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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。
In the low turbulence wind tunnel of Northwestern Polytechnic University, the instability of transverse flow and its transition pattern in the three-dimensional boundary layer of 45 ° swept wing were studied by sublimation method. Without the introduction of artificial rough band, the Reynolds number is in the range of 5.50 × 105 ~ 1.65 × 106, the transition boundary of the model is always a straight line after the minimum pressure point, and the transition is triggered by the T-S wave. When Re≥1.38 × 106, the 3.5 ~ 4.0mm fringe corresponding to the most unstable transverse flow standing wave appears in the upstream region of the transitional ridge. The fringe spacing agrees well with the linearized stability theory. When Re = 1.65 × 106, experiments show that the transverse current standing wave disturbance is extremely sensitive to the leading edge roughness. Considering that the most unstable standing wave is suppressed, it is possible to restrain the predominant rotation of the swept-back wing aircraft and to arrange the rough bands with different pitches on the leading edge of the wing to study its effect on the standing wave in the boundary layer. When Re = 1.38 × 106, the rough band with 2.5mm pitch effectively suppresses the most unstable standing wave of 3.5 ~ 4.0mm. This phenomenon provides a new idea for the control technology of revolving around the swept wing. In addition, the fringe intervals appear as harmonic wavelengths of 3.0 mm, 3.5 mm, and 4.0 mm when a rough band of 6.0 mm, 7.0 mm, and 8.0 mm is introduced.