超声速弹丸诱导爆轰波的无网格数值模拟

Numerical Simulation of Denotation Wave Induced

关键词:  无网格方  HLLC格式  有限速率反应模型  爆轰波

Key words:  Gridless method  HLLC scheme  Finite rate chemical model  Detonation wave

摘要:

为研究锥角对超声速弹丸诱导爆轰波形态的影响，发展了耦合有限速率化学反应模型的最小二乘显式无网格算法，其流体动力学采用含化学反应源项的多组分Euler方程建模，对流项和时间项分别采用多组分HLLC(Harten-Lax-van Leer-Contact)格式和四阶Runge-Kutta法计算。对尖劈诱导斜爆轰以及激波诱导燃烧流场进行了模拟，验证了算法的有效性。最后对等当量比甲烷/空气预混气体中，不同锥角弹丸诱导爆轰波流场进行了模拟，云图同实验阴影照片吻合较好，结果表明当锥角处于70°～100°时，易形成驻定斜爆轰波；锥角较小不利于可燃混合气体的点燃，仅能形成驻定斜激波；过大的锥角将导致爆轰波的脱体。

Abstract:

The gridless method coupled with finite rate chemical model was developed to study the effects of conical angle on the structure of denotation shock induced by supersonic projectile. The fluid dynamics was modeled by multi-component Euler equations with chemical sources. The numerical flux was calculated by the multi-component HLLC (Harten-Lax-van Leer-Contact) scheme. A four-stage Runge-Kutta algorithm was employed to advance the equations in time. The flows of wedge-induced oblique denotation and shock-induced combustion were simulated to validate in respect of accuracy firstly. The denotation wave phenomena induced by supersonic projectile with different conical angles in the stoichiometric methane/air mixture were simulated subsequently. The contours agree well with the experimental shadowgraphs，and the results show that the oblique detonation wave is prone to be standing with conical angle at the range of 70°～100°，when the conical angle is not large enough ，it does not avail to ignite combustible mixture，only oblique shock is found in the flow field，contrarily，the denotation wave would be detached.