## 3 Experimental Results  
Figure 5 shows a curve of the thrust force values depending on the air flow speed.  
The curve shows that the traction force increases with increasing wind speed. This increase is almost linear. At initial wind speeds (3-6 m/s), there is a relatively smooth increase in traction force. Then, at higher speeds (from 6 to 12 m/s), the traction force increases more intensively. These results demonstrate the importance of increasing the  
Figure 4: Closed-flow wind tunnel diagram [29]: 1—working section, 2—ring, 3—diffuser, 4—fan, 5—transition passage, 6, 7, 9, and 10—turning blades, 8—return passage, 11, 13—equalizing grids, 12—prechamber, 14—collector (nozzle).  
Figure 5: Dependence of the thrust force of the wind turbine model on the wind velocity.  
wind speed to improve the performance of a wind turbine since the traction force is directly proportional to the air flow speed, which ultimately affects energy production.  
Also, the values of the number of revolutions of the wind wheel depending on the wind speed were obtained experimentally, as shown in Figure 6.  
As the wind speed increases, a linear increase in the rotor speed is observed. This indicates a direct dependence of the rotor speed on the wind velocity. With a wind velocity of 3 m/s, the rotor rotates at a speed of approximately 25 rpm. With a wind velocity of 12 m/s, the rotor speed reaches approximately 158 rpm. The data show that at low wind speeds (up to 6 m/s), the increase in the number of revolutions is less pronounced, whereas, at wind speeds above 9 m/s, the number of revolutions begins to increase faster, which may indicate an improvement in aerodynamic efficiency at high wind speeds. This curve is helpful in understanding the dynamics of the wind wheel operation with changing wind speeds and can be used to optimize the design of a wind turbine.  
For the selected five wind speed values (3 m/s, 6 m/s, 9 m/s, 12 m/s, and 15 m/s), the starting torque of the wind turbine was measured experimentally. The results are presented in Figure 7.  
In the initial section from 0 to about 9 m/s, the breakaway torque increases almost linearly. This suggests that at lower wind speeds, the torque required to initiate rotation increases uniformly with increasing wind speed. After 9 m/s, the increase in the breakaway torque becomes more pronounced, with a steeper slope. This indicates that the forces acting on the blades begin to increase rapidly, which may be due to a non-linear increase in the aerodynamic forces as the wind speed increases. The maximum breakaway torque at the maximum wind speed (15 m/s) reaches about 4500 N. This shows the maximum value of the torque required to overcome inertia and initiate rotor rotation. The curve is important for understanding the performance of wind turbines at different wind speeds, especially at low speeds, when the moment of inertia is significant. This indicates that as the wind speed increases, the torque required to start the turbine increases significantly, which is important for designing turbines that can start efficiently, even in weak winds.  
Figure 6: The influence of wind speed on the values of the number of revolutions of the wind wheel.