High resolution multigrid cross-correlation digital PIV measurements of a turbulent starting jet using half frame image shift film recording

This paper describes a novel approach of acquiring two single-exposed, non- overlapping images using half frame image shift (HFIS) recording on photogr aphic film. This technique permits the recording of two single-exposed, non -overlapping images of seed particles in a flow plane on high spatial resol ution film with any arbitrary time delay between exposures. A new multigrid CCDPIV (MCCDPIV) analysis method is used to analyse the single-exposed, no n-overlapping sequential images resulting in PIV measurements with a larger velocity dynamic range, lower random error and better spatial resolution t han standard CCDPIV analysis. HFIS recording followed by MCCDPIV analysis w as employed to measure the spatio-temporal evolution of the in-plane veloci ty vector and the out-of-plane vorticity fields of a turbulent starling jet at Reynolds numbers based on the orifice diameter and piston velocity of 1 0,780 and 13,860. (C) 1999 Elsevier Science Ltd. All rights reserved.