Select Topic of Vortex Flow Meters
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timesVortex Shedding Tutorial
The vortex shedding flowmeter first emerged 25 to 30 years ago and has steadily grown in acceptance since then to be a major flow measurement technique. Its appeal is due, in part, to the fact that it has no moving parts yet produces a frequency output that varies linearly with flowrate over a wide range of Reynold’s numbers. The vortex meter has a very simple construction, provides accuracy (1% or better) comparable to higher price and/or more maintenance intensive techniques and works equally well on liquids and gases. In addition it is powered primarily by the fluid and lends itself more readily than other linear flow devices to two -wire operation. Comparing the vortex shedding flow meter to an orifice plate the former has higher accuracy and range ability, does not require complex pressure impulse lines, is less sensitive to wear and, for volumetric flow measurement, does not require the need to compensate for fluid density.
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timesEffect of bluff body shape on vortex flow meter performance
Frequency of shedding vortices in the wake of a bluff body is used to measure the flow rate in vortex flowmeters. A smooth bluff body shape may not generate stable vortices and needs sharp edges for the consistency of pulsed output. However, such bluff bodies give higher-pressure loss and drag force and therefore a need exists for optimising the body shape. In the present work, the flow over various body shapes in a pipe have been analysed using computational fluid dynamics to study the effect of body shape on pressure loss and drag coefficient. It is observed that the body shape with sharp corners have higher-pressure loss and drag compared to the cylindrical one. However, a triangular body shape with splitter plate or diamond shape has low coefficients of permanent pressure loss and drags compared to the other sharp cornered bodies and hence are better suited for use in the vortex flow meters.
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Last download: Sat Oct 01, 2016 07:43:38 AM