GT2004-53524 Experimental investigation of spatial and temporal aspects of the liquid fuel placement in a swirl cup at elevated pressure

Abstract

The kerosene spray generated by a pressure swirl fuel nozzle embedded in a swirling airflow in a swirl cup typical of aeroengine combustors was investigated at different levels of air pressure to assess the counter-acting effects of increasing air density and transfer of centrifugal momentum from airflow to spray. Hardware parameters investigated included air swirl angle and fuel nozzle flow number. Measurement techniques included spray visualization, Phase-Doppler Anemometry (PDA) for spray analysis and Laser-Doppler Anemometry (LDA) for investigation of the air flow field. Operating conditions for PDA measurements were 6, 12, and 18 bar at 700 K. Spray visualizations and LDA measurements were performed at scaled operating conditions. It was found that fuel placement is governed by the presence or absence of a recirculation zone inside the swirl cup and hence by the swirl angle of the airflow. Analysis of temporal aspects of the spray showed the existence of droplet clusters. Configurations characterized by strong swirl furthermore exhibited a preferred frequency of inter-particle times.