Sealing Performance Analysis for the Flange Joint at the Front End of a High-Power Diesel Engine Exhaust Manifold

The front end of the exhaust manifold in a high-power diesel engine is connected to the cylinder head with a bolted flange joint. The high-temperature gas discharged from the cylinder poses a great challenge to the sealing performance of the flange joint. In this paper, in order to provide a predictive foundation for the sealing design of the flange joint at the front end of a high-power diesel engine exhaust manifold, the finite element (FE) analysis was implemented to determine the contact stress distributions on the joint surfaces under the high-temperature working condition. An experiment was designed and conducted to obtain the contact stresses on the gasket in the testing flange joint under the critical bolt preload needed to meet the leakage rate requirement, which were used to compare with the contact stresses on the gasket in the actual flange joint to evaluate the sealing performance of the actual flange joint. The results show that the sealing performance of the actual flange joint is qualified. Considering the effect of material creep deformation on the sealing performance of the flange joint, the creep analysis was conducted based on the creep constitutive models of the materials obtained through creep tests, and the continuous sealing time of the flange joint at the high working temperature was predicted. This approach of combining numerical simulation with experimental testing can also be used for sealing prediction and design of other bolted flange joints working at high temperatures.