Research On Correlation Velocity Measurement Of Gas-solid Two-phase Flow With Capacitance Sensor

The parameters of gas-solid two-phase flow mainly include the solid particle velocity, concentration, and mass flow. The flow rate of solid particles which reflects the flow conditions of gas-solid flow is an important parameter. Detection of gas-solid flow rate for two-phase flow is important for industrial safety, economic and efficient operation.The combination of the capacitive sensor and the related measurement techniques provide a solution for gas-solid flow velocity measurements. With the advances in microelectronics technology, digital signal processor computing enhancements, it is possible to design fast response, high-precision real-time speed measurement systems. In this paper, Correlation algorithm is deeply studied, and the speed signals of capacitance of two-phase flow are analyzed. The signal detection circuit of capacitive and the acquisition system are designed, and ultimately completing the real-time measurement of gas-solid flow of solid.The main works are as follows:(1) The capacitive speed sensor is analyzed. The structure and size of the sensor are determined, and capacitive parallel speed sensor is designed.(2) A sensing circuit of capacitive sensor was designed. By experimental results from the simulation, every parts of circuit are determined. Experimental results show that the circuit can realize capacitance signal demodulation, filtering, amplification and the measurement of capacitive signal without distortion;(3) Common speed algorithms are analyzed and cross-correlation algorithm is deeply studied. And some measures are done to improve the accuracy and real-time of correlation algorithm. The fast correlation velocimetry algorithm, denoising, determined. Characteristics and application environment of the FIR, IIR digital filters are analyzed. IIR filter for the upstream and downstream signal is designed and FIR filter for cross-correlation array is designed.(4) Signal spectrum analysis is implemented and cutoff frequency of the filter is determined. Characteristics and application environment of the FIR, IIR digital filters are analyzed. IIR filter for the upstream and downstream signal is designed and FIR filter for cross-correlation array is designed.(5) The TMS320C6713is the digital processing unit and the display and communication are added to the system. Signal acquisition, filtering, computing and display are programmed in the CCS6000environment and gas-solid flow velocity measurements are realized.(6) A Labview-based velocimetry experimental platform is built, and upstream and downstream signals display, speed display, data storage and other functions are realized. Test and debug are implemented for system. By theoretical analysis of experimental data analysis, the optimal sampling frequency and sampling points are determined. Experimental verification for the filter interpolation method is implemented and speed value is corrected according to the measured velocity data.