Study on flow characteristics in narrow gap between slipper and rail on hypersonic rocket sled

During the operation of hypersonic rocket sleds, the flow phenomenon in the gap between the slipper and the rail is relatively complex, and the high-temperature and high-pressure environment will affect the safety of the test. The article investigates the effects of shock waves on the velocity, temperature, pressure, and viscosity coefficient of the narrow gap inlet. Three narrow gap models at Mach 4 are numerically calculated using CFD software. It is found that, firstly, the leading-edge temperature of the narrow gap is around 1350-1500 K, which could potentially cause damage to the slipper. Secondly, the inlet structure results in lower velocity and temperature and higher pressure in the velocity field at the front of the narrow gap. However, it has no effect on the velocity field at the back of the narrow gap. Thirdly, when influenced by three-dimensional effects, the flow velocity within the gap reduces, while the temperature in the rear part rises. Additionally, we explored the influence of gap height (0.3 to 0.7 mm) and Mach number (4 to 8) on the confluence point position, the thickness of the wall boundary layer in the gap. The research provides important guidance for the study of the gouging phenomenon and thermal analysis of the slipper.