Experimental Investigations of Effects of Venturi Angle on the Spray Structure

In this paper, the spray characteristics of a double-swirl low-emission combustor are analysed by using PIV and PLIF technologies in an optical three-sector combustor test rig. The interactions between sectors and the influence of venturi angle on spray structure are explained. The results illustrate that the flow field plays a decisive role in the forming of spray structure. The interactions between sectors make the differences of flow field and spray structure between sectors. The venturi angle has a great influence on the spray structure and interactions between sectors. In a word, the results of the mechanism of spray organization in this study can be used to support the design of new low-emission combustor. INTRODUCTION There is an urgent need of improving combustion efficiency and decreasing emission pollution with the increase of stringent regulations on pollutant emissions [1, 2]. Nowadays, in order to improve the fuel atomization performance and reduce pollution, fuel-staged partially premixed combustors are applied. The combustor consists of pilot stage and main stage. The pilot stage adopts diffusion combustion to improve the ignition and the main stage adopts partially premixed combustion to improve combustion efficiency, avoid hot streak and reduce pollution emission. Air-blast nozzle is commonly used in low-emission combustor, in which the flow field organization and the spray organization determine the combustion efficiency and temperature distribution. Innovative designs for coping with operability and future regulations on pollution emissions has been done by a lot of researchers. Swirl cup combustors basing on swirl-stabilized combustion have been applied extensively to modern aero engine combustors because of the excellent combustion performance[3]. Hence, many researchers have carried out a lot of studies on the flow field, spray and combustion performance of swirl cup combustors. Wang et al., Fu et al., and Colby et al. studied the effects of geometry parameters on the flow field and spray, including flare geometry, confinement, and swirl angle et [4-7]. Ateshkadi et al.[8] studied the effect of swirl vane angle, swirl sense and venturi on LBO performance, and a new LBO correlation model accounting for heterogeneous reaction and geometry of mixer component is developed. Ateshkadi[5] and Mongia[9]