Mesh conditions: a) mesh block; b) computational cells c) boundary conditions applied in simulation

A Study of the Conditions of Energy Dissipation in Stepped Spillways with Λ-shaped step Using FLOW-3D

Authors:

Abbas Mansoori at Islamic Azad University

Abbas Mansoori

Shadi Erfanian

Abstract and Figures

본 연구에서는 특정 유형의 계단식 배수로에서 에너지 소산을 조사했습니다. 목적은 여수로 하류에서 최고 수준의 에너지 소산을 달성하는 것이었습니다.

큰 러프니스로 계단에 대한 특정 유형의 기하학을 제공하여 수행되었습니다. 여기에서 계단은 흐름에 대한 큰 거칠기로 인식되었습니다.

이 단계에서 최대 흐름 에너지가 최소화될 수 있도록 모양과 수를 설계했습니다. 따라서 하류의 구조에서 가장 높은 에너지 소산률을 얻을 수 있다고 말할 수 있습니다. 또한, 이에 따라 프로젝트에서 저유조를 설계하고 건설함으로써 부과되는 막대한 비용을 최소화할 수 있었습니다.

이 연구에서는 FLOW-3D를 사용하여 에너지 소산율을 분석하고 구했습니다. 최대 에너지 소산을 달성할 수 있는 계단의 최상의 기하학은 관련 문헌을 검토하고 FLOW-3D에서 제안된 모델을 발명하여 결정되었습니다.

제안된 방법을 평가하기 위해 앞서 언급한 방법들과 함께 시행착오를 통해 메쉬망 크기를 분석하고 그 결과를 다른 연구들과 비교하였습니다. 즉, 스무드 스텝에 비해 에너지 소산율이 25도 각도에서 Λ자 스텝으로 가장 최적의 상태를 얻었습니다.

In the present study, energy dissipation was investigated in a specific type of stepped spillways. The purpose was to achieve the highest level of energy dissipation in downstream of the spillway. It was performed by providing a specific type of geometry for step as a great roughness. Here, steps were recognized as great roughness against flow. Their shape and number were designed in such a way that the maximum flow energy can be minimized in this stage, i.e. over steps before reaching to downstream. Accordingly, it can be stated that the highest energy dissipation rate will be obtained in the structure at downstream. Moreover, thereby, heavy costs imposed by designing and constructing stilling basin on project can be minimized. In this study, FLOW-3D was employed to analyse and obtain energy dissipation rate. The best geometry of the steps, through which the maximum energy dissipation can be achieved, was determined by reviewing related literature and inventing the proposed model in FLOW-3D. To evaluate the proposed method, analyses were performed using trial and error in mesh networks sizes as well as the mentioned methods and the results were compared to other studies. In other words, the most optimal state was obtained with Λ-shaped step at angel of 25 degree with respect to energy dissipation rate compare to smooth step.

Figure 2. Three-dimensional design of the spillway using SolidWorks 2012
Figure 2. Three-dimensional design of the spillway using SolidWorks 2012
The results obtained from energy dissipation computation
Geometrical characteristics of the í µíº²-shaped stepped spillway To investigate flow filed and hydraulic conditions, boundary and initial conditions should be applied to each of the models in FLOW-3D. 
Mesh conditions: a) mesh block; b) computational cells; c) boundary conditions applied in simulation 
Figure 6. a) 3D Numerical modelling of flow over Spillway; b) 3D experimental modelling of flow over Spillway (with the discharge of  )
Figure 6. a) 3D Numerical modelling of flow over Spillway; b) 3D experimental modelling of flow over Spillway (with the discharge of  )
Figure 7. 2D model of flow depth for each angle of the-shaped steps
Figure 7. 2D model of flow depth for each angle of the-shaped steps

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