جستجو در تالارهای گفتگو

IMPACT OF THE CONFLUENCE ANGLE ON FLOW FIELD AND FLOWMETER ACCURACY IN OPEN CHANNEL JUNCTIONS M. Sharifipour, H. Bonakdari and A. H. Zaji Abstract Open channel junction is one of the most common hydraulic structures that are used in various practical situations such as sewer, drainage, and flood control systems. Knowing the fluid flow behavior, is one of the most important topics in designing the efficient open channel junctions. The complexity and deviation of flow in the junction’s zone disrupts the proper functioning of the flowmeter devices which are located in the cross section and causing error in their measurements. Various three-dimensional Computational Fluid Dynamic (CFD) models were developed in this paper in order to study in the velocity field and flowmeter accuracy of junctions in different hydraulic conditions and confluence angles. The results showed that by increasing the confluence angle, the junction’s downstream flow becomes more complicated, and consequently, the difference between the flowmeter measured discharge values and the real discharge value becomes greater. For the junction with 30° confluence, the flowmeter discharge prediction error is equal to 2 and 6.45% in the junction’s upstream and downstream, respectively. These values increase to 6 and 38.65% for the junction’s upstream and downstream with 90° confluence, respectively. Keywords CFD, Confluence angle, Flow field, Flowmeter, Open channel junction چکیده تقاطعها یکی از مهمتریت سازه های هیدرولیکی هستند که برای شرایط کاربردی متفاوتی نظیر، مجاری فاضلابرو، زه کشی و سیستم های کنترل سیلاب بکار می روند. شناخت رفتار جریان سیال یکی از مهمترین مسایل در طراحی تقاطع ها در کانال های روزباز می باشد. پیچیدگی و انحراف جریان در ناحیه نزدیک تقاطع ها، کارکرد وسایل اندازه گیری جریان که در آن ناحیه قرار دارند را مختل کرده و موجب ایجاد خطا های بزرگ در مقادیر اندازه گیری می شود. در این مطالعه بمنظور مطالعه میدان سرعت و بررسی دقت اندازه گیری وسایل اندازه گیری جریان در تقاطع ها در شرایط مختلف هیدرولیکی و زوایای متفاوت، مدل های سه بعدی دینامیک سیالات محاسباتی متفاوتی طراحی شده است. نتایج بدست آمده نشان می دهد که با افزایش زاویه تقاطع، رفتار هیدرولیکی جریان در پایین دست پیچیده تر می شود و در نتیجه اختلاف بین مقادیر دبی اندازه گیری شده و مقدار واقعی دبی عبوری بیشتر می شود. برای تقاطع با زاویه 30 درجه، مقدار خطای نسبی دبی اندازه گیری شده و واقعی مساوی 2 و 6.5 درصد به ترتیب در بالادست و پایین دست می باشد. برای زاویه 90 درجه این مقادیر به 6 و 38.65 درصد در بالادست و پایین دست تقاطع می رسد. منبع دانلود 28-8-6.pdf

Investigating Performance of Windscop Installed on Towers in Arid Regions with Using Computational Fluid Dynamics (Case Study: I&M Bank in Nairobi) Hooshmand Aini A., Ahmadnia B and Ahmadnia Bh. Journal. Civil Eng. Urban. 4(1): 77-80. 2014 ABSTRACT:The windscops are designed mainly to direct the wind and fresh air in the buildings. The windscops are able to gather the outside air and direct it into the building. If we want to make a windscops very effective, it shall be able to rotate on all directions. The windscops performance reaches to its top point when they are designed to direct the air for a big hall like an amusement park, etc. In this paper we paid more of our focus on performance analysis for a type of windscops which are installed on tower peaks. At first, we conducted analysis by means of GAMBIT software regarding the geometric model of windscops and the structure analysis, and then we continued to analyze them by means of FLUENT software regarding their pattern of flow. The results of such analyses were demonstrated as velocity on X&Y directions, and flow pattern. Keywords:Windscops, Natural Ventilation, CFD, Renewable Energy, FLUENT منبع: [Hidden Content] دانلود: [Hidden Content].,14-12-77-80.pdf J. Civil Eng. Urban.,14-12-77-80.pdf

Sharp-Crested Weir Discharge Coefficient Original Article, C14 Arvanaghi, H., Nasehi Oskuei, N Journal. Civil Eng. Urban. 3(3):87-91 . 2013 ABSTRACT:Weirs are useful and common devices in flow measurements. The essential parameter of each weir is to determine the flow coefficient. In this study, laboratory measurements of the water surface profile, approach flow velocity and flow rate carried out over three different rectangular sharp-crested weirs mounted in a flume. The flow was then numerically simulated by the CFD commercial software Fluent v. 6.2 in several stages. Results show that Fluent can model the flow over this type of weirs preciously. Then the effect of three dimensionless parameters of weir height (H/W), Froude number and Reynolds number on weir discharge coefficient is investigated using experimental and numerical data. For a specific value of these parameters, discharge coefficient is tending to the fixed value of 0.7. Keywords:Sharp-Crested Weir, CFD, Discharge Coefficient, Weir Height, Froude Number, Reynolds Number منبع: [Hidden Content] دانلود: [Hidden Content] JCEU-C3-15.pdf