Analysis on flow characteristics and aerodynamic-force-induced vibration of supersonic rocket-sled

超声速火箭橇流动特征和气动力激励振动分析

¹ Key Laboratory of Aircraft Environment Control and Life Support, MIIT, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
² Key Laboratory of Civil Aviation Emergency Science and Technology, CAAC, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China

Received: 12 January 2022

Abstract

目前, 火箭橇试验是飞行器空气动力学重要试验手段, 然而强烈的地面与轨道干扰会影响试验的精度, 甚至导致试验失败。采用尺度自适应SAS方法和基于铺层算法的动网格技术对不同马赫数下的超声速火箭橇滑行过程进行数值模拟, 探究了超声速火箭橇的气动力致振机理。采用了数值风洞模拟方法对超声速火箭橇无限空间绕流和仅包含地面的橇体绕流进行仿真, 分析了不同环境条件下的激波特征。结果表明: 超声速火箭橇的头激波传播至轨道和地面时会发生激波反射, 反射激波的存在会导致超声速火箭橇产生升力, 并带来阻力的略微增加; 反射激波与轨道扣件的周期性碰撞使得其尾迹区具有非定常特征; 火箭橇的气动力激励振动频率与尾迹波动频率一致, 即气动力激励振动对非定常尾迹具有锁频现象。此外, 压力信号的功率谱密度分析表明气动力激励振动存在谐声现象, 这与锁频现象密切相关。

摘要

Nowadays, the rocket-sled test is an important experimental method of vehicle aerodynamics, while the experimental accuracy will be badly affected by the strong interaction of ground and orbit, even leading to the testing failure. Numerical simulations of supersonic rocket-sled during dynamic gliding at different Mach numbers were carried out by using a scale-adaptive simulation (SAS) method and a dynamic grid technique based on a tiling algorithm, and the aerodynamic-force-induced vibration mechanism of supersonic rocket-sled was investigated. Numerical wind tunnel technique was also used to simulate the supersonic flow around rocket-sled in the infinite and ground-only environmental space, and the shock wave characteristics at different environmental conditions were analyzed. Study results shown that: the head-shock of supersonic rocket-sled propagated to the orbit and ground with a reflected shock; For the supersonic rocket-sled, the presence of reflected shock leaded to the generation of lift and a slight increase of drag; The unsteady wake was closely associated with the periodic collision between the reflected shock and rail fasteners; The aerodynamic-force-induced vibration frequency of supersonic rocket-sled was equal to the wake fluctuation frequency, i.e., the aerodynamic-force-induced vibration had a frequency locking effect on the unsteady wake. Furthermore, the power spectral density analysis of pressure signal shown that there was a harmonic phenomenon in the aerodynamic-force-induced vibration, which was closely related to the frequency locking phenomenon.