Flowmeter, a device for measuring fluid flow, Ultrasonic Flow Meter, as the name suggests, is a device that uses ultrasonic to measure fluid flow, so the question is, is the Ultrasonic Flow Meter really the same as the literal meaning? In the same way, how does it use ultrasound to complete the detection of fluid flow?
The principle of Ultrasonic Flow Meter--Introduction
Ultrasonic Flow Meter, the English name is Ultrasonic Flow Meter, is a use of the principle of velocity difference method to measure the liquid flow in the tube, can be divided into the external folder and pipe type, often with digital signal processing technology, multiple pulse technology, error correction technology, etc. to meet the environment, The purpose of enhancing its reliability has been widely used in the fields of chemical industry, electric power, petroleum, metallurgy and so on.
II. Ultrasonic Flow Meter Principle--structure
Ultrasonic Flow Meter is mainly composed of ultrasonic generator, ultrasonic receiver, electronic circuit, flow display and accumulative system. The ultrasonic generator is mainly used to produce ultrasonic wave and transmit it to the fluid; Ultrasonic receiver is mainly used for receiving ultrasonic wave after passing the fluid, ultrasonic wave is received to after the electronic circuit amplification, conversion and other processing in the form of electrical signals to transmit the flow to the display screen and the results displayed; Cumulative calculation of accumulated system complete flow.
Three, the principle of Ultrasonic Flow Meter
By detecting the effect of fluid flow on ultrasonic wave, the Ultrasonic Flow Meter uses the "Time difference method" to measure the liquid flow. First, using the probe 1 signal, signal through the tube wall 1, fluid, pipe wall 2 by the other side of the probe 2 received; in the probe 1 transmitter signal at the same time the probe 2 also emits the same signal, through the wall 2, fluid, tube wall 1 after the probe 1 received; Due to the existence of the flow rate of two times, there is time lag, Therefore, the flow rate can be obtained according to the time difference.
IV. Principle of Ultrasonic Flow Meter--Advantages and disadvantages
Because Ultrasonic Flow Meter uses ultrasonic wave to measure the flow of fluid, therefore, it can not only measure the conventional pipe flow, but also measure the flow of the pipeline which is not easy to be observed and not easy to contact. It can not only measure conventional fluid flow, but also measure the flow of fluid with strong corrosive, radioactive, flammable and explosive characteristics.
Ultrasonic measurement of fluid flow range is so wide, but it also has shortcomings. The Ultrasonic Flow Meter is limited to the temperature range of the measured fluid, at present, our country's Ultrasonic Flow Meter can only be used for 200 ℃ of the following fluids; Moreover, the measuring circuit of Ultrasonic Flow Meter is very complex, and if the measurement result is 1%, the accuracy of the measurement of sound velocity needs to reach the 10-5~10-6 order High requirements for measuring lines.
(1) The ultrasonic flow-address meter can be made into non-contact, that is, the measurement from the outside of the pipeline. Because there is no insertion in the pipeline inside the measuring parts, so there is no pressure loss, do not change the flow of the original fluid state, the original pipeline without any processing can be measured, easy to use.
(2) Wide measurement object.
Because the results are not affected by the viscosity and conductivity of the measured fluids, the flow rate of various liquids or gases can be measured. In the case of liquid flow measurement, including the measurement of corrosive liquids, high cat liquids and the flow of non-conductive liquids, especially suitable for measuring the water flow of large-diameter pipelines or a variety of canals, rivers, water flow rate and flow, in medicine is also used to measure blood flow.
(3) The output signal of the Ultrasonic Flow Meter is linearly related to the flow site of the measured fluid.
(4) Like other flowmeter, the Ultrasonic Flow Meter needs a certain length of straight pipe. General straight pipe length in the upstream side of the need to fod above, and at the downstream side of the need to around 5D.
(5) The accuracy is not too high, about 1%
(6) The effect of temperature on the speed of sound, generally not suitable for large fluctuations in temperature, the physical properties of large changes in the flow measurement, and secondly is not suitable for small flow, small diameter of the flow measurement, because at this time the relative error will increase.