缩比发动机喷嘴热喷流噪声试验

为深入了解涡扇发动机喷流噪声特性，验证喷流噪声降噪方法，建立发动机喷流噪声数据库，在法国国家航天航空研究中心的CEPRA19声学风洞开展了缩比发动机喷嘴热喷流噪声试验测试工作。针对发动机热喷流模拟系统，设计加工了面积比（外涵喷嘴面积与内涵喷嘴面积之比）为5和7的两种喷嘴构型试验模型。通过减小高温区域单个零件长度尺寸和零件壁厚的方法，降低热膨胀对模型尺寸的影响。在声学风洞中完成了不同工况条件下两种面积比圆形喷嘴和锯齿形喷嘴的远场噪声特性测试。通过对远场测量噪声频谱进行分析，发现随着来流速度的增大喷流噪声会减小，采用锯齿形喷嘴设计在中低频喷流噪声水平降低，在高频噪声水平有所增加。

Test on hot jet noise of scaled engine nozzle

In order to understand the characteristics of turbofan engine jet noise, verify the method of reducing jet noise, and establish engine jet noise database, the hot jet noise test of scaled engine nozzle is carried out in CEPRA19 acoustic wind tunnel of the national aerospace and aeronautics research center of France. Aiming at the engine hot jet simulation system, two kinds of nozzle configurations, area ratio (the ratio of outer nozzle area to inner nozzle area) 5 and 7, are designed and manufactured. The effect of thermal expansion on the size of the model is reduced by reducing the length and thickness of a single part in the high temperature region. The far-field noise characteristics of circular nozzle and chevron nozzle with two area ratios under different working conditions are tested in an acoustic wind tunnel. The spectrum analysis of far-field measurement noise shows that the jet noise decreases with the increase of wind tunnel speed, for chevron nozzle the jet noise level decreases at middle-low frequency, and increases at high frequency.