Numerical study on film cooling characteristics of two-dimensional convergent divergent nozzle based on the source term method

In turbofan engine exhaust systems, film cooling is used to prevent excessive temperatures and improve infrared stealth. However, CFD simulations of film cooling are often impractical due to high computational costs, limiting rapid and accurate prediction of infrared, flow, and heat transfer characteristics during cooling design. This study introduces a novel source term method to efficiently simulate the flow and heat transfer behavior of discrete film cooling holes. The method applies mass, momentum, energy, and species fluxes as source terms at the cooling hole inlets and outlets, overcoming the high computational demands of traditional CFD. By incorporating a multidimensional database of discharge coefficients and coolant penetration depths under various flow conditions, the approach significantly boosts computational efficiency while maintaining accuracy. Validation shows that the method predicts cooling efficiency with errors under 6 % compared to CFD for mainstream Mach numbers from 0.3 to 1.2. It also considers factors such as boundary layer suction, solid heat conduction, and coolant penetration, enhancing the fidelity of both discharge coefficient and heat transfer predictions. Applied to different nozzle components, the method demonstrates that film cooling can reduce infrared radiation intensity by up to 42.13 % in the 3–5 μm band and 19.59 % in the 8–14 μm band, with the divergent section achieving the most effective cooling by reducing wall temperatures by up to 115 K.