Fuel Spray and Operating Condition Impact on Ignition Performance in the ARC-M1 Combustor

In the interest of developing small-scale gas turbine combustors, understanding liquid fuel spray effects on global combustion ignition performance is critical. In these experiments, baseline ignition performance behavior is established for a relatively small-scale gas turbine combustor operating at cold-start and altitude ignition conditions. Additionally, ignition tests at cold-start conditions are conducted using multiple fuel spray nozzles to evaluate the effects of fuel spray behavior on global ignition probability performance. The combustor used for these experiments, the ARC-M1, was developed in conjunction with engine OEMs and replicates key geometric features of helicopter-size gas turbine combustors while offering convenient optical access. Baseline ignition performance measurements are conducted using an altitude chamber at near-sea level pressure (92.5 kPa) at three temperatures (15 °C,-10 °C, and-35 °C) and at altitude conditions corresponding to 10,000 ft elevation (69.4 kPa,-5 °C). Ignition measurements comparing fuel spray nozzles are conducted outside of the altitude chamber at cold-start inlet conditions (-5 °C & 25 °C, 103 kPa). Results demonstrate strong temperature and pressure effects on performance in the combustor, with both low temperature and low pressure conditions severely degrading performance. Comparisons between fuel nozzles show a major shift in the equivalence ratios that demonstrate ignition performance compared to the reference nozzle. The knowledge gained from this study will help direct gas turbine ignition modeling efforts and detailed experiments on this combustor investigating fuel spray effects on ignition performance and inform future small-scale combustor design.