前缘射流对空腔噪声抑制效果的试验研究

目的通过在开式空腔前缘增加矩形口射流、九孔射流和九斜孔射流,探究三种射流方式对空腔自激振荡噪声的抑制效果。方法通过风洞试验对亚、跨声速(Ma=0.3、0.45、0.6)下基于前缘射流的空腔噪声抑制方法开展研究,在空腔指定位置安装传声器,获取不同工况下空腔内的噪声信息,综合对比三种射流方式下空腔峰值频率、空腔底部及后壁声压级分布、总声压级分布及不同测点处的频率曲线特征,评估三种前缘射流方式对空腔噪声的控制效果。结果在来流速度Ma=0.3时,三种射流方式对空腔峰值频率处的声压级均有一定抑制效果,但由于前缘射流的引入导致空腔前端底部噪声总声压级提高;在来流速度Ma=0.45时,三种射流方式对空腔峰值频率处的声压级及宽频噪声均有显著抑制效果;在来流速度Ma=0.6时,除矩形口射流对空腔噪声有明显的抑制作用,其他两种射流方式使得空腔内噪声水平增强。结论在空腔前缘引入射流在一定来流速度下能够实现空腔峰值频率处噪声及宽频噪声的有效降低,前缘射流对空腔噪声的抑制效果随射流方式的不同而存在较大差异。

Experiment on the Effect of Front-edge Jet on Cavity Noise Suppression

The work aims to investigate the suppression effects of three jet methods on cavity self-excited oscillation noise by adding rectangular mouth jet, nine-hole jet and nine-slope-hole jet. The method of cavity noise suppression based on front-edge jet at subsonic and transonic speed (Ma=0.3, 0.45, 0.6) was studied by wind tunnel test. The microphone was installed at the designated position of the cavity to obtain the noise information in the cavity under different working conditions. The peak frequency of the cavity, the sound pressure level distribution at the bottom and back wall of the cavity, the total sound pressure level distribution and the frequency curve characteristics at different measuring points were comprehensively compared under the three jet methods, and the suppression effects of the three front-edge jet methods on the cavity noise were evaluated. When the flow velocity was Ma=0.3, the three jet methods had certain suppression effects on the sound pressure level at the peak frequency of the cavity, but the introduction of the front-edge jet led to an increase in the total sound pressure level of the noise at the bottom of the front-bottom of the cavity. When the flow velocity was Ma=0.45, the three jet methods had significant suppression effects on the sound pressure level and broadband noise at the peak frequency of the cavity. When the flow velocity was Ma=0.6, the noise level in the cavity was enhanced by the other two jet methods except the rectangular mouth jet. Introducing jet at the front-edge of the cavity can effectively reduce the noise at the peak frequency of the cavity and broadband noise at a certain flow velocity, and the suppression effect of front-edge jet on cavity noise varies greatly with different jet methods.