A fast-response flame ionization detector (FFID) has been used to study isothermal gas transport and mixing inside a gas turbine combustion chamber. The large, highly linear dynamic range of the FFID coupled with a frequency response that extends up to approximately 200 Hz can reveal large-scale features of interest in turbulent flows. Experiments were performed in a ground-based test facility simulating high-altitude restart conditions. Pulses of propane were discharged into the core swirler of a fuel injector through a high-speed valve. The mole fraction of this tracer was monitored at various locations inside the combustion chamber. These measurements allowed the identification of recirculation timescales and flow instabilities at different points inside the combustion chamber, providing important insights into the altitude restart process.
Keyword: Gas turbine,Residence time,Flame ionization detector,Altitude relight