来流边界层效应下斜坡诱导的斜爆轰波

摘要

The behavior of reacting shock wave in supersonic premixed flow with the effect of incoming boundary layer is investigated experimentally. A supersonic premixed flow at a Mach number of 3 encounters a ramp, and an oblique detonation wave (ODW) is produced. Four ramp angles (θ) are designed from 36◦ to 45◦ (interval of 3 degree) and the equivalence ratio (Φ) can be varied. At a lower equivalence ratio, the ODW cannot be initiated and instead the shock-induced combustion (SIC) comes into being. It is discovered that the overall flow field presents more significant unsteadiness for SIC than for inert shock wave because the separation region is greatly enlarged for SIC due to heat release by chemical reactions in the separation region. As for the ODW, it is prone to propagating upstream after initiated for current experimental conditions. For 39◦ ramp, the separation region of boundary layer is relatively small, and the ODW presents an abrupt pattern for which a transverse wave exists. However, larger separation region for 42◦ramp and its unsteadiness make the transverse wave intermittently appear. For 45◦ ramp, the even larger separation region makes the transverse wave thoroughly disappear and the ODW presents a smooth pattern.%以超声速预混气中的斜爆轰波为研究对象，对其在来流边界层效应下的特性进行了实验研究。在马赫数为3的超声速预混风洞中，通过斜坡诱导产生了斜爆轰波。当来流的当量比较低时，预混气中产生的是化学反应锋面与激波面非耦合的激波诱导燃烧现象。此时边界层分离区中的化学反应放热将使分离区尺度显著增大，流场非定常性显著增强，激波位置剧烈振荡。当来流的当量比较高时，预混气将产生斜爆轰波。此时边界层分离区会影响到斜爆轰波起爆时的形态。在小尺度分离区下，斜爆轰波起爆时呈突跃结构(有横波)；在中等尺度分离区下，流场固有的非定常性使斜爆轰波呈间歇突跃结构；在大尺度分离区下，斜爆轰波起爆则呈完全的平滑结构(无横波)。