T型管内爆轰流场演变的数值模拟

Numerical Study on Evolution of Flow Field of Detonation in T-tube

基于带化学反应的二维Euler方程,对2H_2/O_2/Ar系统在T型管内的传播进行了研究。用二阶附加半隐的RungeKutta法和五阶WENO格式分别离散欧拉方程的时间和空间导数项,采用9组分48步基元反应简化模型描述爆轰波分别在静止系统和流动系统中传播过程,得到了爆轰流场纹影、压力及数值胞格结构。结果表明:爆轰波进入水平管的爆轰波左右两侧发生衍射,导致爆轰波熄灭。诱导激波与上壁面碰撞反射诱导左右两侧爆轰波重新起爆,横向爆轰波阵面的小扰动进入马赫波,强度逐渐放大,最终波阵面上出现胞格结构。由于下壁面拐点附近出现爆轰"死区",下壁面爆轰波的产生比上壁面稍晚。

Based on two-dimensional Euler equations associated with chemical reactions,gaseous detonation of 2H2/ O2/ Ar mixture propagation through a T-tube has been investigated numerically. The second-order additive semi-implicit Runge-Kutta methods and the fifth-order weighted essentially non-oscillatory（ WENO） scheme were used to discretize the time term and the convection term,respectively. 9 species and 48 elementary reactions model was applied to describe processes of detonation chemical reactions. The schlieren image,contours of pressure as well as numerical cellular patterns were obtained. Results show that,detonation fails on both the left and right side due to the detonation diffracting from confinement through an abrupt area expansion. With the development of shock wave,the detonation happens to re-initiate due to the reflection of incident shock from the upper wall. Some small perturbations which originate from transverse detonation wave front propagate into Mach wave. The small perturbations get stronger and stronger,and the front of Mach wave appears cellular structure,ultimately. Since ＂dead zone＂of cellular structure locates near corner of the T-sharped tube,the re-initiation of detonation happens along back wall later than front wall.