Runner Diameter (\( D_{\text{run}} \)):

\[ D_{\text{run}} = 39 \cdot \frac{\sqrt{H}}{N_t} \]

Where:

• \( D_{\text{run}} \) is the runner diameter, in meters (m).
• \( H \) is the head, in meters (m).
• \( N_t \) is the shaft speed, in revolutions per minute (rpm).