I’m new to this forum. I’m a PhD student from NTU, Singapore. My area of research is in modellling hybrid wake modelling in an windfarm. Initially for understanding BEM method and CFD analysis and for validation with experimental results, I used datas from NREL Phase VI turbine. Now I’m trying to work on wake analysis. What is the aerodynamic difference between onshore and offshore windfarms. My Professor told me NREL Phase VI turbine is tested in wind tunnels. Now we have to work on wind farms especially in offshore windfarms. So far from rotor aerodynamics, I guess there is no difference between offshore or Onshore turbines. But I’m not much aware of difference in wake aerodynamics. So can pls give me suggestion, regarding my further research and also concern in difference between onshore and offshore windfarms
The major difference between the onshore and offshore from a fluid mechanics perspective is the roughness height.
Due to vegetation and uneven surface, onshore roughness height is about 100 times larger than that of offshore.
A typical roughness height for an offshore condition is z = 0.0001m and depends on the wave height.
Please refer to Atmospheric Science book by Stull which provides more details.
Thanks!
-Sang
Dear @Jason.Jonkman
I plan to study a conventional onshore wind turbine as shown in the first figure below, but I have found that there are many different cases(https://github.com/OpenFAST/r-test/tree/main/glue-codes/openfast), as illustrated in the second figure below.
Which case is suitable for me if I mainly focus on the foundation’s fixed form in the second figure below?
Best regards,
Dear @Yangyang.Li,
The WindPACT 1.5-MW baseline from the OpenFAST r-test is a classic land-based reference wind turbine from 20 years ago: r-test/glue-codes/openfast/WP_VSP_WTurb at main · OpenFAST/r-test · GitHub. The IEA Wind 3.4-MW reference is more recent land-based reference wind turbine: IEA-3.4-130-RWT/openfast at master · IEAWindTask37/IEA-3.4-130-RWT · GitHub. I would choose between these two based on which size turbine (1.5 MW versus 3.4 MW) you want.
Best regards,
Dear @Jason.Jonkman,
Thank you for your prompt responses. However, I am more interested in the mainstream NREL onshore 5MW baseline wind turbine, which is the subject of many researchers’ studies. Could you provide a suitable case based on the second image above? I apologize for not providing the specific turbine specifications earlier.
Best regards,
Dear @Yangyang.Li,
The NREL 5-MW reference wind turbine comes in land-based configuration, but I would not say it is representative of land-based turbines. Regardless, you can find the OpenFAST model in the r-test: r-test/glue-codes/openfast/5MW_Land_DLL_WTurb at main · OpenFAST/r-test · GitHub.
Best regards,