Summary: | 碩士 === 國立中央大學 === 電機工程研究所 === 87 === In industry, flow velocities and volumes are both very important parameters, but it is not easy to be measured accurately. Traditional flowmeters have some limitations, such as high temperature, erosive, poison, inflammable environment. Hence, they are only used in certain types of fluid and may cause great inaccuracy or inconvenience. Moreover, highly accurate flowmeters are expensive in both price and maintenance. Consequently the motive of this dissertation is coming out.
The aim of this project is to measure flow velocity in open channel. The measurement theory is based on the Cross-Correlation Technique ,which calculates the relationship between two groups of signal. Two optical sensors are placed in line above the open channel and along the direction of flow. Because of the continuity of the flow, the time delay between the two received signals can be calculated by the cross-correlation function. The flow velocity can then be calculated by dividing distance by the time laterly.
The non-contative flowmeter using the cross-correlation technique can avoid the complexity caused by different fluid properties. A 8052 single chip is used in the circuit. This makes the other merits of the circuit. Programmable softwares in the chip are designed to replace complex hardware circuit, to minimize the size of the flowmeter, and to reduce the cost of the development and maintenance. Moreover, it can achieve real-time measurement and display of the velocity of the flow. The data can be transmited to the PC, the curves of cross-correlation function, flow velocity and volume are displayed on screen. It is very helpful in verifying the correction of calculation process and the results of measurement.
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