1515 Fundamental Study on the Mechanism of Noise Generation in the Sirocco-Fan for Automobile Air Conditioner

Abstract

The final purpose of this study is to clarify the relation between the static pressure fluctuation between fan blades and the sound noise emitted to the outside of the fan. For this purpose, first of all, a new micro probe for the measurement of the static pressure fluctuation has been developed. The measurement of the static pressure fluctuation between the blades has been performed, and the intensity of sound source was quantified from the second derivative of phase averaged static pressure fluctuation signal (Ribner 1962). It is shown that the intensity of sound source becomes largest when the blade approaches to the nose. The difference between the cooling mode and the heating mode are also investigated. It is found that the sound source for cooling mode shows the larger value than that for heating as a whole.