Annular flow in microchannels is widely used in the fields of chip heat dissipation and fine chemical synthesis due to its efficient thermal mass transfer.The on-line measurement of the thin liquid film thickness and flow pattern of annular flow was realized by using the Micro-LIF method with an accuracy of±2 μm.The results show that as the gas phase shear force increases,the liquid film thickness decreases,and the wave shape changes from low-frequency and high-amplitude waves to high-frequency and low-amplitude waves.When dichloromethane liquid flow rate is 3 ml/min and the gas content is 0.7,the fluctuation frequency can reach up to 260 Hz.Under the same gas content,the liquid film morphology is determined by the viscosity and surface tension of liquids,the liquid film thickness increases with the fluid viscosity,and the frequency of liquid film fluctuation decreases with the liquid film surface tension.The prediction model of thin liquid film thickness for different fluids was constructed through the force analysis of thin liquid film,and the maximum deviation of the predicted value from the experimental value was±15％.This study clarifies the effects of different fluids and gas velocities on the fluctuations and scales of the liquid film in the microchannel,and provides theoretical guidance for the enhanced heat and mass transfer of the thin liquid film.
关键词
微流体学/两相流/薄液膜波动/激光诱导荧光法/含气率
Key words
microfluidics/two-phase flow/thin liquid film fluctuations/Micro-LIF method/gas content
维普
万方数据