مهندسی دریا
Mohammad Hosein Noralah Dezfouli; amir abas kamanbedast; Alireza Masjedi; Mohammad Heidarnejad; Mohammad Hosein Purmohammadi
Abstract
One of the measures to control the hydraulic jump at the downstream of hydraulic structures and to provide required sequent depth is to use a stilling basin with sudden contraction. Previous studies have shown that in this basin the jump length increases compare to the classical jump. On the other hand, ...
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One of the measures to control the hydraulic jump at the downstream of hydraulic structures and to provide required sequent depth is to use a stilling basin with sudden contraction. Previous studies have shown that in this basin the jump length increases compare to the classical jump. On the other hand, it has been shown that roughening the bed is a measure that can be used to decrease the jump length. Therefore, it can bring a question that by roughening the bed of sudden contraction stilling basin how much can decrease the jump length? Therefore, in this study the effect of roughness on jump length at the mentioned stilling basin has been investigated. The tests have performed in a flume of 12-meter-long, 0.8-meter-wide and 0.7-meter height. The contraction ratio was 0.33 and the Froude number ranged between 2 to 10. The results have shown that the roughness can decrease the jump length up to 31% compare to the classic jump and can decrease up to 12% compare to the smooth bed of sudden contraction stilling basin. The jump length is equal to the USBR type II. It was found that the roughness can decrease the roller jump up to 20 percent compare to the sudden contraction of smooth bed.