Breakdown of Tip Leakage Vortices in Compressors at Flow Conditions Close to Stall

Schlechtriem, Stefan; Lötzerich, Michael

doi:10.1115/97-gt-041

Cited by 81 publications

(44 citation statements)

References 10 publications

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“…The first one is the Leading Edge Blade Tip Leakage Vortex (LEBTLV), which induces a large loss region in the middle of the passage. Many researchers [7][8][9] hypothesize that the breakdown of the LEBTLV is a probable triggering mechanism of the stall. Although the vortex breakdown has yet to happen in Figure 2, it is evident that LEBTLV is critical in the flow.…”

Section: Critical Flow Structures At Stall With Smooth Wall Configuramentioning

confidence: 99%

An analysis of the Circumferential Grooves Casing Treatment for transonic compressor flow

Huang

Chen

Shi

et al. 2010

Sci. China Phys. Mech. Astron.

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The stall mechanism of the NASA Rotor 37 is investigated through the analysis of the critical flow structures near the stall under the transonic condition. The performance of the rotor with Circumferential Grooves Casing Treatment (CGCT) is also studied based on the Reynolds-Averaging Navier-Stokes approach. The study finds that stall margin improvement can be achieved without significant penalty on the efficiency for the two CGCT configurations applied. The effects of circumferential grooves on the critical flow structures are studied through the analysis of the tip leakage mass and momentum transport that further reveal the CGCT mechanism. transonic compressor, Circumferential Grooves Casing Treatment, stall margin, leakage mass and momentum transportation analysisCasing treatment as a passive flow control method to extend the stable operating range for a tip critical rotor has been used for years. While it can give rise to improved stall margin, there is usually an associated efficiency penalty. This is due to the lack of good knowledge on the mechanism of casing treatment, and the design often largely depends on ad hoc experience. Circumferential Grooves Casing Treatment (CGCT) is simple and effective in stall margin improvement. Much research has been done in this area. Rabe & Hah [1] studied the effects of the CGCT on the flow field of a transonic compressor both experimentally and computationally. Those effects include the change of incidence of the main flow near the blade pressure side, tangential velocity effect, segmentation of blade tip leakage vortex (BTLV) and the in-and outflow effects. Wilke and Kau [2] conducted a numerical study on CGCT on a HPC front stage. The circumferential grooves were reported to suppress the extension of the BTLV and improve the stall margin. Shabbir & Adamcyzk [3] studied the physical mechanism of the CGCT with an analysis on the axial momentum budget for a low speed rotor. Müller et al. [4] studied the effects of CGCT on an axial single stage transonic compressor both experimentally and numerically with four configurations of CGCT. The configuration with deep grooves and large coverage showed the best results on the stall margin improvement in both design and off design speed.However, the mechanism of CGCT is still not fully understood. This paper mainly focuses on the effects of CGCT on some critical flow structures related to the stall process. The leakage mass and momentum transport are analyzed for a better understanding of the mechanisms of CGCT. Although the stall is a highly unsteady process, the steady RANS method captures the stall related critical flow structures well. Thus the RANS method is believed suitable for a relative study on the casing treatment.This paper first discusses the critical flow structures at the near stall condition of smooth wall (SW) configuration. Then the rotor performance with CGCT is presented and compared with SW case results. CGCT effects on the critical flow structures are discussed to explain the per-

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Section: Critical Flow Structures At Stall With Smooth Wall Configuramentioning

confidence: 99%

An analysis of the Circumferential Grooves Casing Treatment for transonic compressor flow

Huang

Chen

Shi

et al. 2010

Sci. China Phys. Mech. Astron.

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“…And injection can shift the position of tip leakage vortex towards downstream and thus delay the inception of stall. It has been known that tip clearance flow plays an important role in the initiation of rotating stall in axial compressors [16][17][18]. In the case of micro injection, with such tiny amount of injected air the stable compressor characteristic should not be influenced and thus could keep its shape unchanged.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigations of micro air injection to control rotating stall

et al. 2007

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Steady discrete micro air injection at the tip region in front of the first compressor rotor has been proved to be an effective method to delay the inception of rotating stall in a low speed axial compressor. Considering the practical application a new type of micro injector was designed and described in this paper, which was imbedded in the casing and could be moved along the chord. In order to verify its feasibility to other cases, such as high subsonic axial compressor or centrifugal compressor, some other cases have been studied. Experimental results of the same low speed axial compressor showed that the new injector could possess many other advantages besides successfully stabilizing the compressor. Experiments performed on a high subsonic axial compressor confirmed the effectiveness of micro air injection when the relative velocity at the blade tip is high subsonic. Meanwhile in order to explore its feasibility in centrifugal compressor, a similar micro injector was designed and tested on a low speed centrifugal compressor with vaned diffuser. The injected mass flow was a bit larger than that used in axial compressors and the results showed micro injection could also delay the onset of rotating stall in the centrifugal compressor.

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“…Various studies (for example, see references [9] to [12]) have proposed tip leakage vortex (TLV) 'breakdown' as a possible cause of stall initiation. Hoying et al [13] suggested that the spike type of rotating disturbance might be explained by the behaviour, the TLV moving upstream of rotor as the incidence angle increased.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of the unsteady behaviour of tip clearance flow and its possible link to stall inception

Chu

et al. 2009

Proceedings of the Institution of Mechanical Engineers, Part A:

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Three-dimensional unsteady calculations were performed to explore the unsteady nature of tip clearance flow and its possible linking with the spike stall inception. It was found that the interaction of the broken-down leakage vortex with the tip clearance flow formed another distinctive vortex, denoted as the tip separation vortex. It formed below the rotor blade tip section and propagated diagonally inward. This vortex propagated across the rotor passage from the pressure side to the suction side with its vortex core filled with low-energy fluid. The spike emergence during stall inception included the breakdown of the tip leakage vortex and the formation and movement of the tip separation vortex.

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Breakdown of Tip Leakage Vortices in Compressors at Flow Conditions Close to Stall

Cited by 81 publications

References 10 publications

An analysis of the Circumferential Grooves Casing Treatment for transonic compressor flow

An analysis of the Circumferential Grooves Casing Treatment for transonic compressor flow

Experimental investigations of micro air injection to control rotating stall

Numerical investigation of the unsteady behaviour of tip clearance flow and its possible link to stall inception

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