Experimental and theoretical investigations on spray characteristics of bio-ethanol blends using a direct injection system

In the present work, the spray characteristics of bio-ethanol and its blends have been experimentally and theoretically investigated. To have a comprehensive study, the effects of ambient condition and injection pressure on the spray of different blends have been considered. Macroscopic and microscopic characteristics of spray such as tip penetration length, cone angle, projected area, volume, Sauter Mean Diameter (SMD), and Ohnesorge number are investigated precisely. Besides, air entrainment and atomization analyses have been carried out to improve mixture formation process. Using curve fitting and least squares method, theoretical correlations have been suggested in such a way to predict experimental results with the accuracy of 9.9%. To have a good estimation of the calculated parameters, uncertainty analysis has been performed. The results demonstrate that enhancing the injection pressure or decreasing the ambient pressure improves the atomization characteristics of spray. Moreover, outcomes of this study indicate that spray tip penetration is enhanced by increasing the injection pressure or bio-ethanol percentage in the blend, while spray cone angle showing the opposite behavior.