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Abstract

Film cooling can be used as an effective method of cooling the thrust chamber wall of a liquid rocket engine. A coolant fluid, typically the propellant, is then pushed through the shaped holes until it ultimately reaches the thrust chamber wall. The thermal properties, most notably the effective conductivity, of the coolant and geometrical parameters provide an efficient cooling mechanism for the thrust chamber wall. Film cooling effectiveness is used to express the film cooling phenomena quantitatively. Concluding from the literatures, film cooling effectiveness mainly depends on certain factors such as blowing ratio, injection angle, compound angle/orientation, L/D ratio etc. The present study is related to the numerical investigation of different hole shapes for film cooling performance, which is widely used for cooling of high temperature in the thrust chamber walls, nozzle walls and gas turbines. The adiabatic film cooling effectiveness values are determined computationally, downstream of cooling holes. Different hole shapes compared are cylindrical holes, elliptic holes and semi-elliptic holes. Apart from hole shapes other parameters have been varied. Other parameters include blowing ratios and orientation of holes. The blowing ratio ranged from 0.67 to 1.33 while the orientation angles varied from 00 to 450. Results are presented for the centerline and laterally averaged adiabatic effectiveness, normalized temperature distribution, and velocity vector field. These results show the interactions between the mainstream hot gas and the cooling jets, and how those interactions affect surface adiabatic effectiveness. Out of all these cases, the best results have been computed for the semi-elliptic hole configuration. Semi-elliptic hole utilizes half of the mass flow as in other hole shapes and gives nominal values of effectiveness. The computed results were compared with the benchmark experimental data of Yuen et al. This comparison shows the results generated to be reasonable and physically meaningful.