瞬态泄压过程中二次燃烧对底排装置尾部流场影响的数值分析

Numerical Analysis of the Effect of Post-combustion on the Tail Flow Field of Base Bleed Equipment in Transient Depressurization Process

为了研究瞬态泄压过程中二次燃烧对底排弹尾部加能的影响,建立了底排装置瞬态泄压过程中尾部化学非平衡流的数学物理模型。采用对流迎风矢通量分裂格式(AUSM+)的改进格式、切应力运输湍流模型SST k-ω模型和8组分12步反应的H2─CO反应动力学机理,运用统一算法的思路编程求解二维轴对称Navier-Stokes方程,对尾部流场进行数值模拟,得到泄压过程中底排燃烧室压力随时间的变化规律,模拟结果和文献实验结果基本吻合。在此基础上对泄压过程中有无二次燃烧两种条件下的尾部流场进行数值预测,分析了泄压过程中底排装置尾部流场特征参数随时间的变化规律。结果表明,泄压过程前期,二次燃烧对尾部流场影响较小。而在泄压中后期,二次燃烧对尾部流场影响较大,此时,尾部流场特征参数更快趋于稳定,且二次燃烧使尾部流场温度提高,加能效果显著,底压增大,底排弹底阻明显减小,减阻率比不含二次燃烧的减阻率提高了75%。

To investigate the effect of post-combustion on the energy addition at tail of base bleed projectile in the transient depressurization process,a mathematical and physical model of the chemical non-equilibrium flow at tail in the transient depressurization process for base bleed equipment was established. Two-dimensional axial symmetric Navier-Stokes equations were solved by idea programming of uniform algorithm using the improved format of convective upwind vector flux splitting format (AUSM+),the shear stress transport turbulence model SST k-ω and the H2─CO reaction kinetic mechanism of 12-step reaction of 8 components. The numerical simulation of tail flow field was performed,the change rule of pressure in base bleed combustion chamber in the transient depressurization process with time was obtained. The simulated results were basically in agreement with the experimental ones in the literature. Base this basis,the tail flow field under the condition of with and without post-com - bustion in the transient depressurization process were numerically predicted,and the change rule of characteristic parameters for the tail flow field of base bleed equipment with time in the transient depressurization process were analyzed. The results show that the post-combustion has a little effect on the tail flow field in the early stage of transient depressurization process,while in the middle and late stage,the post-combustion has a great effect on the tail flow field. At this time,the characteristic parameters of tail flow field more quickly tend to be stable,and the post-combustion makes the temperature of tail flow field increase and the energy addition effect remarkable,the bottom pressure increase,the bottom drag of base bleed projectile decrease significantly and the drag reduction rate increases by 75% compared with that without post-combustion.