Sound Sources of Screech Tone Radiated from Circular Supersonic Jet Oscillating in the Helical Mode
Sound Sources of Screech Tone Radiated from Circular Supersonic Jet Oscillating in the Helical Mode
复制标题
螺旋振型圆形超音速射流辐射的刺耳音声源
DOI：
10.1260/147547202765275961
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发表时间：
2002
影响因子：
1
通讯作者：
R. Ishii
中科院分区：
文献类型：
--
作者：
Y. Umeda;R. Ishii
利用一系列瞬态纹影照片研究了螺旋振荡模式下尖声的产生机理。从照片中，观察到六个瞬逝声源作为沿射流轴沿着的突出点。这些声源沿着圆形轨道在垂直于射流轴线的平面内运动，并正好位于每个激波单元后缘的下游。移动声源的速度是超音速的，并且在移动声源后面产生的移动马赫锥形成尖叫音的螺旋形波前。通过对比纹影照片和运动马赫锥包络图，证实了绕喷流轴线运动马赫锥的存在。螺旋形旋涡结构似乎重叠在移动马赫锥的包络上。
The generation mechanism of the screech tone in the helical oscillation mode is investigated using a series of instantaneous schlieren photographs. From the photographs, six evanescent sound sources are observed as prominent points along the jet axis. These sound sources move along circular orbits in the planes perpendicular to the jet axis and just downstream of the rear edges of each shock cell. The speed of moving sound sources is supersonic and the moving Mach cones generated behind the moving sound sources form the helical-shaped wave front of the screech tone. Existence of the moving Mach cones about the jet axis was confirmed by comparing schlieren photographs and drawings of the envelopes of the moving Mach cones. The helical vortical structure appears to overlap on the envelopes of the moving Mach cones.