INSTANTANEOUS 3-DIMENSIONAL FLOW VISUALIZATION BY RAPID ACQUISITION OF MULTIPLE PLANAR FLOW IMAGES

A flow visualization system is described that provides 3-D snapshots o f instantaneous flow structures by rapidly acquiring successive image planes from within the flow. For each 3-D snapshot, up to 20 planar im ages are collected at the rate of 10,000,000 images/s. Flow visualizat ion at successive planes is by planar particulate scattering or planar laser-induced fluorescence using a laser sheet rapidly swept once acr oss the flow by a 30,000-rpm polygon scanner, Variations in the laser sheet intensity are monitored by placing an on-edge image of the sheet on the periphery of every planar flow image. The camera is a high-spe ed image converter coupled by fiber optics to a slow-scan CCD camera. The fiber optics provide 2.5 times better light gathering efficiency t han lens coupling without reducing the available spatial resolution. T he overall measurement technique shows excellent potential as demonstr ated with a selection of 3-D measurements.