| A vortex flowmeter is designed on the basis of Karman vortex street principle that is widely applied in the measurement of fluid flows; it develops speedily and is widely used from 1970s and 1980s in China. Contrasted with others, the vortex fiowmeter has incomparable virtues. However, the output signals of vortex fiowmeter contain high frequency, low frequency and random noise that can not be neglected in practical application, which made the precision of actual measure can not meet the performance criterions. Especially, the measurement of vortex flowmeter signals in low velocity is still a problem, because the vortex signals are too weak to be distinguished from noises in the state.As addressed above, by analyzing the features of wavelet transformation and vortex flowmeter signals, the wavelet threshold filtering method was used to process vortex flowmeter signals. And based on the conventional hardware and software threshold methods, an improved threshold selection method was proposed in this paper. The results from analysis and simulation of MATLAB showed that threshold filtering algorithm was effective to separate the vortex signal from noises, which was able to enlarge vortex flowmeter's measurement range and ensure its measuring accuracy.A vortex transducer was designed. The digital signal processors chip TMS320LF2407 is the calculation core of the transducer. The designs of transducer include the front-end circuit, the power supply module, the clock and replace circuit, the signal acquisition and processing module, the external extended ROM/RAM, the D/A conversion circuit, the serial interface, the CAN communication protocol interface and man-machine interface etc. The software design of the system was based on CCS and realized the basic functions of data processing and transmission. C language has better transplantation. The whole system was tested and the results were satisfied.
|
PDF Full Text Request