Wind Tunnel Testing and Modeling Implications of an Advanced Turbine Cascade

Abstract

This paper describes the extensive Wind Tunnel (WT) linear cascade testing campaign carried out on a constant section turbine blade developed for low subsonic applications. Comprehensive experimental program was designed to determine the aerodynamic behaviour of this blade under a wide range of varying geometrical like Pitch to Chord Ratio, Stagger Angle and Aerodynamic like Reynolds Roughness, Mach number, Incidence angle conditions. In addition to the classical Two-Dimensional (2D) measurements, targeted Three-Dimensional (3D) surveys have been performed to complement the 2D results, allowing to draw supplementary conclusions as to the behaviour of the considered blade in three-dimensions. The performed experiments predominantly covered the transitional and beginning of a fully turbulent flow regime (maximum Re is 2.5 million). Post processing of experimental results were done in view of exploitation and judgment of some key aerodynamic aspects; parameters such as profile section load distribution, loss coefficient and flow deviation angle. Alongside with confirmation of the design targets, a parallel goal pursued in the current WT testing, was to get a more accurate idea as to the predictive capabilities of the employed CFD tools (CFX and MISES) under the basic flow condition generated in the WT. The aim was to get a global picture, as to the level of agreement that can be reached by the used design tools while accounting for the afore-mentioned design, operational variables. The obtained measurement results clearly indicated the success of the design in achieving the pre-set targets. The paper further provides a detailed discussion on the identified discrepancies, measurement versus predictions, of the key parameters at the geometric, aerodynamic design as well as off-design conditions.