两相流流量测量中的梯度相关法研究

On the Gradient Correlation Method for Two-phase Flow Rate Measurement

梯度相关方法克服了渡越时间相关方法的缺点,对两相流流量的测量具有重要的理论和应用价值。本文设计了阵列式电容传感器,信号测量与组合电路,建立了梯度相关模型和信号采集与处理系统。通过在两相流模拟实验装置上的试验研究,获得了时间自相关、互相关、协方差、空间相关等一组函数曲线。分析表明,设计的传感器和测量系统能有效地检测和处理梯度相关信号,本方法可用来直接测量两相流中分离相的质量流量和速度。

The gradient correlation method for non-intrusive velocity and flow rate measurement in two-phase flow is investigated. The true flow rates and mean velocities can be measured by evaluating slope of the cross-covariance function of the signals of appropriately designed overlapping sensors. The array capacitance sensor consisted of four pair electrodes and a measuring circuit consisted of high frequency generator, impedance-voltage converter, phase-sensitive detector, low-pass filter and amplifier are designed. A complex circuit which produces spatial correlation signal is also designed. A theoretical model of gradient correlation method is derived. By experimental results~ a series of curves of the auto-correlation, cross-correlation, crosscovariance function of time and spatial cross-correlation function have been obtained.The analyses indicate that the array capacitance sensor and measuring circuit can effectively detect the gradient correlation signal. This approach makes it possible to measure the velocity and mass flow rate in pneumatic conveyers.