AUTOMATIC PARTICLE-IMAGE VELOCIMETRY UTILISING LASER-INDUCED FLUORESCENT PARTICLES

Microscopic, neutrally buoyant particles containing fluorescing compound have been adapted as tracers for velocity measurements of large scale turbulent flows. This technique consists of illuminating a thin slice of the flow field with a laser sheet, which is pulsed following a specific illumination code. The multiple exposure image is recorded on photographic film and later enhanced while being digitised. Algorithms have been developed for analysing the resulting images. They rely on the illumination code and the particle streak morphology in order to identify and compute the tracer velocity vectors. A one-inch diameter jet has been used as a flow field for preliminary tests.