جستجوی مقالات مرتبط با کلیدواژه "scouring" در نشریات گروه "مکانیک"

Spillways are one of the important hydraulic structures of a dam, which perform their duties during floods in order to maintain the health of the dam. In this research, the free ogee spillway of Sahand dam is analyzed with Flow-3D modeling software and the effective hydraulic parameters on the performance of this structure including the occurrence of cavitation and scouring of the stilling basin have studied and verified with lab model. The results show that cavitation occurs in three areas along the service spillway of Sahand Dam. The ogee crest part of the spillway, the part that slope changes in the middle of the chute and the flip bucket are the parts that have the problem of cavitation. For the ogee crest part, the tip curve should be modified and the cavitation-prone part should be made longer to create a vacuum and eliminate the possibility of cavitation. If this doesn't work, aeration should be done. In the middle of the chute, aeration should be used by creating a gap in the floor. Also, the end edge of the flip bucket should not be smooth and reshaped as a curved surface. The scouring depth for the flip bucket of the Sahand dam spillway is about 7.6 meters, and to deal with it, it is necessary to organize the downstream of the spillway using a excavated pool, protection and a stone riprap.

The placement of a pier causes a three-dimensional complex flow pattern around the pier, which lead to scouring hole around the pier. In this research, modeling of scouring around piers was performed both experimentally and numerically using pimpleLPTdensFoam solver in OpenFOAM. In the first section, two different scenarios were used to simulate the scouring process. In the two numerical models, the effect of phase coupling and drag models on the scoured bed was investigated. One-way coupling with sphere drag model was implemented in the first scenario and four-way coupling with nonsphere drag model in the second one. According to the results, the first model was not satisfying, but the result of the second model was in good agreement with experimental results. The maximum depth of scour at the cross-section in numerical and experimental results was equal (6 percent error). All the simulations were done using the Euler-Lagrange approach and k-w turbulence model to simulate turbulent flow. In the second section of this research, to investigate effective parameters on the reduction of scour, three numerical models including a simple cylindrical pier and two more models using pier with collar were simulated. In order to study the effect of a collar on the reduction of scouring, the simple cylinder without a collar and then with the presence of collar at two different levels were performed. The results show that using collar in level 3.5 and level 4 may respectively lead to 49.2 and 29.7 percent reduction in maximum depth of scour.