AN ENERGY HARVESTING DEVICE FOR POWERING ROTOR LOAD MONITORING SENSORS

Open Access
Author:
Quintangeli, Michael Vincent
Graduate Program:
Mechanical Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
August 03, 2011
Committee Members:
  • Edward Smith, Thesis Advisor
  • Karl Martin Reichard, Thesis Advisor
  • Stephen Clarke Conlon, Thesis Advisor
  • Edward C Smith, Thesis Advisor
  • Christopher Rahn, Thesis Advisor
Keywords:
  • rotor
  • electromechanical
  • electromagnetic
  • pitch link
  • helicopter
  • energy harvesting
  • rod end
  • HUMS
Abstract:
Health and Usage Monitoring Systems (HUMS) are designed to improve safety, increase operational efficiency, and reduce the cost of owning and operating a helicopter. They are useful for monitoring many parts of a helicopter including engines, gearboxes, rotor components, and bearings. These systems are usually powered by battery or wired to onboard power, but some monitoring spots cannot use these power sources due to location or accessibility. A solution for these locations is to use energy harvesters to power the monitoring equipment. Energy harvesters convert mechanical or thermal energy into electrical energy. The ability to use self-powered wireless sensors has the potential to greatly simplify installation and lower the support costs for HUMS systems. One possible location for an energy harvester is the pitch link located on the rotor assembly. Using the Blackhawk helicopter pitch link as the design case, an energy harvester was designed to fit inside the pitch link rod end to power a load monitoring sensor. An electromagnetic energy harvester was designed with a goal of harvesting 1 mW of electrical power from the motion of the pitch link. The energy harvester must be able to withstand the rotating environment and must also be able to fit inside the pitch link rod end of the Blackhawk helicopter. A dynamic model was formulated using Newtonian Mechanics to characterize the pitch link motion. The dynamic model proved there was sufficient motion for a simple electromagnetic energy harvester. The design parameters of the energy harvester were optimized using a non-uniform magnetic field model. An energy harvester was built to validate the theoretical model and to test the power output of the system. This energy harvester was tested on a shaker and was able to generate sufficient power with a maximum value of 2.2 mW at 1.2 g base acceleration. The theoretical model was able to predict the power output and voltage signal accurately. The energy harvester was also tested in a rotating environment, but it was only able to generate 0.82 mW at 8.5 g base acceleration. The large friction force from the resulting centrifugal force is believed to have caused the decrease in power. Some improvements were given to achieve the 1 mW goal such as using ball bearings to decrease the dissipation of power due to friction.