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.

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 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.

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.

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.

Effects of a Vane-Recessed Tubular-Passage Passive Stall Control Technique on a Multistage, Axial-Flow Compressor: Results of Tests on the First Stage With the Rear Stages Removed

2003 ◽  
Author(s):  
M. Akhlaghi ◽  
R. L. Elder ◽  
K. W. Ramsden
Keyword(s):  
Rotor Blade ◽  
Axial Flow ◽  
Control Technique ◽  
Maximum Efficiency ◽  
Stall Margin ◽  
Casing Treatment ◽  
Axial Flow Compressor ◽  
Stall Margin Improvement ◽  
Blade Tip ◽  
Flow Compressor

The objective of the current study was to investigate the effect of casing treatment on a multistage axial flow compressor. The main purpose of the investigation was to extend the range and operability of multistage axial compressors. The study seeks to establish whether a vane-recessed tubular-passage casing-treatment could provide beneficial stall margin improvement, without sacrificing the efficiencies of the compressor with the restricted space available for the treatment. A casing treatment that consisted of three parts: an outer casing ring, with a tubular shaped passage on the inside, a set of 120 evenly spaced curved vanes, and then a shroud or inner ring was developed from two initial designs. The casing treatment, manufactured from high quality acrylic, was positioned upstream and partly covering the tip of the first stage rotor blades. The casing treatment was tested on the first stage of a three-stage low-speed compressor with inlet guide vanes with the rear two stages removed. The rotor blade tip axial chord exposure had a significant impact on the effectiveness of the casing treatment. Seven compressor configuration incorporating casing treatments of 23.2%, 33.3%, 43.4%, 53.5%, 63.6%, 73.7% and 83.8% rotor exposure were tested. The results showed significant improvements in stall margin in all exposures and insignificant efficiency sacrifices in some exposures. Nearly 29% of stall margin improvement in terms of the corrected mass flow rate was achieved with 33.3% rotor blade tip axial chord exposure. The compressor build with 53.5% rotor exposure was the best configuration in terms of maximum efficiency gain. In terms of peak pressure rise coefficients the compressor configuration with a casing treatment of 63.6% exposure was the best design. The results also suggest that the vane-recessed tubular-passage casing treatment designed as part of this research, in most instances enabled the stall conditions in the compressor to become progressive rather than abrupt.

scholarly journals Flow mechanism of affecting an axial flow compressor performance and stability with cross-blade slot casing treatments

2018 ◽  
Vol 233 (1) ◽  
pp. 17-36 ◽  
Author(s):  
HaoGuang Zhang ◽  
XuDong Zhang ◽  
YanHui Wu ◽  
WuLi Chu ◽  
HaiYang Kuang
Keyword(s):  
Axial Flow ◽  
Low Energy ◽  
Peak Efficiency ◽  
Stall Margin ◽  
Casing Treatment ◽  
Flow Loss ◽  
Stall Margin Improvement ◽  
And Performance ◽  
Flow Compressor ◽  
Casing Treatments

The objective of this study is to evaluate the effect of cross-blade slot casing treatment on the stability and performance of an axial flow compressor rotor. The experimental and unsteady calculated results both show that cross-blade slot casing treatment can generate about 22% stall margin improvement, and the compressor peak efficiency is reduced by about 13%. The detailed flow-field analyses indicate that the sucked and injected flow caused by the slots of cross-blade slot casing treatment can restrain the rotor tip passage blockage, which is made by the low energy tip clearance leakage vortex. When cross-blade slot casing treatment is applied, not only the rotor wheel flange work becomes lower in most of the rotor blade span, but also the flow loss in the blade tip passage becomes fairly large due to the strong interaction between the mainstream and the injected flows made by the slots. As a result, the compressor total pressure ratio and efficiency for cross-blade slot casing treatment are reduced obviously. Three kinds of new cross-blade slot casing treatment were designed according to the previous successful experience and investigated in this paper. The numerical results show that the new three cross-blade slot casing treatments both generate about 54% stall margin improvement at the cost of minor peak efficiency. For one new cross-blade slot casing treatment (CSCT2), the compressor peak efficiency is reduced by about 0.3%. The low energy TLV, which is present for cross-blade slot casing treatment, is removed by the strong sucked flow made by CSCT2. Moreover, the interaction between the mainstream and the injected flows caused by CSCT2 becomes weak obviously, and the corresponding flow loss is reduced greatly. Hence, the compressor stability and performance with CSCT2 are higher than those with cross-blade slot casing treatment.

Influence of Rain Ingestion on the Endwall Treatment in an Axial Flow Compressor

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Jichao Li ◽  
Juan Du ◽  
Mingzhen Li ◽  
Feng Lin ◽  
Hongwu Zhang ◽  
...  
Keyword(s):  
Rotor Blade ◽  
Axial Flow ◽  
Pressure Rise ◽  
Water Film ◽  
Stall Margin ◽  
Axial Flow Compressor ◽  
Water Ingestion ◽  
Blade Row ◽  
Flow Compressor ◽  
The Stability

The effects of water ingestion on the performance of an axial flow compressor are experimentally studied with and without endwall treatment. The background to the work is derived from the assessment of airworthiness for an aero-engine. The stability-enhancing effects with endwall treatments under rain ingestion are not previously known. Moreover, all the endwall treatments are designed under dry air conditions in the compressor. Water ingestion at 3% and 5% relative to the design mass flow proposed in the airworthiness standard are applied to initially investigate the effects on the performance under smooth casing (SC). Results show that the water ingestions are mainly located near the casing wall after they move through the rotor blade row. The pressure rise coefficient increases, efficiency declines, and torque increases under the proposed water ingestion. The increase of the inlet water increases the thickness of the water film downstream the rotor blade row and aggravates the adverse effects on the performances. Subsequently, three endwall treatments, namely circumferential grooves, axial slots, and hybrid slots–grooves, are tested with and without water ingestion. Compared with no water ingestion, the circumferential grooves basically have no resistance to the water ingestion. The axial slots best prevent the drop of the pressure rise coefficient induced by water ingestion, and hybrid slots–grooves are the second-best place owing to the contribution of the front axial slots. Therefore, the hybrid slots–grooves can not only extend the stall margin with less efficiency penalty compared with axial slots, but also prevent rain ingestion from worsening the compressor performance.

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.

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