后掠翼边界层横流不稳定性的实验研究(英文)

在西北工业大学的低湍流度风洞中,采用升华法研究有无粗糙带情况下,45°后掠翼三维边界层内的横流驻波不稳定性及其转捩模式。在未引入人工粗糙带,雷诺数为5.50×105~1.65×106范围内,模型的转捩分界始终为位于最小压力点之后的一条直线,转捩由T-S波触发。当Re≥1.38×106时,对应最不稳定横流驻波的3.5~4.0mm条纹出现在转捩的上游区域,条纹间距与线化稳定性理论的结果吻合。当Re=1.65×106时,实验证实了横流驻波扰动对前缘粗糙度的极度敏感。考虑到抑制最不稳定横流驻波就很有可能抑制后掠翼飞行器上由其主导的转捩,在机翼前缘布置不同间距的粗糙带,研究其对边界层内横流驻波的影响。当Re=1.38×106时,2.5mm间距的粗糙带有效的抑制了3.5~4.0mm最不稳定驻波,该现象为后掠翼上的转捩控制技术提供了一条新思路。此外,当6.0mm、7.0mm和8.0mm的粗糙带被引入时,条纹间隔表现为3.0mm、3.5mm和4.0mm的谐波波长。

Experimental investigation of cross-flow instability in swept-wing boundary layers

Stationary cross-flow instabilities and transition pattern in the boundary layer of a 45° swept wing with and without 3D artificial leading edge roughness were investigated by sublimation method.For the model without artificial roughness,straight transition lines behind the minimum pressure point which are dominated by T-S instabilities appeared in the Reynolds number range of 5.50×105～1.65×106.When Re≥1.38×106,traces of the most amplified stationary cross-flow waves were detected,and 3.5～4.0mm spacing stripes agreed quite well with the results of linear stability theory.The extreme sensitivity of the stationary disturbance to leading edge roughness is verified at Re=1.65×106.In order to modify the most amplified cross-flow waves which usually dominate transition on the swept wing of an aircraft,different spacing leading edge roughness were applied.At Re=1.38×106,2.5mm spacing roughness suppressed the most amplified waves and showed the potential ability to suppress the transition dominated by stationary cross-flow waves.In addition,half of the input wavelengths which attribute to harmonics appeared when 6.0～8.0mm spacing roughness printed.