Abstract
The present investigation was carried out to obtain a better understanding of the turbulent structure in a slit nozzle air jet. A series of measurements were made simultaneously by using arrays of hot-wire anemometers with x-probes. The signals were digitized and recorded on magnetic tape. Based on the data, instantaneous velocity vector fields seen from a frame moving at a constant velocity were drawn. They confirm the existence of a row of large-scale eddies whose rotation directions are the same and also show that the interaction of these eddies beyond the jet centerline forms a configuration of quasiperiodic counter-rotating eddies approximately alternating on opposite sides of the centerline in both the transitional and the fully developed turbulent regions of a slit nozzle jet.
Inward large-scale flow, whose longitudinal u′ and lateral v′ fluctuating velocities are both negative, and outward large-scale flows, whose u′ and v′ are both positive, appear frequently in a slit nozzle jet. The former and the latter respectively correspond to the “ejection” and the “sweep” in a turbulent boundary layer.
