Cryogenic Throttle Valve Driven by BLDC Motor for Thrust Control of a Liquid Rocket Engine

This paper presents the activities performed for the development of a cryogenic throttle valve which was designed for the thrust control of an LRE. The throttle valve can adjust the flow rate of liquid oxygen under a cryogenic temperature of 90K and a high pressure of 113.2bar with the help of an electro-mechanical actuator driven by a BLDC motor. All development tests have been performed except engine firing test. The mathematical model and control algorithm of the throttle valve were described as a preliminary study on the design of thrust control algorithm for an LRE. The mathematical models of the throttle valve including a controller and a thrust control simulator have been developed. The dynamic characteristics predicted by the mathematical models showed good agreement with experimental results, thus proving the validity of the mathematical models. It was also found that an optimum control algorithm of the throttle valve for a thrust control simulator is an On-Off control.