Near-wall vortices and thermal simulation of coupled-domain transpiration cooling by a recursive regularized lattice Boltzmann method

The present study aims to reveal the near-wall vortices and the effects of flow states in coupled-domain transpiration cooling using a recursive regularized thermal lattice Boltzmann method (RR-TLBM). Large-eddy simulations of turbulent flow and heat transfer have been conducted on high-resolution computational grids using a desktop-level computer with CUDA 11.6. Results indicate that the near-wall flow structures present spatial characteristics along the streamwise direction. The vortex evolution promotes the downstream heat dissipation, even though turbulence impairs the effective cooling area. The spanwise evolvement of vortices strengthens the mixing of coolant and hot gas, and small-scale structures are beneficial for turbulent heat transfer. Moreover, the transition onset occurs earlier at higher Reynolds numbers, and it weakens the downstream cooling. The cooling performance of the derived coolant film is improved as the Reynolds number varies from 5 x 10(3) to 3 x 10(4) with a blowing ratio of F = 10%, whereas the local cooling is impaired at the high Reynolds numbers exceeding 5 x 10(4). The variation in flow states has little influence on the cooling performance at the Reynolds numbers larger than 3 x 10(6). On the other hand, our in-house RR-TLBM solver is highly stable and efficient for the simulation of flow and heat transfer with high Reynolds numbers. Simultaneously, a high computational performance of 1127 million lattices updated per second is achieved for our simulation of a coupled-domain turbulent flow and heat transfer, using the desktop-level computer with three Tesla V100 graphics processing units. Published under an exclusive license by AIP Publishing.

Automated summary

This study uses a recursive regularized thermal lattice Boltzmann method (RR-TLBM) to investigate near-wall vortices and the effects of flow states in a coupled-domain transpiration cooling system. The results show that near-wall flow structures exhibit spatial characteristics in the streamwise direction, and vortex evolution promotes downstream heat dissipation. The study also found that small-scale structures are beneficial for turbulent heat transfer. The cooling performance of the coolant film improves at lower Reynolds numbers but is impaired at higher Reynolds numbers.