Investigation on the Influence of Film Cooling Structure on the Flow and Heat Transfer Characteristics of Axisymmetric Plug Nozzle

Some numerical simulations were used to study the effects of blowing ratio (0.25-0.5), hole diameters(0.65 similar to 1 mm), and hole inclination angle (30 similar to 60 degrees) of the film cooling structure on the cooling and aerodynamic characteristics of the axisymmetric plug nozzle under the condition of transonic. The results showed that the bow shocks appear near the film holes on the plug wall in the supersonic region, which cause the wall cooling effectiveness of the plug to decrease. Compared with the baseline plug, the blowing ratio ranged from 0.25 to 0.5, the wall average temperature of the rear plug decreased by 34.4 similar to 48.1%, the thrust coefficient and total pressure recovery coefficient decreased by 0.31 similar to 0.61% and 0.52 similar to 0.93%, respectively. When the perforated percentage is constant, the wall cooling effectiveness increases with the decrease of the hole diameters. The increase in the inclination angle of the film holes lead to the decrease in cooling effectiveness and aerodynamic performance. This is because the penetration ability of the cooling air to the mainstream is enhanced, and the obstruction to the mainstream boundary layer is increased, resulting in the increase of bow shock intensity near the film holes in the supersonic region.