Analysis of large scale thermal stability testing

The results of thermal stability testing on the Aviation Fuel Thermal Stability Test Unit (AFTSTU) are compared for a range of fuels. Common features in the resultant data have allowed the fitting of data for the temperature rise in a representative burner feed arm tube over the course of the test at various different heat loadings to an empirical relationship. This relationship is of a similar form to that seen in transient heat transfer calculations. Testing of the same fuels has also undertaken using the High Reynolds Number Thermal Stability (HiReTS) rig, both in the EI 482 form and in an adapted mode to represent more closely the AFTSTU test conditions, albeit at a smaller scale. A similar empirical relationship is observed and permits some discussion around the scaling of representative burner feed arm deposition. However, unlike the AFTSTU the HiReTS test provides no other information on the engine fuel system's sensitivity to fuel thermal stability. The adapted HiReTS test is not considered suitable to replace AFTSTU testing; however initial screening work on a smaller scale is attractive in the assessment of the suitability of alternative fuels. The use of an adapted test allows smaller scale thermal stability tests to be carried out on novel and alternative fuels without the need for large volumes of fuel and permits a prediction of their large-scale performance.