Papers by Author: Yan Song Wang

Abstract: To study the Volute of Variable Geometry Turbocharger (VGT) flow field and the possibility of providing the basis theory for control strategy and matching with engine, in this paper, a method is presented. The 3D viscous compressible flow in the model of volute and the vanes is simulated by CFD using FVM (Finite Volume Method). And taking some VGT as an example, the simulation is carried out. The result shows that the method can display the distribution of pressure and velocity in the model clearly. The zone and the reasons resulting in loss will be found after analyzing the results, and then the turbocharger can be optimized and redesigned purposeful to reduce the losses resulted from improper figure. The distribution of pressure and velocity at open and close vanes will be found after analyzing the results, and the basis theory for VGT control strategy and matching with engine can be provided.

Abstract: Dimensional tolerance is an important factor for the geometry quality of products. The stiffness matrices of sheet metal components are usually not variational during the process of tolerance analysis; however, material properties of the compliant parts may change in volume production. The variation of the part thickness changes the part stiffness matrix so that the sensitivity matrix is different from that of the assembly with nominal thickness. The paper proposes an improved sensitivity matrix between the incoming part variation and the assembly variation for the assembly with thickness variation. Moreover, the orthogonal design is used to judge the importance of part and thickness variation for the assembly deviation. The proposed method is illustrated through a case study and the results show that the thickness variation influences the relationship between the part variation and the assembly variation. In addition, part variation plays a more important role to assembly variation than the thickness deviation does according to the orthogonal design.

Abstract: Exhaust gas recirculation (EGR) cooler plays an important role in reducing the nitrogen oxides (NOx) emission of diesel engines. By using the CFDesign software, in this paper, the finite element models are established for analyzing the thermodynamic performance of an EGR cooler. The temperature, velocity and pressure fields of the fluids in the EGR cooler are simulated and verified. Based on these models, furthermore, the thermodynamic performance of the EGR cooler with different structures of cooling tube are analyzed, compared and discussed. The results show that, under the fixed pressure boundary conditions, the EGR cooling efficiency can be significantly increased by properly design the fin number of the cooling tube in EGR coolers.

Abstract: A particle swarm algorithm is proposed to generate optimal assembly sequences for compliant assemblies. Firstly, the liaison graph and the adjacency matrix describe the geometry of the compliant assemblies. An assembly sequence is represented by a character string, whose length is the number of all parts. The conceptual tolerance analysis is used to evaluate feasible sequences. Thereafter, the particle swarm algorithm is presented to generate assembly sequences, in which the elite ratio is applied to improve optimization results. Finally a fender assembly is used to illustrate the algorithm of assembly sequence generation and optimization.