| 冲击射流激波振荡与抑制 |
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| 作者姓名： | 李庠儒 刘年华 刘露菡 何枫 |
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| 作者单位： | 清华大学航天航空学院, 北京 100084 |
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| 基金项目： | 国家重点基础研究发展计划(973计划)(2012CB720100)。 |
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| 摘 要： | 欠膨胀冲击射流具有复杂的激波结构,并伴随产生高幅值的离散频率单音.通过高速摄像获取的纹影图像并结合噪声测量,对欠膨胀冲击射流激波振荡过程、剪切层不稳定波的模态和离散频率单音的产生进行了系列研究.给出了冲击距离为5倍喷嘴出口直径的复杂流动实验结果分析,射流剪切层不稳定波有对称和非对称两种模态,发现不同模态下的离散频率单音...
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| 关 键 词： | 欠膨胀 冲击射流 单音 激波振荡 降噪 |
| 收稿时间： | 2020-12-29 |
Suppression on Shock Oscillation of Impinging Jet |
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| Authors: | LI Xiang-ru LIU Nian-hua LIU Lu-han HE Feng |
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| Affiliation: | School of Aerospace Engineering, Tsinghua University, Beijing 100084, China |
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| Abstract: | Underexpanded impinging jets have complex shock structures and generate high-amplitude tones with discrete frequencies.Based on the schlieren images obtained by the high-speed camera and the results of noise measurements,the oscillations of shocks,the modes of instability waves in the jet shear layer and the generation of the discrete tones of underexpanded impinging jets were studied.In this paper,the experimental results of the impinging jet with an impact distance of 5 nozzle exit diameters were presented.It is found that there are two modes of the instability waves in the shear layer:symmetric and asymmetric modes.The sound source of the impinging tones at different modes is located at the instability flow structures after impinging on the plate.The feedback acoustic waves excite the shear layer at the nozzle lip and maintain the development of the instability waves.The oscillations of shocks are caused by the interactions between the shocks and the shear layer and are related to the characteristics of the instability modes.By weakening the disturbances of the feedback acoustic waves on the shear layer at the nozzle lip,the discrete tones are eliminated and the shock oscillations are suppressed. |
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| Keywords: | underexpanded jet impinging jet discrete tone shock oscillation noise reduction |
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