Velocity visualization in gas flows using laser-induced phosphorescence of biacetyl

Visualization of a two-dimensional velocity field by means of laser-induced phosphorescence is demonstrated in a nitrogen flow at room temperature. A pulsed dye laser is used to excite seeded biacetyl molecules along a line in the flow. Two successive exposures of the emitted phosphorescence are recorded with an intensified 100×100 element photodiode array camera. Velocities are determined from the distance traveled in the time interval between exposures. Important factors in connection with the phosphorescence of biacetyl are discussed.