風扇流場之數值模擬與實驗量測

Abstract

本文利用數值方法對一般電腦內常用冷卻風扇進行流場之模擬研究，並搭配適當實驗以茲驗證。數值方法上使用有限體積法及紊流k-ε模式模擬風扇在直圓管內之流場。在實驗量測部分，利用放煙線法、熱線測速與壓力量測技術，觀測流道出口流場結構與速度分佈，以及管壁上各點之靜壓值。結果顯示，數值模擬風扇之準確度在70%以上。本文由數值方法中可以得到風扇造成流場之增壓過程，及風扇表面之壓力分佈。根據此結果提出改變中心軸設計，能提升 風扇的壓差、流速及流量。

This study is to simulate a flow field of common used computer fan. A finite volume method is employed to solve the flow field in the fan. During the computing process, the standard turbulent model is used to solve the governing equation of the flow field. In experimental investigation, film the smoke structure by smoke-wire method, measure the velocity by hot-wire technic at outlet of the tube, and record the pressure at wall of the tube. It is shown that the numerical accuracy is above 70%. According to the numerical investigation, the detail structure of flow field and the raising process of pressure can be understood. After analysing the flow field, change the design of centre shaft can increase the pressure, flow velocity and flux.