Effect 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 comers 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 flowmeters.