Phantom Cooling Effects on Rotor Blade Surface Heat Flux in a Transonic Full Scale 1 + 1/2 Stage Rotating Turbine

Abstract

An experimental and numerical investigation of phantom cooling effects on cooled and uncooled rotating high pressure turbine blades in a full scale 1 + 1/2 stage turbine test is presented. Objectives set to capture, separate, and quantify the effects of upstream vane film-cooling and leakage flows on downstream rotor blade surface heat flux. Multiple series of 1 + 1/2 stage rotating high pressure turbine tests were carried out in the Air Force Research Laboratory, Turbine Research Facility, at Wright-Patterson Air Force Base, Ohio. A non-proprietary research turbine was instrumented with high frequency double-sided thin film heat flux gauges custom made at AFRL. High bandwidth, time-resolved surface heat flux is measured on multiple film-cooled and non-film-cooled HPT rotor blades downstream of both film-cooled and non-film-cooled vane sectors. Upstream wake passing and heat flux is characterized on both rotor pressure and suction side surfaces, along with quantifying rotor phantom cooling effects from non-uniform first-stage vane film cooling and leakage flows. Fast response heat flux measurements quantify how rotor phantom cooling impacts the blade pressure side greatest. Measurements show upstream vane film-cooling alone can account for 50% of the rotor blade cooling effect in some instances, and even outweigh the rotor blade film cooling effect far from the blade showerhead holes. Added unsteady aero numerical simulation demonstrates how variations in inlet total temperature and incidence angle also contribute to the circumferentially non-uniform rotor heat flux. Results from this investigation aid modeling and design efforts in optimizing film cooling performance in real high-pressure turbine flow fields. Understanding the behavior of such non-uniform circumferential rotor phantom cooling effects can be critical to optimizing the efficiency, fuel consumption, range, and durability of advanced turbomachines.