Ice accretion measurements of Jet A-1 in aircraft fuel lines

Abstract

Ice accretion and blockages in aircraft fuel systems continue to be of interest as a result of their influence on system design and alternative fuel synthesis as well as their role in aviation incidents and accidents. Ice accumulation tests are performed in a recirculating fuel system with Jet A-1 fuel. Removable stainless steel test pipes and variable flow rates allow for the examination of ice accretion with variation of pipe diameter and Reynolds number in a repeatable manner. The flow loop is installed in an altitude chamber capable of −50 °C and the experiments involve full-scale flow components. Temperature of the flow loop is controlled with an initial −11 °C/h cooling rate followed by a constant temperature test time. Instantaneous measurements of pressure drop along the test pipe are used to characterize ice accretion. Additionally, end-view imaging of the test pipes is performed to characterize the size and quality of the accreted ice. Normalized pressure drop is seen to increase nearly linearly with time for the range of Reynolds numbers and temperatures tested. Approximate ice accretion rates are extracted from the time varying pressure drops assuming the ice accumulation changes the pipe surface roughness. Accreted ice layer growth rates as high as 0.91±0.12 mm/hr are seen at low flow rate conditions (Re∼4000, −10.5 °C) and decrease with increasing Reynolds number. Growth rates at −7 °C and −19 °C are ∼25% and ∼1.5% of the −10.5 °C growth rate, respectively, and follow the same Reynolds number trend.