| Hydraulic slide valve is not only the key comonent but also the main component for energy loss, so the property of slide valve is significant for hydraulic control system. For the sake of the stability of the hydraulic control system, the smaller adjustment grads of the hydraulic control valve is required in the domain of the construction machinery.So the spool with the round orifice is often used.But when the large flowrate passes through the slide valve,the spool is rotated, which shortens its life, makes the operability of the valve bad and affects the performance of the hydraulic control system. Therefore, analysing the rotating phenomenon of the slide valve has important actual significance to optimizing the stucture of the slide valve.In this thesis,the three-dimension CFD technique is used to simulate the flow field inside the hydraulic slide valve, and based on this, the author analyses the primary cause and the factor of the spool rotating.In this thesis, CFD software STAR-CD is used to establish the static model and transient model of the slide valve. After simulating the models of the slide valve, the velocity distribution, pressure distribution and the torque on the spool can be obtained. Based on the analyses of the velocity field and pressure field, with using the theory of fluid momentum, the author calculates and analyzes the torque on the spool of slide valve. The results showing that here are two primary cause of the spool rotating:in output part of the spool, there is dissymmetric flow because of the spout intervene; the flow channel out of the spool is dissymmetric. At the same time, when the spool position and spool angle are change, the influence on torque is analyzed in the thesis.At last, based on the aforesaid analyses, the author puts forward diminishing torque option,by appropriately modifying the structure of the slide valve. The thesis offers reference foundations with theapplied value for accurately optimizing of slide valves.
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