Unsteady Heat Transfer and Phase Changing Process Within Small Icing Water Droplets

We report progress made in our recent effort to develop and implement a novel, lifetime-based molecular tagging thermometry (MTT) technique to quantify unsteady heat transfer and phase changing process inside small icing water droplets pertinent to wind turbine icing phenomena. The lifetime-based MTT technique was used to achieve temporally-and-spatially resolved temperature distribution measurements within small, convectively-cooled water droplets to quantify unsteady heat transfer within the small water droplets in the course of convective cooling process. The transient behavior of phase changing process within small icing water droplets was also revealed clearly by using the lifetime-based MTT technique. Such measurements are highly desirable to elucidate underlying physics to improve our understanding about important micro-physical phenomena pertinent to ice formation and accreting process as water droplets impinging onto wind turbine in cold atmospheric environment.