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-L agrangian-Eulerian method with an adaptive grid-generation scheme is used. Three nondinensional geometric parameters are studied: the length-to-diamet er ratio of the swirl chamber L-s/D-s and orifice l(0)/d(0) and the swirl-c hamber-diameter-to-exit-orifice-diameter ratio D-s/d(0). 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 a nd performance of simplex nozzles, With a constant mass flow through the no zzle over the range of parameters considered, an increase in L-s/D-s produc es 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 th e discharge coefficient. Conversely, increasing l(0)/d(0) decreases film th ickness, spray cone angle, and discharge coefficient. An increase in D-s/d( 0) results in a decrease in film thickness and discharge coefficient and a decrease in spray cone angle.