Computational and Experimental Study of Liquid Sheet Emanating from Simplex Fuel Nozzle

A computational model for flow in a simplex nozzle has been established to predict the characteristics of the liquid sheet emanating from it. An important aspect of the numerical method is the accurate tracking of the liquid/gas interface. Because the interface geometry is not known a priori, it must be determined as part of the solution. The arbitrary-Lagrangian-Eulerian numerical method with finite volume formulation was employed for this purpose. To validate the computational and numerical modeling, experiments have been conducted on a large-scale nozzle using flow visualization techniques. The gas/liquid interface locations inside the nozzle, as well as just downstream of the orifice, have been determined for a range of mass flow rates and injector geometries. Using these measurements, the liquid film thickness and angle of the liquid sheet has been determined. Comparisons of the computational predictions with the experimental measurements show excellent agreement. Results indicate that the current theoretical correlations based on inviscid flow assumptions underestimate the film thickness and overestimate the spray angle significantly in large scale nozzles. It was found that an increase in the atomizer constant K [xAp/(D m d o )] results in decreasing the spray angle and increasing the liquid film thickness, where Ap is the total swirl slot area, D m is the effective spin chamber diameter, and d o is the orifice diameter. The discharge coefficient also increases with the atomizer constant.