Design And Development Of Diesel Engine Cylinder Head For Large Power Marin Application

In recent years,the 12 liter marine engine is rather popular,Weichai company decided to develop one upgrade marine engine based on current truck engine.The power target is 530 kW with power density of 45.62kW/L,at the same time,the emission should fulfil the EPA Tier? regulation.The cylinder head of base engine is not capable for this application with high power density and peak firing pressure.The cooling capability,strength and port performance are the key problems of this project.In order to improve the cooling capability of cylinder head,the top-down cooling concept are are used to redesign the water jacket with a lot of local optimization.The AVL.Fire software are used to simulate the liquid flow in water jacket,by comparing the simulation results of new water jacket with the baseline,the velocity field,convention heat transfer coefficient are improved a lot,which means cooling capability and cooling efficient of the new optimized water jacket are much better than the baseline.Furthermore,The highest temperature in cylinder head are found to decrease by 39? in steady heat transfer analysis of cylinder head through finite element method.Several local structures of cylinder head are modified in order to solve the weakness problem of cylinder head strength.The there dimension model of cylinder head are modelled by Pro/E software,The stress and high cycle fatigue of cylinder head are calculated by numerical simulation,The results shows that the new cylinder head are much strength than the baseline and fulfil the strength requirement of design guideline.To fulfil the fuel economy and emission requirement of marine engine,an performance target of intake and exhaust port are set up through combustion analysis.To achieve this port target,several intake port are tested on steady port flow test bed,the final intake port are selected with the highest flow coefficient and proper swirl number.Four exhaust ports are modelled by CAD and the port flow simulation is done by AVL.Fire software,The final exhaust port are selected with the highest flow coefficient.By using the CAD,numerical simulation and testing methods,the best cooling jacket,strength structure and port are selected based on the comparing the new design scenarios with the baseline.Finally,the poor cooling capability,weakness structure and improper port problems are solved,the completely new cylinder head are designed and suit for the target marine application.