<![CDATA[This study evaluates the performance while supporting the revitalization of old Kaplan turbines at the Sawitto Mini Hydropower Plant (PLTM) by combining reverse engineering and Computational Fluid Dynamics (CFD) under conditions of incomplete technical documentation. The existing runner geometry was captured using structured-light-based three-dimensional scanning, reconstructed into a digital CAD model, and then analyzed across multiple head, discharge, guide vane opening, and runner angle conditions. Steady-state CFD simulations were employed to assess hydraulic efficiency, shaft power, and operational stability. The results indicate that the runner angle critically determines turbine performance. The 0° configuration yields the overall best performance with the highest efficiency, the most stable power-discharge characteristics, and the widest high-efficiency region on the efficiency contour map, thereby indicating the most optimal blade setting alignment. The +10° configuration increases discharge capacity and output at medium to high heads, but narrows the efficient operating range and increases sensitivity to hydraulic losses outside design conditions. The −10° configuration is relatively stable at low heads and discharges, but restricts flow and reduces output at higher loads. The integration of reverse engineering and CFD provides a practical basis for operational mapping, performance recovery, maintenance planning, and the revitalization of aging mini-hydro turbines.]]>
