profile boundary layers were fully turbulent. The Reynolds-number was fixed at 600000 and the thickness of the incoming end-wall boundary layer was 0.1. Results are shown for an inlet-air angle of 50 deg, representing the impact free inlet-air angle of a hypothetical cascade with zero-thickness blades. Contrary to what has been expected, the results do not show (hub) corner stall, neither with nor without end-wall boundary layer skew. Flow reversal happens to occur almost exclusively on the suction surface of the blades, not on the end-walls. The end-wall flow is highly overturned, when the incoming boundary layer is collateral and is much less curved when the incoming boundary layer is skewed and (re)energized. This in turn leads to an interaction between the end-wall and blade suction surface flow which is much stronger in the first than in the second case with corresponding higher and lower losses, respectively.

Aerodynamic Characteristics of a Rectangular Wing With a Tip Clearance in a Channel

1977 ◽  
Vol 44 (4) ◽  
pp. 541-547
Author(s):  
Y. Sugiyama
Keyword(s):  
Boundary Layer ◽  
Aspect Ratio ◽  
Drag Coefficient ◽  
Aerodynamic Characteristics ◽  
Tip Clearance ◽  
Wall Boundary Layer ◽  
Wall Boundary ◽  
Lift And Drag ◽  
Lift And Drag Coefficient ◽  
End Wall

Aerodynamic characteristics of a single, stationary wing, whose tip is in an end-wall boundary layer, are studied experimentally to determine the effects of aspect ratio, tip clearance, angle of attack and end-wall boundary layer. Spanwise distributions of the lift and drag coefficient are derived and interpreted from the data obtained by chordwise pressure measurements on the wing surface. The results indicate that the slope of the lift curve, the angle of zero lift and the drag coefficient reach a maximum at an optimum value of the tip clearance in a certain range of the aspect ratio. Interesting information is also obtained for effects of the end-wall boundary layer on the lift and drag of the wing with a slot.

Effects of a Skewed Inlet Boundary Layer on the Aerodynamic Performance of a Stator-Hub Equivalent High-Turning Compressor Cascade

2016 ◽  
Author(s):  
Christoph Bode ◽  
Jörg Hoffmann ◽  
Udo Stark
Keyword(s):  
Boundary Layer ◽  
Aspect Ratio ◽  
Axial Flow ◽  
Aerodynamic Performance ◽  
Compressor Cascade ◽  
Numerical Investigations ◽  
Performance Improvements ◽  
Low Aspect Ratio ◽  
Cascade Flow ◽  
Inlet Angle

The paper reports on numerical investigations into the effects of inlet boundary layer skew on the aerodynamic performance of a low aspect ratio, high turning compressor cascade. The cascade geometry corresponds to the hub section geometry of a low aspect ratio stator of a highly loaded single-stage axial-flow low-speed compressor (fan). The skewed cascade flow simulates the reenergized stator hub flow and brings about a much better performance with inlet skew than without. However, the performance improvements caused by a skewed inlet boundary layer decrease with increasing inlet angle.

Effect of Boundary Layer Suction on Aerodynamic Performance of High-Turning Compressor Cascade

2013 ◽  
Author(s):  
Longxin Zhang ◽  
Shaowen Chen ◽  
Hao Xu ◽  
Jun Ding ◽  
Songtao Wang
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Experimental Studies ◽  
Aerodynamic Performance ◽  
Parameter Distribution ◽  
Compressor Cascade ◽  
Boundary Layer Suction ◽  
End Wall ◽  
Low Speed Wind Tunnel ◽  
Good Agreement

Compared with suction slots, suction holes are (1) flexible in distribution; (2) alterable in size; (3) easy to fabricate and (4) high in strength. In this paper, the numerical and experimental studies for a high turning compressor cascade with suction air removed by using suction holes in the end-wall at a low Mach numbers are carried out. The main objective of the investigation is to study the influence of different suction distributions on the aerodynamic performance of the compressor cascade and to find a better compound suction scheme. A numerical model was first made and validated by comparing with the experimental results. The computed flow visualization and exit parameter distribution showed a good agreement with experimental data. Second, the model was then used to simulate the influence of different suction distributions on the aerodynamic performance of the compressor cascade. A better compound suction scheme was obtained by summarizing numerical results and tested in a low speed wind tunnel. As a result, the compound suction scheme can be used to significantly improve the performance of the compressor cascade because the corner separation gets further suppressed.

An Axial Compressor End-Wall Boundary Layer Calculation Method

1979 ◽  
Vol 101 (2) ◽  
pp. 233-245 ◽  
Author(s):  
J. De Ruyck ◽  
C. Hirsch ◽  
P. Kool
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Velocity Profile ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Tip Clearance ◽  
Wall Region ◽  
Wall Boundary Layer ◽  
Wall Boundary ◽  
End Wall

An axial compressor end-wall boundary layer theory which requires the introduction of three-dimensional velocity profile models is described. The method is based on pitch-averaged boundary layer equations and contains blade force-defect terms for which a new expression in function of transverse momentum thickness is introduced. In presence of tip clearance a component of the defect force proportional to the clearance over blade height ratio is also introduced. In this way two constants enter the model. It is also shown that all three-dimensional velocity profile models present inherent limitations with regard to the range of boundary layer momentum thicknesses they are able to represent. Therefore a new heuristic velocity profile model is introduced, giving higher flexibility. The end-wall boundary layer calculation allows a correction of the efficiency due to end-wall losses as well as calculation of blockage. The two constants entering the model are calibrated and compared with experimental data allowing a good prediction of overall efficiency including clearance effects and aspect ratio. Besides, the method allows a prediction of radial distribution of velocities and flow angles including the end-wall region and examples are shown compared to experimental data.

scholarly journals LES and RANS Analysis of the End-Wall Flow in a Linear LPT Cascade: Part I — Flow and Secondary Vorticity Fields Under Varying Inlet Condition

2018 ◽  
Author(s):  
R. Pichler ◽  
Yaomin Zhao ◽  
R. D. Sandberg ◽  
V. Michelassi ◽  
R. Pacciani ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Secondary Flow ◽  
Flow Characteristics ◽  
Flow Region ◽  
Secondary Flows ◽  
Wall Boundary Layer ◽  
Wall Boundary ◽  
Wall Flow ◽  
End Wall ◽  
The Impact

In low-pressure-turbines (LPT) around 60–70% of losses are generated away from end-walls, while the remaining 30–40% is controlled by the interaction of the blade profile with the end-wall boundary layer. Experimental and numerical studies have shown how the strength and penetration of the secondary flow depends on the characteristics of the incoming end-wall boundary layer. Experimental techniques did shed light on the mechanism that controls the growth of the secondary vortices, and scale-resolving CFD allowed to dive deep into the details of the vorticity generation. Along these lines, this paper discusses the end-wall flow characteristics of the T106 LPT profile at Re = 120K and M = 0.59 by benchmarking with experiments and investigating the impact of the incoming boundary layer state. The simulations are carried out with proven Reynolds-averaged Navier–Stokes (RANS) and large-eddy simulation (LES) solvers to determine if Reynolds Averaged models can capture the relevant flow details with enough accuracy to drive the design of this flow region. Part I of the paper focuses on the critical grid needs to ensure accurate LES, and on the analysis of the overall time averaged flow field and comparison between RANS, LES and measurements when available. In particular, the growth of secondary flow features, the trace and strength of the secondary vortex system, its impact on the blade load variation along the span and end-wall flow visualizations are analysed. The ability of LES and RANS to accurately predict the secondary flows is discussed together with the implications this has on design.

A Method for Calculating Axial Turbomachine End Wall Turbulent Boundary Layers

1989 ◽  
Author(s):  
Kang Shun ◽  
Liu Fengjun ◽  
Wang Zhongqi
Keyword(s):  
Boundary Layer ◽  
Iterative Solution ◽  
Stream Surface ◽  
Wall Boundary Layer ◽  
Wall Boundary ◽  
Curvilinear Coordinate ◽  
Orthogonal Curvilinear Coordinate System ◽  
Layer Flow ◽  
End Wall ◽  
Differential And Integral Equations

Based on two families of relative stream-surface theory, the differential and integral equations of the endwall boundary layer in the S2 stream surface (hub to tip stream surface) have been established in the orthogonal curvilinear coordinate system in the present paper. By directly associating the blade force defects with the warping of S2 stream surface near the endwall, we have proposed a new method for predicting the endwall boundary layer. This method can be used to conduct the interactions of the end wall boundary layer with the S2 stream surface potentisl flow, in order to get the iterative solution of the end wall boundary layer flow with the potential flow in S2 stream surface. The predicted results have shown that the present method is acceptable.

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