The Design Of Optimal Design System Of Micro Axial Flow Fans Based On 3-D Flow Field Analysis

Micro axial flow fan is mainly used in computers, electronic instruments and other electronic components for cooling and ventilation. With the development of computer industry, the higher performance axial flow fan is also needed as the heat increases on account of the computer speed enhanced. In this paper, an optimization design system for the miniature axial flow fan on the basis of the theory of axial fan design, the flow field calculation and optimization algorithm was established, provide method of optimization design for miniature axial flow fan, improved the problem such as in some conditions the performance can not reach requirements, which brought by continue the design method of large fan. This work has certain theoretical meaning and engineering application meaning.This optimal design system of micro axial flow fan is comprised of fan design module, pre-treatment module, flow field calculation module and fan optimization module as following:(1) Through the fan design module the three-dimensional model of the fan can be obtained by isolating the leaf and adjusting the shape of fan blades more flexibly. And three-dimensional model will be saved as prt and igs files, which will be called by pre-treatment module.](2) The pre-treatment module imports the igs file, sets the mesh size, diameter and height of rotating fluid area, pipe zone, import extension, export extension and other parameters, then calls Gambit to creat the mesh. The results will be saved as msh file and called by the flow field calculation module.(3) Importing the above msh file , setting the boundary conditions , rotation speed, turbulent kinetic energy, relaxation coefficient, upwind scheme, convergence error and other parameters, the flow field calculation module figures out the flow field by calling the calculation module of Fluent,and saves the results as cas and dat files.(4) Genetic algorithm is adopted to optimize hub ratio, installation angle, airfoil curvature, tip clearance and the length of chord in the process of fan optimization module. In order to get the fitness value, we carry on the non-negative and maximize processing by using Fluent calculation results as the objective function values. What's more, the results are calculated by Fluent, making sure the optimization results are accuracy and reliable.(5) The system is designed in modular using C++ and Open GRIP as the development language. All of the four modules can be programmed and debugged independently,so it's very convenient to upgrade and maintain. Plus, the fan design module, pre-treatment module, flow field calculation module can be used alone or in series with the fan optimization module for optimizing. Each module communicate with other modules through the data file.By calling the four modules, the system carries out the designing, creating mesh, meshing, calculation and optimization of flow field since the axial fan design objective is set, obtaining the best performanced fan and exporting the three-dimensional model and flow field information.