In the present study, a commercial finite volume package ANSYS FLUENT 14.5 has been used to determine thermo-hydraulic performance of two different vortex generator (VG) configurations, namely, flow-up and flow-down, located in triangular ducts. A comprehensive literature survey on flow-up and flow-down configurations has shown that there are completely opposite results obtained in terms of performance of the two configurations. In some studies, flow-up configuration showed better performance characteristics over flow-down configuration while in other studies flow-down configuration was found better. This has been motivated the present authors to make a study covering the two VG configurations to find out which one has a better performance over the other one. Therefore flow and thermal fields together with the secondary flow induced by the two VG configurations have been analyzed extensively. The geometry comprised of double row of VGs located on the slant surfaces of equilateral triangular ducts. The angle of inclination of the VGs made with the flow direction is 30°. The results show that flow-down configuration has a 40.65% higher thermo-hydraulic performance over the flow-up configuration for Re=5000. It is also shown that the heat is transferred at a further downstream distance allowing in a reduction in the number of VGs to be used in of flow down case.
In this study, the influence of spanwise positions of vortex generators on the fin performance is determined numerically by considering global and local flow and heat transfer fields. The vortex generators are located on the inclined surfaces of equilateral triangular fins and the spanwise distances between them are altered as much as possible depending on the extents of the triangular duct. “RNG k-ɛ” turbulence model with “Enhanced wall treatment” option is determined as the best turbulence model to predict the flow fields inside the triangular fins with built-in vortex generators, for Reynolds number of 5000. It is found that the best performance is achieved when the spanwise distance between the common flow up and common flow down type vortex generator pairs and the triangular duct base are equal to 0.23 and 1.11 times the vortex generator length, respectively. The optimum spanwise distance between the vortex generators is determined as 0.88 times the vortex generator length. The determined values reinforced the secondary flow interactions including mixing of hot and cold fluids, generation of turbulence, swirling motion of vortices, and interaction of vortices with the main flow. The obtained results are useful in designing triangular heat exchangers with built-in delta-winglet type vortex generators.
Three-dimensional printing, also known as additive manufacturing, refers to the processes used to synthesize a three-dimensional object in which successive layers of an object are created to create an object under computer control. Objects can create almost any shape or geometry. It is created using digital model data from another electronic data source or 3D model. In this study, the process of reproducing a part is made by pouring epoxy into a mold formed by taking the mold of spur gear wheels produced in a 3D printer with the silicone molding technique. A comparison was made for dimensional accuracy of all parts, Computer Aided Design data, three-dimensional parts and parts reproduced using silicone molds. Successful manufacturing processes have been carried out with experimental studies. It has been determined that the diameter of the top of the tooth can be manufactured with a measurement difference of 2.5% and 5% of the root diameter. It has been demonstrated that it can be used successfully in manufacturing processes and restoration works where measurement tolerances are allowed up to 5% on average. It has been determined that it is the cheapest method applicable to repair operations that can be used once, as it can be realized without the need for professional machinery-equipment and personnel.
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