Single and Multiple Circumferential Casing Groove for Stall Margin Improvement in a Transonic Axial Compressor

Abstract The stability limit of a tip-stalling axial compressor is sensitive to the magnitude of the near casing blockage. In transonic compressors, the presence of the passage shock could be a major cause for the blockage. Identification and elimination of this blockage could be key to improving the stability limit of the compressor. In this paper, using numerical simulation, the near casing blockage within the transonic rotor, NASA Rotor 37, is quantified using a blockage parameter. For a smooth casing, the blockage at conditions near stall has been found to be maximum at about 20% of the tip axial chord downstream of the tip leading edge. This maximum blockage location is found to be consistent with the location of the passage shock-tip leakage vortex interaction. A datum single casing groove design that minimises the peak blockage is found through an optimisation approach. The stall margin improvement of the datum casing groove is about 0.6% with negligible efficiency penalty. Furthermore, the location of the casing groove is varied upstream and downstream of the datum location. It is shown that the stability limit of the compressor is best improved when the blockage is reduced upstream of the peak blockage location. The paper also discusses the prospects of a multi-groove casing configuration.

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SINGLE AND MULTIPLE CIRCUMFERENTIAL CASING GROOVE FOR STALL MARGIN IMPROVEMENT IN A TRANSONIC AXIAL COMPRESSOR

Journal of Turbomachinery ◽

10.1115/1.4050444 ◽

2021 ◽

pp. 1-22

Author(s):

Ahmad Fikri Bin Mustaffa ◽

Vasudevan Kanjirakkad

Keyword(s):

Axial Compressor ◽

Stability Limit ◽

Leading Edge ◽

Vortex Interaction ◽

Stall Margin ◽

Tip Leakage ◽

Stall Margin Improvement ◽

Transonic Axial Compressor ◽

The Stability ◽

Transonic Rotor

Abstract The stability limit of a tip-stalling axial compressor is sensitive to the magnitude of the near casing blockage. In transonic compressors, the presence of the passage shock could be a major cause for the blockage. Identification and elimination of this blockage could be key to improving the stability limit of the compressor. In this paper, using numerical simulation, the near casing blockage within the transonic rotor, NASA Rotor 37, is quantified using a blockage parameter. For a smooth casing, the blockage at conditions near stall has been found to be maximum at about 20% of the tip axial chord downstream of the tip leading edge. This maximum blockage location is found to be consistent with the location of the passage shock-tip leakage vortex interaction. A datum single casing groove design that minimises the peak blockage is found through an optimisation approach. The stall margin improvement of the datum casing groove is about 0.6% with negligible efficiency penalty. Furthermore, the location of the casing groove is varied upstream and downstream of the datum location. It is shown that the stability limit of the compressor is best improved when the blockage is reduced upstream of the peak blockage location. The paper also discusses the prospects of a multi-groove casing configuration.

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Effects of Endwall Suction and Blowing on Compressor Stability Enhancement

Volume 1: Turbomachinery ◽

10.1115/89-gt-64 ◽

1989 ◽

Cited By ~ 2

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.

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Effect of forward swept leading edge on a transonic axial compressor rotor stall margin

Modelling and Computation in Engineering ◽

10.1201/b10025-6 ◽

2010 ◽

pp. 27-30

Keyword(s):

Axial Compressor ◽

Leading Edge ◽

Stall Margin ◽

Compressor Rotor ◽

Transonic Axial Compressor

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Effect of Rotor Tip Casing Treatment on the Performance and Stall Margin of a Transonic Axial Compressor Stage

International Journal of Engineering Research and ◽

10.17577/ijertv6is100037 ◽

2017 ◽

Vol V6 (10) ◽

Author(s):

Prof. Tukaram P. H. ◽

Prof. Subbaramaiah S. V ◽

Subbaramu S. ◽

Keyword(s):

Axial Compressor ◽

Compressor Stage ◽

Stall Margin ◽

Casing Treatment ◽

Transonic Axial Compressor

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Low speed axial compressor stall margin improvement by unsteady plasma actuation

Journal of Thermal Science ◽

10.1007/s11630-014-0684-8 ◽

2014 ◽

Vol 23 (2) ◽

pp. 114-119 ◽

Cited By ~ 3

Author(s):

Gang Li ◽

Yanji Xu ◽

Lingyuan Yang ◽

Wei Du ◽

Junqiang Zhu ◽

...

Keyword(s):

Axial Compressor ◽

Stall Margin ◽

Low Speed ◽

Plasma Actuation ◽

Stall Margin Improvement

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

Volume 2A: Turbomachinery ◽

10.1115/gt2016-56757 ◽

2016 ◽

Cited By ~ 1

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

Volume 1: Advances in Aerospace Technology ◽

10.1115/imece2016-65260 ◽

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.

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