电荷作用对均质-非均质凝结流动的影响

基于Fletcher成核理论及均质-非均质凝结双流体模型,讨论了电荷作用对凝结流动的影响,结果表明:有无电荷影响时,成核率计算公式精度均较高,流场参数的计算结果与实验结果吻合良好,相对误差不超过5%,表明所建的均质-非均质凝结双流体模型具有较高精度.不带电时,加入颗粒半径为5nm颗粒前后流场过冷度差别较小,加入颗粒半径分别为8nm和10nm颗粒后过冷度峰值虽分别降低2K和7K,但均导致自发凝结向下游迁移.当颗粒带电荷量为Q=1e,加入颗粒半径为5nm颗粒情况下对减小成核自由能障、增加非均质成核率的作用最为明显,这一作用在颗粒半径为8nm时较弱,颗粒半径为10nm情况下最弱.当带电量增加至Q=3e时,加入颗粒半径分别为5nm和8nm颗粒情况下峰值过冷度与均质凝结相比分别下降10K和6K,且较明显地抑制了自发凝结发生. 

Charge-effect on the homo-heterogeneous condensing flow

Based on the Fletcher''s nucleation theory and the two-fluid model for homo-heterogeneous condensation, the effect of charge-effect on the condensing flow was discussed. The results show that the formula of the nucleation rate calculation with or without charge-effect both have high resolution. The calculated results are in good agreement with the experimented results and the relative error is not than 5%, indicating that the two-fluid model for homo-heterogeneous condensation has high precision. When the particle is not charged, the difference of supercooling in the flow field before and after the input of particles with 5nm radius is small. Although the input of 8nm and 10nm radius particles reduces the peak value of the supercooling as 2K and 7K respectively, it also causes the downstream migration of spontaneous condensation. When the particles are charged with a unit of electrical charge, i.e. Q=1e, the input of 5nm radius particles shows most obvious effect on decreasing the nucleation energy barrier and improving the heterogeneous nucleation rate. This effect becomes weaker and even weakest with the input of 8nm and 10nm radius particles respectively. As the charge rise up to three units of electrical charge, the input of 5nm and 8nm radius particles reduce the peak value of supercooling as 10K and 6K compared with homogeneous condensation respectively, which also obviously inhibit the occurrence of homogeneous condensation.