Session: 23-11 Seal Rotordynamics

Paper Number: 151626

Validation of Effectiveness of Swirl Brakes and Fluid Destabilization Force Prediction Method by Excitation Test During Load Operation of Large Steam Turbine 

In turbomachinery such as steam turbines, sealing technology has been advanced to improve performance. On the contrary, the fluid destabilization force generated in the blade and labyrinth seal has increased, and the risk of unstable vibration called steam whirl has become apparent.
Although swirl brakes are widely used as a stabilizing device against the fluid destabilization force, there is no case in which the stabilizing effect has been quantitatively validated in actual steam turbines.
Therefore, the damping ratio of rotor system under load operation was evaluated under 2 conditions with and without swirl brakes for a large steam turbine of 100MW class. By comparing the evaluation results of the damping ratio, the stabilizing effect of swirl brakes was validated by actual measurement.
In order to evaluate the damping ratio accurately, a hydraulic exciter was installed at the bearing casing, and the turbine rotor was excited during load operation, and the response of the first natural frequency mode was measured.
Furthermore, the relation between the load and the damping ratio was confirmed by carrying out excitation tests with the turbine load as a parameter and estimating the damping ratio of rotor system. The validity of the prediction method of fluid destabilization force based on CFD (Computational Fluid Dynamic) analysis was also confirmed by comparing the measurement results of the damping ratio under load change with the prediction analysis results.
 

Presenting Author: Makoto Iwasaki Mitsubishi Heavy Industries

Presenting Author Biography: I graduated from Kyushu University in 2011 and joined MHI (Mitsubishi Heavy Industries). Since then, I have been engaged in design and R & D as a mechanical vibration engineer for 13 years.
My specialty is flow-induced vibration and rotor dynamics, and my main product areas include large steam turbines, gas turbines, compressors, and turbo chillers.
In recent years, I have presented a paper on fluid destabilization forces generated in labyrinth seals at TurboExpo. I am also engaged in research on dynamic characteristics of oil film bearings, electro-mechanical coupled vibration of motors and generators, and magnetic bearings.

Authors:

Makoto Iwasaki Mitsubishi Heavy Industries
Kenichi Murata Mitsubishi Heavy Industries
Naoto Omura Mitsubishi Heavy Industries
Teruaki Yamawaki Mitsubishi Heavy Industries