The commonly observed overprediction of tip loads on wind-turbine blades by classical blade-element momentum theory is investigated by means of an analytical method that determines the exact tip-loss factor for a given blade flow angle. The analytical method is general and can be applied to any higher-fidelity computational method such as free-wake methods or computational fluid dynamics analyses. In this work, the higher-order free-wake method WindDVE is used to compute tip-vortex rollup and wake expansion in the near wake of a highly loaded wind-turbine rotor. The resulting spanwise distributions of the blade flow angle serve as input to the analytical method that is subsequently tested for the National Renewable Energy Laboratory phase 6 rotor by implementing a corrected tip-loss factor into the blade-element code XTurb. It is found that a simple modification can be added to the classical tip-loss factor in blade-element momentum theory that leads to improved prediction of blade tip loads at no additional computational expense.


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    Title :

    Methodology to Determine a Tip-Loss Factor for Highly Loaded Wind Turbines


    Contributors:

    Published in:

    AIAA Journal ; 55 , 2 ; 341-351


    Publication date :

    2016-11-10


    Size :

    11 pages




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English