Flow structure, heat transfer and pressure drop in varying aspect ratio two-pass rectangular smooth channels

Abstract

Two-pass channels are used for internal cooling in a number of engineering systems e.g., gas turbines. Fluid travelling through the curved path, experiences pressure and centrifugal forces, that result in pressure driven secondary motion. This motion helps in moving the cold high momentum fluid from the channel core to the side walls and plays a significant role in the heat transfer in the channel bend and outlet pass. The present study investigates using Computational Fluid Dynamics (CFD), the flow structure, heat transfer enhancement and pressure drop in a smooth channel with varying aspect ratio channel at different divider-to-tip wall distances. Numerical simulations are performed in two-pass smooth channel with aspect ratio W in /H = 1:3 at inlet pass and W out /H = 1:1 at outlet pass for a variety of divider-to-tip wall distances. The results show that with a decrease in aspect ratio of inlet pass of the channel, pressure loss decreases. The divider-totip wall distance (W el ) not only influences the pressure drop, but also the heat transfer enhancement at the bend and outlet pass. With an increase in the divider-to-tip wall distance, the areas of enhanced heat transfer shifts from side walls of outlet pass towards the inlet pass. To compromise between heat transfer and pressure drop in the channel, W el /H = 0.88 is found to be optimum for the channel under study.

Effect of Orientation and Aspect Ratio of an Internal Flat Plate on Natural Convection in a Circular Enclosure

“…The coefficient obtained under various resolutions does not show much difference, i.e., a relative difference of less than 0.2% between the results obtained at the 256 × 128 and 512 × 256 grid, thus the 512 × 256 grid was deemed sufficient for this simulation. In this work, we performed a grid sensitivity study for the H•W/D 2 = 0.04 cases with a square cylinder (H/D = W/D = 0.2), a vertically placed plate with H/D = 0.8, and a horizontally placed plate with W/D = 0.8 using the 256 × 256, 512 × 256, and 512 × 512 grids following the manner described in [28,29]. The computed mean Nusselt numbers on the enclosure surface are given in Table 3.…”

Influence of turn geometry on turbulent fluid flow and heat transfer in a stationary two-pass square duct

“…They also reported that heat transfer in the turn region of a straight-corner and circular turn cases is the highest and the lowest respectively. Siddique et al [13] were performed a numerical study on flow structures, heat transfer and pressure drop in a two-pass rectangular duct with varying aspect ratio. An inlet pass having an aspect ratio of 1:3 and square outlet pass with different divider-to-tip wall distances has been used for their study.…”

Effect of rotation on forced convection in wavy wall channels

“…The friction coefficient is employed to evaluate the hydrodynamic performance of the fluid flow inside the wavy channel and is defined as [28], [29] :…”

“…It is obvious that rotation has a substantial impact on the heat transfer enhancement because it can cause flow spreading in the spanwise direction and hence enhancing the spanwise heat transfer. The normalized Nusselt number ( ) is used to evaluate the performance of heat transfer from a surface [28], [29], [33].…”