| 摘要 |
A velocity measuring instrument of the type having a rotatable, counterweighted, spring-controlled vane and pointer assembly in which the outlet aperture for the fluid is contoured exponentially or logarithmically to present an exit flow area that varies as a function of vane position for linearizing the movement of the vane and pointer assembly in response to the pressure of the fluid on the vane. In one embodiment a true logarithmically varying area port is provided. In other embodiments, two or more openings of varying area or geometry are configured to approximate a logarithmic outlet aperture. A baffle may be provided on the exterior of the case to prevent fluid from entering the outlet aperture, and the interior of the case may be contoured adjacent to the outlet aperture and along the path of the vane to provide a variable leakage path clearance between the vane and the case. A grease-coated surface that contacts the vane and pointer assembly provides viscous damping to prevent pointer oscillation.
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