Numerical Simulation And Test Study On Block Head Compound Of Diesel Engine

The Block head compound is the base structure of diesel engine,it has complex structure and lots of load resistances.At the same time,it is almost the only component which is manufactured by diesel engine company itself and required huge investment.It is meaningful and valuable to research the design,simulation and testing technology of block head compound.The starter of this paper is to review the research progress of structure design,numerical simulation and testing technology in block head compound,then together with the development of an complete new diesel engine,the functionality,load requirement and type of block head compound are introduced.Furthermore,the main design factors are discussed in detail,including stiffness,strength,sealing,cooling,acoustics,downsize and manufacturing.To determine the liner support concept,crankcase type and camshaft position,the strength-weakness analysis and highest mark selection method are used.At the other side,the cylinder head type,cooling concept,intake pipe concept and production material are determined based on technology trend analysis and benchmark analysis.The numerical simulation method is discussed in this paper.The detail specification of head bolt and main bearing bolt are determined by the calculation of cover factor and residual force factor,furthermore,an initial tightening procedure is also calculated.To get the final ports of this engine,several loops of port flow measurements are done on test bench.The gas flow distribution in intake port and combustion chamber are got by single cylinder gas flow simulation using finite volume method,the flow velocity results show rather good performance.The temperature and heat transfer coefficient of boundary layer are also exported,and then used as the boundary condition of temperature simulation.The liquid flow in water jacket is simulated using AVL.Fire software,Based on the distribution of velocity and heat transfer coefficient,the shape of water jacket at injector shell area and upper part are modified to get the final water jacket.Several cylinders are selected to form the calculation model of block head compound,the steady heat transfer analysis,stress calculation and high cycle fatigue calculation are done to get the temperature,deformation,sealing pressure and safety factor of cylinder head and crankcase.The sample tensile strength test,port flow test,bolt tightening test,gasket pressure test and liner deformation test are done using manufactured crankcase and cylinder head,the testing results fulfill the design requirements.The piston bore interface development and temperature test are done on test bench,the design of cylinder bore is proved to be functional because neither abnormal wear nor scuffing of piston-liner interface is observed,the highest temperature of cylinder head and liner at first ring position are within the limit.The load cycle test and over load test are done to verify the durability of block head compound,no crack,abnormal deformation,abnormal wear and leakage is found during the durability test,the block head compound is proved to fulfill the durability requirement.