Evaluation of a Jet Fuel Thermal Stability Rig

Current and planned gas turbine engines use fuel as their primary heat sink. When jet fuel is thermally stressed it will form gums and deposits. These deposits can block engine fuel nozzles, causing damage to the engine hot sections, especially the combustor region. The fuels thermal stability is a critical fuel property with respect to optimum performance of modern military gas turbine engines. The current standard method to rate fuel thermal stability, the Jet Fuel Thermal Oxidation Tester (JFTOT), is a subjective, pass-fail type test and is not adequate as a tool to quantitatively investigate fuel thermal stability. This report describes a program to design, construct and commission a rig capable of quantifying fuels thermal stability based on carbon and sulphur deposit formation in a heated metal test tube. A fuel known to be unstable both chemically and thermally, sourced from RAAF Townsville, was used as a test fuel for commissioning the rig. The rig was found capable of discriminating between differing test conditions and was successful in rating fuels thermal stabilities based on quantification of the fuels deposit-forming capacities. A significant finding of commissioning procedures was the high levels of sulphur deposit formed in the test fuel