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Control and Application of a Locked in Phenomenon of a Jet Screech/Self-Exited-Vibration by using a Spherical Reflector.

使用球形反射器控制喷射/自激振动锁定现象的控制和应用。

基本信息

批准号：
15560201
负责人：
SETO Kunisato
金额：
$ 1.6万
依托单位：
SAGA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15560201/
关键词：
Spherical Reflector Jet Screech Shock Wave Self-Exited Vibration Resonance Noise Cancellation Sound Shielding 位相反転

项目摘要

One of the purposes of the present research is to clarify the generation mechanism of jet screech. The special issues are interaction between vortex disturbances and a shock wave and a resonance mechanism caused through instability of shear layer near to the exit of a nozzle.The next one is to control the jet screech by using a spherical reflector set at the nozzle exit that controls the location of an image noise source and cancels the jet screech.(1)In order to identify the coherence of sound waves, a laser beam sound detector has been designed and built up. Fundamental data of the performance have been obtained through current investigations.(2)Visual observation of the change in flow field by the attachment of a spherical reflector has been carried out by using a Schlieren system and a high speed video camera. It was found that the shock cell structure was kept up to downstream in case of the attachment of the spherical reflector. The reason is that cancellation of sound waves at t … More he nozzle exit quits exciting instability and stops generating disturbances. Hence the interaction between the disturbances and a shock wave becomes weak and the structure of the shock wave is not hampered.(3)The above mentioned observation has been carried out through a spherical reflector with a slit hole. The slit hole lowered the level of the noise cancellation but still held the effect.(4)Comparison of the sound cancellation effect between a spherical reflector and a flat plane reflector has been carried out.(5)Comparison of the sound cancellation effect between a spherical reflector and a parabola reflector has been carried out.(6)Sizing effect of a spherical reflector has been investigated by a variety of reflectors. It was confirmed that even a small sized spherical reflector could cancel a jet screech.(7)Noise reducing effect of spherical reflectors has been studied at various pressure ratios and it was shown that there is an appropriate radius of curvature corresponding to each pressure ratio.(8)In the above experiment, it was found that there was a special pressure ratio corresponding to any size of a spherical reflector where the noise reducing effect was highest.(9)Preparation for the measurement of magnitude of resistance (thrust loss) of a spherical reflector in flow has been done.(10)Preparation for the application of a spherical reflector to a duct silencer has been done. Less

本研究的目的之一是澄清射流尖叫的产生机理。特别是涡扰动与激波的相互作用和喷管出口附近剪切层不稳定引起的共振机制，以及在喷管出口处设置球面反射器，控制镜像噪声源的位置，消除射流啸叫，从而控制射流啸叫。(1)In为了识别声波的相干性，设计并制作了激光声探测器。通过目前的调查，获得了性能的基本数据。（2）利用纹影系统和高速摄像机对加装球面反射镜后的流场变化进行了目视观测。结果发现，在附加球形反射器的情况下，激波室结构保持在下游。原因是在t处声波的抵消 ...更多信息喷嘴出口停止激发不稳定性并停止产生扰动。因此，扰动和激波之间的相互作用变得很弱，并且激波的结构不会受到阻碍。（3）上述观测是通过带狭缝孔的球面反射镜进行的。狭缝孔降低了噪音消除的水平，但仍然保持效果。（4）对球面反射器和平面反射器的消声效果进行了比较。（5）对球面反射器和抛物面反射器的消声效果进行了比较。（6）研究了不同反射镜对球面反射镜尺寸的影响。结果表明，即使是一个小尺寸的球形反射器也可以消除喷流的尖叫声。（7）研究了球面反射器在不同压比下的降噪效果，结果表明，对于不同的压比，都存在一个合适的曲率半径。(8)In通过上述实验，发现存在对应于任何尺寸的球形反射器的特定压比，在该压比处降噪效果最高。（9）为球面反射器在流动中的阻力（推力损失）大小的测量做好了准备。（10）为球形反射器在管道消声器上的应用做好了准备。少