https://dx.doi.org/10.20961/mekanika.v20i1.47577 Revised 17 March 2021; received in revised version 20 March 2021; Accepted 21 March 2021 Available Online 31 March 2021 2579-3144 © 2021 Mekanika: Majalah Ilmiah Mekanika. All right reserved 9 Mekanika: Majalah Ilmiah Mekanika Volume 20 (1) 2021 Page 9 - 17 Initial Rotation Characteristic Investigation of a Hybrid Savonius - Darrieus Wind Turbine using 6 DOF Computational Fluid Dynamics Hangga Wicaksono 1* , Sugeng Hadi Susilo 1 , Bayu Pranoto 1 , Muhammad Fakhruddin 1 1 Department of Mechanical Engineering, State Polytechnic of Malang, Soekarno Hatta 09, Malang, Indonesia *wicaksonohangga@polinema.ac.id Keywords: Vertical Axis Wind Turbine, 6DOF Computational Fluid Dynamics The inconsistency of the wind flow considered as one of the factors which tend to decrease the performance of the wind turbine. This paper proposes a further analysis of the initial rotation characteristic of a hybrid Savonius - Darrieus wind turbine. The addition of the Darrieus blade intends to increase the aerodynamic stability of the overlapping Savonius turbine. This study implements 2D CFD transient analysis using the 6DOF methods in 0 0 , 30 0 , 60 0 , and 90 0 Darrieus blade position along with 2 m/s, 4 m/s, and 6 m/s wind speed variations. The results of the aerodynamic analysis show that the location of the Darrieus 30 0 turbine provides the greatest initial repulsion, especially when the turbine rotation is above 90 0 , the position of the Darrieus blade can provide additional impulse force when the Savonius turbine tends to be passive. This effect occurs more significant at higher wind speeds. Savonius with 3-blade modification has a more stable level of force distribution than the 2-blade modification, although the value is smaller. This shows that the 3-blade Savonius provide a higher stability of angular velocity development. ) 1 Introduction Savonius wind turbine is simple but effective to be applied in a relatively low wind speed and inconstant direction. The performance of Savonius type wind turbines decreases in relatively high wind speed. This is caused by the presence of turbulence in the airflow shortly after passing the blades on Savonius wind turbines [1]. The highest average efficiency in Savonius turbines is 16% [2]. This value is so small that certain innovations are needed to improve turbine efficiency. The presence of wind collisions in the inactive blades results in obstacles to the turbine rotation. The effect of the number of blades on conventional Savonius turbines shows that turbines with a number of 2 blades have a slightly higher rotor rotation value than turbines with 3 blades [3]. Another study shows that using 4 Savonius turbine blades has an efficiency value of up to 10%. The efficiency value is also greatly influenced by the ratio of the gearbox used. [4] The selection of Darrieus blade types using the NACA 2412 model has a maximum generated power of 16.38 W at a wind speed of 6 m/s and the number of turbine blades of 4 units. However, the minimum