Investigation of Flow Dynamics in the Beginning of Propagation of a Turbulent Jet

The succession of variation in the flow parameters in the beginning of formation of a submerged turbulent jet is investigated at the subsonic outflow velocity. The numerical simulation based on the LES technique and the determination of flow parameters using low-inertial measuring tools are used. The investigation shows that at the initial instants of time the properties of flow are caused by separation of flow from the nozzle edge which is accompanied by formation of large toroidal vortices outside the jet in its initial cross-section. In this case, considerable inhomogeneities in the static pressure distribution appear in the flow developed. The maximum inhomogeneities (rarefaction and excess in the static pressure with respect to the atmospheric pressure) are equal approximately to the velocity head (dynamic pressure) in the initial jet cross-section and decrease along the flow. In the case of steady-state flow, the extremum rarefactions in the traveling quasi-periodic inhomogeneities of the static pressure distribution are conserved at the level of 10-20% of the velocity head in the jet source. As a whole, the results of mutual comparison of the calculated data in different outflow regimes and the data obtained experimentally are in satisfactory agreement and confirm the general conclusions of the earlier investigations.