Research On Structure Optimization And Erosion Characteristics Of The Rotary Valve For A High-speed Continuous Wave Pulser While Drilling

Continuous wave pulse generator plays an important role in producing high quality pulse signal in MWD system,so it is very important to optimize the structure of rotary valve.Based on the study of the generation and transmission mechanism of continuous wave pulse,the structure of rectangular rotary valve of continuous wave pulse generator is optimized to produce high-quality pulse signal.1)The generation mechanism of continuous wave mud pulse signal is described in detail,and the influencing factors and attenuation reasons in the process of signal transmission are analyzed.It is concluded that pulse signal should have sine wave characteristics to realize high-speed transmission in drilling process.2)According to the evaluation index of correlation coefficient between actual continuous wave pulse signal and standard sine wave and the functional relationship between valve port pressure difference and flow area,the polar coordinate equation of rectangular valve body notch is established.By analyzing the flow area variation law during rotor rotation,the ordinary rectangular semicircle linear valve port is optimized to rectangular semicircle arc fillet valve port,and the optimized valve port can produce high correlation coefficient 9998 sine pulse signal.3)Based on the analysis of the overall characteristics of the rotary valve,the threedimensional model of the rotary valve is drawn by using PROE,and the flow field simulation is carried out according to fluent.The variation rules of the pressure difference between the front and back of the valve port and the resistance torque of the rotor are obtained under the condition of different clearance between the stator and the rotor at the constant speed,which verifies the rationality of the designed rotary valve.The performance of the designed rotary valve is tested by the ground hydraulic circulation experiment.The rotary valve can produce good pressure waveform in practical work.4)Based on ANSYS finite element method,the computational fluid dynamics model of continuous wave generator rotary valve was established,and a series of threedimensional flow field simulation experiments were carried out.The influence rules of drilling fluid density,viscosity,particle diameter and particle mass flow rate on rotary valve erosion were analyzed.