Calculator Inputs
Formula Used
Where D is rotor diameter, R is rotor radius, n is rotational speed in rpm, and V is wind speed in m/s.
The page also estimates swept area, wind power, and expected output power using your air density, Cp, and efficiency inputs.
How to Use This Calculator
- Enter the rotor diameter and select meters or feet.
- Input rotor speed and choose rpm or rad/s.
- Provide wind speed and select the matching unit.
- Choose blade count to compare against a common TSR band.
- Add target TSR, air density, Cp, and drivetrain efficiency.
- Press Calculate TSR to show results above the form.
- Review the graph, assessment, and export the results as CSV or PDF.
Example Data Table
| Case | Diameter (m) | Rotor Speed (rpm) | Wind Speed (m/s) | Blade Count | TSR | Tip Speed (m/s) |
|---|---|---|---|---|---|---|
| Utility 3-Blade | 42 | 18 | 8.5 | 3 | 4.657 | 39.584 |
| Small Turbine | 6 | 220 | 11 | 3 | 6.283 | 69.115 |
| Water Pump Rotor | 4 | 70 | 9 | 12 | 1.629 | 14.661 |
Frequently Asked Questions
1) What is tip speed ratio?
Tip speed ratio compares blade tip speed with incoming wind speed. It helps engineers judge whether a turbine is rotating too slowly, efficiently, or too quickly for its aerodynamic design.
2) Why does TSR matter in turbine design?
TSR strongly affects aerodynamic efficiency, torque, noise, and blade loading. A mismatch between operating TSR and design TSR can reduce power capture and increase stress on components.
3) What TSR range is common for three-blade turbines?
Three-blade wind turbines often operate around TSR 6 to 8. Exact targets vary with blade profile, control strategy, generator behavior, and the intended balance between efficiency and structural loading.
4) Can I use feet, mph, or rad/s?
Yes. This calculator converts feet to meters, mph or km/h to m/s, and rad/s to rpm internally. The calculations are then performed using consistent SI engineering units.
5) Why is my TSR very low?
A low TSR usually means the rotor is turning slowly compared with the wind. Common causes include heavy loading, low generator speed, a high blade count, or strong winds relative to rpm.
6) Why is my TSR very high?
A high TSR means the blade tips move much faster than the wind. That can indicate light loading, aggressive speed control, or a rotor design intended for faster aerodynamic operation.
7) Does this calculator estimate power too?
Yes. It estimates available wind power and expected output power from swept area, air density, wind speed, Cp, and drivetrain efficiency. These power values are simplified engineering estimates.
8) Is TSR alone enough to judge turbine performance?
No. TSR is important, but performance also depends on blade aerodynamics, pitch, Reynolds effects, yaw error, control logic, losses, air density, and structural operating limits.