# Near-wall and Turbulence Behavior of Swirl Flows through an Aerodynamic Nozzle

## DOI:

https://doi.org/10.38032/jea.2020.02.003## Keywords:

Turbulent, Nozzle, Swirl, Aerodynamic, CFD, Pressure## Abstract

It is often a challenge to achieve uniform flow in turbulent swirl flow and to predict the flow within the nozzle as measurement diagnostics face difficulty to capture both mean flow and turbulence. The purpose of this study is to numerically investigate the near wall flow characteristics and turbulent behavior for the effect of different tangential inlet numbers of an incompressible turbulent swirl air jet. In this regard, axial-plus-tangential flow based swirling nozzle is considered for the simulation using finite volume method, where turbulence is approximated by the Shear Stress Transport (SST) *k-ω* model. The results show that axial and tangential velocity at the wall vicinity response the most. Moreover, the turbulent flow characteristic for no swirl flow is nearly uniform, but for swirl flow it fluctuates abruptly near the inlet section where the swirl has introduced. The skin friction coefficient for 2TP is the maximum for swirl flow and for no swirl condition the skin friction coefficient is nearly uniform. Due to the swirl introduction the pressure drop characteristics near the nozzle center response quickly and near the wall vicinity this property change slowly. The magnitude of swirl decay fluctuates before the nozzle converging section however after the nozzle converging section the swirl decay is nearly constant. The local swirl near the inlet is highly unpredictable although after the nozzle converging section the local swirl profile is nearly similar for 2TP, 3TP and 4TP.

## References

Sloan, D.G., Smith, P.J. and Smoot, L.D., 1986. Modeling of swirl in turbulent flow systems. Progress in Energy and Combustion Science, 12(3), pp.163-250.

Rose, W.G., 1962. A swirling round turbulent jet, Journal of Applied Mechanics, vol.29, Trans. ASME, vol. 84, Series E, pp. 616-625.

Toh, K., Honnery, D. and Soria, J., 2010. Axial plus tangential entry swirling jet. Experiments in Fluids, 48(2), pp.309-325.

Ahmed, Z.U., 2016. An experimental and numerical study of surface interactions in turbulent swirling jets. PhD Thesis, Edith Cowan University, Australia.

Gore, R.W. and Ranz, W.E., 1964. Backflows in rotating fluids moving axially through expanding cross sections. AIChE Journal, 10(1), pp.83-88.

Jafari, M., Farhadi, M. and Sedighi, K., 2017. An experimental study on the effects of a new swirl generator on thermal performance of a circular tube. International Communications in Heat and Mass Transfer, 87, pp.277-287.

Markal, B., 2018. Experimental investigation of heat transfer characteristics and wall pressure distribution of swirling coaxial confined impinging air jets. International Journal of Heat and Mass Transfer, 124, pp.517-532.

Yajnik, K.S. and Subbaiah, M.V., 1973. Experiments on swirling turbulent flows. Part 1. Similarity in swirling flows. Journal of Fluid Mechanics, 60(4), pp.665-687.

Chang, F. and Dhir, V.K., 1994. Turbulent flow field in tangentially injected swirl flows in tubes. International journal of heat and fluid flow, 15(5), pp.346-356.

KITO, O. and KATO, T., 1984. Near wall velocity distribution of turbulent swirling flow in circular pipe. Bulletin of JSME, 27(230), pp.1659-1666.

Kitoh, O., 1991. Experimental study of turbulent swirling flow in a straight pipe. Journal of Fluid Mechanics, 225, pp.445-479.

Buschmann, M.H., Indinger, T. and Gad-el-Hak, M., 2009. Near-wall behavior of turbulent wall-bounded flows. International Journal of Heat and Fluid Flow, 30(5), pp.993-1006.

Ahmed, Z.U., Al-Abdeli, Y.M. and Guzzomi, F.G., 2016. Corrections of dual-wire CTA data in turbulent swirling and non-swirling jets. Experimental Thermal and Fluid Science, 70, pp.166-175.

Ahmed, Z.U., Khayat, R.E., Maissa, P. and Mathis, C., 2012. Axisymmetric annular curtain stability. Fluid Dynamics Research, 44(3), p.031401:1-23.

Ahmed, Z.U., Khayat, R.E., Maissa, P. and Mathis, C., 2013. Non-axisymmetric annular curtain stability. Physics of Fluids, 25(8), p.082104:1-37.

Lu, P. and Semião, V., 2003. A new second‐moment closure approach for turbulent swirling confined flows. International journal for numerical methods in fluids, 41(2), pp.133-150.

Tsai, J.H., Lin, C.A. and Lu, C.M., 1995. Modelling dump combustor flows with and without swirl at the inlet using Reynolds stress models. International Journal of Numerical Methods for Heat & Fluid Flow, vol. 5, no. 7, pp. 577–588.

Gorman, J.M., Sparrow, E.M., Abraham, J.P. and Minkowycz, W.J., 2016. Evaluation of the efficacy of turbulence models for swirling flows and the effect of turbulence intensity on heat transfer. Numerical Heat Transfer, Part B: Fundamentals, 70(6), pp.485-502.

Saqr, K.M. and Wahid, M.A., 2014. Effects of swirl intensity on heat transfer and entropy generation in turbulent decaying swirl flow. Applied thermal engineering, 70(1), pp.486-493.

Nouri-Borujerdi, A. and Kebriaee, A., 2012. Simulation of turbulent swirling flow in convergent nozzles. Scientia Iranica, 19(2), pp.258-265.

Najafi, A.F., Saidi, M.H., Sadeghipour, M.S. and Souhar, M., 2005. Numerical analysis of turbulent swirling decay pipe flow. International communications in heat and mass transfer, 32(5), pp.627-638.

Islam, Md. M., Tasnim, S., and Ahmed, Z. U., 2017. Numerical study of a swirl nozzle at moderate swirl number, International Conference on Mechanical Engineering and Renewable Energy, 20-22 December, Chittagong, Bangladesh.

Islam, S. M, Khan, M. T., Ahmed, Z. U., 2020. Effect of design parameters on flow characteristics of an aerodynamic swirl nozzle, Progress in Computational Fluid Dynamics, In press.

Khan, M. H. U., and Ahmed, Z. U., 2019. Fluid flow and heat transfer characteristics of multiple swirling impinging jets at various impingement distances, International Journal of Thermofluid Science and Technology, vol. 6, no. 4, pp. 19060403:1-12.

Ahmed, Z. U., Al-Abdeli, Y. M., 2017. Flow characteristics due to jet impact at low intensity, In: Proceedings of Int. Conf. Engineering, Research, Innovation and Education, Sylhet, Bangladesh, 156, p. 1-6.

Debnath, S., Khan, M.H.U. and Ahmed, Z.U., 2020. Turbulent Swirling Impinging Jet Arrays: A Numerical Study on Fluid Flow and Heat Transfer. Thermal Science and Engineering Progress, p.100580.

Ahmed, Z.U., Khan, M.H.U., Khayat, R.E. and Tasnim, S., 2018, July. Effect of flow confinement on the hydrodynamics and heat transfer characteristics of swirling impinging jets. In AIP Conference Proceedings (Vol. 1980, No. 1, p. 040008). AIP Publishing LLC.

Thomas, B.K., Ahmed, Z.U., Al-Abdeli, Y.M. and Matthews, M.T., 2013. The optimisation of a turbulent swirl nozzle using CFD. Proceedings of the Australian Combustion Symposium, November 6-8, Perth, Australia.

Menter, F.R. and Egorov, Y., 2010. The scale-adaptive simulation method for unsteady turbulent flow predictions. Part 1: theory and model description. Flow, Turbulence and Combustion, 85(1), pp.113-138.

Ahmed, Z.U., Al-Abdeli, Y.M. and Matthews, M.T., 2015. The effect of inflow conditions on the development of non-swirling versus swirling impinging turbulent jets. Computers & Fluids, 118, pp.255-273.

Ahmed, Z.U., Al-Abdeli, Y.M. and Guzzomi, F.G., 2017. Flow field and thermal behaviour in swirling and non-swirling turbulent impinging jets. International Journal of Thermal Sciences, 114, pp.241-256.

## Downloads

## Published

## How to Cite

*Journal of Engineering Advancements*,

*1*(02), 43–52. https://doi.org/10.38032/jea.2020.02.003

## Issue

## Section

## License

Copyright (c) 2020 Md Tanvir Khan, Sharif M. Islam, Zahir U. Ahmed

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.