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Numerical Study of Film Cooling in a Space Thruster

Madani, Mohammad Reza | 2019

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52869 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Mardani, Amir
  7. Abstract:
  8. In high-performance liquid fuel motors and space thrusters, the combustion chamber and nozzle walls are in contact with the gases caused by high temperature and pressure combustion, making severe thermal loads on the walls. Therefore, these systems require cooling mechanisms. The most common way of cooling in space thrusters is film cooling. This study is a numerical simulation of film cooling in the liquid fuel space thrusters. Numerical and empirical studies have been reviewed in this area and evaluated while conducting studies and results to select an appropriate model for ongoing project studies. Along this path, various fuel and oxidizing thrusters, including oxygen and hydrogen, kerosene and oxygen, methane, and oxygen, have been studied. However, the thrusters with propellants MMH and NTO have received particular attention. The cooling film is injected in gas and liquid states. Because of the combustion process, the chemical mechanism between MMH and NTO, as well as the modeling methods, have been investigated, and suitable detailed chemical mechanisms have been extracted. Current studies indicate that the efficiency of the cooling film, the inlet wall charge, the length of the cooling film, the temperature variations are important parameters. Of these, the heat flux to the wall and the wall temperature are of particular importance. The results of the simulation show that the dissociation reactions and the vaporization of the liquid film droplets have a significant effect on the heat flux reduction so that in the complete modeling setting (reactant liquid) and the nozzle throat, the highest heat flux enters the wall. This heat flux can be reduced by 40% by 15% fuel injection and 48% by 20%. A comparison of the results of the quadratic modeling level for the cooled film shows that none of the physics is negligible for simplification. Furthermore, for the study of heat transfer, this thruster must be considered the most complete (liquid injection with chemical reactions) to reveal the effects of evaporation and molecular decomposition
  9. Keywords:
  10. Heat Flux ; Thruster ; Film Cooling ; Liquid Fuel Engine ; Pulsed Plasma Thruster

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