Effects of Pore Geometry on Intrafloc Flow

內孔幾何形狀對膠羽內部流之影響

朱敬平(Ching-Ping Chu) ； 李篤中(Duu-Jong Lee)

《Journal of the Chinese Institute of Chemical Engineers》 35卷6期 (2004/11) Pp. 659-666

https://doi.org/10.6967/JCICE.200411.0659

摘要

廢水汚泥膠羽之內部流動主要由其中之大孔道所控制，而經由螢光原位遵命雜交法(FISH)及掃瞄式聚焦雷射顯微攝影(CLSM)技術可發現膠羽內之大孔道爲具非圓形截面及碎形邊界之扭曲孔道，因此欲進行數值模擬前必須簡化孔道幾何形狀之複雜度。本文以數值模擬探討孔道邊界粗糙度、扭曲度及截面形狀對流場及壓降之影響，結果顯示孔道扭曲度因可改變主流場 方向而對壓降有最大之影響，其次邊界上之“主要”粗糙度亦爲一重要之幾何參數，而在大範圍之尺寸比下非圓形截面驛膠羽之內部流動影響不大，正確找出孔道質量中心以決定其扭曲度成爲建立適當汚泥膠羽內部流動模型之關鍵因素。

並列摘要

Large pores in wastewater sludge floe control intrafloc advective flow. Such pores, probed using fluorescence in situ hybridization (FISH) and the confocal laser scanning microscope (CLSM) technique, exhibited zigzagging with a non-circular cross-section and fractal-like boundary. Simplification of the complicated pore structure was needed before modeling could be conducted. This work demonstrated, using numerical simulation, how the roughness of the pore boundary, the pore zigzaggedness, and the shape of the pore cross-section affected the flow field and the associated pressure drop in a simulated pore. Simulation revealed that the pore zigzaggedness changed the direction of main-stream flow in pore mostly affected the pressure drop. The “main” boundary irregularity was also found to be an important geometric parameter. Over a wide range of aspect ratios, the non-circular (elliptic) had cross-section only a mild effect on the advective flow. Correctly allocating the centroids of pores in order to reveal their zigzaggedness is necessary to adequately model advective flow through floe pores.

並列關鍵字

Floe structure ； Advective flow ； Geometry ； Pressure drop ； Simulation