Compressor Performance Analysis Under Off-Design and Surge Conditions

Transient compressor system analysis and modeling is limited by a lack of surge performance data. This hinders the development of sophisticated model applications, such as model predictive control. To fully realize dynamic simulation capabilities, representative estimates of the compressor performance across the full operating range are needed. This work characterizes the performance of a single-stage centrifugal compressor operating under off-design and surge conditions, with a focus on the positive-slope area of the compressor map. Continuous performance curves are obtained from zero flow to max capacity for three inlet guide vane settings and two rotational speeds. Steady-state performance tests per ASME PTC 10 provide the normal parts of these curves. Polytropic head and efficiency during transient surge operation are estimated using the Schultz procedure, assuming quasi-steady behavior. Gas and shaft power values are calculated using thermodynamic relations and flow, torque, and speed measurements, enabling an assessment of the system energy balance. Challenges related to the test protocol are addressed, including temperature shifts and flow instabilities. The results provide valuable insights into compressor surge performance across a broad set of conditions, thereby contributing to an improved understanding of transient compressor instability behavior.