| 摘要 |
Disclosed are apparatus for controlling fluid flow including a circumferential plurality of blades mounted between a parallel pair of axially spaced annular elements. The interstitial passages between the blades may be varied by the relative rotation of one annular element functioning as a ring actuator with respect to the stationary second annular element. The orientation of the circumferential blades is adjusted in unison by cam type engagements between one of the annular elements and the blades. An appropriate axial clamping force is applied to the assembly to frictionally secure the blades between the annular rings and to prevent end leakage of the fluid between the annular rings and the blade faces adjacent to the rings. Variation in the clamping forces acting on the blades as the blades are pivotally rotated to vary the passage cross sections therebetween may be controlled by providing pressurizable pockets in the blade faces adjacent to one or both of the annular elements. Such pockets may also be provided in one or both of the annular elements, alone or in combination with pockets in the blades. Fluid pressure is communicated to, or vented from, the pockets at various orientations of the blades, thus controlling the clamping force magnitude for any given blade orientation.
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