78 Augmentation of Turbulence and Mixing in Gas Turbine Combustors by Introducing Unsteady Effects

Turbulence production and mixing are crucial for flame stability in gas turbine combustors. Designers have relied on fixed geometry swirlers to introduce a tangential component to the inlet air flow in order to sustain a central recirculation zone able to enhance the mixing process and stabilize the flame. In this paper we propose a novel swirler for gas turbine combustors. The new swirler concept is composed of a conventional vane swirler and a rotating element which interrupts the swirling flow. Such unsteady interruption enhances the turbulence and mixing characteristics of the swirling flow. The novel concept is assessed by performing four numerical simulations at four different angular velocities for the rotating element which are 0, 240, 480, and 960 rpm. A trend of increasing turbulence kinetic energy with the rotating element angular velocity was observed.