定几何混压式轴对称超声速进气道的稳定性实验

对一种定几何混压式轴对称超声速进气道的稳定性进行了风洞实验研究,得到了不同状态下进气道的纹影图片、沿程静压分布以及进气道性能随出口马赫数的变化曲线,并进行了分析。结果表明:在超临界工作范围内,随着反压提高结尾激波系前移,进气道出口马赫数下降,总压恢复系数升高,而流量系数保持不变。当工作马赫数大于封口马赫数时,本研究中的混压式进气道亚临界工作状态存在稳定状态,而当马赫数低于封口马赫数时,进气道亚临界状态不稳定。

Experiment on Stability for Mixed-Compression Axisymmetric Supersonic Inlet with Fixed-Geometry

The stability of the mixed-compression axisymmetric supersonic inlet with fixed-geometry is investigated in a supersonic wind tunnel.The Schlieren photographs of the inlet,the static pressure along the duct and the influence of the Mach number at the exit on the performance of the inlet are analyzed in different operations.The result indicates that:(1) In supercritical operation the total-pressure recovery increases with the decline of the Mach number at the exit, while the mass-flow ratio keeps almost constant.(2) The subcritical operation of the mixed-compression inlet has two states when the Mach number of the design is less than the maximum Mach number of the operation.If the Mach number of the coming flow exceeds the Mach number of the design,the status of subcritical operation of the mixed-compression inlet is similar with the external-compression inlet,so the inlet is stable,on the contrary the shock shakes up and down stream along the cone,therefore the inlet is unstable.(3) When the inlet is in unstable in subcritical operation,the backpressure at the exit,the mass-flow ratio and the total-pressure recovery fall rapidly as the Mach number at the exit climbs.(4) When the inlet is in stable subcritical operation,despite of the drop of the mass-flow ratio and the Mach number at the exit,the backpressure at the exit and the total-pressure recovery fluctuate with the bowed shock moving forward.(5) For the sharp variation of the static pressure at the region near throat,the separation of the flow is avoided,thus improving the stability of the inlet.