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Application Of Higher-order Statistics Technology To The Measurement Of Two-Phase Flow

Posted on:2006-02-25Degree:DoctorType:Dissertation
Country:ChinaCandidate:M Y ZhaoFull Text:PDF
GTID:1118360152496431Subject:Control Science and Engineering
Abstract/Summary:PDF Full Text Request
Two-phase flow system is a complex, nonlinear and dynamic system which exists widely in processes such as power, chemical, petroleum and metallurgy industries. Research of hydrodynamics, mechanisms and accurate measurement of parameters in two-phase flow are very important for the development of modern industry.In this thesis, the high-order statistics technique is applied for the parameter measurement of two-phase flow. The non-gaussian character of differential pressure fluctuation signal is picked up. Meanwhile, the bispectral estimation are used for the identification of the flow regimes of gas-solid fluidized bed and gas-liquid two-phase flow. The experimental results show that the presented methods are effective. The major contribution of this work is as follows:● A new method of the application of high-order statistics technique to analyze the pressure fluctuation signal of gas-solid fluidized bed is proposed. The pressure fluctuation signals obtained from the pressure transducer are analyzed by using bispectral method and the average bispectral amplitude is regarded as an eigenvalue. The non-gaussian characters of different flow patterns are picked up. Combined with fuzzy pattern recognition theory, the fuzzy identification criterions of flow patterns are established. The experimental results show the proposed method can suppress Gaussian noises of signal and is effective for flow pattern identification.● Higher-order statistics technique is applied to analyze the differential pressure fluctuation signal of gas-liquid two-phase flow. Based on bispectral method, the non-gaussian characters of different flow patterns are determined, and the bispectrum of different flow patterns are obtained. According to the model of soft-sensoring technique, an identification method applied to the gas-water two-phase flow is presented. The results show that the method is effective.● Based on infrastructure technique, a software for measurement of two-phase flow system is constructed. A stable data acquisition systembased on this software is developed. Generic programming is applied to the signal processing algorithm library.● For improving the speed of bispectral estimation algorithm, a new high-speed parallel algorithm for bispectral estimation is presented. Based on FFT parallel algorithm, the characteristics of bispectral estimation algorithm are studied. Meanwhile, a parallel computation model more suitable for bispectral estimation is proposed. The algorithm is implemented on smp parallel computers, its validity is comfirmed by the results of experiments.
Keywords/Search Tags:gas-solid fluidized bed, gas-liquid two-phase flow, differential pressure fluctuation signal, flow pattern identification, higher-order statistics, bispectral estimation algorithm, parallel algorithm
PDF Full Text Request
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