Success factors for the design of large high head bulb units

After reviewing historical progress in the hydraulic design of horizontal bulb units, the authors look at new technological developments which have improved performance and extended the operating range of these machines. In the past, the head limit for bulb units was around 15 m, but today maximum heads of up to 30 m can be reached even for units with large outputs. The authors describe their company’s experience in improving and standardizing bulb turbine design.