Variation of cold-soaked fuel frost roughness with location on a flat plate.

Abstract

Cold-soaked fuel frost occurs when moist air flows over an aircraft surface that is colder than the dew point temperature following a flight. Previous studies show that cold-soaked fuel frost depends on surface temperature, air temperature, surface geometry, exposure time, and Reynolds number. However, variation in frost roughness due to location on a plate is not well established for surfaces which scale to sizes expected for commercial aviation. In this thesis, photogrammetry and infrared imaging are used to characterize cold-soaked fuel frost roughness. The roughness variation is explained by the viscous and thermal boundary layer development. The roughness measurements from this study suggests that frost forms rapidly towards the leading edge of the plate because the viscous boundary layer thickness is small, which amplifies the forced convection over the plate because there is a larger effective velocity over the plate at the leading edge.