Effect of preheated swirling multi-annular jets on mixing and flow characteristics in various expanded confinements

Abstract Understanding how preheated multi-annular swirling air jets mix within confinements of different expansion ratios is crucial. This knowledge is essential for applications like gas turbine combustors, where efficient mixing and maintaining flame stability are essential for optimal performance. The central recirculation zone (CRZ) is crucial in improving mixing in swirling confined flows. This investigation focuses on the computational analysis of the mixing and flow characteristics of three swirling air jets, considering the effects of varying expansion ratios and preheating of the jets within different confinements. The study utilized the CFD software ANSYS FLUENT to investigate the impact of jet preheating on the recirculation zone and flow behavior within confinement. The Realizable k-ε turbulence model was employed, and the CFD code was validated by comparing its results with experimental data available in the literature. In the present investigation, it was found that the preheating of jets influences the size of the recirculation zone at a specific swirl combination. The findings offer valuable insights into the mixing behavior of preheated jets in both non-expanded and expanded confinements.