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A Study of Acoustic Forcing on Gas Centered Swirl Coaxial Reacting Flows (Conference Paper with Briefing Charts)

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Conference Paper

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Air Force Research Laboratory (AFMC) AFRL/RQRC Edwards AFB United States

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The reacting flow from a single gas-centered, swirl-coaxial injector was studied in an optically accessible, high-pressure chamber, with and without high-frequency acoustic perturbations. The gas-centered, swirl-coaxial injector employed liquid rocket engine relevant propellants of gaseous oxygen and RP-2. The reacting flow field behavior at an operating chamber pressure of 3.2 MPa and varying momentum flux ratios were investigated. High-speed shadowgraph images along with OH and CH chemiluminescence images were taken to capture the liquid fuel film, droplets, and flame response under acoustic excitation. For the acoustic forcing studies, low amplitude transverse standing waves typically below 5 of the chamber pressure were generated to simulate transverse combustion instabilities. Proper orthogonal decomposition and dynamic mode decomposition were performed on the high-speed shadowgraph and chemiluminescence images to detect the flame response to acoustic forcing, to which in-plane flapping motion was observed for acoustic forcing and rotating soot clouds were a large structures associated with the reacting flow field.

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  • Fluid Mechanics

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