Integrated Experimental and Numerical Approach for Fuel-Air Mixing Prediction in a Heavy-Duty Gas Turbine LP Burner

An integrated experimental-numerical procedure has been developed for fuel-air mixing prediction in a heavy-duty gas turbine burner. Optical measurements of the degree of mixing have been performed in a full-scale test rig operating with cold flow. Experimental data have been utilized to validate a CFD RANS numerical model. In fact, it is recognized that the turbulence behavior of jets in swirling air-flow stream is not accurately described by standard $k-ε$ turbulence models; therefore advanced turbulence models have been assessed by means of experimental data. The degree of mixing between simulated fuel and air streams has been evaluated at the burner exit section by means of a planar Mie scattering technique. The experimental apparatus consists of a pulsed Nd:YAG laser and a high resolution CCD video camera connected to a frame grabber. The acquired instantaneous images have been processed through specific procedures that also take into account the laser beam spatial nonuniformity. A second-order discretization scheme with a RSM turbulence model gives the best accordance with the experimental data. Such CFD model will be part of a more general method addressed to numerical prediction of turbulent combustion flames in LP technology.