3. Main stages of damper supports design
As noted above the preliminary design stage always includes a crytical speeds and mode shapes analysis. If a critical speed is within the engine operating range a frequency tuning is performed.
One of the most effective methods of critical speeds reduction is using of flexible elements in supports, which moves the critical speeds down from the operating range. But this arises a problem of passing the critical speeds when accelerating to the operating speed. Using of specific methods can help avoiding of dangerous vibrations.
On the other hand the vibrations can be caused by large rotor unbalance at the operating speed. If so the vibrations can be reduced by damping in supports.
Actual damping supports solve both problems - tuning and damping.
The support design process can be separated into the following stages based on parametric studies of the rotor dynamics analysis:
- Calculation of dangerous speeds.
- Taking of a decision on damper support using.
- Calculation of required support flexibility and damping.
- Choice of the support type.