The paper begins by reviewing earlier work on the development of optimal dual bluff body vortex flowmeters. The five possible basic conditions underlying optimum vortex shedding from arrangements of two rectangular bluff bodies in tandem are then discussed. These conditions are then used to define optimal triple bluff body combinations where at least one of the two dual combinations which make up the triple is optimal. The performance of optimal triple combinations, non-optimal triple combinations, optimal dual combinations and an optimal single bluff body were then compared using a scan test. Here the vortex field downstream of a given combination was measured as a function of x, y position coordinates at a given free stream velocity and turbulence level. The results of this scan test are presented and are used to select three optimal combinations for further testing. A performance test was then carried out on these three optimal triples, the two optimal duals and the optimal single defined earlier. In a performance test, the sensor was first fixed at a position corresponding to optimum vortex shedding. RMS vortex velocity, signal-to-noise ratio, meter factor and a percentage frequency standard deviation were then measured over a range of free stream velocities and at medium and high turbulence. The results of this test are presented and show that the triple combinations perform better than the duals which in turn perform better than the single bluff body.
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