Influence of SPS casing treatment on axial flow compressor subjected to radial pressure distortion

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.

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Experimental Investigation on the Effect of Porosity of Bend Skewed Casing Treatment on a Single Stage Transonic Axial Flow Compressor

Volume 2A: Turbomachinery ◽

10.1115/gt2014-26102 ◽

2014 ◽

Cited By ~ 1

Author(s):

Dilipkumar B. Alone ◽

Subramani Satish Kumar ◽

Shobhavathy Thimmaiah ◽

Janaki Rami Reddy Mudipalli ◽

A. M. Pradeep ◽

...

Keyword(s):

Experimental Investigation ◽

Axial Flow ◽

Compressor Stage ◽

Casing Treatment ◽

Operating Range ◽

Axial Flow Compressor ◽

Transonic Compressor ◽

Stable Operating ◽

Flow Compressor ◽

Casing Treatments

A bend skewed casing treatment was designed, to study the influence of one of its geometrical parameter porosity on the stable performance of single stage transonic axial flow compressor. The compressor was designed for the stage total-to-total pressure ratio of 1.35, corrected mass flow rate of 22 kg/s at corrected design speed of 12930 RPM. Bend skewed casing treatment has an axial inlet segment till 50% of the total length and rear segment that is skewed by 45° in the direction of the rotor tip section stagger. Both the sections were oriented at a skew angle of 45° to the radial plane such that the flow exiting the slot is in counter-clockwise direction to that of the rotor direction. The casing treatment slot width was equal to the maximum thickness of the rotor blades. Three casing treatment configurations were identified for the current experimental investigation. All the treatment geometries considered for the experimental research have lower porosities than reported in the open literatures. The effect of the porosity parameter on the performance of transonic compressor stage was evaluated at two axial coverages of 20% and 40% relative to the rotor tip axial chord. Performance maps were obtained for the solid casing and casing treatment with three different porosities. Comparative studies were carried out and experimental results showed a maximum of 65% improvement in the stable operating range of the compressor for one of the treatment configurations. It was also observed that the stable operating range of the compressor increases with an increase in the casing treatment porosity. All the casing treatment configurations showed that the compressor stall occurs at lower mass flows as compared to the solid casing. Compressor stage peak efficiency shows significant degradations with increase in the porosity as compared to solid casing. Detailed blade element performances were also obtained using calibrated multi-hole aerodynamic probe. Comparative variations of flow parameters like absolute flow angle, Mach number were studied at full flow and near stall conditions for the solid casing and casing treatment configurations. Hot wire measurements show very high fluctuation in the inlet axial velocity in the presence of solid casing as compared to casing treatments. Experimental investigation revealed that the porosity of the casing treatments has strong influence on the transonic compressor stage performance.

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The Effects on Stability, Performance, and Tip Leakage Flow of Recirculating Casing Treatment in a Subsonic Axial Flow Compressor

Volume 2A: Turbomachinery ◽

10.1115/gt2016-56756 ◽

2016 ◽

Cited By ~ 2

Author(s):

Wei Wang ◽

Wuli Chu ◽

Haoguang Zhang ◽

Yanhui Wu

Keyword(s):

Axial Flow ◽

Leakage Flow ◽

Tip Leakage Flow ◽

Tip Leakage Vortex ◽

Stall Inception ◽

Casing Treatment ◽

Tip Leakage ◽

Axial Flow Compressor ◽

Overall Performance ◽

Flow Compressor

Recirculating casing treatment (RCT) was studied in a subsonic axial flow compressor experimentally and numerically. The RCT was parameterized with the injector throat height and circumferential coverage percentage (ccp) to investigate its influence on compressor stability and on the overall performance in the experimentation. The injector throat height varied from 2 to 6 times the height of the rotor tip clearance, and the ccp ranged from 8.3% to 25% of the casing perimeter. Various RCT configurations were achieved with a modular design procedure. The rotor casing was instrumented with fast-response pressure transducers to detect the stall inception, rotational speed of stall cells, and pressure flow fields. Whole-passage unsteady simulations were also implemented for the RCT and solid casing to understand the flow details. Results indicate that both the compressor stability and overall performance can be improved through RCT with appropriate geometrical parameters. The effect of injector throat height on the stability depends on the choice of ccp, i.e., interaction effect exists. In general, the RCT with a moderate injector throat height and a large circumferential coverage is the optimal choice. Phase-locked pattern of the casing wall pressure reveals a weakened tip leakage vortex under the effect of RCT compared with the solid casing. The numerical results show that the RCT has a substantial effect on tip blockage even when the blade passages break away from the domain of RCT. The reduction of tip blockage induced by the tip leakage vortex is the main reason for the extension of stable operation range. The unsteadiness of double-leakage flow is detected both in the experiment and in numerical simulations. The pressure fluctuations caused by double-leakage flow are depressed with RCT. This observation indicates reduced losses related with the double-leakage flow. Although the stall inception is not changed by implementing RCT, the stall pattern is altered. The stall with two cells is detected in RCT compared with the solid casing with only one stall cell.

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Aerodynamic behavior of a transonic axial flow compressor stage with self-recirculating casing treatment

Aerospace Science and Technology ◽

10.1016/j.ast.2021.106587 ◽

2021 ◽

pp. 106587

Author(s):

S Satish Kumar ◽

Dilipkumar Bhanudasji Alone ◽

Shobhavathy M Thimmaiah ◽

Janaki Rami Reddy Mudipalli ◽

Lakshya Kumar ◽

...

Keyword(s):

Axial Flow ◽

Compressor Stage ◽

Casing Treatment ◽

Axial Flow Compressor ◽

Flow Compressor

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Experimental study of self-recirculating casing treatment in a subsonic axial flow compressor

Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy ◽

10.1177/0957650916673266 ◽

2016 ◽

Vol 230 (8) ◽

pp. 805-818 ◽

Cited By ~ 2

Author(s):

Wei Wang ◽

Wuli Chu ◽

Haoguang Zhang ◽

Yanhui Wu

Keyword(s):

Axial Flow ◽

Operating Conditions ◽

Geometrical Parameters ◽

Flow Angle ◽

Casing Treatment ◽

Axial Flow Compressor ◽

Blade Tip ◽

Overall Performance ◽

Flow Compressor ◽

Casing Treatments

Parametric studies of recirculating casing treatment were experimentally performed in a subsonic axial flow compressor. The recirculating casing treatment was parameterized with injector throat height, injection position, and circumferential coverage percentage. Eighteen recirculating casing treatments were tested to study the effects on compressor stability and on the compressor overall performance at three blade speeds. The profiles of recirculating casing treatment were optimized to minimize the losses generated by air recirculation. In the experiment, the stalling mass flow rate, total pressure ratio, and adiabatic efficiency of the compressor were measured to study the steady-state effects on the compressor performance of recirculating casing treatments, and static pressure disturbances on the casing wall were monitored to study the influence on stall dynamics. Results indicate that both the compressor stability and overall performance can be improved through recirculating casing treatment with appropriate geometrical parameters for all the test speeds. The influence on stall margin of one geometric parameter often depends on the choice of others, i.e. the interaction effects exist. In general, the recirculating casing treatment with a moderate injector throat and a large circumferential coverage is the optimal choice to enhance compressor stability. The injector of recirculating casing treatment should be placed upstream of the blade tip leading edge and the injector throat height should be lower than four times the rotor tip gap for the benefits of compressor efficiency. At 71% speed, the blade tip loading is decreased through recirculating casing treatment at the operating condition of near peak efficiency and increased near stall. Moreover, the outlet absolute flow angle is reduced in the tip region and enhanced at lower blade spans for both operating conditions. The stall inceptions are not changed with the implementation of recirculating casing treatment for all the test speeds, but the stall patterns are altered at 33% and 53% speeds, i.e. the stall with two cells is detected in the recirculating casing treatment compared with the solid casing with only one stall cell.

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Numerical analysis of the circumferential grooves casing treatment in a counter-rotating axial flow compressor

Applied Thermal Engineering ◽

10.1016/j.applthermaleng.2017.11.044 ◽

2018 ◽

Vol 130 ◽

pp. 29-39 ◽

Cited By ~ 14

Author(s):

Xiaochen Mao ◽

Bo Liu ◽

Hang Zhao

Keyword(s):

Numerical Analysis ◽

Axial Flow ◽

Casing Treatment ◽

Axial Flow Compressor ◽

Flow Compressor

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Experimental and numerical investigation of a subsonic compressor with bend-skewed slot-casing treatment

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1243/0954406jmes385 ◽

2006 ◽

Vol 220 (12) ◽

pp. 1785-1796 ◽

Cited By ~ 14

Author(s):

X Lu ◽

W Chu ◽

Y Zhang ◽

J Zhu

Keyword(s):

Rotor Blade ◽

Axial Flow ◽

Efficiency Gain ◽

Stall Margin ◽

Blade Passage ◽

Casing Treatment ◽

Axial Flow Compressor ◽

Compressor Rotor ◽

Flow Compressor ◽

Isentropic Efficiency

On the basis of the test results of discrete axial and blade angle slot casing treatment, a new type of casing treatment was designed for a subsonic axial flow compressor rotor by optimizing various geometry parameters. To obtain a wide operating range and to minimize penalties in terms of isentropic efficiency, seven compressor configurations incorporating casing treatments of 0, 16.6, 33.3, 50, 66.6, 83.3, and 100 per cent rotor exposures were experimentally investigated. The results showed that significant improvements in stall margin are possible in all exposures and insignificant isentropic efficiency sacrifices are recorded in some exposures. Nearly 21.43 per cent stall margin improvement in terms of the corrected mass flow-rate was achieved with 33.3 per cent rotor blade tip axial chord exposure. The compressor built with 16.6 per cent rotor exposure was the best configuration in terms of maximum isentropic efficiency gain. The second issue of the paper was to offer a contribution to the understanding of the physical mechanism by which bend-skewed slot-casing treatment improves stall margin under subsonic conditions. By applying a concept similar to ‘Domain scaling’ approach (as often used in multistage turbomachinery flow-fields) to the interface between the rotor blade passage and end-wall treatments, a time-dependent three-dimensional numerical simulation was performed for the subsonic axial-flow compressor rotor with bend-skewed slot-casing treatment. The numerical results agreed well with the available experimental results. Detailed analyses of the coupled flow through bend-skewed slot-casing treatment and rotor blade passage under subsonic conditions led to some preliminary conclusions as to the flow physics involved in the stall margin improvements afforded by the use of bend-skewed slot-casing treatment.

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Numerically Understand the Combined Effect of Tip Clearance and Circumferential Grooves Casing Treatment on the Performance of Single Stage Transonic Axial Flow Compressor

ASME 2015 Gas Turbine India Conference ◽

10.1115/gtindia2015-1210 ◽

2015 ◽

Author(s):

Mitesh Goswami ◽

Dilipkumar Bhanudasji Alone ◽

Harish S. Choksi

Keyword(s):

Axial Flow ◽

Single Stage ◽

Tip Clearance ◽

Combined Effect ◽

Stall Margin ◽

Casing Treatment ◽

Axial Flow Compressor ◽

Circumferential Groove ◽

Flow Compressor ◽

Stage Efficiency

This paper deals with the numerical studies on the combined effect of tip clearance and axisymmetric circumferential grooves casing treatment (CGCT) on the overall performance and stall margin of a single stage transonic axial flow compressor. Steady state numerical analysis was carried out by solving three dimensional Reynolds-averaged-Navier-Stokes (RANS) Equations using the Shear Stress Transport (SST) k-ω Turbulence Model. The numerical stall inception point was identified from the last converged point by the convergence criteria, and the stall margin was numerically predicted. Additionally, the stall margin and the isentropic peak stage efficiencies of the circumferential casing grooves with various tip clearances were compared and evaluated in order to explore the influence of the tip clearance. Results obtained were compared with those obtained on the baseline compressor with the smooth casing (SC). Further computational studies were conducted to study the role of the tip leakage flow in axial compressor in triggering the stall. The relationship between the tip clearance flow, flow field and surge margin extension from circumferential groove casing treatment with various rotor tip clearances were studied numerically. The application of the circumferential groove casing treatment with varying clearance leads to significant improvement in the operating stability of compressor with slight reduction in the isentropic peak stage efficiency for small tip clearances, whereas there was slight increment in the isentropic peak stage efficiency at higher tip clearance of 2.5 mm.

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Mechanism study of performance enhancement in a subsonic axial flow compressor with recirculating casing treatment

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410016687140 ◽

2017 ◽

Vol 232 (4) ◽

pp. 680-693 ◽

Cited By ~ 5

Author(s):

Wei Wang ◽

Wuli Chu ◽

Haoguang Zhang

Keyword(s):

Performance Enhancement ◽

Axial Flow ◽

Passage Time ◽

High Energy ◽

Leakage Flow ◽

Mechanism Study ◽

Casing Treatment ◽

Axial Flow Compressor ◽

Flow Compressor ◽

Compressor Efficiency

The improvements in both compressor efficiency and stability have been observed in a subsonic axial flow compressor with recirculating casing treatment. The study aims to understand the underlying flow mechanisms of the beneficial effect on the compressor efficiency of recirculating casing treatment. The recirculating casing treatment was investigated experimentally and numerically. In the experiment, static pressure fluctuations over the rotor tip were measured with fast-response pressure transducers. Whole-passage time-accurate simulations were also implemented to help in understanding the flow details. The unsteadiness of double-leakage flow and its effect on the loss generated at the rotor tip were discussed in detail for the solid casing. The effect of recirculating casing treatment on the double-leakage flow related loss was subsequently investigated. The results indicate that the double leakage flow is a main loss source in the rotor tip region. The double-leakage flow is completely unsteady, which induces a cyclical fluctuation of the amount of loss generated in the rotor tip region for the solid casing. With the recirculating casing treatment installed, the high-energy jet created in recirculating loops changes the unsteady characteristics of double-leakage flow by getting it diffused over the rotor tip gap along the chordwise direction, which results in the loss fluctuation that is dominated by the high-energy jet rather than the unsteadiness of double-leakage flow. The double-leakage flow is also pushed downstream by the jet and the amount is reduced when it passes through the recirculating loops. The effect of recirculating casing treatment on the double-leakage flow is primarily responsible for the improvement in the compressor efficiency.

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