Time resolved 3D passive scalar concentration-field imaging by laser induced fluorescence (LIF) in moving liquids

This paper discusses the experimental setup of a 3D LIF imaging facility. The advected scalar concentration field of a LIF dye is digitized quasi-instantaneously. The x- and y-resolution are determined by the camera optic, the z-resolution by the scan process. In the absence of scan noise, spatial resolution can be designed to be equal in all three directions, The thus obtained 3D field can be used as input signal for an optical flow measurement technique. The scope of the imaging is mainly constrained by the local Reynolds number of the flow and the state of current high-speed digital cameras and laser scanners. The reciprocal relationship of the important parameters is discussed along with some implementational examples for the turbulent free jet.