Parametric Study of Simplex Fuel Nozzle Internal Flow and Performance

A numerical study is presented of the effects of changes in simplex nozzle geometry on its performance. A computational model based on the arbitrary-Lagrangian-Eulerian method with an adaptive grid-generation scheme is used. Three nondimensional geometric parameters are studied: the length-to-diameter ratio of the swirl chamber [L.sub.s]/[D.sub.s] and orifice [l.sub.o]/[d.sub.o] and the swirl-chamber-diameter-to-exit-orifice-diameter ratio [D.sub.s]/[d.sub.o]. The variations in the atomizer performance, caused by the changes in the geometric parameters, are presented in terms of the film thickness at the exit of the orifice, the spray cone angle, and the discharge coefficient. Results indicate that these geometric parameters have a significant effect on the internal flow and performance of simplex nozzles. With a constant mass flow through the nozzle over the range of parameters considered, an increase in [L.sub.s]/[D.sub.s] produces an increase in the film thickness at the orifice exit, a decrease in the spray cone half-angle, and a slight decrease followed by an increase in the discharge coefficient. Conversely, increasing [l.sub.o]/[d.sub.o] decreases film thickness, spray cone angle, and discharge coefficient. An increase in [D.sub.s]/[d.sub.o] results in a decrease in film thickness and discharge coefficient and a decrease in spray cone angle.