导流块深度对抛物形凹面腔中激波反射聚焦的影响

Effects of Deflector Depth on Shock Wave Focusing in a Parabolic Cavity

为研究导流块深度对抛物形凹面腔内径向入射激波聚焦过程的影响,对马赫数为1.41的径向入射激波在导流块深度分别为0,5,10,15mm的凹面腔内反射聚焦过程进行了实验研究。结合高速CCD拍摄到的凹面腔中气流流场纹影照片和动态压力传感器测得的聚焦过程中流场的压力变化,对径向入射激波在凹面腔内的反射聚焦过程进行了描述。通过比较不同导流块深度下激波反射聚焦过程,发现随着导流块深度的加深,前导激波聚焦和反射激波聚焦的时间差会减小,使激波聚焦的强度增大,当导流块深度从0mm增加到15mm时,激波聚焦所致的峰值压力从0.39MPa增加到0.51MPa。但是,随着导流块深度的加深,压力增益下降,并使排气过程的难度加大,因此导流块深度为10mm左右时能取得较好的聚焦效果。

In order to obtain the effects of the deflector depth on the process of shock wave focusing in a parabolic cavity,experiments were carried out to investigate the radial incident shock focusing with Mach number1.41 in cavity where the depths of deflectors were 0,5,10,15 mm,respectively. Based on schlieren images of flow field in cavity captured by high-speed CCD camera and pressure histories recorded by dynamic pressure sensors,the behaviour of radial incident shock wave reflect and focus in a parabolic cavity was described. The shock wave focusing processes of different deflectors were compared. With the increase of the depth of deflectors,the time interval between leading shock focusing and reflect shock focusing decreases,which makes the strength of shock wave focusing increase. When the depth of deflectors increases from 0mm to 15 mm,the peak pressure caused by the shock wave focusing increases from 0.39 MPa to 0.51 MPa. However,with the increase of depth,the pressure gain reduces and exhaust process becomes much more difficult. Therefore,the depth of deflectors being about 10 mm can achieve better focusing effects.