The Simulation Analysis Of Diesel Cylinder-piston Transient Heat Transfer

In modern society, the diesel engine have been widely used in terms oflarge passenger cars, heavy vehicles, ships, construction machinery, generatorsand other groups, it is because the diesel engine has some advantages, such asgood thermal efficiency and economic performance, torque. But bulky and noisymake many people have a bad impression of the diesel engine. With theincreasing demands on economy, power, emissions and other performanceindicators, the standards for design optimization and improvement of dieselengine construction become more and more strict. Therefore, to improve thereliability of the diesel engine is particularly important, and diesel engine canwork more safely and efficiently by optimizing for the internal workingenvironment and conditions of combustion chamber. The foundation of heatbalance analysis and thermal reliability analysis of diesel engine is to study theheat transfer process of main diesel engine heating parts.Based on the analysis for the heat transfer state of combustion chamber, theheat transfer was simulated for the cylinder-piston with the coupling subsystembetween cylinder and piston as the heat transfer model. In coupling system, theaccordingly deposing for contact boundary conditions between the various parts was made, thereby transforming the outer boundary of the original singlepart into inner boundary conditions and calculating directly by the finiteelement analysis software. Then, the transient heat transfer dynamic contactmodel of the system was established and numerically simulation was carriedout for the periodic calibration of diesel transient heat transfer of a workcycle under declared working condition, and the results was compared withthe steady-state heat transfer analysis.The main contents of this paper include:(1) In the diesel engine cylinder liner basic heat transfer law on the analysisof the piston, the piston study established models Liner heat transfer model.Diesel with4100QBZ as an example, in the rated conditions of its steady heattransfer simulation calculation, for later in the piston-liner transient analysis ofthe foundation.(2) the difficulty of applying the difficulties diesel periodic boundaryconditions for the heat transfer process in the inner wall of the cylinder liner,cylinder liner for a single periodic transient heat transfer simulation carried outto solve the problem and determine the boundary conditions imposed by theboundary conditions which piston periodic transfer liner provides a moreoptimized simulation method is more time-saving.(3) In a diesel engine piston the basis of the relative movement of thecylinder liner and periodic analysis of the heat transfer characteristics, theestablishment of a piston-liner based dynamic contact heat transfer model. Computer simulation of the models in the calibration conditions examples piston-cylinder liner surface temperature distribution the piston during calibrationconditions under periodic transient heat transfer conditions liner periodictransient heat transfer, has been and accordingly the pistons heat transferrelationship with the diesel engine cylinder liner reciprocating cycle between thework are analyzed.In summary, the steady-state temperature field of examples piston models,periodic transient temperature field of single cylinder or cylinder-piston can begot by the finite element analysis for diesel engine piston-liner. Analyzed andcompared against the results of numerical simulation for design optimizationand structural improvements to provide theoretical support.