矩形空間中移動物體之動態流場與熱傳特性研究

Abstract

本研究數值分析在潔淨室內移動物體對氣流流場與塵粒擴散的影響及槽道中移動凸塊對熱傳增益的效果，此種物體與流體交互作用所誘導的流場、溫度場及濃度場變化屬於動態的移動邊界問題。研究中以葛拉金有限元素法，採用ALE (Arbitrary Lagrangian-Eulerian)座標系統，首先探討潔淨室內無人搬運車(automatic guided vehicle, 簡稱AGV)移動及晶圓匣放置位置對氣流流場的影響，其次探討潔淨室內工作平台有/無加裝氣簾下，工作人員移動對氣流流場與微粒子擴散的影響，最後探討槽道中凸塊的移動距離對流場和熱傳的影響。 綜合所獲得的研究結果，可以很清楚地觀察到當物體在流動的流體中運動時，物體推擠流體和流體填補因物體移動所產生空洞的現象。此外，由潔淨室排除微粒子的觀點而言，相對較小的工作人員或AGV移動速度及相對較大的氣流進口速度，有利於微粒子的排除。加裝氣簾能有效保護工作人員免於有害氣體之危害，但AGV上面晶圓匣的放置位置則影響不大。槽道流中凸塊來回移動時，凸塊推擠前方流體而破壞其前方加熱表面之邊界層；同時，牽引後方流體填補凸塊移動所產生的空間，因而在其後方加熱表面上生成新的邊界層，並引導流體流向加熱表面。邊界層的生成與低溫流體流向加熱表面，為增加熱傳效應的主要機制，此外，凸塊移動距離的增加，能成比例地增加熱傳效果。

The aim of this paper is to investigate the motions of the airflow and particles induced by a moving body in a cleanroom and the effect of enhancing heat transfer rate by a moving block in a channel flow. These variations of the flow, thermal and concentration fields induced by the interaction between flowing fluid and a moving body become time-dependent and belong to a class of the moving boundary problems. In this study, a Galerkin finite element formulation with an arbitrary Lagrangian-Eulerian (ALE) kinematic description method is adopted. At first, the variations of airflow induced by a moving AGV in a cleanroom are investigated. The effect of the wafer cassettes’ position is also examined. In addition, the effects of a moving operator and curtain on airflow and particles in a cleanroom are studied. Finally, the effect of moving distance of a moving block on heat transfer in a channel flow is studied. Based upon the above procedures, the results show that the body may press the fluid before the body, and the fluid will simultaneously replenish the vacant space induced by the movement of the body. These phenomena are apparently different from those of regarding the moving body as stationary one in the flowing fluid. From a view point of removing the particles, the relatively smaller moving velocity of the operator or AGV and the relatively larger velocity of the inlet airflow are expected. The curtain can usually protect the operator from the hazardous gases. However, the effect of the position of the wafer cassettes can be neglected. The boundary layer on the heated surface is destroyed before the moving block and reforms behind the moving block in a channel. The major heat transfer enhancement mechanisms are the reformation of boundary layer and the induced cold fluid flowing toward the heated surface. Besides, the heat transfer rate of the heated surface increases proportionally to the increment of the block moving distance.