İbrahim Halil GÜZELBEY, Yüksel ERASLAN, Mehmet Hanifi DOĞRU

Numerical Investigation of Different Airfoils at Low Reynolds Number in terms of Aerodynamic Performance of Sailplanes by using XFLR5

Kanat tasarımı, tüm hava araçları için olduğu gibi, planörler için de aerodinamik performans açısından kritik öneme sahiptir. Aerodinamik olarak verimli bir planör kanadı tasarımının en önemli aşamalarından biri de uygun kanat kesit geometrisi (kanat profili) seçimidir. Bir kanat tasarımının kanat kesit geometrisi seçimi, öncelikle belirlenen gerekliliklere dayanarak karşılaştırmak üzere, farklı kanat kesit geometrilerinin aerodinamik performans analizlerini gerektirir. Bu çalışmada, dokuz farklı kanat kesit geometrisi planör aerodinamik performansı açısından karşılaştırmak üzere genel kamu lisanslı XFLR5 programı kullanılarak nümerik olarak incelenmiştir. Öncelikle karşılaştırılacak geometriler Eppler, Goettingen, NACA ve Wortmann kanat kesit geometrisi ailelerinden seçilmiştir. Karşılaştırma için programın deneysel verilerle iki boyutlu doğrulaması yapılmış ve seçilen kanat kesit geometrileri aynı koşullar altında analiz edilmiştir. Analizler 2x105 Reynolds sayısında ve -5 ile 20 derece arasındaki hücum açılarında gerçekleştirilmiştir. Analizlerden elde edilen sonuçlara göre kanat kesit geometrileri belirlenen gereklilikler olan kalınlık, maksimum kaldırma katsayısı ve hücum açısı, maksimum kaldırma durumundaki sürüklenme katsayısı, maksimum süzülme oranı, sıfır kaldırma durumundaki yunuslama momenti ve güç faktörüne göre karşılaştırılmıştır.

Anahtar Kelimeler:

Planör, Kanat tasarımı, Kanat kesit geometrisi, XFLR5, Aerodinamik performans

Numerical Investigation of Different Airfoils at Low Reynolds Number in terms of Aerodynamic Performance of Sailplanes by using XFLR5

Wing design has a critical importance for sailplanes as well as for all the aircrafts in terms of aerodynamic performance. One of the important design phases of an aerodynamically efficient sailplane wing is selection of the appropriate airfoil. Airfoil selection of a wing design firstly requires performing aerodynamic performance analyses of different airfoils to compare according to determined requirements. In this study, numerical investigation of nine different airfoils was performed with the aim of comparison in terms of aerodynamic performance of sailplanes by using the general public licensed computer program XFLR5. Firstly, the airfoils which will be compared were selected from Eppler, Goettingen, NACA and Wortmann airfoil families. For the comparison of the airfoils, the two-dimensional analysis validation of the program was done with experimental data, and the airfoils were analyzed in two dimensions under the same validated analysis conditions. The analyses were performed at 2x105 Reynolds number and angle of attacks from -5 to 20 degrees. According to obtained results from the analyses, the airfoils were compared in terms of determined criteria which are thickness, maximum lift coefficient and its angle of attack, maximum drag to lift ratio, drag coefficient at maximum lift condition, pitching moment at zero lift condition and power factor.

Keywords:

Sailplane, Wing design, Airfoil, XFLR5, Aerodynamic performance,

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Deperrois, A. (2009). XFLR5 Analysis of foils and wings operating at low Reynolds numbers. Guidelines for XFLR5.
Drela, M. (1989). XFOIL: An analysis and design system for low Reynolds number airfoils. In Low Reynolds number aerodynamics (pp. 1-12). Springer, Berlin, Heidelberg.
Eppler, R., Somers, D. M. (1980). A computer program for the design and analysis of low-speed airfoils.
Thomas, F., Milgram, J. (1999). Fundamentals of sailplane design (Vol. 3). College Park, Maryland: College Park Press.
Gudmundsson, S. (2013). General aviation aircraft design: Applied Methods and Procedures. Butterworth-Heinemann.
Hansman, R. J., Craig, A. P. (1987). Low Reynolds number tests of NACA 64-210, NACA 0012, and Wortmann FX67-K170 airfoils in rain. Journal of Aircraft, 24(8), 559-566.
Hasan, M., El-Shahat, A., Rahman, M. (2017). Performance Investigation of Three Combined Airfoils Bladed Small Scale Horizontal Axis wind Turbine by BEM and CFD Analysis. Journal of Power and Energy Engineering, 5(05), 14.
Lasauskas, E., Naujokaitis, L. (2009). Analysis of three wing sections. Aviation, 13(1), 3-10.
McGhee, R. J., Walker, B. S., and Millard, B. F. (1988). Experimental Results for Eppler E 387 Airfoil at Low Reynolds Numbers in the Langley Low-Turbulence Pressure Tunnel. NASA Technical Memorandum-4062.
Morgado, J., Vizinho, R., Silvestre, M. A. R., Páscoa, J. C. (2016). XFOIL vs CFD performance predictions for high lift low Reynolds number airfoils. Aerospace Science and Technology, 52, 207-214.
Frati, S. (1946). The Glider. Editore Ulrico Hoepli Milano, Milan, Italy.
Sudhakar, S., Mishra, S., Ramesh, G., Madhavan, K. T., Ahmed, S. (2011). Experimental Studies on SM4308 Airfoil at Low Reynolds Numbers.
Vuruşkan, A., Özdemir, U., Yükselen, M.A., İnalhan, G. (2014, September). Dikey İniş Kalkış Yapabilen Bir İnsansız Hava Aracının (Turaç*) Aerodinamik Analizi. V. ULUSAL HAVACILIK VE UZAY KONFERANSI. Kayseri: Erciyes University.
Wahidi, R., Bridges, D. (2009, June). Experimental investigation of the boundary layer and pressure measurements on airfoils with laminar separation bubbles. In 39th AIAA Fluid Dynamics Conference (p. 4278).
Xin, H. U. A., Rui, G. U., JIN, J. F., LIU, Y. R., Yi, M. A., Qian, C. O. N. G., ZHENG, Y. (2010). Numerical simulation and aerodynamic performance comparison between seagull aerofoil and NACA 4412 aerofoil under low-reynolds. Advances in Natural Science, 3(2), 244-250.
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