【作者】 陈永国； 田子平； 缪正清；

【Author】 CHEN Yong-guo, TIAN Zi-ping, MIAO Zheng-qing (School of Mechanical and Power Engineering, Shanghai JiaoTong University, Shanghai 200240, China)

【机构】 上海交通大学机械与动力工程学院；

【摘要】 循环流化床压力波动信号是研究床内流体动力学的重要线索.本文在150 mm×150mm×2000 mm的循环流化床上进行试验,测量了不同工况下床壁的静压力波动信号.对获得的压力波动信号进行连续小波变换,利用小波变换模极大计算所得的全局分解函数来计算具有相同正则性的点集的分形维数.所取得的小波多分形谱能够很好地描述压力波动信号的几何特征和局部尺度行为.本文提取的最大多分形谱、最大多分形谱对应的Lipschitz指数、Lipschitz指数宽度三个特征对描述循环流化床中的流态转变,具有很好的作用.更多还原

【Abstract】 The pressure fluctuations are the important keys to study the gas-solid .flow mechanism in circulating fluidized beds. In this study, the experiments are carried out in the lab-scale circulating fluidized bed with three dimensional sizes: 150 mm×150 mm×2000 mm. The pressure fluctuations under diverse operating conditions are measured. Continuous wavelet transform is put on these pressure signals. Then the wavelet local maxima modulus based method is used to obtain the wavelet multifractal spectras, which can describe the geometrical characteristics and local scale behaviors of the pressure signals. The maximal D associated with the Lipschitz a corresponding to the maximal D, and the width of the Lipschitz a are utilized to denote the fluidization regime transition. This method can characterize the three flow regime transitions from the static bed to bubbling fluidization, from bubbling fluidization to turbulent fluidization and from turbulent fluidization to fast fluidization.更多还原