Numerical Stimulation Of Formation Dynamics Tester (FDT) Throttle Control Valve

Cable formation tester is a testing equipment in well. It is landed by specially electrical cable. Throttle control valve is a two-position two-way valve which is applied to regulate mass flow rate and pressure in sample module system of formation dynamics tester.The throttle valve is high accuracy valve compared by others. It is important that throttle valve control fluid pressure. This determine whether collecting the original fluid of formation. The throttle valve’s effectively regulating formation fluid sample depends on hydraulic performance of valve cavity. At the same time, throttle chamber’s flow field charac-ter and valve core’s force when valve rod displace up and down are not ignored during designing or application. So far, Therefore, flow field characteristic of throttle control valve is not studied in cable formation tester.the paper is about throttle numeric simulation of valve and study of valve cavity’s flow field structure, valve core’s force in dynamics and static state.The paper design throttle valve according to sample module system parameter of formation dynamics tester, build valve cavity three-dimensional geometric model with CAD software-UG, mesh model with GAMBIT. By selecting classic SIMPLE algorism based on pressure amendment and the standard k-ε mode, valve cavity’s flow field structure, flow rate character valve core’s force in dynamics and static state is numerical simulated and researched for optimizing physical structure design of throttle valve.Valve cavity’s flow field distribution is distinctly depicted by numerical simulation. Pressure distribution of valve cavity apparently declines in cherry. low pressure spot appearance in gap between valve core and valve seat, the minimum pressure reach to2.5MPa. Pressure distribution is relatively high far away cherry. In conductor line, pressure becomes low alone radial direction, indistinctly changes alone axial direction.Jetting angle in velocity field is studied. Velocity vector express that cherry is becoming grow, jetting angle decrease, velocity absolute magnitude reducing. Energy dissipation of fliud is in neighbouring cherry. When pressure ascent and aperture become increasing, flow rate is increasing. Energy dissipation is positive correlation with drop of pressure in definite aperture. flow coefficient only depend on aperture and structure, not differential pressure. Flow rate characteristic curve is drawed by numerical simulation. Flow rate characteristic belong to quick opening flow characteristic.Structure of the throttle valve is modified according to above numerical simulation. Secondly stimulating anlaysis show the flowing three:Firstly, distribution of flow field is becoming even, turbulence area nearly disappearance. Separation extent of fluid and wall decrease, main flow can displace closely along cavity channel. Thirdly, local resistance, energy dissipation have reduced by30%, flow coefficient have rised by25%.Valve core’s force is analyzed with movement grid. In calculation of valve core’s force in static state, the valve core’s force is respectively computed and compared by means of theory calculate and numeric stimulating. result of numeric stimulating is receivable, error is under5%. Valve core’s stable force decrease with throttle valve aperture’s increasing. Direction of force is congruous with valve core closing. the force situation of valve core’s opening and closing is different. During opening, curve knee point of valve core’s force in dynamic state is comparable ahead of time, the value rise when move velocity of valve core increase. Value of valve core’s force fall from negative value range, then rise from positive value range when valve core is opening. Valve core’s force is grater, the value only fall from negative value range if move velocity of valve core is more than1mm/s; During closing, curve knee point of valve core’s force in dynamic state is comparable ahead of time, the value rise when move velocity of valve core increase. Value of valve core’s force only fall from positive value range. Valve core’s force is grater if move velocity of valve core is more comparable larger.Throttle chamber’s flow field character and valve core’s force are analyzed. This will provide theoretical basis and reference for optimizing physical design of throttle valve.