Scaling of multiphase flow, droplet trajectories, and ice accretion on a rotating wind turbine blade

Ibrahim, Galal Mohamed Galal (2023) Scaling of multiphase flow, droplet trajectories, and ice accretion on a rotating wind turbine blade. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

This thesis presents an extended formulation of non-dimensionalized governing equations for scaling of the flow field, droplet trajectories, and ice accretion on a rotating wind turbine blade. The analytical formulation leads to similitude relationships for ice accretion to evaluate new scaling parameters corresponding to the rotation of the blade. The scaling methodology can be used to determine alternative test conditions and predict icing conditions on a full-scale wind turbine blade. The main objective of the research is to develop and apply scaling methods and similitude analyses for ice accretion prediction on a rotating turbine blade. The investigation reviews the derivation of the similitude relationships for ice accretion scaling to evaluate their importance and develops new scaling parameters corresponding to the rotation of the turbine blade. Numerical CFD icing simulations are also performed using ANSYS FENSAP ICE software to test the proposed scaling methods and verify the results. A turbine blade model is developed using blade element momentum theory (BEM). Turbine blade models are scaled up in geometry, and each case is tested at specific flow conditions as calculated using the scaling equations. Scaled conditions for velocity (streamwise and rotational), droplet size, and icing time are examined. CFD solutions for the flow field (air and droplet) are obtained in terms of velocity, droplet trajectories, pressure coefficient distributions, ice thickness, and ice shapes by quantifying the significant parameters involved in the icing process. Recommendations for parameters to be used for glaze and rime ice scaling on a rotating blade are presented and new numerical predictions are provided to support those recommendations. Numerical results and test conditions are obtained at sea level in wind tunnel facilities for experimental investigation. The research results provide valuable insight to predict ice accretion on large wind turbine blades in the field, based on smaller scaled blade models tested in a laboratory setting.

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