Studi Numerik Pengaruh Preset Angle of Attack Fixed Pitch Blade terhadap Performansi Turbin Hidrokinetik Dual Stage Cascaded

Dermawan, Ahmadi Dzikri (2026) Studi Numerik Pengaruh Preset Angle of Attack Fixed Pitch Blade terhadap Performansi Turbin Hidrokinetik Dual Stage Cascaded. Other thesis, Institut Teknologi Sepuluh Nopember.

Text 5009221132-Undergraduate_Thesis.pdf - Accepted Version Restricted to Repository staff only Download (8MB) | Request a copy

Abstract

Penelitian ini bertujuan untuk menganalisis pengaruh variasi preset angle of attack (AoA) terhadap performa turbin hidrokinetik Darrieus dual-stage cascaded berbilah NACA 0018 pada kondisi arus rendah hingga menengah (0,5–2,5 m/s). Tujuh konfigurasi preset AoA dievaluasi, yaitu A1 (0°,0°,0°) hingga A7 (7°,7°,7°), dengan kombinasi sudut 0°, 5°, dan 7° pada posisi radial bilah R, 0,7R, dan 0,5R. Metode penelitian dilakukan melalui simulasi Computational Fluid Dynamics (CFD) transient dua dan tiga dimensi menggunakan model turbulensi SST k-ω, yang telah diverifikasi melalui Grid Independence Test dan divalidasi terhadap data eksperimen Sheldahl & Klimas (1981) dengan selisih di bawah 10%. Parameter yang dianalisis meliputi karakteristik self-starting, RPM steady-state, gaya lift dan drag, distribusi torsi pada empat kuadran azimuth, tingkat fluktuasi torsi (fluctuation rate), koefisien daya (Cp), koefisien torsi (Ct), tip speed ratio (TSR), serta fenomena aliran lokal berupa kontur kecepatan, kontur tekanan, dan interaksi wake antarbilah. Hasil penelitian menunjukkan bahwa variasi preset AoA memberikan pengaruh signifikan terhadap seluruh parameter performa turbin. Konfigurasi A2 (0°,0°,5°) menghasilkan keseimbangan performa terbaik dengan durasi self-start tercepat (±2 detik) dan skor gabungan performa tertinggi, sedangkan konfigurasi A3 (0°,5°,5°) mencatatkan koefisien daya (Cp) maksimum sebesar 37,50% pada kecepatan aliran 1 m/s, melampaui capaian penelitian preset AoA terdahulu pada bilah tunggal (34,80%) maupun modifikasi geometri bilah lainnya. Analisis fenomena aliran lokal mengonfirmasi bahwa preset AoA 5° menghasilkan flow attachment yang lebih stabil, wake yang lebih sempit, dan distribusi tekanan yang lebih merata dibandingkan preset AoA 7° yang memicu separasi aliran dini dan fluktuasi torsi lebih besar akibat interaksi wake antarbilah dan antar-stage. Hasil ini membuktikan bahwa penerapan preset AoA yang tepat pada konfigurasi multi-bilah cascaded mampu meningkatkan kemampuan ekstraksi energi turbin hidrokinetik dual-stage cascaded secara pasif pada kondisi arus rendah hingga menengah, tanpa memerlukan sistem kontrol mekanik tambahan seperti variable pitch.
=====================================================================================================================================
This study aims to analyze the effect of preset angle of attack (AoA) variations on the performance of a dual-stage cascaded Darrieus hydrokinetic turbine with NACA 0018 blades under low-to-medium flow conditions (0.5–2.5 m/s). Seven preset AoA configurations were evaluated, ranging from A1 (0°,0°,0°) to A7 (7°,7°,7°), combining angles of 0°, 5°, and 7° at blade radial positions of R, 0.7R, and 0.5R. The study was conducted through transient two- and three-dimensional Computational Fluid Dynamics (CFD) simulations using the SST k-ω turbulence model, verified through a Grid Independence Test and validated against the experimental data of Sheldahl & Klimas (1981) with a deviation below 10%. The parameters analyzed include self-starting characteristics, steady state RPM, lift and drag forces, torque distribution across four azimuthal quadrants, torque fluctuation rate, power coefficient (Cp), torque coefficient (Ct), tip speed ratio (TSR), and local flow phenomena such as velocity contours, pressure contours, and inter-blade wake interaction. The results show that preset AoA variation significantly affects all turbine performance parameters. Configuration A2 (0°,0°,5°) achieved the best overall performance balance, with the fastest self-start duration (±2 seconds) and the highest composite performance score, while configuration A3 (0°,5°,5°) recorded a maximum power coefficient (Cp) of 37.50% at a flow velocity of 1 m/s, surpassing previous preset AoA studies on single blades (34.80%) as well as other blade geometry modifications. Local flow analysis confirmed that a 5° preset AoA produced more stable flow attachment, a narrower wake, and a more uniform pressure distribution compared to a 7° preset, which induced earlier flow separation and greater torque fluctuation due to inter-blade and inter-stage wake interaction. These findings demonstrate that properly applied preset AoA in a cascaded multi-blade configuration can passively enhance the energy extraction capability of dual-stage cascaded hydrokinetic turbines under low-to-medium flow conditions, without requiring additional mechanical control systems such as variable pitch.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Turbin hidrokinetik, dual-stage cascaded, preset angle of attack, coefficient of power, Computational Fluid Dynamics, Hydrokinetic turbine, dual-stage cascaded, preset angle of attack, power coefficient, Computational Fluid Dynamics
Subjects:	T Technology > TA Engineering (General). Civil engineering (General) > TA357 Computational fluid dynamics. Fluid Mechanics V Naval Science > VM Naval architecture. Shipbuilding. Marine engineering > VM740 Marine turbines
Divisions:	Faculty of Industrial Technology and Systems Engineering (INDSYS) > Physics Engineering > 30201-(S1) Undergraduate Thesis
Depositing User:	Ahmadi Dzikri Dermawan
Date Deposited:	04 Aug 2026 02:43
Last Modified:	04 Aug 2026 02:43
URI:	http://repository.its.ac.id/id/eprint/142468

Actions (login required)

View Item