Mm. Bright et al., Investigation of pre-stall mode and pip inception in high-speed compressors through the use of correlation integral, J TURBOMACH, 121(4), 1999, pp. 743-750
Citations number
22
Categorie Soggetti
Mechanical Engineering
Journal title
JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME
Five high-speed compressor configurations are used to identify, pre-stall p
ressure signal activity under clean and distorted inlet conditions, and und
er steady injection and controlled injection conditions. Through the use of
a nonlinear statistic called correlation integral, variations in the compr
essor dynamics are identified fr om the pre-stall pressure activity far bef
ore variations (,nodal or pip) are observed visually in the wall static pre
ssure measurements. The correlation integral not only discerns changing dyn
amics of these compressors prior to stall, but is now? used to measure the
strength of the tip flow field for these five high-speed compressors. Resul
ts show that correlation integral value changes dramatically when the stall
inception is modal; and it changes less severely when the stall inception
is through pip disturbances. This algorithm call therefore distinguish from
the pre-stall pressure traces when a machine is more likely to stall due t
o pips versus modes. When used irt this manner, the correlation integral th
us provides a measure of tip flow strength. The algorithm requires no predi
sposition about the expected behavior of the data in order to detect changi
ng dynamics in the compressor; thus, no pre-filtering is necessary. However
, by band-pass filtering the data, one can monitor changing dynamics in the
tip flow field for various frequency regimes. An outcome of this is to ass
ociate changes in correlation integral value directly with frequency specif
ic events occurring in the compressor, i.e., blade length scale events vers
us long length scale acoustic events. The correlation integral provides a p
otential advantage over linear spectral techniques because a single sensor
is used for detection and analysis of the instabilities.