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Atomization and Sprays, Vol.26, No.5, 483-511, 2016
REVIEW OF FUEL SPRAY DISTRIBUTIONS TO PREDICT PERFORMANCE OF ROTARY ATOMIZERS IN A SLINGER GAS TURBINE COMBUSTOR
A research program was pursued on a rotary fuel nozzle commonly called a "slinger" atomizer for gas turbine application in order to characterize its spray distribution. The main advantage to be expected from this type of nozzle is a more uniform spray distribution leading to a more evenly distributed exit temperature at the combustor exit, thus providing a longer turbine life. In the course of this project, an in-depth open literature review was completed on rotary atomizers to find suitable correlations for an adequate spray distribution to eventually validate computational fluid dynamics (CFD) simulations to assess various potential injector configurations. After a substantial review of available correlations for the most promising types of rotary atomizers, i.e., flat disks, and plain (unperforated) and perforated cups, many uncertainties and inconsistencies were observed between reported test results and generated correlations to predict the average droplet size and a Rosin-Rammler spray distribution. A significant effort was devoted to validate and compare these found correlations in relation to their range of validity, to the flow regime, and to the measurement method for droplet diameters which showed as the most significant unknown parameters leading researchers to generate unreliable correlations. Ultimately after a thorough analysis, when comparing these three types of rotary atomizers for a given geometry and operating conditions, corresponding to a small typical gas turbine, the smallest SMD (based on idle condition) is achieved by the perforated cup operating in supercritical film mode, followed very closely by the plain cup, the flat disk, and the perforated cup operating in subcritical mode.
Keywords:spray distribution;rotary atomizer;slinger;Rosin-Rammler;liquid atomization;small gas turbines;breakup regime;rotating cup;perforated disk;centrifugal atomizer