Disk design methodology for reducing blade vibration in turbine engine rotors

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Disk design methodology for reducing blade vibration in turbine engine rotors

Baik, Sanghum / Castanier, Matthew P. / Pierre, Christophe

In this work, a straightforward yet powerful design methodology for bladed disks was presented and applied to two example systems. The key contributions and conclusions are summarized as follows. First, it was shown that a reduced-order vibration modeling method, combined with an energy-based estimator of dynamic stress in each blade, makes it feasible to perform a design optimization process that accounts for the effects of rotation speed and blade mistuning on the critical stress levels. Second, it was demonstrated that by optimizing only the disk geometry with just a few design variables, it is possible to contain the worst-case mistuned blade stress levels below a safe limit defined on the Goodman diagram, albeit with a minor penalty in increased weight. Third, it was found that the optimized disk geometry for each case generally featured an increased rim thickness and a decreased web thickness. Physically, this makes sense, because a thicker rim will tend to decrease the exchange of vibration energy among blades, thus reducing the possibility of many blades feeding energy to one large-responding blade. Furthermore, this trend suggests that it may be possible to develop some general disk design guidelines for reducing mistuned blade stress levels. Overall, the results obtained in this initial study are promising. Nevertheless, the design process might be significantly improved by using more design variables, different optimization techniques, or alternative stress estimators. These issues will be investigated in future research.