メインイメージ

Combustion in Liquid Rocket Engine

Introduction

Rocket engine is the only propulsion system for space transportation. Significant amount of time and cost is spent to develop high performance rocket engine. Energy conversion process in rocket engine combustor occurs under peculiar conditions such as high pressure over 100 atm and high temperature about 3000K. There are a lot of phenomena to be revealed for high performance, low cost, high reliability rocket engine.

Propellant Selection

Propellants selection in rocket engine is a very important because it determines almost all the performance of rocket.

One of the most high performance propellants today is the combination of liquid oxygen (LOX) and liquid hydrogen.Hydrogen can achieve high specific impulse and it also has good cooling performance. However, because specific gravity of hydrogen is very small propellant tank becomes large and heavy, and operating process tends to be complicated because of its low boiling points and that leads high operating cost.

Hydrocarbon fuels such as kerosene are attractive fuel because they have high density and they are easy to use, though their specific impulse and cooling performance is relatively low. However, combustion mechanism of hydrocarbon in rocket engine combustor is still unknown. Therefore, the fundamental combustion mechanism under high pressure and high temperature condition shoud be revealed.

H2Aロケット

An Example of Liquid Rocket :H2A Launch Vehicle (C)JAXA

Throttling Technology

The thrust control technology is one of the key technology for the future space tranportation system. Thrust control is crucial for Orbital Transfer Vehicles and landers of planet exploring vehicle because thurst should be changed in wide range in their missions. However, it is quite difficult for a rocket engine to reduce thrust without combustion instability and a lot of researches have been conducted to develop the combustion system which can acheive stable operation in wide range of thrust level.

We focus on propellant injection system and combustion dyanmic characteristics under thrust control. And we are also interested in the combustion phenomena under high pressre and temperature condition, therefore, we are developing new measument system to reveal the phenomena proceeding in the combustor.

Combustion Test System

The rectangular combustor with planar pintle injector and propellant feed system.
The propellant is Ethaol/LOX and a torch ignition system is used for the ignition.

teststand

The comobustor under hot condition

combustion