Further Investigation on Acoustic Stall-Warning Approach in Compressors

Abstract

A further investigation of an acoustic theory-based stall-warning approach is presented in this paper, which contains the basis of this approach and an application on a low-speed compressor (LSC) with a stabilization system. In the present work, this stall-warning approach is first explained through a numerical simulation in which the periodicity of pressure signals is analyzed, and then application experiments of this approach are actualized on a LSC with a stall precursor-suppressed (SPS) casing treatment (CT) as a stabilization system. For this stall-warning approach, a parameter named Rc is calculated through pressure signals of compressor to evaluate the periodicity of pressure signal, and statistical estimates are implemented on Rc so that the probabilities for Rc less than a threshold Rcth can be used as a criterion for stall warning. The numerical and experimental results both show that the signal resolution is determined by the sensor position, the prestall signal amplitude decreases rapidly with the increase of the distance between sensor and blades. Results also show that the probability increases significantly when the operating point is nearing the stall boundary. And at the same operating point, the probability value of Rc will decrease when the SPS CT is engaged. Through this stall-warning approach, a stabilization system based on SPS CT can be activated when the stall margin needs to be extended.