The dynamic behavior of friction dampers at the base of turbine blades was investigated on behalf of Siemens.
A simulation analysis should take construction details more closely into account and should be optimized; for example, the spatial distribution of the contact pressure.
Using Ansys Mechanical, a detailed model was created to capture the dynamic response and contact behavior of the blade and dampers.
With the analysis concept developed by CADFEM, Siemens is able to further optimize the use of friction dampers at the base of turbine blades.
The dynamic behavior of friction dampers at the base of turbine blades was investigated on behalf of Siemens. The friction damper is used to reduce vibrations and thus increase the service life of the turbine blade. The analytical approaches used so far to investigate the behavior of the friction damper and turbine blade reflect their essential properties well. However, they are not able to take design details into account, such as the spatial distribution of contact pressure.
With the analysis concept developed by CADFEM, Siemens is able to further optimize the use of friction dampers at the base of turbine blades. Thus, the analytical solution can be verified and extended by examining the calculated load transfer. For example, the transient vibration analysis with Ansys Mechanical has largely confirmed the previous assumptions regarding the sliding paths. In addition, the geometric resolution of the contact distribution complements the analysis and, if necessary, further detailed information can be determined.
Using Ansys Mechanical a detailed model was considered to determine the relevant vibration shape and contact behavior between the blade and the damper. To achieve this the nonlinear contact of the friction damper was resolved in a location- and time-dependent manner. The power transmission between the blade and damper was analyzed by evaluating the contact behavior and the sliding paths during the vibrations. This made it possible to determine the power loss due to damping, which was extracted from the vibrating system by looking at how the turbine blades were prevented from oscillating.