弹头激波诱导燃烧特性的数值模拟

Numerical Simulation of Projectile Shock-Induced Combustion

为了研究弹头激波诱导燃烧,基于有限体积的考虑化学反应的Navier-Stokes(N-S)方程,对预混氢气-空气化学恰当比时的燃烧流场进行了数值模拟.时间项基于2阶隐式LU-SGS格式,对流项基于Steger-Warming进行离散,化学反应源项采用对角化隐式处理.首先,研究了网格对燃烧爆轰流场结构的影响,并利用Lehr实验结果验证了计算方法的可靠性;其次,研究了弹头的飞行Mach数(Ma=4.18,5.11,6.46)、弹头直径(D=5,10,15 mm)对燃烧流场稳定性的影响.研究表明:计算网格对氢气-空气爆轰流场结构影响很大;弹头直径一定时,氢气-空气燃烧流场稳定性随着飞行Mach数的增大而增强;弹头飞行Mach数一定时,氢气-空气燃烧流场稳定性随着弹头直径减小而增强.

Numerical simulations were performed on premixed stoichiometric hydrogen-air flowfield around hypervelocity conical projectile based on finite-volume Navier-Stokes(N-S)equations considering chemical reaction to study shock-induced combustion with a variation in free-stream conditions and projectile diameter.The numerical methods were the second order time accurate LU-SGS scheme and Steger-Warming flux Jacobian splitting with chemical reaction source diagonalized implicitly.As a first step of validation procedure,simulation of Lehr′s experimental result was carried out to confirm the reliability of the method mentioned above,including the examination of the appropriateness of grid by grid refinement study.As a final step,the effects of the projectile flight Mach number(Ma=4.18,5.11,6.46)and the diameter(D=5,10,15 mm)on the stability of hydrogen-air combustion flow field were tested.Results show that,the grid refinement has great effect on hydrogen-air combustion flow structure,and the combustion field becomes more stable with increasing projectile Mach number and reducing diameter.