Fuel/Air Mixing in Reacting and Non-reacting Flows within a Dual-mode Combustor

Abstract

An experimental investigation on fuel and air mixing characteristics within a dual-mode combustor is presented. To determine the dominant parameters of mixing characteristics of fuel with airflow, fuel (H₂ or C₂H₄) or inert gas (He, N₂ or Ar) were perpendicularity injected from plural circular orifices into high- or room-temperature M2.5 airflows decelerated through pseudo-shockwave systems. Under similar dynamic pressure ratios, fuel mass flux contours downstream of the injector were similar between the H₂ and C₂H₄ reacting cases. However, fuel mass flux contours were different between the C₂H₄ reacting and Ar non-reacting cases due to the heat-release effect during local mixing. On the other hand, heat-release effect on mixing efficiency was found to be minor in bulk-scale mixing evaluation. It was found that C₂H₄ mixing efficiency with an equivalence ratio of 1.6 could be predicted within an error of a few percent from Ar mixing results under similar dynamic pressure ratio and similar peak pressure.