Analysis of slightly jarring sound of a draft in automobile heating, ventilation, and air-conditioning unit(HVACunit)

摘要

A slightly jarring sound is caused by a breeze at a draft in a automobile Heating, ventilation, and Air-Conditioning unit(HVAC unit). We measured sound and wind velocity, and visualized wind stream using a high speed camera and white plasticpowder as a tracer. We certify the mechanism. A vortex is breaking out at the back of a door, continuously and at same interval because of the limited length between doorback to the counter edge(wall). So the sound is sharply peek sound. And we suggestsome simple measure of reduction its noise.