水基纳米流体在竖直毛细管中的气液两相上升流流型特性

研究了在内径为1.6 mm的竖直玻璃毛细管圆管内的氮气-CuO水基纳米流体的上升两相流流型分布图.首先对毛细管内氮气-去离子水的两相流流型进行实验研究,并与常规管的半理论半经验公式进行了比较.然后在水中添加不同比容积的十二烷基苯磺酸钠(SDBS)和CuO纳米颗粒制备成纳米流体,对氮气-纳米流体在垂直毛细管内的流型图进行了测量.研究发现,和常规管相比,毛细管内气-水两相流各种流型的转化在较低的流速下就已产生.使用纳米流体后,毛细管内的气液流型转化在更低的流速下产生.纳米流体对两相流流型的影响主要是由于添加表面扩散剂SDBS和纳米颗粒后降低了溶液表面张力而产生的.纳米流体中的纳米颗粒和表面扩散剂浓度对流型图几乎无影响.

The Flow Pattern Map of Two Phase Flow of Nitrogen and Water Based Nanofluids in a Vertically Capillary Tube

Flow pattern map of the two-phase flow of nitrogen and water based CuO nano-liquid in a vertical capillary tube was investigated experimentally.The working gas is nitrogen and the working liquid is the suspension consisted of water,CuO nano particles and Sodium dodecyl benzol sulphate solution(SDBS).Flow pattern map and pressure characteristic of nitrogen-water in a vertical capillary tube were firstly investigated and the result was compared with the models for the medium and large diameter tubes.Then,different specific volume SDBS and CuO nano particles were added into water to make a series of water based CuO nano-liquids.The flow pattern characteristics of the nano-liquids in a vertical capillary tube were investigated.The results show that for the gas-pure water flow in the capillary tube,the flow pattern transitions for gas-liquid two-phase flow occur at relatively low flow velocities compared with the common tubes.For the gas-nano liquids flow in the capillary tube,the flow pattern transitions for gas-liquid two phase flow occur at lower flow velocities compared with the gas-water in the same capillary tube.The effect of the gas-nano fluids on the two phase flow pattern resulted mainly form the change of the surface tension.Since the surfactant and nano particles decrease the surface tension of the nanoliquid,the flow pattern transitions for gas-nano fluids occur at much lower velocities compared with the case of the gas-water.The concentrations of the nano particles and SDBS have little effect on the flow pattern map of the gas-nano fluids.