Turbocharged And Intercooled Diesel Engine Heat Load Analysis

With energy conservation and emission regulations being more strictly, the cylinder pressure of diesel increased to more than16Mpa. Diesel engine will be deformation, leakage, cracking, glue, oil aging, dragging, increased oil consumption and abnormal combustion phenomenon because of high temperature and high pressure, and thermal stress generated by non-uniform cooling. It would be affecting the engine power, economy and reliability seriously. The engine used in this study was a turbocharged inter-cooled diesel, and the main purpose of the experiment was to study the problems of thermal load and non-uniform cooling. Some strategies and solutions in controlling the problems of thermal load and non-uniform cooling were proposed. The following specific research works were carried out.(1) Based on analysis of heat transfer simulate the coupled heat transfer between main engine heated parts,cylinder head-liner-coolant-cylinder block fluid-solid coupled system was created.This coupled system concludes coupled heat transfer between solid and solid,besides coupled heat transfer and flow simulation between fluid and solid.Outer boundary conditions between single parts are converted to inner boundary conditions processed through finite software,so that heat transfer simulation becomes moare reasonable and simpler.(2) One-dimensional model of the cooling system and the three-dimensional model of the cooling water jacket were established based on the coupled sysytem model.This paper proposed some schemes to optimize the structure within water jacket according to the test and simulation results.The follow-up numerical simulation and experimental validation indentified that the heat load of complete machine could be significantly,by adopting these optimized schemes. The optimized scheme was greatly improved compared with the original scheme, in which the cylinder head water jacket and cylinder block jacket average flow rate raised8.1%,9.8%respectively.Cylinder liner flow rate raised21.2%.Besides, the cooling uniformity was improved by51.6%, the pressure losses was also improved.(3) At last,according to the result of the CFD analysis results,the fluid-solid coupling simulation inside the "cylinder head-liner-cylider block"have been completed.The temperature field inside the cylinder head,liner and cylinder block have been gotten by the coupled simulation between the flow field of coolant and the heat transfer of cylinder head,liner and cylinder block. The optimization scheme is better than the original scheme in the temperature and deformation. The largest amount of the temperature for liners’and cylinder water jacket’s improvement reached3.6°C,10°C respectively.The largest amount of the deformation for liners’ improvement reaches14.55%. The average is4.99%, and the amount of the deformation and temperature of the head and body has different degrees of improvement.By means of the fluid-solid coupling simulation,the distribution of temperature inside the cylinder head,liner and block can be acquired in detailed during the initial period for the development of new diesel engine.As result,the structure optimization of cylinder head,liner,block and water jacket can also be done during this period,and then the design period is shorted significantly.