Project undertaken in course year 2017-2018 with the Dabiri Lab

Project Goal

Create an active braking system for vertical axis wind turbines to prevent damage to VAWTs during high wind speeds

Project Motivation

Improve VAWT appeal to wind farms, increase large scale clean energy production, increasing total power generation while increasing wind conditions in which VAWTs consistently operate


Despite better power density and other advantages compared to horizontal axis wind turbines, VAWTs suffer from reliability issues at wind speeds above 10 m/s

Failed VAWT blade

High Priority Requirements

  • Operate reliably at wind speeds up to 14 m/s

  • Maintain 90% of overspeed performance over one year maintenance cycle

Ethical Considerations

  • Magnetorheological fluid causes skin/eye irritation

  • Prevent pollution


Akin to a disc brake, this system mounts a disc to the shaft of the wind turbine, and that disc is contained in a magnetorheological fluid - a fluid whose viscosity changes when subject to magnetic fields. The case in which the fluid is maintained contains an electromagnet, which applies a magnetic field to the fluid when current is applied. The system is able to apply sufficient braking to enable a VAWT to survive at wind speeds up to 15 m/s, requiring only 10W to operate.

Pouring MRF

Magnetorheological Fluid (MRF) is used as the main focus of the project. It was selected for its magnetic properties and relatively low hazard potential

Magnetic Field Lines

Model showing a current running through a coil and generating a magnetic field that interacts with the MRF

How MRF works

The induced magnetic field causes particles in the MRF to align with the magnetic field lines, which results in a higher viscosity and slowing of the VAWT's rotation


SolidWorks model of the prototype

Machined prototype

The prototype was made of steel in order to better utilize the MRF's magnetic properties. The machining process heavily used a CNC

Finished prototype

The cylindrical base contains the disc and MRF. For an experimental setup, a hand drill was used to drive the shaft, leading to the rotation of the disc located inside hte base. Then, a current was applied to activate the MRF and increase viscosity of the MRF, which slows the angular velocity of the turbine

Test results

Data showing current input vs braking Torque of the prototype.

Student team

Future Work

  • Further investigate data gathering inconsistencies at low rotational speeds

  • Further understand the relationship between materials and their effect on rotational speed

  • Optimize material and attachment mechanism