EFFECT OF REYNOLDS NUMBER ON THE TURBULENT FLOW STRUCTURE IN THE NEAR-WALL REGION OF AN IMPINGING ROUND JET

Time-Resolved Particle Image Velocimetry was used to study the effect of the Reynolds number on the turbulent flow structure of a submerged water jet impinging normally on a smooth and flat surface. A fully developed turbulent jet and a semi-confined flow configuration ensured properly characterized boundary conditions allowing for straightforward assessment of turbulence models and numerical schemes. The Reynolds number based on jet mean exit velocity was 5,000, 10,030 and 15,050 while the pipe-to-plate separation distance was fixed at two diameters. Turbulent velocity fields are presented using Reynolds decomposition into mean and fluctuating components while Proper Orthogonal Decomposition (POD) analysis identified the most energetic coherent structures in the stagnation and wall-jet regions.