Development of Novel Ultrasonic Monitoring Techniques for Improving the Reliability of Wind Turbine Gearboxes

In this work, an ultrasonic method was developed to detect lubricant on rolling bearing raceways and also the load imparted by each of the rolling elements onto the raceways. It has been implemented both in the lab and an operating wind turbine. Sensors were mounted outside the raceway and sound waves reflected from the inner face. The ratio of reflected ultrasound to transmitted (Reflection Coefficient, R) was used to infer the raceway interface condition whilst the change in time of flight of ultrasonic waves was used to deduce the deflection of the raceways and subsequently roller load. Features observed in the field measurements include variation of roller load across different rollers within a complement, variation of roller load and lubrication along with turbine operation and various bearing lubrication condition.