1 Schlieren Imaging of a Single-Ejector, Multi-Tube Pulsed Detonation Engine

Single-ejector, multi-tube pulsed detonation engine configurations are examined utilizing high speed schlieren and coherent structural velocimetry. The mechanisms of ejector augmentation are evident in secondary air entrainment and induced flow across the ejector lip. An axisymmetric ejector with both a linear array and a more compact box array of detonation tubes was examined. Good secondary entrainment and subsequent ejector flow was observed, supporting previous results indicating off-axis effects are relatively insignificant to ejector thrust augmentation. A linear ejector with linear detonation tubes revealed limited secondary flow engagement with the ejector lip, likely due to structural ribs. Nomenclature d driver diameter Dej ejector diameter D*ej ejector equivalent-area diameter (2-D ejector) φ equivalence ratio ff fill fraction Hej ejector throat height (2-D ejector) igd ignition delay- time between valve closing and spark deposit Lej ejector length pf purge fraction Rin ejector inlet radius W ejector width (2-D ejector) x ejector distance downstream from detonation tube exit y distance from detonation tube centerlin