Traveling-wave excitation and optical measurement techniques for non-contacting investigation of bladed disk dynamics

In this paper we present the design of an experimental facility for measuring the vibration of bladed disks, such as those used in turbomachinery. In particular, a method for simulating the effects of rotating a bladed disk past stationary sources of excitation is described, in which acoustic excitation sources in the vicinity of each blade receive harmonic signals with precise phase differences. Optical measurement techniques, including laser vibrometry and holographic interferometry, are used to observe the vibration, so that neither excitation sources nor measurement devices contact the test specimen physically. The result is a versatile test facility appropriate for the investigation of complex bladed disk dynamics, including the effects of small variations in parameters, such as blade mistuning.