Investigation of the effect of turbulence models for CFD simulations of dynamic airfoils

Abstract

This study presents a numerical investigation into the aerodynamic behavior of a pitching NACA 0012 airfoil under dynamic conditions. The analysis was carried out using a sliding mesh method in Fluent, incorporating sinusoidal pitching motion with various turbulence models, including SST, SST with intermittency, and Transition SST. The effects of different turbulence models on the aerodynamic performance of the airfoil at various angles of attack (AoA) were studied, focusing on the pressure coefficient (Cp), flow structure, and laminar separation bubble (LSB) formation. Additionally, the results for pitch-up and pitch-down motions were compared to evaluate the hysteresis effects and dynamic flow behaviors. The study found that the SST model exhibited inviscid flow characteristics, while the SST with intermittency and Transition SST models captured the boundary layer behavior more effectively, including the separation and reattachment processes. Significant differences were observed in the Cp distribution and turbulence characteristics, with pitch-down motion resulting in higher Cp values and more complex flow phenomena. The results contribute to the understanding of aerodynamic behavior during dynamic motions, offering insights into the role of turbulence models on airfoil performance.

Keywords

• Pitching airfoil
• turbulence model
• pressure distribution
• sinusoidal motion

Dinamik kanat profilinin CFD simülasyonları için türbülans modellerinin etkisinin incelenmesi

Öz

Bu çalışma, dinamik koşullarda yunuslama hareketi yapan bir NACA 0012 kanat profilinin aerodinamik davranışına ilişkin sayısal bir araştırma sunmaktadır. Analiz, SST, SST- intermittency ve Transition SST dahil olmak üzere çeşitli türbülans modelleriyle sinüzoidal hareketini birleştiren Fluent'te kayan bir ağ yöntemi kullanılarak gerçekleştirilmiştir. Farklı türbülans modellerinin, çeşitli hücum açılarında kanat profilinin aerodinamik performansı üzerindeki etkileri, basınç katsayısı, akış yapısı ve laminer ayrılma kabarcığı oluşumuna odaklanılarak incelenmiştir. Ek olarak, yukarı ve aşağı hareketlerinin sonuçları, histerezis etkilerini ve dinamik akış davranışlarını değerlendirmek için karşılaştırılmıştır. Çalışma, SST modelinin görünmez akış karakteristikleri sergilediğini, SST- intermittency ve Transition SST modellerinin ise ayrılma ve yeniden bağlanma süreçleri dahil olmak üzere sınır tabakası davranışını daha etkili bir şekilde yakaladığını bulmuştur. Cp dağılımında ve türbülans özelliklerinde önemli farklılıklar gözlemlendi, aşağı yunuslama hareketi daha yüksek Cp değerleri ve daha karmaşık akış fenomenleriyle sonuçlandı. Sonuçlar dinamik hareketler sırasında aerodinamik davranışın anlaşılmasına katkıda bulunarak türbülans modellerinin rolü kanat profili performansı üzerindeki etkisi hakkında fikir vermiştir.

Anahtar Kelimeler

• yunuslayan kanat profili
• türbülans modeli
• basınç dağılımı
• sinüzoidal hareket

References

1. [1] Baik, Y. S., Bernal, L. P., Granlund, K., & Ol, M. V. (2012). Unsteady force generation and vortex dynamics of pitching and plunging aerofoils. Journal of Fluid Mechanics, 709, 37-68.
2. [2] Brunton, S., & Rowley, C. (2009, January). Modeling the unsteady aerodynamic forces on small-scale wings. In 47th AIAA aerospace sciences meeting including the new horizons forum and aerospace exposition (p. 1127).
3. [3] Catlett, M. R., Anderson, J. M., Badrya, C., & Baeder, J. D. (2020). Unsteady response of airfoils due to small-scale pitching motion with considerations for foil thickness and wake motion. Journal of Fluids and Structures, 94, 102889.
4. [4] Hue, D., Vermeersch, O., Bailly, D., Brunet, V., & Forte, M. (2015). Experimental and numerical methods for transition and drag predictions of laminar airfoils. AIAA Journal, 53(9), 2694-2712.
5. [5] D'Alessandro, V., Montelpare, S., Ricci, R., & Zoppi, A. (2017). Numerical modeling of the flow over wind turbine airfoils by means of Spalart–Allmaras local correlation based transition model. Energy, 130, 402-419.
6. [6] Amiralaei, M. R., Alighanbari, H., & Hashemi, S. M. (2010). An investigation into the effects of unsteady parameters on the aerodynamics of a low Reynolds number pitching airfoil. Journal of Fluids and Structures, 26(6), 979-993.
7. [7] Arena, A. V., & Mueller, T. J. (1980). Laminar separation, transition, and turbulent reattachment near the leading edge of airfoils. AIAA journal, 18(7), 747-753.
8. [8] Kim, D. H., & Chang, J. W. (2014). Low-Reynolds-number effect on the aerodynamic characteristics of a pitching NACA0012 airfoil. Aerospace Science and Technology, 32(1), 162-168.

9. [9] Lorber, P. F., & Carta, F. O. (1992, January). Unsteady transition measurements on a pitching three-dimensional wing. In California State Univ., The Fifth Symposium on Numerical and Physical Aspects of Aerodynamic Flows.
10. [10] Poirel, D., & Yuan, W. (2010). Aerodynamics of laminar separation flutter at a transitional Reynolds number. Journal of Fluids and Structures, 26(7-8), 1174-1194.
11. [11] Hain, R., Kähler, C. J., & Radespiel, R. (2009). Dynamics of laminar separation bubbles at low-Reynolds-number aerofoils. Journal of Fluid Mechanics, 630, 129-153.
12. [12] Menter, F. R., Langtry, R. B., Likki, S. R., Suzen, Y. B., Huang, P. G., & Völker, S. (2006). A correlation-based transition model using local variables—part I: model formulation. Journal of turbomachinery, 128(3), 413-422.
13. [13] Grille Guerra, A., Hosseinverdi, S., Little, J. C., & Fasel, H. F. (2022). Unsteady behavior of a laminar separation bubble subjected to wing structural motion. In AIAA SciTech 2022 Forum (p. 2331).
14. [14] Lian, Y., Ol, M., & Shyy, W. (2008). Comparative study of pitch-plunge airfoil aerodynamics at transitional reynolds number. In 46th AIAA aerospace sciences meeting and exhibit (p. 652).
15. [15] Chen, Z., Xiao, T., Wang, Y., & Qin, N. (2021). Laminar separation bubble dynamics and its effects on thin airfoil performance during pitching-up motion. Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, 235(16), 2479-2492.
16. [16] Rezaei, A. S., & Taha, H. (2021). Circulation dynamics of small-amplitude pitching airfoil undergoing laminar-to-turbulent transition. Journal of Fluids and Structures, 100, 103177.
17. [17] Özkan R., Genç M.S., Aerodynamic design and optimization of a small-scale wind turbine blade using a novel artificial bee colony algorithm based on blade element momentum (ABC-BEM) theory, Energy Conversion and Management, 283, 116937, 2023.
18. [18] Yapιcι H., Genç M.S., Özιşιk G., Transient temperature and thermal stress distributions in a hollow disk subjected to a moving uniform heat source, Journal of Thermal Stresses, 31 (5), 476-493, 2008.
19. [19] Aktepe B., Demir H., Impact of Window Opening Shapes on Wind-Driven Cross Ventilation Performance in a Generic Isolated Building: A Simulation Study, Gazi University Journal of Science Part C: Design and Technology 12 (3), 758-768, 2024.
20. [20] Demir H., Çimen M., Yılman Ö., Tekin E., Computational Fluid Dynamics Analysis of Drag Reduction in Bullet via Geometric Modifications, Bayburt Üniversitesi Fen Bilimleri Dergisi 7 (1), 47-56, 2024.
21. [21] Genç M.S., Control of low Reynolds number flow over aerofoils and investigation of aerodynamic performance, PhD Thesis, Graduate School of Natural and Applied Sciences, Erciyes University, Kayseri, 2009.
22. [22] Genç M.S., Kaynak Ü., Control of flow separation and transition point over an aerofoil at low Re number using simultaneous blowing and suction, 19th AIAA Computational Fluid Dynamics, AIAA-3672, 2009.
23. [23] Demir H., Kaya B., Investigation of the aerodynamic effects of bio-inspired modifications on airfoil at low Reynolds number, Journal of Mechanical Engineering and Sciences 17 (4), 9715–9724, 2023.