For example, the original exhaust manifold of automobile engine is cast exhaust manifold, and its structure is shown in Fig.
It can be seen from the pictures that the exhaust manifold inside the engine is a traditional manifold type. The material has a certain strength and is high silicon molybdenum. In practical application, due to its large mass and heavy average wall thickness, this material will inevitably be affected by its own material and quality during exhaust. Moreover, due to the special form of this kind of exhaust manifold, considering that in the actual operation process, the manifold may fail under the impact of heat and cold, the designer has carried out treatment in some special areas of the manifold and thickened the inner pipe wall. This causes the wall thickness inside the manifold to increase, which will affect its performance during operation.
Through the observation of the internal parameters of the manifold, it can be found that the length of each branch pipe of the exhaust manifold from the cylinder head outlet to the main pipe is short, which causes that the pulse function does not play a good role in the operation of the manifold, which is not conducive to the normal use of the manifold. On the other hand, because the adjacent two ends of the branch pipe are connected. During operation, if one of them fails, it is easy to cause adverse effects on other manifolds. Moreover, through observation, it can be found that during the exhaust stroke of cylinder 1 and 4, cylinder 2 and 3 are in the intake state. Then, the overlap angle of intake and exhaust valves exists in the process of exhaust manifold operation, which leads to the decrease of engine charging efficiency. Therefore, in order to ensure the charging and exhaust efficiency of the engine and optimize the overall performance of the gasoline engine, it is necessary to optimize the design of the exhaust manifold.