بررسی اثر جت، زبری نیم استوانه‌ای و شیب معکوس بر پرش هیدرولیکی

نوع مقاله : مقاله کامل علمی پژوهشی

نویسندگان

1 استادیار گروه مهندسی آب دانشگاه بیرجند

2 کارشناسی ارشد سازه‌های آبی، گروه علوم و مهندسی آب، دانشکده کشاورزی، دانشگاه بیرجند.

چکیده

سابقه و هدف: ﺗﺸﮑﯿﻞ ﭘﺮش در ﺣﻮﺿﭽﻪ ﻫﺎی آراﻣﺶ ﻧﻘﺶ ﻣﺆﺛﺮی در اﺳﺘﻬﻼک اﻧﺮژی ﺟﺮﯾﺎن در ﭘﺎﯾﺎب ﺳﺎزه ﻫﺎی آﺑﯽ اﯾﻔﺎ ﻣﯽ ﮐﻨﺪ. ﭘﺮش ﻫﯿﺪروﻟﯿﮑﯽ از ﻧﻮع ﺟﺮﯾﺎن ﻫﺎی ﻣﺘﻐﯿﺮ ﺳﺮﯾﻊ اﺳﺖ ﮐﻪ در ﺻﻮرت ﻣﻨﺎﺳﺐ ﺑﻮدن ﺷﺮاﯾﻂ ﮐﺎﻧﺎل در ﭘﺎﯾﯿﻦ دﺳﺖ ﺟﺮﯾﺎن از ﺣﺎﻟﺖ ﻓﻮق ﺑﺤﺮاﻧﯽ ﺑﻪ زﯾﺮﺑﺤﺮاﻧﯽ ﺗﻐﯿﯿﺮ ﻣﯽ ﯾﺎﺑﺪ. در اﯾﻦ ﭘﮋوﻫﺶ ﺷﯿﻮه ﺟﺪﯾﺪی ﺑﻪ ﻣﻨﻈﻮر ﮐﺎﻫﺶ اﻋﻤﺎق ﻣﺰدوج و ﻃﻮل ﭘﺮش ﭘﯿﺸﻨﻬﺎد ﺷﺪه اﺳﺖ ﮐﻪ در آن از وﯾﮋﮔﯽﻫﺎی ﯾﮏ ﺟﺖ ﻣﺴﺘﻄﯿﻠﯽ آزاد ﺳﺮﯾﻊ و زﺑﺮی ﮐﻒ ﺑﺮای ﺗﺄﺛﯿﺮ ﮔﺬاری ﺑﺮ ﺧﺼﻮﺻﯿﺎت ﭘﺮش اﺳﺘﻔﺎده ﮔﺮدﯾﺪه اﺳﺖ. ﺑﺮﺧﻮرد ﺟﺖ ﺳﺮﯾﻊ ﺑﻪ ﭘﺮش و اﻧﺘﻘﺎل اﻧﺪازه ﺣﺮﮐﺖ ﺑﻪ آن ﺧﺼﻮﺻﯿﺎت و ﻣﻮﻗﻌﯿﺖ ﭘﺮش را ﺗﺤﺖ تأثیر قرار می‌دهد.
مواد و روش ها: در اﯾﻦ ﭘﮋوﻫﺶ ﯾﮏ ﻣﻄﺎﻟﻌﻪ آزﻣﺎﯾﺸﮕﺎﻫﯽ ﺑﺎ ﻣﺠﻤﻮﻋﻪ ای از آزﻣﺎﯾﺶﻫﺎ در ﯾﮏ ﮐﺎﻧﺎل ﺑﺎ ﺟﺪارهﻫﺎی شیشه ای به طول 10متر و عرض 3/0 متر و ارتفاع 5/0 متر اﻧﺠﺎم ﮔﺮﻓﺖ. ﺑﻪ ﻣﻨﻈﻮر ﺑﺮرﺳﯽ ﺗﺄﺛﯿﺮ دﺑﯽ، زاوﯾﻪ ﺟﺖ، شیب معکوس و زبری کف در2، 5/2 و 2/3 لیتر بر ثانیه ﺑﺮ روی ﻣﺸﺨﺼﺎت ﭘﺮش ﻫﯿﺪروﻟﯿﮑﯽ از ﺳﻪ دﺑﯽ درﺟﻪ، زاوﯾﻪ ﺑﺎ ﺣﺪاﮐﺜﺮ ﺟﺎﺑﻪ 90 درﺟﻪ، 60ﺑﺮ ﺛﺎﻧﯿﻪ ﺑﺮای ﺟﺖ و ﭼﻬﺎر زاوﯾﻪ ﺑﺮای راﺳﺘﺎی اﻓﻘﯽ ﺟﺖ ﺷﺎﻣﻞ ﺟﺎﯾﯽ اﺑﺘﺪای ﭘﺮش و زاوﯾﻪ ﺑﺪون ﺗﻐﯿﯿﺮ اﺑﺘﺪای ﭘﺮش و ﺳﻪ ﻧﻮع زﺑﺮی اﺳﺘﻔﺎده ﺷﺪ.
ﯾﺎﻓﺘﻪ ﻫﺎ: ﻧﺘﺎﯾﺞ آزﻣﺎﯾﺸﮕﺎﻫﯽ ﻧﺸﺎن داد، ﺑﺮای ﯾﮏ زاوﯾﻪ ﻣﺸﺨﺺ ﺟﺖ، در دﺑﯽ ﻫﺎی ﻣﺨﺘﻠﻒ، ﭘﺮش ﻫﯿﺪروﻟﯿﮑﯽ ﻫﯿﭻ ﮔﻮﻧﻪ ﺟﺎﺑﻪ ﺟﺎﯾﯽ ﻧﺪارد ﮐﻪ اﯾﻦ زاوﯾﻪ ﺑﻪ ﻋﻨﻮان زاوﯾﻪ ﺑﯽ اﺛﺮ ﻧﺎﻣﮕﺬاری ﺷﺪ. ﺑﺎ اﻓﺰاﯾﺶ زاوﯾﻪ ﺟﺖ، ﭘﺮش ﺑﻪ ﺳﻤﺖ ﺑﺎﻻدﺳﺖ ﺣﺮﮐﺖ ﮐﺮد و از ﯾﮏ زاوﯾﻪ ﺑﻪ ﺑﻌﺪ ﭘﺮش ﻫﯿﭻ ﮔﻮﻧﻪ ﺣﺮﮐﺘﯽ ﺑﻪ ﺳﻤﺖ ﺑﺎﻻدﺳﺖ ﻧﺪاﺷﺖ ﮐﻪ اﯾﻦ زاوﯾﻪ ﻧﯿﺰ ﺑﻪ ﻋﻨﻮان ﺣﺪاﮐﺜﺮ زاوﯾﻪ ﺟﺎﺑﺠﺎی ﭘﺮش ﻧﺎﻣﮕﺬاری ﮔﺮدﯾﺪ. ﺗﻐﯿﯿﺮ زاوﯾﻪ و دﺑﯽ ﺟﺖ ﻣﻮﺟﺐ ﮐﺎﻫﺶ ﯾﺎ اﻓﺰاﯾﺶ ﻋﻤﻖ ﺛﺎﻧﻮﯾﻪ، ﻃﻮل ﭘﺮش، اﻓﺖ اﻧﺮژی ﻧﺴﺒﯽ و ﻧﯿﺮوی ﺑﺮﺷﯽ ﺑﺴﺘﺮ ﺷﺪ. شیب معکوس و زﺑﺮی ﺑﺎﻋﺚ ﮐﺎﻫﺶ ﻣﺸﺨﺼﺎت ﭘﺮش ﻫﯿﺪروﻟﯿﮑﯽ ﮔﺮدﯾﺪ. در شیب 25/2 و فاصله dو زاویه جت 2/3 بیشترین تغییرات درمشخصات پرش هیدرولیکی مشاهده گردید.
نتیجه‌گیری: نتایج آزمایشگاهی نشان داد که باافزایش تنش برشی، باعث تشدید تاثیر شیب معکوس و افزایش زبری کف کانال به دلیل افزایش تنش برشی، باعث تشدید تاثیر شیب معکوس روی طول جهش می‌شود. در توچیه این تغییرات می‌توان ثاثیر مؤلفه رو به پایین نیروی وزن در روی شیب معکوس و افزایش تنش برشی در روی بستر زبر را عامل اصلی تغییرات دانست. وارد کردن جت به پرش با زاویه‌ای بزرگ‌تر از زاویه بی‌اثر، باعث کاهش نسبت اعماق مزدوج، طول پرش و افزایش افت انرژی و نیروهای برشی کف می-گردد.

کلیدواژه‌ها


عنوان مقاله [English]

Investigation of the effect of jet, semi-cylindrical roughness and reverse slope on hydraulic jump

نویسندگان [English]

  • Mehdi Dastourani 1
  • Ziba Roosta 2
  • Zohre Abdollahi Salmabad 2
2 Graduate student of Water Structures, Department of Water Science and Engineering, College of Agriculture.
چکیده [English]

Abstract
Background and purpose: The formation of jumps in relaxation ponds plays an effective role in the depletion of flow energy at the bottom of aquatic structures. Hydraulic jump is a type of fast variable currents that changes from supercritical to subcritical mode if the channel conditions downstream are suitable. In this research, a new method has been proposed to reduce the conjugate depths and jump lengths, in which the characteristics of a fast free rectangular jet and floor roughness have been used to influence the jump characteristics. The fast jet hits the jump and the amount of motion transferred to it affects the jump characteristics and position.
Materials and Methods: In this study, a laboratory study was performed with a set of experiments in a channel with glass walls 10 meters long, 0.3 meters wide and 0.5 meters high. In order to investigate the effect of flow rate, jet angle, inverted slope and floor roughness at 2, 2.5 and 3.2 liters per second on the hydraulic jump profile of three flow rates, the angle with a maximum displacement of 90 degrees, 60 degrees per second for Jet and four angles were used for the horizontal direction of the jet, including the displacement of the beginning of the jump and the angle without changing the beginning of the jump and three types of roughness.
Results:The experimental results showed that for a given jet angle, at different discharges, the hydraulic jump has no displacement, which was named as the inert angle. With the increase of the jet angle, the jump moved upwards and from one angle onwards, the jump did not move upwards, which was also named as the maximum displacement angle of the jump. Changing the angle and flow rate of the jet reduced or increased the secondary depth, jump length, relative energy loss and shear force of the bed. The reverse slope and roughness reduced the hydraulic jump characteristics. At a slope of 2.25 and a distance of d and a jet angle of 3.2, the most changes were observed in the hydraulic jump characteristics.
Conclusion: Experimental results showed that by increasing the shear stress, it intensifies the effect of reverse slope and increases the roughness of the channel floor due to increasing shear stress, intensifies the effect of reverse slope on the length of the jump. In these changes, the effect of the downward component of the weight force on the reverse slope and the increase in shear stress on the rough bed can be considered as the main cause of the changes. Inserting the jet into the jump at an angle greater than the inert angle reduces the ratio of conjugate depths, jump lengths, and increases energy loss and floor shear forces.

کلیدواژه‌ها [English]

  • Hydraulic jump parameters
  • Rectangular Free jet
  • Reverse slope
  • Jump length. Half cylindrical roughness
1.Abdollahi Salmabad, Z., Najafi Moud, M.H., Dastourani, D., and Khashei Siouki, A. 2021. Investigation of the Effect of both Jet and Reverse Slopeon Hydraulic Jump Characteristics.15: 2. 368-357.
2.Abrishami, J., and Saneie M. 1994. Hydraulic jump in adverse basin slopes. Iranian Journal of Water ResearchEngineering. 2: 1. 51-63.
3.Beirami, M.K., and Chamani, M.R. 2010. Hydraulic jumps in sloping channels: roller length and energy loss. Journal of Canadian Civil Engineering. 37: 535-543.
4.Belanger, J.B. 1828. Essai sur la solution numérique de quelques problèmes relatifs au mouvement permanent des eaux courantes Essay on the numerical solution of some problems relative to steady flow of water Carilian-Goeury, Paris in French.
5.Carrillo, J.M., Castillo, L.G., Marco, F., and García, J.T. 2020. Experimental and numerical analysis of two-phase flows in plunge pools. Journal of Hydraul. Eng. 146, 04020044.
6.Dastorani, M., Ismaili, K., Bahrami, M., and Dindarloo, A. 2017. Investigation of the effect of jet angle on hydraulic jump on rough bed. Journal of Soil and Water Conservation Research, 24: 6. 158-141.
7.Dastorani, M., Ismaili, K., and Theologian, S. 2016. Investigation of the effect of the angle of impact of a rectangular jet on a hydraulic jump. Journal of Soil and Water Conservation Research, 23: 3. 225-239.
8.Eslammanesh, B., Dastourani, M., and Ramezani, Y. 2021. Influence of Jet and Half Cylindrical Roughness on Hydraulic Jump Characteristics. Iranian Journal of Irrigation and Drainage. 15: 4. 842-853.
9.Gualtieri, C. 2010. RANS-based simulation of transverse turbulent mixing in a 2D geometry. Environ. Fluid Mech., 10: 137-156.
10.Khadar, M.H.A., and Rajagopal, S. 1972. Hydraulic jump in adverse channel slopes. Irrig. 29: 77-82.
11.Liu, Z.P., Guo, X.L., Xia, Q.F.,Fu, H., Wang, T., and Dong, X.L.2018. Experimental and numerical investigation of flow in a
newly developed vortex drop shaft spillway. Journal of Hydraul. Eng.1445: 04018014.
12.Nazari Aliabadi, Kh., and Akhtari, A. 2017. The effect of vertical and curved blocks on hydraulic jump characteristics in divergent rectangular sections using FLOW-3D software. Journal of Civil Engineering Modares, 17: 6. 269-280.
13.Rous, H. 1938. Fluid mechanics for hydraulic engineers. McGraw Hill Book Company. New York.
14.Stevens, J.C. 1944. Discussion of the paper by Kindsvater. Hydraulic jump in sloping channel. Journal of Trans.of the American Society of Civil Engineers. 109: 1125-1135.
15.Valero, D., Viti, N., and Gualtieri, C. 2019. Numerical Simulation of Hydraulic Jumps. Part 1: Experimental Data for Modelling Performance Assessment. Journal of Water, 11: 1. 36.
16.Wang, H., and Chanson, H. 2015.Air entrainment and turbulent fluctuations in hydraulic jumps. Urban Water J. 12: 6. 502-518.