DEVELOPMENT OF VORTEX STRUCTURE OF FLAT TURBULENT JET LIMITED BY A FRONT

Abstract

In this paper, the influence of friction resistance of face plates on the regularities of the development of a flat free jet was experimentally investigated. The work is devoted to an experimental study, the possible types of development of large-scale vortices on the initial part of a flat jet bounded by end walls, and their influence on the profiles of the averaged flow of the jet are considered. To calculate the effect of friction resistance of the end walls on the attenuation intensity of a flat free turbulent jet, the patterns of resistance change on the wall were experimentally determined. Due to the high level of jet turbulence, it was expected that the boundary layer on the end walls should be turbulent over almost the entire surface of the face plates. However, it was shown in the work that laminar, turbulent, and transition layers may actually exist on the end surfaces, depending on the specific conditions. According to experimental data, it was found that the change in the friction drag coefficient coincides with the theoretical dependence for a uniform flow around the plate with a laminar boundary layer at the front face of the jet at and the initial velocity m / s along the entire length of the jet to 100 calibers. It has been revealed that laminar, turbulent and transition layers may exist on the end surfaces depending on the specific conditions. Empirical expressions for changing the maximum jet velocity are obtained.

Keywords: nozzle, free jet, turbulent flow, experimental studу, bounding plates.