Half-scale transonic compressor rapid testing rig

High-speed compressor testing is costly due to mechanical complexity and hazardous due to the high energy involved. In the past this has limited the speed and amount of testing. In this paper a new rig architecture is presented that aims to test a scaled transonic compressor stage rapidly. It builds upon the low-speed rapid testing developments made at the Whittle Laboratory and has potential to accelerate technology development. The power input requirement is reduced by testing at half-scale and reduced Reynolds number while maintaining the Mach number. Further power saving and mechanical simplification is achieved by employing a turbo-expander architecture with no shaft -power input, only the aerodynamic losses in system must be overcome. The aerodynamic and mechanical design of the rig is presented. Safe operation and rapid access and rebuild times are critical. The test hardware is machined from solid and bladed disks and rings can be manufactured in days. Only standard instrumentation is required, although a novel control loop is employed to achieve the same accuracy in rotational speed as an electric motor driven compressor rig. Experiments up to 25% design rotational speed were conducted, and the results presented here show that the rig is controllable and inherently safe if the research compressor fails. The rig will be run to full speed in the immediate future and extension to the capability is planned with multi -stage high-speed testing in a second machine.