Chaotic Analysis Method And Its Application To Pressure Fluctuations In Gas-Solid Fluidized Beds

To apply chaos theory scientifically and systematically is a great task in the further development of the fluidization technology. At present, in the chaotic research of the fluidized bed, many factors such as objectivity and validity of the adopted method and the influence of the noise seriously disturb the chaotic judgement of the fluidization system so that many non-essential and different research conclusions are obtained. To deal with the deficiency, which exist in me present chaotic research on the fluidized bed, the chaotic analysis method is studied, and the nature and the characteristic of the chaotic motion of the fluidized bed are studied.First, the calculation of the correlation dimension of the chaotic analysis method is studied. The more efficient algorithm for calculating the correlation dimension from single variable time series is proposed. This optimized algorithm can save the run-time by about six times to ten times, which provides convenience for chaotic research. Then, the nature of the influence of the auto-correlation in the time series on the calculation of the correlation dimension is studied from the space geometric meaning, which is expressed by correlation integral function. Thereby the importance and feasibility of removing this influence is pointed out from the theoretical views. This contributes to correct extraction of the chaotic characteristic parameters of the system. More important is that the improved derivative reconstruction method is put forward. This method can efficiently overcome thepractical application difficult problems of the original Packard derivative reconstruction method so that it can be applied to chaotic research of the actual system. The proposal improved derivative reconstruction method is significant to the practical application of the chaotic analysis method.On the basis of the above work, by the frequency domain analysis method it is found that the frequency characteristic of the main body motion(slug motion and cluster motion) in the slugging fluidized bed and in the circulating fluidized bed is different from other fluctuation signals. So the messages of the main body motion can be extracted from the frequency domain to do chaotic analysis. The chaotic research on the signal of the main body motion and on the whole fluctuation signal(filtered the high frequency measure noise) shows that both the component of the chaotic motion and the component of the stochastic motion exist in the pressure fluctuation in the slugging fluidized bed and in the circulating fluidized bed. Thus the chaotic signal in the beds is with the strong noise, which is formed from some inherent stochastic signals in the beds. The existence of the strong noise restricts the chaotic research on the fluidized bed. So some measures have to be taken to remove the influence of the inherent stochastic component in the bed, otherwise the characteristics of the chaotic motion in the bed can not be extracted correctly. Simultaneously, it is found that the main body motion(slug motion and cluster motion) in the slugging fluidized bed and in the circulating fluidized bed has high dimensional chaotic characteristic. Thus the time-delay reconstruction method is not suitable for revealing this kind of chaotic characteristic.By the Lyapunov exponent analysis, chaotic characteristics of the traditional fluidized bed and the circulating fluidized bed are further studied. It is showed that chaotic characteristics of the slug motion or cluster motion are disturbed by other signals in the beds. It is further verified that the chaos hi the beds is chaotic motion in the strong noise background. The chaotic characteristic parameter桳yapunov dimension of the slug behavior in the slugging fluidized bed have a clear change trend in "W" shape with the gas velocity increasing. The two low points of the "W" shape curve suggest the transition of the state of the slug motion. Chaotic parametersof cluster motion in the middle part of the circulating fluidized bed first increase, and then decrease wit...