Flow structure and heat transfer of transpiration cooling by using a LBM: The effects of wall blowing and spatially nonuniform injection

Considering the effects of wall bowing and spatially nonuniform injection, the near-wall flow structures and heat transfer characteristics in transpiration cooling are studied through numerical simulations by an in-house thermal lattice Boltzmann solver accelerated by GPGPUs. Results reveal that the development of coolant layer is influenced by local velocity gradients, and a wall blowing ratio of larger than 2%–3% induces the flow separation and unstable coverage of low-temperature layer, and that the coolant injection weakens the surface friction coefficient, while the flow separation facilitates a local increase of the skin friction coefficient downstream the wall. For nonuniform injection, the local increases of mass and momentum with the peak velocity of nonuniform injection is beneficial to the coolant-layer development but the spatial temperature control is unstable, indicating the stable development and coverage of coolant layer are the key factors of the flow and heat transfer in transpiration cooling process.