Prediction of Fuel Freezing in Airplane Fuel Tanks of Arbitrary Geometry — Part 2 Available to Purchase

Cooldown of fuel inside a horizontal cylinder (i.d. approximately equal to that of a pylon tank) was modelled with a mixture of 50% glycerine and 50% water (Ti = 65°C). Safety considerations and poor optical qualities at low temperatures precluded fuel from being used in these experiments. The test was started by suddenly imposing a nominal 10°C external temperature field (flowing tap water) on the aluminium skin. Fluid velocities and temperatures were measured during the transient near the mid‐length plane of the cylinder, where end effects were reduced. Therefore, the physical situation at this plane was considered amenable to a 2‐D analysis. Tests were conducted with a full partially full tank and included tests with the tank tilted 10° from the horizontal to determine axial convection effects; this angle approximates an angle of attack during cruise. Tilting the tank produced temperatures at the elevated end which were significantly higher than those at the lowered end, especially for the bottom ½ of the tank where the ΔT between ends was as high as 5°C 30 minutes after the start of test.