| 摘要 |
The invention relates to the use of low-density granular fill with a specific gravity less than 1.5, placed in hollow cavities built into turbomachinery blades, vanes, and shafts. The granular fill provides effective damping at lower frequencies than conventional passive damping treatment due to its low bulk compressional sound speed. Selected materials used for the granular fill treatment are chosen for specific turbomachinery needs, including temperature of operation. Rotation speed is also a factor because it induces on the granular material an apparent hydrostatic pressure associated with the centripetal acceleration, and sound speed in granular materials is a function of pressure raised to the power 1/n. Preferred designs for placement of low-density granular material in appendages and shafts are found using an iterative design tool based on the Direct Global Stiffness Matrix method.
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