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Abstract: A prototype device for measuring the volumetric flow-rate by counting vortices has been designed and realized. It consists of a square-section pipe in which a two-dimensional bluff body and a strain gauge force sensor are placed. These two elements are separated from each other, unlike the majority of vortex apparatus currently available. The principle is based on the generation of a separated wake behind the bluff body. The volumetric flow-rate measurement is done by counting vortices using a flat plate placed in the wake and attached to the beam sensor. By optimizing the geometrical arrangement, the search for a significant signal has shown that it was possible to get a quasi-periodic signal, within a good range of flow rates so that its performances are well deduced. The repeatability of the value of the volume of fluid passed for every vortex shed is tested for a given flow and then the accuracy of the measuring device is determined. This quantity is the constant of the device and is called the digital volume (V p ). It has the dimension of a volume and varies with the confinement of the flow and with the Reynolds number. Therefore, a dimensionless quantity is introduced, the reduced digital volume (V r ) that takes into account the average speed in the contracted section downstream of the bluff body. The reduced digital volume is found to be independent of the confinement in a significant range of Reynolds numbers, which gives the device a good accuracy. [Copyright &y& Elsevier]

A torus could replace an orifice flow meter with the benefit of a lower pressure loss. The flow structure of a torus with an aspect ratio of three was scrutinized in a wind tunnel. This study details the vortical structures at 5, 7, 10 and 15 core diameters downstream of the torus. This paper also studied the drag coefficient of the torus. The Reynolds numbers based on core diameter and free stream velocity are 9 × 103, 1.2 × 104 and 1.5 × 104. Of particular interest is the resulting Strouhal number through the opening. This was evaluated through detailed flow turbulence characterization. • The wake structure behind a torus with an aspect ratio of three is experimentally studied by hot wire measurement. • Two regions each with a different Strouhal number are detected for the downstream location X/d = 5. • The Strouhal number almost remains constant over the range of tested Reynolds number i.e., 9 × 103 to 1.5 × 104. • The drag coefficient of the torus is much smaller than that of an orifice disc. • The value of the torus drag coefficient of the torus is between that of a sphere and a circular cylinder. [ABSTRACT FROM AUTHOR]