耦合时间精度对模拟飞行器自由运动特性的影响

Influence of Coupling Time Accuracy on the Simulation of Aircraft Free Movement

将亚迭代技术引入流体动力学和刚体动力学方程的耦合求解,获得细长三角翼极限环运动的规律.探讨耦合时间精度对飞行器非定常运动特性的影响,细长三角冀的大迎角自由滚运动最终形成极限环振荡的周期性自维持运动,不同攻角自由滚振幅阶跃式的变化特点较好地吻合了自由滚试验的规律.对于多系统耦合问题,亚迭代耦合求解(耦合时间精度为二阶)对物理时间步长的依赖性不明显;而存在一阶时间滞后的解耦推进方法的数值结果强烈地依赖于物理时间步长选取,稍大的时间步长将导致非物理的数值结果.

With a sub-iterative technique for fluld dynamic equations and rigid-body dynamic equations, a coupling numerical method is proposed to explore the unsteady movement characteristics of aero-crafts and the effect of coupling time accuracy. It is shown that the motion finally becomes a serf-maintained stable limit cycle oscillation. The amplitude with an increasing incidence angle shows a jump, which is quite close to the experimental result. The coupled numerical result with the secand-order lime accuracy depends hardly on the physical time step for this multi-system coupling. On the contrary, the uncoupled numerical result with one step time lag depends obviously on the physical time step selected. A longer time step results in unreal numerical results.