Numerical simulations on the performance of transpiration cooling implemented with perforated flat plates

Transpiration cooling is an effective method of protecting high-temperature components. However, this tech-nology is currently not applicable to turbine blades because conventional sintered porous materials cannot precisely control the geometric parameters of the cooling channels and coolant outlets. In this study, numerical simulations using the conjugate heat transfer method were conducted to study the effects of hole diameter, injection ratio, and mainstream Reynolds number on the cooling performance of perforated flat plates. A novel optimisation method for the overall transpiration cooling efficiency that reduces coolant consumption through a nonuniform coolant allocation strategy was proposed. The effects of different pore diameters (0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm) on transpiration cooling were investigated numerically. The results revealed that the hole diameter had a marginal effect on the average cooling efficiency of transpiration cooling under the same coolant-injection ratio. With dense heat transfer occurring within the solid matrix, the influence of variations in the pore size was diminished. However, the nonuniformity of the cooling efficiency on the hot wall surface increased with increasing pore size. A double coolant chamber non-uniform injection was adopted for the 0.3 mm perforated plate. The results indicated that there is an optimum coolant allocation ratio for achieving the highest average cooling efficiency with a certain coolant.