Impact of the jet velocity on the turbulent liquid jet

Abstract

This numerical study aims to investigate the impact of jet velocity and nozzle diameter on liquid turbulent jet. Incompressible large eddy simulations (LES) with Wall-Adapting Local Eddy-Viscosity (WALE) sub-grid scale model in ANSYS-FLUENT were performed to capture the morphology of the breakup as well as the important flow field characteristics. A volume of fluid (VOF) approach was used to track the unsteady evolution and breakup of the liquid jet. Different results have been analyzed to assess this impact. These results are instantaneous and time-averaged axial velocity, liquid volume fraction, and turbulent kinetic energy. The results are represented in contours and centerline-and radial-profiles. The surrounding gas density is 34.5 kg/m 3 . The nozzle exit diameter is 0.05 mm. Three jet exit-velocities of 50 m/s, 100 m/s and 150 m/s are considered. The results showed that the predicted location, where drops and ligaments are first seen, moves away from the nozzle as the jet velocity increases, where this location was computed as 𝑥 = 3.5𝐷, 6.5𝐷 and 7.5𝐷 for Case50, Case100 and Case150, respectively. Also, the predicted location, where surface waves developed from Kelvin-Helmholtz instability are first seen, moves towards the nozzle as the jet velocity increases, where this location was computed as 𝑥 = 1.6𝐷, 1𝐷 𝑎𝑛𝑑 0.5𝐷 for Case50, Case100 and Case150, respectively. Regarding the jet dispersion angle and the liquid core length, it was found that they increase with increasing the jet exit velocity.