转捩位置对全动舵面热气动弹性的影响

高超声速附面层的转捩预测一直是流体力学研究中的难点,转捩前后物面的摩擦系数和传热系数会发生改变,转捩位置的不同会影响到飞行器表面热环境,进而使得飞行器的气动弹性特性发生显著变化.鉴于高超声速附面层转捩预测的不确定性,本文分析了转捩位置对高超声速全动舵面热气动弹性的影响.首先分别用层流模型和湍流模型求解N-S方程,得到气动热环境,并对气动热进行参数化;然后在不同转捩位置情况下构造出不同转捩位置的热分布模型,基于此种温度分布,结合热应力和材料属性的影响分析结构的热模态,将结构模态插值到气动网格上,采用基于CFD的当地流活塞理论进行气动弹性分析.以M=6,H=15 km的某舵面为对象进行计算,结果表明:(1)随着转捩位置向后缘移动,结构频率上升,结构颤振速度呈增大趋势,转捩位置的变化能够带来颤振临界速度最大6%的变化量;(2)当转捩位置位于舵轴附近时,结构的颤振特性变化剧烈.通过刚度特性的分解和分析发现,导致颤振特性变化的主要因素在于舵轴的刚度特性变化,舵轴的影响量占整个结构刚度特性变化量的80%以上.

THE EFFECT OF TRANSITON LOCATION ON AEROTHERMOELASTICITY OF A HYPERSONIC ALL-MOVABLE CENTROL SURFACE

The transition prediction of hypersonic boundary layer has been a difficulty in fluid dynamics. The friction coefficient and heat-transfer coefficient could be changed because of transition. The location of transition has an effect on thermal environment around the aircraft surface, which accounts for marked changes of Aeroelastic characteristics further. Considering the uncertainly of transition prediction of hypersonic boundary layer, this paper has analyzed the effects of transition location to aerothermodynamics of hypersonic all-movable control surface. First of all, the thermal environment around the control surface is obtained by solving the N-S (Navier-Stocks) equation using the model of laminar and turbulent flow respectively. In the next place, a parameterized model considering the given location of transition for temperature distribution is proposed. Base on this model, the structural thermal mode considering thermal stress and material inherent characteristics is analyzed. Finally the aeroelasticity is analyzed by the method of local flow piston theory based on CFD. This paper chooses an all-movable control surface as study subject with M = 6, H = 15 km and the calculation results show that: (1) As the transition location moving from leading edge to trailing edge, the structural frequencies increase and flutter velocity has an increased trend. Research indicates that maximum variation of flutter velocity is 6% brought by transition location; (2) When transition is located near the rudderpost, the flutter characteristics of the structure change violently. Decomposition and analysis of stiffness characteristic show that the major factor is the stiffness of rudderpost whose influence accounts for more than 80% of the whole structure.