Experimental Study of Spray Characteristics at Cold Start and Elevated Ambient Pressure using Hybrid Airblast Pressure-Swirl Atomizer

摘要

Alternative aviation fuels are of great interest to the aviation industry due to their economic and environmental benefits. The presented work focuses on an experimental study of spray characteristics of standard and alternative aviation fuels at cold start conditions using a hybrid airblast pressure-swirl atomizer. Two standard aviation fuels and one alternative fuel were selected for these measurements: Jet-A (A-2), JP-5 (A-3), and a JP-5/farnesane blend (C-3). Phase Doppler anemometry (PDA) was used to measure the drop size and drop velocity of the fuel spray at multiple axial locations downstream of the swirler exit at cold start conditions. The cold start conditions included an ambient gas pressure (P_(vesSel)) of 1.01 bar, and a fuel temperature (T_(fuel)) and atomizing gas temperature (T_(gas)) of 239 K. The pressure drop across the swirler of the atomizer (△P/P) was varied in order to investigate the effect on the spray characteristics. The representative diameters, D_(10), D_(32), and MMD, were used to characterize the mean drop size. The mean axial drop velocity (U_z) along with its root-mean square deviation were used to characterize drop velocity. The cold start investigation showed that the mean drop diameters decreased with increasing AP/P for all fuels. No significant variation in mean drop diameters and velocities was observed for the different fuels at the same operating conditions. The results of an investigation of the influence of elevated ambient pressure on the spray characteristics for Jet-A are also presented. An increase in ambient pressure decreased the mean drop size initially. Then the mean drop size started to increase, but only slightly, with further increase in ambient pressure.