A Fundamental Criterion for the Application of Rotor Casing Treatment

1979 ◽  
Vol 101 (2) ◽  
pp. 237-243 ◽  
Author(s):  
E. M. Greitzer ◽  
J. P. Nikkanen ◽  
D. E. Haddad ◽  
R. S. Mazzawy ◽  
H. D. Joslyn
Keyword(s):  
Experimental Investigation ◽  
Flow Field ◽  
Total Pressure ◽  
The Other ◽  
Substantial Decrease ◽  
Stall Margin ◽  
Casing Treatment ◽  
Compressor Rotor

An experimental investigation has been carried out on the influence of grooved casing treatment on the stall margin of a compressor rotor. Tests were conducted with two rotor builds having different solidities (but all other parameters identical) so that one of the rotors exhibited a wall, or casing, type of stall, while the other showed a blade stall. It was found that the casing treatment, when compared to the solid casing, was very effective in increasing the stall margin of the wall stall configuration, whereas there was little or no change in the stall point of the blade stall configuration. Detailed relative frame measurements of the rotor exit flow field were also taken as part of the program. These showed that in a wall stall situation, the use of casing treatment produced a substantial decrease in the relative total pressure defect, compared with the solid casing, while this was not true for the blade stall type of blading. The results of the experiments, both in overall measurements and in the detailed relative frame traverses, support the hypothesis that casing treatment is effective only in a situation in which a wall stall exists.

Numerical Investigation of Effect of Inlet Distortion on Compressor Flow Field and Stability

2017 ◽  
Author(s):  
HaoGuang Zhang ◽  
Kang An ◽  
Feng Tan ◽  
YanHui Wu ◽  
WuLi Chu
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Total Pressure ◽  
Tip Clearance ◽  
Numerical Work ◽  
Stall Margin ◽  
Numerical Investigations ◽  
Inlet Distortion ◽  
Compressor Rotor ◽  
The Stability

The compressor aerodynamic design is conducted under the condition of clean inlet in general, but a compressor often operates under the condition of inlet distortion in the practical application. It has been proven by a lot of experimental and numerical investigations that inlet distortion can decrease the performance and stability of compressors. The circumferential or radial distorted inlet in mostly numerical investigations is made by changing the total pressure and total temperature in the inlet ring surface of the compressors. In most of inlet distortion experiments, distorted inlets are usually created by using wire net, flashboards, barriers or the generator of rotating distortion. The fashion of generating distorted inlet for experiment is different from that for numerical simulation. Consequently, the flow mechanism of affecting the flow field and stability of a compressor with distorted inlet for experiment is partly different than that for numerical simulation. In the numerical work reported here, the inlet distortion is generated by setting some barriers in the inlet ring surface of an axial subsonic compressor rotor. Two kinds of distorted inlet are investigated to exploring the effect of distorted range on the flow field and stability of the compressor with ten-passage unsteady numerical method. The numerical results show that the inlet distortions not only degrade the total pressure and efficiency of the compressor rotor, but also decrease the stability of the rotor. The larger the range of distorted inlet is, the stronger the adverse effect is. The comprehensive stall margin for the inlet distortion of 24 degrees and 48 degrees of ten-passages is reduced about 3.35% and 5.88% respectively. The detailed analysis of the flow field in the compressor indicates that the blockage resulted from tip clearance leakage vortex (TLV) and the flow separation near the suction surfaces of some blades tip for distorted inlet is more serious than that resulted from TLV for clean inlet. Moreover, the larger the range of distorted inlet is, the larger the range of the blockage is. The analysis of unsteady flow shows that during this process, which is that one rotor blade passes through the region affected by the distorted inlet, the range of the blockage in the rotor passage increases first, then reduces, and increases last.

Experimental Investigation of Non-Axisymmetrical Flow Control in a Low Speed Axial Compressor

2009 ◽  
Author(s):  
Huabing Jiang ◽  
Yajun Lu ◽  
Wei Yuan ◽  
Qiushi Li
Keyword(s):  
Flow Field ◽  
Flow Control ◽  
Total Pressure ◽  
Pressure Rise ◽  
Separated Flow ◽  
Experimental Results ◽  
Stall Margin ◽  
Casing Treatment ◽  
Compressor Performance ◽  
Compressor Efficiency

The non-axisymmetric feature of the compressor separated flow field should be considered when flow control technology is utilized to improve compressor performance. An experiment is performed to investigate the effectiveness of non-axisymmetric flow control using arc curve skewed slot casing treatment in the paper. A simplified non-axisymmetric excitation model is presented with variable circumferential excitation extent and location. FFT analysis results indicate that the frequency spectrum of the non-axisymmetric excitation is similar with that of the whole circumferential excitation. The non-axisymmetric excitation possesses the same dominate frequency, smaller amplitude and wider frequency bandwidth compared to the whole circumferential excitation. A simplified circumferential non-axisymmetric arc curve skewed slot casing treatment is utilized to perform non-axisymmetric excitation on the separated flow field of a low speed single stage axial compressor under both uniform and distorted inlet conditions. Experimental results indicate that the non-axisymmetric slotted casing treatment presents strong flow control capability, which could improve compressor efficiency, total pressure rise coefficient and stall margin. For the distorted inlet condition, the stall margin, total pressure rise and efficiency of the compressor are respectively improved by 47.4%, 12.7% and 0.7% compared to the solid casing, and the compressor efficiency is improved by 1.4% compared to the whole circumferential excitation. For uniform inlet condition, the non-axisymmetric excitation can improve compressor efficiency by 1.0% and 1.5% respectively compared to the solid casing and the whole circumferential excitation. The whole circumferential excitation can also improve the compressor total pressure rise coefficient and stall margin, on the contrary, it decreases compressor efficiency. As a result, the non-axisymmetric slotted casing treatment can achieve more excellent compressor performance than the whole circumferential excitation does. Experimental results also indicate that the circumferential extent and location of the non-axisymmetric excitation can influence the effectiveness of the non-axisymmetric excitation. The best compressor performance can be achieved only when the non-axisymmetric excitation is tuned to match the asymmetric compressor separated flow field. Analysis on the experimental results indicates that compressor efficiency improvement achieved with the non-axisymmetric excitation can not simply attribute to the flow loss reduction induced by fewer casing slots. The flow loss reduction within undistorted sector, the circumferential flow exchange and the dynamic response induced by the non-axisymmetric excitation, the unsteady coupling between the non-axisymmetric excitation and the separated flow field might be the key flow factors to influence the compressor flow field structure, and hence influence the compressor performance.

Effects of Inlet Distortion on the Flow Field in a Transonic Compressor Rotor

1996 ◽  
Author(s):  
Chunill Hah ◽  
Douglas C. Rabe ◽  
Thomas J. Sullivan ◽  
Aspi R. Wadia
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Viscous Flow ◽  
Total Pressure ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Aerodynamic Loss ◽  
Transonic Compressor ◽  
Inlet Distortion ◽  
Compressor Rotor

The effects of circumferential distortions in inlet total pressure on the flow field in a low-aspect-ratio, high-speed, high-pressure-ratio, transonic compressor rotor are investigated in this paper. The flow field was studied experimentally and numerically with and without inlet total pressure distortion. Total pressure distortion was created by screens mounted upstream from the rotor inlet. Circumferential distortions of 8 periods per revolution were investigated at two different rotor speeds. The unsteady blade surface pressures were measured with miniature pressure transducers mounted in the blade. The flow fields with and without inlet total pressure distortion were analyzed numerically by solving steady and unsteady forms of the Reynolds-averaged Navier-Stokes equations. Steady three-dimensional viscous flow calculations were performed for the flow without inlet distortion while unsteady three-dimensional viscous flow calculations were used for the flow with inlet distortion. For the time-accurate calculation, circumferential and radial variations of the inlet total pressure were used as a time-dependent inflow boundary condition. A second-order implicit scheme was used for the time integration. The experimental measurements and the numerical analysis are highly complementary for this study because of the extreme complexity of the flow field. The current investigation shows that inlet flow distortions travel through the rotor blade passage and are convected into the following stator. At a high rotor speed where the flow is transonic, the passage shock was found to oscillate by as much as 20% of the blade chord, and very strong interactions between the unsteady passage shock and the blade boundary layer were observed. This interaction increases the effective blockage of the passage, resulting in an increased aerodynamic loss and a reduced stall margin. The strong interaction between the passage shock and the blade boundary layer increases the peak aerodynamic loss by about one percent.

scholarly journals Recess Vane Passive Stall Control

1992 ◽  
Author(s):  
M. Ziabasharhagh ◽  
A. B. McKenzie ◽  
R. L. Elder
Keyword(s):  
Experimental Investigation ◽  
Axial Flow ◽  
Operating Efficiency ◽  
Stall Margin ◽  
Casing Treatment ◽  
Inlet Distortion ◽  
Stall Margin Improvement ◽  
Stage Characteristic ◽  
Stall Control

An experimental investigation has been carried out on the influence of a vaned recessed casing treatment on the stall margin improvement of axial flow fans with different hub to tip ratio, with and without inlet distortion. The inlet distortion tests were conducted on a 0.5 hub to tip ratio fan and significant increases in the flow range with only small drops in operating efficiency were observed. The clean flow tests were conducted on higher hub to tip ratio fans (0.7 and 0.9). In each case the stage characteristic was compared with the results obtained with a solid casing. Significant increases in the flow range, with only modest or no loss in operating efficiency, were observed for optimum configurations at both diameter ratios.

An Impact of Self-Recirculation Casing Treatment (SRCT) Configurations on Impeller Stall Margin and the Flow Field

2012 ◽  
Author(s):  
Yan Ma ◽  
Guang Xi ◽  
Guangkuan Wu
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Operating Conditions ◽  
Centrifugal Impeller ◽  
Flow Angle ◽  
Stall Margin ◽  
Casing Treatment ◽  
Swirl Velocity ◽  
Inlet Swirl ◽  
Unsteady Simulation

The present paper describes an investigation of stall margin enhancement and a detailed analysis of the impeller flow field due to self-recirculation casing treatment (SRCT) configuration of a high-speed small-size centrifugal impeller. The influence of different SRCT configurations on the impeller flow field at near-stall condition has been analyzed, highlighting the improvement in stall flow ability. This paper also discusses the influence of the SRCT configurations on the inlet flow angle, inlet swirl velocity and loss distribution in the impeller passage to understand the mechanism of the SRCT configurations in enhancing the stall margin of the impeller. The variation of the bleed flow rate at different operating conditions is also presented in this paper. Finally, the time-averaged unsteady simulation results at near-stall point are presented and compared with steady-state solutions.

Numerical Investigations of the Coupled Flow Through a Subsonic Compressor Rotor and Axial Skewed Slot

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Xingen Lu ◽  
Wuli Chu ◽  
Junqiang Zhu ◽  
Yangfeng Zhang
Keyword(s):  
Axial Flow ◽  
Tip Clearance ◽  
Stall Margin ◽  
Tip Clearance Flow ◽  
Casing Treatment ◽  
Axial Flow Compressor ◽  
Compressor Rotor ◽  
Clearance Flow ◽  
Flow Through ◽  
Flow Compressor

In order to advance the understanding of the fundamental mechanisms of axial skewed slot casing treatment and their effects on the subsonic axial-flow compressor flow field, the coupled unsteady flow through a subsonic compressor rotor and the axial skewed slot was simulated with a state-of-the-art multiblock flow solver. The computational results were first compared with available measured data, that showed the numerical procedure calculates the overall effect of the axial skewed slot correctly. Then, the numerically obtained flow fields were interrogated to identify the physical mechanism responsible for improvement in stall margin of a modern subsonic axial-flow compressor rotor due to the discrete skewed slots. It was found that the axial skewed slot casing treatment can increase the stall margin of subsonic compressor by repositioning of the tip clearance flow trajectory further toward the trailing of the blade passage and retarding the movement of the incoming∕tip clearance flow interface toward the rotor leading edge plane.

Numerical Investigation of Casing Treatment Mechanisms With a Conservative Mixed-Cell Approach

2003 ◽  
Author(s):  
H. Yang ◽  
D. Nuernberger ◽  
E. Nicke ◽  
A. Weber
Keyword(s):  
Operating Conditions ◽  
Coupled Flow ◽  
Mixed Cell ◽  
Stall Margin ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Grid Topology ◽  
The Face ◽  
Overall Efficiency

A conservative mixed-cell approach of second-order accuracy is presented and applied to investigate the mechanisms of a self-recirculating casing treatment coupled with a transonic compressor rotor. The mixed cell is a computational cell that may show up at the zonal interface boundary, the face of which is partially solid and partially fluid, if the azimuthal open area of casing treatment does not fully contact with the whole annulus of blade passage. The mixed-cell approach is essentially an extension of the conservative zonal approach by incorporating special mixed-cell handling at the zonal interface and it allows a great flexibility to the grid generation for the patched zones with the best grid topology. The mixed-cell approach is extremely useful for solving the unsteady interaction problems within turbomachinery and its application for simulating the coupled flow through the rotor and the casing treatment is reported. The calculated results and analysis reveal an effective stall margin extension of the casing treatment herein by weakening or even destroying the tip leakage vortex, and expose the different tip flow topologies between the cases with the casing treatment and with the untreated smooth wall. It is found that the casing treatment only slightly decreases the overall efficiency at the design point, but it is beneficial to the overall efficiency at the off-design operating conditions and it can improve the inflow conditions to the downstream stator blade row as well.

Experimental Investigation of the Steady and Unsteady Flow Field in a Single Stage Low Pressure Axial Compressor With a Circumferential Groove Casing Treatment

2010 ◽  
Author(s):  
N. Van de Wyer ◽  
B. Farkas ◽  
J. Desset ◽  
J. F. Brouckaert ◽  
J.-F. Thomas ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Flow Field ◽  
Unsteady Flow ◽  
Axial Compressor ◽  
Low Pressure ◽  
Fast Response ◽  
Single Stage ◽  
Compressor Stage ◽  
Casing Treatment ◽  
Circumferential Groove

This paper deals with the experimental investigation of the influence of a circumferential groove casing treatment on the performance and stability margin of a single stage low pressure axial compressor. The design of the compressor stage is representative of a booster stage for the new counter-rotating turbofan engine architecture and is characterized by unusually high loading and flow coefficients. The choice of the circumferential groove is described on the basis of a numerical parametric study on the number of grooves, the axial position, the depth and width of the groove. The experiments were performed at a Reynolds number corresponding to cruise conditions in the von Karman Institute closed loop high speed compressor test rig R4. The detailed performance characterization of the compressor stage with casing treatment was mapped at four operating points from choke to stall at design speed. The compressor stall limit was determined at several other off-design speeds. Detailed steady and unsteady measurements were performed to determine the flow field characteristics of the rotor and of the complete stage. Conventional pressure, temperature and directional probes were used along with fast response pressure sensors in the rotor casing and in the groove. Simultaneous traverses with a fast response total pressure probe were used to map the unsteady flow field at the rotor exit allowing an experimental capture of the tip leakage vortex path and extension through the rotor passage. A comparison of the flow features with and without casing treatment was performed and the results are discussed against 3D viscous computational predictions. The casing treatment did not present any improvement of the compressor stall margin but no significant performance degradation was observed either. The CFD predictions showed a good agreement with the measurements and their analysis supported the experimental results.

scholarly journals Recessed Casing Treatment Effects on Fan Performance and Flow Field

1995 ◽  
Author(s):  
C. S. Kang ◽  
A. B. McKenzie ◽  
R. L. Elder
Keyword(s):  
Flow Field ◽  
Axial Flow ◽  
Pressure Rise ◽  
Operating Efficiency ◽  
Flow Measurements ◽  
Blade Loading ◽  
Stall Margin ◽  
Casing Treatment ◽  
Stall Margin Improvement ◽  
Blade Tip

An experimental investigation to examine the influence of the vaned recess casing treatment on stall margin, operating efficiency and the flow field of a low speed axial flow fan with aerospace type blade loading is presented. Different geometrical designs of the vaned passages were examined. The best configuration resulted in a stall margin improvement of 67%, a significantly higher pressure rise in the stall region and insignificant change in peak efficiency. Detailed 3-D flow measurements in the endwall region and in the casing recess were carried out with a slanted hot-wire, providing some insight to the operation of the device. The results revealed that the stall margin improvement was largely due to the removal of flow from the blade tip to the recess, and the elimination of the growth of the stall region at the tip, which occurs at stall in the solid casing build.

Investigation of Blade Tip Interaction With Casing Treatment in a Transonic Compressor—Part II: Numerical Results

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
R. Schnell ◽  
M. Voges ◽  
R. Mönig ◽  
M. W. Müller ◽  
C. Zscherp
Keyword(s):  
Flow Field ◽  
Axial Compressor ◽  
Field Measurements ◽  
Phase Lag ◽  
Stall Margin ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Maximum Benefit ◽  
Coupling Procedure ◽  
Domain Phase

A single stage transonic axial compressor was equipped with a casing treatment consisting of 3.5 axial slots per rotor pitch in order to investigate its influence on stall margin characteristics, as well as on the rotor near tip flow field, both numerically and experimentally. Contrary to most other studies, a generic casing treatment (CT) was designed to provide optimal optical access in the immediate vicinity of the CT, rather than for maximum benefit in terms of stall margin extension. The second part of this two-part paper deals with the numerical developments and their validation, carried out in order to efficiently perform time-accurate casing treatment simulations. The numerical developments focus on the extension of an existing coupling algorithm in order to carry out unsteady calculations with any exterior geometry coupled to the main flow passage (in this case a single slot), having an arbitrary pitch. This extension is done by incorporating frequency domain, phase-lagged boundary conditions into this coupling procedure. Whereas the phase lag approach itself is well established and validated for standard rotor-stator calculations, its application to casing treatment simulations is new. Its capabilities and validation will be demonstrated on the given compressor configuration, making extensive use of the detailed particle image velocimetry flow field measurements near the rotor tip. Instantaneous data at all measurement planes will be compared for different rotor positions with respect to the stationary slots in order to evaluate the time-dependent interaction between the rotor and the casing treatment.

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