Experimental and Numerical Studies of the Velocity Field of a Triple Annular Swirler

Abstract

Modern industrial gas-turbine spray combustors feature multiple swirlers and distributed fuel injection for rapid mixing and stabilization. The present paper is the first of a sequence of papers that aim to study the flow field of such combustors, the related combustion characteristics and their control. The present paper focuses on an experimental investigation of the velocity flow field downstream of a Triple Annular Swirler (TAS) and CFD description of the flow field inside the TAS. Multiple combinations of swirlers of various swirl level and rotational direction were tested in cold flow under atmospheric conditions without a confining combustion chamber. The experiments showed that a Central Toroidal Recirculation Zone (CTRZ) and an annular jet with internal and external shear layers characterize the flow field downstream of TAS. The CTRZ is axisymmetric but the jet contains imprints of the internal flow and has some nonaxisymmetric features. Numerical RANS results confirmed these observations and showed that the asymmetry relates to the effect of the internal swirling vanes on the jet flow.