稠密气固两相流静电与压力信号多尺度分析

Multi-scale Resolution of Pressure Signal and Electrostatic Signal of Dense Phase Pneumatic Conveying of Coal Powder

粉体气力输送过程,由于颗粒之间及颗粒与管道之间碰撞、摩擦、分离,导致颗粒携带大量电荷。粉体颗粒荷电含有丰富的气固两相流动信息。在加压密相气力输送实验装置上,研究了静电信号和压力信号在表征气固两相流流动特性上的异同。利用Hilbert-Huang变换(HHT)对静电信号和压力信号进行了多尺度分解,并分别对分解的细节信号进行了R/S分析和能量计算。结果表明:静电信号主要表征气相与单颗粒及颗粒与颗粒之间相互作用的微尺度特性,而压力信号表征气相与固相整体之间相互作用的宏尺度特性。将静电信号和差压信号2种信息源结合,有助于认识高压气固两相流复杂的流动形态及其转变规律,可深层次揭示密相气固两相系统的动力学行为。

Experiments were performed on a pilot dense-phase pneumatic transport rig of pulverized coal, with a conveying pressure of up to 4MPa. Hilbert-Huang transform （HHT） and rescaled range analysis（R/S） were applied to analyzing the pressure signals and electrostatic fluctuation signals. The pressure signal and electrostatic signal of gas-solid two-phase flow were decomposed into intrinsic mode functions （IMFs） through the use of empirical mode decomposition （EMD）. Their Hilbert spectrums were obtained based on the EMD. R/S analysis and energy method were used to extract the characteristics of the decomposed signals. The results show that the pressure signals and electrostatic signals contain the flow information of the dense phase pneumatic conveying system of coal powder in different scales. Electrostatic signals mainly reflect the microscale characteristics of particle-particle interaction and particle-gas interaction, and however, the pressure signals not only reflect the macroscale characteristics of overall-interaction between gas and particles, but also reflect the mesoscale characteristics caused by the coupling of microscale and macroscale characteristics. Combination of the electrostatic sensor with the pressure sensor is useful for investigating the flow regime and stability of dense-phase gas-solid two phase flow.