Numerical and experimental study of the effects of tangential to axial velocity ratio and structural parameters inside the nozzle on spray characteristics

Pressure swirl nozzles are widely applied in spray cooling, dust removal, and fuel injection. To better connect the nozzle structure with the internal flow to analyze their influence on spray parameters, this paper designs a nozzle structure and uses experimental measurement and computational fluid dynamics simulation methods to investigate the influence of the nozzle's tangential velocity to axial velocity ratio (vτin/vzin) and the swirl diversion channel eccentric distance (dl) on the spray parameters. A phase Doppler particle analyzer was used in the experiment study to determine the spray axial velocity (vz) and sault mean diameter (D32). In the simulation investigation, the Eulerian multiphase flow model was used to calculate the multiphase flow field of the spray. The results showed that dl and vτin/vzin both have an obviously linear relationship to the peak location (rpeak) of each spray parameter. It means that dl plays similar roles as the vτin/vzin, which can enhance the swirl strength inside the nozzle and increase the spray cone angle. The rpeak of liquid phase volume fraction (αw) and D32 of the droplet particle are always greater than the rpeak of vz. The analysis of the flow field inside the spray orifice indicates that as the vτin/vzin rises, the liquid in the nozzle orifice tends to move farther from the central axis, causing atomization to occur more upstream. This study serves as a reference for the flow analysis and structure design of the pressure swirl nozzle.