Time-resolved flow field investigation in an industrial centrifugal compressor application involving TR-PIV synchronized with unsteady pressure measurements

We report on combined velocity and unsteady pressure measurements obtained an radial compressor with vaneless diffuser asymmetric volute. Time-resolved PIV recordings were acquired at 26 kHz both upstream of the impeller as well within diffusor several rotation speeds clean conditions prior to onset instabilities rotor. The data was a high-repetition rate, double-pulse laser system consisting two DPSS lasers high-speed CMOS camera that synchronized multi-point measurements. Details facility, utilized instrumentation processing are provided particular focus spectral coherence analysis. Power spectra from time records inlet reveal increase low-frequency fluctuations below blade passing frequency occurrence mode-locked behaviour indicating presence rotating instabilities. High levels correlation between signals not only confirm temporal but also direct coupling flow field signature is more prominent rotor rather than in diffusor.