Açık uçlu basınç girdaplı püskürteçlerin akış analizi

In this study, high-fidelity 3D and 2D axisymmetric open-end pressure swirl atomizer CFD simulations were performed. The low Reynolds number multiphase liquid flow is captured with the VOF method and second-order accurate direct solution of the incompressible Navier-Stokes equations (Quasi-DNS). The study aims to investigate the internal flow characteristics of PSA without inlet and contraction effects. Because in PSA, swirling liquid film flow is generated with a finite number of tangential inlet ports. These ports generate jet flows, which are one of the leading reasons for flow instabilities in liquid film. These instabilities are the results of spray non-uniformity in PSA. To remove these effects, continuous ring-like axisymmetric inlet surface and axial inlet surface with liquid film tangential, axial velocity, and VOF profile are used in 3D simulations. The VOF and velocity profiles are obtained from the swirling liquid film of ring-like inlet PSA simulations. In ring-like inlet simulations, Görtler vortices are captured within the liquid film and obtained that the instability source of these vortices is flow separation near the inlet. Development of Görtler vortices without referred instability source is examined in 3D axial inlet PSA simulations. Conclude that Görtler vortices initiate itself even without inlet separation. Görtler number is computed in the swirling liquid film to compare the results obtained with those in the literature. The Görtler number is modified which will be suitable for two-phase swirling film flow. After that, the effect of Görtler vortices on liquid film and spray is examined. The development of velocity profiles of liquid film through the exit of PSA is compared with 2D axisymmetric simulations, and Görtler vortices are observed to result in a linear velocity profile in film. However, it does not affect PSA's performance parameters. The pressure drop, film thickness, and spray angle of 2D axisymmetric simulations are predicted to be almost the same as those of 3D simulations. In the scope of these results, a new blade-type inlet for PSA is designed. By utilizing the inlet type, uniform flow at the inlet is achieved. Due to the achievement, the PSA swirl atomizer can be accurately designed by utilizing 2D axisymmetric simulations, which are remarkably faster than 3D simulations. An experimental study was conducted to examine the performance of blade-type inlet PSA. The results of the experiments are compared with the 3D and 2D axisymmetric simulations.