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阐明喷气尖叫的发电机理。特殊问题是涡流灾难与冲击波之间的互动，以及通过剪切层接近喷嘴出口而引起的共振机制。下一个是通过使用球形反射器设置在控制喷嘴的球形反射器设置的情况下控制喷气机尖叫声，以控制图像噪声源的位置，并降低了射击的位置。（2）通过使用Schlieren系统和高速摄像机进行了球形反射器的附着，通过接触球形反射器的附着来对性能的基本数据进行了视觉观察。发现在球形反射器附着的情况下，冲击电池结构保持在下游。原因是在t上取消声波……更多的鼻子出口罕见的场合令人兴奋的不稳定，并停止造成灾难。因此，灾难与冲击波之间的相互作用变得薄弱，冲击波的结构并没有受到阻碍。（3）上述观察结果是通过带有狭缝孔的球形反射器进行的。狭缝孔降低了取消噪声的水平，但仍保持效果。（4）对球形反射器和平面反射器之间的声音取消效果进行了比较。（5）比较球形反射器与抛物线反射器之间的声音取消效果的比较。（6）各种反射器已经研究了球形反射器的尺寸。已经证实，即使是一个小尺寸的球形反射器也可以取消喷气尖叫声。（7）已经以各种压力比研究了球形反射器的降噪作用，并且表明表明与每个压力比相对应的适当的曲率半径。（8）在上述实验中，有一个特殊的压力比相对于任何噪声，而噪声是噪声的最高效应。已经完成了球形反射器在流动中的电阻（推力损失）的测量。（10）已准备了将球形反射器应用于导管消音器的准备。