Study of jet flow with vortex and pressure oscillations between the flapper - nozzle in a hydraulic servo-valve

This study is aiming to understand the jet flow behavior in the pilot stage of a flapper-nozzle hydraulic servo-valve and to study the characteristics between the flow field distribution and the inlet velocity. After the construction and working principle of the hydraulic servo-valve are introduced, the mathematical models for the flow field simulation based on standard k-ε model for turbulent flow are built. Velocity and pressure distributions of jet flow in both x-y and x-z planes are simulated at different inlet velocity and different size of the geometric model. The simulation results show the flow field distribution, variation of the vortex and pressure oscillations inside the jet flow field with the increase of inlet velocity. Theoretical basis is provided for the control of self-excited noise in a hydraulic servo-valve and better design of the flapper-nozzle pilot stage.