Abstract

In spite of advances in CFD prediction tools, the current design of outlet guide vane (OGV) stages for flow recovery downstream from low pressure turbines (LPT) still has to face significant flow entrance uncertainties. To ensure proper response of modern, high efficiency OGV’s, the sensitivity in the aerodynamic response of the vanes to both different levels of inlet turbulence and off-design incidence must be analyzed. To that end, a systematic experimental investigation of a current design LPT OGV airfoil has been undertaken in a low-speed linear cascade. Wall pressure distributions as well as high-resolution total pressure drop and LDV measurements have been used to determine the flow response. The experimental facility includes different boundary suction strategies for proper control of flow periodicity and endwall effects at significant off-design incidences. In addition, different inlet grids to promote an entrance flow having controlled isotropic background turbulence are included. The experimental flow response of the OGV airfoil is presented for a wide range of Reynolds numbers and different values of the inlet flow incidence and turbulence properties. Both at design and off-design incidences, different flow regimes and performance degradation mechanisms are discussed. In addition, the effect of inlet turbulence at close to design incidence is discussed, with the experimental evidence suggesting that its effect can be described by defining a properly scaled Reynolds number. The ability of CFD simulations based on currently available RANS transition models to describe the flow in high efficiency turbine OGV airfoils is finally explored.

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