关键词: 可调推力火箭发动机;发动机控制系统;电液伺服阀;自激振荡

Abstract: During the performance tests of a variable thrust engine,severe vibration occu rs to the electrohudraulic servovalve, which makes the thrust ratio decreased .Through analysis it is found that the vibration of the electrokydraulic servovalve is caused by the trasient-flow forces due to negative damping. If the viscous damping factor ξa is less than the negative damping factor ξ1,i. e. ξa-ξ1<0, the valve will vibrate; otherwise,(ξa-ξ1>0), the valve will not vibrate. In order to enssure the valve operating stability, the structure of the valve has been changed to keep ξa-ξ1>0. In this case, the electrohydraulic servovalve doesn’t vibrate any more during performance tests.

Key words: Controllable thrust rocke t engine;Engine control system;Electro-hydraulic servovalve;Self-Oscillation