The Signal Characteristics Finite Element Analysis Of Rotating Valve Type Drilling Fluid Continuous Pressure Wave Signal Generator

In the way of MWD information transmission, fluid pressure pulse transmission mode iscurrently the most common use of signal transmission way, among them,The transmissionrate of continuous pressure wave signal transmission mode is the highest, its core componentis a continuous pressure wave signal generator. along with the increase in downholemeasurement parameters, the borehole information transfer rate is urgently needed to behigher in the process of drilling, so it is necessary to carry out systemic basic research aboutcontinuous pressure wave signal generator.In this paper, according to the theory of unsteady flow of fluid mechanics, analyze themechanism of drilling fluid pressure wave, establishe mathematical model of continuouspressure wave through drilling fluid Bernoulli equation of vertical drill string system; usingthe FLUENT software to simulate the drilling fluid flow field and the dynamic stress field ofthe continuous pressure wave signal generator, simulate and analysis the pressure waveformand frequency spectrum characteristics of signals. through the research of rotation torque ofthe rotary valve, simulate and analysis the axial force and fluid driving torque of the rotor ofrotary valve, provide research foundation for the rotor of the rotary valve drive and control.Theoretical studies have shown that, rotary valve pressure signal contens water hammerpressure the rotor disc block drilling fluid flow, drilling fluid pressure loss caused by valvethrottling hole and pressure loss of fluid motion inertia; in the condition of the stator and rotordisc has certain fluid leakage channel, drilling fluid pressure change in the rotary valve, waterhammer pressure plays a main role, throttling pressure loss and pressure loss of fluid inertiaon relatively minor auxiliary function, the theory analysis result was verified by the FLUENTsoftware simulation. the simulation analysis shows that, Drilling fluid pressure signal strengthis related to viscosity of drilling fluid, drilling fluid flow, clearance between rotor and stator,the thickness of the stator and rotor, signal strength increases with the increase of the drilling fluid viscosity and flow rate, decreases with the increase of the gap between rotor and statorand stator thickness.Studies have shown that, rotary valve resistance moment contents fluid friction torquecaused by rotor axial force acting on thrust bearing and fluid drive torque, the friction torquevaries with the rotor rotation angle is nonlinear; fluid drive torque shows cyclical change withthe rotor rotation angle, its intensity is related to the thickness of the rotor blade, its effect onthe rotor rotation alternates between blocking and promoting role with the corner andincreases with the increase of the rotor blade thickness.