Dual-mode scramjet control using optical emission sensors

Closed-loop fueling control of a dual-mode scramjet was successfully demonstrated using optical emission spectroscopy as the sole sensor for controller feedback. The optical emission from species of interest (OH ∗ , CH ∗ , C 2 ∗ ) was first characterized throughout the combustor. The relative emission intensity between species pairs was studied over a range of fueling conditions and imaging locations throughout a dual-mode scramjet combustor flow path. The pair of emissive species (C 2 ∗ /OH ∗ ) and imaging location that were the most sensitive to changes in fueling condition were selected for use in the control system. Changes in optical transmission of the observation windows and the impact on fuel control were explored. To our knowledge, this paper is the first demonstration of fueling control of a dual-mode scramjet using only optical emission spectroscopy as feedback.