Stall Margin Improvement by Casing Treatment—Its Mechanism and Effectiveness

1977 ◽  
Vol 99 (1) ◽  
pp. 121-133 ◽  
Author(s):  
H. Takata ◽  
Y. Tsukuda
Keyword(s):  
Axial Flow ◽  
Stall Margin ◽  
Low Speed ◽  
Casing Treatment ◽  
Blade Row ◽  
Stall Margin Improvement ◽  
Flow Through ◽  
Compressor Performance ◽  
Axial Flow Compressors

Experiments on the effect of casing treatment were carried out using low-speed axial-flow compressors. Results on the overall compressor performance and on the flow through the blade row as well as the flow within the treatment slots are presented. Then, based on the experiments, a possible mechanism of the stall margin improvement is suggested.

scholarly journals Axial Flow Compressor Stability Enhancement: Circumferential T-Shape Grooves Performance Investigation

Aerospace ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 12
Author(s):  
Marco Porro ◽  
Richard Jefferson-Loveday ◽  
Ernesto Benini
Keyword(s):  
Vortex Breakdown ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Suction Side ◽  
Treatment Technique ◽  
Tip Leakage Flow ◽  
Stall Inception ◽  
Stall Margin ◽  
Casing Treatment ◽  
Stall Margin Improvement

This work focuses its attention on possibilities to enhance the stability of an axial compressor using a casing treatment technique. Circumferential grooves machined into the case are considered and their performances evaluated using three-dimensional steady state computational simulations. The effects of rectangular and new T-shape grooves on NASA Rotor 37 performances are investigated, resolving in detail the flow field near the blade tip in order to understand the stall inception delay mechanism produced by the casing treatment. First, a validation of the computational model was carried out analysing a smooth wall case without grooves. The comparisons of the total pressure ratio, total temperature ratio and adiabatic efficiency profiles with experimental data highlighted the accuracy and validity of the model. Then, the results for a rectangular groove chosen as the baseline case demonstrated that the groove interacts with the tip leakage flow, weakening the vortex breakdown and reducing the separation at the blade suction side. These effects delay stall inception, improving compressor stability. New T-shape grooves were designed keeping the volume as a constant parameter and their performances were evaluated in terms of stall margin improvement and efficiency variation. All the configurations showed a common efficiency loss near the peak condition and some of them revealed a stall margin improvement with respect to the baseline. Due to their reduced depth, these new configurations are interesting because they enable the use of a thinner light-weight compressor case as is desirable in aerospace applications.

scholarly journals Effects of Endwall Suction and Blowing on Compressor Stability Enhancement

1989 ◽  
Author(s):  
N. K. W. Lee ◽  
E. M. Greitzer
Keyword(s):  
Flow Injection ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Primary Objective ◽  
Stall Margin ◽  
Casing Treatment ◽  
Blade Row ◽  
Stall Margin Improvement ◽  
Stability Enhancement ◽  
Suction And Blowing

An experimental investigation was carried out to examine the effects on stall margin of flow injection into, and flow removal out of, the endwall region of an axial compressor blade row. A primary objective of the investigation was clarification of the mechanism by which casing treatment (which involves both removal and injection) suppresses stall in turbomachines. To simulate the relative motion between blade and treatment, the injection and removal took place through a slotted hub rotating beneath a cantilevered stator row. Overall performance data and detailed (time-averaged) flowfield measurements were obtained. Flow injection and removal both increased the stalling pressure rise, but neither was as effective as the wall treatment. Removal of high blockage flow is thus not the sole reason for the observed stall margin improvement in casing or hub treatment, as injection can also contribute significantly to stall suppression. The results also indicate that the increase in stall pressure rise with injection is linked to the streamwise momentum of the injected flow, and it is suggested that this should be the focus of further studies.

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.

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.

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.

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.

Mechanism of affecting the performance and internal flow field of an axial flow subsonic compressor with self-recirculation casing treatment

2020 ◽  
pp. 095441002094267
Author(s):  
Hao G Zhang ◽  
Fei Y Dong ◽  
Wei Wang ◽  
Wu L Chu ◽  
Song Yan
Keyword(s):  
Flow Field ◽  
Axial Flow ◽  
Internal Flow ◽  
Leading Edge ◽  
Tip Clearance ◽  
Stall Margin ◽  
Casing Treatment ◽  
Leakage Flows ◽  
Blade Tip ◽  
Compressor Performance

This investigation aims to understand the mechanisms of affecting the axial flow compressor performance and internal flow field with the application of self-recirculation casing treatment. Besides, the potentiality of further enhancing the compressor performance and stability by optimizing the geometric structure of self-recirculation casing treatment is discussed in detail. The results show that self-recirculation casing treatment generates about 7.06, 7.89% stall margin improvements in the experiment and full-annulus unsteady calculation, respectively. Moreover, the compressor total pressure and isentropic efficiency are improved among most of operating points, and the experimental and calculated compressor peak efficiencies are increased by 0.7% and 0.6%, respectively. The comparisons between baseline shroud and self-recirculation casing treatment show that the flow conditions of the compressor rotor inlet upstream are improved well with self-recirculation casing treatment, and the degree of the pressure enhancement in the blade top passage for self-recirculation casing treatment is higher than that for baseline. Further, self-recirculation casing treatment can restrain the leading edge-spilled flows made by the blade tip clearance leakage flows and weaken the blade tip passage blockage. Hence, the flow loss near the rotor top passage is reduced after the application of self-recirculation casing treatment. The rotor performance and stability for self-recirculation casing treatment are greater than those for baseline. The flow-field analyses also indicate that the adverse effects caused by the clearance leakage flows of the blades tip rear are greater than those made by the clearance leakage flows of the blades leading edge. When one injecting part of self-recirculation casing treatment is aligned with the inlet of one blade tip passage, the flow-field quality in the passage is not the best among all the passages between two adjacent injecting parts of self-recirculation casing treatment. Further, the flow-field analyses also indicate that the effect of the relative position between the blade and self-recirculation casing treatment on the flows in the self-recirculation casing treatment may be ignored during the optimization of the recirculating loop configuration.

Mechanism investigation of enhancing the stability of an axial flow rotor by blade angle slots

2019 ◽  
Vol 233 (13) ◽  
pp. 4750-4764 ◽  
Author(s):  
Haoguang Zhang ◽  
Wenhao Liu ◽  
Enhao Wang ◽  
Yanhui Wu ◽  
Weidong Yao
Keyword(s):  
Axial Flow ◽  
Maximum Efficiency ◽  
Smooth Wall ◽  
Blade Angle ◽  
Stall Margin ◽  
Casing Treatment ◽  
Flow Losses ◽  
Stable Operating ◽  
Stall Margin Improvement ◽  
The Stability

This paper seeks to reveal the mechanisms of enhancing the stability of a subsonic axial flow rotor by applying blade angle slots casing treatment (BSCT). When blade angle slots are applied, there is about 9% stall margin improvement for the experiment and about 8% stall margin improvement for the calculation, but the decrease in the rotor maximum efficiency is about 11% for the experiment and the calculation. The compared results between smooth wall and blade angle slots indicate that the backflow in the rotor top passage is weakened by the injected and sucked flows formed inside the slots of BSCT. Moreover, the injected flows inside the slots interfere with the flows in the rotor passage upstream, and this interference leads to large flow losses. Therefore, the rotor efficiency for blade angle slots is much lower than that for smooth wall. To confirm that the structural optimization of blade angle slots can effectively improve the compressor stability with small efficiency losses, optimized blade angle slots casing treatment (BSCT1) was designed according to the past experience of slot casing treatment. The calculated result shows that the optimized blade angle slots generate about 59% stall margin improvement, and the compressor maximum efficiency with the optimized blade angle slots is about 0.05% more than that for smooth wall. The flow field analyses show that the strong sucked flows formed inside the slots for BSCT1 can prevent the backflow, which exists in the rotor top passage for BSCT, from appearing. In addition, the level of interference of the flows in the rotor passage upstream for BSCT1 is much lower than that for BSCT, and the corresponding losses with BSCT1 become lower. Therefore, the rotor with BSCT1 has a larger stable operating range and better efficiencies than that with BSCT.

Effects of Endwall Suction and Blowing on Compressor Stability Enhancement

1990 ◽  
Vol 112 (1) ◽  
pp. 133-144 ◽  
Author(s):  
N. K. W. Lee ◽  
E. M. Greitzer
Keyword(s):  
Flow Injection ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Primary Objective ◽  
Stall Margin ◽  
Casing Treatment ◽  
Blade Row ◽  
Stall Margin Improvement ◽  
Stability Enhancement ◽  
Suction And Blowing

An experimental investigation was carried out to examine the effects on stall margin of flow injection into, and flow removal out of, the endwall region of an axial compressor blade row. A primary objective of the investigation was to clarify the mechanism by which casing treatment (which involves both removal and injection) suppresses stall in turbomachines. To simulate the relative motion between blade and treatment, the injection and removal took place through a slotted hub rotating beneath a cantilevered stator row. Overall performance data and detailed (time-averaged) flowfield measurements were obtained. Flow injection and removal both increased the stalling pressure rise, but neither was as effective as the wall treatment. Removal of high-blockage flow is thus not the sole reason for the observed stall margin improvement in casing or hub treatment; injection can also contribute significantly to stall suppression. The results indicate that the increase in stall pressure rise achieved with injection is linked to the streamwise momentum of the injected flow, and it is suggested that this should be the focus of further studies.

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