Abstract An experiment investigating the second-mode instability on the sharp cone with a small angle of attack has been conducted. The fine structure in the boundary layer has been visualized by the Nano-tracer-based Planar Laser Scattering(NPLS) technique. The “rope-like” second-mode waves are found to still be the dominant structures before the transition of the boundary layer at 1 ° angle of attack and the leeside-forward and windside-aft of the transition have also been verified. The propagation velocity of the second-mode waves on the leeward side increases obviously as the disturbance evolving downstream. The development of the disturbance has been analyzed through the wall-fluctuation pressure. The amplification of amplitude is nonmonotonic along the circumferential direction and the M-factor patterns indicated that the disturbance development is delayed in three indentation regions: 55 ° ⩽ φ ⩽ 65 ° , 85 ° ⩽ φ ⩽ 95 ° and 130 ° ⩽ φ ⩽ 140 ° .

中文翻译：

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锥体小攻角高超声速边界层中二阶模态波的实验研究

摘要 进行了小攻角尖锥第二模态不稳定性的实验研究。边界层中的精细结构已通过基于纳米示踪剂的平面激光散射 (NPLS) 技术可视化。在1°攻角边界层过渡之前，发现“绳状”第二模式波仍然是主导结构，并且过渡的背风-前和风侧-后也得到了验证。随着扰动向下游演化，背风侧二模波的传播速度明显增加。通过壁面波动压力分析了扰动的发展。