Performance Simulation And Exhaust Pipe Optimization Of A Diesel Engine

Diesel engine is the most widely used power plant in the world today,but due to the current global environmental pollution problems,researchers have to improve them so that they can meet the user's requirements for power output and the emission regulations made by the government.This paper comes from the actual project.Based on the basic parameters and models provided by the manufacturer,the 1D simulation model of the diesel engine is established by using GT-Power software.Then adjust and calibrate the diesel engine simulation model according to the data provided by the company,so that the error between the simulation results and the test data is within an acceptable range.Based on the calibrated model,some original parameters of the diesel engine such as the intake manifold diameter,intake duct length and diameter,intake and exhaust valve timing,fuel injection timing,and compression ratio,are adjusted and analyzed.The influence of the relevant parameters on the performance of the diesel engine is compared with the original data,and the optimal parameter values are selected in combination with the actual working conditions.Since this diesel engine is used for locomotives,most of the optimization work is performed under rated conditions.In order to optimize the exhaust system,the Fluent software is used to calculate the flow field of the exhaust pipe in this paper.The boundary condition is obtained from the above simulation.Then,distribution of the flow field is analyzed by pathlines,temperature,pressure and velocity vector.After that,the CREO software is used to establish a three-dimensional model of the exhaust pipe with an injection angle of 60 degrees and 40 degrees.Finally,using Fluent software to analyze the flow field of the newly established exhaust pipe,and comparing the calculation results with the flow field distribution of the original exhaust pipe.The comparison results show that a smaller injection angle is beneficial to reduce the disturbance and backflow of the exhaust gas in the exhaust pipe system.What's more,with a smaller injection angle the pressure distribution in the exhaust manifold is favorable to the conversion of the kinetic energy of exhaust gas into pressure energy.Which in turn helps to reduce the dissipation of exhaust gas mechanical energy.It is concluded that the exhaust pipe system with an injection angle of 40 degrees is preferred.