بررسي خصوصيات جريان در سرريز جانبي چند وجهي مثلثي

چكيده انگليسي :

94 Investigation of Flow Characteristics in a Labyrinth Triangular Side Weir Mohamad Hosein Parandin M parandin@ag iut ac ir July 12 2014 Department of Water Engineering College of Agriculture Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Manouchehr Heidarpour heidar@cc iut ac ir Abstract A side weir is a hydraulic control structure used to divert flow from a main channel into a side channel when the water level in the main channel exceeds a specified limit Side weirs also known as lateral weirs are flow diversion devices widely used in irrigation as a head regulator of distributaries and escapes land drainage and urban sewage systems The geometric shapes of side weirs could be rectangular triangular and etc Also these geometric shapes would be used in plan which are known as labyrinth side weirs The studies on the subject have been generally focused on rectangular and triangular side weirs located on a straight channel However the same is not true for labyrinth side weirs In this study the hydraulic characteristics of triangular labyrinth side weirs with various length in subcritical flow were considered Discharge coefficient water surface profiles variation of specife energy three dimensional velocity distributions over the side weir variation of angle over the side weir were investigated Results show that the discharge coefficients of triangular labyrinth side weirs have much higher values than those of classical rectangular side weirs The primary reason for this may be the increased crest length The intensity of secondary motion created by lateral flow increases with increasing overflow length Discharge coefficient of the triangular labyrinth side weirs with one cycle is 1 5 2 2 times higher than rectangular side weir Discharge coefficient of the triangular labyrinth side weirs with two cycle is 1 8 2 5 times higher than rectangular side weir and discharge coefficient of the triangular labyrinth side weirs with two cycle is 1 1 1 5 times higher than triangular labyrinth side weirs with one cycle The values of the discharge coefficient Cd increase with an increase in dimensionless crest height p h1 and Froude number Fr1 values Moreover the discharge coefficient Cd increases with increasing dimensionless weir opening length L W ratio Analyzing the water surface profiles indicates that at low Froude numbers water surface profiles of rectangular side weirs is almost horizontal situation With an increase Froude number water surface profile along the side weir drop slightly at the end of upstream of the weir crest then rise quickly toward the end of downstream of the weir Generally the maximum water level is at the end of downstream of the weir The water surface profiles of triangular labyrinth side weirs along the weir crest reach a minimum level next to the end of the upstream of the weir and then water depth reaches a maximum level at the end of downstream of the weir Results show that at the upstream and downstream of the side weir which are far from the weir plan the flow could be considered to be almost horizontal and the values of vy and vz are small The results revealed that the highest values of vx that referred to the longitudinal velocity occur near the beginning of the weir while the lowest values of this component of velocity would take place close to the end of the weir The v y that implies the velocity of spill flow over the side weir increases along the crest of weir from the beginning of the weir toward the end of it The maximum of vy was observed close to the end of the weir The velocity vz shows the vertical velocity over the side weir The values of vz demonstrated that the flow moves upward near the side weir With increasing the depth the z velocity gradually decreases until the downward flow is generated at the water surface Results of variations of the flow angle showed that the flow angle is in the longitudinal direction of the main channel next to the end of the ups

پرندين، محمدحسين

بررسي خصوصيات جريان در سرريز جانبي چند وجهي مثلثي

ضريب دبي , نيم رخ سطح آب , توزيع سرعت , زاويه جريان