| The turbine of any engine is responsible for power generation and any damages to this component can result in significant degradations in performance. Highly non-uniform temperature distributions at the exit of a combustion chamber can lead to thermal stressing of the nozzle guide vanes and first stage turbine blades causing erosion or cracks requiring extensive maintenance and increased operational down-time. To investigate the effects of fuel nozzle condition on exit temperature profiles, an optical patternator was used to examine spray patterns for differences in spray cone angle, symmetry, and fuel streaks. An ambient pressure and temperature rig constructed with Allison/Rolls Royce T56-A-15 gas turbine engine components was used to capture the exit temperature distributions. Rig tests simulated representative engine operating conditions by matching Mach Number, equivalence ratio, and droplet size (D 32).;The main conclusion of this research was that small deviations in the fuel nozzle spray pattern from a nominal distribution correlated to an increase in pattern factor. Reductions in the spray cone angle, increased variations in spray roundness and increased streak intensities resulted in a degradation of the mixing processes, which created large regions of very high temperature core flow and smaller regions of cooler temperatures within the combustion chamber exit plane, subjecting the nozzle guide vanes and turbine blades to hotter temperatures at their roots and tips. The spray cone angle had the most measurable influence, with a 10% decrease resulting in a 15% rise in pattern factor. The effects of spray roundness and streak intensity had slightly less influence on pattern factor. The results of this research were compared to past studies and the pattern factors were representative of the typical values expected for a T56-A-15 combustion chamber. Recommendations for future testing of fuel nozzle condition are made in this work. |
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