论文部分内容阅读
安装在超声速/高超声速飞行器表面的突起物如机翼、控制舵等通常会导致复杂的激波/边界层干扰,对突起物的局部气动特性甚至飞行器整体的气动特性产生较大的扰动。在采用计算流体力学(CFD)数值模拟此类问题时,传统的求解雷诺平均Navier-Stokes(RANS)方程方法由于不能准确预测湍流脉动流场并且精度有限,在应用上受到一定的限制。本文在研究B-L(Baldwin-Lomax)内层模型和Smagorinsky亚格子模型优缺点的基础上,提出了一种新型的RANS/LES(Large Eddy Simulation)混合模型,并进行了算例验证,证实了该方法的可行性。在此基础上,对火箭表面突起物的干扰流场进行了数值模拟研究,细致地刻画了突起物附近的激波/边界层干扰、剪切层失稳和底部分离涡形成的非定常过程,获得了突起物及火箭表面上的压力脉动历程并进行了频谱分析。研究发现,相对于突起物底部的非定常分离流动,突起物前缘的激波和边界层相互干扰的非定常过程是突起物周围压力脉动的主导因素,这种高频的压力脉动可能对火箭内设备的正常工作产生不利的影响。
Protrusions installed on the surface of supersonic / hypersonic vehicles, such as wings, control rudders and the like, usually result in complicated shock / boundary layer interference and cause large perturbations on the local aerodynamic characteristics of the bump and even the aerodynamic characteristics of the aircraft as a whole. When CFD numerical simulation is used to simulate this kind of problem, the traditional method to solve the Reynolds-averaged Navier-Stokes (RANS) equations is limited in application because of its inaccurate prediction of turbulent pulsating flow field and its limited accuracy. Based on the research of the Baldwin-Lomax inner model and the Smagorinsky sub-lattice’s advantages and disadvantages, a new hybrid model of RANS / LES (Large Eddy Simulation) is proposed and verified by examples. Feasibility of the method. On this basis, the numerical simulation of the disturbed flow field of the rocket surface protuberance was carried out. The shock wave / boundary layer disturbance, the instability of the shear layer and the unsteady flow of the bottom separation vortex were described in detail. The pressure pulsations on the protuberances and rocket surfaces were obtained and analyzed. It has been found that the unsteady process of the shock at the leading edge of the protuberance and the interference with the boundary layer is the dominant factor of the pressure pulsation around the protuberance, relative to the unsteady separation flow at the bottom of the protuberance. This high-frequency pressure pulsation may affect the rocket The normal operation of the equipment has an adverse effect.