Turbocharger blade vibration: Measurement and validation through laser tip-timing

High Cycle Fatigue (HCF) of turbine blades is a major cause of failure in turbochargers. In order to validate changes to blades intended to reduce fatigue failure, accurate measurement of blade dynamics is necessary. Strain gauging has limitations, so an alternative method is investigated. A description of the tip-timing method is given, applied to turbocharger testing. The advantages and disadvantages of laser probes are assessed. Examples of output data and interpretation are presented and compared with computer simulation. It is shown that laser tip-timing technology gives a more complete view of turbine vibration than the alternative measurement systems.