CFD Study of Effects of Geometry Variations on Flow in a Nozzle

Abstract

Reynolds-Averaged Navier-Stokes simulations have been performed to investigate the effect of nozzle geometry on the turbulence characteristics of incompressible fluid flow through nozzles at Reynolds number of approximately 50,000. Four nozzles have been considered: a baseline nozzle and three modified nozzles (extended, grooved and ringed). The flow in these nozzles has been simulated using different turbulence closure models, including Spalart-Allmaras, variants of k -ε and k -ω, and the Reynolds Stress Model (RSM). By comparison to experimental data, it is shown that the RSM produces more accurate results for the prediction of turbulent fluctuations. The presence of a ring significantly increases both the turbulence intensity and mean velocity at the exit, and requires a much higher inlet pressure to move the fluid through the nozzle. On the other hand, cutting a groove near the exit or extending the nozzle has little effect on the exit flow characteristics.

Optimizing the velocity of ring shape parameter for designing the nozzles using CFD

“…Therefore, it is stated that velocity increases as the surface area of nozzle decreases. The result stating that there is significant positive effect of increase in pressure on velocity is in agreement with Yu et al [26]. Moreover, the analysis also showed that presence of a ring significantly increases mean velocity at the exit and increased inlet pressure is required to move the fluid through the nozzle.…”

Current Advances in Ejector Modeling, Experimentation and Applications for Refrigeration and Heat Pumps. Part 1: Single-Phase Ejectors

“…Recognizing the important influence of nozzles outlet conditions on downstream flow in engineering applications, several other numerical studies were performed. Yu et al [244] Hemidi et al [242] use of Standard k-ε and k-ω SST models with air indicated that Standard k-ε model predicted both on-design and off-design experiments for entrainment and compression with less than 10% discrepancy.…”

“…Recognizing the important influence of nozzles outlet conditions on downstream flow in engineering applications, several other numerical studies were performed. Yu et al [244] investigated the effect of nozzle configuration on turbulence characteristics of water flow in order to find out how the flow field changed with nozzle exit geometry. Four nozzle shapes (baseline, extended, grooved and ringed) were simulated numerically using different turbulence models out of which the RSM model was found to best represent experimental turbulent fluctuations data in terms of turbulence intensity, kinetic energy, dissipation rate and velocity.…”

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“…Today, CFD models are standard tools of the scientists, which save the time and cost of experiment, however the result of the simulation is necessary at least partially to compare with experiment or basic theory. Many author use CFD software for investigation of the fluid flow through nozzle [4], e.g. distribution of the air in the building or room for air-condition [5][6], cavitation in the fuel injection nozzles [7] or fluid flow together with heat transfer of the impinging stream on the cooled or heated wall [8].…”