Table of Contents

Set up a simulation in JSON

Summary

This tutorial will take you over how to setup a simulation and different simulation types in JSON.

Prerequisites

  1. Latest version of Bladed Next Gen and Samples installed including the Bladed Python packages.
  2. Licence for Bladed Next Gen (request a licence).
  3. (Optional) Bladed Results Viewer.

We would recommend opening the samples folder in VS Code to follow along with these tutorials.

If you do not yet know how to run a simulation, please follow the instructions and checks in the Get started and Run a simulation tutorials before continuing.

Subjects Covered

By the end of this tutorial you should have:

  1. Made simple changes to the Bladed JSON input deck.
  2. Run bladed.exe with the modified input, and seen the effects of your changes.
  3. Changed the analysis to an aerodynamic information calculation.
  4. Gained an appreciation for how the turbine configuration is specified.

Sample Input Decks

There are example models provided in the samples (see the .json extension files in the samples folder).

The first section of this tutorial walks you through the same exercises that are described in the _exercise tags of demo_a_pcoeffs.json.

The second section of this tutorial walks you through the same exercises that are described in the _exercise tags of NG_IEA_15_Onshore_SteadyOP.json.

Note

Currently all values in the input decks are in S.I. units, which for many users this will be the preferred behaviour. It is the intention to implement a system of units in JSON for users who interact with the file a lot, as they may prefer to use rpm for rotor speed, degrees for wind direction, etc.

Are alternative units important to you? Let us know about it



demo_a_pcoeffs.json

In this section of the tutorial we will use the performance coefficients calculation based on the demo_a model (demo_a_pcoeffs.json). This is a very simple model which has been annotated with _description, _comment, and _exercise tags. These tags can help you understand the structure of the model better.

Exercise 1.3: Switching to an Aerodynamic Information Calculation

The demo_a_pcoeffs.json example contains a commented out definition of SteadyCalculation which defines an aerodynamic information calculation (see the top-level node _SteadyCalculation).

Have a look at the similarities and differences between SteadyCalculation and _SteadyCalculation, and then try switching the underscores of the SteadyCalculation with _SteadyCalculation. This will have the effect of commenting out the performance coefficients calculation and activating the aerodynamic information calculation.

Run bladed.exe with your modified input file.

You should be able to see the effect of your changes in three places:

  • The output in the Windows command line (cmd)
  • In the text of the $ME file
  • In the results produced
Note

The full list of steady calculations can be inferred from the auto-complete options of SteadyCalculationType, or by hovering over the properties SteadyCalculation or SteadyCalculationType. For those without it, they are AerodynamicInformation, PerformanceCoefficients, SteadyPowerCurve, SteadyOperationalLoads, SteadyParkedLoads, CampbellDiagram, BladeStabilityAnalysis, and ModelLinearisation. There is a mutually-exclusive node called TimeDomainSimulation which covers all time-domain runs (this includes start-up, emergency stop, etc) as well as hardware-in-the-loop simulations. Of the SteadyCalculationType only the SteadyOperationalLoads is currently supported.

NG_IEA_15_Onshore_SteadyOP.json

The turbine we are using is the IEA_15MW_240-RWT which is shipped with Bladed 4.16 upwards as a demo model. It is a direct-drive turbine with a rated wind speed of 10.6 m/s and a design tip-speed-ratio of 9, and the blade has both pre-bend and pre-sweep.

Open the NG_IEA_15_Onshore_SteadyOP.json file in the samples folder you have downloaded and unzipped, in VS Code or your preferred editor.

The Definition of the Calculation

The first section in the file defines the calculation to be performed by Bladed:

  "SteadyCalculation": {
    "SteadyCalculationType": "SteadyOperationalLoads",
    "Outputs": {
      "FileStem": "NG_IEA_15_Onshore_SteadyOP"
    },
    "WindSpeedRange": {
      "Minimum": 5.0,
      "Maximum": 25.0,
      "Interval": 1.0
    }
  }

In this case we are defining a SteadyCalculation of type SteadyOperationalLoads. This defines a WindSpeedRange which defines the Minimum, Maximum, and Interval at which the steady conditions will be evaluated.

The Outputs section here is reduced from the demo_a_pcoeffs.json example, as we are expecting to provide the output directory on the Windows command line (cmd) when we run bladed.exe.

Running the Calculation

You are now ready to run the calculation. Go to your terminal and run the following command:

bladed.exe -d NG_IEA_15_Onshore_SteadyOP.json -o <your output directory>

To see all available command line switches type in

bladed.exe -h

After the simulation has finished you can use the Bladed Results Viewer to inspect the output.

Conclusions

By this point it is hoped that you will have a general understanding of:

  1. Making simple changes to the Bladed JSON input deck.
  2. Running bladed.exe with the modified input, and seen the effects of your changes.
  3. Changing the simulation type.