Experimental study on the accretion and release of ice in aviation jet fuel
Ice formations in aircraft fuel systems pose a serious safety threat with potentially disastrous consequences, when restricting the fuel flow towards the engines. This is an ongoing challenge in the aerospace industry. In this work experimental studies have been performed to investigate the effects of temperature, flow rate and surface properties on the accretion and release of ice in flowing fuel. A test rig with a glass-windowed pipe has been employed to quantitatively measure the transient icing process under controlled conditions. The accreted ice exhibited soft and fluffy characteristics and was most likely the result of impinging solid ice particles that were entrained in the fuel flow. The ice particles were most sticky in a temperature range between −6°C and −20°C. The thickness of accreted ice decreased with roughness on aluminium surfaces and there was a significant reduction on polytetrafluoroethylene (PTFE) and polymethyl methacrylate (PMMA) in comparison to aluminium, copper or stainless steel surfaces. Comparison of the thickness of accreted ice with the ice adhesion strength reported in the literature showed a clear correlation. The experimental results will help to gain better understanding of the ice accretion process in flowing fuel and may serve as basis for design guidelines to minimize ice formation within an aircraft fuel system.