Putra, Rahma Shidqi Mahdi (2026) Studi Numerik Pengaruh Pemasangan Riblet Segitiga Terhadap Perubahan Karakteristik Aliran Pada Airfoil Simetri Naca 0026 Studi Kasus Riblet Ukuran s = h = 0,5 mm, Orientasi: Longitudinal, Alignment: Indented. Other thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Stall merupakan kondisi ketika pesawat mengalami penurunan gaya angkat akibat terjadinya separasi aliran lebih awal pada sayap, manuver perubahan arah yang terlalu tajam, serta berkurangnya kecepatan terbang. Berbagai metode telah dikembangkan untuk mengurangi risiko stall, salah satunya melalui penerapan riblet sebagai kontrol aliran pasif di sekitar airfoil. Penelitian mengenai pemasangan riblet ini bertujuan untuk menganalisis pengaruh penggunaan riblet terhadap nilai koefisien gaya angkat (lift coefficient) dan koefisien gaya hambat (drag coefficient) dengan membandingkan performa airfoil polos dan airfoil yang dilengkapi riblet. Metode yang digunakan dalam penelitian ini adalah simulasi numerik Computational Fluid Dynamics (CFD) dengan bantuan perangkat lunak ANSYS Fluent untuk menganalisis aliran tiga dimensi. Variasi parameter penelitian meliputi kecepatan aliran bebas sebesar 8, 12, dan 16 m/s serta sudut serang atau angle of attack (α) sebesar -15°, -10°, -5°, 0°, 5°, 10°, dan 15°. Riblet yang diterapkan berbentuk segitiga dengan dimensi alas (s) 0,5 mm dan tinggi (h) 0,5 mm. Riblet dipasang pada posisi 25–30% panjang chord airfoil NACA 0026 yang memiliki panjang chord 200 mm dengan orientasi longitudinal indented. Penelitian ini diharapkan mampu menghasilkan perbandingan nilai koefisien drag (Cd), koefisien lift (Cl), lift-to-drag ratio (Cl/Cd), kontur dan profil kecepatan, serta Turbulent Kinetic Energy (TKE) antara airfoil riblet dan airfoil polos. Hasil penelitian menunjukkan bahwa rasio efisiensi aerodinamika maksimum (Cl/Cd) diperoleh pada sudut serang 7,5°. Secara umum, airfoil polos memperlihatkan kinerja aerodinamika yang lebih unggul dibandingkan airfoil yang dilengkapi riblet. Efektivitas riblet hanya tampak pada kecepatan aliran 8 m/s dengan sudut serang rendah (0° dan ±10°), yang ditandai oleh penurunan koefisien drag (Cd), meningkatnya koefisien lift (Cl), berkurangnya luas daerah berkecepatan rendah di sekitar trailing edge, serta menurunnya nilai Turbulent Kinetic Energy (TKE). Namun, pada kecepatan 12 m/s dan 16 m/s serta sudut serang yang lebih tinggi hingga (±15°), kinerja riblet mengalami penurunan. Pada kondisi tersebut, separasi aliran terjadi lebih cepat, meningkatkan intensitas turbulensi, serta menghasilkan daerah wake yang lebih luas dibandingkan dengan airfoil polos.
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Stall is a condition in which an aircraft experiences a loss of lift due to the early onset of flow separation over the wing, excessively sharp maneuvering, and a reduction in flight speed. Various methods have been developed to mitigate the risk of stall, one of which is the application of riblets as a passive flow control technique around an airfoil. This study aims to investigate the effect of riblet installation on the lift coefficient (Cl) and drag coefficient (Cd) by comparing the aerodynamic performance of a smooth airfoil with that of a riblet-equipped airfoil. The research employed a numerical Computational Fluid Dynamics (CFD) simulation using ANSYS Fluent to analyze three-dimensional flow characteristics. The simulation parameters included free-stream velocities of 8, 12, and 16 m/s and angles of attack (α) of -15°, -10°, -5°, 0°, 5°, 10°, and 15°. The riblets had a triangular geometry with a spacing (s) of 0.5 mm and a height (h) of 0.5 mm. They were installed at 25–30% of the chord length on a NACA 0026 airfoil with a chord length of 200 mm, using a longitudinal indented orientation. This study was conducted to compare the drag coefficient (Cd), lift coefficient (Cl), lift-to-drag ratio (Cl/Cd), velocity contours and profiles, and Turbulent Kinetic Energy (TKE) between the riblet-equipped airfoil and the smooth airfoil. The results indicate that the maximum aerodynamic efficiency (Cl/Cd) was achieved at an angle of attack of 7.5°. In general, the smooth airfoil exhibited superior aerodynamic performance compared with the riblet-equipped airfoil. The beneficial effects of the riblets were observed only at a free-stream velocity of 8 m/s and low angles of attack (0° and ±10°), as indicated by a reduction in the drag coefficient (Cd), an increase in the lift coefficient (Cl), a narrower low-velocity region near the trailing edge, and lower Turbulent Kinetic Energy (TKE). However, at higher free-stream velocities of 12 and 16 m/s and larger angles of attack (±15°), the effectiveness of the riblets decreased. Under these conditions, flow separation occurred earlier, the turbulence intensity increased, and a larger wake region was formed compared with the smooth airfoil.
| Item Type: | Thesis (Other) |
|---|---|
| Uncontrolled Keywords: | NACA 0026, Drag Coefficient, Koefisien Gaya Angkat, Riblet Segitiga, CFD |
| Subjects: | T Technology > TA Engineering (General). Civil engineering (General) > TA357 Computational fluid dynamics. Fluid Mechanics |
| Divisions: | Faculty of Industrial Technology > Mechanical Engineering > 21201-(S1) Undergraduate Thesis |
| Depositing User: | Rahma Shidqi Mahdi Putra |
| Date Deposited: | 04 Aug 2026 03:45 |
| Last Modified: | 04 Aug 2026 03:45 |
| URI: | http://repository.its.ac.id/id/eprint/142924 |
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