Studi Numerik Performa Aerodinamis Turbin Angin Contra-Rotating Sumbu Horizontal Menggunakan Metode 6DOF Dynamic Mesh dan Moving Reference Frame

Rizqi Raihan, Dr.-Ing. Ir. Ryan Anugrah Putra, S.T., M.Sc., M.Eng.

2026 | Skripsi | TEKNIK MESIN

Indonesia memiliki potensi energi angin berkecepatan rendah hingga sedang (3–5 m/det), seperti di salah satu kawasan pembangkitan listrik di Jawa Tengah. Kondisi ini kurang ideal bagi turbin angin rotor tunggal (SRWT) konvensional yang umumnya optimal pada kecepatan di atas 7 m/det. Sebagai solusi, sistem Contra Rotating Wind Turbine (CRWT) diusulkan karena mampu melampaui batas Betz dengan mengekstraksi sisa energi kinetik dari wake rotor depan. Penelitian ini bertujuan merancang geometri CRWT dan membandingkan performa tiga konfigurasinya secara numerik pada variasi kecepatan angin 3, 6, dan 9 m/det.

Rotor depan dirancang menggunakan metode Blade Element Momentum (BEM) dengan airfoil SG6043 untuk kecepatan desain 6 m/det. Geometri rotor belakang disesuaikan dengan kecepatan wake efektif (4 m/det) dari hasil simulasi transient pada konfigurasi simetris. Tiga variasi yang diuji meliputi CRWT 1 (simetris), CRWT 2 (rotor kecil di depan, besar di belakang), dan CRWT 3 (rotor besar di depan, kecil di belakang). Simulasi dilakukan dengan dua pendekatan: transient dan MRF untuk mengekstraksi torsi dan daya. 

Hasil komputasi menunjukkan bahwa CRWT 3 konsisten menghasilkan daya mekanik tertinggi pada seluruh kecepatan uji, yakni 172,61 W (3 m/det), 1416,34 W (6 m/det), dan 4809,21 W (9 m/det). Hasil ini mengungguli CRWT 2 dengan selisih 36,8–52,4% serta mendominasi CRWT 1 secara signifikan. Disimpulkan bahwa penempatan rotor besar di posisi depan merupakan strategi desain CRWT yang paling unggul untuk memaksimalkan ekstraksi daya di wilayah berkecepatan angin rendah.

Indonesia possesses low-to-medium wind energy potential (3–5 m/s), particularly in regions such as in the power plant area in Central Java. These conditions are suboptimal for conventional single-rotor wind turbines (SRWTs), which typically operate optimally at wind speeds exceeding 7 m/s. To address this, a Contra-Rotating Wind Turbine (CRWT) system is proposed due to its capability to surpass the Betz limit by extracting residual kinetic energy from the front rotor's wake. This study aims to design the CRWT geometries and numerically compare the aerodynamic performance of three configurations under varying wind speeds of 3, 6, and 9 m/s.

The front rotor was designed using the Blade Element Momentum (BEM) method with an SG6043 airfoil for a design wind speed of 6 m/s. The rear rotor geometry was adapted to the effective wake velocity (4 m/s) derived from the transient simulation of the symmetrical configuration. The three evaluated variations were CRWT 1 (symmetrical), CRWT 2 (small front rotor, large rear rotor), and CRWT 3 (large front rotor, small rear rotor). Numerical simulations were conducted via two approaches: a transient method to determine the natural steady rotational speed, and a steady-state Moving Reference Frame (MRF) method to extract torque and power generation. 

The computational results indicated that CRWT 3 consistently generated the highest total mechanical power across all tested wind speeds, achieving 172,61 W at 3 m/s, 1416,34 W at 6 m/s, and 4809,21 W at 9 m/s. This performance outperformed CRWT 2 by a margin of 36.8–52.4% and significantly dominated the symmetrical CRWT 1. It is concluded that positioning the larger rotor at the front constitutes the most optimal CRWT design strategy for maximizing power extraction in low wind speed regions

Kata Kunci : Energi Terbarukan, Turbin Angin Contra Rotating, Dynamic mesh, moving reference frame, ANSYS