Patent ID: 7617738
Filing Date: 2009-11-17
Classification: G01F

Abstract:
1. A method for measuring a flow rate of a fluid moving in a tube which comprises the steps of: (1) preparing a flowmeter comprising a set of a first upstream side shock wave-generating piezoelectric element and a first downstream side shock wave-receiving piezoelectric element and a set of a second downstream side shock wave-generating piezoelectric element and a second upstream side shock wave-receiving piezoelectric element arranged on a surface of the tube under such condition that the shock wave-generating piezoelectric element and the shock wave-receiving piezoelectric element of each set are arranged along a fluid-moving direction apart from each other at an equivalent distance; (2) causing movement of the fluid in the tube and, while the fluid is moving, an impulse voltage with steep rising edge or steep falling edge is applied to the first shock wave-generating piezoelectric element to generate a shock and transmit the shock through a wall of the tube into the moving fluid so as to produce a shock wave in the moving fluid; (3) transmitting the shock wave through the moving fluid and receiving the transmitted shock wave by the first shock wave-receiving piezoelectric element through the wall of the tube; (4) while the fluid is moving, an impulse voltage with steep rising edge or steep falling edge is applied to the second shock wave-generating piezoelectric element to generate a shock and transmit the shock through the wall of the tube into the moving fluid so as to produce a shock wave in the moving fluid; (5) transmitting the shock wave generated in the step (4) through the moving fluid and receiving the transmitted shock wave by the second shock wave-receiving piezoelectric element through the wall of the tube; (6) processing data of the wave received in the step (3) and data of the wave received in the step (5) to obtain data of a composite wave and detecting a predetermined characteristic value from the data of the composite wave; (7) preparing a relationship between a moving rate of the fluid and the same characteristic value of data of a composite wave corresponding to the moving rate separately; and (8) comparing the characteristic value of data of the composite wave obtained in the step (6) with the relationship obtained in the step (7), to calculate the flow rate of the fluid of the step (2).