An experimental study of the turbulent transverse jet

An experimental study that examines the mean flow properties of the turbulent transverse jet using Digital Particle Image Velocimetry (DPIV) is reported. This study examines various jet flows over a range of Reynolds numbers based upon jet velocity and diameter. Within this range it is documented that mean flow fields, identified as alternate mean flow states, other than the symmetric vortex pair exist. These alternate flow states are characterized by unsteadiness, asymmetry, and multiple streamwise vortices. Flow visualization shows that these alternate flow states are formed during initial jet roll-up, and persist far downstream without developing into the (expected) vortex pair. A map of the domain of existence, in velocity ratio - Reynolds number space, of these alternate states is provided, and a discussion of the underlying physics is included. With this new understanding, selected symmetric jet flows at velocity ratios of 5, 10, and 20 are generated and studied using DPIV. The mean flow is quantified through measurements of vortex circulation, size, and impulse, and the relationship of these properties to the (initial) jet momentum flux is examined.