吸气式高超声速飞行器大迎角气动特性分析

吸气式高超声速飞行器在飞行过程中受到大气紊流等外部干扰的作用时,飞行姿态很可能会出现大迎角情况。针对大迎角飞行时飞行器可能出现的气动问题,对一种典型吸气式高超声速飞行器的流场进行了数值模拟。以雷诺平均Navier-Stokes(RANS)方程为控制方程,采用标准k-ε湍流模型求解,得到其流场特征和气动特性。重点针对大迎角情况,分别对整机气动特性、进气道性能和全动尾翼气动性能进行了分析,并结合流场特征作出解释。结果表明,机身和发动机之间存在气动/推进耦合现象。大迎角下飞行器的气动参数表现出非线性特性,升阻比减小,整机纵向表现为静不稳定,且不稳定性随迎角增大而增大;进气道性能在大迎角下降低,从而导致发动机推力下降,不利于发动机的正常工作,但却适当降低了整机的纵向静不稳定度;全动尾翼操纵效率降低从而使得配平难度增大。

Aerodynamic characteristics analysis of air-breathing hypersonic vehicles at high angle of attack

During the flight of air-breathing hypersonic vehicles, the atmospheric turbulence or other external disturbances may result in high angle of attack conditions. In order to study the aerodynamic performances influenced by high angle of attack, numerical simulations are performed on the flow field of a typical air-breathing hypersonic vehicle. The flow field and aerodynamic characteristics are obtained by solving the Reynolds-averaged Navier-Stokes (RANS) equations using standard k-ε turbulence models. The performances of vehicle, inlet and the all-moving tails are analyzed and explained based on the flow field characteristics especially at high angle of attack. The investigation indicates that there is coupling between aerodynamics and propulsive system. At high angle of attack, aerodynamic parameters exhibit nonlinear characteristics, meanwhile, the lift-to-drag ratio begins to reduce and the longitudinal instability enhances. The inlet has poor performance at high angle of attack, resulting in the decrease of thrust provided by the engine, which is not conducive to the normal operation of the engine. However, on the other hand, the decrease of thrust will reduce the longitudinal instability of the vehicle. In addition, the control efficiency of the all-moving tails reduces and consequently makes trimming difficult.