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

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).

Co-simulation approach for computational aero-acoustic modeling: Investigating wind-induced noise within two-way radio microphone ports cavity

“…Hairudin et al [18] performed a wind tunnel test to investigate the effect of cavity position on noise levels, demonstrating that the farthest position resulted in minimal wind noise levels. In another study, Hairudin et al [19] used flow visualization method to examine the flow structure produced under different cavity length-to-depth (L/D) ratios of microphone ports through wind tunnel testing. The results indicated that microphone ports with a small L/D ratio produced a single vortex shedding, while those with larger L/D ratios exhibited multiple vortices.…”