The structure of a self-preserving turbulent plane jet

Abstract

The structure of a self-preserving turbulent plane jet exhausting into a slow-moving parallel airstream is studied. The investigation includes results of turbulence measurements and the structure is compared with that of a self-preserving plane wake. The results show that self-preservation is established at a distance of about thirty jet widths downstream of the jet nozzle and that, in the self-preserving region of the jet, the distributions of the turbulent intensities and shear stress across the jet are very similar to those found in the plane wake. The distribution of the intermittency factor, however, is found to be more like that found in an axi-symmetric jet than in a plane wake. The turbulent energy balance also shows important differences to that of the wake flow. The unsteady irrotational flow outside the turbulent shear layer is investigated and it is found that the experimental results agree with the predictions of the theories of Phillips (1955) and Stewart (1956). Some comments are also made on the eddy structure and the applicability of the simple theories of turbulence.

The influence of Reynolds number on a plane jet

“…The two data sets agree closely within the midfield, i.e., x / h Յ 60, but exhibit some differences in the far field ͑for x / h Ͼ 60͒. Likewise, the results from smoothly contracting nozzles of Gutmark and Wygnanski 10 and Bradbury 8 for relatively high nozzle aspect ratios ͑AR= 39 and 40͒ measured at identical Reynolds numbers ͑Re h = 30 000͒ differ significantly. These differences can probably be attributable to the use of a coflow by Bradbury 8 ͑for a coflow to jet velocity ratio of Ϸ16%͒.…”

“…[2][3][4][5][6][7][8][9][10] A practical plane jet is produced by a rectangular slot of dimensions w ϫ h, with w ӷ h ͑where w and h are the slot's long and short sides͒ bounded by two parallel plates, known as sidewalls, attached to the slot's short sides. The presence of sidewalls restrict the jet from developing in the direction normal to the short sides, so that the flow develops statistically two dimensionally up to a certain downstream distance, provided that the nozzle aspect ratio, AR͑ϵw / h͒, is sufficiently large.…”

Numerical Simulation of Fluidic Actuators for Flow Control Applications

“…Note that the maximum levels for the perturbation velocities for the blocked feedback channel configuration are approximately 20-25% of the corresponding mean velocity levels, which is typical of free jets. 24,25 On the other hand, the perturbation velocities for the baseline 124D sweeping jet are almost twice as large, which indicates that the sweeping jets are more energetic in nature, and are accompanied by higher levels of flow unsteadiness.…”

Comparison of flow and dispersion properties of free and wall turbulent jets for source dynamics characterisation

“…13. The velocity profiles at different distances behind the jet are compared with theoretical curves of Goertler (Abramovich, 1963), Tollmien (Abramovich, 1963) and Bradbury (1965). The wall jet results show a profile similar to the free jet reported earlier on.…”