Spiral Casing Design Analysis for Francis Turbine Water Flow Distribution Using CFD Method

The most important component affecting the efficiency of a Francis turbine in converting water energy into electricity is the spiral casing, which functions to distribute water flow evenly to the turbine blades. The decrease in water discharge during the dry season causes suboptimal flow distribution and reduces turbine performance. This study aims to analyze the effect of the spiral casing design on the distribution of pressure, velocity, and flow patterns using the Computational Fluid Dynamics numerical simulation method with ANSYS Fluent software. The method used is the Research and Development approach with two variations of the spiral casing design, namely the 2538 mm inlet design and the 2600 mm inlet design. Simulations were conducted to compare the distribution of pressure, velocity, and streamline patterns in each design. The results showed that the modified design was able to improve flow distribution, reduce turbulent zones, and produce more even pressure and velocity.