Study of Equivalence Ratio and Propellant Effects on a Reactive Flow with Low Residence Time and Highly Variable Tempereture and Pressure

Gas aerothermodynamics is the thermodynamics of a gas in high velocity associated with heat transfer. One of the devices which takes advantage of this field is a rocket system. High velocity flow filed with intensely varying pressure and temperature along the nozzle axis leads to reduction of residence time. This means the balance between chemical and flow time scales is changing in the flow stream. In this study, reacting flow composition variations in combustion chamber and nozzle of a liquid rocket engine is numerically investigated for hydrogen and kerosene fuels regarding combustion efficiency and performance of the engine. Numerical modeling has been conducted with the aid of commercial code FLUENT. k −e turbulence and EDC combustion models have been used to consider turbulence effects on the flow field. 9-step and 14-step skeletal mechanisms have been utilized to represent chemical oxidation of kerosene and hydrogen, respectively. Results show a reasonable accuracy in comparison with experimental measurements. As a result of this study, it can be concluded that in combustion chamber and convergent nozzle, the frozen and finite rate modeling have almost same results in all equivalence ratios. However, in divergent section of the nozzle some reactions proceed in finite rate regarding to fuel type. Finally, it can be noted that maximum Damkohler number occurs in the same axial position for both kerosene and hydrogen fuels.