Kinematic and Static Modelling of the Adjustable-Blade Mechanismuse din Kaplan Turbines

Abstract

One way to increase the Kaplan turbine's performance consists in adjusting the wicket gates' angle and the blade's angle based on the flow discharge of each specific location. The blade's angle can be obtained with different types of mechanisms that allow the rotation of the blades while the turbine is in operation. Nowadays, the most used mechanisms for blade rotation contain levers connected to a vertical rod, rotating or sliding inside the runner hub. For good efficiency and to avoid blocking, the blades’ driving mechanism has to be analyzed kinematically and statically. Therefore, the paper presents the kinematic and static features of the mechanism of TRRR (T – translation, R - rotation) type used for blade rotation. Numerical simulation of the main kinematic and static parameters is further performed. The optimum dimensions of the levers can be determined in order to minimize the pressure angle values. The simulation results allow the establishment of geometric and operating requirements for the Kaplan turbine, which are useful for designers and developers in the field.