FLOvane: A New Approach for High-Pressure Vane Design

This paper presents a new unconventional philosophy for high-pressure (HP) vane design. It is proposed that the most natural design starting point for admitting and accelerating flow with minimum loss and secondary flow is a trumpet-shaped flow-path which gradually turns to the desired angle. Multiple trumpet-shaped inlets are seamlessly blended into the (annular or partitioned) combustor walls resulting in a highly lofted flow-path, rather than a traditional flow-path defined by distinct airfoil and endwall surfaces. We call this trumped-shaped inlet the fully lofted oval vane (FLOvane). The purpose of this paper is to describe the FLOvane concept and to present back-to-back CFD analyses of two current industrial gas turbines with conventional and FLOvane-modified designs. The resulting designs diverge significantly from conventional designs in terms of both process and final geometric form. Computational fluid dynamic predictions for the FLOvane-modified designs show improved aerodynamic performance characteristics, reduced heat load, improved cooling performance, improved thermal–mechanical life, and improved stage/engine efficiency. The mechanisms for improved performance include reduction of secondary flows, reduced mixing of coolant flow with the mainstream flow, reduced skin friction, and improved coolant distribution. In the two current industrial gas turbine engines, the absolute (percentage point) improvement in stage isentropic efficiency when the FLOvane design was included was estimated at 0.33% points and 0.40% points without cooling flow reduction, and 1.5% points in one case and much more is expected for the other case when cooling flow reductions were accounted for.