Strukturbeschreibung und Parameteridentifikation realer Radialturbinenlaufräder
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Beschreibung
The effects of blade mistuning regarding radial inflow turbine wheels are addressed in this work. Ideally tuned turbine wheels are of cyclic symmetric structure. However, manufacturing tolerances and wear will disturb the cyclic symmetry. Within the scope of this work the effects of such a degradation have been analysed experimentally and numerically. Concerning the experimental part, blade by blade measurements at standstill have been carried out for six radial inflow turbines in order to provide input data for different model identification procedures. As an outcome of this process the Subset of Nominal System Modes has been identified as the most valuable mathematical description in terms of model size and accuracy. Subsequently, this model was used in extensive probabilistic studies which led to the concept of Modal Density. Using the eigenfrequencies of a tuned rotor only, this concept allows for the identification of modes that are prone to strong amplitude amplification due to mistuning. The second part of this works aims to validate the model behaviour in terms of rotation. In order to separate the influencing parameters rotor speed, temperature and airflow, the measurements have been carried out in a spinning rig providing vacuum conditions. By means of a blade tip timing measurement system the response of every blade was captured. A comparison between measured and predicted blade vibration amplitudes gives satisfying results. Hence, the approach for model identification has been validated.
Autor*in
Peter Hönisch
Themen in »Strukturbeschreibung und Parameteridentifikation realer Radialturbinenlaufräder«
Blade Tip Timing Radialturbinenlaufräder Schwingung Turbine Verstimmung blade tip timing mistuning radial radial inflow turbine wheels transient turbine vibration