Gas-Liquid Two-Phase Flow Bi-Parameters Measurement Based On The HHT And SVM

Gas-liquid two-phase flows exist in fields such as petroleum, chemistry, metallurgy, medicine and power industries. Two-phase flow parameters measurement is very important to the national economy for and production safety. At the same time, the process of two-phase flow is a quite complex and the measurement parameters is quite difficult.Flow regime and void fraction are important parameter in gas-liquid two-phase flow, the relation of differential pressure signal coming from Venturi tube and the flow regime of gas-liquid two-phase flow was studied in this paper, A kind of flow regime identification method of gas-liquid two-phase flow based on Hilbert-Huang Transform and fuzzy inference was put forward, the familiar flow regime identification of gas-oil and gas-water two-phase flow was achieved. Moreover, void fraction estimate means based on HHT and SVM (Support Vector Machine) was bring forward by analyzing the relation of fluctuant element, balanced element of differential pressure signal and void fraction, this means can realize the study in the case of few samples, and has good popularization ability. The main research achievement is showed as follows:1. Differential pressure signal filter method based on HHT was put forward, it is easy to lost useful information in signal by adopting routine filter method due to the differential pressure signal of two-phase flow has intense nonlinear characteristics. Make use of the band-pass filter characteristics of HHT, effective filter for bubble flow, slug flow, churn flow and annular flow were achieved. The results show that after filter, signal can keep good local character and nonlinear element.2. Time-frequency analyze for two-phase flow signal was achieved using HHT, it make researching signal in frequency domain and time domain respectively possible by analyze the margin spectrum,instantaneous energy of different flow regime signal. It can simultaneously analyze the change of signal in time-frequency domain Using Hilbert-Huang spectrum of signal, namely know the frequency element and intensity at each moment of signal distinctly. Thus it can analyze the signal character in different flow regime more directly.3. It was find its energy distribution has great difference for signal in different frequency scope that By researching HHT results of different flow regime differential pressure signal, for the sake of describing these difference quantitatively, define the energy ratio of signal in different frequency scope as characteristic variable, flow regime process method based on HHT was bring forward and corresponding flow regime graph was found by analyzing the energy ratio of different frequency. For describing flow regime relevantly much more, fuzzy inference ruler was set up using found flow regime graph, thereby exact and external flow regime identification was realized. In specially, it is significative for flow regime identification in transitional region.4. Signal had been decomposed as two parts after HHT, one is different IMF(Intrinsic Mode Function) that represents the fluctuant element, and the other is residual which reflect stationary element or trend of signal. They were find that fluctuant element is relative to void fraction closely, so do residual and flux. From this, void fraction estimate means for gas-liquid two-phase flow based on HHT and SVM was put forward. Experimental results of gas-oil and gas-water two-phase flow in pipe with different inner diameter show that this method has high precision, and it is influenced rarely by experimental condition so use easily.