Fluid Simulation And Reliability Sensitivity Analysis For Plunger And Barrel Assembly Of Fuel Injection Pump

As a precision component of diesel engine fuel injection system,the reliability of plunger and barrel assembly affects the working performance of the whole mechanism.Cavitation is one of the main failure modes of the plunger and barrel assembly of the inline fuel injection pump.Cavitation will peel off the material particles on the surface of the plunger,causing the plunger and barrel assembly to be stuck.Sometimes will also cause the diesel engine to run-away.Therefore,reliability anlysis and reliability sensitivity analysis of cavitation are important for imporving the reliability and durability of plunger and barrel assembly.The research work and achievements of this thesis are mainly summarized as follows:(1)The cavitation simulation model of Plunger and barrel assembly is established,and the cavitation mechanism of Plunger and barrel assembly is analyzed.Most of the existing research focuses on the cavitation of hydraulic machinery,as well as the lubrication performance and sealing performance of Plunger and barrel assemblys,while little attention is paid to the cavitation phenomenon and anti-cavitation performance of Plunger and barrel assemblys of diesel fuel injection pumps.Therefore,the thesis takes the above two points into account,analyzes the working principle of the Plunger and barrel assembly,and determines the serious cavitation movement process.Based on this process,the cavitation simulation analysis of the Plunger and barrel assembly is carried out.According to the velocity vector distribution map,the gas phase volume fraction map and the pressure contour distribution map,the location of cavitation occurrence in the plunger coupling is determined,and the mechanism of cavitation generation is analyzed(2)The reliability analysis method of Plunger and barrel assembly based on improved parallel strategy and Kriging surrogate model is established.In the thesis,cavitation is used as the failure criterion of Plunger and barrel assembly.Considering the influence of uncertain factors such as material parameters,structural parameters and external load of Plunger and barrel assembly,the reliability analysis method of Plunger and barrel assembly of diesel engine fuel injection pump is studied.Aiming at the computational efficiency of numerical simulation,the Kriging surrogate model is used to replace the complex reliability analysis model.Based on the idea of active learning and parallel computing,an improved parallel adding point strategy considering the position relationship of sample points is proposed.Based on the parallel strategy and Kriging surrogate model,the reliability analysis method of diesel engine fuel injection pump Plunger and barrel assembly is established,which improves the calculation accuracy and efficiency.(3)The reliability sensitivity analysis method of Plunger and barrel assembly based on parallel strategy and Kriging surrogate model is established.In the thesis,the reliability analysis model of Plunger and barrel assembly is combined with Sobol index method and Morris method respectively.Kriging model is used instead of numerical simulation to analyze the reliability sensitivity of Plunger and barrel assembly and quantitatively estimate the influence of input parameters on the reliability of Plunger and barrel assembly.In the structural design and improvement,the factors have a greater impact on the reliability of Plunger and barrel assembly should be focused to improve the durability and reliability of the Plunger and barrel assembly.