| 内容提要: |
To improve the accuracy of vortex flowmeter in mist annular flow of wet gas, the characteristics of two-phase vortex street were investigated and the influence of discrete droplets on the meter over-reading was analyzed. For calibrating experiments, a mist annular flow loop was developed where the discrete droplets smaller than 50 micron were generated by high-pressure micro-sprayer nozzles. The accurate gas and liquid flowrates were calibrated by the sonic nozzle standard facility and metering pump system respectively. Then, the amplitude and signal quality of the vortex street signal were investigated to analyze the effect of liquid phase on the signals. Due to the poor vortex street signal in two-phase flow, a new signal processing algorithm based on empirical mode decomposition (EMD) and Spectrum Centrobaric Correction Method (SCCM) was proposed and validated by the experiments. Lastly, the key parameter, the over-reading was analyzed by the proposed method and found that the mass loading of dispersed micron droplets can be as a main factor, which affects the gas flowrate over-reading of vortex flowmeter in mist annular flow directly. |