Combustion Characteristics of Ethanol/Liquid-Oxygen Rocket-Engine Combustor with Planar Pintle Injector

Abstract

The pintle injector is a promising candidate for propellant-injection systems for various rocket engines. However, fundamental studies focusing on the pintle injector are rather limited, and the effects of key design parameters on combustion behaviors of the injector are still not identified. Therefore, combustion tests of an ethanol/liquid-oxygen rocket-engine combustor with a planar pintle injector are conducted to investigate the effects of total momentum ratio and on the combustion characteristics of the pintle injector. The total momentum ratio and vary from 1.0 to 2.2 and from 0.32 to 3.65, respectively, whereas the combustion pressure is kept constant at approximately 0.4 MPa. The spray structures are observed with high-speed cameras. The characteristic exhaust velocity () efficiency increases with the increase in in the fuel-centered configuration, and the opposite tendency is observed in the oxidizer-centered configuration. The efficiency decreases with the increase in the total momentum ratio due to the impingement of propellant droplets on the combustor wall. The effect of the total momentum ratio on the efficiency is larger in the oxidizer-centered configuration than that in the fuel-centered configuration due to the difference in the amount of the impinging propellant. The atomization characteristics are improved as the propellant-injection velocity increases, which results in the high efficiency.