'Middle East Technical University, Faculty of Architecture'
Abstract
This thesis study is focused on experimentally investigating pump noise at design and off-design operations and its relations with pressure fluctuations. Small size pumps are placed in a semi-anechoic chamber and operated at various system conditions and various rotational pump speeds. Pump operational data, noise data and time dependent pressure data are recorded. Fast Fourier Transform spectra of noise and pressure data are compared. Coherence spectrum between sound pressure level and hydraulic pressures are obtained. Data processing, Fast Fourier Transform and cross correlation are conducted with specific software Soundbook SAMURAI. The experiments have indicated that system characteristics or pump size do not have any influence on the noise of pump. On the other hand, pump characteristics are found to be distinguishable by means of peak frequencies on the sound spectra which are proportional to blade passing frequency. Results of cross correlations also show that, pump outlet pressure is a more significant source of noise than pump inlet pressure.M.S. - Master of Scienc