Rabbani, Muhammad Pasha Dzaki (2026) Studi Numerik Pengaruh Pemasangan Riblet Terhadap Perubahan Karakteristik Aliran Pada Airfoil Simetri NACA 0026 "Studi Kasus: Riblet Ukuran s = h = 0,5 mm, Orientasi: Transversal, Alignment: Protruded. Other thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Peningkatan efisiensi aerodinamika merupakan salah satu upaya yang terus dikembangkan untuk mengoptimalkan performa airfoil, khususnya melalui pengendalian karakteristik aliran di sekitar permukaan. Salah satu metode yang banyak diteliti adalah penerapan riblet, yaitu struktur mikro yang berfungsi memodifikasi aliran dekat dinding (near-wall flow) sehingga diharapkan mampu mengurangi gaya hambat dan meningkatkan performa aerodinamika. Penelitian ini bertujuan menganalisis pengaruh pemasangan riblet segitiga protruded dengan dimensi s = h = 0,5 mm yang ditempatkan pada 25–40% panjang chord permukaan atas airfoil NACA 0026. Analisis dilakukan secara numerik menggunakan Computational Fluid Dynamics (CFD) dua dimensi pada perangkat lunak ANSYS Fluent dengan model turbulensi Transition SST yang telah divalidasi menggunakan XFOIL. Simulasi dilakukan pada variasi kecepatan aliran bebas 8, 12, dan 16 m/s serta sudut serang (AoA) −15° hingga 15°. Parameter yang dievaluasi meliputi koefisien drag (Cd), koefisien lift (Cl), rasio Cl/Cd, distribusi koefisien tekanan (Cp), kontur dan vektor kecepatan, serta Turbulent Kinetic Energy (TKE). Hasil penelitian menunjukkan bahwa nilai Cd terendah diperoleh pada AoA 0°, sedangkan peningkatan sudut serang menyebabkan nilai Cd semakin besar. Nilai Cl meningkat hampir linier hingga AoA 10°, kemudian menurun pada AoA 15° sebagai indikasi awal terjadinya stall. Rasio Cl/Cd mencapai nilai maksimum pada AoA 10°, namun secara umum airfoil polos masih memiliki efisiensi aerodinamika yang lebih baik dibandingkan airfoil dengan riblet. Analisis distribusi Cp, kontur kecepatan, dan vektor aliran menunjukkan bahwa keberadaan riblet hanya memberikan perubahan lokal pada daerah pemasangannya dan belum mampu mengubah pola aliran global maupun menunda separasi secara signifikan. Di sisi lain, hasil analisis TKE memperlihatkan bahwa pada AoA 10° dan 15° nilai energi kinetik turbulen di daerah 25–40% chord lebih rendah dibandingkan airfoil polos, yang mengindikasikan bahwa riblet mampu mengurangi intensitas turbulensi di sekitar permukaan. Meskipun demikian, penurunan TKE tersebut belum diikuti oleh peningkatan performa aerodinamika secara keseluruhan.
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Improving aerodynamic efficiency by reducing drag without significantly compromising lift has become an important objective in aerodynamic design, as excessive drag increases energy consumption and decreases the lift-to-drag ratio. This study numerically investigates the effects of protruded triangular riblets (S = H = 0.5 mm) installed on the upper surface of a NACA 0026 airfoil over the 25–40% chord length using two-dimensional Computational Fluid Dynamics (CFD) simulations in ANSYS Fluent. Simulations were performed at free-stream velocities of 8, 12, and 16 m/s with angles of attack ranging from −15° to 15°. The Transition SST turbulence model was selected based on validation against XFOIL, which demonstrated good agreement with the pressure coefficient distribution. The aerodynamic parameters evaluated in this study include the drag coefficient (Cd), lift coefficient (Cl), lift-to-drag ratio (Cl/Cd), pressure coefficient (Cp) distribution, velocity contours and vectors, and Turbulent Kinetic Energy (TKE). The results indicate that the minimum Cd occurs at approximately 0° angle of attack and increases with increasing angle of attack, while the riblet configuration does not consistently reduce drag over the investigated operating conditions. The Cl increases almost linearly up to approximately 10°, followed by a decrease at 15°, indicating the onset of stall. The maximum aerodynamic efficiency (Cl/Cd) is achieved at 10°, although the smooth airfoil generally exhibits higher efficiency than the riblet-equipped configuration. Furthermore, the Cp distribution and the overall flow field remain relatively similar for both configurations, suggesting that the influence of the riblets is primarily confined to the near-wall region without significantly delaying flow separation. However, the TKE analysis reveals that at 10° and 15° angles of attack, the riblet configuration produces lower turbulent kinetic energy within the 25–40% chord region compared with the smooth airfoil, indicating its capability to suppress local turbulence intensity. Nevertheless, this reduction in TKE does not result in a measurable improvement in the overall aerodynamic performance of the airfoil.
| Item Type: | Thesis (Other) |
|---|---|
| Uncontrolled Keywords: | Riblet, NACA 0026, CFD, Koefisien Drag, Koefisien Lift |
| Subjects: | T Technology > T Technology (General) T Technology > T Technology (General) > T57.62 Simulation T Technology > TA Engineering (General). Civil engineering (General) T Technology > TA Engineering (General). Civil engineering (General) > TA357 Computational fluid dynamics. Fluid Mechanics T Technology > TJ Mechanical engineering and machinery T Technology > TL Motor vehicles. Aeronautics. Astronautics T Technology > TL Motor vehicles. Aeronautics. Astronautics > TL521 Aerodynamics, Hypersonic. |
| Divisions: | Faculty of Industrial Technology > Mechanical Engineering |
| Depositing User: | Muhammad Pasha Dzaki Rabbani |
| Date Deposited: | 31 Jul 2026 01:13 |
| Last Modified: | 31 Jul 2026 01:13 |
| URI: | http://repository.its.ac.id/id/eprint/140126 |
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