Note: A vortex cross-correlation flowmeter with enhanced turndown ratio

Abstract

In the present study, a novel dual sensor vortex cross correlation technique is suggested and implemented to extend the lower operating range of the flowmeter. The first sensor located at an optimum streamwise location of 0.85 times the width of the bluff body is employed to compute the vortex shedding frequency under high Reynolds number conditions. Under low Reynolds number conditions, when the strength of the vortex signal is poor, the outputs from the two piezoelectric sensors are correlated to compute the vortex convection velocity. This vortex convection velocity is used to compute the volume flow rate. This novel dual flow rate estimation technique has demonstrated its robustness under low Reynolds number flow conditions with a remarkable turndown ratio of 1:66 as compared to 1:20 for conventional vortex flowmeters.