动态迎角条件下超声速进气道气动特性研究

Study on Aerodynamic Characteristics of Supersonic Inlet under Dynamic Angle of Attack

高超声速飞行器迎角振荡与燃烧引起的反压振荡共同作用会对高超声速进气道的工作状况产生重要影响,本文通过壁面测压、高速纹影等方法,开展了稳态迎角与动态反压、动态迎角与稳态反压、动态迎角与动态反压三种条件下超声速进气道气动特性的试验研究。研究结果表明,进气道迎角变大时,气流偏转角变大,前体压缩波系增强,进口马赫数降低,下游反压增大,会使进气道更容易进入不起动状态;进气道在迎角和反压同时发生动态变化的条件下,比单一变化时更容易不起动;在进气道出现激波串之前,截流面积比增加并不会造成反压增大;截流面积增大的速率越高,进气道不起动时的截流面积比越大;进气道的喘振频率与迎角大小有关,当截流面积比相同时,进气道在大迎角时喘振频率更高;当动态迎角滞后于动态反压较大相位差时,进气道在更大的迎角下才发生不起动,表明进气道能在更大的迎角下正常工作;但当进气道不起动后,进气道需要在达到更小的迎角时才能实现再起动。

The combined effect of angle of attack oscillation and back pressure oscillation caused by combustion in hypersonic aircraft can have a significant impact on the working condition of hypersonic inlets.This paper conducts experimental research on the aerodynamic characteristics of the supersonic inlet under three conditions:Steady-state angle of attack and dynamic back pressure,dynamic angle of attack and steady-state back pressure,and dynamic angle of attack and dynamic back pressure,using methods such as wall pressure measurement and high-speed schlieren imaging.Results show that as the attack angle of the inlet increases,the airflow deflection angle increases,the front body compression wave system strengthens,the inlet Mach number decreases,and the downstream back pressure increases,which makes it easier for the inlet to enter an unstarting state;Under the condition of dynamic changes in angle of attack and back pressure simultaneously,the inlet is more likely to not start than under a single change;Before the shock train appears in the inlet,an increase in the interception area ratio does not cause an increase in back pressure;The higher the rate at which the interception area ratio increases,the greater the interception area ratio when the inlet does not start;The buzz frequency of the inlet is related to the size of the angle of attack,when the interception area ratio is the same,the buzz frequency of the inlet is higher at large angles of attack;When the dynamic angle of attack lags behind the dynamic backpressure with a large phase difference,the inlet does not start at a larger angle of attack,indicating that the inlet can operate normally at a larger angle of attack;But when the inlet does not start,it needs to reach a smaller angle of attack before it can restart.