Exhaust Manifold Design Based On The Respiratory System And Finite Element Analysis

The engine exhaust manifold is a major component of the exhaust system, The engine power, economy and emissions.was directly impact by the flow properties and thermodynamic properties of exhaust manifold. However, the details of the manifold structural is a highly commercial secrets, domestic study of exhaust manifold is always carried out by simulation of existing manifold,and changed the local structure to achieve the purpose of design optimization. So, exhaust manifold with reasonable structure and superior performance has important theoretical and practical significance.The function of automotive exhaust system is very similar to human respiratory system. Ideas that taking bronchopulmonary as the bionic object to do the exhaust manifold design using the principle of bionics are proposed in this paper. Exhaust manifold with bionic significance is designed combined with medicine and anatomy empirical formula and bionic principles by the analysis of the structure of the human lung bronchial; The paper takes a 2v engine exhaust manifold as the comparison, and ensures that the bionic exhaust manifold and 2v exhaust manifold have the outlet and inlet with the same size and structure in the design.The structural characteristics of the lung tubes is researched, the relevant parameters of the relationship between size and structure are analyzed, a bionic exhaust manifold contour is designed based on this, three-dimensional solid model is establishe, the flow and coupled thermal field of traditional 2v exhaust manifold and biomimetic exhaust manifold are analyed, and their relevant distributions are obtained. The results show that, bionic exhaust manifold exhaust uniflrmity of every branch is better than 2v exhaust manifold; outlet temperature of bionic exhaust manifold is lower than that of 2v exhaust; energy loss of bionic exhaust manifold is reduced, circulation performance is increased, the uniformity of the every pipe flow is improved; bionic exhaust manifold eddy-current interference between every two branches is also smaller than that of 2v exhaust manifold, and the decrease of eddy current directly reduces the resulting noise.The modal analysis of bionic manifold is carried out, vibration mode and natural frequency of the top 10 modes are obtained, and the natural frequency of bionic manifold are away from the engine's operating frequency, ensure that bionic exhaust manifold will not produce resonance under the normal working conditions. Simulation results show that:under the same stiffness and vibration, the quality of bionic exhaust manifold is reduced by 54.3%, the manufacturing costs are reduced largely. It offers a new way to the desigh of exhaust manifold.