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6
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بررسی پارامترهای موثر بر عملکرد هیدروفویل در نزدیکی سطح آب
Investigation of Effective Parameters on the Hydrofoil Performance near the Free Surface of Water
http://jhyd.iha.ir/article_85405.html
10.30482/jhyd.2012.85405
0
1
In this study, a numerical method is used to assess the effect of thickness, camber, submergence depthand flow velocity around a submerged hydrofoil. A pressure based algorithm is used to solve Navierstokesequations, and Volume of Fluid (VOF) approach is applied to simulate two-phase fluid (waterand air). The model and second order upwind scheme have been used for turbulence models anddifferential schemes, respectively. For verifying, a part of results is compared with publishedexperimental results. The numerical and experimental results show excellent agreement; thus, theprocess of numerical simulations is confirmed. The results of this study illustrate that the lift and dragcoefficients increase with rising the thickness of the hydrofoil, but the lift to drag ratio has adownward trend. On the other hand, the lift and drag coefficients increase with growing the camber ofthe hydrofoil, but lift to drag ratio has upward trend. Therefore, to opt the best section of the hydrofoil,the less thickness and the high camber are more desirable to getting high hydrodynamic performance.The switched of the hydrofoil section obviously affects the airflow and boundary layer formed on thefree surface of water. Moreover, lift and drag coefficients become high by increasing the submergencedepth and angle of attack, as a result lift to drag ratio increases. Lift and drag coefficients aredecreased by increasing flow velocity, and lift to drag ratio has a downward trend.
1
17
محمدحسن
جوارشکیان
M.H.
Javareshkian
ایران
javareshkian@ferdowsi.um.ac.ir
علی
اسماعیلی
A.
Esmaeili
ایران
aliesmaeli30316@yahoo.com
0
تحلیل همزمان جریان غیرماندگار و پاسخ های دینامیکی سازه خطوط لوله به روش MOC-FDM
Coupled Analysis of Fluid Transients and Structural Dynamic Responses in Pipelines by MOC-FDM
http://jhyd.iha.ir/article_85406.html
10.30482/jhyd.2012.85406
0
1
Water hammer is a type of transient flow in pipelines which may in general be produced due to valveclosure or sudden shut down of pumps. Transient flow creates sudden variation in the velocity andpressure of fluid flow in the pipelines which in effect may induce some dynamic vibrations in thestructure of pipe. Furthermore, such structural vibrations can affect the fluid flow. Taking into accountthem is necessary for modeling of fluid-structure interaction. In this paper the fluid-structuralinteraction (FSI) of water hammer in pipeline systems are investigated. Two sets of hydraulic andstructural equations with common variables have been numerically analyzed through MOC-FDMsimultaneous solving process which has been prepared by a computer-assisted program. Someexamples have been solved by this method, with satisfactory results. This indicates that fluid-structureinteraction can have critical effect on the value of fluid pressure.
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31
سید محمود
جزایری مقدس
S.M.
Jazayeri Moghaddas
دانشگاه شهید چمران
ایران
mahmoodjazayeri@yahoo.com
حسین
محمدولی سامانی
H.
Mohamadvali Samani
ایران
hossein.samani@gmail.com
0
تاثیر پساب شهری بر سرعت و تنش برشی غیررسوبگذار رسوبهای چسبنده
The Effect of Wastewater on the Non-Settling Velocity and Shear Stress of Cohesive Sediments
http://jhyd.iha.ir/article_85407.html
10.30482/jhyd.2012.85407
0
1
Sedimentation in open channels is one of the basic problems in the management of irrigationnetworks. Complexity of behavior of cohesive sediment transport makes determination of the criteriafor open channel design to be difficult. The purpose of this study is to determine non-settling velocityand non-settling shear stress for open channel flow containing wastewater and suspended cohesivesediment. Experiments were carried out in an annular flume located in the hydraulic laboratory ofShahrekord University, Iran. The sediment samples were taken from Pirbalut dam reservoir, locatedupstream of Northern Karun basin. The result showed that wastewater content in flow causes thesuspended sediment deposition and flocculation to be likely increased. It also caused the threshold ofnon-settling velocity to be increased at a rate of 10% compared to pure water. A similar result was alsoobtained for threshold of shear stress. The results obtained from this study were compared and theresults showed that the empirical methods were not capable in calculating non-settling velocity foropen channel flow containing waste water and suspended cohesive sediments. The results also showedthat the Froud number should be more than 0.47 for non-settling condition of suspended cohesivesediments.
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42
میلاد
خواستار بروجنی
M.
Khastar-Borujeni
ایران
حسین
صمدی بروجنی
H.
Samadi
عضو هیات علمی دانشگاه شهرکرد
ایران
samadi153@yahoo.com
کاظم
اسماعیلی
K.
Esmaili
ایران
esmaili@um.ac.ir
0
توسعه مدل عددی برای پیش بینی فشارهای دینامیک در جریان کانال های باز با شبکه منحنی الخط غیرمتعامد
Development of a Numerical Model for Predicting Dynamic Pressures in Open Channel Flow using Non-Orthogonal Curvilinear Coordinate Grid
http://jhyd.iha.ir/article_85408.html
10.30482/jhyd.2012.85408
0
1
A 2DV numerical model is developed for solving unsteady Navier-Stokes equations with the abilityfor calculating dynamic pressures in non-orthogonal curvilinear coordinate grids for free surfaceflows. The model is based on fractional step method (or projection method). The free surface elevationis calculated using continuity equation. The present method uses the advantages of shallow watermodels for calculating free surface elevation (even in cases with large changes) and benefits theflexibility of moving non-orthogonal grids. Moreover, this method presents the ability of developing ashallow water solver to take into account the dynamic pressures.The simulation of water elevation in a gradually varied flow, showed the ability of mesh adaption inmoving and curved boundaries. Comparing the results of the model with experimental data and othernumerical models, for flow passing over a hump and trench, confirms the ability of the developedmodel for simulating the free surface flows. Having the ability of calculating free surface and dynamicpressures, the model can therefore be applied to rapidly varied flows.
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58
زهره
دهقان بهابادی
Z.
Dehghan Bahabadi
ایران
dehghan_db@yahoo.com
محمدرضا
هادیان
M.R.
Hadian
ایران
mr_hadian@yazduni.ac.ir
امیررضا
زراتی
A.R.
Zarrati
ایران
zarrati@aut.ac.ir
0
مطالعه تاثیر لایه سپری بر آب شستگی پایه پل، تحت اثر جریان دائمی (بخش یکم)
Armoring Effect on Local Scouring around the Bridge Pier under (Part1 :) Steady Flow
http://jhyd.iha.ir/article_85409.html
10.30482/jhyd.2012.85409
0
1
In this study armoring effect on local scouring around bridge pier under steady flow condition wasinvestigated based on model experimentation. Different combinations of bed-armor layers wereemployed. Three circular piers of 22, 33 and 42 mm were used. Results show that while small bedparticles are under the protective effect of armor layer, increasing the total scouring depth, yields anincrease in the secondary armor layer depth until the armor layer itself is not influenced by the horseshoevortices. The minimum stabilized secondary armor layer is identical to the armor grain size.Results showed that there is not meaningful correlation between total scouring depth and B/d (where Bis the pier diameter and d is the mean bed grain sizes) for B=33 and 42 mm. However for B=22 mm,increasing B/d tends to increase the total scouring depth. For the armor layer particles size of 2.36 mmthe armoring effect for B=22 mm is vanished. The most important parameters in evolution of scouringdepth are the armor layer grain size and the armor layer thickness.
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75
عبدالرضا
کبیری سامانی
Abdorreza
Kabiri-Samani
دانشیار، دانشکده مهندسی عمران، دانشگاه صنعتی اصفهان
ایران
akabiri@cc.iut.ac.ir
0
مطالعه توزیع فشار دینامیکی بر روی بستر پرتاب کننده جامی مرکب
Study of Dynamic Pressure Distribution over the Bed of Compound Flip Buckets
http://jhyd.iha.ir/article_85410.html
10.30482/jhyd.2012.85410
0
1
Flip buckets are usually placed at the end of chute spillways or outlet conduits of high dams. Theprojected jets from these buckets jump into plunge pools to dissipate the destructive energy ofplunging jets. Compound flip bucket is a special bucket with a non-zero degree of cross sectionalslope, followed by a curvature in its longitudinal direction. These structures are very suitable forrestricted geometries and conditional topographies. Although, studies of flow over flip buckets startedmany years ago and valuable information is available for similar buckets, still there are uncertaintiesregarding the flow over compound flip buckets. Therefore, in this study the hydraulic parameters suchas pressure, velocity and depth of flow on these structures were evaluated. Two chute spillways withtheir flip buckets were used to check the pressure distribution and its variation with different hydrauliccharacteristic along the compound flip buckets. The scaled model of Gotvand dam (south of Iran) atWater Research Institute of Iran was used for this study. The Froude number varies in the range of 3.5to 7.5. The results are presented in the form of dimensionless equations, which are calibrated based onthe present results. The location of maximum dynamic pressure on the bed of the compound flipbucket is also determined.
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90
امید
امین الرعایایی یمینی
O.
AminoroayaieYamini
ایران
o.aminoroaya@sina.kntu.ac.ir
محمدرضا
کاویانپور
M.R.
Kavianpour
ایران
kavianpour@civilejournal.org