Study On Parameter Measurement Method Of Gas-liquid Two-phase Flow In Small Channel Based On Photodiode Array Sensor And Differential Pressure Sensor

Gas-liquid two-phase flow widely exists in the petroleum,chemical and other industrial processes.Miniaturization has become an important development trend of industrial equipment,and the parameter measurement of gas-liquid two-phase flow in small channels has become one of the most attractive research topics in the two-phase flow field.However,parameter measurement technologies of gas-liquid two-phase flow in small channels are still in the development stage,and the measurement methods are limited.Therefore,research on parameter measurement of gas-liquid two-phase flow in small channels is of significant academic value and engineering application prospect.This thesis aims to implement the parameter measurement of gas-liquid two-phase flow system in small channels.Combining a differential pressure sensor and a photodiode array sensor,methods on flow regime identification and void fraction measurement of gas-liquid two-phase flow in small channels are investigated.The main work and innovations of this thesis are listed as follows:1.Based on the photodiode array sensor and the differential pressure sensor,a parameter measurement setup of gas-liquid two-phase flow in small channels is developed.A differential pressure measurement system applied to small channel is designed;the existing photodiode array sensor is optimized;and experiments of the gas-liquid two-phase flow are carried out in horizontal small channels with inner diameter of 2.12mm,3.01mm and 4.03mm,respectively.2.A flow regime identification method based on information fusion technology is proposed.Firstly,the optical signal and the differential pressure signal of different flow regimes are analyzed,and two corresponding signal features are extracted to form two feature vectors,respectively.Secondly,a flow regime identification model based on the optical signal is developed with the least squares support vector machine(LS-SVM)method,and another flow regime identification model based on the differential pressure signal is developed with the same method.Finally,the two kinds of identification results are fused by the D-S evidence theory to obtain the final flow regime identification results.Experimental results show that the identification accuracies of four typical flow regimes(bubble flow,slug flow,wavy flow and annular flow)in the mentioned three channels are all above 91%,which indicate that the proposed method based on information fusion technology is effective and has higher identification accuracy than the method based on the signal of a single sensor.3.With the optical signal,a void fraction measurement method of gas-liquid two-phase flow in small channels based on the flow regime is proposed.Firstly,the void fraction measurement model of each flow regime is developed with the optical signal and the LS-SVM method.Secondly,four flow regimes are identified with the proposed flow regime identification method and then the void fraction is obtained with the corresponding void fraction measurement models and the optical signal.The experimental results show that the proposed void fraction measurement method is effective and the maximum absolute errors are all less than 8%.In this thesis,combining the differential pressure sensor and the optimized photodiode array sensor,the flow regime identification and the void fraction measurement of gas-liquid two-phase flow in small channels under the framework of information fusion are implemented,which can provide a good reference for parameter measurement of gas-liquid two-phase flow in small channels.