变推力发动机电液伺服阀振动问题分析与计算

THE ANALYSIS AND CALCULATION ON THE VIBRATION OF AN ELECTROHYDRAULIC SERVO VALVE FOR VARIABLE THRUST ENGINES

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

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

摘要:

变推力发动机的电液伺服阀在试车时曾出现过剧烈振动,造成推力比下降.经分析,我们认为,电液伺服阀的振动是由瞬态液动力诱发的负阻尼引起的.当时,阀就振动,当时,阀就不振.我们从结构上采取措施,使保证了阀的稳定性,在这个条件下,电液伺服阀在试车中,未出现振动.

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.