## 1 Introduction
[24] studied the possibility of improving the performance of the Savonius rotor using an arc curtain to guide the air stream. Two-dimensional CFD analysis and experimental studies were conducted to prove that the proposed concept can lead to an increase in turbine power by up to 50%. [PERSON] et al. presented the study [25] on the Savonius wind turbine aerodynamic performance. Three-dimensional CFD simulation with an optimization procedure was used to verify the operating parameters of the rotors, such as geometry and number of blades, space sizing, presence of a guiding curtain, or wind velocity. [PERSON] et al. [26] investigated a scaled-down model of the Savonius rotor. Both numerical and experimental studies were involved. The authors reported guidance to improve the aerodynamic performance of the turbine. [PERSON] et al. presented a numerical study [27] on the Savonius turbine with deformable blades. Two-dimensional CFD analysis was involved, and a significant improvement in the turbine power coefficient was reported for the use of deformable blades. [PERSON] et al. presented a review study [28] on applications of wind deflectors to improve the performance of various types of VAWTs. Savonius wind turbines with two and three blades and various configurations of H-type turbines were considered. Recent studies on the vertical-axis wind turbine with a carousel rotor were presented in publications [29; 30]. The studies focused on the use of single-coherent and dual-coherent blades. But also, the construction, starting method, and starting torque of the vertical-axis carousel wind rotor were comprehensively described. This paper focuses on the effect of blade motion on rotor torque and power considering the case of self-starting conditions, when the rotor started to operate at a wind speed of \(W=5\) m/s, a rotational speed of \(V_{0}=1.35\) m/s, and a tip speed ratio of \(\lambda=0.27\). The primary objective of this study was to compare the simplified analytical method for estimating the driving torque and turbine power with the numerical results obtained through two-dimensional CFD analysis. The second goal was to highlight the main advantage of the carousel wind rotor, which is its higher starting torque compared to the H-type Darrius rotor. Principle of Operation of the Carousel Wind RotorOne rotational cycle of a rotor with three dual-coherent blades is shown in Figure 1. A single blade rotates around its axis, and at the same time, it rotates around the rotor axis. The blade rotates in the opposite direction from the rotor. The blade's rotation around its axis is forced by mechanical gears. For small rotor diameters, a gear transmission can be used, while for larger diameters, a chain transmission can be applied to reduce gear mass. The gear ratio between gears \(z_{1}\) and \(z_{2}\) is 1:2 to obtain the blade positioning shown in the scheme. The vertical-axis carouser wind rotor uses mainly the force of wind pressure as a driving force. Therefore, the analogy with the H-type rotor can be noticed. Figure 1: (**a**) Diagram of the movement of the carousel rotor blades; (**b**) forces acting on the single blade, where \(V_{0}\)—the rotor peripheral speed [m/s]; \(W\)—wind speed [m/s]; \(\alpha\)—the rotor rotation angle and the blade position relative to the rotor [°]; \(R\)—the rotor radius [m], \(F_{xD}\) and \(F_{yD}\)—load components resulting from the air drag the blade is subjected to during rotor rotation; \(F_{xW}\) and \(F_{yW}\)—wind load components generating on the blade. On the other hand, due to the adjustable reference area of the blades, the carousel rotor achieves high starting torque, similar to the Savonius rotor. The way the blades are guided allows the blade to be positioned perpendicular to the direction of the wind. In this position, its entire surface is pressurized, and a high starting torque is obtained. On the other hand, when the blade moves upwind, it is aligned parallel to the wind direction so that it can move with the smallest air drag.