Investigation of the labyrinth rectangular weirs efficiency with equal and unequal congresses in plan

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: Investigation of the labyrinth rectangular weirs efficiency with equal and unequal congresses in plan

ارائه دهنده: Provider: Mohammad Hosein Masoudi

اساتید راهنما: Supervisors: Dr. Jalal Sadeghian

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: Dr. Bahram Rezaei - Dr. Morteza Shokri

زمان و تاریخ ارائه: Time and date of presentation: 20-10-2021

مکان ارائه: Place of presentation: Online

چکیده: Abstract: Spillways are one of the most important hydraulic structures. Spillways must have sufficient capacity, efficiency and safety in the passage of floods, and in addition must have economic justification. One of the effective and economical solutions to increase the discharge capacity within a certain width of spillways is to use labyrinth spillways. Parameters affecting the amount of spillways capacity include the relative height of the water upstream, the shape of the crest and the length of the crest. Among the mentioned parameters, the length of the spillways has the most important effect on the discharge capacity. The purpose of the labyrinth spillways is to increase the length of the spillways crest by nonlinearizing its shape in the plan. This increases the efficiency and increases the flow rate. In labyrinth spillways, the overlap of the water blades and the subsequent compression of the flow during the overflow reduces the efficiency and discharge coefficient of the overflow. In this study, in order to reduce the interference of water blades, rectangular labyrinth spillways with unequal congress lengths in two modes A and B and in 5 cycles with the same effective length and height were studied and compared in the hydraulic laboratory of Bu-Ali Sina University Are located. The first case consists of 5 labyrinth spillways with different congress lengths, so that the closer we get to the spillway center, the longer the middle congresses increase, and the second case consists of 5 labyrinth spillways with different congressional lengths. As we get closer to the center of the spillway, the length of the middle congresses decreases, and the highest congresses in this case are the initial and final congresses. The results of these studies show that in all labyrinth spillways with dissimilar congress lengths, the value of C decreases with increasing Ht/P ratio. According to the results of this study, in general, the efficiency and discharge coefficient of rectangular labyrinth spillways of mode A is better than mode B and the reduction of the impact length of water blades up to 25% compared to labyrinth spillways. Equals with the same length of congresses increase the efficiency and improve the discharge coefficient of labyrinth spillways and reduce the impact length of water blades by more than 25% of the spillways performance out of the congressional mode and reduce the efficiency and the discharge coefficient spillways. Also, in one tested model of the first case, the overflow discharge coefficient has increased by 40.7% compared to the overflow of congresses with the same length of congresses

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