Numerical Study on Spray Evaporation Characteristics of SAFs and Jet A at Elevated Ambient Temperatures

Abstract

Understanding the spray characteristics of sustainable aviation fuels (SAFs) is crucial to their safe and efficient utilization. This study employs large-eddy simulations (LES) to investigate the spray and preferential evaporation characteristics of two SAFs and one conventional aviation fuel (Jet A) injected into a combustion chamber via a single-hole injector. The two selected SAFs are hydroprocessed esters and fatty acids (HEFA) and alcohol-to-jet (ATJ) synthetic biofuel, which have distinct component and physical properties compared to Jet A. Two chamber temperatures (473 and 573 K) are considered to investigate fuel effects under weak and strong evaporation conditions. The results show that both SAFs exhibit spray behaviors similar to those of Jet A at 473 K. However, at 573 K, ATJ exhibits the shortest penetration length due to its high proportion of low-boiling-point components, while HEFA shows a much longer penetration. A strong preferential evaporation effect is observed for all fuels at both temperatures, with greater impact on vapor component distribution at low temperatures but on droplet composition at high temperatures. Notably, the distillation curve alone fails to predict the penetration length differences among the fuels. These results suggest that the volatility distribution of fuel components, i.e., the relative proportions of low-, intermediate-, and high-boiling components, plays a significant role in determining spray behavior, particularly at high temperatures.