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    Öğe
    Passive Flow Control around NACA 0018 Airfoil Using Riblet at Low Reynolds Number
    (2021) Güler, Emre; Durhasan, Tahir; Karasu, İlyas; Akbıyık, Hürrem
    In this study, aerodynamic capabilities of NACA 0018 airfoil is numerically investigatedby installing riblet on the suction side of airfoil. Numerical results were obtained by ANSYS Fluentusing k-kl-kw transition model at Reynolds number of Re=100 000. Three different riblet airfoilconfiguration was performed at six different angles of attack (?=8°, 10°, 13°, 15°, 17° and 19°) andthese results compared with the clean model. For M1 model the riblet was located at chord wise sectionof x/c=0.3 while it installed at x/c=0.7 for M2 model. For M3 model two riblets were used and theywere located at both x/c=0.3 and x/c=0.7. Obtained numerical result show that the use of ribletremarkably affects the flow characteristics of airfoil. At ?=8° the CL/CD value of M1 model is increasedby 4.5% when compared to clean model. It is indicated that angle of attack at ?=10o , lift coefficient isincreased for all models with compared to clean model. Stall angle is delayed from ?=13° to ?=15° atM1 and M3 with compared to clean model and lift coefficient is increased about 37% because of therestriction of the laminar separation bubble and trailing edge separation.
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    Öğe
    The Effect of Riblets on the Aerodynamic Performance of NACA 0018 Airfoil
    (2024) Güler, Emre; Pınar, Engin; Durhasan, Tahir
    In this numerical study, riblets on the airfoil were utilized to enhance the aerodynamic performance of NACA0018 airfoil. Riblets of identical height and base length are strategically placed on the suction surface of the airfoil with varying spacing ratios along the flow direction (x) and chord length (c), specifically x/c = 0.3 and 0.7. Four distinct riblet airfoil models are subjected to computational fluid dynamics (CFD) analysis within an angle of attack range from 0° to 21° at a Reynolds number of Re=1×105. The obtained results are systematically compared with the performance of the plain airfoil. Numerical analyses reveal the significant influence of the spacing ratio on flow control and the overall aerodynamic performance of the airfoil, establishing a direct relationship with riblet spacing. The presence of riblet structures is observed to increase the lift coefficient, concurrently delaying the stall angle up to 19°. Notably, the ribbed structures effectively mitigate the interaction between the laminar separation bubble and trailing edge separation, leading to a reduction in turbulent kinetic energy values.
  • [ X ]
    Öğe
    The effect of the riblets on flow control of NACA0018 at low reynolds number
    (Adana Alparslan Türkeş Bilim ve Teknoloji Üniversitesi, 2021) Güler, Emre; Durhasan, Tahir
    Son yıllarda, insansız hava araçlarında ve rüzgar türbinlerinde, türbülansa geçişi ve laminer ayrılma kabarcığını kontrol etmek için düşük Reynolds sayılı akışlarda sayısal ve deneysel aerodinamik çalışmalar yoğunlaşmıştır. Bu tez çalışmasında, kaldırma ve kaldırma/sürükleme oranı gibi aerodinamik katsayıları artırmak için Re=1x105 Reynolds sayısında riblet yüzeyi kullanılarak NACA 0018 kanat profili üzerindeki akışın kontrolü için sayısal analiz yapılmıştır. Ribletler kanat profilinin emme yüzeyine yerleştirilmiştir. Riblet yüksekliği, lokasyon, ribletler arası boşluk oranı, riblet bölgesinin büyüklüğü, riblet şekli ve hücum açısı temel parametreler olarak seçilmiştir. Nümerik analizler k-kl-w geçiş modeli kullanılarak yürütülmüştür. Elde edilen sonuçlar riblet yüksekliğinin laminar ayrılma kabarcığı oluşumunu önemli ölçüde etkilediğini ve temel kanat profiline kıyasla kaldırma katsayısını artırdığını göstermektedir.