Experimental and 3D CFD Investigation in a Gas Turbine Exhaust System

Both experimental and 3D CFD investigations are carried out in a scale model of an industrial gas turbine exhaust system to better understand its complex flow field and to validate CFD prediction capabilities for improved design applications. The model consists of an annular diffuser passage with struts, followed by turning vanes and a rectangular plenum with side exhaust. Precise measurements of total/static pressure and flow velocity distributions at the model inlet, strut outlet and model outlet are made using aerodynamic probes and locally a Laser Doppler Velocimeter (LDV). Numerical analyses of the model internal flow field are performed utilizing a three-dimensional Navier-Stokes (N-S) calculation method with the industry standard k-ε turbulence model. Both the experiments and computations are carried out for three load conditions: full speed no load (FSNL), full speed mid load (FSML, 57% load), and full speed full load (FSFL). Based on the overall comparison between the measurements and CFD predictions, this study concludes that the applied N-S method is capable of predicting complicated gas turbine exhaust system flows for design applications.