Analysis Of Factors Affecting Thermal Load Of Diesel Engine’s Key Components

During the working process of the diesel engine,due to various loads,the working condition of some important parts is very bad.Among them,the cylinder head,cylinder liner and piston directly bear the action of high temperature and high pressure gas.The reliability of these parts is closely related to the reliability of the whole machine.Related.Based on the development of the key heated components of a marine diesel engine,this paper conducts a thermal-mechanical stress coupling analysis under fluid-solid coupling,and explores how the high-cycle fatigue of these components meets the conditions of use under the stress and fatigue strength.Lowering the heat load is the focus of research.This paper uses numerical simulation as a means to explore the influence of different parameters on the thermal load of key heated components by changing various single factors while ensuring the power,and analyze the sensitivity of different factors to the thermal load and safety factor of each component.Proposing a parameter optimization scheme provides a reference for more effective control of the thermal load of important components of a high-strength diesel engine in the future,which is of great significance.The main contents of this paper are as follows:(1)Based on the multi-physics model,the CFD model of the integrated cooling water chamber of the block-cylinder-cylinder head,the temperature and stress field finite element model,and the piston fuel injection forced cooling oscillation model,the temperature and stress field finite element model are also established..The original engine cooling water jacket CFD calculation,piston fuel injection forced cooling oscillation calculation,body-cylinder-cylinder head integrated temperature field fluid-solid coupling calculation,piston temperature field calculation,integration and piston stress field analysis,integration and Piston high-cycle fatigue analysis,and control calibration with the temperature of the measured point,it is analyzed that each important part of the original machine meets the restrictive conditions.(2)Under the condition of guaranteed power,study thirteen single factors,including five exhaust pipe structural factors in different supercharging methods,four factors in the air distribution system,and two factors in the fuel system,as well as compression ratio and cooling.The influence of the water temperature at the inlet of the water cavity on the thermal load of each component.The results show that,except for the insignificant factors,the order of the influence of these single factors on the thermal load of the cylinder head and piston under the two exhaust back pressures is:the order of the degree of influence on the cylinder head under low back pressure is:compression ratio>Exhaust duration>fuel injection advance angle;the order of the degree of impact on the cylinder head under high back pressure is:intake duration>intake valve opening time>exhaust duration>compression ratio>fuel injection advance angle>exhaust valve Opening moment;the degree of influence of various factors on the thermal load of the piston under the two back pressures is between the degree of influence on the thermal load of the cylinder head under high and low back pressure.The order of the degree of influence on the piston under low back pressure is:compression ratio>intake Valve opening time>intake duration>fuel injection advance angle>exhaust duration;the order of the effect of high back pressure on the piston is:compression ratio>exhaust duration>fuel injection advance angle>intake valve opening time.The influence of various factors on the thermal load of the cylinder liner under two back pressures is similar to that of the cylinder head.The order of the degree of influence on the cylinder liner under low back pressure is:compression ratio>exhaust duration>fuel injection advance angle,some factors The degree of influence on the cylinder liner is also ob vious under high back pressure.The order of the degree of influence of each factor is:intake valve opening time>exhaust duration>compression ratio>injection advance angle>exhaust valve opening time.(3)Carry out optimization analysis,remove structural factors,and perform one-dimensional calculation and analysis on three factors,namely intake valve opening time,exhaust valve opening time,and fuel injection advance angle,which have a large influence,and take three of them with lower load.Three-dimensional finite element calculations are performed under operating conditions,and it is obtained that when the intake valve opening time is 315℃A,the exhaust valve opening time is 105℃A,and the fuel injection advance angle is 13℃A,the component thermal load is the lowest.