Performance and noise evaluation of an axial flow fan design with various blade tip shapes

Abstract

Detailed tests were conducted on standard shape axial flow fans as well as blades with tip treatment. The object of the tests was to determine the optimum tip configuration. To evaluate the effect of changes in trip clearance, the tests were performed with a blade to shroud clearance of 0.5 and 0.75 in. All other system and environmental factors were held constant. The test facility was designed to standards based on a recently developed induct sound power measuring system which includes a measuring section for fan performance measurements, a microphone system consisting of a microphone with attached sampling tube developed to handle crossmodes and suppress flow noise, and a nearly anechoic termination to deal with the problem of end reflections. The measured data compares aerodynamic performance, specific sound characteristics, radial distribution of velocity components, and the noise spectra at various operating conditions. The results indicate that fan tip design has a significant influence on fan performance and fan noise.