Investigation of deposition in aviation gas turbine fuel nozzles by coupling of experimental data and heat transfer calculations

Fuel deposition in gas turbine nozzles is a problem that needs to be avoided, and for this reason many studies concerned with either experimental or Computational Fluid Dynamics methodologies for the investigation of deposition are being carried out. In this work, a Radio Frequency heated tube design is employed with the Aviation Fuel Thermal Stability Test Unit facility in which three sets of thermocouples are installed at different depths along a straight tube. Using thermocouple measurements and heat transfer calculations based on the locations of these thermocouples allowed for the generation of data such as radial heat transfer, deposition thickness, deposition thickness growth rate, and total deposit volume for each instant of the logged measurements. Deposition experiments were carried out with varying initial wall temperature and fuel inlet temperature, and it was observed that the most important parameter for deposition growth is the initial wall temperature rather than the fuel inlet. Furthermore, it was shown that as deposition forms, the total heat transfer from the tube wall to the fuel remained the same. In addition to this, a shift of heat transfer from the tube outlet towards the tube inlet was observed where the deposition was less.