Numerical study on the near-wall characteristics of compound angled film cooling based on hybrid thermal lattice Boltzmann method

Massively parallel simulation based on hybrid thermal lattice Boltzmann method (HTLBM) is performed to analyze the near-wall flow and heat transfer characteristics in compound angled film cooling. Multiple graphic processing units (Multi-GPUs) are used to speed up the computations. The effect of compound angle on the instantaneous flow characteristics and cooling performance with various blowing ratios and inclined angles are studied in detail. In the simulation, three compound angles of β=15°,30°,45° are considered. The inclined angles of coolant jet to the flat surface are set to α=30° and α=60° respectively. The blowing ratios are BR=0.5 and BR=1.0. It is observed that the application of compound angle enhances the mixing between the crossflow and the jet flow, especially for the large-blowing-ratio cases. The detachment of the coolant jet is reduced by applying compound angle, which results in the increasing of film cooling effectiveness, particularly in the case of small jet inclined angle α. Moreover, to reasonably evaluate the uniformity of coolant film in compound angled film cooling, a novel coefficient (COU) affording a wide application is proposed in the present work. The results show that the coolant-film uniformity is decreased by the application of compound angle.