基于重叠网格的皮蛋喷淋涂膜仿真研究

Simulation of preserved egg spray coating based on overset mesh

为了加深对皮蛋喷淋涂膜工艺的认识,使用Fluent软件中重叠网格耦合VOF模型开展两相流研究,获得皮蛋不同摆放姿势下的液膜润湿比,并以膜厚变化指数为响应值,结合Box-Behnken试验筛选出悬垂液滴去除时最优吸管参数与工作压力,结果显示:尖端朝下摆放的皮蛋经过喷淋后液膜润湿比为1,而钝端朝下摆放的皮蛋经过喷淋后液膜润湿比仅为0.836,筛选出最优吸管参数组合为间距14.50 mm、直径12.09 mm、工作压力6.97 kPa、膜厚变化指数预测值为0.636。在最优吸管参数组合下进行仿真试验,并利用气吸装置开展悬垂液滴去除试验,试验结果显示,膜厚变化指数仿真值与预测值的相对误差为1.73%,膜厚变化指数的实际值与预测值的相对误差为7.55%,与仿真值的相对误差为9.12%。结果表明本研究的耦合模型可用于皮蛋喷淋涂膜仿真试验。

The overset mesh model coupled with the VOF model in Fluent software was used to study the two-phase flow to deeply understand the spray coating process of preserved eggs and solve the problems of insufficient theoretical researches on the spray coating of preserved eggs.The liquid film wetting ratio during the coating process under different placement positions of preserved eggs was obtained.The changes of the aspect ratio of the droplets under different pipette parameters were analyzed.The optimal pipette parameters and working pressure for the removal of pendant droplets were selected by the Box-Behnken experiment using the variation index of film thickness as the response value.The results showed that the liquid film wetting ratio of the preserved eggs placed downward after spraying was 1 while the liquid film wetting ratio of the preserved eggs placed with the blunt end down after spraying was only 0.836.The optimal combination of straw parameters screened out was spacing of 14.50 mm,diameter of 12.09 mm,working pressure of 6.97 kPa,and predicted variation index of film thickness of 0.636.The experiments of simulation and the removal of pendant droplets using the air suction device were carried out under the optimal combination of straw parameters.The results showed that the relative error between the simulated value and the predicted value of the variation index of film thickness was 1.73%.The relative error between the observed value and the expected value of the variation index of film thickness was 7.55%,and the relative error between the observed value and the simulated value was 9.12%.Indicating that the coupling model in this study can be used for the simulation test of egg spray coating.