مهندسی دریا
Mohammad Taghi Serajian; Alireza Masjedi; Mohammad Heidarnejad; Hooshang Hasonizadeh
Abstract
In this study, experiments are carried out to determine the deviation flow into the intake in a 90º convergent bend, aiming to investigate the effect of flow characteristics on deviation flow with and without submerged vanes. The effective variables include Froude number, convergence, and submerged ...
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In this study, experiments are carried out to determine the deviation flow into the intake in a 90º convergent bend, aiming to investigate the effect of flow characteristics on deviation flow with and without submerged vanes. The effective variables include Froude number, convergence, and submerged vanes’ angle. For this research, a Rectangular channel with a 90º arc was used, which was studied using four different discharges, four different angles of submerged vanes and four degrees of convergence of the end of the channel. According to the results, the deviation flow to the intake increases by converging the laboratory flume. As the end of the flume is converged, the deviation flow is further increased. As the flume is converged (b/B) from 0 to 0.75, the deviation flow is increased from 64.9 to 81.4%, showing a 16.5% increase. Deviation flow is decreased by installing submerged vanes. A decrease in submerged vanes’ angle reduces the deviation flow. Compared to the model without a submerged vane, deviation flow is decreased by 14.9, 9.9, 6.8, and 2.3% by installing submerged vanes at angles of 25, 30, 45 and 60º, respectively. Deviation flow is also decreased by increasing the Froude number, such that it decreases by 5.3% with the increase of Froude number from 0.14 to 0.23.
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.