Near-Stall Modal Disturbances Within a Transonic Compressor Rotor
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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This research effort seeks to better understand non-periodic flow characteristics for a forward swept axial transonic compressor rotor when operating near stall. Improved performance of a military gas turbine engine may be achieved by better understanding the mechanisms responsible for near-stall non-periodic disturbances within a transonic compressor rotor. Using pressure transducers, embedded within the rotor wall casing, data were acquired and calibrated at various speeds up to 90 of maximum rotation velocity. Within the 90 design speed, various data sets were acquired for different throttle configurations. A new method to post-process the data to allow better investigating of the non-periodic flow characteristics was developed. Using Fast Fourier Transforms, two distinct and dominant frequencies were identified and analyzed. Contour pressure distribution maps for varying throttle configurations and the amplitude differences for each frequency of interest was generated to illustrate correlations in frequency strength and its relationship with tip-leakage vortices, normaloblique shocks, and passage-to-passage interactions. This study uses effective instrumentation and robust data reduction techniques to successfully identify passage-to-passage distribution of non-periodic and periodic low dominant frequencies within the rotor blade passage prior to stall.
- Hydraulic and Pneumatic Equipment