Experimental and numerical investigation of isothermal flow in an idealized swirl combustor

Purpose - The main purpose of the paper is the validation of different modelling strategies for turbulent swirling flow of an incompressible fluid in an idealized swirl combustor. Design/methodology/approach - Experiments have been performed and computations carried out for a water test rig, for a Reynolds number of 4,600 based on combustor inlet mean axial velocity and diameter. Two cases have been investigated, one low swirl and the other high swirl intensity. Measurements of time-averaged velocity components and corresponding rms turbulence intensities were measured using laser Doppler anemometer, along radial traverses at different axial locations. In the three-dimensional, unsteady computations, large eddy simulation (LES) and URANS (Unsteady Reynolds Averaged Navier-Stokes Equations or Reynolds Averaged Numerical Simulations) RSMs (Reynolds-stress models) are basically employed as modelling strategies for turbulence. To model subgrid-scale turbulence for LES, the models due to Smagorinsky and Voke are used. No-model LES and coarse-grid direct numerical simulation computations are also performed for one of the cases. Findings - The predictions are compared with the measurements and reveal that LES provided the best overall accuracy for all of the cases, whereas no significant difference between the Smagorinsky and Voke models are observed for the time-averaged velocity components. Originality/value - This paper provides additional valuable information on the performance of various modelling strategies for turbulent swirling flows.