Experimental and Computational Characterization of Flow Rates in a Multiple-Passage Gas Turbine Combustor Swirler

One of the challenges of gas turbine combustor research is to accurately measure and model air mass flow rates through complex air injection schemes. Accurate measurements and computations of air mass flow rates are necessary for determining air and fuel distributions, which influence a range of combustor operation and performance characteristics. Experimental and computational studies were performed on a representative gas turbine combustor swirler. The swirler geometry consists of four component flows: two co-rotating annular axial swirls, one radial swirl, and cooling on the periphery of the swirler. The purpose of this study is to compare measured and computed air mass flow rates in a realistic swirler with a complex geometry and to quantify the magnitude of the interaction effects between air passages. The measurements of the air mass flow rates were performed using a calibrated air flow stand. The computations were performed using commercial Computational Fluid Dynamics (CFD) tools. Comparisons between measured and computed air mass flow rates show good agreement for the individual and total flow configurations. Significant interaction effects among the swirling flows are observed when all of the air passages are open. The radial swirl mass flow rate decreases by 2.7% and the outer axial swirl mass flow rate increases by 3.8% when the individual component flow configuration is compared to the total flow configuration. The computed mass flow rates demonstrate that the interactions among the swirl flows create a significant change in mass flow distribution within the swirler.