Deformation of outer distributor cone in bulb turbine due to cavitation – A case study

Abstract

Deformation of outer distributor cone in the bulb turbine due to cavitation is reported. Top and bottom sides of the outer distributor cone enlarged in size from the initial dimensions at the time of erection of the turbine. The left and right hand side dimensions reduced from the erection data. The geometry of outer distributor cone became elliptical after operating machine for 28,000 h. Repairs and reconditions are made on the outer distributor cone to bring the unit into service. The same tendency of deformation is also observed at 28,000 h of working of the machine after the first recondition. Equations derived are useful to predict the condition of the outer distributor cone after a specified period of operation. Results showed that the approach is very efficient and solutions are very accurate. The developed approach proved to be very helpful to bulb turbine design engineers in both design and modification of outer distributor cone.