N₂O Flow History Prediction in an Oxidizer Feed Line of Hybrid Rockets

Abstract

Nitrous oxide is in a gas-liquid equilibrium state at room temperature, and its vapor pressure is very useful concerning devices such as a pressure-fed hybrid rocket engine systems. However, it is not easy to estimate the flow history of the equilibrium flow. The vapor pressure and the latent heat of the vaporization of nitrous oxide strongly depend on its temperature. Though many models have been proposed, we used a simple equilibrium model and examined important parameters and negligible parameters considering experimental results. Experimental results displayed a substantial difference between the top and bottom tank temperatures, and that the tank pressure greatly matched the saturated vapor pressure at the liquid-phase temperature. A simple analysis showed that the determination of initial temperature was the most important factor and the heat transfer from the tank wall to the nitrous oxide was negligible.