EFFECT OF WATER INJECTION DISCHARGE AND NUMBER OF FINS COMBINATION ON PARTIAL LOAD OPERATING CONDITIONS OF HYDRAULIC RUNNER WITH FRANCIS TYPE

• Main Author: Febrilian Syah, Muhammad
• Format: Theses
• Language: Indonesia
• Subjects: Teknik (Rekayasa, enjinering dan kegiatan berkaitan)
• Online Access: https://digilib.itb.ac.id/gdl/view/73572
• Institution: Institut Teknologi Bandung

In order to meet energy demands and reduce greenhouse gas emissions, the Indonesian government plans to boost the utilization of renewable energy, including a hybrid system combining floating solar photovoltaic (FPV) technology with hydroelectric power plants (HPP). This hybrid approach, particularly relevant to the Cirata-1 hydropower plant, offers additional value by enhancing flexibility in power generation. However, operating the hybrid system with fluctuating energy inputs poses potential challenges such as cavitation due to off-design conditions, impacting the runner's performance. This thesis aims to numerically simulate and analyze the impact of flexible operation on the existing Francis-type runner at the Cirata-1 hydropower plant. The study will investigate cavitation patterns, pressure fluctuations, and runner performance under different operating conditions. The feasibility of implementing flexible operation will be assessed, and if necessary, proposed modifications using passive and active approaches will be suggested. The analysis will employ the ANSYS CFX RANS Computational Fluid Dynamics method to study pressure fluctuation distribution. Validation result shows that Francis runner model for Cirata-1 effectively represents the actual conditions. Flexible operation of the runner induces a rotating vortex rope in the partial load region and a non-rotating vortex rope in the overload region. The highest amplitude of pressure fluctuations occurs in the partial load region. To mitigate the vortex rope effect, the anti-swirl fin method with a pair of type A fins is found to be the most effective, reducing pressure fluctuations and shifting the vortex rope frequency. Additionally, injecting water at a rate of 4.45% of the inlet inflow into the draft tube significantly reduces the vortex rope amplitude without affecting its frequency. Combining these methods results in superior amplitude reduction while maintaining the ability to shift the frequency. However, both the anti-swirl fin and injection techniques lead to a decrease in power output and efficiency compared to the untreated condition. The injection method, in particular, exhibits a significant efficiency decrease due to increased water diversion to the tailrace without a corresponding increase in power output.