Modeling of liquid propellant combustion chamber

Liquid propellants are fuels which do not require external supply of oxygen for combustion. These fuels are widely used for propulsion applications in oxygen rare environments (underwater, space). We had previously presented a model for solid propellant decomposition in a combustion chamber. In this study we extend the model for the case of combined solid and liquid propellant combustion. Sub-models relating to solid propellant combustion and outlet flow-rate in the present study are borrowed from the previous study. The combustion chamber is assumed to be a ‘well-mixed reactor’. A model is developed to characterize the liquid propellant spray assuming the spray is a collection of individually burning droplets. A single droplet decomposition model was developed and used along-with the spray model to solve for the liquid propellant burning rate. Appropriate numerical methods and computer programs were developed to solve the model equations. The model predictions were compared with the experimental data obtained in earlier studies. Appropriate methodology for calibrating the model parameters was developed and its usefulness was demonstrated by comparing the simulated pressure profiles with the experimental pressure profiles. The presented model and results will be useful for selecting appropriate liquid propellants for propulsion systems and for the development of a system level model of propulsion systems.

• A simple model is presented for the simulation of liquid propellant spray combustion.
• The model was implemented and verified by comparing model predictions with the experiments. The model predictions agreed reasonably with the experiments.
• The model correctly captures the observed linear relationship between chamber pressure and liquid propellant flow rate.
• The model is shown to be useful to screen liquid propellant fuels with or without pre-mixed water.
• The model will be useful in design applications.