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Welcome to IJLERA! International Journal of Latest Engineering Research and Applications

Volume 04 - Issue 01 (January 2019)

Study of the stability margin and its connection with the dynamic stiffness applied to a tidal turbine
B. Fraga De Cal
International Journal of Latest Engineering Research and Applications, pp 01 - 11, Vol 04 - No. 01, 2019
In a rotary machine, when a fluid, liquid or gas is present, located in the space between the rotor and its static part, two concentric cylinders, the fluid moves in that clearance tangentially. The forces that create the pressurized fluid are perpendicular to the surface of the static component, which can cause the so-called phenomena whirl and whip at its natural frequency. The test that is exposed is applied to the sealing seal of a tidal turbine, which has a pressurized lubrication to prevent water from entering the machine. It is revealed that the "stability margin" of a rotor decreases when the rotor speed approaches the "stability threshold", so that the rotor approaches an unstable operating range. The “Dynamic Stiffness” becomes zero at the frequency of the whirl and whip. It is also noted that a rotor operating in a fluid instability presents values of zero of the Direct and Quadrature Dynamic Stiffness in the same frequency. A stable operation of the rotor will occur at the speed limits defined by the stability margin. In this way, you must pre-calculate the limits of that margin, so that if the marine currents drive to turn the rotor out of those limits, the turbine must be stopped so as not to cause serious breakdowns. The method for that calculation is presented, in this work.
Tidal Turbines; Rotor dynamics; whirl & whip; dynamic stiffness; stability margin.
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