A cross correlation PIV technique using electro-optical image separation

A new approach for 2D flowfield investigation by particle-image velocimetry (PIV) has been developed for measurements with high spatial resolution without the well known directional ambiguity. This feature of the technique is especially important for measurements in flows with reversal regions or strong turbulent motion as in-cylinder engine measurements. The major aim of the work was to achieve the benefits of cross correlation PIV image evaluation at reasonable cost and under application of common single wavelength double-pulsed laser systems as they are mainly used for PIV experiments. The development of the technique is based on polarization rotation of the light scattered by the seeding particles by means of a ferroelectric liquid crystal half wave plate. Measurement samples from low turbulent jets and the flow in the wake of a cylinder are being presented. (Author)