An Experimental Investigation of Varied IGV Stagger Angle Effects on a High-Pressure Compressor
Creators: name: Beach, Amanda
Publisher: name: Purdue University Graduate School
Year: 2023
Subjects: Aerospace engineering not elsewhere classified

description: The focus of this work was to characterize the overall performance effects due to altering the stagger angle of a variable inlet guide vane (VIGV) on a multistage axial compressor. Data were collected from the Purdue three-stage axial compressor (P3S). The stagger angle from the VIGV was varied thrice from the baseline configuration in increments of 5 degrees resulting in four configurations with angles of 4 deg, 9 deg, 14 deg, and 19, where the baseline configuration was 9 degrees. Compressor performance data were collected and analyzed for each stagger angle configuration along three corrected speeds (68%, 80%, 100%). Each speedline consisted of approximately six loading conditions for which the corrected mass flow rate was matched for each configuration to allow for a basis of comparison among the configurations. Stalling mass flow rates and stall inception were also investigated. Total pressure and total temperature rakes were installed throughout the compressor to investigate the performance at interstage locations for each loading condition. In addition to the rakes, static pressure taps were distributed along the compressor and unsteady pressure measurements were distributed circumferentially. Capacitance probes were installed over each of the three rotors to evaluate rotor tip clearance measurements during the tests. The effects of the stagger angle on the stability margin of the compressor were also characterized. Each speedline presented, thus, includes a representative stall point in addition to the six loading conditions where detailed flow field traverses were conducted. The results of this investigation showed that while the total pressure ratio (TPR) increased as the stagger angle decreased, the stability margin was reduced. The opposite trend was observed with a decrease in overall TPR across the compressor and an increase in stability margin for increased stagger angles. Based on findings from previous authors, this trend was anticipated. A similar metric for monitoring compressor performance is isentropic efficiency. This investigation utilized both temperature-based and torque-based isentropic efficiency. The greatest effect of the VIGV stagger angle on compressor isentropic efficiency occurred at the lowest loading conditions, and there was no discernible impact on isentropic efficiency at high loading conditions for this case. As VIGVs typically have the greatest impact on off-design conditions, this trend was expected. The varied stagger angle configurations had no discernible effect on the type of stall inception mechanism experienced by the compressor. The primary effect on stall that was consistent across the configurations was a noticeable increase in the duration and strength of modal oscillations present throughout the compressor with increased stagger angles, indicating an increase in stability. The data collected and presented herein provide a unique, robust dataset to improve understanding of the effects of changing stagger angles on variable inlet guide vanes on multistage axial compressors. These data correspondingly provide a unique training set and validation method for predictive technology.