Studi Numerik Pengaruh Jumlah Bilah dan Jarak Cascade terhadap Performansi Vertical Axis Hydrokinetic Turbine Tipe Darrieus Straight Blade

Andaryani, Defani Hari (2025) Studi Numerik Pengaruh Jumlah Bilah dan Jarak Cascade terhadap Performansi Vertical Axis Hydrokinetic Turbine Tipe Darrieus Straight Blade. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Penelitian ini bertujuan untuk mengevaluasi pengaruh variasi jumlah bilah dan jarak cascade terhadap performa serta pola aliran pada Vertical Axis Hydrokinetic Turbine tipe Darrieus straight blade. Penelitian dilakukan secara numerik menggunakan simulasi Computational Fluid Dynamics (CFD) pada rentang kecepatan arus 0.5 hingga 3 m/s. Variasi jumlah bilah yang digunakan terdiri atas 3, 6, dan 9 bilah, sementara variasi jarak bilah berada pada kisaran 0.4R hingga 0.8R dari pusat rotasi. Hasil simulasi menunjukkan bahwa peningkatan jumlah bilah dari 3 menjadi 9 mampu meningkatkan koefisien performansi (C_p) dan torsi turbin secara signifikan. Namun demikian, peningkatan jumlah bilah juga menyebabkan penurunan nilai Tip Speed Ratio (TSR) dan RPM, yang disebabkan oleh meningkatnya nilai solidity serta momen inersia sistem. Dari aspek performa mekanik, penambahan jumlah bilah memperbesar luas sapuan terhadap aliran air, sehingga berkontribusi pada peningkatan gaya angkat dan torsi. Capaian torsi dan C_p tertinggi diperoleh pada konfigurasi 9 bilah variasi 9B V9, yakni nilai C_p sebesar 0.43 dengan TSR 4.42. Variasi jarak bilah menunjukkan bahwa konfigurasi optimal berada pada kisaran 0.5R–0.7R, yang menghasilkan distribusi aliran lebih teratur, pemulihan wake (wake recovery) yang cepat, serta meminimalkan interferensi antar bilah. Jarak cascade yang lebih dekat ke poros turbin cenderung lebih unggul dalam mendukung kemampuan self-start, sedangkan jarak yang lebih jauh memberikan kontribusi terhadap peningkatan performansi keseluruhan. Untuk konfigurasi 6 bilah, variasi optimal diperoleh pada 6B V5 (0.7R dan R), sedangkan untuk konfigurasi 9 bilah, hasil terbaik dicapai oleh variasi 9B V9 (0.5R; 0.7R; dan R). Visualisasi streamline dan kontur kecepatan mendukung temuan ini, di mana konfigurasi optimal memperlihatkan aliran masuk yang lebih bersih serta zona turbulensi yang lebih kecil di belakang bilah. Oleh karena itu, kombinasi antara jumlah bilah yang tinggi dan jarak cascade yang optimal dapat secara signifikan meningkatkan performansi turbin, baik dari segi efisiensi energi maupun kestabilan mekanis sistem.
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This research aims to evaluate the influence of varying blade numbers and cascade distances on the performance and flow patterns of a straight-bladed Darrieus Vertical Axis Hydrokinetic Turbine. The study was conducted numerically using Computational Fluid Dynamics (CFD) simulations over a current velocity range of 0.5 to 3 m/s. The variations in blade numbers included 3, 6, and 9 blades, while blade distance variations ranged from 0.4R to 0.8R from the center of rotation. Simulation results indicate that increasing the number of blades from 3 to 9 significantly improves the coefficient of performance (C_p) and turbine torque. However, an increase in blade number also leads to a decrease in Tip Speed Ratio (TSR) and RPM, which is attributed to increased solidity and system moment of inertia. From a mechanical performance perspective, adding more blades increases the swept area exposed to water flow, contributing to enhanced lift and torque. The highest torque and C_p were achieved with the 9-blade configuration, specifically 9B V9, yielding a C_p of 0.43 with a TSR of 4.42. Blade distance variations show that the optimal configuration lies within the 0.5R–0.7R range, resulting in more regular flow distribution, rapid wake recovery, and minimized blade interference. Cascade distances closer to the turbine axis tend to be superior in supporting self-start capability, while larger distances contribute to overall performance improvement. For the 6-blade configuration, the optimal variation was 6B V5 (0.7R and R), whereas for the 9-blade configuration, the best results were achieved by 9B V9 (0.5R; 0.7R; and R). Streamline visualization and velocity contours support these findings, where optimal configurations demonstrate cleaner incoming flow and smaller turbulence zones behind the blades. Therefore, a combination of a high number of blades and optimal cascade distance can significantly enhance turbine performance, in terms of both energy efficiency and system mechanical stability.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Turbin Hidrokinetik, VAHT Darrieus, Jumlah Bilah, Jarak Cascade, CFD, Performansi, Hydrokinetic Turbine, Darrieus VAHT, Number of Blades, Cascade, CFD, Performance
Subjects:	Q Science > QC Physics > QC151 Fluid dynamics T Technology > T Technology (General) > T57.62 Simulation T Technology > TJ Mechanical engineering and machinery > TJ266 Turbines. Turbomachines (General) T Technology > TJ Mechanical engineering and machinery > TJ808 Renewable energy sources. Energy harvesting. T Technology > TL Motor vehicles. Aeronautics. Astronautics > TL521 Aerodynamics, Hypersonic. T Technology > TL Motor vehicles. Aeronautics. Astronautics > TL574.C3 Cascade
Divisions:	Faculty of Industrial Technology and Systems Engineering (INDSYS) > Physics Engineering > 30201-(S1) Undergraduate Thesis
Depositing User:	Defani Hari Andaryani
Date Deposited:	31 Jul 2025 09:58
Last Modified:	31 Jul 2025 09:58
URI:	http://repository.its.ac.id/id/eprint/124384

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