In order to analyze the characteristic of high jet pressure of jet pipe nozzle in the jet pipe servo valve

a pre-stage jet pipe servo valve mathematical model was established to get the impact of the jet pipe deflection displacement

the radius of jet pipe nozzle and the radius of receiving hole on its internal fluid pressure

nozzle exiting velocity and recovery pressure in the left and the right holes of receiver. Flow field analysis found that vortex was prone to occur at high velocity jet exit

and there existed annular negative pressure effect. The results showed that:under high jet pressure

when the radius of jet pipe nozzle increased

the recovery pressure increased

and when the radius of receiving hole increased

the recovery pressure decreased. The best internal value of the ratio of the radius of receiving hole to the radius of the jet pipe nozzle was[1.3

1.5]. When jet pipe deflection displacement increased

on the side of displacement increase

the effective recieving area between the jet pipe and the receiving hole increased

but the vortex between the jet pipe and the receiving hole expanded and the annular negative pressure effect of the internal flow field increased

and the recovery pressure of the receiving hole decreased.