Aerodynamics of a Fuel Spoke in a Gas Turbine Combustor

The three-dimensional unsteady flow in a gas turbine combustor was studied using CFD means. The flow structure around a fuel spoke is of interest not only because of pollutant issues, but also because of combustor operating issues such as combustion acoustics and potential flame-holding in the premixer. The CFD model was tested extensively in terms of grid density and lime-marching step size before the final calculation was made. It was shown that when a swirling flow crosses over a cylindrical fuel spoke, wake vortices are formed and a strong secondary flow is generated along the spanwise direction. A secondary vortex existed near the tip of the spoke. This complex flow structure affects the quality of fuel and air mixing and can be addressed by CFD-based design methods.