Model for Fuel Droplet Evaporation in Combustion Chamber of Liquid Propellant Rocket Engines

Abstract

Complete burning of liquid propellants droplets is very important to avoid combustion instability and to get higher specific impulse from liquid rocket engines. Combustion takes place in gaseous phase and reaction is fast. So, the time consumed by a droplet for complete burning is the time taken by a droplet to get evaporated. An analytical mono component fuel droplet evaporation model is developed and proposed for droplet evaporation in liquid rocket engine based on heat and mass transfer. Effect of the fuel droplet curvature on vapor pressure is incorporated in the model. The model is applied on a small-scale combustion chamber of bi-propellant liquid rocket engine where fuel concentration away from droplet is not zero. A code is generated and applied. The results of the model show that fuel droplet diameter, combustion chamber pressure, chamber diameter, mass flow rate and droplet relative velocity with hot gas has significant effects on the life of droplet and characteristic length. Effects of chamber pressure and diameter are more significant for larger droplet size.