本實驗之目的，是想建立一可應用於低速管流之低成本、非套裝式的粒子影像測速儀。其中系統主要光源為具180mJ輸出之Nd-YAG脈衝雷射。研究中參考過去流場粒子沉積控制及觀測的結果，探討流速與激擾頻率間的相互關係。 實驗中主要可分為兩大部分探討，(1)無激擾管流、(2)激擾管流：無激擾管流主要檢測流體在無激擾的情況下之流況，藉由熱線測速儀所量測的結果顯示，在距離管道出口5cm之紊流強度值均在6.50×10-3左右；激擾管流則是探討聲波激擾下管道中懸浮粒子的運動情形，當相位角度較小時，分離點會出現在激擾源上方，但隨著相位角度的增加(由0°逐漸增加到360°)，分離點所產生的位置會偏向下游。當相位角度為30°~180°時，則可以得知相位角度的改變不但能改變下游之流場也可以使分離點延後發生，讓上游之流體能量傳遞至後方進而減少粒子沉積在管道之中。 The main objective of this study is to set-up a low-cost, non-packaged particle image velocimetry which can be used for low-speed pipe flow where the major light source of this system is an Nd-YAG pulsed laser whose power output is 180mJ. Base on previous experimental results about the control of particle disposition and flow visualization, the interaction between excitation frequency and exist wind speed will be well investigated in this study. The experimental discussions can be divided into two parts, (1) non-excited pipe flow; (2) excited pipe flow. The non-excited experiments mainly examine the flow fundamental properties. Via the hot-wire measurement, the value of turbulent intensity is about 6.50×10-3 at the location of 5cm away from pipe exit. And the experiments of excited pipe flow investigate the motion of drift-particles under acoustic excitation in pipe flow. At lower phase angle, the separation point will appear at the top location of the acoustic source. But increasing of the phase angle, the location of separation point will move downstream. The change of phase angle between 30°~180° can not only change the flow field at downstream, but also delay the appearance of separation point. The energy of the flow field at upstream can convect to far downstream and decrease the particle deposition inside the pipe when phase angle changes.
