اثر جت و زبري نيم استوانه اي بر مشخصات پرش هيدروليكي

Influence of jet and half cylindrical roughness on hydraulic jump characteristics

ﭘﮋوﻫﺶ ﺣﺎﺿﺮ ﺟﻬﺖ ﺑﺮرﺳﯽ ﻫﻢزﻣﺎن اﺛﺮ ﺟﺖ آزاد ﻣﺴﺘﻄﯿﻠﯽ و زﺑﺮي ﻧﯿﻢاﺳﺘﻮاﻧﻪاي ﺑﺮ ﻣﺸﺨﺼﺎت ﭘﺮش ﻫﯿﺪروﻟﯿﮑﯽ اﻧﺠﺎم ﮔﺮﻓﺘﻪ اﺳﺖ. اﯾـﻦ ﭘـﮋوﻫﺶ داﺧﻞ ﯾﮏ ﻓﻠﻮم ﺑﻪ ﺷﮑﻞ ﯾﮏ ﮐﺎﻧﺎل ﻣﺴﺘﻄﯿﻠﯽ ﺑﻪ ﻃﻮل 10 ﻣﺘﺮ و ﻋﺮض 30 ﺳﺎﻧﺘﯿﻤﺘﺮ اﻧﺠﺎم ﮔﺮﻓﺖ. ﺳﭙﺲ ﺟﺖ ﺑﺎ دﺑﯽﻫﺎي 3/2 ،2/5 ،2 ﻟﯿﺘـﺮ ﺑـﺮ ﺛﺎﻧﯿـﻪ ﺑـﺎ زاوﯾﻪ ﺣﺪاﮐﺜﺮ اﺛﺮ ﺟﺎﺑﻪﺟﺎﯾﯽ اﺑﺘﺪاي ﭘﺮش و زاوﯾﻪ ﺑﺪون ﺗﻐﯿﯿﺮ اﺑﺘﺪاي ﭘﺮش ﺑﻪ اﻧﺘﻬﺎي ﭘﺮش ﻫﯿﺪروﻟﯿﮑﯽ وارد ﮔﺮدﯾﺪ.ﻧﺘﺎﯾﺞ اﯾﻦ ﭘﮋوﻫﺶ ﻧﺸﺎن ﻣﯽدﻫـﺪ ﮐـﻪ در زاوﯾﻪ ﻣﺸﺨﺼﯽ از ﺑﺮﺧﻮرد ﺟﺖ ﺑﻪ ﭘﺮش ﻫﯿﺪروﻟﯿﮑﯽ ﻫﯿﭻﮔﻮﻧﻪ ﺟﺎﺑﻪﺟﺎﯾﯽ در ﭘﺮش اﯾﺠﺎد ﻧﻤﯽﺷﻮد ﮐﻪ اﯾﻦ زاوﯾﻪ را ﺑﻪ ﻋﻨﻮان زاوﯾﻪ ﺑﯽاﺛﺮ ﻧﺎﻣﮕﺬاري ﺷﺪ و ﺑـﺎ اﻓﺰاﯾﺶ زاوﯾﻪ ﺟﺖ ﭘﺮش ﺑﻪ ﺳﻤﺖ ﺑﺎﻻ دﺳﺖ ﺣﺮﮐﺖ ﻣﯽﮐﻨﺪ و از ﯾﮏ زاوﯾﻪ ﺑﻪ ﺑﻌﺪ ﭘﺮش ﻫﯿﭻﮔﻮﻧﻪ ﺣﺮﮐﺘﯽ ﺑﻪ ﺳﻤﺖ ﺑﺎﻻ دﺳﺖ ﻧﺪارد ﮐﻪ اﯾﻦ زاوﯾﻪ ﺑﻪ ﻋﻨﻮان زاوﯾﻪ ﺣﺪاﮐﺜﺮ ﺟﺎﺑﺠﺎﯾﯽ ﻧﺎﻣﮕﺬاري ﮔﺮدﯾﺪ ﺗﻐﯿﯿﺮ در زاوﯾﻪ و دﺑﯽ ﺟﺖ ﻣﻮﺟﺐ ﮐﺎﻫﺶ ﯾﺎ اﻓﺰاﯾﺶ، ﻃﻮل ﭘﺮش، ﻋﻤﻖ ﺛﺎﻧﻮﯾﻪ اﻓﺖ اﻧـﺮژي ﻧﺴـﺒﯽ و ﻧﯿـﺮوي ﺗـ ﻨﺶ ﺑﺮﺷﯽ ﺑﺴﺘﺮ ﻣﯽﮔﺮدد اﺳﺘﻔﺎده از ﺟﺖ ﺑﺎ ﺣﺪاﮐﺜﺮ زاوﯾﻪ 145درﺟﻪ، دﺑﯽ3/2 ﻟﯿﺘﺮ ﺑﺮ ﺛﺎﻧﯿﻪ و ﮐﻤﺘﺮﯾﻦ ﻋﺪد ﻓﺮود )6/64( ﺟﺮﯾﺎن و زﺑﺮي ﻧﯿﻢ اﺳﺘﻮاﻧﻪاي ﮐﺎﻫﺶ ﺗـﺎ ﺣﺪود 32/3 درﺻﺪي ﻧﺴﺒﺖ ﻋﻤﻖ ﺛﺎﻧﻮﯾﻪ ﺑﻪ ﺣﺎﻟﺖ ﺑﺪون ﺟﺖ و ﺑﺴﺘﺮ ﺻﺎف ﮔﺮدﯾﺪ. ﺑﻪ ﮐﺎرﮔﯿﺮي ﺟﺖ ﺑﺎ زاوﯾﻪ 127 )زاوﯾﻪ ﺑﯽ اﺛﺮ( درﺟﻪ، ﺣﺪاﮐﺜﺮ ﻋـﺪد ﻓـﺮود )9/64( ﺟﺮﯾﺎن و زﺑﺮي ﻧﯿﻢ اﺳﺘﻮاﻧﻪاي ﻣﻮﺟﺐ ﮐﺎﻫﺶ ﺗﺎ 0/12 درﺻﺪ ﻧﺴﺒﺖ ﺑﻪ ﺣﺎﻟﺖ ﺑﺪون ﺟﺖ و ﺑﺴﺘﺮ ﺻﺎف ﻣﯽﺑﺎﺷﺪ. ﺑﯿﺸﺘﺮﯾﻦ ﻣﯿﺰان ﮐﺎﻫﺶ ﻃﻮل ﭘﺮش )34/7( درﺻﺪ زﻣﺎﻧﯽ رخ ﻣﯽدﻫﺪ ﮐﻪ از ﺟﺖ ﺑﺎ زاوﯾﻪ ﺣﺪاﮐﺜﺮ و دﺑﯽ3/2 ﻟﯿﺘﺮﺑﺮﺛﺎﻧﯿﻪ و در ﺷﺮاﯾﻂ ﮐﻤﺘـﺮﯾﻦ ﻋـﺪد ﻓـﺮود )6/64( ﺟﺮﯾـﺎن و ﺑﯿﺸـﺘﺮﯾﻦ اﻓـﺰاﯾﺶ درﺣﺎﻟﺖ زاوﯾﻪ 70 درﺟﻪ، ﺣﺪاﮐﺜﺮ دﺑﯽ ﺟﺖ و ﺣﺪاﮐﺜﺮ ﻋﺪد ﻓﺮود در ﺑﺴﺘﺮ ﺻﺎف 8/16 درﺻﺪ ﻣﯽﺑﺎﺷﺪ.

The present study was conducted to simultaneously investigate the effect of rectangular free jet and semi-cylindrical roughness on hydraulic jump characteristics. This study was performed inside a flume in the form of a rectangular channel 10 meters long and 30 centimeters wide. Then the jet with flows of 3/2, 2, 2/5 Liters per second with the maximum displacement effect of the beginning of the jump and the angle without changing the beginning of the jump to the end of the hydraulic jump. Take this angle as The angle was named ineffective and with the increase of the jet angle, the jump moves upwards and from one angle onwards, the jump does not move upwards. This angle was named as the maximum displacement angle. Decrease or increase, jump length, The secondary depth of the relative energy drop and shear stress force of the bed is used. The secondary was smoothed to a jetless state. Deployment The jet with an angle of 127 (inertial angle) degree, maximum landing number (9.64) flow and semi-cylindrical roughness reduces to 0.12% compared to the state without jet and smooth bed. The highest reduction in jump length (34.7%) occurs when the maximum flow angle from the jet and the flow rate is 3.2 liters per second and in the conditions of the lowest landing number (6.64) and the maximum increase in the 70 degree angle mode, the maximum jet flow an‎d the maximum landing number in a flat bed is 8.16%.