侧向脉冲喷流瞬态干扰流场探讨

Observation of transient interaction of lateral impulse jet

关键词:  步进发动机  非定常流  瞬态喷流效应+  喷流干扰  流动分布

Key words:  Stepping motor  Unsteady flow  Transient jet-interaction~+  Jet interference  Flow distribution

摘要:

当姿态控制发动机工作时间很短时, 喷流干扰产生的非定常气动特性就显得非常重要。为了研究脉冲发动机起动到关闭过程中引起的非定常气动特性对导弹控制效应的影响, 采用了二阶时间精度的LU隐式时间推进格式和双时间计算技术, 数值求解了飞行马赫数M∞=5, 迎角α=0°情况下, 拦截导弹姿态控制脉冲发动机喷流的瞬态过程和所产生的非定常气动特性。以0 001ms间隔观察了导弹表面在喷流出口附近非定常干扰流动分离区的发展过程。给出了详细的喷流瞬态干扰流场结构, 以及喷流瞬态干扰区随时间改变的流场细节特性。研究表明: 喷流前的高压区和喷流后的低压区对非定常效应非常敏感。并且, 当喷流已完全关闭时刻还存在喷流羽流的残余干扰量。

Abstract:

The side thruster is a highly responsive means for attitude control of missiles. As the jet pulse time shortens, however, the effect of flow transients becomes increasingly important to fluid dynamics of jet interaction. In order to study the control effects due to the transient nature of jet startup and shutdown, transient jet-interaction(TJI) phenomena and unsteady aerodynamic were analyzed by computational method using LU-SSOR implicit time-marching second order accurate scheme and double time technology at M_∞=5,α=0°.The development of the flow separated section around the vicinity of side jet exit was observed at the every 0.001 ms. Results show that at the moment of the shutoff of the thruster there is residual influence in the jet flow, which shows the delay effect of the unsteady field. And especially, they will translate into fairly large effects on normal force and pitching moment that allows us to explain why the transient jet/hypersonic-flow interaction enhances the effect of the jet reaction force in the jet startup and shutdown.