Numerical investigation of spike-assisted transpiration cooling for a hypersonic leading edge: Shock-wave regulation and coolant redistribution

High external pressure in the stagnation region can suppress coolant discharge through porous walls and limit transpiration cooling for hypersonic leading edges. To alleviate this constraint, a combined spike–transpiration cooling configuration is proposed to couple shock-wave regulation with coolant transport. A conjugate numerical model of the freestream, porous medium, and solid wall is developed using the SST k–ω model, the Brinkman–Forchheimer formulation, and species transport, and is validated against separate experimental datasets for transpiration cooling and spiked-body aerothermal flow. The spike reduces the wall static pressure at the stagnation point from 115.20 to 62.78 kPa, a decrease of 45.5%, thereby facilitating coolant discharge. Compared with transpiration cooling alone, the combined configuration reduces the wall temperature at the stagnation point by 49.5%. It also lowers the reattachment-induced shoulder temperature peak by 34.4% relative to the spike-only configuration. As the angle of attack increases from 2° to 6°, the mean cooling effectiveness decreases from 0.75 to 0.70 on the windward side but increases from 0.81 to 0.87 on the leeward side because of pressure-driven coolant redistribution. Increasing the spike length-to-radius ratio (l/R) from 1 to 2 shifts coolant toward the leading-edge high-heat-flux region and raises the mean cooling effectiveness from 0.76 to 0.82. The results demonstrate that shock-wave regulation and distributed coolant transport act synergistically to mitigate stagnation and reattachment heating.