In-flight icing on unmanned aerial vehicle and its aerodynamic penalties

A numerical prediction of ice accretion on HQ309, SD7032, and SD7037 airfoils and its aerodynamic penalties is described. Ice accretion prediction on a three-dimensional (3D) swept wing is also presented. In addition to airflow and drop trajectory solvers, NRC's (National Research Council) original, 3D, morphogenetic icing modeling approach has been used. The analysis was performed for a wide range of icing conditions identi\ua6ed in the FAA (Federal Aviation Administration) Appendix C icing envelope. They cover a range of drop sizes, air temperatures, and liquid water contents. For selected icing conditions, the resulting decrease in lift and increase in drag have been calculated.Peer reviewed: YesNRC publication: Ye

Surface Instability of Icicles

Quantitatively-unexplained stationary waves or ridges often encircle icicles. Such waves form when roughly 0.1 mm-thick layers of water flow down the icicle. These waves typically have a wavelength of 1cm approximately independent of external temperature, icicle thickness, and the volumetric rate of water flow. In this paper we show that these waves can not be obtained by naive Mullins-Sekerka instability, but are caused by a quite new surface instability related to the thermal diffusion and hydrodynamic effect of thin water flow.Comment: 11 pages, 5 figures, Late

In-flight icing of UAVs - The influence of reynolds number on the ice accretion process

The intensive deployment of UAVs for surveillance and reconnaissance missions during the last couple of decades has revealed their vulnerability to icing conditions. At present, a common icing avoidance strategy is simply not to fly when icing is forecast. Consequently, UAV missions in cold seasons and cold regions can be delayed for days when icing conditions persist. While this approach limits substantially the failure of UAV missions as a result of icing, there is obviously a need to develop all-weather capabilities. A key step in accomplishing this objective is to understand better the influence of a smaller geometry and a lower speed on the ice accretion process, relative to the extensively researched area of in-flight icing for traditional aircraft configurations characterized by high Reynolds number. Our analysis of the influence of Reynolds number on the ice accretion process is performed for the NACA0012 airfoil. Analytical analysis of the integrated mass and energy balance equations along the airfoil surface allows the identification of regimes of rime and glaze formation, as well as the ice accretion extent as a function of static air temperature and liquid water content. For each Reynolds number, a CFD solver computes the airflow field, and the distributions of Stanton number and static air pressure along the airfoil surface. Next, a drop trajectory solver computes the distribution of collection efficiency along the airfoil for a given drop size. Finally, a morphogenetic model is used to predict the ice accretion shape and its extent over the entire Reynolds number range under consideration. Our analysis highlights the differences between ice accretions on components of traditional aircraft and UAVs, arising from their differences in cruising speed and airfoil dimensions. Copyright \ua9 2011 SAE International.Peer reviewed: YesNRC publication: Ye

Derivation and new analysis of a hydrodynamic model of speed skate ice friction

This paper presents the mathematical derivation of a new model of speed skate ice friction. The model acronym is FAST, which stands for friction algorithm using speed skate thermohydrodynamics. Mutatis mutandis, it is applicable to other ice friction problems in the hydrodynamic friction regime. This paper updates and corrects an earlier publication of the model that omitted the full derivation of the lubrication equation (Penny et al., 2007). It also updates the ice hardness equation based on new measurements, and it presents a more thorough exploration of the model results and its sensitivity to the variation of physical variables. \ua9 by The International Society of Offshore and Polar Engineers.Peer reviewed: YesNRC publication: Ye

FAST 2.0 derivation and new analysis of a hydrodynamic model of Speed Skate ice Friction

This paper presents the mathematical derivation of a new model of speed skate ice friction. The model acronym is FAST, which stands for Friction Algorithm using Speed Skate Thermohydrodynamics. Mutatis mutandis, it is applicable to other ice friction problems in the hydrodynamic friction regime. The paper updates and corrects an earlier publication of the model (FAST 1.0) that omitted the full derivation of the lubrication equation. It also presents a more thorough exploration of the model results and its sensitivity to the variation of physical variables. Copyright \ua9 2011 by the International Society of Offshore and Polar Engineers (ISOPE).Peer reviewed: YesNRC publication: Ye

Three-Dimensional Modelling of Ice Accretion Microstructure

Peer reviewed: YesNRC publication: Ye

2.5-D Modelling of Rime Ice Accretion on a Swept Airfoil

Peer reviewed: YesNRC publication: Ye

Cloud Feedback Examined using a Two-Component Time-Dependent Climate Model

NRC publication: Ye

Simulation of Airfoil Icing with a Novel Morphogenetic Model

NRC publication: Ye