Assessment of steady VOF RANS turbulence models in rendering the internal flow structure of pressure swirl nozzles

Abstract

This study deals with a series of two-phase flow, computational fluid dynamics (CFD) simulations, to assess the performance of the steady Reynolds averaged Navier–Stokes (RANS) scheme. The study utilizes a high-pressure swirl nozzle at inlet injection pressure of 15 bar. In this particular nozzle, the volume of the swirl chamber is adjustable to change the spray pattern from a hollow cone to full cone at its minimum and maximum volume, respectively. The spray angle of this nozzle was measured from 1,000 images captured experimentally via a high-speed camera. Commercial CFD code (STAR CCM+ version 11.04) was used to solve the Navier–Stokes equations implementing volume-of-fluid method to simulate the internal flow structure. An extensive description is provided regarding grid sensitivity analysis and essential correlations with experimental results are introduced. Two of the most popular RANS turbulence models, namely realizable k-ε (RK-ϵ) and k-ω shear stress transport (SST), are then used and their ability to render the complex internal flow field is compared. The grid dependency study shows that none of the two models are grid independent due to the unsteady behavior of the internal flow field. Both models are inaccurate for predicting the liquid film thickness, and when the k-ω SST is superior for predicting of the spray angle.