Exhaust Manifold Thermal Assessment with Ambient Heat Transfer Coefficient Optimization

Exhaust manifolds are one of the most important components on the engine assembly, which is mounted on engine cylinder head. Exhaust manifolds connect exhaust ports of cylinders to the turbine for turbocharged diesel engine therefore they play a significant role in the performance of engine system. Exhaust manifolds are subjected to very harsh thermal loads; extreme heating under very high temperatures and cooling under low temperatures. Therefore designing a durable exhaust manifold is a challenging task. Computer aided engineering (CAE) is an effective tool to drive an exhaust manifold design at the early stage of engine development. Thus advanced CAE methodologies are required for the accurate prediction of temperature distribution. However, at the end of the development process, for the design verification purposes, various tests have to be carried out in engine dynamometer cells under severe operating conditions. The test running durations up to 2500 hours are required for the heavy duty (HD) diesel engine exhaust manifold; therefore they are very expensive and time consuming. In order to avoid this additional costs, having first time capable CAE models is crucial. In this study, one of the heavy duty engine exhaust manifold is carried out for metal temperature validation with external Heat Transfer Coefficient (HTC) optimization. With optimized HTC values which are found with optimization algorithms for one engine operating condition are used for another engine operating conditions to test the correction of values.