| 摘要 |
A leaf seal 10 in a rotary machine is located between a higher pressure region 14 and a lower pressure region 16 of the machine. Blow-down forces are greater on the lower pressure side 16 of the leaf seal 10 than on its higher pressure side 14, resulting in greater inward deflection of the leaves 20 on the lower pressure side 16 of the seal than on its higher pressure side 14, leading in turn to greater wear of the leaves and the contacting rotor surface 44 on the lower pressure side 16 of the seal. To counteract this, the free ends 36 of the leaves 20 can be given a tapered profile 42 to gradually reduce the length of each leaf 20 over its width 'w' from its higher pressure side 14 to its lower pressure side 16, so that the leaves 20 are free to deflect under the blow-down forces by the amount of their reduction in length (a maximum of 'x'), before they contact the rotor surface. As an alternative to profiling the rotor-contacting ends 36 of the leaves, the leaf-contacting surface 44 of the rotor 12 can be given a tapered profile 46 in a mirror- reversed version of the leaf-end profile 42. The tapered profile of either the free ends 36 of the leaves 20 or the leaf-contacting surface 44 of the rotor 12 can either be linear (42, 46 in Fig. 2) or non-linear (48, 50 in Fig 3).
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