How to find the air gap of wind turbine blades

1. Intro

In this description we use the mean x position of the blades for the location of the wave height. If this is close to zero, one can also use the waveheight values, which will be easier

2. Add dummy RIFLEX line

A dummy RIFLEX line needs to be added to the simulation to get the wave height at a position closer to the wind turbine blades. The position of the dummy line is set by the user.

3. Create a postprocessor

  • Create a postprocessor in SIMA

  • Include the Condition that you want to look at (drag it into the postprocessor)

  • Include the "signal output selection" (found in the palette to the right)

  • Draw an arrow between the Condition and the Signal Output Selection

  • Right click in the postprocessing window and press "Run from Start"

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  • Choose the results that is necessary to estimate the air gap value:

    • All blade displacement positions in z-direction

    • Wave height from the same position as the blades

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  • The waveheight time history needs to be resampled since it has a different time step than the displacement results. In the palette one can find the resample box which resamples, and the window box which ensures that the time history starts from the same time step.

  • Add three subtraction boxes to the postprocessing, and draw the lines between them as shown in the figure

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  • Find the minimum value using the "statistics" box. From this, one gets three different min values. If one only want to have one, use the merge box, and the use the statistics again, and the total minimum value is found

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