A Qualitative Study of the Wind Noise Cavity Inside of a Two Way Radio

Abstract

Abstract The cavity inside microphone of two-way radio can induced noise when involved in outdoor and windy condition. An investigation was performed in Viwika wind tunnel involving a flow visualizations techniques to clarify the flow noise behavior generated by the wind, particularly within the cavity. A smoke wire test was conducted using a cavity model at varying aspect ratio (L/D) between 0.7 and 3 in angle of attack of 0º with Reynolds number of 7831. A two-dimensional Computational Fluid Dynamic (CFD) models based on k-Epsilon turbulence model were conducted to validate the flow visualization result. The results revealed that the deep cavity with an aspect ratio (L/D) of 0.7 produced a single clockwise vortical flow structure and the aspect ratio (L/D) of 3 show the complex flow structure which two recirculation flow vortices were produced inside the cavity. The flow behavior in the CFD simulation was similar to the smoke test. It is shown the flow behaviour inside cavities was control by the aspect ratio (L/D).