Publication: Study of spillway failure due to stagnation pressure at pergau dam
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Date
2023-07-01
Authors
Muhammad Asri Bin Zainudin
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Abstract
Hydroelectric dams serve as a significant source of electricity generation in Malaysia. Among the crucial components of a hydroelectric dam, the spillway plays a vital role in effectively managing and releasing excess water during periods of high inflow or flood conditions. Its primary objective is to prevent overtopping of the dam and ensure the structural safety of the entire system. However, challenges arise when the spillway chute experiences cavitation, which occurs due to the formation of bubbles caused by increasing water velocity. Additionally, the presence of cracks on the spillway can lead to the block flipping upside down due to the water pressure beneath the chute's surface. Moreover, structural failure can also result from stagnation pressure, which refers to the pressure at a point where fluid flow comes to a stop, converting kinetic energy into pressure energy. When the water jet impacts a solid surface, it generates a stagnation pressure profile on that surface. This study focuses on investigating how altering various parameters of the spillway can impact water velocity and pressure, ultimately reducing the occurrence of cavitation damage on the spillway surface using Finite Volume Method (FVM). The parameters examined include the Q value, straight wall angle of the spillway, addition of baffle blocks, and utilization of a flip bucket. Meanwhile, the corresponding variables considered are the cavitation number, water velocity, and water pressure. Based on ANSYS Fluent simulation data, the addition of baffle blocks resulted in the most significant reduction in water velocity, water pressure and cavitation damage. The value of water velocity decreasing from 26 m/s to 14.6 m/s with a water. The water pressure decreases significantly from 39 kPa to 32.3 kPa. The cavitation damage which could lead to crack propagation that could damage the spillway was reduced from level 5 to high risk to level 3 which is medium risk. This situation occurs in all water level from 636.4 m to 641.08m. Consequently, it can be concluded that modifying spillway parameters can impact water velocity, pressure, and cavitation number.