A novel turbine blade design and manufacturing approach developed by NASA provides a significant reduction in turbine blade resonant vibration. This innovation addresses the unique resonance vibration challenges of conventionally machined turbine bladed discs, or blisks. Additive manufacturing is used to make this unique structure.
The design approach uses an internal column manufactured as part of the blade that is optimized such that the dynamics of the blade damper system are rearranged and reduced according to the well-known science of tuned mass-absorption (TMA). The TMA concept has been implemented successfully in applications ranging from skyscrapers to liquid oxygen tanks for space vehicles. Indeed, this theory has been conceptually applied to bladed-disk vibration, but a practical design has not previously been reported.
The NASA innovation addresses another important challenge for turbine blade vibration damper designs. All existing blade damper solutions are essentially incapable of being reliably predicted, so an expensive post-design test program must be performed to validate the expected response. Even then, the actual magnitude of the response reduction under actual hot fire conditions may never be known.
The dynamic response of this tuned-mass-absorber design is both substantial and can be analytically predicted with high confidence, and thus the response can be incorporated fully into the upfront design process.
Prototypes have demonstrated a 50 percent reduction in resonant vibration. The innovation also enables improved predictive modelling of the resonant behavior of new blisk designs because the tuned-mass absorber acts as a linear system. In contrast, modelling of conventional blade dampers is extremely complex, and therefore, requires an expensive iterative test program dedicated to validation of the damper design.