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Acta Aeronautica et Astronautica Sinica ›› 2025, Vol. 46 ›› Issue (2): 130464.doi: 10.7527/S1000-6893.2024.30464

• Fluid Mechanics and Flight Mechanics • Previous Articles    

Effect of distributed ablation pattern on hypersonic boundary-layer instability with a flat plate

Xueliang LI1, Chuangchuang LI1, Yahan ZHANG1, Wei SU2, Jie WU1()   

  1. 1.School of Aerospace Engineering,Huazhong University of Science and Technology,Wuhan 430074,China
    2.Beijing Institute of Space Long March Vehicle,Beijing 100076,China
  • Received:2024-03-29 Revised:2024-06-03 Accepted:2024-06-21 Online:2024-06-28 Published:2024-06-25
  • Contact: Jie WU E-mail:jiewu@hust.edu.cn

Abstract:

After experiencing high-temperature ablation, the thermal protection material on the surface of hypersonic vehicle exhibits a pattern of distributed roughness element. However, the effect of such pattern on hypersonic boundary layer transition and its influencing mechanism have not been recognized at present, which has attracted the attention of researchers. Wind tunnel experiments are carried out based on the ∅0.5 m Mach number 6 Ludwieg tube wind tunnel of Huazhong University of Science and Technology. The evolution of instability waves in the hypersonic boundary layer of the flat plate is studied in the cases of smooth and distributed roughness elements with four heights of 0.5, 1.0, 1.5, 2.0 mm and various of Reynolds number at 5.39 × 106 m-1 to 1.72 × 107 m-1. The effects of distributed roughness element height and incoming Reynolds numbers on the boundary layer instability of a flat plate are clarified. The experimental results show that the second mode instability waves dominate the instability of the hypersonic boundary layer in the case of distributed roughness element, and the frequency range is about 60 kHz to 120 kHz. For the distributed roughness element which is lower than the local boundary layer thickness, the height factor has little influence on the transition position of the hypersonic boundary layer. The influence of height of the distributed roughness element on the flow velocity of the second mode instability waves in the hypersonic plate boundary layer is non-monotonic, and there is a critical height that has the greatest influence. Under the inflow conditions of different Reynolds numbers, the characteristic evolution of the second mode instability waves in the smooth and roughness cases is basically the same, and the boundary layer transition positions of roughness elements at different heights have little difference with the inflow of the same Reynolds number.

Key words: hypersonic, ablation pattern, boundary layer transition, instability, flat plate model, wind tunnel test

CLC Number: