Liquid Fuel Film Cooling: a CFD Analysis With Hydrocarbon Fuel
Cooling of liquid rocket engine combustion chambers and nozzles is a critical component to liquid rocket engine design. The temperatures within the engine can exceed the melting temperature of the wall materials by such a large margin that generally two methods of cooling are required. A common one is regenerative cooling circulating fuel through the walls prior to injection into the combustion chamber. A second cooling method, often used in conjunction with regenerative cooling, is liquid fuel film cooling. Liquid fuel is injected along the surface of the wall to act as a barrier against the core combustion gases. A numerical model is developed for simulating liquid fuel film cooling in a rocket engine using a hydrocarbon fuel. The model incorporates turbulent multiphase flow with species transport using the commercial ANSYS R (c) Fluent CFD software. Conjugate heat transfer is simulated through walls containing embedded cooling channels. A novel User Defined Function is written to incorporate heterogeneous chemical reactions between the liquid fuel and the freestream gases. Comparisons are made between simulations with and without the heterogeneous reactions as well as with simplifications to the cooling channel geometry. It is found that simplifications to the cooling geometry can artificially reduce cooling performance while neglecting the heterogeneous reactions can artificially increase cooling performance.