<p>The uncoupled phase-shifted single-passage simulation is commonly used for turbomachinery aeroelastic problems. However, it has difficulties in dealing with unconventional phenomena such as strong fluid-structure interaction effects as well as blade mistuning effects. Regarding mistuning effects, structural mistuning has been studied extensively while aerodynamic mistuning has received far less attention. &nbsp;There seems to be a lack of clear and systematic understanding of physical behaviour and mechanisms of mistuned bladerows, particularly in the context of the aerodynamic mistuning versus structural one. In the present work, direct fully-coupled method is adopted to investigate the dynamics mechanism of a mistuned oscillating cascade. Both structurally and aerodynamically mistuned cascades show that the blades would couple and oscillate at a unique frequency and a constant inter-blade phase angle regardless of the individual blade’s eigen-frequency. &nbsp;The vibration amplitudes of blades of a mistuned row are different when excited. For structural mistuning, the mode localization effect is seen to be responsible for a monotonic increase of cascade aeroelastic stability with mistuning. On the other hand, the aerodynamically mistuned cascade shows a stabilizing effect at small amount of mistuning but exhibits a destabilizing effect at large mistuning. Such non-monotonic tendency could be explained using the aero-damping decomposition by the influence coefficient approach. At low reduced frequency, there is a striking difference between the tuned and aero-mistuned cascade. Although the tuned cascade is stable, the aero-mistuned cascade may experience flutter. A close inspection of the aero-mistuned cascade flutter reveals that there are two oscillating waves forming a beating signal. This multiple-travelling wave flutter is in a remarkable contrast to the conventional monochromatic aeroelastic wave behaviour. It is also thought to be the first report of such kind of aero-mistuning related multi-wave aeroelastic instability phenomenon.</p>

Investigation of Mistuned Oscillating Cascade Using Fully-Coupled Method

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2021/volume/84898

Turbo Expo 2021

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.