Urans and Les Cfd Simulations of Swirl Stabilized Non-Premixed Tecflam Combustor

Abstract

Simulating a gas turbine combustor is a challenging issue due to complexity of both flow and reaction kinetics. URANS, Unsteady RANS, is an interesting approach for simulating transient reacting flows in combustors. Studies clearly indicate the superiority of LES, Large Eddy Simulation, over URANS computations. However, it is also well known that URANS computations have surely CPU overhead advantages over the more CPU costly LES approaches. In this study, URANS computations are carried out on a highly swirled non-premixed combustion chamber by applying four mesh densities from 0.3M to 11.5M block-structured hexahedral cells. TECFLAM S09 methane-air case with 0.9 swirl number is investigated due to its similarity to stationary gas turbine combustors. Simulations showed that URANS is unable to capture the complexity of swirling effects as good as LES predictions even on a computational mesh with 2.7M elements. The strong inner recirculation zone is predicted with a good degree of accuracy with LES computations while it cannot be captured by URANS approach. © 2015 Begell House, Inc.