Due to high flow velocity, the spillway surfaces of high-head dams can expose to cavitational damage. The most effective and economical method of protection from this damage is aerated to flow using aerators. In this study, a spillway aerator of the roller-compacted concrete dam of 100 m height was analyzed using two-phase computational fluid dynamic model to overcome the cavitation damage on the spillway surface. The numerical analysis with prototype dimensions was performed for various flow conditions (5223, 3500, 1750 and 1000 m³/s of flow rate), and obtained results were compared with some experimental observation in the literature. Numerical and experimental results indicated that the cavitation occurs on the surface after a certain downstream point based on cavitation indices. The air entrainment rate and air concentrations supplied by means of the aerator were determined to avoid the cavitational damage. While the experimental results can contain considerable scale effect in terms of air entrainment rate owing to, e.g., viscous effects especially for small scales, the numerical models with prototype dimensions gave much more accurate results. In other words, it can be also mentioned that the actual aeration amount is much greater than that obtained from the model experiments. The results based on numerical analysis showed that the aerator device meet air demand to prevent the cavitation damage.

In the present study, a new type of hybrid spillway termed labyrinth-shaft spillway was introduced to improve the discharge capacity and efficiency of the spillway. An advanced computational fluid dynamics (CFD) technique was used to analyze the performance of the labyrinth-shaft spillway. The hydraulic performance of the new model was investigated for different labyrinth geometries with a verified computational model. The analysis results demonstrated that the discharge capacity of the labyrinth-shaft spillway was better when compared to that of the conventional shaft spillways with the same weir heads. The discharge coefficient that reflects the efficiency of the labyrinth-shaft spillway was also much better when compared to the conventional spillway, while the opposite was observed with relatively small nappe heads. Similarly, the comparison with the findings of previous studies on labyrinth weirs in the literature demonstrated that labyrinth-shaft spillways performed better when compared to the conventional labyrinth weirs in-channel flow conditions, especially with high nappe heads. A new formula was also developed in the present study with regression analysis conducted on the collected data to calculate the discharge coefficients of the labyrinth-shaft spillway for H/P > 0.2.

Siphon-shaft spillways are constituted by covering above a shaft spillway with a hood that creates siphonic pressure. This study focused on the aeration the flow through the aerator holes placed on the hood to prevent cavitational damage in high-head siphon-shaft spillways. Three-dimensional computational fluid dynamics (CFD) technique using finite-volume method to solve Reynolds-averaged Navier–Stokes (RANS) equations for the incompressible viscous and turbulent fluids motion was performed to analyze the full-scaled two-phase numerical models. The volume of fluid (VOF) scheme was used to simulate two-phase (water–air) flow, by defining the volume fraction for each of the fluids throughout the solution domain. The accuracy of the numerical model was tested using a procedure recommended by American Society of Mechanical Engineers (ASME) for CFD applications. The numerical results showed that the aeration is highly effective in reducing siphon sub-pressures and cavitation. The optimal relative aeration diameter of 0.45 provided sufficient air entrainment to protect from cavitation and did not decrease the discharge performance too much.

Yapıların inşa edileceği zeminler eğimli olabilmektedir. Çoğu zaman tabii zemin eğimi ortadan kaldırılarak farklı kot seviyelerine oturan temeller engellenmektedir. Ancak bazı durumlarda yapı zemin eğimine göre inşa edilebilmektedir. Bu gibi durumlarda yapının zemin katında bulunan düşey taşıyıcı elemanlar farklı yüksekliklerde inşa edilebilmektedir. Bu çalışma kapsamında 3%, 5% ve 10% zemin eğimleri dikkate alınmıştır. Elde edilen sonuçların karşılaştırılabilmesi adına zemin eğimin dikkate alınmadığı referans betonarme bina için hesaplamalar yapılmıştır. Oluşturulan dört farklı yapı modeli için statik itme ve özdeğer analizleri yapılmıştır. Yapısal modellerin tamamında değişken olarak sadece zemin kat kolon yükseklikleri seçilmiştir. Yapısal analizlere esas olan diğer tüm değerler sabit olarak alınmıştır. Her bir yapısal model için periyot, yer değiştirme, taban kesme kuvvet, elastik ve efektif rijitlik ile hasar durumları için üç farklı hedef deplasman değerleri ayrı ayrı hesaplanmıştır. Her bir yapı modeli için ilk ve son hasar şekilleri elde edilmiştir. Zemin eğiminden dolayı oluşan kısa kolonlar yapının deprem performansını olumsuz olarak etkilemektedir. Zemin eğiminin artmasından dolayı zemin katta yer alan kolon yüksekliklerindeki azalma yapının rijitlik değerlerini arttırmakta, periyot değerlerini azaltıp, yapının sismik kapasitesini arttırmaktadır. Ancak zemin eğiminin fazla olduğu yapı modellerinde daha düşük yük faktörleri altında ilk hasarlar meydana gelmiştir. Oluşan ilk hasarlar eğimden dolayı en düşük yüksekliklere sahip kolonlarda oluşmuştur. Yer değiştirme istem talepleri zemin eğiminin arttığı yapı modellerinde azalmıştır.