Swirling gas flow is an important topic of research that helps in the design of rockets, atomizers,and gas turbine combustors. In the present work, swirl flow inside annular geometries with constant and varying cross-sectional areas are examined using computational fluid dynamics (CFD). Effects of changing the flow and geometric parameters on the swirl behaviour were studied. Reynolds number was found to increase the swirl number in straight and diverging cross-sectional geometries while no significant effect of Reynolds number was observed in converging cross-sectional geometry. Radius ratio, defined as the ratio of the inner to the outer radius of the annular geometry, was found to have a significant effect on the swirl number. Decreasing the radius ratio, in straight and diverging annular geometry decreases the swirl number, however, an opposite trend was observed in the case of converging annular geometry due to significant increase in axial velocity as a result of reduced cross-sectional area. Increasing the swirler vane angle increased the swirl number. At higher vane angles of 60° and 70°, a recirculation zone is developed near the exit of the swirler. Using small cone angles was found to lower the swirl decay rate in converging and diverging nozzles.

涡流气流是一个重要的研究课题，有助于火箭、雾化器和燃气轮机燃烧器的设计。在目前的工作中，使用计算流体动力学 (CFD) 检查具有恒定和变化横截面积的环形几何形状内的涡流。研究了改变流动和几何参数对涡流行为的影响。发现雷诺数增加了直线和发散横截面几何形状中的涡流数，而在会聚横截面几何形状中没有观察到雷诺数的显着影响。半径比，定义为环形几何形状的内半径与外半径之比，被发现对涡流数有显着影响。减小半径比，在直的和发散的环形几何形状中会减少涡流数，但是，由于横截面积减小导致轴向速度显着增加，在会聚环形几何形状的情况下观察到相反的趋势。增加旋流器叶片角度会增加旋流数。在 60° 和 70° 的较高叶片角度下，在旋流器出口附近形成一个再循环区。发现使用小锥角可以降低会聚和发散喷嘴中的涡流衰减率。