Modal testing of the Francis-99 runner

The Francis-99 low specific speed Francis runner has undergone much study in the years since it was first made available to public. High Head Francis(HiFrancis) project, hosted by Waterpower Laboratory at NTNU, have conducted multiple experimental campaigns supply validation data for numerical simulations of RSI phenomenon runner. Due amount instrumentation on board an asymmetry exists structure that naturally affects structural response From analysis been found exhibit natural modes vibration, within narrow frequency bands. In order validate identified frequencies, with their corresponding mode vibration and amplitude, experiment conducted. utilises piezo electric patches mounted hub excite a defined trailing edge all blades is measured 1D Laser Doppler Vibrometry scanner. Preliminary results are shown demonstrate possibilities presented method.