A multi-physics thermochemical non-equilibrium model is established to study the flow characteristics of the plasma sheath around an atmospheric reentry demonstrator. This model includes the tight coupling of Navier–Stokes equations, 54 chemical reactions of air, and a four-temperature model. The processes of dissociation, ionization, and the internal energy exchanges of air components were successfully simulated during aerodynamic heating of the reentry vehicle. The distributions of plasma sheath temperature, the molar fraction of air species, stagnation pressure, surface pressure, and electron number density around the reentry vehicle were obtained at different flight altitudes. Additionally, to validate the numerical model developed in this study, the flow characteristics of the Radio Attenuation Measurement-C-II (RAM-C-II) vehicle are also simulated and then compared with corresponding experimental data. They show good consistency in general. It is found that when the vehicle is at a high flight altitude, there is a strong thermochemical non-equilibrium phenomenon around the vehicle. However, the plasma sheath tends to be in local thermal equilibrium at a low flight altitude. The distance from the shock layer to the stagnation point decreases with a decrease in reentry altitude from 90 to 65 km but increases with a decrease from 65 to 40 km. The electron number density in the shock layer is maximum. The distribution of the electron number density in the wake region differs significantly at different flight altitudes.

Jet mixings of a coplanar alternating-lobe nozzle (CoALN), scarfing alternating-lobe nozzle (ScALN), sword alternating-lobe nozzle (SwALN), and sword and chevron alternating-lobe nozzle (SwChALN) were numerically investigated using three different far-field velocities to simulate the conditions of pumping air intake and stamping air intake. It was confirmed that the stamping air intake can be introduced to increase the cool air involved in the mixing for an infrared suppressor of a helicopter. It was found that the stamping air intake increases the amount of cool stream near the mixing tube, which can effectively decrease the temperature of the mixing tube, thus improving the infrared suppression performance. Under the two intake conditions, for a normal infrared suppressor with a short mixing tube, SwALN and SwChALN are recommended; however, for an integrated infrared suppressor with a long mixing tube, CoALN and ScALN should be adopted. The shape of the longitudinal vortices is closely related to the large-scale heat and mass convection. The plumper longitudinal vortices can bring faster mixing to the affected region.

To investigate the aerodynamic characteristics of the subsonic transport standard model (DLR-F4 wing–body configuration), this study uses the Spalart–Allmaras Detached Eddy Simulation (SA-DES) turbulence model as the core, coupling it with fifth-order WENO/WCNSs and HLLC approximate Riemann solver for numerical simulations under different angles of attack (AOA). Through comparative simulations, effects of grid density, turbulence models (URANS/DES), and spatial discretization schemes (second-order CDS, fifth-order WENO-JS/WCNS-JS) on accuracy are analyzed, focusing on grid convergence and numerical scheme dissipation in separated flows. The results show medium-density grid results are stable, balancing accuracy and efficiency. Under high AOA, DES outperforms URANS in capturing separated vortex structures, effectively reproducing small-scale vortices in the wing–body junction. High-order WCNS performs best in predicting wing-tip vortices and wake turbulence due to lower dissipation. WCNS-JS/WCNS-T (different weight functions) affect lift/drag coefficient errors: WCNS-JS has smaller lift prediction errors, while WCNS-T better reduces dissipation and maintains wing-tip vortex integrity. This study provides key references for high-accuracy simulations of complex separated flows, supporting efficiency improvement and accuracy optimization in aerospace vehicle aerodynamic design.

In this paper, the detached eddy simulation (DES) method is used to calculate the aerodynamic characteristics of NACA0015 airfoil by combining the Riemann approximate solution HLLC (Harten–Lax–van Leer Contact) with the high-order weighted essentially non-oscillatory (WENO) scheme and the weighted compact nonlinear scheme (WCNS), respectively. By comparing the calculation results of the two different numerical schemes with the wind tunnel test results, it is found that both numerical schemes can accurately calculate the aerodynamic parameters at small angles of attack. However, in the range of near-stall angle (in the range of 10–15°), the calculation results of various numerical schemes have a certain degree of deviation. The calculation results of the fifth-order WCNS and the fifth-order WENO scheme are closer to the experimental values. The fifth-order WCNS predicts the stall angle of attack more accurately than the fifth-order WENO scheme. The calculation accuracy of the fifth-order WCNS is better than that of the fifth-order WENO scheme under the post-stall condition (where the angle of attack is greater than 15°). By comparing the vorticity contours calculated by different numerical schemes, it is found that the numerical dissipation of the fifth-order accuracy is smaller than that of the third-order accuracy, and the vortex capture ability is stronger. WCNS captures the small vortex structure that the WENO scheme does not.