Improved Semiempirical Correlation to Predict Sauter Mean Diameter for Pressure-Swirl Atomizers

The Sauter mean diameter of pressure-swirl atomizers plays a critical role in combustors. The semiempirical correlations are extensively employed in the preliminary combustion design stage to estimate the Sauter mean diameter for combustors. However, few correlations are capable to reflect the effects of geometry on the Sauter mean diameter with satisfied accuracy. In this study, a semiempirical model improved from the surface wave breakup theory was established to predict Sauter mean diameter of pressure-swirl atomizers. Three geometric elements of atomizers, including tangential ports, swirl chamber, and discharge orifice, pose a significant effect on the Sauter mean diameter of pressure-swirl atomizers. The effects of the three geometric elements on Sauter mean diameter are included in the semiempirical correlation. Eighteen different pressure-swirl atomizers were employed in the experiment to verify the established model. Pressure-swirl atomizers are here investigated experimentally at supply pressures up to 12 bar. Water and kerosene were applied in the verification of the model. The uncertainty of prediction on the Sauter mean diameter is less than . The precision of improved semiempirical correlation was also verified with the experimental results from other literature. The improved semiempirical correlation is proved to be qualified for the optimization of existing pressure-swirl atomizers.