Effects of Tip Clearance on Stall Inception in a Multistage Compressor

Abstract

Rotor tip clearance height and the associated tip leakage flow have a significant effect on the performance and stability of compressors. Existing studies considering tip clearance effects on stability have been primarily limited to low-speed compressors, and many of these evaluated single-stage machines, which may not adequately represent stall trends for enginescale compressors. Furthermore, test campaigns for engine-scale compressors cannot provide instrumentation accessibility required for detailed stage performance and stall investigations. Using results collected from a three-stage intermediate-speed axial compressor with appreciable density rise, this study addresses these needs. In this paper, three rotor tip clearances are tested, ranging from 1.5% to 4% span (1% to 3% chord). Previous studies have primarily shown a transition from short-length-scale spikes to longlength-scale modes as the clearance is increased, whereas the present study shows the opposite: a transition from modes to spikes with increased tip clearance. As a result, these data emphasize that a definitive trend does not exist between the stall inception mechanism and increasing tip clearance. Instead, the clearance effects alter stage matching with speed and change the stall inception mechanism. These results also elicit future research by preliminarily suggesting that stall inception mechanisms may be predictable from steady performance measurements collected in the stalling stage.

Compressor Stall Warning Using Nonlinear Feature Extraction Algorithms

“…Instrumentation details can be found in Ref. 22. In this study, the pressure signal from a single transducer instrumented upstream of rotor 1 was used for the purpose of stall warning, as indicated in Fig.…”

“…A detailed analysis of the tip clearance effects on stall inception for this machine can be found in Ref. 22. A few key findings can be summarized: (1) for this compressor, stage 1 is always the limiting stage, which was indicated by the consistent rollover in stage 1 static-to-static characteristics and also supported by the unsteady pressure measurements; (2) stall cells develop in stage 1, further extends to stages 2 and 3, and eventually cause the whole machine to go into stall; (3) the compressor showed a change in prestall signature with changes in rotor tip clearance.…”

Influence of vaned diffuser on the potential effect of volute and stall inception of centrifugal compressor

“…According to the unsteady pressure signal in the compressor flow field, two types of stall inception were confirmed: modal type and spike type. [1][2][3][4] In some compressors, both stall inception types even appeared simultaneously 5,6 and transformed from the modal disturbance to the spike-type stall inception during the stall formation process. 7 Geometric variations, such as the axial distance of compressor rows and stagger angle 8 and the circumferential inflow distortion 9 altered the type of stall inception of the compressor.…”

Transient characteristics of internal flow fields of mixed-flow pump with different tip clearances under stall condition

“…In case of compressors, Inoue et al, 16 Weichert and Day 17 and Pullan et al 18 have found that the tornado-like vortex generated at the leading edge of the blade is the main cause for the stall vortex development and its propagation and the presence of tornado-like vortex may be attributed to the spillage of TLF in front of the leading edge of the blade. 19 Thus, the intensity of TLF may determine the time when critical stall point may occur. In our previous study, 20 it was shown that the intensity of TLF has a strong correlation with the tip clearance size in the mixed-flow pump, and therefore it is worthwhile to investigate the internal flow fields of the mixed-flow pump under different tip clearances.…”