Effect of various angular outlets on mixing of swirling multi-annular jets in different expanded confinement

Multi-annular jets are derived from coaxial jets, which are used to improve the mixing of fuel and air before ignition in a gas turbine combustor and it is essential to achieving stable and effective combustion. In the present work, a multi-annular jet comprising two co-annular and one central jet has been used to understand the flow characteristics and mixing of jets in non-expanded and expanded confinement with different angular outlets. A computational investigation has been performed with different swirl combinations in three air jets inlet under non-combustion conditions. After validation from existing experimental results, parametric studies have been investigated with different expansion ratios, different swirl combinations, and different angular outlets. Using the realizable k–ε turbulence model and commercial software ANSYS FLUENT, results were obtained in the form of streamlines plots, axial velocity contours, and center line axial velocity. Following a comprehensive analysis of the computational output, it is found the mixing process in confinement depends on expansion ratios, swirl combinations, and angular outlets. Results show that the mixing of jets is enhanced in expanded confinement at particular swirl combinations and at certain angular outlets.