Icing Process of Small Water Droplets Impinging onto a Frozen Cold Plate

Abstract

I CE accretion on cold surfaces is a topic of great concern for a number of engineering applications. Ice formation and accretion on power cable and radio masts have been found to cause significant damage or completely destroyed the electric equipment on numerous occasions [1]. Aircraft icing is widely recognized as one of the most serious weather hazards to aircraft operations [2]. The importance of proper ice control for aircraft operation in cold climates was highlighted by many aircraft crashes in recent years, like the Continental Connection Flight 3407, which crashed in Buffalo, New York due to ice buildup on its wing, killing all 49 people aboard and one person on the ground, as the plane hit a residential home on 14 February 2009.Wind-turbine icing represents themost significant threat to the integrity of wind turbines in cold weather. It has been found that ice accretion on turbine blades would decrease power production of the wind turbines significantly [3]. Ice accretion and irregular shedding during wind-turbine operation would lead to load imbalances, as well as excessive turbine vibration, often causing the wind turbine to shut off [4]. Icing was also found to affect the reliability of anemometers, thereby leading to inaccuratewind-speed measurements and resulting in resource estimation errors [5]. Advancing the technology for safe and efficient operation of numerous functional devices in atmospheric icing conditions requires a better understanding of the icing physics. While a number of theoretic and numerical studies have been conducted in recent years to develop ice prediction tools for improved ice protection system designs [6–9], many details of important microphysical processes that are responsible for the ice formation and accretion on frozen cold surfaces are still unclear. Fundamental icing physics studies capable of providing accurate measurements to quantify important microphysical processes associated with icing phenomena are highly desirable in order to elucidate the underlying physics. In this study, we report an experimental icing physics study to quantify the transient behavior of the phase-changing and heattransfer processes within small water droplets impinging onto a frozen cold plate. It should be noted that this is a fundamental icing physics study. Instead of reproducing every detail of the icing phenomena for a specific engineering application, the present study was aimed to elucidate underlying fundamental physics to improve our understanding about the important microphysical processes pertinent to various icing phenomena found in nature, which include power cable icing, wind-turbine icing and aircraft icing. To the best knowledge of the authors, this is the first effort of its nature. The new findings derived from the icing physics studies, as the one reported here, will lead to a better understanding of the important microphysical processes, which could be used to improve current icing accretion models for more accurate prediction of ice formation and accretion on frozen cold surfaces, as well as the development of effective icing mitigation and protection systems for various engineering applications.