乱流自由噴流における乱流間欠性現象の研究

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システム工学部門の研究現況Study on the structure and dynamics of turbulent intermittency which has been carried out in our labolatory is reviewed. Turbulent intermittency functions were derived from hot-wire signals using a turbulent/non-turbulent decision processing, and used to obtain the zone average velocity and spectrum of intermittency. Walsh spectral analysis reveals that the large scale motions have many length scales longer than several-times the velocity half width. By using a 7-channel hot-wire array, conditional ensemble averaged patterns of turbulent bulges were assessed. An interesting phenomenon that the tip of turbulent bulge flowed slower than the co flowing free stream is attributed to the large-scale eddy motions in the intermittent region. And a novel method to measure the conditional turbulent zone averages by using laser doppler anemometer with selective seeding was developed and compared experimentally with the method based on hot-wire signals.
1992-03-31