Traveling Wave Excitation System for Bladed Disks

A traveling wave excitation system developed for the U.S. Air Force Research Laboratory's Turbine Engine Fatigue Facility is described. The traveling wave system was designed to simulate engine order excitation in stationary bladed disks for the purpose of identifying forced response localization and amplification due to mistuning. The system can test bladed disks of varying sizes and number of blades using either acoustic or magnetic excitation. A phase-shifting circuit reduces signal generation costs over purchasing separate function generators and allows amplitude and phase calibration of the exciters. Sources of errors in the traveling wave excitation are discussed and estimated. A finite element analysis shows that the forced response of a bladed disk is more sensitive to structural mistuning than to traveling wave excitation errors. The traveling wave excitation system is demonstrated on an 18-bladed disk, and experimental forced response results are presented. (Author)