Turbulence measurements in the impinging region of a circular jet

Abstract

This note presents the results of turbulence measurements in the impinging region of a circular jet of diameter d with a Reynolds number of 105 impinging on a smooth wall located at a distance H equal to 18.5d. Even though the impinging region starts approximately at x/H = 0.860 (where x is the distance from the nozzle), the mean velocity profiles were found to be similar for x/H up to about 0.930 when normalized by the local maximum value. The normalized profiles of the turbulent shear stress and normal stresses in the axial, radial, and circumferential directions were also found to be similar. The variation of the scales for these turbulence profiles was found to be gradual for x/H up to about 0.960 and then rapid near the impinging wall. The corresponding length scales also showed a similar type of variation. The measurements also show that turbulence in the impinging jet drops significantly very near the impinging wall.