- 學位論文
靜態混合器內混合現象的數值研究
Numerical study of mixing phenomenon in static mixers
摘要
本論文利用有限元素法計算軟體COMSOL Multipysics，來模擬在層流條件下肯力氏(Kenics)與SMB-R靜態混合器中的混合現象，分別利用其中的流體粒子追蹤法(Fluid Particle Tracing)、稀薄質傳法(Transport of Diluted Species)和水平集法(Level Set Method)輔助進行數值分析。所計算流場及濃度場經與文獻中計算及實驗結果驗證無誤後，就牛頓流體與非牛頓流體，在不同雷諾數或底波拉數下，本文分析了流經上述兩種混合器中不同混合單元後的混合結果，並獲致如下結論：(1)上述三種方法均能用以評估靜態混合器中伴隨複雜幾何結構而來的對流效應所引致的混合效果。就所需的計算資源言，以粒子追蹤法最低、稀薄質傳法次之，水平集法最高；但後者能追蹤待混合二相的界面變化，更能掌握混合的物理現象與了解其機制。(2) SMB-R混合器總體表現較肯力氏混合器佳，但壓降明顯較大，且在低雷諾數下肯力氏混合器有較佳的混合效果。 (3)剪切稀化有助促進混合。
並列摘要
Numerical simulations were performed for the mixing phenomena inside two static mixers, Kenics and KMB-R mixers, using Fluid Particle Tracing, Transport of Diluted Species and Level Set Method, with the aid of COMSOL Multiphysics software. The simulated flow and concentration fields were validated by comparing with the experimental and numerical results in the literature. Detailed numerical simulations were then performed for both Newtonian and non-Newtonian fluids through Kenics and KMB-R mixers, under different Reynolds and Deborah numbers. We found: (1) The above three methods are capable for assessing the mixing performance of mixers due to the convective effect associated with the complicated geometries inside the mixers. As for the computer resources required, Fluid Particle Tracing requires the least, Transport of Diluted Species the middle, and Level Set Method the most. However, as the Level Set Method can trace the time evolution of the interface between two fluids, it provides us more details about the mixing phenomenon and mechanism. (2) The overall performance of the SMB-R mixers is better than that of the Kenics mixers, but the pressure drop is significantly larger and the Kenics mixers has a better mixing effect at a low Reynolds number. (3) Mixing is increased associated with the shear thinning effect in non-Newtonian fluid.