## 4 Conclusions  
In this paper, a comparison was presented between the simplified analytical approach proposed for estimating the driving torque and power of a VAWT turbine with a carousel rotor, and the numerical results obtained using CFD analysis. The study focused on the effect of blade motion on rotor torque and power when the rotor operates at a wind speed of \(W=5\) m/s and a rotational speed of \(V_{0}=1.35\) m/s, and with a tip speed ratio of \(\lambda=0.27\). The tip speed ratio was determined experimentally in the wind tunnel laboratory. Based on the forces \(P_{x}\) and \(P_{y}\) on the blade obtained from sectional model tests described in [30], a simplified analytical approach was proposed, which assumes that the blade is affected simultaneously by the wind load and a drag force tangential to the rotor rotation direction. Considering the above assumptions, a computational algorithm was prepared to determine the values of the forces acting on the blade \(F_{x}\) and \(F_{y}\) depending on the wind speed and rotor speed during its movement. The proposed analytical approach enables the determination of turbine torque and power values for a three-bladed rotor, as demonstrated in the paper. In parallel, CFD numerical analysis was carried out for the same cases and conditions as in the experimental and analytical approaches. Comparing the results obtained from the analytical approach and the CFD-based approach, the error in determining the average driving torque and average turbine power was about 1%. The CFD numerical analysis confirmed the accuracy of the analytical approach's assumptions. In addition, it considered the influence of aerodynamic interference between individual turbine blades and individual blade lobes. This was demonstrated by reported local discrepancies in analytical and numerical results. The paper mainly focused on presenting the problem resulting from the operation of the mechanism and the movement of the blades, without treating the turbine as a rotor \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Analytical Approach** &
\begin{tabular}{c} **CFD** \\ **Simulation** \\ \end{tabular} & **Error** \\ \hline Average torque & 1.26 [Nm] & 1.27 [Nm] & 0.9\% \\ Average power & 5.67 [W] & 5.72 [W] & 0.9\% \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Average torque and power. with high energy potential. Therefore, a turbine of small size was chosen for analysis. The average turbine power was also small. The larger power outputs of the presented design of the VAWT turbine with a carousel rotor can be obtained by appropriate geometry scaling. In this work, a constant wind direction was assumed. In the case of the carousel rotor, this was an important assumption, because the obtained results were presented for the angular position of the blades at which the turbine achieves the highest driving torque. If the direction of the wind changes, the position of the blades must also be changed, which in practice is achieved through a wind direction adjusting mechanism. The problem of adjusting the rotor to the wind direction in order to obtain a constant maximum power will be a further subject of our research. The developed analytical method was used to assess the starting conditions. For a relevant example, it was proved that the torque coefficient for the carousel wind rotor with three dual-coherent blades was more than 13 times higher compared to the torque coefficient obtained for the H-type Darrieus rotor with three NACA0015 airfoils. Accordingly, the main advantage of the carousel wind rotor, which is a good starting performance, was demonstrated. Conceptualization, F.L. and M.A. ; methodology, F.L. and M.A. ; software, F.L. ; validation, M.A. and F.L. ; formal analysis, M.A. ; investigation, M.A. ; data curation, M.A. and F.L. ; writing--original draft preparation, F.L. and M.A. ; writing--review and editing, F.L. and M.A. ; visualization, F.L. and M.A. ; supervision, F.L. All authors have read and agreed to the published version of the manuscript.