Characteristics of a turbulent plane offset jet

A plane, incompressible, turbulent air jet is discharged into quiescent ambient surroundings above a plate offset from, and parallel to, the axis of the jet discharge. Entrainment of the fluid below the jet and above the plate causes a reduced pressure in this region forcing the jet to deflect towards the boundary and eventually attach to it. Velocity data for the primary jet flow and the recirculation region were obtained and the attachment length was determined. Mean veocity data within the recirculation region is used to determine a dividing streamline which, on average, separates the primary jet flow from the recirculation region. The primary jet flow entrainment was found to have wide variations in the region prior to the jet attachment, and is seen to be related to the distribution of pressure in the recirculation region. Results show the local jet entrainment parameter to be significantly different from that of either a free jet or wall jet. The effective drag of the recirculation region on the primary jet flow was determined as well as distributions of higher order moments, energy spectra, autocorrelation functions, and integral scales. Turbulence energy spectra show that the relative energy content shifts from higher to lower frequencies and the rate of energy decay in the low frequency range increases as the jet approaches impingement.