An Investigation of RANS Simulations for Swirl-Stabilized Isothermal Turbulent Flow in a Gas Turbine Burner

Abstract

The presence of complex flow features in swirling flows have made it an essential part of many engineering applications. These features can only be accurately predicted by the DNS or LES type methods which are highly expensive in terms of resources and time. This fact established the RANS approach as the key method in the industrial arena because of its modest requirement of resources unlike LES. However, existing RANS investigations on swirl-stabilized isothermal turbulent flow are 2D and lack credibility on the question of predicting the prominent flow features which exist in swirling flows. The current study investigates the 3D RANS simulations in predicting a swirl-stabilized isothermal turbulent flow in a burner for a gas-turbine combustion chamber which possesses complex flow features such as bluff-body induced recirculation zone and Vortex Breakdown (VB) bubble. Current investigations also assess the establishment of 3D RANS simulations as a viable industrial alternative to the computationally expensive LES and the less accurate 2D RANS simulations. Furthermore, the influence of mesh quality, different turbulence models, discretization schemes on the accuracy of the predictions are examined. It was found that the multi-zonal mesh with hexahedron cells had the highest mesh quality and produced the best results, and the standard ????- ???? model predicted all the flow features with default schemes in ANSYS-Fluent. The conclusions in the paper are valuable, practical and will save a lot of time and effort of practicing engineers during the numerical modelling setup selection stages for solving such complex three-dimensional flow problems.