Simulation On Optimization Of Intake And Exhaust System For Turbocharged Diesel Engine

In recent years, a lot of research work on the intake, exhaust and turbocharging system was done around home and abroad, in order to improve the volumetric efficiency and reduce emissions of diesel engine. The objective of this thesis is to study intake and exhaust system of turbocharged diesel engine and matching between each component by theoretical and simulation methodology.In this thesis, firstly, the thermodynamics simulation model for turbocharged diesel engine is established by GT-Power software. The result shows that the computation values agree well with tested values, which proves that the simulation model is reliable. On the basis of this model, the 1-D simulation on flow characteristics of intake system is conducted, from which related boundary conditions are obtained. Furthermore, the characteristics of three-dimensional flow field in intake pipes are analyzed with AVL FIRE software, and the intake unevenness rate between different cylinders is calculated.For further improving the diesel performance, the structural parameters of exhaust system are optimized. After studying the influence of the main structural parameters on performance, an optimization model is set up to obtain maximum power. The computation result indicates that the effect on optimization is satisfying. Also, the simulation method for working process of the engine is applied to study the effect of valve timing on the performance. The optimal values at different engine speeds are attained, based on which, the simulation of diesel engine with VVT is conducted, and its result shows the performance of diesel engine with VVT is enhanced.Finally, the matching of cooler, turbocharger, air filter and diesel is investigated. By means of simulation, the influence of cooling on performance of the turbocharged diesel engine is analyzed. The good matching between turbocharger and diesel is achieved in both load and external characteristics. Besides, the influence of intake resistance of air filter on the diesel engine performance is studied.