ZF – Harnessing the Power of the Wind

“It’s much easier to create a revolution than to maintain it.”

Jo Loenders, Product Management Engineer
ZF Wind Power

Harnessing the power of the wind is nothing new for humankind. Thedevelopment of the sail for ships allowed for travel and exploration around the globe.

There is also the classic image of a windmill, whether it be the large Post Mill style found across Europe or the multi-bladed wind pumps found across the Great Plains of the United States.

These allowed humans to settle into different areas by using the energy of the wind and transforming it into useful work, such as pumping water or milling grains.

While these technologies can still be used today, it is no longer the translation of wind energy into mechanical energy that is at the forefront of design but the translation in electrical energy.

In fact, wind power is growing worldwide becoming one of the largest sources of renewable energy. To continue to meet this growing need, large numbers of wind turbines are being constructed both on land and at sea.

As a business unit of ZF Friedrichshafen, ZF Wind Power is a leader in the design, manufacture, supply, and servicing of wind turbine gearboxes.

Since ZF Wind Power first entered the wind turbine market in 1979, its manufacturing plants have shipped more than 65,000 gearboxes powering more than 120,000 megawatt of installed wind capacity around the globe.

These gearboxes are a critical part of the turbine as they translate relatively slow moving rotation from the large blades to a much higher rotational speed needed for the onboard electrical generator.

These systems consists out of multi stage planetary and helical gear sets.

A challenge faced in their design is that as the gearbox operates there is a large amount of heat produced both at the bearings and at the gear mesh contacts.

If this heat generation is not balanced with proper cooling and lubrication, the excess heat will cause issues such as overheating of the surface resulting in failure mode scuffing.

This will ultimately cause the failure of the machine, and a significant financial cost for repair or replacement, as well as the chance for more catastrophic damage in extreme cases..

The use of SimcenterTM FlomasterTM software allows a significant streamlining of the development process.

From the very beginning, creating the fluid model is easy and intuitive. Model construction is done by simply adding predefined componentsto the schematic and connecting themas designed.

When it is necessary tomake changes to the model it is as simple as replacing components, changing connections, or editing in the Simcenter Flomaster model, instead of updating input data or even changing the coding in the Excel calculation sheet.

It is also possible to reduce the design time needed to size distribution lines for required flow rates.


In wind turbine gear boxes there is always more than one flow path that requires fluid flow.

These paths are rarely naturally equal with regards to pressure drop, so it is necessary to implement restrictions in some lines to ensure the flow is balanced. In Simcenter Flomaster, the Flow Balancing functionality allows this to be done directly instead of through a time consuming iterative design process.

For each flow path, it is possible to simply set the desired flow rate in the part that needs to be sized, such as an orifice, pipe, or valve, and the software calculates the required size.