Energy Dissipation on Stepped Spillways with Reverse Inclination

Subject Areas : Subjects

S.M Torabi ¹ (کارشناس ارشدگروه آبیاری و زهکشی و منابع آب دانشکده کشاورزی دانشگاه آزاد اسلامی واحد فیروزآباد و شیراز.)
امین Rostami ² (استادیار و دانشیار گروه آبیاری و زهکشی دانشکده کشاورزی دانشگاه آزاد اسلامی واحد مرودشت.)
S.A Torabi ³ (کارشناس ارشدگروه آبیاری و زهکشی و منابع آب دانشکده کشاورزی دانشگاه آزاد اسلامی واحد فیروزآباد و شیراز)
فردین Boustani ⁴ (استادیار و دانشیار گروه آبیاری و زهکشی دانشکده کشاورزی دانشگاه آزاد اسلامی واحد مرودشت.)
امیر Roushan ⁵ (دانشجوی دکتری گروه مهندسی منابع آب ، دانشگاه علوم و تحقیقات واحد تهران)

Received: 2013-09-16 Accepted : 2013-09-16 Published : 2013-08-23

Keywords: stepped spillway, reverse inclination, energy dissipation, Physical model,

Abstract :

Stepped spillways are an accessory of reservoirs and water conveyance system, which dissipate flow energy and reduce the size and costs of stilling basins (SBs). As the reverse inclination of each step helps form a small SB, therefore, energy dissipation becomes more efficient. In this study, using a Plexiglas spillway (height: 72 cm), which was installed in an experimental flume (width: 50 cm), various arrangements of numbers and inclination steps of spillway were investigated installing 12 set-ups. The first experiment was conducted on the weir itself without any steps. Another set-up was with one step without inclination and one step with reverse inclination. This procedure was continued asymmetrically with the array of 8 steps. As expected to efficiently dissipate the energy, more steps are required as the flow increases. It was observed that one inclined plus two horizontal steps provide the best energy dissipater array. Furthermore, it was revealed that there was a limit to increase the number of steps and their inclination in energy dissipation; i.e., efficiency may not be enhanced by increasing the number of inclined steps.

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