| 摘要 |
A turbine flowmeter includes a rotor within a narrow-profile housing, the rotor having an axis of rotation aligned perpendicularly to the direction of fluid flow. The rotor employs a pair of oppositely directed, semi-cylindrical rotor elements disposed on either side of the axis of rotation, arranged in a generally rectangular configuration. Each element has a high drag front surface and a low drag back surface, the elements being twisted with respect to the axis so that at least a portion of a high drag surface is presented continually to the incoming fluid stream. Due to the wide disparity in drag between the front and back surfaces, and this twisted orientation, there is produced a continuous unidirectional net driving torque acting on the rotor, to prevent the occurrence of a null point, despite counter-resistance offered by the fluid. Furthermore, the gradually curving rotor protrudes minimally beyond the housing, and is able to rotatively adapt itself to the narrow spacing between pipe flanges. This effectively permits the insertion of the flowmeter into a space whose width is no greater than the width of the flowmeter housing alone. The placement of bearing surfaces and rotation-sensing instrumentation outside of the fluid flow facilitates maintenance of the flowmeter.
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