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

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 air fl ow, fuel (H 2 or C 2 H 4 ) or inert gas (He, N 2 or Ar) were perpendicularity injected from plural circular ori fi ces into high- or room-temperature M2.5 air fl ows decelerated through pseudo-shockwave systems. Under similar dynamic pressure ratios, fuel mass fl ux contours downstream of the injector were similar between the H 2 and C 2 H 4 reacting cases. However, fuel mass fl ux contours were di ff erent between the C 2 H 4 reacting and Ar non-reacting cases due to the heat-release e ff ect during local mixing. On the other hand, heat-release e ff ect on mixing e ffi ciency was found to be minor in bulk-scale mixing evaluation. It was found that C 2 H 4 mixing e ffi ciency 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.