This paper details the development of a Single Stage Centrifugal Compressor (SSCC) research facility at Purdue University in collaboration with Honeywell. The research vehicle is a Honeywell experimental compressor that has been specifically outfitted with a variety of instrumentation for research purposes. Both steady-state and fast-response instrumentation will be used to provide benchmark experimental data for performance and aeromechanics tool development and validation. Some unique facility aspects include real-time clearance control, active bleed flow management, fast-response pressure sensors embedded in the impeller, and a full circumferential traverse at the compressor inlet to facilitate inlet distortion quantification. The details of the facility and baseline results are presented.

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A new method of modeling slip factor and work input for centrifugal compressor impellers is presented. Rather than using geometry to predict the behavior of the flow at the impeller exit, the new method leverages governing relationships to predict the work input delivered by the impeller with dimensionless design parameters. The approach incorporates both impeller geometry and flow conditions and, therefore, is inherently able to predict the slip factor both at design and off-design conditions. Five impeller cases are used to demonstrate the efficacy of the method, four of which are well documented in the open literature. Multiple implementations of the model are introduced to enable users to customize the model to specific applications. Significant improvement in the accuracy of the prediction of slip factor and work input is obtained at both design and off-design conditions relative to Wiesner's slip model. While Wiesner's model predicts the slip factor of 52% of the data within ±0.05 absolute error, the most accurate implementation of the new model predicts 99% of the data within the same error band. The effects of external losses on the model are considered, and the new model is fairly insensitive to the effects of external losses. Finally, detailed procedures to incorporate the new model into a meanline analysis tool are provided in the appendices.

The identification of stall inception mechanisms and stability-limiting components in a centrifugal compressor is required for development of effective surge suppression approaches. Part 1 of this two-part paper investigates the surge signature of a centrifugal compressor at subsonic, transonic, and supersonic inlet tip conditions, and Part 2 considers the relationship of the surge signature with the compressor static pressure characteristics as well as the impeller leading edge relative tip Mach number. Experiments were performed in the Single Stage Centrifugal Compressor (SSCC) facility at Purdue University with both steady performance and dynamic pressure data recorded. Results show the presence of both mild and deep surge on the compressor map. Deep surge occurs at subsonic and supersonic impeller tip relative Mach numbers while mild surge is observed as the tip relative Mach number nears unity. Long length-scale modal oscillations can be detected only at the transonic operating condition while spike disturbances are identified as the precursor to instability at subsonic and supersonic tip relative Mach numbers. Finally, the impeller is determined to be the origin of instability throughout most of the compressor map. The observation of impeller-induced instability refreshes the conventional understanding that the diffuser is typically the stability-limiting component for centrifugal compressors with vaned diffusers and suggests various surge suppression approaches may be necessary to achieve range extension throughout a compressor map.