锯齿喷口参数对喷流噪声特性的影响

喷流噪声是主要的飞机噪声源之一,影响飞机的适航噪声水平和舱内乘坐舒适性。针对单涵冷喷流噪声,通过试验研究V形喷口几何参数,锯齿个数、锯齿长度、锯齿的嵌入角度等对噪声抑制效果的影响。研究发现:压比1.52和1.69时,增加锯齿的个数,可以有效地提高降噪水平;压比1.89时,增加锯齿个数增大了高频噪声的水平;增加锯齿的长度,并不能改善降噪效果。增加锯齿的嵌入角度,可以有效地降低中低频噪声,但高频噪声显著增加;在压比1.69和1.89时,锯齿喷口的噪声谱线中有幅值较高的驼峰,可能是锯齿诱导产生了高频激波造成的。

Effect of Chevrons Parametric on Acoustics Characteristics of Jet

Jet noise is one of aircraft major noise, which has a big impact on the aircraft noise certification and cabin comfortable. Experimental investigations have been carried out in this paper to assess the importance of chevron parameters, such as chevron count, chevron length and chevron penetration. Results indicate that chevron count provided benefits to noise reduction under NPR(nozzle pressure ratio)=1.89 and NPR=1.69, but high frequency noise increased at NPR=1.89. Increasing chevron length with the same chevron count had a little effect on noise reduction. Chevron penetration increased high frequency noise and reduced low frequency noise well. Chevron nozzle induced high frequency shock that radiated intense noise, when the NPR=1.69 and 1.89.