考虑阻力系数时变的下压段半解析时间预测方法

Semi-analytical encounter time estimation method in dive phase with time-varying drag coefficient

高超声速飞行器下压段飞行环境复杂、弹道参数变化剧烈、被动减速较快,传统解析预测采用的常值阻力系数假设不再适用。考虑攻角、马赫数影响,对阻力系数表达式进行拓展,基于解析理论对复杂弹道方程加以简化,得到以剩余射程为自变量的微分方程,通过数值积分快速求解弹道诸元,提升全弹道快速规划能力。典型弹道仿真表明,与传统常值假设相比,所提方法可将俯冲下压段的时间预报误差降低到1 s左右,同时不增加计算复杂度,实现滑翔飞行器俯冲飞行时间、速度、动压的精准、快速预报。

The constant drag coefficient hypothesis used in traditional analytical prediction is no longer applicable for hypersonic vehicle in the dive phase due to the complex flight environment,sharp change of trajectory parameters and fast passive deceleration.Considering the influence of angel of attack and Mach number,the expression of drag coefficient is extended,the complex ballistic equation is simplified based on analytical theory,and a differential equation with the remaining range as the independent variable is obtained.Therefore,the trajectory elements can be solved quickly by numerical integration to improve the capability of rapid planning of whole trajectory.Typical trajectory simulation shows that the time prediction error of the dive phase can be reduced to about 1 s compared with the traditional coefficient hypothesis.At the same time,it does not increase the computational complexity.It can realize the accurate and fast forecast of flight time,speed and dynamic pressure of glide vehicle.