ﺑﺮرﺳﯽ ﻋﺪدي ﺗﺎﺛﯿﺮ آراﯾﺶ ﻫﻨﺪﺳﯽ ﻣﻮاﻧﻊ ﺑﺮ ﻣﯿﺰان اﺳﺘﻬﻼك اﻧﺮژي ﺟﺮﯾﺎن ﻋﺒﻮري از روي ﺷﻮت ﻫﺎي ﻣﺎﻧﻊدار

Effect of Geometric Arrangement of the Baffles on the Energy Dissipation Rate of the Baffled Chutes

در اﯾﻦ ﺗﺤﻘﯿﻖ ﺑﺎ اﺳﺘﻔﺎده از ﻧﺮم اﻓﺰار Flow-3Dﺑﻪ ﺷﺒﯿﻪﺳﺎزي ﻋﺪدي رﻓﺘﺎر ﺟﺮﯾﺎن در ﺷﻮتﻫﺎي ﻣﺎﻧﻊدار ﭘﺮداﺧﺘﻪ ﺷﺪه اﺳﺖ. ﺑﻪ ﻫﻤﯿﻦ ﻣﻨﻈﻮر اﺑﺘﺪا ﺑﺎ ﺑﻬﺮه ﮔﯿﺮي از اﻃﻼﻋﺎت ﻣﺪل آزﻣﺎﯾﺸﮕﺎﻫﯽ و ﭘﺲ از ﺗﻌﺮﯾﻒ ﺷﺮاﯾﻂ ﻣﺮزي ﻻزم، ﺻﺤﺖﺳﻨﺠﯽ ﻣﺤﺎﺳﺒﺎت ﻋﺪدي ﻣﺬﮐﻮر اﻧﺠﺎم ﭘﺬﯾﺮﻓﺖ. ﺳﭙﺲ ﺗﺎﺛﯿﺮ ﻓﺎﺻﻠﻪ ﺑﯿﻦ ردﯾﻒﻫﺎي ﻣﻮاﻧﻊ در دو ﺣﺎﻟﺖ ﻓﻮاﺻﻞ ﯾﮑﻨﻮاﺧﺖ و ﻏﯿﺮﯾﮑﻨﻮاﺧﺖ ﺑﺮ ﻣﯿﺰان اﺳﺘﻬﻼك اﻧﺮژي در ﺷﻮت ﺑﺎ ﻃﻮل ﺛﺎﺑﺖ ﻣﻮرد ﻣﻄﺎﻟﻌﻪ و ﺑﺮرﺳﯽ ﻗﺮار ﮔﺮﻓﺖ. ﻧﺘﺎﯾﺞ ﺣﺎﺻﻠﻪ ﻧﺸﺎن ﻣﯽ دﻫﺪ اﻓﺰاﯾﺶ دو ﺑﺮاﺑﺮي ﻓﻮاﺻﻞ ردﯾﻒﻫﺎي ﻣﻮاﻧﻊ در ﺣﺎﻟﺖ ﻓﻮاﺻﻞ ﯾﮑﻨﻮاﺧﺖ ﺑﯿﻦ ردﯾﻒﻫﺎ، ﮐﺎﻫﺶ ﻧﺴﺒﺘﺎْ ﮐﻢ )ﺣﺪود 17/5 درﺻﺪ( ﻣﯿﺰان اﺳﺘﻬﻼك اﻧﺮژي را در ﭘﯽ دارد ﺑﺎ اﯾﻦ وﺟﻮد اﻓﺰاﯾﺶ ﻓﻮاﺻﻞ ردﯾﻒﻫﺎ ﻣﻨﺠﺮ ﺑﻪ ﺑﻬﺒﻮد ﻋﻤﻠﮑﺮد ﻫﺮ ﮐﺪام از ردﯾﻒﻫﺎ ﻣﯽ ﮔﺮدد. در ﺑﺮرﺳﯽ دﯾﮕﺮ ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﭼﻨﺎﻧﭽﻪ ﻓﺎﺻﻠﻪي ردﯾﻒﻫﺎ در ﻃﻮل ﺷﻮت ﻏﯿﺮﯾﮑﻨﻮاﺧﺖ ﺑﺎﺷﺪ و در راﺳﺘﺎي ﻃﻮﻟﯽ ﺷﻮت ﺑﻄﻮر ﺗﺼﺎﻋﺪي اﻓﺰاﯾﺶ ﯾﺎﺑﺪ، ﺑﺎ وﺟﻮد ﮐﺎﻫﺶ ﺗﻌﺪاد ردﯾﻒ ﻣﻮاﻧﻊ در ﻃﻮل ﮐﻞ ﺷﻮت ﻫﻤﭽﻨﺎن اﺳﺘﻬﻼك اﻧﺮژي ﻧﺴﺒﺖ ﺑﻪ ﻣﺪل ﻣﺘﻨﺎﻇﺮ ﺑﺎ ﻓﻮاﺻﻞ ﯾﮑﻨﻮاﺧﺖ ردﯾﻒﻫﺎ اﻓﺰاﯾﺶ ﺧﻮاﻫﺪ ﯾﺎﻓﺖ. ﻋﻼوه ﺑﺮ ﺑﺮرﺳﯽ اﺛﺮ ﻓﻮاﺻﻞ ﻣﻮاﻧﻊ در راﺳﺘﺎي ﻃﻮﻟﯽ ﺷﻮت، ﺗﺎﺛﯿﺮ ﺗﻌﺪاد ﻣﻮاﻧﻊ در ﻫﺮ ردﯾﻒ )در راﺳﺘﺎي ﻋﺮﺿﯽ ﺷﻮت( ﺑﺮ ﻣﯿﺰان اﺳﺘﻬﻼك اﻧﺮژ ي ﻧﯿﺰ ﻣﻮرد ﺑﺮرﺳﯽ ﻗﺮار ﮔﺮﻓﺖ در اﯾﻦ ﺑﺮرﺳﯽ درﺻﺪ اﻧﺴﺪاد ﺛﺎﺑﺖ در ﻧﻈﺮ ﮔﺮﻓﺘﻪ ﺷﺪ ﺑﻨﺎﺑﺮاﯾﻦ اﻓﺰاﯾﺶ ﺗﻌﺪاد ﺑﻠﻮكﻫﺎي ﻫﺮ ردﯾﻒ ﺑﺎ ﮐﺎﻫﺶ ﻋﺮض ﻫﺮ ﺑﻠﻮك ﻫﻤﺮاه اﺳﺖ. ﻧﺘﺎﯾﺞ اﯾﻦ ﺑﺮرﺳﯽ ﻧﺸﺎن داد ﮐﻪ اﻓﺰاﯾﺶ ﺗﻌﺪاد ﻣﻮاﻧﻊ در ﻋﺮض ﺷﻮت، ﺗﺎﺛﯿﺮ ﭼﻨﺪاﻧﯽ )ﺗﻐﯿﯿﺮات ﮐﻤﺘﺮ از 2درﺻﺪ ﺑﺮ ﻣﯿﺰان اﺳﺘﻬﻼك اﻧﺮژي ﻧﺪارد.

Baffled chutes are energy dissipation structures that are used in chutes and water conveyance and distribution structures. Energy dissipation in these structures occurs by the flow collision with the upstream side of the installed baffles on the chute. In the present study, the Flow-3D numerical model was used to simulate flow behavior on the baffled chutes. For this purpose, the numerical calculations were validated using the available experimental data upon introduction of the boundary conditions. Then, the effect of the distance between the baffle rows on the energy dissipation rate of the baffled chutes was studied. The results showed that for a fixed distance between the baffles according to the USBR recommendation, by increasing the distance between the baffle rows (decreased number of baffles), the flow collision to the baffles decreased and consequently, energy dissipation rate decreased. In addition, by continuous increase of the distance between the baffle rows on the chute, the energy dissipation rate on the chute increased (even with smaller number of baffles). In the present study, the effect of increasing the number of baffles on the chute width was studied by keeping a constant blockage. The results showed that by increasing the number of baffles on the chute width (for a constant blockage), the energy dissipation rate did not change significantly. However, the blockage magnitude in the chute width influenced the energy dissipation rate of the chute.