Experimental investigation of self-pressurized propellant injection into a simulated rocket motor combustion chamber

Abstract

Behaviour of self-pressurized nitrous oxide (N2O) injection through a sharp-edged channel intended to replicate a rocket motor injector has been studied using carbon dioxide (CO2) as an analog fluid. Experimental data was collected from 14 separate experiments which varied pressure upstream and downstream of the injection channel. The experimental data was used to determine the accuracy of previously developed two-phase flow models found in the literature, including the homogeneous relaxation model (HRM), the homogeneous equilibrium model (HEM), and the delayed equilibrium model (DEM). The HRM was determined to be the best model for predicting flashing water flows, but it required adjustment of its vapourization rate equations to properly represent the CO2 flashing flows. A genetic algorithm was used to fit the HRM vapourization rate coefficients to the experimentally measured mass flow rate and pressure distribution. The modified HRM model developed in this work has been used to show a relationship between mass flow rate and injector geometry for a range of operating conditions relevant to rocket motor applications.