Vibration Characteristics of Grouped Steam Turbine Blades

Abstract

The resonant amplitudes of grouped turbine blades were experimentally measured and theoretically calculated to determine the difference between calculated and experimental values. The blades were excited by an electromagnet, and the calculated values of the resonant amplitude distribution at the natural frequency were found to agree with the measured values. At some measuring points, a difference occurred between the calculated values and the measured ones, and in the worst case, the measured values became about twice the calculated ones. The calculated values also agreed well with the measured ones with regard to the direction of vibration and resonant stress. Therefore, if the operational exciting force can be estimated when designing the blades, the vibration amplitudes and stresses of the grouped blades can be calculated with some certainty. This is very useful for producing well-designed grouped blades.