بررﺳﯽ آزﻣﺎﯾﺸﮕﺎﻫﯽ اﺳﺘﻬﻼك اﻧﺮژي ﺟﺮﯾﺎن ﻋﺒﻮري از ﺳﺮرﯾﺰﻫﺎي ﭘﻠﮑﺎﻧﯽ ﻫﻤﺮاه ﺑﺎ اﻟﺤﺎق اﻟﻤﺎن ﻫﺎﯾﯽ روي ﭘﻠﻪ

Experimental Study of Energy Dissipation over Stepped Spillway with Appendance Elements on the Steps

ﭘﻠﻪﻫﺎ در ﺳﺮرﯾﺰ ﭘﻠﮑﺎﻧﯽ ﺑﺎ اﯾﺠﺎد ﯾﮏ ﺑﺴﺘﺮ زﺑﺮ ﻣﺼﻨﻮﻋﯽ، اﻧﺮژي ﺟﺮﯾﺎن را ﺑﯿﺶ از اﻧﻮاع دﯾﮕﺮ ﺳﺮرﯾﺰﻫﺎ ﻣﺴﺘﻬﻠﮏ ﻣﯽﮐﻨﻨـﺪ . ﺑـﺎ اﻓـﺰاﯾﺶ زﺑـﺮي، اﻧـﺮژي ﺟﺮﯾﺎن ﻋﺒﻮري از روي ﺳﺮرﯾﺰ ﺑﻪﺻﻮرت ﯾﮑﻨﻮاﺧﺖ و ﭘﯿﻮﺳﺘﻪ ﭘﺮاﮐﻨﺪه ﻣﯽﺷﻮد. ﻫﺪف از ﺗﺤﻘﯿﻖ ﺣﺎﺿﺮ، ﺑﺮرﺳﯽ اﻓﺰودن اﻟﻤﺎنﻫﺎﯾﯽ ﺑﺮ روي ﭘﻠﻪﻫﺎ و ﺗﺄﺛﯿﺮ آن ﺑﺮ ﺗﻐﯿﯿﺮات اﻟﮕﻮي ﺟﺮﯾﺎن، ﻧﻘﻄﻪ ﺷﺮوع ﻫﻮادﻫﯽ، ﻣﯿﺰان اﺳﺘﻬﻼك اﻧﺮژي و ﺿﺮﯾﺐ زﺑﺮي دارﺳﯽ ﻣﯽﺑﺎﺷﺪ. آزﻣﺎﯾﺸﺎت ﺑﺮ روي ﻣﺪل ﻓﯿﺰﯾﮑﯽ ﺳﺮرﯾﺰ ﭘﻠﮑﺎﻧﯽ و ﺑـﺎ اﻟﺤﺎق اﻟﻤﺎنﻫﺎﯾﯽ ﺑﺮ روي ﭘﻠﻪ در آراﯾﺶﻫﺎي ﻣﺨﺘﻠﻒ و ﺑﻪﺻﻮرت ﭘﯿﻮﺳﺘﻪ و ﻫﻤﺮاه ﺑﺎ ﺷﮑﺎف اﻧﺠﺎم ﮔﺮدﯾﺪ و ﻧﺘﺎﯾﺞ ﺑﺎ ﺳﺮرﯾﺰ ﭘﻠﮑﺎﻧﯽ ﺳﺎده ﻣﻮرد ﻣﻘﺎﯾﺴـﻪ ﻗـﺮار ﮔﺮﻓﺖ. ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﮐﻪ اﯾﺠﺎد ﻣﺎﻧﻊ ﺑﺮ روي ﭘﻠﻪﻫﺎ ﺑﺎﻋﺚ اﯾﺠﺎد ﺑﺮﺧﯽ ﺗﻼﻃﻢ و ﻧﻮﺳﺎﻧﺎت ﺑﺮ روي ﺳﻄﺢ ﺟﺮﯾﺎن در ﻣﺮﮐﺰ و ﮐﻨﺎرهﻫﺎي ﭘﻠﻪ ﻣﯽﺷﻮد. اﯾﻦ اﻣـﺮ ﺑﺎﻋﺚ اﺧﺘﻼط ﺑﯿﺸﺘﺮ آب و ﻫﻮا و اﻧﺘﻘﺎل ﻣﺤﻞ ﻧﻘﻄﻪ ﺷﺮوع ﻫﻮادﻫﯽ ﺑﻪ ﺑﺎﻻدﺳﺖ ﺳﺮرﯾﺰ ﭘﻠﮑﺎﻧﯽ ﻣﯽﺷﻮد. رژﯾﻢ ﺟﺮﯾﺎن اﻧﺘﻘﺎﻟﯽ و ﻏﯿﺮ رﯾﺰﺷﯽ ﺑﺮ روي ﻣﺪلﻫﺎي ﺳﺮرﯾﺰ ﭘﻠﮑﺎﻧﯽ ﻫﻤﺮاه ﺑﺎ ﻣﺎﻧﻊ در دﺑﯽﻫﺎي ﭘﺎﯾﯿﻦﺗﺮي ﻧﺴﺒﺖ ﺑﻪ ﺳﺮرﯾﺰ ﭘﻠﮑﺎﻧﯽ ﺳﺎده اﺗﻔﺎق ﻣﯽاﻓﺘﺪ. ﺗﻐﯿﯿﺮ رژﯾﻢ ﺟﺮﯾﺎن ﺑﺮ روي ﺳﺮرﯾﺰ ﭘﻠﮑـﺎﻧﯽ ﻫﻤـﺮاه ﺑـﺎ ﻣـﺎﻧﻊ ﺷﮑﺎﻓﺪار دﯾﺮﺗﺮ از ﺣﺎﻟﺖ ﭘﯿﻮﺳﺘﻪ روي ﻣﯽدﻫﺪ. ﻫﻤﭽﻨﯿﻦ ﻣﻮاﻧﻊ روي ﭘﻠﻪ ﺗﺄﺛﯿﺮي ﺑﺮ روي ﻣﯿﺰان اﺳﺘﻬﻼك اﻧﺮژي ﺟﺮﯾﺎن و ﺿﺮﯾﺐ زﺑﺮي ﻧﺪارﻧﺪ وﻟﯽ ﺑـﺎ اﯾﺠـﺎد ﺷﮑﺎف ﺑﺮ روي ﻣﻮاﻧﻊ ﻋﻤﻠﮑﺮد آنﻫﺎ ﺑﻬﺘﺮ ﺷﺪه و ﻣﯿﺰان اﺳﺘﻬﻼك اﻧﺮژي و ﺿﺮﯾﺐ زﺑﺮي دارﺳﯽ ﺑﻪﻃﻮر ﻣﺘﻮﺳﻂ ﺑﻪ ﺗﺮﺗﯿﺐ 7/33 و 8 درﺻﺪ ﻧﺴﺒﺖ ﺑﻪ ﺳـﺮرﯾﺰ ﭘﻠﮑﺎﻧﯽ ﺳﺎده اﻓﺰاﯾﺶ ﻣﯽﯾﺎﺑﺪ.

Steps in the stepped spillway by creating an artificial roughening bed, dissipate the flow of energy more than other types of spillways. An increase of roughness leads to a uniform and continuous distribution energy of the flow over the spillway. The present study deals with experimental study regarding the appendance elements on the steps and its impact on the variation of the flow pattern, inception point, energy dissipation and Darcy roughness coefficient. Experiments were performed on a physical model, with appendance elements on the steps in different configurations and type (height and notch), and the results were compared with flat stepped spillway. The results showed that the appendance elements on the steps causes some the instabilities and turbulence on the center axis and sides of the steps, which causes the inception point to be moved upstream of the stepped spillway. A nappe and transition flow regimes on stepped spillways with appendance elements occur at lower discharges than flat stepped spillway. With notched, the change of the flow regime on the stepped spillway occurs later than in the height state. Also, the appendance elements on the steps have no effect on the energy dissipation and Darcy roughness coefficient. However, with notched on the appendance elements, their performance is improves and the amount of energy dissipation and Darcy roughness coefficient increases 7.33% and 8% compared to flat stepped spillway, respectively