Research on the cavitation in the pilot stage of flapper-nozzle hydraulic servovalve with fluid-structure interaction

The fluid-solid interaction phenomenon in the pilot stage of flapper-nozzle servo valve and armature assembly structural stress field is the main reason of self-excited noise and instability. The cavitation phenomenon is the main source of servo valve noise and cavitation erosion. In order to study the mechanism of transient cavitation in the pilot stage of flapper-nozzle servo valve, the three-dimensional model, ICEM CFD software was used for meshing, star-ccm+ simulation software was used to simulate the cavitation and flapper movement characteristics in the flow field under the pilot stage fluid-structure interaction dynamic characteristics of the servo valve. The results show that the fluid-solid interaction of the flow field in the flapper-nozzle pilot valve can cause the periodic change of cavitation in the flow field, and the increase of inlet pressure at the nozzle and the movement of the flapper will aggravate the cavitation phenomenon. The conclusions in this paper can provide theoretical basis for the stability of servo valve and the prevention of cavitation.