Abstract
This paper addresses the numerical simulation of thermo-fluid characteristics of triangular jets. The results of spatially developing, three dimensional jets from isosce les and equilateral nozzles at different Reynolds numbers and distances between jets are presented. The system of governing equations, subject to the proper boundary condi tions is solved with the finite volume method with collo cated grid arrangement. SIMPLEC algorithm was used for the pressure-velocity coupling to discrete the governing equations of flow and energy. The turbulent stresses are approximated using k - e model. The velocity and tempera ture fields are presented and rates of their decay at jet cen terline are noted. The velocity vectors of main flow and secondary flow are illustrated. Also, the effect of different vertex angles on mixing in triangular cross-section jets is considered. The vertex angles that were considered for this work were 30 to 120 degree. The results showed that the jet entrains more with equilateral cross sections. Special attention has been drawn to the influence of the Reynolds number (based on hydraulic diameter) as well as the inflow conditions on the evolution of the triangular jet. The inflow conditions have considerable influence on the jet character istics. The flow pattern results show strong mixing and flow entrainment from free boundaries into the jet. In comparison with single triangular jet mass entrainment from free boundaries is larger and also potential core is smaller. http://dx.doi.org/10.5755/j01.mech.17.2.330
Highlights
Free jets represent a very good benchmark for research in the physics of turbulent fluid flow
One of the advantages of sharp-edged non-circular geometries, such as the triangular nozzle, is that large-scale turbulence is generated along the sides of the nozzle, while small-scale turbulence is generated at the vertices
The solution procedure has been validated using a set of experiment data of the triangular jet (Mi et al and Quinn) those selected from available literature and compared with results of numerical simulation
Summary
Free jets represent a very good benchmark for research in the physics of turbulent fluid flow. Mi et al [4] experimentally studied nine nozzle shapes of circular and noncircular jets They investigated the mean and fluctuations of centerline velocity at a Reynolds number of 1.5u104. Quinn [7] covered out experimental investigation of isosceles triangular jet and showed that it has the best mixing enhancement characteristics among noncircular turbulent jets. Miller et al [9] studied noncircular jets numerically using direct numerical simulation They investigated the fluid dynamics of the flow field and combustion of a variety of noncircular jets at low specified Reynolds number. Influence of jet cross-section on the flow and combustion were studied and showed that the triangular jets have higher mixing ability compared with the other noncircular jets. Quinn [10] experimentally studied a triangular crosssection free jet and presented the contours of average and fluctuating velocity component
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