噴流干渉時の乱流構造に関する実験的研究 -双対噴流の乱流構造-

Abstract

For establishment of a reasonable hydraulic design of multi-diffuser by which various wastewaters such as sewage or warmed water can be efficiently diffused in river or sea, an experimen-tal investigation on the turbulent structure of two-dimensional dual-jet whose two nozzles wereset in parallel has been performed. By systematically varying the ratio of flow quantity of eachjet and the space between both nozzles, the mean velocity distribution and the turbulence charac-teristics of the dual jet have been investigated through hot-film measurements and visual obser-vations.Since the flow axes of dual jet were attracted and then merged each other, the flow fieldcould be divided into three subregions: (1) two-single-jet region (before mergence), (2) one-single-jetregion (after mergence) and (3) transition region between (1) and (2). The turbulent structure ofeach subregion could be described fairly well by a simple model in which two Gaussian profileswere combined under the conservation law of momentum flux. A noticeable fact has been alsoobtained from the characteristics of intermittency factor, macro-scale of turbulence and spectraldistribution that a coherent motion, so-called 'puff phenomenon', appeared near the edge of potentialcore of both single- and dual-jets.