TI Calculation in WAsP Engg (2005-08-29)

[Old Forum Archivist]

Would like to know, how WENG computes the TI per directional sector for each WTG, when we lack real time data ?



Thanks



Vinod

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WAsP Team,



Wish to read your response.



Thanks.



Vinod
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You should visit the WAsP Engineering web site http://www.waspengineering.dk/ for more information and download of reports on WAsP Engineering. You may also browse the WAsP Engineering help file; there's a link to the WebHelp on the WEng web page or on the WAsP web pages (http://www.wasp.dk/Support/FAQ.html).



Should you then have more questions, you might send e-mail to wengsupport@risoe.dk.



The WAsP Team @ Risø

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[Morten]

Hi Old Forum Archivist,

The way WEng calculates TI is first to run a flow model, which predicts fields of wind speed and 3D velocity gradients. For specific sites WEng then predicts local turbulence spectra by the deformations by the mean flow and gradual adjustments to surface roughness changes. The variance of the local velocity perturbations and the turbulence intensity is then found by integration. The calculations are repeated for a number of wind directions. More details are found in: J Mann (2000) The spectral velocity tensor in moderately complex terrain, J. Wind Eng. Ind. Aerodyn. Vol. 94(2006) p. 581–602

There are certain limitations. WEng TI is for neutral stability only and it does not include turbulence produced in wakes of upstream turbines, obstacles, or behind steep terrain. Observed turbulence would include such effects and especially at low wind speeds you would see some scatter around the mean.

Sorry about the late reply. I am relatively new to this forum. Aim to be more active in the future.