Search Results

Cold soaked fuel frost (CSFF) is frost that forms on aircraft wing surfaces following a flight because of cold excess fuel remaining in integrated fuel tanks. Previous investigations by Zhang et al. (2021a) and Zhang et al. (2021b) have focused on experimental measurements and correlation development for frost observed using a small frost wind tunnel employing a thermo-electric cooler to impose a surface temperature for a range of environmental conditions. To model the CSFF approach in more detail, an experimental facility was developed and described by McClain et al. (2020) using a thermal model of an integrated wing fuel tank placed inside of a climatic chamber. In this paper, experimental measurements of CSFF are presented using two aluminum wing skins. One of the skins was created using an aluminum rib structure, and the other skin was created without the rib.

Cold-soaked fuel frost (CSFF) is a form of aircraft wing contamination that occurs when a vehicle caries sufficient fuel for multiple trips or take-offs and landings. Following the first trip, which may reach altitudes above 10,000 m (33,000 ft), the fuel for the subsequent trips is carried in the wing tanks and may reach temperatures below -25 °C. In certain times of the year at some airports, temperatures and humidity levels will form CSFF on the aircraft wing surfaces over the fuel tanks. Unless an exemption is granted for the specific aircraft model, aircraft are not allowed to takeoff if the wing surfaces are contaminated by frost. Because aircraft operators desire to minimize vehicle time spent at airports, aircraft manufacturers are expected to pursue designs that safely operate with CSFF at takeoff and to pursue certification exemptions for aircraft models enabling CSFF takeoffs.

During aircraft design and certification, in-flight ice accretions are simulated using ice prediction codes. LEWICE, the ice accretion prediction code developed by NASA, employs a time-stepping procedure coupled with a thermodynamic model to calculate the location, size and shape of an ice accretion. LEWICE has been extensively validated for a wide range of icing conditions. However, continuing improvements to LEWICE predictive capabilities require better understandings of 1) the fundamental physics of turbulent flow generated by ice accretion roughness during an icing event and 2) the mechanisms responsible for convective enhancement of real ice accretion roughness. Recent experiments in the Icing Research Tunnel (IRT) at NASA Glenn Research Center have enabled significant insights into the nature of ice accretion roughness spatial and temporal variations.