DESIGN CONDITIONS FOR OPTIMAL DUAL BLUFF-BODY VORTEX FLOWMETERS

Examination of the performance of a large number of dual bluff body co mbinations leads to the conclusion that optimum repeatability of vorte x shedding may be obtained with combinations satisfying certain basic conditions. One possible condition is the coincidence of the positions of maximum vortex strength for the individual bluff bodies which make up the combination. The aim of this paper is to describe the results of a test of the above principle using rectangular bluff bodies. The f irst stage is to find the mathematical relationship between the positi on of maximum strength and the depth of a single rectangular bluff bod y. The next stage is to use this relationship to find which combinatio ns satisfy the above coincidence condition. These 'optimal' combinatio ns were then tested against a number of 'non-optimal' combinations as controls. The overall conclusion is that the above condition is just o ne of five conditions underlying the design of optimum dual bluff body vortex flowmeters.