One way to address the thermal protection issue of hypersonic vehicles is through wall mass injection, which can successfully lower skin friction and wall heat flow. The effects of three distinct gases (pyrolysis gas, water vapor, and carbon dioxide) on aerodynamic force and thermal characteristics are compared and analyzed, and the numerical simulation of mass injection on the heat flux and skin friction of the wall is investigated using a two-dimensional blunt wedge as the calculation model. It is possible to determine that the pyrolysis gas injection lowers the convective and diffusion heat flux by splitting the heat flux into these two categories. Both carbon dioxide injection and water vapor enhance the diffusion heat flux while decreasing the convective heat flow. The effect of water vapor raising the diffusion heat flux is more noticeable, leading to an increase in the overall heat flux. Additionally, by lowering the velocity gradient close to the wall, all three gases can lessen the skin-friction of the wall, with pyrolysis gas injection having a greater impact.

The RANS/NLAS coupling method is used to simulate and optimize the fluctuating pressure environment of a rocket fairing under transonic conditions. The results indicate that the RANS/NLAS method can accurately simulate the fluctuating pressure with less grids. When transonic flow passes the rocket fairing, shock waves/boundary layer interaction occurs at the shoulder, and a large separation region is formed at the inverted cone, thus the fluctuating pressure environment is severe on both the shoulder and the inverted cone. With the increase of the attack angle, the fluctuating pressure environment on the leeward side of the shoulder becomes severe, but that on the inverted cone region tends to be alleviated. To optimize the fluctuating pressure environment at the inverted cone, three new outline profiles of the inverted cone are designed, i.e. the straight line shape, the sinusoidal line shape and the “tangent arc + circular arc” shape, respectively. The time-averaged friction coefficient C_f, separation region, root-mean-square pressure coefficient C_{p_rms} of the three designs are compared, and the result shows that the “tangent arc + circular arc” design is the most effective in optimizing the fluctuating pressure environment.

This paper performs numerical simulation on the decompression process of a Mars rover using FLUENT. The pressure differential between the inside and outside of the Mars rover resulting from changes in ambient pressure of the rocket fairing is investigated. In terms of numerical simulation, PROFILE outlet boundary conditions are developed and the impacts of ambient pressure settings, time steps, and mesh density are investigated to improve the accuracy of simulation results. The decompression process of the separate large module, large and small modules under two types of ambient pressures are simulated. The results show that the largest pressure differential between the inside and outside of the module body is less than 2200 Pa. Because of the small size of the small module, the results for the separate large module and the large/small modules are consistent. The pressure differential between the inside and outside of the rover is mainly influenced by the variation in ambient pressure.