Big Blue Wind Tunnel
The “Big Blue” large recirculating wind tunnel is an experimental facility specially equipped to perform experiments on scaled-up geometries for high spatial resolution. Flow conditioning provides tight control of temperature and turbulence intensity level, and two bypass loops provide the capability of performing film cooling experiments. Removable glass-walled test sections allow optical access for laser-based velocity measurements and infrared surface temperature measurements, and there are provisions for multi-hole pressure probes. These capabilities have been used to perform detailed velocity, pressure, and surface heat transfer measurements on gas turbine airfoil cascades at engine relevant Reynolds number for up to 10X engine scale.
Schematic of Big-Blue facility
High-Density-Ratio (HDR) Film-Cooling Rig
In the High Density Ratio (HDR) wind tunnel, surface heat transfer experiments are performed to evaluate film-cooling designs at up to 20X engine scale. Liquid nitrogen is used to reduce the temperature (increase the density) of the coolant air while electric heaters are used to raise the temperature (lower the density) of the mainstream air to get a density ratio similar to that in gas turbine engines. The facility has optical access from three sides for laser-based measurements of the fluid flow and infrared thermography measurements of the film cooling surface.
Molly Eberly and Robert Schroeder measuring film cooling effectiveness in the HDR test facility.
High Speed Linear Cascade
The High Speed Linear Cascade is a steady-flow transonic facility that can operate at Mach and Reynolds numbers matched to engine conditions with true scale gas turbine airfoils. Capabilities include film cooling effectiveness measurements via infrared thermography, flowfield measurements with particle image velocimetry, and loss measurements with multi-hole pressure probes. The facility can match mainstream to coolant density ratios using a liquid nitrogen cooled cooling air system. The cascade has customizable guide walls and a turntable for a wide range of incidence angles. The airfoils can be easily inserted or removed from the side of the cascade for rapid testing turnaround and easy instrumentation access.
Exploded view of the cascade (top-right). Cascade piping system (bottom-left).