CLARIFICATION OF SPECTRAL STRUCTURE AND PROPAGATION MECHANISM OF AN INTERMITTENT TURBULENCE AND ITS CONTROL

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1. Experiments and analysis of intermittent turbulenceIntermittent turbulence which occurred in an intermittent oscillatory pipe flow was measured and fluctuations in velocity was analyzed. Turbulent regions are convected downstream and the transition occurred as a result of the passage of the leading interface of a turbulent region. We detected large and medium scale eddies generated near the leading front. The eddies must play a major role in the transition.2. Theory and applications of a random process and a random fieldThe theory of the number of degrees of freedom (NDF) of a random process on which the project is based was investigated. The relation between the NDF and Fisher information was clarified. The results are as follows ; (a)The first NDF is nothing but the Fisher information about mean of the random process. (b)For the AR process, the 2nd NDF is equal to the Fisher information about the variance of the random process.It was proved that the NDF can explain the significance of the approximating the dimension of the signal space to 2WT.We deduced correlation areas and correlation lengths of a random field from the idea of the NDF.These are important characteristics of the random field. A visualized turbulent field were analyzed by using the correlation areas and the correlation lengths.3. Experimental study of combustionIn order to study the effect of combustion on the turbulence, we performed some experiments on combustion.