A comprehensive model to predict simplex atomizer performance

The pressure swirl atomizer, of simplex atomizer, is widely used in liquid fuel combustion devices in the aerospace and power generation industries. A computational, experimental, and theoretical study was conducted to predic t its performance. The Arbitrary-Lagrangian-Eulerian method with a finite-v olume scheme is employed in the CFD model. Internal flow characteristics of the simplex atomizer, as well as its performance parameters such as discha rge coefficient, spray angle and film thickness, are predicted. A temporal linear stability analysis is performed for cylindrical liquid sheets under three-dimensional disturbances. The model incorporates the swirling velocit y component, finite film thickness and radius that are essential features o f conical liquid sheets emanating from simplex atomizers. It is observed th at the relative velocity between the liquid and gas phases, density ratio a nd surface curvature enhance the interfacial aerodynamic instability. The c ombination of axial and swirling velocity components is more effective than only the axial component for disintegration of liquid sheet. For both larg e and small-scale fuel nozzles, mean droplet sizes are predicted based on t he linear stability analysts and the proposed breakup model. The prediction s agree well with experimental data at both large and small scale.