摘要
Research on the dynamic properties of a plasma sheath coupled with pitching motion of the vehicle has great significance in solving the problem of communication interruption in the process of vehicle reentry.This paper investigates the dynamic properties of the plasma sheath by using the simplified conventional Burnett(SCB)equations and the Navier-Stokes(NS)equations with the thermochemical non-equilibrium effect.The eleven-species chemical kinetic models are applied to the comparison and there is verification of a dynamic plasma sheath simulation for the first time.After the introduction of vehicle pitching motion,the dynamic results are more consistent with the experimental data than the simulated results when treating it as static state.The plasma sheath characteristic parameters show periodic properties,whose changing period is the same as the pitching motion period.However,because of different velocities of the pitching motion,phase shifts exist in different positions of the vehicle.The enhancement of the rarefied effect weakens the disturbance to the plasma sheath.This research reveals the distribution and regularities of the dynamic plasma sheath.It is significant in solving the ionization blackout problem and the design of the reentry vehicle,and provides reliable data for further research on the dynamic plasma sheath.
目的:通过对俯仰运动情况下的钝锥体等离子鞘套进行数值模拟,揭示动态等离子鞘套的分布规律,提高数据的可靠性,为进一步研究入射电磁波与动态等离子鞘套的相互作用机理提供有力依据,并为再入飞行器黑障问题的解决和再入飞行器设计提供参考。创新点:考虑热化学非平衡效应的简化常规Burnett(SCB)方程能够更准确地描述再入飞行器等离子鞘套的动态分布规律。方法:1.提出稀薄流域稳态与动态等离子鞘套数值模拟方法;2.对不同化学反应动力学模型和热力学模型进行数值比较和验证;3.引入俯仰运动后对再入飞行器等离子鞘套的动态特性进行数值模拟。结论:1.在稀薄流条件下SCB方程模拟得到的激波更厚,对等离子鞘套的刻画更为准确精细。2.7组元Gupta化学反应模型与Park双温模型的计算结果优于其他模型。3.引入俯仰运动后,飞行器不同位置的碰撞频率等关键参数与俯仰运动的周期存在相位差;同时增强稀薄效应将减弱俯仰运动对动态等离子鞘套的扰动。
