循环流化床颗粒浓度波动信号多重分形测度分析

由于循环流化床气－固两相流动规律相当复杂，使得至今对其流动规律的认知仍不足以直接用于循环流床的工业设计与放大。近十多年来，确定性混沌理论已被用于循环流化床动力学特性的研究，与其密切相关的分形理论也被用于流化床流动特性的研究。然而，这些研究所用均是采用单分形理论，而单分形理论对解释循环流化床复杂的非线性气－固流动行为显得能力不足。为了探讨循环流化床内颗粒流体系统非线性、非均匀性和混沌特性机理。本文引入不同测试多重分形分析的方法，用小波变换模极大值与多重分形测度分析方法相结合，检测循环流化床颗粒浓度波动信号奇异性并得出多重分形奇异谱。结果表明循环流化床颗粒浓度波动信号具有明显的多重分形特性。小波变换多重分形方法可以用来描述床内颗粒流动特性，为探讨循环流化床颗粒流体系统非均匀机制提出了一种新的方法。

Multifractal Measure Analysis of Solid Hold-up Fluctuation Signal in Circulating Fluidized Bed

In the past decades, the chaos analysis method and fractal analysis technique based on the mono-fractal theory were used to clarify the dynamic behavior of circulating fluidized bed (CFB). However, the mono-fractal theory is restricted to explain such a complex nonliearity behavior as gas-solid flow in CFB. In order to understand the intrinsic formalism of heterogeneity, nonlinearity and chaotic behavior of particle-fluid system in circulating fluidized bed, a new method was presented to describe the heterogeneity formalism of the particle-fluid system in this paper. Based on the wavelet transform modulus maxima method, we performed multifractal measure analysis of solid hold-up fluctuation signal in CFB riser and got the multifractal singularity spectra of signals. The results showed that solid hold-up fluctuation signal in CFB had the multifractal characteristic. The motion behavior of particles in CFB can be characterized by the singularity spectra and singularity exponents.