Research On The Mechanism Of Stable Discharge And Pressure Stabilization Of Drilling Pump With Airbag-Free Airbag And Optimization Of Structural Design

During oil drilling,the reciprocating movement of the drilling pump causes flow changes that cause pressure fluctuations in the discharge line.These pressure pulsation shocks will not only cause the structural vibration of the drilling pump,produce noise to worsen the working quality of the drilling pump,but also affect the service life of the drilling pump and the working accuracy of the system,and even damage the system pipeline or components,causing major accidents.This fluctuation cannot be eliminated by the piping system alone,so it is necessary to install an air package in the piping as a buffer device for pressure pulsation in the pipeline.Currently,airbag air packs are typically installed near the outlet of the drilling pump to attenuate pressure pulsations in the drilling system.However,the existing conventional airbag air bag maintenance is difficult,the life of wearing parts is short and the follow-up maintenance cost is high,especially under high pressure and large flow,the air bag inside the air bag is more likely to be damaged,resulting in its pressure stabilization effect is not very good.In order to solve these problems,this thesis studies the airbag-free airbag of QDP-2200five-cylinder drilling pump unit,carries out the theoretical study of flow and pressure fluctuation characteristics of drilling pump with crank linkage mechanism and the mechanism of stable discharge and pressure stabilization of airbag-free airbag,and conducts the overall design,fluid dynamics analysis,bidirectional fluid-structure interaction analysis,modal analysis and multi-objective structure optimization design of the airbag without airbag.The specific research contents mainly include:(1)Based on the crank connecting rod structure form and working condition data of QDP-2200 five-cylinder drilling pump,considering the volume loss in the actual work of the drilling pump,according to the movement law of the piston in the working cycle,the analysis of the instantaneous flow dynamic change law of the drilling pump was carried out,and the 1D simulation system of the QDP-2200 five-cylinder drilling pump system was built by using AMEsim software to explore the law of pressure fluctuation in the suction and discharge pipeline in a single cycle of the drilling pump.(2)Considering the stable discharge and stabilizing performance of airbag-free airbag and its influencing factors under the working condition of drilling pump,the mechanism of stable discharge and stabilization of airbag-free airbag was explored by applying hydraulic fluid dynamics and its electro-hydraulic comparison.By using the kinetic method,the drilling pump-air package-pipeline is studied as the same system model,and the dynamic equations of liquid flow at different positions inside the air package are obtained.The evaluation index of the working efficiency of the air package was proposed,the influencing factors of the flow pulsation of the air package were analyzed,and the influence of the structural parameters of the air package on the flow pulsation attenuation rate was analyzed.(3)Drawing on the traditional airbag design method,the airbag-free airbag volume and shell inner diameter calculation was carried out,the dimensional parameters of the airbag-free airbag inlet and outlet were determined,and the airbag-free airbag shell wall thickness was determined,taking into account the requirements of the airbag-free airbag steady discharge and pressure stabilization characteristics;then a three-dimensional model of the airbag-free airbag was established using Solid Works software.(4)Based on the theory of computational fluid dynamics,the mathematical model of the internal flow field of the airbag without air bag was constructed by using the hydrodynamic equation and the turbulence model control equation.Using Fluent simulation software,a finite element simulation model of the internal flow field of the airbag-free airbag was established,and the pressure and velocity distribution laws of the internal flow field of the airbag-free airbag were analyzed,and the stable pressure performance of the airbag-free airbag was preliminarily verified.Bidirectional fluid-structure interaction simulation is carried out to obtain the equivalent force strain cloud of the air packet during operation,and the modal analysis results considering bidirectional fluid-structure interaction pressures and no pressures are compared.(5)Parametric modeling of airbag-free air bags,first theoretical analysis of the data of each group of air bags,and then simulation analysis of pressure fluctuations and flow fluctuations of air bags by using fluid dynamics,combined with sensitivity analysis,and then selecting the optimal parameters for optimal design.A method based on the response surface method-intelligent optimization algorithm is proposed to optimize the structure of the air packet,and a response surface model is established with the optimal parameters obtained after sensitivity analysis as the design variable,the structural size as the constraint,and the minimum pressure fluctuation and the minimum flow fluctuation as the goal.Then,the improved intelligent optimization algorithm is used to carry out multi-objective solution to obtain the Pareto frontier solution set of airbag-free air pack,and the results show that the optimized air package improves the performance of the drilling pump and achieves the purpose of reducing pressure fluctuation and flow fluctuation,which provides a reference for future air bag research.