A novel plasma heater for auto-ignition studies of turbulent non-premixed flows

In this paper, the development and characterization of a novel test rig for auto-ignition (AI) studies of a fuel jet propagating into a hot turbulent co-flow is reported. The test rig, based on microwave plasma heating, is capable of achieving co-flow temperatures up to 1300 K and velocities up to 40 \(\hbox {ms}^{-1}\). Important boundary conditions at nozzle exit such as temperature, species, and velocity field were determined to prove the capabilities and limitations of the test rig. Liftoff height (LOH) measurements of \(\hbox {CH}_4\), \(\hbox {C}_2\hbox {H}_4\), and \(\hbox {CH}_{4}/\hbox {H}_{2}\) jets, propagating into a turbulent heated air co-flow, were taken using chemiluminescence imaging. Effects of the temperature and Reynolds number (Re) of co-flow and jet were also studied. Results showed that the flame stabilization mechanism is supported substantially by AI rather than pure flame propagation. While the co-flow temperature dominates the AI process, the Re and temperature of the jet just have a small impact on the LOH.