Experimental Investigation on Damping Characteristics of Blade With Loosely Assembled Dovetail Attachment

The damping characteristics of blade with loosely assembled dovetail attachment are investigated experimentally. An experimental method and a test rig were presented to study the blade damping characteristics. In the measurement system, an external force is imposed on blade, to simulate the centrifugal force of blade. The dynamic responses of a group of simulation blades with different dovetail attachment angles were measured in consideration of variable simulation centrifugal force. The damping characteristics of a compressor blade with dovetail attachment were measured too. Some conclusions can be drawn from the experimental results. The resonant frequency increases with the centrifugal force, gradually reaches a certain value. The amplitude of resonant response decreases at the beginning and then increases with the centrifugal force increasing, there exists a special centrifugal force on which the effect of dry friction damping is the best. The change rate of the blade response in the range of neighboring optimal centrifugal force is obviously influenced by the dovetail angle. From the results of the last stage blade of compressor, we can find that the resonant amplitude retains a low level when the centrifugal force is from 1.5kN to 4kN.