An investigation of the dynamic stalling characteristics of rotating axial-flow compressor blades

Abstract

A multichannel FM telemetry system was employed to measure the dynamic response of compressor rotor blade surface pressure profiles to changes in upstream conditions. Data taken while the experimental compressor was operating with a distortion screen upstream of the rotor was utilized to develop a transfer function to describe the dynamic response of the rotor blade row. The transfer function was developed by considering the dynamic total pressure loss distribution around the rotor to be a response function driven by a quasi-steady total pressure loss distribution as a forcing function. Fourier transforms of both the dynamic and the quasi-steady distributions were calculated. The quotient obtained by dividing the Fourier transform of the response function by the Fourier transform of the forcing function was the desired transfer function.

This experimentally-determined transfer function was then used in a new semi-actuator disc model to predict the dynamic response of the experimental compressor. The basis of the model is a mathematical representation of the flow fields upstream and downstream of a compressor rotor. The compressor rotor is represented in the model by a semi-actuator disc.

The results of the investigation show that the physical mechanisms which control the onset and propagation velocity of a rotating stall in a single-stage compressor can be modeled with the use of a transfer function in a semi-actuator disc model of the compressor. The transfer function represents the dynamic characteristics of the compressor rotor row as an amplitude ratio and a phase shift of the Fourier frequency components of the total pressure loss distribution. This transfer function representation of the dynamic characteristics of the blade row provides important advantages over previous techniques.