The heat transfer phenomena occurring during the initial phases of in-flight ice formation and accumulation on aircraft surfaces are not completely understood. The aim of this investigation was to quantify the local apparent heat transfer enhancement on surface roughness elements intended to mimic the early stages of ice accretion. In order to achieve this objective, a new technique for mounting gold-deposition Mylar film in a gold-side down orientation was developed and tested. Gold deposited Mylar film is commonly used to establish a constant heat flux convective boundary condition for wind-tunnel test surfaces. However, the accepted mounting technique causes problems if the films are used to explore convective heat transfer from surfaces with high thermal conductivity protuberances and surface roughness. To overcome the problems with roughness-element attachment, a new technique for mounting gold-deposition Mylar film in a gold-side down orientation was developed and tested. After validating the new mounting procedure, a large test plate was created following the same technique and was mounted in a wind tunnel. Using infrared thermometry to acquire temperature profiles of a gold Mylar heated flat plat prepared with three hemi-spherical roughness elements of varying thermal conductivity, the apparent enhancement of the elements was evaluated for varying tunnel velocities. Flow characteristics at and behind the roughness elements were also examined using the infrared images. This study presents the results of the new Mylar film mounting procedure and the apparent enhancement and flow results.
X-Ray Reflectivity Measurements of Surface Roughness Using Energy Dispersive Detection
