The Purdue High-Speed Small Core Turbine Facility

Short-duration facilities, with testing time on the order of milliseconds to seconds, offer cost-effective solutions to achieve engine-relevant pressure and temperature ratios. Short-duration facilities have high levels of heat loss that require careful accounting for efficiency calculation[1]. The Purdue Small Turbine Aerothermal Rotating Rig (STARR) was developed to test engine-representative hardware for small core turbine applications. The STARR facility is a two-stage rotating test turbine running at engine-representative Reynolds and Mach numbers capable of fast transients and steady operation for up to 6 hours with the enhanced pressure vessels in development. The facility is purpose-built to test advancements in critical technologies for clean aviation, pushing towards higher OPR engines, hybrid propulsion, and multi-stream engines. The facility is designed to be modular, allowing faster turnaround times for new test articles. This paper presents the design, control, and operation of the facility. Efficiency measurements in engine-representative test rigs are a challenging prospect due to the narrow uncertainty band required, ideally less than 0.5% uncertainty, to detect the incremental improvements achieved by turbine designers. For a small core turbine, accurately quantifying the tip clearance is also critical to assess relative changes in performance. To that end, the instrumentation used for efficiency measurement and resolving unsteady flow phenomenon is presented. The inlet characterization and commissioning of the test section are presented. Uncertainty is quantified on efficiency measurement through a comprehensive framework [2] that includes both precision and absolute level of uncertainty. The uncertainty is propagated from the individual sensor to the final efficiency calculation. The total uncertainty for mechanical efficiency presented is of the order of 0.55%. The challenges faced in the operation of such a facility are highlighted, along with the steps proposed to mitigate them.