Analysis Of Engine Coupled Thermo-Mechanical

Engine as a power device, has been widely used in automotive, marine, aviationand plays an important role in the national economy. But the engine by the heat load andmechanical load in the entire work process, under the action of the load in the couplingwill cause the engine fault and strength problems. These problems will lead to decline inthe power of the Engine, shorten the service life, and even not work.Through a Multi-field coupling simulation analysis of engine, we can get the flowfield of the water jacket, the temperature field of cylinder block, and the stress,deformation of engine. The analysis is useful to find the design flaws of the Engine.However, engine coupling simulation analysis involves multi-disciplinary knowledge ofheat transfer, thermodynamics, fluid mechanics, solid mechanics and mechanics ofmaterials, and each member of the structure is very complex. Therefore, how couplingthe various components and the physical field, and how to solve the import of thetemperature boundary, control transient analysis solution time and solving divergence isthe key and difficult problems in the study. In this paper, based on the finite elementmethod, used the engine which is in the development as a research objectives.Established heat exchanger model of engine, and based on the temperature of the heatexchanger model, Research on the strength of the coupling of the engine. The maincontents and conclusions are as follows:First, in order to obtain the mesh models and boundary conditions, on the basis ofthe simulation is accurate, fast calculation. To clean up the geometric model of cylinderblock, cylinder head, water jacket, and then create each mesh model. Calculated wallheat transfer boundary conditions based on Thermodynamics and Cylinder heatexchange experience formula. And calculated mechanical based on force analysis ofcrank.Second, established the engine conjugate heat transfer finite element model, whichcomposed by Cylinder, cylinder head, water jacket. And analysis the simulation resultsfrom two aspects of the flow field, temperature field at the same time. The study resultsshowed that: The cylinder head on the maximum temperature of198.8℃, which areVery close to the limit temperature of creep and thermal fatigue. Therefore, need toimprove the design of the water jacket.Third, solved the problem of importing boundary conditions, solving time is long, and the solution does not converge by Matlab programming, a reasonable set of thermalconductivity, damping, and constraints. Then, completed thermal stress simulation andtransient analysis of thermal-mechanical coupling with ls-dyna software. The studyresults showed that: In the cylinder head temperature does not meet the designrequirements of the case, the cylinder block, cylinder head, stress, deformation may beable to meet the requirements, therefore, to ensure that the all respects of the engine tomeet the design requirements, temperature, stress, deformation of various aspectsassessment.Finally, in order to decrease temperature of the cylinder head nose area.Improvements had done on water jacket according to law about the flow fielddistribution of water jacket between cylinder head temperature field. After improved,the maximum temperature of the cylinder head decreased from198.8℃to185.6℃.And study of deformation and strength on improved structure. The study results showedthat: the improvements of water hole distribution are very effective to improve thecooling of the water jacket, Temperature, strength, deformation and eventually meet thedesign requirements.According to the study we can see this article effectively solve the multi-fieldcoupling simulation problems of engine, and to discover, solve design defects anddeficiencies in the engine development, shorten the design cycle of the engine to speedup the development process. This is not only the design and development of the enginehas certain significance, but also provides a way for the engine coupling studies.