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In this study, spray behavior of bio-ethanol as a regenerative fuel that reduces emissions such as NOX and CO is investigated in a combustion chamber and compared to its different blends with gasoline. For this purpose, microscopic and macroscopic spray characteristics and also evaporated fuel mass after the injection are modeled and investigated using Fire 2013. It is concluded by increasing bio-ethanol content in the fuel, evaporated fuel mass, spray cone angle, spray area and sauter mean diameter increases, however spray tip penetration remains roughly constant. Increase of injection pressure, decreases spray cone angle and suater mean diameter and increases evaporated fuel mass, spray area and spray tip penetration. If the energy content and time of injection of bio-ethanol and gasoline be equivalent the results vary significantly compared to previous cases. In this case bio-ethanol has a longer spray tip penetration and spray area, higher fuel mass evaporated and smaller spray cone angle and sauter mean diameter compared to gasoline. The increased spray tip penetration and spray area in this case may lead to piston impingement and bore wetting resulting increased hydrocarbon emissions and decreasing engine efficiency.

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cost-effectiveness, and reliability. Despite numerous experimental studies on pressure-swirl atomizer spray, a comprehensive mathematical model for predicting spray characteristics has not yet been presented. Additionally, there is no consensus on the distribution function accurately describing droplet size dispersion. In the present study, the main characteristics of pressure-swirl atomizer spray, including discharge coefficient, spray cone angle and droplet size distribution, were experimentally investigated using the shadowgraph technique. The study spanned a wide range of Reynolds numbers, from 1250 to 8500, encompassing laminar, transition, and atomization regimes. The findings showed that the discharge coefficient initially declined during the transition stage, followed by a gradual increase up to the atomization regime. In the atomization regime, the discharge coefficient remained almost constant. A similar trend was observed for the spray cone angle throughout the transient and atomization phases. The gamma distribution function provided a favourable fit with the experimental drop size distribution in the near-ligament location, where primary breakup mechanisms dominate. The log-normal distribution function showed superior fitting with the experimental droplet size distribution for regions distant from the liquid sheet disintegration point, where secondary breakup mechanisms exert a more pronounced influence on droplet dispersion. Overall, these findings provide valuable insights into spray characteristics and associated uncertainties.