Issue Section:Technical Briefs
Keywords:flowmeters, pipe flow, laminar flow, pressure measurement
Topics:Ducts, Flowmeters, Reynolds number, Laminar flow, Flow (Dynamics), Pressure, Pressure drop
A concept of the laminar flowmeter is based on the well-known relationship between laminar flow rate of fluid through a measuring element of length and pressure drop . Usually the measuring element is a capillary tube, capillary tube bundle, parallel plate bundle, or concentric annular duct (Fig. 1).
The pressure drop in the measuring element (“long duct”) consists of two components:
where: is a constant (depends on a duct cross-section shape), is the duct cross-sectional area, is the hydraulic diameter of the duct, is the incremental pressure drop number in a fully developed flow region (depends both on the duct cross-section shape and on the inflow conditions), is the distance between the flowmeter pressure...