Development of Non-Combustible Rocket Engine by Using Explosive Boiling of Liquid Nitrogen

Abstract

Recently, the activity of the development of a small rocket in universities has been enhancing. Focusing on safety, we have been developing a small rocket engine using two liquids (LN₂ and H₂O) without combustion process. In order to improve reliability and performance of this engine, we developed the engine without a valve in a LN₂ passage. In this engine system, initial water temperature and GN₂ pressure were changed within the ranges of 100-170°C and 1.0-2.0 MPa for reducing weight of water and getting higher performance. Thrust was increased with increasing the initial water temperature because the flow rate of H₂O was decreased with increasing the water temperature. In addition, thrust was increased with decreasing the GN₂ pressure under these experimental conditions. As a result, the ratio of LN₂ and H₂O weight could be reduced from 3:4 to 1:1. The relation between the mixing chamber pressure and an initial water temperature was very important for reducing of amount of fuel.