Global Temperature Mapping and Crystallization Analysis of a Supercooled Water Droplet Impact Icing using Luminescent Imaging Technique 2019-01-2009
A prominent environmental phenomenon that greatly affects many industries including automotive, aeronautics, energy transmission, etc. is icing. One mechanism by which this occurs and plagues our machines and infrastructures exposed to the atmosphere is the icing of supercooled water droplets on a surface – either by impact against a surface or spontaneous nucleation and crystallization of a droplet at rest. Understanding how nucleation propagates during the liquid-to-solid phase change and the thermodynamic implications in regards to latent heat generation and transfer on the single droplet scale is critical to modeling and prediction efforts. An attempt to resolve these unknowns in both spatial and temporal domains has been made here. A thermally sensitive luminescent paint coated onto the surface of interest allows direct mapping of the heat transfer from the supercooled droplet undergoing freezing to the surface. To gain a more global understanding of the heat generation and exchange with the environment, supercooled droplets doped with temperature-sensitive luminescent dye is observed while freezing. This, in conjunction with a high-speed color photography, is used to accurately resolve the thermal energy within the freezing droplet in both space and time. Synchronization of the thermal data of the droplet with the measurements of transverse heat transfer through the impact surface allow an estimation of heat generation and loss to the environment – key factors in current modelling and simulation efforts used by researchers and industry to predict ice accretion and to better mitigate it.
Wesley Chad Patterson, Hirotaka Sakaue
Univ. of Notre Dame, Univ of Notre Dame
International Conference on Icing of Aircraft, Engines, and Structures