Calculating air concentration along a free jet

Amin Salamatian, Roghayeh Ahmadpour, Morteza Marosi, Hamed Sarkardeh

Tuesday 30 june 2015

12:42 - 12:45h at Europe 1 & 2 (level 0)

Themes: (T) Water engineering, (ST) Computational methods, Poster pitches

Parallel session: Poster pitches: 5E. Engineering - Computional

In high dams, free jets are generated at the end of chutes or at bottom outlets to direct the discharge to a plunge pool, where the residual flow energy is dissipated. Typically, the bulk of water in free jets disintegrates and expands in the air which cause decreasing the jet density by entraining the air. By generating an air-water flow and therefore decreasing jet density, it is expected that scour potential be reduced at the downstream of the jet. One scenario about air entry mechanism is described by standing small volume of the air inside the small vortices at the water surface. Therefore, by going the air inside of the water flow, it is possible transferring to the downstream by the jet flow. In the present analytical and numerical study, the air concentration is calculated along a free jet in different flow characteristics. To simulate the air-water flow jet, the Flow 3D software is used. This numerical model based on the Navier-Stokes equations, uses the VOF method to model two-phase flow (water and air) and LES method to model the turbulence phenomenon. Finally, the analytical and numerical modeled air concentration profiles along the height and length of a jet, the results has been compared with the experimental data. The results showed that the numerical and analytical models are able very well to simulate the air concentration profiles along the height and length of a free jet.