Prediction of gas-solid nozzle performance based on CFD and response surface methodology

In this work, structural parameters and performance prediction of fan nozzles for powder spraying are investigated. Computational Fluid Dynamics (CFD) was used to simulate the working process of the grooved fan nozzle. A Box-Behnken experimental model was developed to analyze the effects of the structural parameters on the nozzle air flow stability and working performance, taking the nozzle structural parameter contraction angle (alpha), the ratio of outlet to inlet diameter (d/D), the ratio of outlet diameter to length (L2/d), and the half angle of the "V"- shaped groove (beta). The air flow stability and working performance of nozzle were evaluated through coefficient of variation (Cv) and standard deviation (SD). Using multiple regression analysis, the prediction model of Cv and SD on the structural parameters is established. It was obtained that: with the increase of the diameter and length of the nozzle outlet, the spray angle of the nozzle decreases. As the "V"- shaped groove angle increases, the powder spray angle decreases. The effects of structural parameters on Cv are d/D, alpha, beta, and L2/d in ascending order, and on SD are d/D, alpha, beta, and L2/d in ascending order. In addition, the influence of the interaction of each structural parameter on Cv and SD was obtained. This study can provide a reference for the design and structural optimization of fan nozzles for powder spraying.