Influence of self-circulating casing treatment with double-bleed ports structure on compressor performance

2020 ◽  
Vol 234 (11) ◽  
pp. 1743-1756
Author(s):  
Song Yan ◽  
WuLi Chu
Keyword(s):  
The Self ◽  
Suction Surface ◽  
Stall Margin ◽  
Casing Treatment ◽  
Flow Capacity ◽  
Stall Margin Improvement ◽  
Blade Tip ◽  
Design Speed ◽  
The Stability ◽  
Experimental Values

Casing treatment is an effective way to improve the stable working margin of the compressor and plays an important role in ensuring the stable and safe work of the compressor. On the premise that the numerical results are in agreement with the experimental values, the paper study on a new type of the self-circulating casing treatment with double-bleed ports structure was carried out on the NASA rotor 37 by numerical simulation. It is found that compared with the self-circulating casing treatment with single-bleed port structure, the self-circulating casing treatment with double-bleed ports structure is more favorable for improving the stall margin of the rotor, and the improvement of the stall margin obtained at the rotor design speed is as high as 9.57%. Compared with the other two self-circulating casing treatments with single-bleed port structure, the improvement of the stall margin is increased by 37.90 and 49.53%, respectively. The self-circulating casing treatment with double-bleed ports structure has a significant effect on the enhancing stability, but at the same time, it causes a greater efficiency loss, which reduces the design point efficiency of the rotor by 0.34%. Through detailed analysis of the flow field, it is found that the self-circulating casing treatment improves the flow capacity of the blade tip region, weakens the blockage degree of the blade tip region, and reduces the blade tip load, thereby improving the stall margin of rotor. Compared with the self-circulating casing treatment with single-bleed port structure, the self-circulating casing treatment with double-bleed ports structure is more advantageous for delaying the flow separation of the suction surface, delaying the occurrence of the blade tip stall to make the stability of rotor more favorable, and obtained stall margin improvement is the greatest.

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 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.

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.

Numerical Investigation on Slot Casing Treatment in a Transonic Axial Compressor Stage: Part 1 — Casing Treatment Design

2016 ◽  
Author(s):  
Mingmin Zhu ◽  
Xiaoqing Qiang ◽  
Jinfang Teng
Keyword(s):  
Axial Compressor ◽  
Leakage Flow ◽  
Compressor Stage ◽  
Tip Leakage Flow ◽  
Suction Surface ◽  
Stall Margin ◽  
Rotating Speed ◽  
Casing Treatment ◽  
Tip Leakage ◽  
Stall Margin Improvement

Slot-type casing treatment generally has a great potential of enhancing the operating range for tip-critical compressor rotors, however, with remarkable efficiency drop. Part I of this two-part paper was committed to develop a slot configuration with desired stall margin improvement and minimized efficiency loss. Steady simulation was carried out in a 1.5 transonic axial compressor stage at part design rotating speed. At this rotating speed this compressor stage operated at a subsonic condition and showed a rather narrow operating range, which needed to be improved badly. Flow fields analysis at peak efficiency and near stall point showed that the development of tip leakage vortex and resulting blockage near casing resulted in numerical stall. Three kinds of skewed slots with same rotor exposure and casing porosity were designed according to the tip flow field and some empirical strategies. Among three configurations, arc-curved skewed slot showed minimum peak efficiency drop with considerable stall margin improvement. Then rotor exposure and casing porosity were varied based on the original arc-curved skewed slot, with a special interest in detecting their impact on the compressor stability and overall efficiency. Result showed that smaller rotor exposure and casing porosity leaded to less efficiency drop. But meanwhile, effectiveness of improving compressor stability was weakened. The relation between efficiency drop and stall margin improvement fell on a smooth continuous curve throughout all slots configurations, indicating that the detrimental effect of casing treatment on compressor was inevitable. Flow analysis was carried out for cases of smooth casing and three arc-curved configurations at smooth casing near stall condition. The strength of suction/injection, tip leakage flow behavior and removal of blockage near casing were detailed examined. Larger rotor tip exposure and slots number contributed to stronger injection flow. The loss generated within the mixing process of injection flow with main flow and leakage flow is the largest source of entropy increase. Further loss mechanisms were interpreted at eight axial cuts, which were taken through the blade row and slots to show the increase in entropy near tip region. Entropy distributions manifested that loss generations with smooth casing were primarily ascribed to low-momentum tip leakage flow/vortex and suction surface separation at leading edge. CU0 slot, the arc-curved slots with 50% rotor tip exposure, was capable of suppressing the suction surface separation loss. Meanwhile, accelerated tip leakage flow brought about additional loss near casing and pressure surface. Upstream high entropy flow would be absorbed into the rear portion of slots repeatedly, resulting in further loss.

Stall Margin Improvement by Use of Casing Treatments

2013 ◽  
Author(s):  
Christian T. Pixberg ◽  
Heinz-Peter Schiffer ◽  
M. H. Ross ◽  
J. D. Cameron ◽  
S. C. Morris
Keyword(s):  
Tip Clearance ◽  
Stall Margin ◽  
Tip Clearance Flow ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Clearance Flow ◽  
Beneficial Impact ◽  
Stall Margin Improvement ◽  
Blade Tip ◽  
Casing Treatments

The beneficial impact of casing treatments on the stall margin of tip-critical compressors has been proven many times. However, there is still no simple and general method to predict their actual effectiveness. The present work considers the axial velocity deficit that is generally observed at the blade tip. This so called tip-blockage is caused by the tip clearance flow. That is investigated for different configurations of the transonic compressor test facilities in Darmstadt and Notre Dame and the results are presented in this paper. Similar circumferential groove casing treatments were applied to different single-stage and 1.5-stage compressors. They all had a tip critical behavior in common, but exhibited different design philosophies. The effectiveness of similar casing treatments on different stages was observed. A new method for calculating tip-blockage is introduced based on compressor performance and the results of a through-flow tool. A direct link between blockage growth and stall margin improvement was found for circumferential grooves casing treatments. Additionally, the results of an axial slot casing treatment are taken into account.

Effects of Rotating Inlet Distortion on Compressor Stability With Stall Precursor-Suppressed Casing Treatment

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Xu Dong ◽  
Dakun Sun ◽  
Fanyu Li ◽  
Donghai Jin ◽  
Xingmin Gui ◽  
...  
Keyword(s):  
Stability Problem ◽  
Axial Fan ◽  
Stall Margin ◽  
Casing Treatment ◽  
Inlet Distortion ◽  
Large Size ◽  
Flow Disturbances ◽  
Stall Margin Improvement ◽  
The Stability ◽  
Stall Precursor

This paper conducts an experimental research of rotating inlet distortion on a low-speed large size test compressor with emphasis on the stability problem of axial fan/compressors, and the stall margin enhancement with a kind of stall precursor-suppressed (SPS) casing treatment. Some results on compressor stall margin and prestall behavior under the restriction of rotating inlet distortion are presented. The experimental results show that whether the inlet distortion is co-rotating or counter-rotating, the SPS casing treatment can still improve the stall margin without leading to additional efficiency loss caused by such configuration. The experiment results also show that the mechanism of the stall margin improvement with such casing treatment is associated with delaying the nonlinear development of the stall precursor waves and weakening the unsteady flow disturbances in a compression system.

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 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.

Sign in / Sign up

Export Citation Format

Share Document