## THERMAL SCIENCE

International Scientific Journal

### VISUALIZATION OF FLOW CHARACTERISTICS BETWEEN THE RIBBED PLATES VIA PARTICLE IMAGE VELOCIMETRY

**ABSTRACT**

Heat transfer is considerably influenced by flow stagnation, separation and reattachment regions due to the ribbed plates. Placing the ribs such as fins, turbulators that trigger the flow separation, enhances the heat transfer inside the channel by increasing the turbulence intensity. The flow separation is caused by disturbing the thermal and hydrodynamic development lengths. Moreover, these ribs also make an impact that increases the heat transfer by enlarging the heat transfer area. However, the ribs lead to the increment of the required pumping power in the meantime due to the increasing pressure loss in such systems. This aforementioned method is used for the heat exchangers, the solar collectors, the cooling of electronic devices. The investigation of the flow characteristics is very crucial to understand the heat transfer mechanism in the ducts for this reason. In the present paper, the flow characteristics between the plates have been experimentally re-searched. Particle image velocimetry system in the open water channel of Selcuk University Advanced Technology Research and Application Center has been used. The smooth plates have been taken as the reference model and used for the comparison with the plates having the rectangular cross-sectional ribs. The ribs with various heights of 0.1 ≤ h′ = h/H ≤ 0.3 have been symmetrically placed on the internal surfaces of the plates via several spacing values of 0.5 ≤ S′ = S/H ≤ 1 for varying Reynolds numbers as 10000 ≤ Re ≤ 20000. As a result, the flow characteristics have been given in terms of the contour graphics for velocity vector field, velocity components and vorticity.

**KEYWORDS**

PAPER SUBMITTED: 2018-07-27

PAPER REVISED: 2019-07-05

PAPER ACCEPTED: 2019-07-19

PUBLISHED ONLINE: 2019-08-10

**THERMAL SCIENCE** YEAR

**2021**, VOLUME

**25**, ISSUE

**Issue 1**, PAGES [171 - 179]

- Sherry, M. J., Flow Separation Characterisation of a Forward Facing Step Immersed in a Turbulent Boundary Layer, Proceedings, 6th International Symposium on Turbulence and Shear Flow Phenomena, Seoul, South Korea, 2009, pp. 1325-1330
- Timuralp, C., Altac, Z., Investigation of Combined Heat Transfer and Laminar Fluid Flow in Two and Three Dimensional Ducts with an Open Cavity, Journal of Thermal Science and Technology, 37 (2017), 2, pp. 33-47
- Aung, W., An Experimental Study of Laminar Heat Transfer Downstream of Backsteps, Journal of Heat Transfer, 105 (1983), 4, pp. 823-829
- Mushahet, K. S., Simulation of Turbulent Flow and Heat Transfer over a Backward-Facing Step with Ribs Turbulators, Thermal Science, 15 (2011), 1, pp. 245-255
- Mayle, R. E., Pressure Loss and Heat Transfer in Channels Roughened on Two Opposed Walls, Journal of Turbomachinery, 113 (1991), 1, pp. 60-66
- Webb, B., Ramadhyani, S., Conjugate Heat Transfer in a Channel with Staggered Ribs, International Journal of Heat and Mass Transfer, 28 (1985), 9, pp. 1679-1687
- Liu, H., Wang, J., Numerical Investigation on Synthetical Performances of Fluid Flow and Heat Transfer of Semiattached Rib-Channels, International Journal of Heat and Mass Transfer, 54 (2011), pp. 575-583
- Wongcharee, K., et al., Numerical Investigation of Flow Friction and Heat Transfer in a Channel with Various Shaped Ribs Mounted on Two Opposite Ribbed Walls, International Journal of Chemical Reactor Engineering, 9 (2011), 1, A26
- Desrues, T., et al., Numerical Prediction of Heat Transfer and Pressure Drop in Three-Dimensional Channels with Alternated Opposed Ribs, Applied Thermal Engineering, 45 (2012), pp. 52-63
- Xie, G., et al., Computational Fluid Dynamics Modeling Flow Field and Side-Wall Heat Transfer in Rectangular Rib-Roughened Passage, Journal of Energy Resources Technology, 135 (2013), 4, 042001
- Marocco, L., Franco, A., Direct Numerical Simulation and RANS Comparison of Turbulent Convective Heat Transfer in a Staggered Ribbed Channel with High Blockage, Journal of Heat Transfer, 139 (2017), 2, 021701
- Hwang, J-J., Liou, T-M., Effect of Permeable Ribs on Heat Transfer and Friction in a Rectangular Channel, Journal of Turbomachinery, 117 (1995), 2, pp. 265-271
- Lopez, J., et al., Heat Transfer in a Three-Dimensional Channel with Baffles, Numerical Heat Transfer Part A Applications, 30 (1996), 2, pp. 189-205
- Tafti, D., Evaluating the Role of Subgrid Stress Modeling in a Ribbed Duct for the Internal Cooling of Turbine Blades, International Journal of Heat and Fluid Flow, 26 (2005), 1, pp. 92-104
- Pourmahmoud, N., et al., The Effects of Longitudinal Ribs on Entropy Generation for Laminar Forced Convection in a Micro-Channel, Thermal Science, 20 (2016), 6, pp. 1963-1972
- Tokgoz, N., et al., Investigation of Flow Characteristics and Heat Transfer Enhancement of Corrugated Duct Geometries, Applied Thermal Engineering, 118 (2017), pp. 518-530
- Promvonge, P., Thianpong, C., Thermal Performance Assessment of Turbulent Channel Flows over Different Shaped Ribs, Int. Comm. in Heat and Mass Transfer, 35 (2008), 10, pp. 1327-1334
- Skullong, S., et al., Effects of Rib Size and Arrangement on Forced Convective Heat Transfer in a Solar Air Heater Channel, Heat and Mass Transfer, 51 (2015), 10, 1475-1485
- Vanaki, S. M., Mohammed, H., Numerical Study of Nanofluid Forced Convection Flow in Channels Using Different Shaped Transverse Ribs, Int. Comm. in Heat and Mass Transfer, 67 (2015), pp. 176-188
- Yang, W., et al., Experimental Study on the Heat Transfer Characteristics of High Blockage Ribs Channel, Experimental Thermal and Fluid Science, 83 (2017), pp. 248-259
- Kilicaslan, I., Sarac, H. I., Enhancement of Heat Transfer in Compact Heat Exchanger by Different Type of Rib with Holographic Interferometry, Experimental Thermal and Fluid Science, 17 (1998), 4, pp. 339-346
- Pehlivan, H., et al., Experimental Study of Forced Convective Heat Transfer in a Different Arranged Corrugated Channel, Int. Comm. in Heat and Mass Transfer, 46 (2013), pp. 106-111
- Aslan, E., et al., Finite Volume Simulation for Convective Heat Transfer in Wavy Channels, Heat and Mass Transfer, 52 (2016), 3, pp. 483-497
- Yemenici, O., Umur, H., Experimental Aspects of Heat Transfer Enhancement over Various Flow Surfaces, Heat Transfer Engineering, 37 (2016), 5, pp. 435-442
- Nine, M. J., et al., Turbulence and Pressure Drop Behaviors around Semicircular Ribs in a Rectangular Channel, Thermal Science, 18 (2014), 2, pp. 419-430
- Sripattanapipat, S., Promvonge, P., Numerical Analysis of Laminar Heat Transfer in a Channel with Diamond-Shaped Baffles, Int. Comm. in Heat and Mass Transfer, 36 (2009), 1, pp. 32-38
- Ahmed, M., et al., Effects of Geometrical Parameters on the Flow and Heat Transfer Characteristics in Trapezoidal-Corrugated Channel Using Nanofluid, Int. Comm. in Heat and Mass Transfer, 42 (2013), pp. 69-74
- Dean, R., Reynolds Number Dependence of Skin Friction and Other Bulk Flow Variables in Two-Dimensional Rectangular Duct Flow, Journal of Fluids Engineering, 100 (1978), 2, pp. 215-22