High speed shadowgraphy of a combusting atomizer spray at elevated pressure

Abstract

This contribution demonstrates the use of a compact high repetition rate pulsed high power LED light source in combination with a high speed camera to obtain high speed shadowgraphs of an airblasted spray in a fired research combustor at medium pressures. The temporally resolved structures are subjected to conventional spectral analysis and exhibit very dominant fundamental frequencies throughout the visualized spray structures. The image data is further compared to time series of drop-sizing measurements made by a phase Doppler instrument. The periodicity is attributed to a spiraling spray release from the nozzle lip that is believed to be induced by a precessing vortex or vortices orbiting around the burner axis. The logical extension of the technique is to use multiple views to obtain different views of the spray simultaneously. Photogrammetric or tomographic reconstruction techniques then allow the spray to be reconstructed three-dimensionally. The technique is demonstrated on a water spray nozzle.