Large Eddy Simulation of Spray Injection to Turbulent Duct Flow from a Slit Injector

A particle-laden turbulent flow in a square duct is predicted using large eddy simulation (LES). The simulation is performed for a Reynolds number of 35,500, and correctly predicts the existence of secondary flows and their effects on the mean flow. The results are also in good qualitative agreement with experimental data obtained at different Reynolds numbers. One-way coupling is assumed between solid particles and the fluid, and a particle equation of motion, including Stokes drag, lift, buoyancy and gravity force terms, solved using a Lagrangian particle tracking technique. Three sizes of particle (1, 50 and 100 μm) are considered, and results demonstrate that size has a significant effect on particle dispersion and deposition in the duct flow. As particle size increases, therefore, they tend to settle on the floor of the duct, with less dispersion in the fluid phase. The study demonstrates the usefulness of LES for nuclear waste processing applications since secondary flows occur in many practically-relevant flows, and since it is desirable that the two-phase waste mixture is kept as homogeneous as possible to prevent, or at least discourage, the settling out of solid particles to form a bed which can promote pipe blockages.

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Large-eddy simulation of compressible rectangular duct flow

PAMM ◽

10.1002/pamm.200310160 ◽

2003 ◽

Vol 2 (1) ◽

pp. 352-353 ◽

Cited By ~ 2

Author(s):

B. Rembold ◽

L. Kleiser

Keyword(s):

Large Eddy Simulation ◽

Duct Flow ◽

Rectangular Duct ◽

Eddy Simulation ◽

Large Eddy

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A Large Eddy Simulation (LES) of Plate-Fin and Tube Heat Exchangers

2010 14th International Heat Transfer Conference, Volume 4 ◽

10.1115/ihtc14-22030 ◽

2010 ◽

Author(s):

Li-Zhi Zhang

Keyword(s):

Heat Transfer ◽

Large Eddy Simulation ◽

Vortex Shedding ◽

Heat Exchangers ◽

Temporal Variations ◽

Dominant Factor ◽

Normal Velocity ◽

Duct Flow ◽

Eddy Simulation ◽

Large Eddy

Plate-fin and tube heat exchangers are extensively studied both experimentally and numerically. With a large eddy simulation technique (LES), this study performs a detailed investigation of the temporal oscillations of streamwise, spanwise and normal velocity components in the exchanger passage and their effects on heat transfer between fins and fluid. Focus is on the instability and transitional behavior of fluid flow in the exchanger. Temporal variations of instantaneous velocity found that even under very low frontal velocities, the fluid exhibits some degree of oscillations, which change from periodic, regular fluctuations to aperiodic, chaotic turbulence with increasing Reynolds numbers. Contrary to the vortex shedding in a bare tube bank, the flow in the exchanger is more like a duct flow, with steady vortexes formed behind each tube. A frequency spectrum analysis of velocity fluctuations further proves that vortex shedding is not the dominant mechanism for momentum and heat transfer. Rather, tube induced oscillations are the dominant factor.

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