开口式汽车气动声学风洞的低频颤振现象

Buffeting Phenomenon of Openjet Automotive Aeroacoustic Wind Tunnel

摘要:

通过上海地面交通工具风洞中心的1/15模型风洞，按破坏喷口涡流(噪声源)、收集口反馈以及驻室结构三种极限状况，对风洞中的低频颤振现象开展试验研究.通过对比不同状况下声压频谱、压力脉动系数及低频颤振现象主要频率随风速的迁移，更加认清产生低频颤振的机理.对于本模型风洞来讲，产生低频颤振的耦合因素主要是：喷口剪切层涡流激发了驻室Helmholtz共振；喷口剪切层涡流频率与全回路声学模态发生耦合；涡流剪切层及其收集口尖劈反馈共振，构成气流自激系统.

Abstract:

Based on a 1/15 model wind tunnel of the Shanghai Automotive Wind Tunnel Center,an experimental study is made of the buffeting phenomenon of openjet wind tunnel on the basis of three limiting configurations in charge of the vortex of nozzle (source of noise),feedback of collector and the structure of plenum,respectively.A comparative study of the spectrum of sound pressure，coefficient of pressure pulsation and movements of frequency that shifted with wind speed and where buffeting occurs,reveals the coupling factors more clearly.For the wind tunnel model,the coupling factors of buffeting are as follows:vortex of nozzle excites the helmholtz resonation of plenum and is coupled with the acoustic modal of full circuit,and the selfexcited system,is resonated by the vortex of nozzle and the feedback of collector.