Improved prediction accuracy of trailing edge cutback cooling effectiveness with turbulent viscosity correction

Trailing edge cutback cooling structures are widely used because of their good aerothermal performance. However, owing to the nonlinear mixing between the shedding vortex and the jet, the film cooling effectiveness on the cutback surface is still difficult to predict accurately. The traditional Reynolds-Averaged Navier‒Stokes method has high computational efficiency, but its accuracy is insufficient in simulating complex flows such as fluid mixing and vortex interactions. Therefore, on the basis of turbulent viscosity theory and the SST k‒ω turbulence model framework, this work proposes a component transport correction model, the “PLF model,” for trailing edge cutback cooling. The model introduces a weight function based on the coolant mass fraction to dynamically correct the turbulent viscosity to more accurately simulate the momentum exchange process in the mixing region. The simulation results of the modified model are compared with the film cooling effectiveness obtained by the pressure-sensitive paint technology. The investigated objects include smooth cutback surfaces and cutback surfaces with different rib structures. The mainstream Reynolds number is 10,000, and blowing ratios are 0.25, 0.50, and 0.75. The results show that the traditional SST model seriously overestimates the film cooling effectiveness, and the maximum prediction deviation exceeds 70%. The modified model improves the prediction ability of the decay trend along the flow direction and the low cooling effectiveness zone by adjusting the empirical parameters, and the maximum deviation from the experiment is within 5.3%. In this work, the fitting relationships between the empirical parameters and the blowing ratio and the prediction deviation when the empirical parameter is 1 are further established. The relationship shows good applicability under different rib structures and expansion conditions. By enhancing the turbulent viscosity and turbulent kinetic energy in the mixing zone, the modified model more accurately reflects the interaction mechanism between the mainstream and the coolant.