Spray from a Bluff Body Combustor in Annular Air Flow

Abstract

Abstract-Non-combusting flow from a bluff-body combustor was studied. The combustor consisted of a cylinder centered in an annular air jet. Water was sprayed downstream from a poppet nozzle mounted in the downstream end of the cylinder. The air flow was seeded with titanium dioxide particles and then illuminated with laser light, as a means of visualizing the flow. Three lighting techniques were used: continuous sheetlighting, pulse sheetlighting, and pulse backlighting. The Reynolds numbers (based on hydraulic diameters) for the water flow ranged from 0 to 12,280; and for the air flow ranged from 0 to 90,400. The effects of varying air and water flow rate on the resulting axisymmetric flow field were recorded on film and videotape. Three general categories of flow structure were observed. In two of these categories, the effect of increasing air flow rate was to widen the dispersion of the spray. In the third category, the momentum flux of the water spray dominated pressure and drag effects of the air, resulting in a spray structure resembling that of a spray in still air. In this case, the air flow is strongly modified by the water spray.