Session: 27-06 Lateral-Torsional, Cracked, and Bent Rotordynamics

Paper Number: 103555

103555 - Experimental Evaluation of Damping for Torsional Dynamic Calculations of Turbo Machinery Shaft Line 

The increasing demand of operational flexibility in power generation requires a deep understanding of the dependency on operational conditions of the main design parameters.

Torsional damping is an important calculation input for the dynamic design of a power generation shaft train. Its importance arises from the common idea that torsional damping is usually very low compared to lateral damping, therefore torsional vibration represents a dangerous phenomenon to avoid.

Standard rotordynamics approach considers steady state frequency response calculations with damping values derived from legacy design rules. While the assumption of low damping leads to a conservative approach to evaluate stress and thus a high safety factor with respect to the real engine, calibrated values allow for higher precision during the design phase facilitating optimization of, for example, rotor weights and volumes to earn operational efficiency. Moreover, the flexibility demand, from a mechanical integrity point of view, necessitates the study of how materials utilization factor is affected by continuous engine operation away from nominal design conditions (power, temperature gradients etc).

The focus of this paper is to provide a comparison between damping values at different operational conditions and to investigate limitations of the standard method, through the use of experimental data and numerical analysis.

Final goal of the paper is to assess how a linear rotordynamic shaft line model can be improved to more realistically predict the engine dynamic torsional behavior, in order to define more accurate procedures to support the design optimization.

Presenting Author: Giovanni Pallini Ansaldo Energia

Presenting Author Biography: Mechanical Engineer, Phd

Authors:

Luigi Carassale University of Genova
Stephen Gillon Ansaldo Energia
Giovanni Pallini Ansaldo Energia