Analysis And Optimization Of The Heat Load For The Gasoline Engine Stainless Steel Exhaust Manifold

The engine exhaust manifold is one of the key components of the engine exhaust system, it directly related to engine of reliability and durability, while it directly impacted on the emissions performance of the engine, therefore, it is necessary to optimizing design on its structure. Currently, owing to the irrational structure and materials cause non-uniform temperature distribution on the exhaust manifold, arouse the exhaust manifold thermal stress and deformation. At the same time, the vibration of running engine and the heat load cycle of complex factors are the core reasons of the exhaust manifold cracking. The article is based on these issues, to depth analysis the exhaust manifold of the flow field analysis, thermal stress Thermal modal thermoplastic, combined with the simulation model to optimize the structure of the exhaust manifold so as to achieve satisfactory performance.Firstly, building mathematical models with the flow field analysis combined with the theoretical knowledge of fluid dynamics, making use of STAR-CCM+simulation software to analysis the pressure distribution and streamline distribution map on the manifold exhaust manifold. To solve the manifold flow resistance, as well as the effect of the vortex tube, to provide optimization program to realize each cylinder flow uniformity, reduce flow resistance and tube whirlpool, as well as reduce the energy loss.Secondly, adopting the fluid-structure interaction to calculate the temperature field between the exhaust manifold of the internal fluid and solid conjugate heat transfer, at the same time imposed thermal boundary conditions to solve the temperature field, stress distribution and the direction of the X, Y, and Z of the thermal deformation, to seek the location of maximum stress concentration and thermal deformation in three directions for optimizing.Then combined STAR-CCM+and ABAQUS simulation software to realize data transfer and seamless integration, to solve the joint simulation of thermoplastic, thermal modes. the modal model of the exhaust manifold heat in the free state and the state to be bound under the hot modal order thermal modes of natural frequency in-depth analysis to calculate the constraint among a variety of mounting constraints on the vibration of the exhaust manifold, and reasonable imposed manifold constraints on exhaust port mount flange. At the sam time. the selection of the material to comparative analysis of strain rate variation with temperature, given the trend of changes in the steel grain boundaries in the different temperatures, to verify the material reasonably.Finally, to optimizing the structure of the exhaust manifold, combined with the pressure field, velocity field, temperature field and thermal stress field, thermal, modal, thermoplastic and other factors to design weighted optimal structure, and compared with the original model in order to verify the optimization model is indeed greatly improved in the consolidated performance, and to achieve the requirements of industrial production.