报告题目：ANOMALOUS VIBRATION RESPONSE OF AN INTENTIONALLY MISTUNED LPT ROTOR
摘要：As part of the European Project ARIAS, the wind tunnel facility at the Centro de Tecnologías Aeronáuticas was used to perform a set of experiments to study the effect of intentional mistuning on the forced response of an aerodynamically unstable low pressure turbine rotor. The intentional mistuning patterns were implemented by adding a small extra mass to some of the blades. The forced response of the rotor was therefore expected to show two resonance peaks with similar amplitudes, corresponding, respectively, to the vibration frequencies of the blades with and without added mass. But, on the post-processing of the measurements, some anomalous behavior was observed. Near resonance the system response was synchronous with the forcing, and the frequency sweeps exhibited two resonance peaks, but it was found that the two peaks were clearly different, with the peak at lower frequency showing a much higher vibration amplitude than the high frequency peak, and with some blades responding at both frequencies with a similar amplitude. In order to give a correct interpretation of the experimental results, a reduced order model is derived that takes into account only the traveling wave modes coupled by the mistuning. This model, although extremely simple, is capable of reproducing the unexpected behavior of the experiments, and gives a clean explanation of the system response. It is shown that the relative size of the mistuning with respect to the frequency difference of the involved traveling wave modes is the key parameter for the appearance of this phenomenon.
Carlos Martel is Professor of Aerospace Engineering at Universidad Politécnica de Madrid (Spain) since 2009, where he also completed his PhD in Applied Mathematics in 1995. His research activity started in the field of nonlinear dynamics and pattern formation applied to basic fluid mechanics problems (convection, water waves, boundary layer). In the past 20 years he has been involved in the study of different aeroelastic problems in turbomachinery in close collaboration with the industry, mostly related to the analysis and description of mistuning effects in the flutter and forced response vibration of rotors. He has authored more than 70 scientific and technical papers on peer reviewed journals, conferences, and technical reports.