Infrared thermogram measurement experiment of hypersonic boundary-layer transition of a lifting body

For a lifting body model, the boundary layer transition infrared thermogram measurement experiment was carried out in the conventional hypersonic wind tunnel, and the influence of different unit Reynolds number and Mach number on the lifting body boundary layer transition was studied, which was compared with the calculation results of the e^N method. The length of the experimental model is 800 mm, the unit Reynolds number is 0.46 × 10⁷ – 3.94 × 10⁷ m^–1, the Mach number is 5 – 8, and the angle of attack is 0°. The transition position and transition front of the boundary layer on the surface of the model are obtained by the large-area infrared thermogram technology. The analysis of the experimental results shows that there are crossflow instability and the second mode transition in the boundary layer of the lifting body. As the unit Reynolds number increases, the crossflow transition effect increases, the temperature rise on the lower and upper surfaces of the model increases, the transition front moves forward, and the transition area expands; as the Mach number increases, the crossflow transition effect gradually weakens and the transition position moves downstream, and the transition area significantly shrinks back. Moreover, the transition N factor at different Mach numbers and unit Reynolds numbers are relatively close, but the N factors of the upper and lower surfaces are different. The lower surface is about 6, and the upper surface is about 2.5. The high-frequency second mode transition occurs in the side edge at high unit Reynolds numbers.