Endwall boundary layer separation in a single-stage axial-flow low-speed compressor and a high-stagger compressor cascade

1999 ◽  
Vol 65 (7) ◽  
pp. 217-224 ◽  
Author(s):  
H. Saathoff ◽  
U. Stark
Keyword(s):  
Boundary Layer ◽  
Axial Flow ◽  
Boundary Layer Separation ◽  
Single Stage ◽  
Compressor Cascade ◽  
Low Speed ◽  
Layer Separation

Tip Clearance Flow Induced Endwall Boundary Layer Separation in a Single–Stage Axial–Flow Low–Speed Compressor

2000 ◽  
Author(s):  
Horst Saathoff ◽  
Udo Stark
Keyword(s):  
Axial Flow ◽  
Boundary Layer Separation ◽  
Single Stage ◽  
Tip Clearance ◽  
Compressor Cascade ◽  
Tip Clearance Flow ◽  
Low Speed ◽  
Pressure Distributions ◽  
Oil Flow ◽  
Clearance Flow

The paper describes an investigation of the overtip end-wall flow in a single–stage axial–flow low–speed compressor utilizing an oil flow technique and a periodic multisampling pressure measurement technique. Representative oil flow pictures and ensemble averaged casingwall pressure distributions with standard deviations — supplemented by selected endwall oil flow pictures from a corresponding 2D compressor cascade — are shown and carefully analysed. The results enable the key features of the overtip endwall flow to be identified and changes with flow rate — or inlet angle — to be determined.

A New Design Concept of Highly-Loaded Axial Flow Compressor by Applying Boundary Layer Suction and 3D Blade Technique

2008 ◽  
Author(s):  
Xiaoqing Qiang ◽  
Songtao Wang ◽  
Weichun Lin ◽  
Zhongqi Wang
Keyword(s):  
Boundary Layer ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Boundary Layer Separation ◽  
Design Concept ◽  
Turning Angle ◽  
Boundary Layer Suction ◽  
Layer Separation ◽  
Flow Compressor ◽  
Highly Loaded

A new design concept of highly-loaded axial flow compressor by applying boundary layer suction and 3D blade technique was proposed in this paper. The basic idea of this design concept was that low reaction was adopted as while as increasing the rotor’s geometry turning angle, so that the boundary layer separation of a rotor could be eliminated and the rotor was kept working in high efficiency. This design concept would greatly increase the stator’s geometry turning angle, so boundary layer suction on stator cascades was adopted in order to restrain the boundary layer separation. In some situations, 3D blade technique was also applied in order to control the boundary layer separation more efficiently. The advantages of the above design concept were: the compressor’s pressure ratio was increased remarkably; boundary layer suction was only adopted in stator cascades so as to reduce the complexity of boundary layer suction structure. The key techniques of the new design concept were also explained in this paper. In order to increase the compressor’s pressure ratio, the geometry turning angle of rotor was increased greatly, and the rotor inlet was prewhirled to reduce the rotor’s reaction so as to restrain the rotor’s boundary separation. Boundary layer suction was carried out in the stator cascades (mainly on suction side), hub and shroud in order to control the flow separation. 3D blade technique could be adopted if necessary. The limitation of the application of this design concept was also pointed out through the analysis of the Mach number at rotor inlet, the prewhirl angle of rotor, the work distribution along span wise and the control method of stator separation. Numerical simulation was carried out on a single low-reaction compressor stage with IGV in order to demonstrate the new design concept. By using boundary layer suction and 3D blade technique, the energy loss in stator cascades was greatly reduced and the whole stage’s isentropic efficiency was about 90%. The low-reaction stage’s aerodynamic load was double than conventional design. The boundary layer separation could be effectively controlled by proper combination of boundary layer suction and bowed or twisted blade. The numerical result proved that the new design concept was feasible and had a wide application area.

Control of Separations in a Highly-Loaded Axial Compressor Cascade by Tailored Boundary Layer Suction

2015 ◽  
Author(s):  
Xiaochen Mao ◽  
Bo Liu ◽  
Guochen Zhang
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Separation ◽  
Flow Fields ◽  
Experimental Investigations ◽  
Compressor Cascade ◽  
Matching Problem ◽  
Boundary Layer Suction ◽  
Layer Separation ◽  
End Wall ◽  
Suction Flow

In order to study the effectiveness and mechanisms of boundary layer suction (BLS) in controlling both the boundary layer separation on the whole span of suction surface (SS) and the three-dimensional (3D) separation in the corner, a 3D linear compressor cascade was investigated by tailored BLS. First, experimental investigations at a range of incidences from −10° to 10° were undertaken on both the original cascade and the aspirated cascade (SS1) in a high-subsonic cascade wind tunnel. The results show that the profile loss coefficient of the aspirated cascade is reduced remarkably as the suction flow ratio increases at the incidences from −5° to 8°. Based on the experimental investigations, numerical simulations were employed to study the flow fields of the original and aspirated cascade in detail. It was found that part blade span suction on the aspirated cascade can effectively remove the separation at the suction span where suction slot exists, resulting that the flow fields of other spans deteriorated. Due to the interaction of separations both on the SS and the end-wall, the 3D separation in the corner are more complicated, so another three tailored BLS schemes were designed totally in order to fully remove both the boundary-layer separation on SS and the 3D separation. It was found that the span-wise distribution of static pressure was changed after suction and it could influence the transport of the low-energy fluid between the end-wall and the mid-span. The separation over the whole span of SS and the 3D separation in the corner were fully eliminated by combined suction scheme (CS). Finally, the incidence characteristics of the 3D linear cascade under the control of CS scheme were investigated numerically together with the suction flow rate matching problem of the different suction slots.

The boundary layer separation from streamlined surfaces and new ways of its prevention in diffusers

2017 ◽  
Author(s):  
Arkady Zaryankin ◽  
Andrey Rogalev ◽  
Ivan Komarov ◽  
V. Kindra ◽  
S. Osipov
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Separation ◽  
Layer Separation

scholarly journals Leading Edge Blowing to Mimic and Enhance the Serration Effects for Aerofoil

2021 ◽  
Vol 11 (6) ◽  
pp. 2593
Author(s):  
Yasir Al-Okbi ◽  
Tze Pei Chong ◽  
Oksana Stalnov
Keyword(s):  
Boundary Layer ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Boundary Layer Separation ◽  
Shear Instability ◽  
Vortical Flow ◽  
High Angle ◽  
High Angle Of Attack ◽  
Layer Separation ◽  
Aerodynamic Performances

Leading edge serration is now a well-established and effective passive control device for the reduction of turbulence–leading edge interaction noise, and for the suppression of boundary layer separation at high angle of attack. It is envisaged that leading edge blowing could produce the same mechanisms as those produced by a serrated leading edge to enhance the aeroacoustics and aerodynamic performances of aerofoil. Aeroacoustically, injection of mass airflow from the leading edge (against the incoming turbulent flow) can be an effective mechanism to decrease the turbulence intensity, and/or alter the stagnation point. According to classical theory on the aerofoil leading edge noise, there is a potential for the leading edge blowing to reduce the level of turbulence–leading edge interaction noise radiation. Aerodynamically, after the mixing between the injected air and the incoming flow, a shear instability is likely to be triggered owing to the different flow directions. The resulting vortical flow will then propagate along the main flow direction across the aerofoil surface. These vortical flows generated indirectly owing to the leading edge blowing could also be effective to mitigate boundary layer separation at high angle of attack. The objectives of this paper are to validate these hypotheses, and combine the serration and blowing together on the leading edge to harvest further improvement on the aeroacoustics and aerodynamic performances. Results presented in this paper strongly indicate that leading edge blowing, which is an active flow control method, can indeed mimic and even enhance the bio-inspired leading edge serration effectively.

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