Computational Model of the Freezing of Jet Fuel

A computational fluid dynamics model is developed that simulates the solidification of jet fuel due to freezing in a buoyancy-driven flow. Flow resistance caused by porous crystal structures that exist in liquid-solid regions is simulated through the use of a momentum resistance source term. Experiments are performed in which jet fuel samples are cooled below their pour point temperatures in an optical cell. Polarized light is used to record images during the freezing process. In addition, low-temperature properties of jet fuel samples are determined, using a differential scanning calorimeter, pycnometer, and a low-temperature viscometer. The validity of the simulations is demonstrated by comparing temperature and solid area measurements with predicted values for various thermal boundary conditions and fuel samples. Reasonable agreement between experiments and simulations is obtained. Thus, the modeling technique is useful for aircraft fuel system designers in the prediction of fuel tank hold-up.