Experiments on the Dominant Noise Sources in Centrifugal Turbomachinery Operating On and Off-Design

Abstract : The goal of this research was to develop an understanding of the strongest noise sources present in centrifugal turbomachinery with an aim of providing information toward the design of quieter machines. Previous investigations at Penn State revealed two noise production mechanisms. Additional research was initiated to enhance the understanding of the effect of geometric and flow modifications on noise production. Quantification of noise source types was also desired to determine the kind of interaction present at the impeller trailing edges. This, in turn, leads to information on methods to reduce noise. More specifically, the objectives of the research were to assess the influence on the fluid dynamics and associated aeroacoustics of the centrifugal turbomachine of the following: (1) off-design operation, (2) inlet flow distortion, and (3) trailing edge geometry. (MM)