Influence of convergence angle on hollow cone spray characteristics

Abstract

Simplex atomizer (Pressure swirl atomizer) is widely used in liquid rocket engines and gas turbines because of its enhanced atomization characteristics. In a simplex atomizer, swirling motion is imparted to the liquid by the tangential entry of the fuel. In turn, a hollow cone fuel spray is produced from the orifice under the action of centrifugal force. Liquid properties, injection flow conditions and atomizer geometry govern the performance of an atomizer. Thus, it is very important to study the effects of these parameters, for optimizing the spray characteristics in terms of the drop sizes and spray cone angle. The swirl chamber convergence angle (?C) is one of the most important parameters which affects the injector performance. Very few researchers have focused on this aspect. In this paper, an experimental parametric analysis is performed to investigate the effect of swirl chamber convergence angle on the performance of simplex atomizer and the characteristics of the hollow conical liquid jet exiting the nozzle. Four different simplex atomizers with varying convergence angle (30°, 45°, 60° and 75°) are used for the experimental study. All other geometrical parameters are kept the same. The atomization behaviour which includes spray cone angle, co-efficient of discharge, Sauter mean diameter (SMD) and drop size distribution is analyzed at various radial locations by using a high-speed camera and Phase Doppler Interferometer (PDI). Experiments are carried out at different pressures ranging from 0 to 7 bar to characterize the atomizer performance at different operating conditions.