CAJ | 학술논문

测定了不同体积分数下Al2O3-水纳米流体在内径0.193mm和0.508 mm 2种玻璃微圆管内的流动阻力特性.结果表明:纳米流体流动从层流向湍流转变的临界雷诺数Rec发生在2 100附近;对0.508 mm微圆管,纳米流体由层流向湍流的转变与去离子水基本一致,对0.193mm微圆管纳米流体流型转变较去离子水略有提前.在雷诺数小于1 500-1 700的层流范围,纳米流体和水的摩擦因子都与经典理论预测值吻合良好,同Hagen-Poiseuille公式偏差小于7.5%,雷诺数大于此范围后前者的摩擦因子比后者和理论值有所偏高;而在过渡区和湍流范围,纳米流体的摩擦因子比水有较大提高,且随体积分数增加摩擦因子增加的趋势更为明显.
측정료불동체적분수하Al2O3-수납미류체재내경0.193mm화0.508 mm 2충파리미원관내적류동조력특성.결과표명:납미류체류동종층류향단류전변적림계뢰낙수Rec발생재2 100부근;대0.508 mm미원관,납미류체유층류향단류적전변여거리자수기본일치,대0.193mm미원관납미류체류형전변교거리자수략유제전.재뢰낙수소우1 500-1 700적층류범위,납미류체화수적마찰인자도여경전이론예측치문합량호,동Hagen-Poiseuille공식편차소우7.5%,뢰낙수대우차범위후전자적마찰인자비후자화이론치유소편고;이재과도구화단류범위,납미류체적마찰인자비수유교대제고,차수체적분수증가마찰인자증가적추세경위명현.
The flow behavior of Al2O3-water nanofluids in micro glass circular tubes with internal diameters of 0.193 mm and 0.508 mm was measured at different volume fraction. The results show that the critical Reynolds numbers Re of nanofluids in micro tubes at which the transition from laminar flow to turbulent flow occurred are both around 2100. For the 0.508 mm tube, the transition from laminar to turbulent is consistent with that of deionized water; for the 0.193 mm tube, the transition of nanofluid flow behavior is little earlier than that of deionized water. In most of the laminar flow range where Re < 1 500-1 700, the friction factors of both nanofluids and deionized water agree well with the typical predicted value, with the deviation from the Hagen-Poiseuille predictions less than 7.5%. For Re higher than the aforesaid range, the friction factors of the nanofluids are somewhat higher than that of deionized water and the Hagen-Poiseuille predictions, In the region of transition and turbulent fow, the friction factors of nanofluids increase greatly compared with that of water. As the particle volume fraction increases, the difference becomes more obvious.