Numerical and Experimental Study on Freezing Process of Supercooled Water Droplets in Consideration of Non-equilibrium Effects

摘要

Aircraft icing is a typicalsolidification process of supercooled water droplet impacting on the surface of aircraft and presents a significant threat to the performance and flight safety of aircraft.Non-equilibrium solidificationis an important phenomenon in freezing of supercooled waterin aircraft icing process.Based on Enthalpy-porositymodel,amodified numerical prediction method in consideration ofnon-equilibrium effects for solidification of supercooled water was developed.The experimental setup for droplet freezing was build up and solidification experiments were performed to validate the proposednumerical method.The results indicate that the proposedmodel in this work is valid and can be used to predict the solidification characteristics of supercooled water.Based onthe freezing model,the influence of the degree of supercooling and cooling conditions onthe freezing characteristics of supercooled droplet were analyzed.When the degree of supercooling is decreased to zero,the proposedmodel degenerates to the traditional Enthalpy-porositymodel.The greater the degree of supercooling or smaller the droplets scale,the relatively higher the solidification rate.In consideration of the effect of non-equilibrium solidification conditions,the freezingand moving rate ofinterface is higher than the results based on the traditional model.Related research willprovide important reference for improving icing thermodynamic modeland refining theprediction method for icing accretion.