Abstract: In order to analyze the fluid force in the pilot stage of jet deflector servo valve, an orifice model based on the rectangular nozzle and receiver of jet plate in pilot stage is established, and a simplified formula of fluid force is obtained. From the perspective of jet flow field, a two-dimensional internal flow field model of jet deflector pilot stage is established. And the momentum theorem method and the differential pressure method are presented to calculate the steady-state fluid force based on the simulated discrete data. An automatic test system for measuring the fluid force in pilot stage is designed. The results show that the calculated results based on simulated discrete data are basically consistent with the theoretically calculated and experimental results.

Key words: fluid drive and control, jet deflector servo valve, pilot stage fluid force, orifice model, flow field simulation, test system