Design and Measurement of Injection Gas Concertation in Rotating Detonation Engines via Diode Laser Sensors

Abstract

For an air-breathing rotating detonation engine (RDE), in practice a relatively low drop of stagnation pressure of combustor and lower losses from air injection/inlet are desirable. A 6 inch diameter RDE running with pressure ratio cross air injection around and less than chocked condition was developed and examined to investigate its operating characteristics. Further, design and measurement of fuel concertation ahead of and downstream the injection surface are being undertaken via tunable diode laser absorption spectroscopy (TDLAS) technique. Experimental results show that the ethylene/air RDE can be operational even though the injection pressure ratio is lower than chocked condition. The TDLAS system was designed to apply Md-IR (3.411 μm) and Near-IR (1.625 μm) diode lasers to scan absorption features of ethylene and CO₂ of the product gas, respectively. From these results, one could have a better understanding on local equivalent ratios and their distribution immediately before the arrival of the rotating detonation and study whether the product gas would flow back to the air plenum and their effects on RDE performance, in particular for the engines operating at the relatively low injection pressure ratio. This part of work is being tested and will be reported in the presentation.