PENGARUH TANDEM-STAGGER CYLINDER TERHADAP PERFORMA AERODINAMIKA TURBIN ANGIN SAVONIUS

Turbin angin Savonius merupakan salah satu jenis turbin angin sumbu vertikal yang memiliki kemampuan self-starting yang baik dan mampu beroperasi pada kecepatan angin rendah. Namun, performa aerodinamikanya masih relatif rendah akibat tingginya gaya hambat pada returning blade. Penelitian ini bertujuan untuk menganalisis pengaruh pemasangan tandem-stagger cylinder terhadap performa aerodinamika turbin Savonius melalui variasi spacing ratio (S/D) sebesar 0,8; 0,9; 1,0; dan 1,1. Metode yang digunakan adalah simulasi numerik berbasis Computational Fluid Dynamics (CFD) menggunakan pendekatan Unsteady Reynolds Averaged Navier-Stokes (URANS) dengan model turbulensi SST k-ω. Simulasi dilakukan pada kecepatan angin 5 m/s dengan bilangan Reynolds Number 1.2 x 105. Parameter yang dianalisis meliputi coefficient of power (Cp), coefficient of moment (Cm), distribusi tekanan, distribusi kecepatan, vorticity magnitude, dan turbulence intensity. Hasil penelitian menunjukkan bahwa konfigurasi tandem-stagger cylinder mampu meningkatkan performa turbin dibandingkan rotor konvensional. Konfigurasi terbaik diperoleh pada S/D = 0,8 dengan nilai Cp maksimum sebesar 0,354 dan Cm maksimum sebesar 0,590. Dibandingkan rotor konvensional yang memiliki Cp maksimum sebesar 0,221, terjadi peningkatan performa sebesar 60,18%. Peningkatan tersebut disebabkan oleh redistribusi tekanan yang lebih menguntungkan pada advancing blade, berkurangnya efek hambatan pada returning blade, serta terbentuknya pola aliran yang mampu mengendalikan wake dan vorteks di sekitar rotor. Dengan demikian, penerapan tandem-stagger cylinder pada konfigurasi S/D = 0,8 terbukti efektif dalam meningkatkan performa aerodinamika turbin angin Savonius.

The Savonius wind turbine is a type of vertical-axis wind turbine that offers excellent self-starting capability and can operate effectively under low wind speed conditions. However, its aerodynamic performance remains relatively low due to the high drag force acting on the returning blade. This study aims to investigate the effect of a tandem-stagger cylinder on the aerodynamic performance of a Savonius wind turbine by varying the spacing ratio (S/D) of 0.8, 0.9, 1.0, and 1.1. The research employs a numerical simulation approach using Computational Fluid Dynamics (CFD) with the Unsteady Reynolds-Averaged Navier-Stokes (URANS) method and the SST k-ω turbulence model. Simulations were conducted at a wind speed of 5 m/s with a Reynolds number of 1.2 x 105. The analyzed parameters include the coefficient of power (Cp), coefficient of moment (Cm), pressure distribution, velocity distribution, vorticity magnitude, and turbulence intensity. The results indicate that the implementation of a tandem-stagger cylinder significantly improves turbine performance compared to the conventional rotor configuration. The optimum performance was achieved at S/D = 0.8, yielding a maximum Cp of 0.354 and a maximum Cm of 0.590. Compared to the conventional rotor with a maximum Cp of 0.221, the proposed configuration achieved a performance improvement of 60.18%. This enhancement is attributed to a more favorable pressure distribution on the advancing blade, reduced adverse drag on the returning blade, and the formation of a flow structure capable of controlling wake development and vortex formation around the rotor. Therefore, the application of a tandem-stagger cylinder with an S/D ratio of 0.8 is proven to be an effective approach for improving the aerodynamic performance of Savonius wind turbines.