The effect of coflows on a turbulent jet impacting on a plate

The study examines the dynamic and the turbulent behavior of a plane jet impinging normally on a flat target plate in a flow at rest or in a coflow stream. First, numerical and experimental investigations of the characteristics of a turbulent plane jet impinging on a flat surface in still air are depicted. The measurements are conducted using Particle Image Velocimetry (PIV). A comparison has been carried out between numerical results of three turbulence closure models (k-epsilon standard model, RNG k-epsilon model and a second-order model RSM) and experimental data. It has been found that the second order turbulence model (RSM) reasonably predicts the mean flow properties of the flow field. Next, a numerical study of the flow field of an impinging jet in a coflow stream is conducted. The study of the jet in a no-directed coflow stream shows the presence of a phenomenon of recirculation near the flat plate. In addition, the study focuses on the influence of the coflow velocity ratio on the behavior of an impinging jet and the influence of the directed co-flow on various physical parameters such as the mean and the turbulent quantities. The results clearly show that the coflow stream imposed noticeable restrictions on the spreading of the impinging jet and decreases considerably the entrainment of air jet. (C) 2016 Elsevier Inc. All rights reserved.