Nonreacting Spray Characteristics for Alternative Aviation Fuels at Near-Lean Blowout Conditions

The spray characteristics of standard and alternative aviation fuels generated by a hybrid pressure-swirl airblast atomizer were studied at conditions corresponding to near-lean blowout conditions: ambient gas pressure Pvessel=2.07bar, fuel temperature Tfuel=322K, and atomizing gas temperature Tgas=394K. The candidate alternative fuels (C-1, C-5, C-7, and, C-8 synthetic blends) were compared to Jet-A (A-2). The drop size and drop velocity were measured using phase Doppler anemometry at three measurement planes downstream of the swirler exit. The representative diameters [D10, D32, and the mass mean diameter (MMD)] were used to characterize the drop size. The drop velocity was characterized using the arithmetic mean and the root mean square. An increase in the swirler pressure drop (Delta P/P) showed a decrease in the mean drop size and an increase in the magnitude of the axial drop velocity. Comparing the different fuels generally showed an increase in D10 for higher fuel viscosity. However, definitive trends in D32 and the MMD were not observed, based on fuel physical properties such as viscosity, surface tension, or density. A variation of the fuel injection pressure Delta PPilot showed no significant effect for both the standard and alternative fuels. The full cone angle (obtained using shadowgraph images) was found to not vary significantly with Delta PPilot or Delta P/P.