Analysis of Aerodynamic Sound Source with Measurement of Static-Pressure Fluctuation.

Abstract

The objective of this investigation is to develop a method to detect the aerodynamic sound source in the wake of a circular cylinder at Reynolds number 4.0×104. We estimate the intensity of surface pressure which is related to vortex shedding in the wake of circular cylinder by using the coherent output power (COP) in terms of static-pressure and surface pressure on the circular cylinder. Then, we obtain vortices distribution which contribute dipole sound source on the cylinder by measuring COP at various positions in the wake of the circular cylinder. Moreover, we can calculate aerodynamic sound by using the Curle's equation with this estimated surface pressure. We also define the spatial distribution of aerodynamic sound source by means of this method. The result shows the aerodynamic sound generate near the formation region of Karman vortices, that is, X/D=1.5 to 2.0, Y/D=±0.4. Therefore, separated shear flow contributes strongly to the aerodynamic sound generation.