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Evaluation the Hydraulic Aspects of Stepped Labyrinth Spillway
تقيم السمات الهيدروليكية للمطفح المتعرج المتدرج

Authors: Jaafar Sadeq Maatooq --- Taha Yaseen Ojaimi
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2014 Volume: 32 Issue: 9 Part (A) Engineering Pages: 2174-2185
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

This study was adopted a new concept to enhance performance of stepped spillway towards more dissipation of kinetic energy along chute face through increases interlocking surface areas between the mainstream and trapping cavity recirculation vortices on the tread of chute steps and each step edge that beneath it, and increasing the interaction of the flow interference over stepped spillway. The aim of this concept is by employment the specification of a labyrinth weir by configured as a stepped spillway, to produce new steps named as Labyrinth stepped spillway. Experiments were restricted in skimming flow regimes, it have been carried out on four physical models with chute angles (35°). Where models are classified into three labyrinth stepped spillway models of three different magnification length ratios LT/W=1.1, 1.2, and 1.3, additionally; a traditional or conventional shape models were used for comparison. All physical models assembled with step height 4 cm, eight steps constructed for a total height of 32 cm and width of 30 cm .The results generally show that the energy dissipation with labyrinth shape stepped spillway was more than resulted with the traditional shape. As the magnification ratio increase, the energy dissipation observed to increase compare with traditional model.

هذه الدراسة تبنت فكرة جديدة لتحسين أداء المنحدر المدرج لزيادة قابليته على تشتت الطاقة الحركية على طول وجه المنحدر من خلال زيادة المساحات السطحية للتداخل بين التيار , والدوامات المحصورة على الوجه الأفقي للدرجات وحافات الدرجات الخارجية التي تقع أسفلها ، مع زيادة تداخل الجريان على طول وجه المنحدر. تهدف هذه الدراسة إلى استخدام مواصفات (Labyrinth weir) بتشكيل كافة درجات المنحدر ليطلق عليه تسمية (Labyrinth stepped chute). اقتصرت التجارب على نظام (Skimming flow)، التي تم إجرائها على ثلاثة نماذج مختبرية بزاوية ميل المنحدر 35 ° . حيث صنفت لثلاثة نسب مختلفة لطول التكبير LT/W Magnification length ratio)) (1.3, 1.2, 1.1) بالإضافة إلى نموذج للشكل التقليدي لغرض المقارنة. جميع النماذج تتكون من ثماني درجات إرتفاع الواحدة منها4سم مما يعطي إرتفاعاً كلياً قدره 32 سم وبعرض 30سم . أظهرت النتائج عموما , أن الشكل labyrinth للمنحدر في هذه الدراسة ذو قابلية أعلى لتشتيت الطاقة من تلك المستحصلة باستخدام الشكل التقليدي وأن كفاءة تشتيت الطاقة تتزايد بازدياد نسبة طول التكبير للنماذج.


Article
Kinetic Energy Dissipation on Labyrinth Configuration Stepped Spillway

Author: Jaafar S. Maatooq
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2016 Volume: 23 Issue: 3 Pages: 12-24
Publisher: Tikrit University جامعة تكريت

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Abstract

In present work a labyrinth (zigzag), in shape has been used to configure the steps of stepped spillway by using the physical model. This configuration does not introduce previously by investigators or in construction techniques of dams or cascades. It would be expected to improve the flow over chute. A magnifying the width path of each step to become, L T, instead of, W, will induce the interlocking between the mainstream and that spread laterally due to labyrinth path. This phenomenon leads to reduce the jet velocities near the surfaces, thus minimizing the ability of cavitation and with increasing a circulation regions the ability of air entrainment be maximized. The results were encouraging, (e.g., the reverse performance has recorded for spillway slope). From the evaluation of outcome, the average recorded of percentage profits of kinetic energy dissipation with a labyrinth shape compared with the results of traditional shape were ranged between (13- 44%). Different predictive formulas have been proposed based on iteration analysis, can be recommended for evaluation and design.

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