3.4 Power production with turbulent wind

1. Open the Demo_a project (if not open)
In Bladed, File > Open > demo_a.prj (this project is located within the Bladed application folder, e.g. C:\DNV\Bladed 4.18\DemoModels\Demo_a\demo_a.prj).

2. Define wind turbulence
Double-click the Wind Turbulence option under Supporting Calculations in the Calculations window. Stay on the Define turbulence tab.

3. Define the wind volume width and height
Set the volume width (Y) and volume height (Z). In the video we use 100m by 110m. Then, set the Number of points (along Y and Z). In the video we want it to 10m blocks, so we set this '...along Y' to 11 and '...along Z' to 12.

4. Define the duration of the wind file
In the video we set this to 300 seconds.

5. Define the frequency of the sampling
Set the Frequency along X to define the frequency of the sampling. Bladed validates this input to let you know if it's sufficient for the algorithm to work. When the input is red this means it's insufficient. Use the arrows to the right of the input to ensure a valid input is used. In the video we use 16.6533 Hz.

6. Define Turbulence seed
As turbulence is stochastic, you need to define a seed. This will initialize the simulation in a random way. By changing the Turbulence seed you will obtain a different turbulent file (same statistical characteristics but with a different time history). In the video we keep it as the default (1).

7. Set the spectrum type
The Spectrum type defines the turbulence model. In the video we use the 'Kaimal' model. Click Define to see the characteristics of the model. In the video we set the defaults to 'IEC-3' standards, this then asks you to set the turbine hub-height (m) which is set to default (61.5). Close the dialog using the X in the top right corner to save it.
See the 'Theory manual' to understand more about the spectrum type input.

8. Generate the Turbulent wind file
Click Now next to the Generate Turbulence to create a file.

9. Choose a Run Name and specify the location for the calculation output
In the Output settings window, try renaming the run using the Run Name field. Now select a new sub-folder in the directory (you can either select the results folder or create a new folder by editing the file path and typing the new folder's name).

1. Load the new wind turbulence file
In the calculations window, in the Main calculations tab, single-click the 'Power production Loading' under the Simulations' group. Then click the 'Wind' option in the main window. Stay on the Time varying wind tab. The current Turbulent wind name needs replacing, click the '...' to the right to change the file path and load the file you created earlier.

2. Set the wind parameters
If you can't remember the mean wind speed of your wind turbulence file you can click the Set wind file defaults button (middle right).
Next, define the Turbulence intensity. As we chose the 'Kaimal' model you can set these numbers to whatever you want even after generating the file. In the video we set these to IEC standards by clicking the Set IEC turbulence button (middle right). Bladed uses IEC-3 as default.

3. Set the wind direction and flow inclination
In the video we leave these as defaults. Wind direction (from North) set to 0 degrees and Flow inclination set to 8 degrees.

4. Check the wind speed is referred to hub-height
Make sure the Refer wind speed to hub height box (left hand side, in the middle) is checked.

5. Check 'Allow wind file to wrap around'
Make sure the input Allow wind file to wrap around (right hand side, middle) is checked. This will help avoid the simulation crashing.

6. Save changes
Click OK to save and close dialog.

7. Run calculation
Click Run Now in the Calculations window.

8. Choose a Run Name and specify the location for the calculation output
In the Output settings window, try renaming the run using the Run Name field. Now select a new sub-folder in the directory (you can either select the results folder, or create a new folder by editing the file path and typing the new folder's name).

9. Start the simulation
Click OK to run simulation.

Match each wind turbulence calculation parameters in List A with a description in List B:

• Turbulence seed: Input for random number generator to create the time history from given spectrum
• Frequency along X: Controls the time resolution of the turbulent wind grid
• Number of points along Z: Controls the vertical spatial resolution of the grid
• Spectrum type: Toggles the mathematical model for the turbulence definition