The Model Reduction Method of Grouped Blades

Abstract

As an important structure in turbine machinery, grouped blades are easy to damage due to large thermal loads and centrifugal loads. Once the characteristic frequency of grouped blades is equal to or close to the frequency of the exciting forces, the vibration of the grouped blades will become very severe. Therefore, it is very important to analyze the characteristic frequency of grouped blades accurately and quickly. This article aims to investigate the model reduction method of grouped blades, which can reduce the unknowns in the dynamic equations of grouped blades. And the efficiency of the modal analysis of grouped blades can be improved. Finally, the effects of the modal truncation number on the error of the natural frequency, the modal shape confidence factor, and the calculation time are discussed. Although the structure discussed in this paper is the disk with three blades, the derived algorithm can be applied to large-scale grouped blades. The study of this paper can serve as a reference for the design and validation of the widely used blade groups in the industry.