Turbulent Flow Analysis in an Annular Diffuser Having a Rectangular Twisted Hub

Abstract:

Turbulent flow characteristics through a three-dimensional annular diffuser having a rectangular twisted hub RTH are investigated. The numerical analyses are performed to have more understanding of the physical behavior of the fluid flow. The numerical work is conducted using the RTH with three twist ratios (y/w = 0.6, 0.7, and 1) for a Reynolds number 128069. In the present study, the air is used as a working fluid. Computational Fluid Dynamics CFD, based on a finite volume method, is completed by utilizing the standard k-ε turbulence model. Velocity streamlines, velocity contours, and pressure contours plots are described to study the flow characteristics by utilizing different twist ratios (y\w). The analytical results reveal that RTH has a significant effect on the velocity and pressure characteristics. Findings show that the diffuser with the twist ratio (y\w = 0.6) produces more swirling and recirculation than (y\w = 0.7 and 1). Therefore, the RTH with a small twist ratio significantly enhances the distribution of the velocity and pressure because of the strong swirling generated through the flow.

• Periodical: Advances in Science and Technology (Volume 169)
• Pages: 67-72
• DOI: https://doi.org/10.4028/p-N0k2TU
• Online since: August 2025
• Authors: Ehan Sabah Shukri Askari*
• Keywords: Annular Diffuser, CFD, Rectangular Twisted Hub, Twist Ratio, Velocity Distribution

References

[1] W. Changcharoen, P. Somravysin, P. Promthaisong, P. Eiamsaard, K. Nanan and S. Eiamsaard. "Investigation of turbulent heat transfer in round tubs fitted with regularly spaced overlap duel twisted tape elements". Journal of Research and Applications in Mechanical Engineering. Vol. 3.2, (2015), p: 64 -74.

[2] F. Afsharpanah, K. Pakzad, M. Amirsoleymani and M. Aghajani Delavar. "Numerical study of heat transfer enhancement using perforated dual twisted tape inserts in converging-diverging tubes". Heat Transfer-Asian Research. Vol. 47, (2018), p: 754–767.

DOI: 10.1002/htj.21340

[3] M. Bhuyan, U. K. Deb, M. Shahriar and S. Acherjee. "Simulation of heat transfer in a tubular pipe using different twisted tape inserts". Open Journal of Fluid Dynamics ISSN Online: 2165-3860, (2017), p: 397-409.

DOI: 10.4236/ojfd.2017.73027

[4] D. Erdemir, S. Gunes, V. Ozceyhan and N. ALTuntop. "Numerical investigation of heat transfer enhancement and pressure drop in heat exchanger tube fitted with dual twisted tape elements". 10th WSEAS International Conference on Heat and Mass Transfer at Italy, Vol. 1, (2013), p: 167–172.

DOI: 10.1115/ht2012-58078

[5] L. Wang, P. Ni and G. Xi. "The effect of off‑center placement of twisted tape on flow and heat transfer characteristics in a circular tube". Scientific Reports, Vol. 11, (2021), p: 6844.

DOI: 10.1038/s41598-021-86285-0

[6] M. Ghalambaz, R. Mashayekhi, H. Arasteh, H. Muhammad Ali, P. Talebizadehsardari and W. Yaïci. "Thermo-hydraulic performance analysis on the effects of truncated twisted tape inserts in a tube heat exchanger". Symmetry, Vol. 12, (2020), p: 1652.

DOI: 10.3390/sym12101652

[7] M. Ghalambaz, H. Arasteh, R. Mashayekhi, A. Keshmiri, P. Talebizadehsardari and W. Yaïci. "Investigation of overlapped twisted tapes inserted in a double-pipe heat exchanger using two-phase nanofluid". Nano materials, Vol. 10, (2020), p: 1656.

DOI: 10.3390/nano10091656

[8] A. J. Abdulhamed, A. Al-Akam, W. J. Khudhayer and A. Sabri. "Tubular heat enhancement using twisted tape inserts with large holes". Energy Engineering, Vol.121, (2024), p: 273-290.

DOI: 10.32604/ee.2023.045583

[9] S. H. Ibrahim and Z. H. Naji. "Augmentation heat transfer in a circular tube using twisted tape inserts". Journal of Engineering and Sustainable Development, ISSN 2520-0917, Vol. 27, (2023), p: 511- 526.

DOI: 10.31272/jeasd.27.4.8

[10] D. Flórez-Orrego, W. Arias, D. López and H. Velásquez. "Experimental and CFD study of a single phase single-phase cone-shaped helical coiled heat exchanger: an empirical correlation". Proceedings of the 25th international conference on efficiency, cost, optimization, simulation and environmental impact of energy systems, (2012), P: 375–94.

[11] B. Djebedjian, M. Giat, J. P. Renaudeaux and M. A Rayan. "Numerical study of turbulent flow through equiangular annular diffusers". Proceeding of 5th International Conference of Fluid Mechanics, Cairo, (1995), p: 719-729.