Analysis of hypersonic plasma flow field evolution and wake particle distribution characteristics under thermochemical–mechanical ablation

To investigate the effects of carbon–carbon (C–C) material ablation on the plasma-flow characteristics of hypersonic vehicles under high-enthalpy conditions, this study combines multiphysics numerical simulations with plasma-wind tunnel experiments. First, a coupled thermochemical–mechanical ablation model was established to describe the transport of carbon-based gaseous products and solid particles in the near-wall region, wake region, and downstream diffuser region. The numerical results indicate that ablation products affect the local flow-field parameters through mass blowing, near-wall blockage, and chemical deionization effects. Second, based on the Experimental research apparatus for electromagnetic science of hypersonic vehicle plasma in nearspace, electron-density measurements were conducted using electrostatic probes under the plasma wind tunnel (PWTs) ablation condition with the C–C ablating model. The results show that C–C ablation reduces the peak electron density near the stagnation region. Owing to the downstream transport of ablation products, the electron-density distribution exhibits a characteristic trend of reduced peak value and expanded affected range. The difference between the electron-density measurements and numerical predictions under the same wind tunnel operating condition is within 10%. Finally, the spatiotemporal distribution of mechanically eroded particles in the wake and diffuser regions was analyzed. The numerical results reveal a spatial correlation between geometry-induced recirculation and near-wall particle enrichment in the diffuser. By combining the blockage-ratio evolution with the Kantrowitz-based theoretical reference, an assumption-dependent equivalent blockage ratio was introduced for a preliminary engineering assessment of potential diffuser blockage risk. This provides a numerical and experimental reference for evaluating particle accumulation risks during high-power PWT operation.