Engine Performance Simulation Model And Software Development

In the conceptual design stage of diesel engine,developers need to estimate some macro performance parameters.In the existing commercial software of diesel engine,GT-Power and Boost are most widely used.Although the commercial software is powerful,the core algorithm is protected by commercial terms,and developers can not view and modify.More importantly,the commercial software is not suitable for the initial design stage of engine development,because they need to input more diesel engine parameters,the process is complicated and the calculation speed is slow.To solve those problems,it is very necessary to develop a diesel engine performance simulation and emission prediction software with independent intellectual property rights.It can not only guarantee the speed of simulation,but also have friendly interface and powerful data interactive function.It is a practical tool in the initial design phase of engine.The main work is as follows:(1)With the help of UML,a real environment modeling tool,the Classes,Use Case Diagram,Sequence Diagram and Activity Diagram of this diesel engine simulation software are analyzed.Through this method,the whole framework,the relationship between each part and functional requirements of this software are clearly described.Technical team has an accurate understanding and cooperates with each other in the project development process.(2)Based on the understanding of requirements,the author used the object-oriented language C# to quickly create Winform interface and form controls.Besides,the calculation module kernel is written by Fortran and compiled as a executable file for the main program.(3)According to the working principle of diesel engine,the simulation module based on zero dimension model was established.It's able to quickly and accurately predict performance parameters such as power,fuel consumption,torque,etc.This software can plot changing process of some parameters such as cylinder pressure,temperature,heat release rate,intake and exhaust valve flow,etc.(4)The author coupled the NOx semi-empirical model with the zero dimensional model to estimate NOx emissions by fuel consumption rate,adiabatic flame temperature,engine speed,chemical reaction conditions(including activation energy,fuel composition,nitrogen balance concentration and oxygen equilibrium concentration),etc.The model empirical parameters were calibrated.(5)The complex soot generation process was abstracted into two stages: generation and oxidation.Soot emission was simplified as the difference between Hiroyasu generation model and NSC oxidation model.The empirical parameters of the model ware calibrated and the influencing factors of the model ware analyzed.(6)In order to verify the simulation results,a single cylinder direct injection diesel engine was studied and the simulation model was built in GT-Power.The author compared the performance data and emission data under four different conditions.It was found that the calculated results of the software were close to the GT-Power and the experimental values.Thus the accuracy and feasibility of this simulation software for performance calculation and emission prediction were verified.