Investigators: Professor Tom Povey

Students: James Parker

Sponsors: Rolls-Royce Turbines

The Transonic Rotor Cooling facility at the University of Oxford is a new high-pressure linear cascade designed for low technology-readiness level research of rotor platform cooling. It will be used for aerothermal research into flow interactions between seal leakages across the platform, to develop and assess novel cooling systems, and computational fluid dynamics validation.

The test section contains five rotor blade passages formed by linearised versions of engine components and bounded by contoured endwalls. Test components are complete scaled-up blades, which include fir tree roots, housed in a modular cassette representative of engine disk and hub seal geometry. This novel arrangement allows for all seal leakage flows and their aerothermal impact on platform cooling to be assessed. The coolant supply to the front hub seal, shank pocket and blade, and rear seal can be varied independently. The flexibility of coolant supply, and modularity of the test section, allows for varied cooling systems to be implemented in the blade platforms. Limited geometric changes, such as the introduction of swirl fins, can also be made to the front and rear hub seals to, for example, model the effect of rotation-induced swirl on the cooling performance of leakage flows.

The facility operates at scaled engine conditions with matched Mach number, Reynolds number, coolant-to-mainstream pressure ratios, and inlet turbulence intensity. Overall cooling effectiveness measurements of two complete blade platforms can be obtained with a high level of precision via infrared thermography. Measurement techniques developed previously in the University of Oxford Sector facility will be employed so that thermal assessments can be made using laser sintered test components. This allows for a rapid turnaround of components and significantly reduces the time and costs of introducing and modifying platform cooling systems. Aerodynamic measurements are also possible to allow for aerodynamic performance effects of cooling to be examined.

Figure 1: 3D CAD representation of working section in the transonic rotor cooling facility.
Figure 2: 3D CAD of visible rotor platform area for IR metal effectiveness measurements and internal cooling feed representative of engine geometry.