CFD Analysis of a Wind Turbine to Check Output Power and RPM at 15 MPH

A client developing a compact wind turbine needed to know, before building a prototype, how much power the design would produce and how fast the rotor would spin in real wind. The design point was a 15 mph wind, the speed the turbine would see most often at its intended site.

Field testing is slow and expensive, and it only gives the final number, not why the design behaves as it does. Our computational fluid dynamics (CFD) model in Simcenter STAR-CCM+ shows both: it predicts the RPM, torque and output power at 15 mph, and runs at 20 and 25 mph show how the performance climbs with wind speed and where the aerodynamic losses sit, all before any metal is cut.

The study answers the two questions every wind turbine developer asks first: how fast will it spin, and how much power will it make?

The velocity field at 15 mph, at the top of this page, explains how the design works:

At 20 mph the same pattern grows stronger. The accelerated region around the rotor expands, the peak velocities climb and the torque rises with them, giving higher RPM and more output power. The runs showed the expected steep growth of power with wind speed, and the rotor kept working cleanly rather than stalling. The wake also stretches further downstream: if several units are installed close together, their spacing must respect it, or the downstream turbine sits in slow, disturbed air and loses much of its output.

The pressure field at 25 mph completes the picture. High pressure builds on the windward side, where the air piles up against the body and the advancing blades, while low pressure forms over the blade surfaces and in the wake. This pressure difference across the blades produces the torque that keeps the rotor turning.

The three runs gave the client the RPM and output power at the 15 mph design point and the performance trend up to 25 mph, with the aerodynamic evidence behind the numbers. That is a solid, low-risk basis for sizing the generator, setting expectations for energy production and moving to a prototype. Read more about the method in our article on CFD and FEA for wind turbines.