نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشجوی دکتری سازه‌های آبی، گروه علوم و مهندسی آب، دانشگاه آزاد اسلامی واحد علوم و تحقیقات، تهران، ایران
2 استادیار، عضو هیئت علمی گروه علوم و مهندسی آب، دانشگاه آزاد اسلامی واحد علوم و تحقیقات، تهران، ایران
3 استاد، عضو هیئت علمی گروه علوم و مهندسی آب، دانشگاه آزاد اسلامی واحد علوم و تحقیقات، تهران، ایران
چکیده
کلیدواژه‌ها
عنوان مقاله [English]
نویسندگان [English]
Stepped chute flows are characterized by intense turbulence and strong aeration, but in most studies the turbulence characteristics are not investigated thoroughly. In this study, a highly turbulent air-water flow skimming down a large-size stepped chute has been investigated systematically. An experimental study of detailed air-water flow characteristic measurements was established for different types of flow regimes on a stepped chute (θ = 21.8º, h=0.04m, l=0.10m) model to investigate the location and the flow depth at inception point of air entrainment and velocity profiles distributions. Detailed velocity and turbulence intensity measurements in flow direction were performed by use of a phase detection conductivity probe which had been designed, developed and calibrated before. The results showed that the turbulence characteristics varied in different regions. The study showed further that 1- the turbulence intensity increased rapidly close to the step bottom at the viscous sub layer and maximized at intermediate region (0.4≤ y/dc ≤ 0.5) then decreased gradually in the upper region. 2- The vertical distribution of the velocity in flow direction followed-up a power law and the velocity reached to its maximum value, near the flow’s free surface. 3- The high turbulence levels in the intermediate region of the flow depth were caused by the continuous deformations and modification of the air-water interfacial structure.
کلیدواژه‌ها [English]
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