**8.1 Velocity streamlines**

Here, the velocity streamlines for various pitch angles (0,3,5, and 10 degrees) and TSR (5,6,7,8, and 9) are presented. Streamlines track the path of the wind as it flows across the blades. The least obtained velocity was 7.27 m/sec. This velocity (7.27 m/sec) is essential as it directly affects how much energy is extracted from the wind [10] shows some velocity streamlines for non-separated flow, as the turbine is optimized. Our results indicate non-separated flow at optimal TSR. **Figure 12** shows the velocity streamlines for various turbine blade configurations. The five rows of the image are the TSR 5, 6, 7, 8, and 9, and the four columns are pitch angles of 0, 3, 5, and 10 degrees. Every image at location {TSR, Pitch} corresponds to that particular input condition.

### **8.2 Pressure contours at root of the blade: CFD-Post**

The pressure contours are directly responsible for torque generation by the blade. Typically, the bottom portion should have high pressure, followed by the top side, which has low pressure. This net pressure difference creates lift at an angle. A portion of this lift will assist in blade rotation. One can note that as the pitch angle is high and TSR is increased, the low and high-pressure regions shift, and the blade will stop generating torque, or if pitching is increased further, it will generate reverse torque. This unique feature can make the blade stop rotating in stormy or very high TSR conditions by moving the blade to this appropriate zero torque angle. One can also note that the blade produces maximum torque when the angle of attack is close to 5 degrees, which depends on TSR and pitch angle. The two contours shown here are for the root (S815), **Figure 13** and tip (S826), and **Figure 14** of the blade. The five rows of the image are the TSR 5, 6, 7, 8, and 9, and the four columns are pitch angles of 0, 3, 5, and 10 degrees. Every image at location {TSR, Pitch} corresponds to that particular

**Figure 12.** *Velocity streamlines for varying pitch and TSR.*

input condition [10] shows pressure contours where the wake (region of low pressure) is visible at the tail end of the airfoil. However, the blade as a whole is not simulated, and this produces slightly differing pressure contours in our case but is still consistent with our results.
