振动微液滴的传质机理与模型

提出了微液滴振动传质的机理模型，基于微液滴振动引起的周围流体介质周期性变化流场和基本输运方程，得到简化的传质控制方程及其数值解，模拟结果表明传质组分的浓度分布具有明显的非均匀特征，其迎流面的浓度梯度显著大于背流面，导出的平均Sherwood数和传质速率随振动频率增加而增大.采用电动力学天平中作一维拟简谐振动的十二烷醇微液滴在氮气介质中的蒸发传质实验数据对模型进行验证，结果表明本文模型所预测的平均Sherwood数变化趋势与实验结果一致，平均Sherwood数预测误差为39.5%，说明本文的传质模型能描述此类微尺度下具有周期性运动特征的单个液滴表面传质现象.

MASS TRANSFER FROM OSCILLATING MICRODROPLET AND ITS MODELING

A novel model was presented to describe the mass transfer from an oscillating microdroplet.Based on the periodical flow field induced by an oscillating microdroplet and the basic mass transfer conservation equation, a simplified mass transfer control equation was derived and the corresponding concentration distribution was obtained by means of numerical technique.The simulated results showed the uneven characteristics in the concentration distribution.The gradients of concentration on upwind side of the microdroplet were much greater than those on downwind side.The simulated average Sherwood numbers and the rates of mass transfer were increasing with increasing oscillatory frequency.The trends of simulated Sherwood numbers were consistent with the experimental results of evaporation of an oscillating dodecanol microdroplet in the nitrogen media at a low evaporation rate, where the microdroplet was electrodynamically levitated and forced to oscillate in a nearly sine pattern along the central axis of an electrodynamic balance.The average error of predicted Sherwood numbers was 39.5%. It indicates that the present model is capable of describing the phenomena of mass transfer from the surface of a single oscillating microdroplet.