Numerical Simulation Of High Speed Hydraulic Cylinder Dynamic Process Flow Field Based On Dynamic Mesh Technology

With the development of high speed and high power in modern mechanical and electricalequipment, high speed hydraulic cylinder has already become the research focus. Currently, mostof researches on high speed hydraulic cylinder are about its control, cushion and sealing, but thestudy of its internal flow field is rare. According on the research of internal flow field of highspeed hydraulic cylinder, the rules of pressure distribution on the surface of piston during itsmovement are learned, it can not only understand the dynamic response characteristics of thehydraulic cylinder in order to control it better, but also can provide a useful reference andtheoretical guidance for the structure designs of sealing and buffer in high speed hydrauliccylinder.In view of this, a piston high speed hydraulic cylinder was taken as the object of study inthis article. Based on the computational fluid dynamics and numerical simulation theory, theflow field in hydraulic cylinder was simulated by using the professional fluid analysis softwareand dynamic mesh technique. Detail work was done in this paper as follows.(1) According to the structure of piston high speed hydraulic cylinder, the geometric modelwas established for simulation, and GAMBIT was used for its three-dimensional modeling andmeshing. Based on the discussion of flow state in the high speed hydraulic cylinder, the standardturbulent model was chosen for simulation. The application of dynamic mesh in the simulationof high-speed hydraulic cylinder moving boundary was achieved by UDF programming.(2) Under the specific work condition, the continuous dynamic simulation of flow field inhigh speed hydraulic cylinder was done by FLUENT, which combining with dynamic mesh. Thedistributions of path line and pressure of the flow field in high speed hydraulic cylinder havebeen analyzed. The transient curves of velocity and pressure have been obtained by extractingdata. The initial stage, uniform stage and termination phase of the movement of high speedhydraulic cylinder have been discussed in detail.(3) The high speed hydraulic cylinder with different pressure, stroke, the initial chamber, thesize and distribution of oil port have been simulated respectively. The influence of the dynamicsand structural parameters to the movement of high speed hydraulic cylinder was discussed. Theresults showed that: the greater the pressure differential, the faster do high speed hydrauliccylinder to get the stable phase, and the greater the piston velocity fluctuations. A shorterworking stroke makes the more stable starting of hydraulic cylinder. The bigger initial volumechambers, the faster do high speed hydraulic cylinder to get the stable phase. The smaller theinitial volume chamber is, the more stable the starting of high-speed hydraulic cylinder is. Thesmaller oil ports, the longer the fluctuation cycle of the speed of hydraulic cylinder, the greaterthe amplitude and the worse the stationary of hydraulic cylinder. The no bias oil portsdistribution is better than bias ports.