ANALYTICAL AND EXPERIMENTAL INVESTIGATIONS OF DUAL-PLANE PARTICLE IMAGE VELOCIMETRY

In its classical form particle image velocimetry (PIV) extracts two co mponents of the flow velocity vector by measuring the displacement of tracer particles within a double-pulsed laser light sheet. The method described in this paper is based on the additional recording of a thir d exposure of the tracer particles in a parallel light sheet, which is slightly displaced with respect to the first one, The particle images resulting from these three exposures are stored on separate frames. T he locations of the correlation peaks, as obtained by cross-correlatio n methods, are used to determine the projections of the velocity vecto rs onto the plane between the two light sheets, The amplitudes of thes e peaks are used to obtain information about the velocity component pe rpendicular to the light-sheet planes, The mathematical background of this method is described. Numerical simulations show the influence of the main parameters (e.g., light-sheet thickness, light-sheet displace ment and out-of-plane flow component) on the resolution and reliabilit y of the new method. A new recording procedure and its results will be shown to demonstrate the ease of operation when applying this techniq ue to liquid flows. (C) 1996 Society of Photo-Optical Instrumentation Engineers.