Liquid-solid-thermal Coupling Analysis And Flow Visualization Of The Cartridge Poppet Valve

The social demand is the powerful engine for the technology. Hydrauliccartridge valve is the product of the rapid development of hydraulic technology,which requires higher pressure, larger capacity but smaller size, lighter weight,higher precision and efficient. Two-way cartridge valve raise the hydraulictechnology to a new stage. In some applications, the cartridge valve is the onlyoption for improving the productivity and competitiveness.The basic research problem includes the flow rate characteristics, flowforce and its influence for the static and dynamic characteristics, visualization offlow fields. The key for higher performance of the hydraulic valve is also tofocus on those fields. The poppet cone is the main structure form of cartridgevalve. The existing theory for poppet valve needs to be further studied toimprove.The cross section area is the key of the calculation of the flow rate. Theexisting theory about the cross section area has some problems. It exist theinaccurate that the area formula derived through the full cone poppet valve isadopted for the truncated valve and the cone-seated valve. Based on thedefinition of the cross section, its position varied the cone at the differentopening is identified when the cone moves over the large stroke through CFD visualization of flow fields. It shows that the traditional formula can be adoptedfor the cone moving over the small stroke, but is inadequacy for the conemoving over the large stroke. The divergence flow is very different from theconvergence flow. The formulas for the critical opening and the cross sectionarea are derived. It is found that the cone diversion is the main factor for thedifference of the flow characteristics in the convergence and divergence flow.The anti-cavitation ability of the orifice is an important index of the throttlingperformance. As the judgment standard of the cavitation inception has not yetunified, the pressure-recovery factor is defined for indicating the anti-cavitationability of the orifice through tracing back to the root of the cavitation.The flow force is the important factors to be considered in the design ofhydraulic valve, and closely ties the static and dynamic characteristics of valve.The flow force formula is one of the important basic equation for modeling thehydraulic system, has a great influence on the system characteristics. As a resultof the change of the cross section at the large opening, the traditional theoreticalformula of flow force is uncertain. The change of the pressure distribution alongthe cone is the nature of the flow force. The flow force can be calculated by theintegral of pressure along the cone obtained from analyzing the flow field. Thisis the most direct way. Based on the principles for selection of control volume,combined the main factor of flow rate, the selection of control volume varieswith the different orifice and the divergence and convergence flow condition.The corresponding calculation formula is derived by the theorem of momentum,so the characteristic of the flow force is obtained at full stroke.From the traditional formula of flow force, it can be found that the flow force is proportional to differential pressure, independent of the value of outletand inlet pressure. On the condition of equal differential pressure, the flow statebecomes the two-phase flow when the pressure is low, so the traditional formulaneeds to be amended. The critical pressure is put forward to distinguish betweenthe different flow stations. The three-dimension flow in the valve is simulatedby using full cavitaion model. The formula of the flow force is amended basedon the difference of the flow station made clear by analyzing the flow field. It isverified by existing experimental data.The hydraulic technology is widely used in the industrial control field,including some high-tech. In order to achieve more precise control, theperformance of control elements will be more demanding. The deformation ofthe sleeve and valve cone maybe has influence on the cross section area and fitclearance between them. Therefore, for the constant perfection at designing ofvalve, it is need to be considered when studying of cartridge valve flowcharacteristics. In this paper, the three-dimensional model of the integratedcartridge valve is established, consisting of the sleeve, the cone, the seat and theflow field. The liquid-solid-thermal coupling simulation is carried out. Thetemperature distribution of the solid and the flow field is showed. It is alsoobtained the deformation of the sleeve and the cone under the action of thethermal stress and fluid pressure. The conclusion is that the deformation of thesleeve and cone has influence on the clearance between them varied with thework condition. But the influence for the flow characteristics is negligible. Theliquid-solid-thermal coupling analysis for the whole valve has importantpractical significant. Finally, the test-bed for the flow characteristic and the dynamiccharacteristic of cartridge valve is built. To verify the formula of the crosssection area, the flow characteristics of valve at different opening anddifferential pressure is tested. Integrated into the formula of flow force and crosssection area, the AMEsim simulation model is established. The step response ofvalve is simulated. The step response of valve is tested at the different stepsignal valve. Comparing the simulation results to test results, it shows that thecomputational fluid dynamic formula provided by this paper provides the resultis credible.The above research results are to further improve the basic theory ofhydraulic valve. Formulas of cross section area and flow force are given even.The characteristic of valve can be studied even if cone moves at large stroke. Itsupplies theory basis for the non-linear modeling of hydraulic valve and hasengineering practical value.