Research On Wide-Beam Ultrasonic Flowmeter

The Wide-beam ultrasonic flowmeter researched in this thesis substitutes Lamb-wave for narrow-beam ultrasonic in order to improve on some insufficient which exist in the traditional narrow-beam ultrasonic flowmeter to a great extent.In this thesis the theory of the Lamb-wave and the method for Lamb-wave emission is studied. The theory analyses about parameters of the transducer which is used to emit Lamb-wave are done. The concrete circuit is designed. Microprocessor MSP430F448 is the core of the whole system. Based on the characteristic of the Wide-beam ultrasonic flowmeter, automatic gain control amplifier and the tracking band-pass filter are devised. In order to use conveniently, power can be 220VAC or lithium battery.The technology of frequency doubling and phase shifting of FPGA is used to measure accurately the ultrasonic wave transmit-time in the case of low frequency clock input. The wide-wave ultrasonic flowmeter has the unique second channel to automatically adjust the zero point drift.Experiment proved that the range of wide-beam ultrasonic flowmeter receiving signal is much wider than the traditional ultrasonic flowmeter.