Numerical Investigation Of The Cavitation Damage In The Wet Cylinder Liner Of Heavy-duty Diesel Engine

With the continuous tightening of environmental fuel consumption regulations and the increasing competition in the market,efforts to develop clean,efficient and highly reliable internal combustion engine products have become the mainstream of the industry’s technological development.However,in the development process of clean and efficient internal combustion engine products,especially in the development and trial production of high-power density internal combustion engines,the phenomenon of cylinder liner cavitation failure has increased and aggravated,and even some diesel engines showed significant cavitation failure in a short-term bench test.This article focuses on the cavitation difference between a certain heavy-duty diesel engine before and after the explosion pressure is increased,proposing a coupling modeling method that integrates cylinder liner vibration deformation and coolant cavitation.First,based on the piston-cylinder liner transient dynamics model,the modal analysis of the cylinder liner is carried out,and the wall dynamic response of the cylinder liner under the side impact of the piston was obtained by simulation,which was verified by the bench test,and the two diesel engines were compared.The difference between the vibration characteristics of the cylinder liner and the correlation between the vibration characteristics of the cylinder liner and its constrained mode are proved.The vibration signal obtained by the simulation is input into the flow field in the form of a dynamic grid,and the pressure fluctuation and gas volume fraction change in the different water cavity regions of the two diesel engines under the excitation of the cylinder liner vibration are compared and analyzed.The study shows the cavitation of the flow field near the cylinder liner.The characteristics are obviously different in the regional distribution.The cavitation intensity is mainly affected by the lowest pressure in the flow field and the cumulative time under negative pressure.In addition,the cavitation intensity is not linearly related to the vibration amplitude of the cylinder liner wall,but is related to the vibration frequency and mode.There is a coupling correlation between the mode shapes.Generally speaking,the cavitation characteristics of the main thrust side of the high explosion pressure diesel engine are more significant.In order to study the influence of various boundary conditions on cavitation,starting from the characteristics of vibration and flow field,numerical simulation of the cavitation fluctuation of flow field under different working conditions is carried out,The influences of cylinder liner vibration characteristics(amplitude and frequency),cooling water chamber thickness,steady-state pressure of flow field and cooling water temperature on cavitation are summarized.The cavitation fluctuation of the flow field increases with the increase of the vibration frequency and amplitude of the cylinder liner,and the vibration frequency has a more significant effect on the cavitation tendency.With the increase of cooling water chamber thickness and cooling water temperature,the cavitation fluctuation of the flow field is weakened,and the cavitation corrosion tendency is reduced.With the increase of the steady pressure,the cavitation fluctuation of the flow field increases obviously,and the cavitation tendency increases.The cavitation simulation method proposed in this paper can effectively analyze the main factors that cause cylinder liner cavitation,and provide an analysis basis for the prediction of cylinder liner cavitation tendency and dangerous area.These research results are for the analysis of cylinder liner cavitation tendency.Forecast research provides new ideas and methods.