Effect of attack angle on the flow around adjacent circular and rectangular prisms

Abstract

An experimental investigation has been carried out to clarify the flow structure around adjacent circular and rectangular prisms. The measurements of hot-wire for Re= 4.1 x 10³, 9.0 x 10³ and 1.5 x 10⁴, lift and drag force for Re = 1.0 x 10⁴, and in addition the flow visualization experiments for Re = 2.3 x 10³ have been performed in the range of 0° ≤ α ≤ 180°. The adjacent bodies consist of a circular cylinder having 9.5 mm diameter and a rectangular prism having 6 mm x 10 mm cross-section attached to the circular cylinder from its short side in all the cases. The hot wire measurement results showed that the Strouhal number has Reynolds number independence for Re = 4.1x10³, 9.0x10³, and 1.5x10⁴. Sudden peaks in St and lift coefficients are obtained for a similar reason that is reattachment of the separated shear layer in the vicinity of α = 60° and 174°. For the adjacent bodies compared with the bare circular cylinder, 40%, and 25% drag reduction is obtained at α = 0° and 174°, respectively. The obtained results show that the variations of lift coefficient, drag coefficient, and Strouhal number are strictly subjected to the attack angle.

Keywords

• Adjacent Bluff Bodies
• Circular Cylinder
• Rectangular prism
• Drag Coefficient
• Strouhal number

Hücum açısının temas halinde dairesel ve dikdörtgen prizma etrafındaki akış üzerine etkisi

Öz

Temas halindeki dairesel ve dikdörtgen prizmalar etrafındaki akış yapısını aydınlatmak için deneysel bir araştırma yapılmıştır. Re= 4.1 x 10³, 9.0 x 10³ ve 1.5 x 10⁴ için kızgın telle hız, Re = 1.0 x 10⁴ için kaldırma ve sürüklenme kuvveti ölçümleri ve ayrıca Re = 2.3 x 10³ için akış görüntüleme deneyleri 0° ≤ α ≤ 180° aralığında gerçekleştirilmiştir. Temas halindeki cisimler, 6 mm x 10mm kesite sahip dikdörtgen bir prizma ile 9.5mm çapına sahip dairesel bir silindirden oluşmaktadır. Kızgın tel ölçüm sonuçları, Strouhal sayısının Re = 4.1x10³, 9.0x10³ ve 1.5x10⁴ sayıları için Reynolds sayısından bağımsız olduğunu göstermiştir. Kaldırma ve Strouhal sayılarındaki ani pikler akış ayrılma tabakasının α = 60° ve 174° civarında yeniden tutunmasıyla ilgili aynı nedenden kaynaklanmaktadır. Temas halindeki cisimler ile sade silindir karşılaştırıldığında sürüklenme katsayısı α = 0° ve 174°'de sırasıyla %40 ve %25 azaltılmıştır. Elde edilen sonuçlar, kaldırma, sürüklenme katsayısı ve Strouhal sayısı değişimlerinin hücum açısına bağlı olduğunu göstermiştir.

Anahtar Kelimeler

• Temas halindeki cisimler
• Dairesel silindir
• Dikdörtgen prizması
• Sürüklenme katsayısı
• Strouhal sayısı

Kaynakça

1. K. Y. Billah and R. H. Scanlan, Resonance, Tacoma Narrows bridge failure, and undergraduate physics textbooks. American Journal of Physics, 59, 118–124, 1991. https://doi.org/10.1119/1.16590.
2. A. C. Khanduri, T. Stathopoulos and C. Bédard, Wind-induced interference effects on buildings — a review of the state-of-the-art. Engineering Structures, 20 617–630, 1998. https://doi.org/10.1016/S0141-0296(97)00066-7.
3. P. Burattini and A. Agrawal, Wake interaction between two side-by-side square cylinders in channel flow. Computers & Fluids, 77, 134–142, 2013. https://doi.org/10.1016/j.compfluid.2013.02.014.
4. A. Roshko, Experiments on the flow past a circular cylinder at very high Reynolds number. Journal of Fluid Mechanics, 10, 345–356, 1961. https://doi.org/10.1017/S0022112061000950
5. Y. Bao and J. Tao, The passive control of wake flow behind a circular cylinder by parallel dual plates. Journal of Fluids and Structures, 37, 201–219, 2013. https://doi.org/10.1016/j.jfluidstructs.2012.11.002.
6. S. Shukla, R. N. Govardhan and J. H. Arakeri, Flow over a cylinder with a hinged-splitter plate. Journal of Fluids and Structures, 25, 713–720, 2009. https://doi.org/10.1016/j.jfluidstructs.2008.11.004.
7. E. A. Anderson and A. A. Szewczyk, Effects of a splitter plate on the near wake of a circular cylinder in 2 and 3-dimensional flow configurations. Experiments in Fluids, 23, 161–174, 1997. https://doi.org/10.1007/s003480050098.
8. T. Igarashi, Drag reduction of a square prism by flow control using a small rod. Journal of Wind Engineering and Industrial Aerodynamics, 69,141–153, 1997. https://doi.org/10.1016/S0167-6105(97)00150-5

9. M. Sarioglu, Y. E. Akansu and T. Yavuz, Flow Around Rotatable Square Cylinder-Plate Body. AIAA Journal, 44, 1065–1072, 2006. https://doi.org/10.2514/1.18069.
10. J. M. Chen and C. H. Liu, Vortex shedding and surface pressures on a square cylinder at incidence to a uniform air stream. International Journal of Heat and Fluid Flow, 20, 592–597, 1999. https://doi.org/10.1016/S0142-727X(99)00047-8.
11. B. E. Lee, The effect of turbulence on the surface pressure field of a square prism. Journal of Fluid Mechanics, 69, 263–282, 1975.
12. M. M. Alam and Y. Zhou, Flow around two side-by-side closely spaced circular cylinders. Journal of Fluids and Structures, 23, 799–805, 2007. https://doi.org/10.1016/j.jfluidstructs.2006.12.002.
13. M. M. Alam and Y. Zhou, Intrinsic features of flow around two side-by-side square cylinders. Physics of Fluids, 25, 085106, 2013. https://doi.org/10.1063/1.4817670.
14. S. C. Yen and J. H. Liu, Wake flow behind two side-by-side square cylinders. International Journal of Heat and Fluid Flow, 32, 41–51, 2011. https://doi.org/http://dx.doi.org/10.1016/j.ijheatfluidflow.2010.09.005.
15. D. Chatterjee and S. Amiroudine, Two-dimensional mixed convection heat transfer from confined tandem square cylinders in cross-flow at low Reynolds numbers. International Communications in Heat and Mass Transfer, 37, 7–16, 2010. https://doi.org/10.1016/j.icheatmasstransfer.2009.10.007.
16. T. Zheng, S. K. Tang, B. Fei, C. Kung, T.-T. Liao, K.-H. Tseng, K.-Y. Chen, M.-S. Chuang, K. Zarei and A. Y. Goharrizi, On the forces and strouhal numbers in the low reynolds number wakes of two cylinders in tandem. Transactions of the Canadian Society for Mechanical Engineering, 33 349 (2009). https://doi.org/10.1139/tcsme-2009-0025.
17. A. Sohankar and A. Etminan, Forced‐convection heat transfer from tandem square cylinders in cross flow at low Reynolds numbers. International Journal for Numerical Methods in Fluids, 60, 733–751, 2009. https://doi.org/10.1002/fld.1909.
18. J. C. Hu and Y. Zhou, Flow structure behind two staggered circular cylinders. Part 1. Downstream evolution and classification. Journal of Fluid Mechanics, 607, 51–80, 2008. https://doi.org/10.1017/S0022112008001808.
19. J. C. Hu and Y. Zhou, Flow structure behind two staggered circular cylinders. Part 2. Heat and momentum transport. Journal of Fluid Mechanics, 607, 81–107, 2008. https://doi.org/ 10.1017/S0022112008001808.
20. M. M. Alam and H. Sakamoto, Investigation of Strouhal frequencies of two staggered bluff bodies and detection of multistable flow by wavelets. Journal of Fluids and Structures, 20, 425–449, 2005. https://doi.org/10.1016/j.jfluidstructs.2004.11.003.
21. Y. Zhou, S. X. Feng, M. M. Alam, and H. L. Bai, Reynolds number effect on the wake of two staggered cylinders. Physics of Fluids, 21, 125105, 2009. https://doi.org/10.1063/1.3275846.
22. B. A. Fleck, Strouhal numbers for flow past a combined circular-rectangular prism. Journal of Wind Engineering and Industrial Aerodynamics, 89, 751–755, 2001. https://doi.org/10.1016/S0167-6105(00)00087-8.
23. T. Yavuz, Y. E. Akansu, M. SARIOĞLU and M. Özmert, Vortex Shedding on Combined Bodies at Incidence to a Uniform Air Stream. Proceedıngs of World Academy of Science Engineering and Technology, 41, 1095–1099, 2009.
24. P. W. Bearman and A. J. Wadcock, The interaction between a pair of circular cylinders normal to a stream. Journal of Fluid Mechanics, 61 499 (1973). https://doi.org/10.1017/S0022112073000832.
25. M. M. Alam and Y. Zhou, Strouhal numbers, forces and flow structures around two tandem cylinders of different diameters. Journal of Fluids and Structures, 24, 505–526, 2008. https://doi.org/10.1016/j.jfluidstructs.2007.10.001.
26. G. Xu and Y. Zhou, Strouhal numbers in the wake of two inline cylinders. Experiments in Fluids, 37, 248–256, 2004. https://doi.org/10.1007/s00348-004-0808-0.
27. M. Sarioglu, Y. E. Akansu and T. Yavuz, Flow around a rotatable square cylinder-plate body. AIAA journal, 44, 1065–1072, 2006. https://doi.org/10.2514/1.18069.
28. C.-Y. Wei and J.R. Chang, Wake and base-bleed flow downstream of bluff bodies with different geometry. Experimental thermal and fluid science, 26, 39–52, 2002. https://doi.org/10.1016/S0894-1777(02)00111-5