| The Gas-liquid two-phase flow shows strong non-stationary characteristicsin flow process, simple frequency domain analysis or simple time domain analysisisn’t good for analysis the signals’ characteristics, so time-frequency analysis isintroduced. Time-frequency analysis can reflect the intensity and distribution densityof the two-phase flow pressure signals’ energy. The bubbly flow energy was mainlydistributed in the high-frequency band (15Hz-35Hz), which had the lowenergy-intensity. The slug flow energy was mainly concentrated in low-frequencyband (0Hz-5Hz) and high-frequency band (10Hz-35Hz), the energy was increased.The plug flow energy was mainly concentrated in the low frequency ranges0Hz-5Hz,energy intensity was the largest of the three flows. The main research andachievements of this paper as follows:(1)The signals were got by multi-hole orifices plate flow meter, through signalpreprocessing and then analyzed by STFT, wavelet transform, HHT, AOK. Thetime-frequency spectrum which was retained by the four methods showed signals’time-frequency domain characteristics, also could read the energy density andintensity. Comparing the different methods, the result showed that STFT had the lowresolution, it couldn’t meet the high time-resolution and high frequency-resolutionrequirements, wavelet transform had higher-resolution than STFT, but thefrequency-domain had aliasing. The different frequency and amplitude informationof original signal were well decomposed by HHT, so the instantaneous frequency andinstantaneous amplitude change over time was shown clearly in the spectrum image.AOK got over the cross-interference term’s impact of the quadratic time-frequencyanalysis, retained the time-frequency distribution of the component. HHT and AOKcan clearly see the slug flow signals’ energy distribution in three band ranges.(2)Analysis the dynamic characteristic of gas-liquid two-phase flowmeasurement with three different throttling device. Dynamic differential pressuresignals were collected by three differential pressure flow meter whose throttling device is venturi tube and multi-hole orifices plate and V-shaped inner. Using AOKspectrum to analyze the dynamic differential pressure signals, studied the signal’stime-varying characteristic of differential flow type from the spectrum charts. Itshowed that: multi-hole orifices plate flow meter had a good balance performancewhich could balance the energy of the signal. In the spectrum, the signal energy wasdistributed balance on the timeline. Multi-hole orifices plate flow-meter was good atreducing noise. The analysis also found that the hole diameter of the multi-holeorifices plate had a great impact on obtain the two-phase flow pressure fluctuationsignals.(3)The gas-liquid two-phase flow signal was analyzed by Adaptive Chirplettransform. Research the number of signal decomposition. After decomposition, theratio of the residual energy of signal and total energy was kept less than10%toensure that useful components of the signal was completely decomposed. Thetime-frequency spectrum which was obtained through Chirplet transform showed thedistribution of time-frequency component signal and didn’t have cross-interferenceterms， it had high resolution. By extracting characteristic variables from thetime-frequency spectrum, the scatter diagram of the characteristic combinationinformation was obtained. The scatter diagram combined with the fuzzy recognitionmethod to design the gas-liquid two phase flow pattern fuzzy identification system. |
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