An analysis of the existing and prospective blade seal designs for Kaplan runners was performed. The selected design type provides the maximum ecological safety for Kaplan runners. A 3D model of runner hub sector with the trunnion, inner and outer bushes of blade trunnion was generated taking into account the cyclic symmetry of the runner design based on the modern automated design engineering system. A diagram of application of external loads from the blade and lever to the given 3D model of the Kaplan runner hub segment was developed. The contact problem was formulated to determine the stress-strain state as well as the contact pressures at the inner and outer bronze bushes of the Kaplan runner blade trunnions in different operating conditions. The problem was formulated for the finite element method, taking into consideration the diagram of external load application and contact restraints to the given 3D model of the Kaplan runner hub sector in the software package for engineering calculations. Using calculation results, principal stress distribution diagrams and the distribution diagram for the contact pressure at the outer and inner bronze bushes of blade trunnions were obtained. Strength calculation results were processed using the data of principal stress distribution diagrams, and the contact pressure values at the inner and outer bronze bushes of blade trunnions were determined. A methodology for further use of the given analytical model in the evaluation of stress-strain state of Kaplan runners involving modern automated design engineering systems and software package for engineering calculations was developed. The comparison of stress-strain states of the blade trunnion bushes was performed for the old and new designs of the Kaplan runner seal.

The main objectives of the reconstruction are stated. Those are: increase of the service life of the hydro-turbines of Dnipro Cascade, enhancement of their efficiency, power, and environmental safety, extension of the power control range of the hydro-power plants, assurance of the reliability and improvement of the operating safety of their equipment and structures, meeting the environmental requirements, improvement of the quality of the generated electric power after control system rehabilitation. The article deals with and analyses the chronology of the creation of the optimal design for a vertical Kaplan hydro-unit oil piping taking into consideration the half a century operational experience and stages of hydro-turbine modernization for Dnipro-2 HPP. The experience in improvement of the hydro-unit and oil head system control design is generalized, from the unified solution to the creation of the all-new design. The methods of the oil system rod machining and preliminary control are amended. The temperature control of the automatic unit shutdown in case of heating of oil head bushes is introduced into the control system. The oil piping installation method is improved and step-by-step checking of the oil piping installation centering is introduced. As a result of implementation of a package of design and process engineering solutions, the optimal design of the oil piping of improved reliability was created. It decreased the unscheduled downtime of the units and cut expenses on their maintenance providing the cyclic recurrence recommended by the standards for the operation of the oil pressure device pumps and thus, decreased the electric power consumption for balance-of-plant needs. The objects of the implementation of the developed oil piping design are given.