Thermal Effects on Fuel Injection in a Swirl-Stabilized Gas Turbine Combustor

Improvements in the thrust to weight ratio of future high performance air breathing combustion systems require operation at higher combustor temperatures and pressures prompting the need for increased understanding of the effects of thermal conditions on fuel combustion. The use of larger operating ranges requires extended understanding of fuel injection up to the transcritical and supercritical thermodynamic states. This paper describes an experimental study of the effect of fuel temperature on combustion characteristics using nGimat’s proprietary fuel injector in a swirl-stabilized combustor operating at atmospheric pressure. Measurements taken in the transcritical and supercritical regime for Jet-A fuel provided clear trends on emission levels as the fuel exposure to heat was increased. CO emissions decreased as fuel exposure to heat increased, with an opposite trend observed for NO x levels. Gas chromatography/mass spectroscopy analysis was used to determine the gaseous and liquid products for the conditions investigated. Droplet diameter and velocity were determined in the near-injector region using a two-component Phase Doppler Particle Analyzer to examine the Jet-A spray characteristics in the low-pressure environment.