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

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.

Performance Characterization of the Effect of Axial Positioning of Bend Skewed Casing Treatment Retrofitted to a Transonic Axial Flow Compressor

2014 ◽  
Author(s):  
Dilipkumar B. Alone ◽  
Subramani Satish Kumar ◽  
Shobhavathy Thimmaiah ◽  
Janaki Rami Reddy Mudipalli ◽  
A. M. Pradeep ◽  
...  
Keyword(s):  
Axial Flow ◽  
Single Stage ◽  
Compressor Stage ◽  
Stall Margin ◽  
Casing Treatment ◽  
Axial Flow Compressor ◽  
Transonic Compressor ◽  
Maximum Improvement ◽  
Flow Compressor ◽  
Stage Efficiency

The performance of an aero-engines to a large extend depends on the performance behavior of axial flow compressors and is restricted by the compressor instabilities like rotating stall and surge. In the present study, attempts have been made to design and develop the bend skewed casing treatment geometries with lower porosities to improve the stable operating range of single stage axial flow compressor. Experimental investigations were undertaken to study the impact of axial position of one of the casing treatment geometry on the single stage transonic axial flow compressor. The transonic compressor used for the current experimental studies has a stage total to total pressure ratio of 1.35, corrected mass flow rate of 22 kg/s at an operating speed of 12930 rpm. The compressor stage steady and unsteady state response for 20%, 40%, 60% and 100% axial chord coverage relative to the rotor tip chord of the bend skewed casing treatment with a porosity of 33% was studied experimentally. The objective was to identify the optimum axial location; which will give maximum improvement in the stall margin with minimal loss of compressor stage efficiency. Through an experimental study it was observed that the axial location of bend skewed casing treatment plays a very crucial role in governing the performance of the transonic compressor. For all the investigated axial coverages, compressor stall margin increases but the optimum performance in terms of stall margin improvement and efficiency gains were observed at 20% and 40% of the rotor chord. This trend shows good agreement with existing published literature. An improvement of 31.7% in the stall margin with an increase in the stage efficiency was obtained at one of the axial coverage. Maximum improvement of 37% in the stall margin above the solid casing was noticed at 60% axial coverage. The stalling characteristics of the compressor stage also changes with the axial positions. In the presence of solid casing the nature of stall was abrupt and stalls cells travels at half the rotor speed. The blade element performance also studied at the rotor exit using pre-calibrated aerodynamic probe.

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.

On Understanding the Effect of Plenum Chamber of a Bend Skewed Casing Treatment on the Performance of a Transonic Axial Flow Compressor

2014 ◽  
Author(s):  
Dilipkumar B. Alone ◽  
Subramani Satish Kumar ◽  
Shobhavathy Thimmaiah ◽  
Janaki Rami Reddy Mudipalli ◽  
A. M. Pradeep ◽  
...  
Keyword(s):  
Axial Flow ◽  
Single Stage ◽  
Compressor Stage ◽  
Stall Margin ◽  
Casing Treatment ◽  
Plenum Chamber ◽  
Axial Flow Compressor ◽  
Chamber Volume ◽  
Stable Operating ◽  
Flow Compressor

Bend skewed casing treatment was designed to improve the stable operating range of single stage transonic axial flow compressor and also to understand the effects of its plenum chamber volume on the performance. This paper presents the original experimental research work undertaken to study the effect of plenum chamber depth and thus its volume on the performance of single stage transonic axial flow compressor coupled with the bend skewed casing treatment. The bend skewed casing treatment with porosity of 33% was selected for the present experimental study. The bend skewed casing treatment has slot width equal to the maximum thickness of the rotor blade. The casing treatment geometry has an axial front segment and a 45° staggered rear segment following the blade tip stagger. Both the segments were skewed by 45° in the radial plane, in such a way that the flow emerging from the casing slots would do so with swirl contrary to the direction of rotor rotation. The plenum chamber which can also be called as stagnation zone exists above the skewed slots. The plenum chamber has an axial length equal to the axial length of the casing treatment slots. The maximum depth of the plenum chamber was 11 mm and which was equal to the depth of bend skewed casing slots. The depth of plenum chamber was varied from zero, half the slot depth, and equal to slot depth in order to get variable volume. The porosity and axial location of the casing treatment relative to the rotor tip chord were chosen from the earlier experimental programs on effect of bend skewed casing treatment porosities and axial coverages for the present compressor stage. Optimum performance of the transonic compressor stage was obtained at 20% and 40% axial coverages and for 33% porosity configurations. The axial coverages of 20% and 40% were chosen for the present study to understand the effects of plenum chamber volume on the performance of single stage transonic axial flow compressor. The performance of the compressor stage with solid casing and casing treatment with different plenum volume was obtained and compared at different operating speeds. The compressor performance was derived for the fixed casing treatment porosity of 33% and for three different configurations of plenum chamber volumes at two different axial coverages. Experimental investigations reveal that the plenum chamber volume does have an impact on the stable operating range of the compressor. The compressor stall margin improves with increase in the plenum chamber volume. Bend skewed casing treatment coupled with plenum chamber of depths equal to the slots depth results in maximum stall margin improvement of 37.62% as compared to 26.40% without plenum chamber over the solid casing at 40% axial coverage. For this combination 0.8% improvement in the peak stage efficiency above the solid casing was noticed at 60% design speed.

Flow Studies on a Single Stage Transonic Axial Flow Compressor Retrofitted With Circumferential Grooves and Varied Rotor-Stator Axial Gap

2017 ◽  
Author(s):  
Anand P. Darji ◽  
Dilipkumar Bhanudasji Alone ◽  
Chetan S. Mistry
Keyword(s):  
Numerical Study ◽  
Computational Study ◽  
Axial Flow ◽  
Single Stage ◽  
Experimental Results ◽  
Stall Margin ◽  
Axial Flow Compressor ◽  
Transonic Compressor ◽  
Stall Margin Improvement ◽  
Flow Compressor

A transonic axial flow compressor undergoes severe vibrations due to instabilities like stall and surge when it operates at lower mass flow rate in the absence of any control devices. In present study, the attempt was made to understand the combine impact of circumferential casing grooves (CCG) of constant aspect ratio and different axial spacing between rotor and stator on the operating stability of single stage transonic axial compressor and that of rotor alone using numerical simulation. The optimum rotor-stator gap in the presence of grooved casing treatment was identified. The steady state numerical analysis was performed by using three-dimensional Reynolds Average Navier-Stokes equation adapting shear stress transport (SST) k-ω turbulence model. The study is reported in two sections. First section includes the detailed numerical study on baseline case having smooth casing wall (SCW). The computational results were validated with the experimental results available at Propulsion Division of CSIR-NAL, Bangalore. The computational study shows good agreement with experimental results. The second section comprises the effects of optimum designs of CCG and various axial spacing on the stall margin improvement of transonic compressor. Current computational study shows that the axial spacing between rotor and stator is an important parameter for improvement in stall margin not only for SCW but also for CCG. Therefore, the highest stall margin improvement of 9% has achieved for 75% axial spacing.

Numerical analysis of the effects of circumferential groove casing suction in a counter-rotating axial flow compressor

2020 ◽  
pp. 095765092095169
Author(s):  
Tian Liang ◽  
Bo Liu ◽  
Stephen Spence ◽  
Liying Jiao
Keyword(s):  
Axial Flow ◽  
Main Flow ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Stall Margin ◽  
Tip Leakage ◽  
Axial Flow Compressor ◽  
Circumferential Groove ◽  
Flow Compressor ◽  
The Impact

To extend the current understanding of the circumferential groove casing suction applied to a counter-rotating axial flow compressor, the impact of different axial locations of the circumferential suction groove on the characteristics of the tip leakage flow (TLF) and the corresponding physical mechanisms producing the stability enhancement have been studied based on validated numerical simulations. The results show that the optimal location for the suction groove is at around 20% axial chord, which demonstrated a high potential for reducing additional stall mass flow coefficient with about 8.4% increment in the stall margin. After the casing suction groove was applied, the interface between the incoming main flow and TLF was pushed significantly downstream in the second rotor. The blade loading in the region below the groove, the tip leakage flow angle and the reversed axial momentum flux injected into main flow passage through the tip gap were all reduced, which contributed to the stall margin improvement. Detailed analysis of the tip leakage flow structures showed that the TLF originating from different chord locations played different roles in the stall inception process. It was found to be more effective to improve stall margin and adiabatic efficiency by controlling the front part of the TLF, which was most sensitive.

Numerical Studies on Effect of Stepped Tip Clearance Height on the Performance of Single Stage Transonic Axial Flow Compressor

2013 ◽  
Author(s):  
Pritam Batabyal ◽  
Dilipkumar B. Alone ◽  
S. K. Maharana
Keyword(s):  
Numerical Study ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Axial Flow ◽  
Single Stage ◽  
Tip Clearance ◽  
Baseline Model ◽  
Axial Flow Compressor ◽  
Design Speed ◽  
Flow Compressor

This paper presents a numerical case study of various stepped tip clearances and their effect on the performance of a single stage transonic axial flow compressor, using commercially available software ANSYS FLUENT 14.0. A steady state, implicit, three dimensional, pressure based flow solver with SST k-Ω turbulence model has been selected for the numerical study. The stepped tip clearances have been compared with the baseline model of zero tip clearance at 70% and 100 % design speed. It has been observed that the compressor peak stage efficiency and maximum stage pressure ratio decreases as the tip clearances in the rear part are increased. The stall margin also increases with increase in tip clearance compared to the baseline model. An ‘optimum’ value of stepped tip clearance has been obtained giving peak stage compressor performance. The CFD results have been validated with the earlier published experimental data on the same compressor at 70% design speed.

Effect of hub clearance of cantilever stator on aerodynamic performance and flow field of a transonic axial-flow compressor

2021 ◽  
pp. 095441002199370
Author(s):  
Botao Zhang ◽  
Bo Liu ◽  
Xiaochen Mao ◽  
Hejian Wang
Keyword(s):  
Flow Field ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Aerodynamic Performance ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Stall Margin ◽  
Axial Flow Compressor ◽  
Stator Blade ◽  
Flow Compressor

To investigate the effect of hub clearance of cantilever stator on the aerodynamic performance and the flow field of the transonic axial-flow compressor, the performance of single-stage compressors with the shrouded stator and cantilever stator was studied numerically. It is found that the hub corner separation on the stator blade suction surface (SS) was modified by introducing the hub leakage flow. The separation vortex on the SS of the stator blade root at about 10% axial chord length caused by the interaction of the shock wave and boundary layer was also controlled. Compared with the tip clearance size of the rotor blade, the stator hub clearance size (HCS) has a much less effect on the overall aerodynamic performance of the compressor, and there is no obvious effect on the flow field in the upstream blade row. With the increase of HCS, the leakage loss and the blockage degree in the flow field near the stator hub are increased and further make the adiabatic efficiency and the total pressure ratio of the compressor gradually decrease. Meanwhile, the stall margin of the compressor was changed slightly, but the response of the stall margin to the change of the HCS is nonlinear and insensitive. The stator hub leakage flow (HLF) can not only change the flow field near the hub but also redistribute the flow law within the range of the entire blade span. It will contribute to further understand the mechanism of the HLF and provide supports for the design of the cantilever stator of transonic compressors.

Influence of Blade Tip Surface Roughness On the Performance of a Single Stage Axial Flow Compressor

2021 ◽  
Author(s):  
Pradyumna Kodancha ◽  
Pramod Salunkhe
Keyword(s):  
Surface Roughness ◽  
Axial Flow ◽  
Single Stage ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Axial Flow Compressor ◽  
Blade Tip ◽  
Flow Compressor

Abstract Numerical investigations are carried out in a single-stage subsonic axial flow compressor to unravel the influence of blade tip surface roughness on the tip leakage flow characteristics and hence the compressor performance. The studies were carried out at different tip clearance of 0.38?, 0.77?, 1.15? and 1.54? and blade tip surface roughness of 0.31? and 0.62?. The tip clearance of 0.38? with blade tip surface roughness of 0.62? resulted in the highest stall margin and pressure rise of 20.3% and 4.3%, respectively. The compressor blade loading was found to be improved by 5.9% after incorporating the blade tip surface roughness. The iso-surfaces of vorticity contour plotted using the Q-criterion showed the reduction in strength of the tip leakage vortex. The tip leakage trajectory was found to be shifted towards the suction surface of the blade for the blade tip with surface roughness. This positive alteration in the tip leakage flow structure led to the improved performance for the blade tip with surface roughness.

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

2006 ◽  
Vol 220 (12) ◽  
pp. 1785-1796 ◽  
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.

An Experimental Investigation About the Effect of the Partial Casing Treatment on a Transonic Axial-Flow Compressor Performance Under Inlet Distortion

2012 ◽  
Author(s):  
Maoyi Li ◽  
Wei Yuan ◽  
Xizhen Song ◽  
Yajun Lu ◽  
Zhiping Li ◽  
...  
Keyword(s):  
Total Pressure ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Peak Efficiency ◽  
Stall Margin ◽  
Casing Treatment ◽  
Axial Flow Compressor ◽  
Inlet Distortion ◽  
Flow Compressor ◽  
Total Pressure Ratio

The traditional annulus casing treatment often pays the price of lowered efficiency for improving the stall margin of a compressor under inlet distortion. In view of the unsymmetry of the inlet flow-field of compressors, partial casing treatment was used to control the flow in a transonic axial-flow compressor with arc-skewed-slots deployed at different circumferential positions under inlet distortion. The experimental results indicate that when the partial casing treatment is arranged on the undistorted and distorted sectors, the stall margin is enhanced by 8.02%, with the relative peak efficiency improved simultaneously by 2.143%, compared with the case of solid casing at 98% rotating speed. By contrast, the traditional casing treatment increases the stall-margin by 23.13%, but decreases the relative peak efficiency by 0.752%. By analyzing dynamic and static experimental data, the mechanism underlying the partial casing treatment was also studied in detail here. The disturbances of inlet flow were restrained by annulus casing treatment, nevertheless the total pressure ratio was decreased obviously in the distorted sector. As a result, the stall-margin is improved, but the relative peak efficiency is decreased too. When the partial casing treatment was arranged on the undistortded and distorted sectors, the stall disturbances was thereby restrained. So the stall margin was enhanced. In addition, the total pressure ratio was improved by the partial casing treatment in the distorted and transition sectors, and thus the relative peak efficiency was also increased markedly.

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