| The mining dump truck is widely used in large mines,but because of its heavy load and self weight and poor driving conditions,its riding comfort and handling stability are poor.The hydro-pneumatic suspension transmits all the force and torque between the wheels and the frame as the only part connecting the dump truck’s wheels and frame.Therefore the mechanical property of the suspension is directly affect the dump truck’s riding comfort and handling stability.So it is necessary to study the mechanical characteristics of the hydro-pneumatic suspension.The object of this article is the hydro-pneumatic where the oil and gas directly contact.It has a complex mechanical property and the physical characteristics of oil and gas are changeable.The traditional mathematical model of hydro-pneumatic suspension can not reflect the flow details of the fluid in the oil and gas suspension,and can not guide the optimal design of the hydro-pneumatic suspension structure accurately.Therefore,using the numerical simulation of two-phase flow field,which can reflect the details of fluid flow,and the CLSVOF method was improved to make it possible to consider the change of fluid properties,to simulate the internal flow field of the hydro-pneumatic suspension on the basis of considering the change of the fluid properties.And the mechanics properties of the hydro-pneumatic two-phase flow can be accurately studied.In addition,the hydro-pneumatic suspension structure with good mechanical performance was designed based on the riding comfort of the mining dump truck.The main contents of this paper include:1.The gas and oil physical properties change was considered while establishing the thermodynamic model of hydro-pneumatic suspension.Dump truck weight and carrying capacity is heavy,and hydro-pneumatic suspension’s internal pressure can reach to tens of Mpa,then the gas dissolution phenomenon was appeared.Considering the gas dissolved and using the real gas state equation to establish the hydro pneumatic suspension stiffness force mathematical model;considering the oil viscosity temperature characteristics the hydro pneumatic suspension damping force model was established;then temperature’s influence to the hydro pneumatic suspension’s rigidity and damping force can be simulated.Based on the analysis of heat transfer process of hydro pneumatic suspension system,the thermodynamic modeling was established,then oil and gas’s balance temperature were predicted.An accurate temperature environment and physical parameters was provided for the subsequent suspension’s two-phase flow simulation.2.The CLSVOF method and the VOF method are used to simulate the two-phase flow of the hydro-pneumatic suspension,and chose the method with high accuracy as the numerical simulation method of the two-phase flow of the hydro-pneumatic suspension.the CLSVOF method’s principle and key steps was analyzed;and the two method were all used to simulate the two-phase flow of the hydro-pneumatic.And on this basis,the hydraulic suspension platform was established,then based on the experimental data of the upper and lower fulcrums of the hydro-pneumatic suspension which were monitored during the vehicle’s riding comfort test,the simulation results are validated and analyzed.The accuracy of the two methods is verified by the CLSVOF method,and the accuracy of the numerical simulation of the two-phase flow of the oil-air suspension is verified.3.The CLSVOF method is improved and the source term is added to its continuity equation to calculate the mass transfer between the oil and the gas caused by the gas solubility when the numerical simulation of hydro-pneumatic suspension two-phase flow is carried out.The flow pattern of oil and gas suspension was analyzed in detail,and the oil-gas suspension is not only the wave-like oscillation,but also has the mass transfer caused by gas dissolution between the phase and the phase.The CLSVOF method is improved and in the form of UDF to add the source term in the CLSVOF method.So that the simulation of the quality transfer between oil and gas could be calculated.And the numerical simulation of the two-phase flow of hydro-pneumatic suspension is carried out.The accuracy of the improved CLSOVF model is verified by using hydraulic platform of the hydro-pneumatic suspension.4.Based on the numerical simulation of two-phase flow of hydro-pneumatic suspension,the structure of hydro-pneumatic suspension is optimized.the parameters that have a great influence on the mechanical properties,such as the height of the gas,the cross-sectional area of the cavity,the flow coefficient of the valve system is considered as the optimization variables,than the vehicle ride comfort was optimized Based on the two-phase flow method,the relationship between the detail structure and the flow coefficient is studied.The optimal structure of the structure of the valve system was optimized by the final optimization result. |
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