Reliability Evaluation of Shrouded Blading Using the SAFE Interference Diagram

Abstract

The SAFE Interference Diagram is shown to be useful in the design reliability evaluation of shrouded blading, including long-arc shrouding construction. This method provides an alternate method to the widely used Campbell diagram and also brings in more information for easier design evaluation. The SAFE diagram uses the natural frequencies of an entire bladed disk rather than individual blade or packet frequencies. In addition, it compares frequencies, mode shapes, and speed to evaluate whether a resonance occurs. Theoretical arguments are provided for the validity of the SAFE Diagram and its usefulness is shown by practical examples. This method provides an easier means to show why long-arc shrouding works and also when it might not.