CFD Study For The Flow Field Between The Valve Core And The Valve Sleeve

The spool valve is used most frequently among all kinds of hydraulic valve. The spool valve has a mate clearance between the valve core and the valve sleeve and the characteristics of the inner flow field in the clearance can directly influence the valve's performance, especially for the cone valve which has a eccentricity between the central axes of the valve core and the valve sleeve.In this paper, the 2-D geometric model of the clearance which has different shapes is established according to the actual circumstances, and then it is imported into the Gambit which is the foreprocessor of the Fluent for generating 3-D geometric model and it's mesh. The hydraulic oil flow in the clearance between the valve core and the valve sleeve is simulated respectively when the valve core is static or moving.In the simulation study of radial force, the flow field of the clearance between the valve core and the valve sleeve is simulated under the different boundary conditions and with many different models .The models include the valve with cone or not, obverse valve or inverse valve, the valve with groove or not, eccentricity between the central axes of the valve core and the valve sleeve or not,ect. In the procedure of the simulation to the clearance flow field of the valve core with grooves, the adapt mesh is adopted, which the gradient of the pressure is designed to the adapt function. The adapt mesh is helpful to improving the precision. Furthermore, the calculated and simulated result of the lock force on the valve core are compared and analyzed.The leakage capacity of the clearance between the valve core and the valve sleeve is related to many factors. The flow field in the clearance between the valve core and the valve sleeve is simulated respectively when the valve core is static or moving and we can obtain the result of the leakage capacity according to the simulation. When the valve core is static, the flow field is simulated with models of the different length of the clearance,the distinct diameter of the valve core, diverse clearance dimension,disparate press drop and dynamic viscosity of the hydraulic oil under the different boundary conditions. When the valve core is moving, the flow field is simulated with models at different speed magnitude and direction under the different boundary conditions. Then the leakage capacity is calculated with formula. Furthermore, the calculated and simulated result are compared and analyzed.The leakage capacity of the established model under the paper's boundary conditions maybe is positive or negative.Positive leakage capacity means the oil flux along the direction of pressure drop. Negative leakage capacity means the oil flux against the direction of pressure drop.Excessive leakage capacity not only bring energy loss but also influence well-balanced work and speed of the organization. Therefore, studying the influence factors of the leakage capacity and summarizing the rule are helpful to the valve design and analysis.The study for the valve has offered the significant reference to designing the valve and optimizing the performance.The project is the study content of the National Natural Science Foundation of China "Improving and application study on flow force's compensating methods and calculating formula of the hydraulic valve". Foundation program number: 50675147.