Simulation and Test Research for Integrated Exhaust Manifold and Hot End Durability 2017-01-2432
In order to reduce emissions, size and manufacturing cost, integrated exhaust manifold become popular in gasoline engine, especially in three-cylinder engine. Moreover, due to shorter length, lighter weight, and less component connections, the exhaust manifold and hot end durability will improve apparently. In this work, an advanced cylinder head with integrated exhaust manifold is adopted in a three-cylinder turbo engine. Because of this integration characteristic, the gas retain in cylinder head longer and the temperature reach higher level than normal cylinder head, which will cause thermal fatigue failure more easily. To validate the exhaust manifold and hot end durability, series simulation and test validation work have been done. Firstly, overall steady state and transient temperature simulation was done for global model. For turbocharger, in order to simulate the outlet turbulent flow and 3d rotation, a code was compiled to define this 3d rotation. In this code, the inlet boundary was defined by turbine blade’s rotational velocity, direction and angle. Secondly, based on temperature prediction, thermal modal, high cycle fatigue (HCF) and thermal mechanical fatigue (TMF) analysis were done in sequence. According to HCF analysis, catalyst bracket fatigue factors fulfilled the require limit. According to TMF analysis, cylinder head life which contains the exhaust manifold fulfilled the life cycle target. Temperature and vibration test were done on rig test, good correlation is shown between test and simulation results. Finally, no crack failure was found inside the cylinder head and hot end after durability test, which also proved the TMF and HCF results indirectly.