Experimental evaluation of low pressure-swirl atomizer applied engineering design procedure

Abstract

In a pressure-swirl atomizer a swirling motion is imparted to the fuel leading it, under the action of centrifugal forces, to spread out in the shape of a hollow cone as soon as it leaves the exit orifice. This kind of atomizer is used in gas turbines and liquid-propellant rockets. The need to minimize the combustor length usually leads to spray angles around 90 deg. The present work presents a procedure to design and verify the experimental behavior for low pressure-swirl atomizers. This atomization condition is especially important, for example, in the case of gas turbine operation under idle regime. The Sauter mean diameter and the spray-cone angle are evaluated and made to fit the calculated atomizer dimensions. The Sauter mean diameter is obtained through the use of a model originally developed for fan-spray atomizers and extended for pressure-swirl atomizers. A pressure-swirl atomizer was manufactured following this design procedure. The discharge coefficient, the spray-cone angle, and the Sauter mean diameter were evaluated experimentally and compared with the theory used to design the atomizer displaying a good matching. The spray Sauter mean diameter was measured with a laser scattering system. Copyright © 2008 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.