Excitation Source outside the Main Flow Path for Low Pressure Stage Rotor Blade of Steam Turbine

Abstract

Low pressure stage blades of steam turbines generally possess a high aspect ratio and are prone to vibration. Many studies have been conducted to identify and eliminate the sources of blade vibrations in the main steam flow path. In the present study, we investigate a source of these blade vibrations. This source is located in an annular small recess outside the main steam flow path, and it rotates along the annular small recess. It induces blade vibrations at a frequency asynchronous to the steam turbine rotor's revolution. We have found that the influence on the blades is more significant from the wider width of this small recess than its deeper depth. Furthermore, we have tried to establish the criteria for eliminating this excitation source under specific steam turbine operating conditions.