弯管内爆轰波传播的流场显示和数值模拟

采用激光纹影系统拍摄了爆轰波在不同位置的流场照片. 用二阶附加半隐的龙格- 库塔法和五阶WENO格式 分别离散欧拉方程时间和空间导数项，用基元反应来描述爆轰化学反应过程，获得了压力、 温度、典型组元质量分数分布及数值胞格结构和爆轰波平均速度. 结果表明：受壁面稀疏波 和压缩波影响，爆轰波阵面发生畸变. 但由于弯管曲率半径较大，未出现爆轰波熄灭. 靠近 凹壁面的激波强度大于凸壁面侧，且凹壁面侧的反应区宽度较凸壁面侧要窄. 弯管出口处的 三波点数目较入口处减少，爆轰波衰减. 在出口直段，受扰动的爆轰波可恢复为自持爆轰波. 爆轰波流场、胞格结构、平均爆轰波速度的计算和实验结果定性一致.

Schlieren visualization and numerical simulation on gaseous detonation propagation through a bend tube

Gaseous detonation propagation through a semi-circle bend tube was experimentally and numerically investigated. The laser schlieren system was employed to obtain the images of detonation front at the different position. The 2nd additive semi-implicit Runge-Kutta method and 5th order WENO scheme were respectively used to discretize the time and space terms of reactive Euler equations. Detailed chemical reaction model was utilized to describe the processes of detonation chemical reactions. The contours of pressure, temperature, OH mass fraction, numerical cellular pattern and average detonation speed were obtained. Experimental and numerical results show that, influenced by the rarefaction waves and compressio.n waves, the detonation front is distorted. Due to the shallow curvature of the bend tube, the detonation front is not so seriously distorted and there is no evidence of detonation failure. The leading shock along the concave wall is much stronger than that along the convex wall. The reaction zone along the convex wall is also wider than that along the concave wall. The triple-point number decreases in the process of detonation propagation through the bend tube, and therefore the detonation wave is degenerated. However, it can be recuperated to self-sustaining cellular detonation at the exit section. The computed detonation flow field, cellular pattern and average speed are qualitatively consistent with those from the experiments.