OpenFAST Tutorial (2/4) - Wind turbine in steady wind

Summary

In this engaging tutorial from Centrale Nantes Research, viewers are taken on a comprehensive journey through the intricacies of simulating a wind turbine using OpenFAST in a steady wind scenario. The video builds upon the initial exploration of OpenFAST, this time incorporating the AeroDyn module to simulate aerodynamic forces on a freely rotating wind turbine, as well as the InflowWind module to accurately simulate incoming wind conditions. Through detailed explanations and demonstrations, viewers learn how to configure various modules, use Python for data processing, and understand the aerodynamic theory and practical configuration behind turbine simulation.

Highlights

• Introduction to simulating a freely rotating wind turbine 🌪️
• Explanation and configuration of AeroDyn module for aerodynamic analysis 📝
• Guidance on using InflowWind to simulate environmental wind conditions 🌤️
• Illustration of using Python for processing simulation output data 💻
• Insight into future tutorials including generator modeling with ServoDyn 🔍

Key Takeaways

• Learn how to simulate a rotating wind turbine in steady wind using OpenFAST 🌬️
• Understand the roles of AeroDyn and InflowWind modules in wind turbine simulation 🚀
• Explore the blade element momentum theory to calculate aerodynamic forces 📘
• Configure and execute simulations with precise environmental settings 🛠️
• Utilize Python for post-processing simulation data efficiently 🐍

Overview

This captivating tutorial video focuses on simulating a wind turbine's response in a steady wind using the OpenFAST tool. The tutorial provides a thorough walkthrough of integrating and configuring critical modules such as AeroDyn for aerodynamic calculations and InflowWind for simulating the incoming wind profile, setting a strong foundation for anyone interested in wind turbine simulations.

The creator, Centrale Nantes Research, dives deep into the technical aspects by explaining aerodynamic principles, module configuration, and executing simulations. Notably, the video emphasizes the blade element momentum theory, detailing how aerodynamic forces are calculated at different blade sections, enhancing the viewer's understanding of core aerodynamics involved in turbine simulations.

A step-by-step guide using Python for post-simulation data analysis is provided, ensuring that viewers can interpret complex output data effectively. The video sets the stage for upcoming tutorials that will explore ServoDyn and generator modeling, promising exciting developments for viewers eager to understand comprehensive turbine control systems.

Chapters

• 00:00 - 01:00: Introduction and Recap In the second part of the OpenFAST tutorial, the introduction recaps the first session. It covered the elasto-dynamic module used for structural modeling, explained model shape prediction in ElastoDyn, and included a practical example of running OpenFAST with a fixed, non-rotating setup.
• 01:00 - 02:30: Aerodynamic Simulation and Modules Introduction This chapter introduces the topic of aerodynamic simulation in the context of wind turbines. The focus is on simulating a fixed wind turbine in a steady wind condition. The chapter begins by referencing previous lessons where the eloine configuration file and the main FSC file were tuned, leading up to a successful simulation launch. The new topic covered is the introduction of a module to simulate wind turbines without generators, characterized by freely rotating turbines subjected to a power L profile of wind. This profile describes the steady wind conditions impacting the wind turbine.
• 02:30 - 04:00: Blade Element Momentum Theory The chapter discusses the Blade Element Momentum Theory, focusing on its application to wind turbines. Initially, the existing framework only incorporated the eloine module, which modeled the platform, tower, and nasel. To apply aerodynamic forces to the turbine, the aerodine module is introduced. However, the aerodine module has limitations as it cannot simulate the inflow or incoming conditions fully.
• 04:00 - 09:30: Configuration Files Overview The chapter introduces the concept of using configuration files in simulations, specifically focusing on simulating wind using a module called the inflow wind module. Before delving into modelization, the chapter provides an overview of how the aerodine system operates. Aerodine's functionality is based on the Blade Element Momentum (BEM) Theory, which combines two theories: the actuator disc theory and another unnamed theory. The chapter seems to set the stage for more detailed simulation processes by providing this foundational understanding.
• 09:30 - 16:00: Simulation Execution and Results Processing The chapter explores the concept of blade element theory, which involves dividing a blade into sections to calculate aerodynamic loads. By focusing on sections made of the same airfoil, aerodynamic loads can be easily computed from existing airfoil tables that contain lift, drag, and moment coefficients.

OpenFAST Tutorial (2/4) - Wind turbine in steady wind Transcription

• 00:00 - 00:30 uh welcome everyone to this second part uh on our tutorial with open fast last time uh we saw an introduction to open fast where we um we learned about the elast dine module and how it was used for structural modelization we explained the model shape prediction that is used in eloine and we saw our first example of running um open fast with a fixed non- rotating
• 00:30 - 01:00 wind turbine so the one that you can see on the screen we saw how to tune the eloine configuration file uh and the main FSC file and finally we launched a simulation today we will learn a new module uh with this simulation so we will simulate a fixed wind turbine in a steady wind with a power L profile so this is the the profile of the wind that will be uh coming to the turbine and the turbine will will be freely rotating which means there is no generator for
• 01:00 - 01:30 now but it will just rotate in the wind so um for this example we will need new modules last time we only used the eloine module which modeled the platform the Tower and the nasel today we will need the aerodine modules because we want to apply aerodynamic forces to our turbine so this is the module that we going to use and aerodine is not um able to simulate the inflow uh the incoming
• 01:30 - 02:00 wind so we will also be using the inflow wind module to simulate the the wind so before we go to the modelization part I will explain a bit how arine works so let's see it so the way aerodine works is using the blade element momentum Theory this theory is a combination of two Theory uh the first one is a dis dis actuator Theory Theory and the second
• 02:00 - 02:30 one is the blade element Theory um basically so the blade element Theory it says that you can split the blade into each section and compute the aerodynamic loads on each section and then sum all of them um it's quite easy to compute the aerodynamic loads on one section if it's composed of the same air foil because you only have to look at the airfall tables with the lift and drag coefficients and moment coefficient so
• 02:30 - 03:00 to do that you only need the to know the speed on the blade at this location and to know the speed on the blade you only need to you to know the incoming wind speed and the blade speed so you already know the blade speed because of the because you know the thank to Eline we know the rotor speed so the last thing that we need um is the incoming wind speed and to get this speed we use the
• 03:00 - 03:30 act actuator dis Theory basically using ban low if you know the the wind speed upwind from the turbine you can get the wind speed on the rotor disc and you can do that for each um analys of the rotor so in the end you can compute the the loads on each section of the blade and then you can sum all of them to get the aerodynamic loads on the wind turbine so
• 03:30 - 04:00 this is basically how how aerodine Works in its simplest form so let's have a look at um aerodine configuration files so here we are in our uh home folder for this simulation and you can see that we still have the eloine file the FST file and the Tower and the blade file that we need to that we need for for eloine to run but we have additional files so the first one is the aerodine file so let's
• 04:00 - 04:30 open it and see what's inside so um this is the parameters that you can set for the aerodine module so first you can specify some environmental conditions here as you can see when you set them to default it will use the conditions that are already defined in the FST file so we don't need to change that then we have um we can specify what we want to use for the blade element momentum Theory um because
• 04:30 - 05:00 the theory I explained just earlier is very simple and then we have additional par parameters that we can set to improve um to correct the this Theory so here you can set the one that you you want to use the correction correction factors that you want to use um then we can go to the airfall section and here you specify um how you will provide a rodine with the air foil
• 05:00 - 05:30 parameters because as we said we need the air foil coefficient tables to compute the aerodynamic loads so this is where they are specified so here you basically tell aerodine that you will use all of these air fils in your simulation we have the blade file and this file will be the one that is important for specify for computing the aerodynamic clads so let's see where this file is
• 05:30 - 06:00 um is this one okay and in this file you have the blade span so here my blade is um 62 m long and along the blade span I will specify some information so the curvature the the angle of the blade um the this cord and here I will tell you tell aerodine which air foil is being used on each section so this is
• 06:00 - 06:30 the important part back to the aod aerodine file we then specify um aerodynamic properties of the Tower so here the tower is symmetrical we don't have lift and moment coefficient we only have drag coefficients so here they are and we also specify the diameter of the Tower and then we already go to the output section here we specify which outputs we want so you can find the names and the description of the outputs
• 06:30 - 07:00 in the same Excel file that we mentioned in the last video so we are all set for aerodine so now uh let's see for the uh incoming wind so we need to provide the open fast with information about the incoming wind uh so we use the inflow wi module here we can specify different type of wind you can have a constant wind uniform wind so it can vary but it's the same in all the simulation can have some
• 07:00 - 07:30 turbulant wind can also use precomputed time series and finally we can use a cfd precursor but for now we will just use a constant wind uh the only uh specification will be that the wind is um um is undergoing the the atmospheric boundary layer so it's not the same at each altitude uh here we can see uh that closest to the surface the the wind is
• 07:30 - 08:00 slower and the higher we go the faster the wind is so we just need to specify this and we do it using a power low so let's uh let's look at the El the inflow configuration file so here it is so in our um El in in our inflow configuration file uh we will select
• 08:00 - 08:30 this wind type so the first one which is the steady wind type and we will specify the wind speed um at a given height and this height will be 90 M here uh so it means that the wind speed at 90 M will be 8 m/ Second and the power low exponents so will be 0.1 so it's a recommendation from um I when we use this type of uh when we use wind on
• 08:30 - 09:00 the C then you have parameters but these parameters depends on the Wind type that we use and for for us with wind type one we only need these parameters and then we can go to the output list where here we choose to specify the wind velocity at different heights to study the wind profile so we are all set with the inflow wind um file and now we just need to tune the FST file to accommodate for the new uh
• 09:00 - 09:30 modules that we are going going to use so if you remember in the first video we only set the eloine module to true but today we will add other modules so here we will tell open fast to use the inflow wind module and we also we will also tell it to use a aerodine uh because we are using aerodine version 15 uh we will use we will set this
• 09:30 - 10:00 parameters to two and then we need to to tell um open fast where to look at the files for the the configuration files for each module so here are the location and then we are all good so we can the start the simulation so same as before I have my [Music] um I have my open fast executable here so I will go to this
• 10:00 - 10:30 folder I will open a terminal window so first I call for my open fast executable and then I will uh give it the FST file so the main file for the simulation and then we can start
• 10:30 - 11:00 so I have fast forwarded to the end of the simulation because um it can be a bit long with the uh video recording on uh but we just finished the simulation so let's move on and um have a look at what's new so last like last time we have uh new files that have been have been created um the out and outb file so you can have additional files that are being generated but for now we just uh need we just want the to look at the out
• 11:00 - 11:30 file so like last time we have columns in this out file uh where we can see the each data that we wanted to Output but um today we'll do a bit more so we will uh open the out file with python and we will use Python to postprocess the file so here um I'm using a vs code with python
• 11:30 - 12:00 um and I'm using the open fast toolbox so the open fast toolbox can be downloaded on open fast GitHub uh like the open fast executables and um using this toolbox I will um use the function fast output file and then I will use the two data frame uh method so basically what it does it will um load the output file the that we just saw on notepad++ and it will um load it to a data frame so let's
• 12:00 - 12:30 see what it does so I'm running it in interactive window because it's easier now okay so it uh printed the some figures but for now I just want to have a look at the data frame uh so we print it in the interactive View and we can see there is 2,000 rows so our simulation run for 200 seconds and we wanted the 0.1 second of time steps so that's good and we have 43
• 12:30 - 13:00 columns so each column corresponds to a particular um time theory so first we have the wind velocity at various Heights uh we can see yeah we have wind velocity at 10 different Heights and then we have other data so we can have a look at everything that we can see uh so we have the velocity we have the azimo of the rotor the rotor speeds
• 13:00 - 13:30 generator speeds and many more data so now we just uh we will have a look okay so we'll have a look at the data that we simulated so uh first we can look at the rotor speed uh so we can see that it starts from zero um during the simulation that the
• 13:30 - 14:00 initialization phase the rotor was not turning then it starts increasing and it it really which is 10 um rotation per minute which is kind of the optimal for this turbine uh so when it's working um well with the controller it runs at around 10 RPM but for now because it's not um slowed down by any generator it uh continued to accelerate um to um much higher value
• 14:00 - 14:30 until it was stopped when the when the drag on the the air friction on the on the blades was enough to slow it down to equ equilibri with the with the lift forces um so then we can have a look at the um the force on the water uh so this is the force and the downwind
• 14:30 - 15:00 direction so we just we can just say that it will um maybe bend the turbine a little but it's not too high Force then we can show uh the RoR uh Arrow power so here uh you can see that this um Power first increases as the rotor accelerates but then it slow it slows
• 15:00 - 15:30 down it's because as I said the at the end of the at the end of the simulation the rotor spins at the speed where the um aerodynamic forces so the the lift and the drag on the blades equilibri so the the Air does not provide any more power to the blades so that's why it's um it's slowing down and then we cannot uh see the generator generator power because in this simulation we have no
• 15:30 - 16:00 generator because in open fast if you want to model the generator you need to use Servo dine and we haven't used it here but in the next video we will use Servo dine to model the generator and to have some control to our wind turbine to avoid it spins too fast so thank you for watching and see you in the next video