Importance

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Abstract

Flow is described by first variables related to a coordinate system, and by at least one second flow-related variable such as friction factor or Reynolds number unrelated to the coordinate system, wherein the first variables are separable or substantially separable from the second variables. The method includes determining average velocities of the fluid on two paths, or taking a first path measurement and at least one point measurement, selected such that combining the first path measurement and the second measurement forms an expression independent of the second variable. In one embodiment, first and second path measurements are combined in accordance with the velocity relationships given by the Pao equation to produce a flow measurement which is independent of the friction factor. A single calibration then allows the meter to be used on diverse conduits with different wall roughness or friction factor. The system also yields a non-invasive measure of the friction factor. A conventional flow meter may be set up by solving for flow profile and analytically determining a meter factor or appropriate measurement path. The measurements may be combined to eliminate the second variable, or to determine a chord on which the measured velocity equals the mean flow velocity across the conduit cross-sectional area. Alternatively, the two transit times may combined to determine a meter factor, or a known flow profile may be used to determine a single chord along which the transit time measurements relate to flow in a manner independent of the second variable.

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First Claim