磁性奈米流體懸滴界面性質之研究

Research on Pendant Drop Interfacial Properties of Magnetic Nanofluids

張君輿(Jun-Yu Zhang)

指導教授 ： 翁輝竹

中原大學/工學院/機械工程研究所/碩士(2012年)

https://doi.org/10.6840/cycu201200974

摘要

本論文完成粒子尺寸、粒子體積分率、粒子磁作用力及外加磁場梯度對磁性奈米流體懸滴輪廓與表面張力等界面性質之影響。主要目的在完成磁場作用下，磁性奈米流體懸滴界面性質之分析。首先，我們完成了水基磁性奈米流體之配製。接著，考慮受磁力作用之磁性奈米流體懸滴，藉由能量平衡定理完成Young-Laplace方程式之修正，利用正割法完成非線性方程式求解以預測懸滴輪廓。最後，透過數值預測與實驗觀察之比較，我們完成磁性奈米流體懸滴輪廓與表面張力等界面性質之分析。
針對磁性奈米流體懸滴輪廓分析部分，理論結果發現，在一磁場作用下，當粒子體積分率增加時，使得懸滴頸部內縮增加；粒子磁作用力強度越強，亦使得懸滴頸部內縮增加；當受一外加磁場梯度時，此內縮效應可進一步被放大；針對磁性奈米流體表面張力分析部分，實驗結果發現，當粒子尺寸較小時，表面張力隨粒子體積分率變化關係較為平緩；粒子磁作用力強度越強，亦使得表面張力隨粒子體積分率變化關係較為平緩；隨著磁場梯度強度增加，此平緩效應可進一步被放大。

關鍵字

懸滴輪廓 ； 表面張力 ； 磁性奈米流體 ； 界面性質

並列摘要

This paper presents a study on the effects of particle size, particle volume fraction, particle magnetic interaction, and magnetic field gradient on pendant drop interfacial properties of magnetic nanofluids, including pendant drop profile and surface tension. The main purpose is to conduct an analysis of magnetic nanofluid interfacial properties under an applied magnetic field. First, we complete the preparation of water-based magnetic nanofluids. Then, considering the magnetic fluid drop in an applied magnetic field, we revise the Young-Laplace equation according to the energy balance principle and use the secant method to solve the nonlinear differential equation, so as to predict the pendant drop profile. Finally, comparing numerical predictions and experimental observations, we complete the analyses of pendant drop profile and surface tension of magnetic nanofluids.
For magnetic fluid pendant drop profile analysis, the theoretical results reveal that under an applied magnetic field, increasing the particle volume fraction leads to the enhanced contraction of pendant drop neck; increasing the magnetic interaction strength of nanoparticles also leads to the enhanced contraction. Such a contraction effect can be further magnified by applying a magnetic field gradient. As for magnetic nanofluid surface tension analysis, the experiment results reveal that a nanofluid with smaller particle size results in a more gradual variation of the surface tension with the particle volume fraction; increasing the magnetic interaction strength of nanoparticles also exhibits a more gradual variation. Such a gradualness effect can be further magnified by increasing the magnetic field gradient strength.

並列關鍵字

pendant drop profile ； interfacial properties ； surface tension ； magnetic nanofulids

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