Impact of Trailing Edge Damage on Nozzle Guide Vane Flow Capacity

Abstract In this paper, we consider the impact of trailing edge burn-back (due to oxidation damage) on the flow capacity of cooled transonic high-pressure (HP) nozzle guide vanes. The purpose is to provide understanding that can lead to improved whole-life engine performance modelling. We present experimental results from an ultra-low uncertainty experiment in a full-annulus nozzle guide vane cascade and compare these with results from high-fidelity computational fluid dynamics simulations. Experiments were performed in the engine component aerothermal (ECAT) facility at the University of Oxford, using a sequence of four geometries with increasing simulated burn-back. We find that for fixed vane pressure ratio, increased burn-back leads to: increased overall vane capacity, with changes from the nominal geometry of +2.7%, +7.4%, and +16.1%; increased coolant capacity, with changes from the nominal geometry of +2.4%, +6.9%, and +15.0%; and significant variation in whirl angle distribution within the burn-back region, with little effect on the outside region. There is very poor correlation between the change in geometric minimum area and the vane capacity change, highlighting the need to consider the aerodynamics in the entire controlling region of the vane. Taken together with a related paper on the impact of burn-back on aerodynamic performance, these papers provide a basis for an HP stage model within a whole-life engine performance model.