System and method for sensing fluid flow using acoustic arrays.

摘要

Piezoelectric elements (62a, ..., 62e; 71(1,1), ..., 71(20, 20); 92(1, 1), ..., 92(50, 50)) in a transducer array (70; 90) are individually excited and used to sense the back-scattered signal from fluid flowing within an interrogation volume (54; 66, 68; 76, 78). The array is preferably a 2-D phased array with a pitch no greater than one-half the acoustic wavelength of the interrogation signal. By activating the transducer elements as a pattern of concentric rings as viewed from a point of interrogation, and by suitable phasing and range-gating of an interrogation signal, a substantially spherical interrogation volume (SIV) is created. The return signal from the SIV provides an isotropic indication of the speed of flow of the fluid. The focussing distance along an interrogation axis can be changed by changing either the size of the aperture created by the pattern of activated elements or their relative phasing. The interrogation direction can be angled off-axis by activating the transducer elements in a pattern of concentric ellipses. The interrogation axis itself may also be moved off-center by translating the pattern of activated elements. By deforming the activation pattern of the transducer elements from concentric rings to concentric ellipses, the long axes of ellipsoidal interrogation volumes (EIV) can be rotated. The back-scattered signals from these rotated ellipsoidal interrogation volumes indicate the direction of fluid flow.