Performance Analysis And Optimization Of A Certain Diesel Engine Exhaust Manifold

The development direction of traditional internal combustion engines is often high power and high compression ratio,as the country has more and more stringent requirements for vehicle emissions.The effective working pressure and combustion temperature of the engine in the working process are getting higher,so the working environment of the exhaust system has become more demanding.The exhaust manifold is the core component of the exhaust system,and its structural design has an important impact on the exhaust efficiency and reliable operation of the engine.In this paper,the exhaust manifold of a diesel engine is selected as the research subject,and the flow characteristics of the manifold are analyzed.Finite element analysis obtains the internal flow law,stress distribution and vibration characteristics.First,create a one-dimensional simulation model based on the one-dimensional thermodynamic simulation software Gt-power based on the data of the diesel engine provided by the manufacturer,and compare the calculated results after operation with theoretical experimental values to determine the reliability of the one-dimensional simulation software’s calculation results.After the calculation results obtain the flow boundary conditions of the internal gas,the flow state is simulated and the flow characteristics are analyzed.Secondly,the temperature field obtained by the flow simulation calculation is coupled to the exhaust manifold as a load,and the boundary conditions are applied according to the actual working conditions of the manifold for thermal stress analysis,and the stress cloud diagram and the deformation cloud diagram of the manifold are obtained.The results show that the manifold is in When the branch pipe is connected to the main pipe,stress concentration occurs and the tail of the manifold is deformed.The manifold is optimized according to the results of the manifold flow analysis and thermal-fluid-solid coupling analysis.The adjusted manifold has a greater improvement in flow performance,thermal stress,and deformation than the original model,indicating that the optimized manifold is more reliable than the original model.Improve before optimization.Finally,the modal analysis of the manifold model before and after the modification is carried out,and the natural frequency table and mode shape of the free mode and the constrained mode are compared.The results show that the natural frequency table of the manifold before and after optimization is much larger than the excitation frequency generated by the engine.Resonates with the engine.