聚焦腔型面对环形激波聚焦起爆的影响

Effect of reflector shape on detonation initiation by toroidal shock wave focusing

为研究聚焦腔型面对起爆过程的影响和作用规律,以恰当比氢气/空气为反应物,对具有相同深度的半圆形、抛物线形和锥形3种型面聚焦腔诱导的起爆过程进行数值模拟研究。研究结果表明:与半圆形和抛物线形聚焦腔相比,锥形聚焦腔的诱导起爆距离分别缩短33.5%和12.1%。在3种型面聚焦腔内均发生了激波聚焦对撞和隔板反射造成的2次聚焦现象,其中,半圆形聚焦腔的一次聚焦压力最大,但是其回传压力损失也最大,这使得半圆形聚焦腔在一次聚焦后的火焰速度明显落后于其他结构。抛物线形和锥形聚焦腔内波系演变过程中的腔壁反射激波具有加强二次聚焦的作用,腔壁反射激波越强聚焦诱导的起爆越早。

The detonation initiation process induced by reflectors with semi-circular,parabolic,or conical shape and the same depth has been numerically investigated to study the mechanism and influence of reflector shape on the detonation initiation by toroidal shock wave focusing,with a stoichiometric hydrogen/air mixture as the reactant.The result indicates that compared with the semi-circular and parabolic reflectors,the distance of detonation initiation in the conical one reduced by 33.5%and 12.1%,respectively.Double shock wave focus generation occurred in the reflectors:the first one was caused by the collision of compressed wave and the other one by the reflection of the diaphragm.The first focusing pressure of the semi-circular reflector was the strongest,but its return pressure loss was also the largest.Such phenomenon resulted in the significantly smaller flame speed in the semi-circular reflector compared with that in the others after the first focusing.The shock wave reflected by the wall of parabolic and conical reflectors can enhance the second focusing.The stronger the shock wave is,the earlier the detonation initiation occurs.