THE STOCHASTIC STRUCTURE OF DOWNSTREAM PRESSURE FROM AN AXIAL COMPRESSOR .2. AN INVESTIGATION OF BLADE-TO-BLADE VARIABILITY

This work investigates the use of statistical and time-frequency analy sis of the downstream pressure signature to characterise blade-to-blad e variability of both average and residual pressure associated with a single row 36 blade axial compressor. Analysis of the average pressure signatures suggests that the blade mean pressure signatures are not i dentical at a 90% significance level. Analysis of the residual signatu res, obtained by removing the average signatures, reveals that the wak e region contains approximately four times as much power as the core f low region. Time-frequency analysis shows that the strong harmonic con tent which persists in the residual process is temporally concentrated in the wake flow region, but that the blade-to-blade variability of t his narrowband structure is sufficient to be almost eliminated upon av eraging of individual blade spectra. (C) 1996 Academic Press Limited