Numerical Simulation Of The Transient Flow In Diesel Engine Based On Unstructured Dynamic Meshes

The numerical simulation as an effective analysis and design method has been widely used for the structural design and performance analysis of the internal combustion engine,but most of the three-dimensional simulation software of internal combustion engine is from abroad,however,our independent-developed software is relatively hard to see.Therefore,to cast off the limitation of the commercial CFD software,it is very important to develop general CFD software with our own intellectual property rights and source code.The key technologies of the simulation for the transient flow field in the internal combustion engine cylinder mainly include the processing of the mesh movement,spray model,combustion and chemical reaction mechanism and numerical solution method of the flow field in cylinder,etc.And the processing of the mesh movement is the precondition of every physical models application.Based on the general transport equation solver GTEA,which is independent developed by our research group,studying the mesh movement algorithm,this paper puts forward the solutions of the need of internal combustion engine mesh movement,develops corresponding module,builds the internal combustion engine mesh moving model in the GTEA,and lays the foundation for the transient flow field simulation of internal combustion engine.First,this paper studied several relatively mature basic principles and the implementation algorithm of the unstructured dynamic grid,including local reconstruction algorithm,sliding grid algorithm and dynamic grid layer algorithm,and developed an unstructured dynamic grid model based on GTEA.Second,by combining the unstructured dynamic grid model and the GTE A flow field solver,this paper achieved the stimulations of the flow field that contains dynamic boundary,and tested the accuracy of the unstructured dynamic grid model which is developed through typical numerical example and the ability of the GTEA solver calculating the flow field that contains dynamic boundary.Finally based on the research of the unstructured dynamic grid and the characteristics of internal combustion engine,this paper put forward the method of combining the dynamic layer model and the sliding mesh model to achieve the grid movement in the transient working process simulation of the internal combustion engine cylinder.In conclusion,by adding the dynamic grid model of the internal confusion engine,calculates the transient flow field of the internal combustion engine,this paper proves that dynamic grids can meet the needs of the simulation of the transient flow field in the internal combustion engine cylinder.