平头增阻再入体俯仰动态特性计算与流动机理分析

采用自由振荡法数值模拟了一种平头增阻再入体的高超声速俯仰动态特性,沿用稳定性导数模型作为动态特性的指标,通过把稳定性导数视为攻角的函数来考虑非线性影响,并应用奇异分解线性最小二乘法辨识稳定性导数。对于本文研究对象,计算结果表明,平头外形在较高马赫数和小攻角范围内存在动不稳定现象,随着再入时马赫数的降低,动不稳定的攻角范围不断缩小,直至演化为动稳定的。文中对平头外形出现这种动态特性现象的空气动力学原因进行了分析,有必要作进一步的确证与研究。

Pitching dynamic stability computation for plane nose reentry vehicle and flow mechanism analysis

In this paper,the pitching dynamic stability derivatives are computed by an unsteady CFD method for a plane nose reentry vehicle at hypersonic free flow.The dynamic derivatives conception is used as the index for the vehicle dynamic stability,but it is looked as the function of angle of attack and Mach number to induced nonlinear characteristics.The dynamic stability derivatives are fitted by the singularity decomposition linear least square method.For the plane nose reentry vehicle researched in this paper,the computational results show it is unstable at the higher Mach number and small angle of attack,with the decrease of Mach number in reentry,the range of angle of attack in which the vehicle is unstable is reduced,and a critical Mach number between 6.0 and 7.0 exist,if the free flow Mach number is below at the critical Mach number,the vehicle should be stable at all angle of attack.The flow mechanism for such dynamic stability characteristics is also analyzed in this paper,and a new flow mechanism for plane nose vehicle losing stability at hypersonic is introduced,but it should be researched more carefully.