Abstract:For micro-small high-speed on-off valves, large flow and high-frequency response increase the flow force of the spool and affect its motion state. Therefore, analysis and compensation of the flow force are the key factors to improve the performance of the valve. To solve the problem that the traditional steady-state flow force theory calculation formula is not applicable due to the complex flow field structure of the ball valve high-speed on-off valve in high-frequency opening and closing state, the CFD method was used to study the flow force. Firstly, COMSOL software was utilized to establish the geometric model of the fluid field. Then, the pressure and streamline distribution diagram, flow curves, and steady-state flow force curves of the valve ball and spool under different valve openings were obtained by using the weakly compressible fluid and standard k-ε turbulence model and dynamic grid technology. Finally, to compensate for the reduced steady-state flow force, the valve port structure was optimized and the optimal parameters were determined according to the relationship between different valve port structure parameters and the force of the valve core, and the opening and closing time of the valve port. The results showed that the steady-state flow force of the valve ball in the oil inlet hole would decrease first and then increase with the opening of the valve port, but the steady-state flow force of the valve ball in the oil inlet hole was smaller than that of the valve ball in the oil return hole, so the steady-state flow force change on the spool was similar to that on the valve ball in the oil return hole. Reducing the diameter of the push rod and changing the flow channel into a gradually expanding flow channel could effectively compensate for the reduced steady-state flow force. Compared with the original structure, the opening and closing time of the improved optimal structure decreased from 1.047 ms to 0.714 ms, and the steady-state flow force compensation effect was obvious.