Experimental Investigation of Discrete Frequency Noise Generated by Unsteady Blade Forces

Abstract

A critical experiment was designed and carried out to study discrete frequency noise generation from an axial flow compressor row. The experiments were carried out in a small-scale Freon loop. Two arrays of rods were introduced upstream of a single compressor rotor so as to cause acoustic modes oriented approximately normal and parallel to the blade force. R. Mani’s analysis of the coupling of unsteady forces to acoustic modes was applied to these experimental results. Good agreement was obtained.