Application of DPIV to study both steady state and transient turbomachinery flows

Digital particle imaging velocimetry (DPIV) is a powerful measurement technique, which can be used as an alternative or complementary approach to laser doppler velocimetry (LDV) in a wide range of research applications. Thr instantaneous planar velocity measurements obtained with PIV make it an attractive technique for use in the study of the complex Row fields encountered in turbomachinery, The planar nature of the technique also significantly reduces the facility run time over point-based techniques. Techniques for optical access, light sheet delivery, CCD camera technology and particulate seeding are discussed. Results from the successful application of the PIV technique to both the blade passage region of a transonic axial compressor and the diffuser region of a high speed centrifugal compressor are presented. Both instantaneous and time-averaged Row fields were obtained. The averaged Row held measurements are used to estimate the Row turbulence intensity. The instantaneous velocity vector maps obtained during compressor surge provide previously unobtainable insight into the complex Row field characteristics occurring during short lived surge events. These Row field maps illustrate the true power of the DPIV technique. (C) 2001 Elsevier Science Ltd. All rights reserved.