Application of Casing Circumferential Grooves for Improved Stall Margin in a Transonic Axial Compressor

2002 ◽  
Author(s):  
D. C. Rabe ◽  
C. Hah
Keyword(s):  
Incidence Angle ◽  
Axial Compressor ◽  
Numerical Procedure ◽  
Leading Edge ◽  
Navier Stokes ◽  
Stall Margin ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Flow Mechanisms ◽  
Groove Configurations

Experimental and numerical investigations were conducted to study the fundamental flow mechanisms of circumferential grooves in the casing of a transonic compressor and their influence on compressor stall margin. Three different groove configurations were tested in a highly loaded transonic compressor. Experimental results show that circumferential grooves increase the stall margin of the compressor at the tested operating condition. Grooves with a much smaller depth than conventional designs are shown to be similarly effective in increasing the stall margin. Steady-state Navier-Stokes analyses were performed to study flow structures associated with each casing treatment. The numerical procedure calculates the overall effects of the circumferential grooves correctly. Detailed investigation of calculated flow fields indicates that losses are generated by interaction between the main passage flow and flow exiting the grooves. The grooves increase the stall margin by reducing the flow incidence angle on the pressure side of the leading edge, despite an overall increase in the endwall boundary layer thickness. This is due to complex interaction of the main passage flow with the additional radial and tangential flows created by the grooves.

Influencing Parameters of Tip Blowing Interacting With Rotor Tip Flow

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Cyril Guinet ◽  
André Inzenhofer ◽  
Volker Gümmer
Keyword(s):  
Geometric Model ◽  
Axial Compressor ◽  
Axial Flow ◽  
Navier Stokes ◽  
Axial Position ◽  
Design Parameters ◽  
Stall Margin ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Casing Treatments

The design space of axial-flow compressors is restricted by stability issues. Different axial-type casing treatments (CTs) have shown their ability to enhance compressor stability and to influence efficiency. Casing treatments have proven to be effective, but there still is need for more detailed investigations and gain of understanding for the underlying flow mechanism. Casing treatments are known to have a multitude of effects on the near-casing 3D flow field. For transonic compressor rotors, these are more complex, as super- and subsonic flow regions alternate while interacting with the casing treatment. To derive design rules, it is important to quantify the influence of the casing treatment on the different tip flow phenomena. Designing a casing treatment in a way that it antagonizes only the deteriorating secondary flow effects can be seen as a method to enhance stability while increasing efficiency. The numerical studies are carried out on a tip-critical rotor of a 1.5-stage transonic axial compressor. The examined recirculating tip blowing casing treatment (TBCT) consists of a recirculating channel with an air off-take above the rotor and an injection nozzle in front of the rotor. The design and functioning of the casing treatment are influenced by various parameters. A variation of the geometry of the tip blowing, more specifically the nozzle aspect ratio, the axial position, or the tangential orientation of the injection port, was carried out to identify key levers. The tip blowing casing treatment is defined as a parameterized geometric model and is automatically meshed. A sensitivity analysis of the respective design parameters of the tip blowing is carried out on a single rotor row. Their impact on overall efficiency and their ability to improve stall margin are evaluated. The study is carried out using unsteady Reynolds-averaged Navier–Stokes (URANS) simulations.

scholarly journals Numerical Optimization of a Stall Margin Enhancing Recirculation Channel for an Axial Compressor

Fluids ◽  
2019 ◽  
Vol 4 (2) ◽  
pp. 88
Author(s):  
Motoyuki Kawase ◽  
Aldo Rona
Keyword(s):  
High Speed ◽  
High Performance ◽  
Fluid Dynamic ◽  
Axial Compressor ◽  
Leading Edge ◽  
Navier Stokes ◽  
Test Case ◽  
Dynamic Simulations ◽  
Stall Margin ◽  
Casing Treatment

A proof of concept is provided by computational fluid dynamic simulations of a new recirculating type casing treatment. This treatment aims at extending the stable operating range of highly loaded axial compressors, so to improve the safety of sorties of high-speed, high-performance aircraft powered by high specific thrust engines. This casing treatment, featuring an axisymmetric recirculation channel, is evaluated on the NASA rotor 37 test case by steady and unsteady Reynolds Averaged Navier Stokes (RANS) simulations, using the realizable k-ε model. Flow blockage at the recirculation channel outlet was mitigated by chamfering the exit of the recirculation channel inner wall. The channel axial location from the rotor blade tip leading edge was optimized parametrically over the range −4.6% to 47.6% of the rotor tip axial chord c z . Locating the channel at 18.2% c z provided the best stall margin gain of approximately 5.5% compared to the untreated rotor. No rotor adiabatic efficiency was lost by the application of this casing treatment. The investigation into the flow structure with the recirculating channel gave a good insight into how the new casing treatment generates this benefit. The combination of stall margin gain at no rotor adiabatic efficiency loss makes this design attractive for applications to high-speed gas turbine engines.

Effect of J-Shaped Casing Treatment on Flow Stability and Performance of an Axial Compressor

2012 ◽  
Author(s):  
Ramjan R. Pathan ◽  
Quamber H. Nagpurwala ◽  
Ananthesha Bhat
Keyword(s):  
Incidence Angle ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Stability Margin ◽  
Tangential Component ◽  
Favourable Effect ◽  
Slight Reduction ◽  
Stall Margin ◽  
Casing Treatment ◽  
Transonic Compressor

Casing Treatment (CT) is one of the passive methods to increase the stability margin of the compress and hence that of the aircraft jet engines. In this paper, a novel J-shaped axial CT slot geometry is designed and numerically analysed for its effect on the performance of a single stage NACA transonic compressor. The predicted performance of the isolated rotor was validated by comparing with the published experimental results. The predicted efficiency of the baseline transonic rotor agreed well with experimental data, but the total pressure ratio was under predicted over the entire operating range. The J-shaped CT slots, with 100% axial coverage over the rotor tip chord, were able to extend the stall mass flow rate by almost 19.45% compared to the baseline rotor, accompanied with a slight reduction in rotor efficiency by 1.42%. The high pressure air entered the slots at rotor exit and flowed back through the slots and the plenum, and ejected at the rotor inlet to energise the low momentum end wall flow. The interaction of main inlet flow and the ejected flow having large tangential component of velocity, had favourable effect on the rotor incidence angle, and hence on rotor stall margin.

scholarly journals Simulation of Casing Treatments of a Transonic Compressor Stage

2008 ◽  
Vol 2008 ◽  
pp. 1-10 ◽  
Author(s):  
M. Hembera ◽  
H.-P. Kau ◽  
E. Johann
Keyword(s):  
Three Dimensional ◽  
Axial Compressor ◽  
Navier Stokes ◽  
Compressor Stage ◽  
Flow Solver ◽  
Stall Margin ◽  
Transonic Compressor ◽  
Flow Mechanisms ◽  
Multistage Compressor ◽  
Casing Treatments

This article presents the study of casing treatments on an axial compressor stage for improving stability and enhancing stall margin. So far, many simulations of casing treatments on single rotor or rotor-stator configurations were performed. But as the application of casing treatments in engines will be in a multistage compressor, in this study, the axial slots are applied to a typical transonic first stage of a high-pressure 4.5-stage compressor including an upstream IGV, rotor, and stator. The unsteady simulations are performed with a three-dimensional time accurate Favre-averaged Navier-stokes flow solver. In order to resolve all important flow mechanisms appearing through the use of casing treatments, a computational multiblock grid consisting of approximately 2.4 million nodes was used for the simulations. The configurations include axial slots in 4 different variations with an axial extension ranging into the blade passage of the IGV. Their shape is semicircular with no inclination in circumferential direction. The simulations proved the effectiveness of casing treatments with an upstream stator. However, the results also showed that the slots have to be carefully positioned relative to the stator location.

Numerical Investigation on the Effect of Bleed Port With Self-Recirculating Casing Treatment on the Stability of a 1.5-Stage Transonic Compressor

2019 ◽  
Author(s):  
Yiming Zhong ◽  
WuLi Chu ◽  
HaoGuang Zhang
Keyword(s):  
Pressure Ratio ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Stability Margin ◽  
Axial Position ◽  
Stable Operation ◽  
Stall Margin ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Compressor Efficiency

Abstract Compared to the traditional casing treatment, the self-recirculating casing treatment (SCT) can improve or not decrease the compressor efficiency while achieving the stall margin improvement. For the bleed port, the main design indicator is to reduce the flow loss caused by suction, while providing sufficient jet flow and jet pressure to the injector. In order to gain a better study of the bleed port stabilization mechanisms, the bleed configuration was parameterized with the bleed port inlet width and the bleed port axial position. Five kinds of recirculating casing treatments were applied to a 1.5-stage transonic axial compressor with the method of three-dimensional unsteady numerical simulation. Fifteen identical self-recirculating devices are uniformly mounted around the annulus. The numerical results show that the SCT can improve compressor total pressure ratio and stability, shift the stall margin towards lower mass flows. Furthermore, it has no impact on compressor efficiency. The optimal case presents that stability margin is improved by 6.7% employing 3.1% of the annulus mass flow. Expanding bleed port inlet width to an intermediate level can further enhance compressor stability, but excessive bleed port inlet width will reduce the stabilization effect. The optimal bleed port position is located in the blocked area of the low energy group at the top of the rotor. In the case of solid casing, stall inception was the tip blockage, which was mainly triggered by the interaction of the tip leakage vortex and passage shock. From radial distribution, the casing treatment predominantly affects the above 70% span. The reduction of tip reflux region by suction effect is the main reason for the extension of stable operation range. The SCT also has an obvious stability improvement in tip blockage stall, while delaying the occurrence of compressor stall.

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.

Effects of Circumferential Casing Grooves on the Performance of a Transonic Axial Compressor

2015 ◽  
Vol 32 (4) ◽  
Author(s):  
Minsuk Choi
Keyword(s):  
Axial Compressor ◽  
Leading Edge ◽  
Underlying Mechanism ◽  
Test Case ◽  
Reference Case ◽  
Stall Margin ◽  
Transonic Compressor ◽  
Stable Operating ◽  
Performance Curves ◽  
Downstream Flow

AbstractThe casing groove is a highly effective method for improving the stall margin with the least detrimental effect on the peak efficiency in an axial compressor. In this work, a single casing groove with different heights and positions was numerically tested to evaluate effects of each geometric parameter on the stall margin in a transonic compressor. Validation between the simulation and experiment was conducted with a smooth casing as a reference case, and the computed and experimental results were compared in terms of performance curves, downstream flow properties and Mach number contours. Subsequently, the performance curves for each test case with a single casing groove were obtained from the numerical results and compared with each other to determine the appropriate position and height of the groove for increasing the stall margin. A casing groove installed near the leading edge was found to be effective for expanding the stable operating range in a transonic compressor, giving about 3% point improvement in the stall margin at the cost of a small drop in efficiency at the design point. An attempt was also made to understand the underlying mechanism of the casing groove based on the analysis of the numerical flow data.

Optimization of Slots-Groove Coupled Casing Treatment for an Axial Transonic Compressor

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Guoming Zhu ◽  
Bo Yang
Keyword(s):  
Pareto Front ◽  
Leading Edge ◽  
Stall Margin ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Injection Flow ◽  
Optimization Stage ◽  
Stability Enhancement ◽  
Optimal Configurations ◽  
Casing Treatments

Abstract A multi-objective optimization of a coupled casing treatment (CCT) for an axial transonic compressor is performed in this study. The coupled casing treatment is the basis axial slots with a circumferential groove located at various positions along the slots. During the optimization stage, five important parameters to control the geometry are used as the optimal variables. The stall margin and the peak efficiency are selected as the optimal objectives. Non-dominated sorting genetic algorithm II coupled with radial basis function (RBF) approximation is used to search for Pareto-optimal solutions. Then, four optimal configurations are selected from Pareto-front for further analysis. As shown in the simulation results with and without the coupled casing treatments, the leakage flow is reenergized and the blocking region near the blade leading edge at rotor tip is decreased by the use of these structures under the low flowrate condition, which is the main reason for stability enhancement. Besides, a coupled casing treatment with the groove settled near the end of the basis slots have the potential to generate more injection flow and extend the operating range of compressor further.

Effect of Various Trench Designs on Axial Compressor Blade Tip Aerodynamics

2019 ◽  
Author(s):  
Ashwin Ashok ◽  
Patur Ananth Vijay Sidhartha ◽  
Shine Sivadasan
Keyword(s):  
Axial Compressor ◽  
Leading Edge ◽  
Suction Side ◽  
Horseshoe Vortex ◽  
Tip Clearance ◽  
Compressor Cascade ◽  
Tip Leakage Vortex ◽  
Stall Margin ◽  
Casing Treatment ◽  
Tip Leakage

Abstract Tip clearance of axial compressor blades allows leakage of the flow, generates significant losses and reduces the compressor efficiency. The present paper aims to discuss the axial compressor tip aerodynamics for various configurations of tip gap with trench. The various configurations are obtained by varying the clearance, trench depth, step geometry and casing contouring. In this paper the axial compressor aerodynamics for various configurations of tip gap with trench have been studied. The leakage flow structure, vorticity features and entropy generations are analyzed using RANS based CFD. The linear compressor cascade comprises of NACA 651810 blade with clearance height varied from 0.5% to 2% blade span. Trail of the tip leakage vortex and the horseshoe vortex on the blade suction side are clearly seen for the geometries with and without casing treatments near the stalling point. Since the trench side walls are similar to forward/backing steps, a step vortex is observed near the leading edge as well as trailing edge of the blade and is not seen for the geometry without the casing treatment. Even though the size of the tip leakage vortex seams to be reduces by providing a trench to the casing wall over the blade, the presence of additional vortices like the step vortex leads to comparatively higher flow losses. An increase in overall total pressure loss due to the application of casing treatment is observed. However an increase in stall margin for the geometries with casing is noted.

Experimental and Numerical Investigation of Effect of Center Offset Degree on Compressor Stability With Circumferential Grooved Casing Treatment

2016 ◽  
Author(s):  
HaoGuang Zhang ◽  
Feng Tan ◽  
YanHui Wu ◽  
WuLi Chu ◽  
Wei Wang ◽  
...  
Keyword(s):  
Axial Compressor ◽  
Leading Edge ◽  
Groove Depth ◽  
Tip Clearance ◽  
Central Difference ◽  
Stall Margin ◽  
Casing Treatment ◽  
Compressor Rotor ◽  
Stall Margin Improvement ◽  
Blade Tip

For compressor blade tip stall, one effective way of extending stable operating range is with the application of circumferential grooved casing treatment and its validity was proved by a lot of experimental and numerical investigations. The emphases of most circumferential grooved investigations are focused on the influence of groove depth and groove number on compressor stability, and there is few investigations dealt with the center offset degree of circumferential grooves casing treatment. Hence, an axial compressor rotor with casing treatment (CT) was investigated with experimental and numerical methods to explore the effect of center offset degree on compressor stability and performance. In the work reported here, The center offset degree is defined as the ratio of the central difference between rotor tip axial chord and CT to the axial chord length of rotor tip. When the center of CT is located within the upstream direction of the center of rotor tip axial chord, the value of center offset degree is positive. The experimental and numerical results show that stall margin improvement gained with CT is reduced as the value of center offset degree varies from 0 to 0.33 or −0.33, and the CT with −0.33 center offset degree achieves the lowest value of stall margin improvement at 53% and 73% design rotational speed. The detailed analysis of the flow-field in compressor tip indicates that there is not positive effect made by grooves on leading edge of rotor blade tip when the value of center offset degree is −0.33. As the mass flow of compressor reduces further, tip clearance leakage flow results in the outlet blockage due to the absence of the positive action of grooves near blade tip tail when the value of center offset degree is 0.33. Blockage does not appear in rotor tip passage owing to utilizing the function of all grooves with CT of 0 center offset degree.

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