Directional Suppression of Noise from a High-Speed Jet
Directional Suppression of Noise from a High-Speed Jet
复制标题
高速喷射噪声的定向抑制
DOI：
10.2514/2.1345
复制
发表时间：
2001
期刊：
影响因子：
2.5
通讯作者：
M. Debiasi
中科院分区：
文献类型：
--
作者：
D. Papamoschou;M. Debiasi
实验证明了使用非对称平行二次流的高速射流噪声的定向抑制。二次流衰减了声远场下半球的马赫波辐射，使向上传播的马赫波保持不变。内流马赫数为1.5，700 m/s，外流马赫数为1.0，360 m/s的偏心喷管布置产生的噪音降低比同心布置或完全混合的等效射流产生的噪音降低好上级。峰值感知噪声的角度从后象限向横向方向移动。偏心布置的优点是由于其相对于同心射流的势核较短。实验还揭示了未经处理的喷流发出强烈的裂纹，这是由马赫波的非线性引起的噪声分量。次级气流抑制裂纹。
Experiments demonstrate directional suppression of noise from a high-speed jet using an asymmetric parallel secondary stream. The secondary stream attenuates Mach wave radiation in the lower hemisphere of the acoustic far eeld, leaving unaltered the upward-propagated Mach waves. An eccentric nozzle arrangement with a Mach 1.5, 700-m/s inner stream and a Mach 1.0, 360-m/s outer stream produces noise reduction superior to that from concentric arrangements or from the fully mixed equivalent jet. The angle of peak perceived noise shifts from the aft quadrant to the lateral direction. The beneet of the eccentric arrangement is attributed to its shorter potential core relative to a concentric jet. The experiments also reveal emission of strong crackle from the untreated jet, a noise component arising from the nonlinearity of Mach waves. The secondary eow suppresses crackle.