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Wind Turbine Blade FSI (Part 1)
Created using ANSYS 15.0, also works with version 14.5
To access Part 2 of the tutorial, click here.
Problem Specification
Overview
This tutorial considers the deformation due to aerodynamic loading of a wind turbine blade by performing a steady-state 1-way FSI (Fluid-Structure Interaction) analysis. Part 1 of the tutorial uses ANSYS Fluent to develop the aerodynamics loading on the blade. In part 2, the pressures on the wetted areas of the blade are passed as pressure loads to ANSYS Mechanical to determine stresses and deformations on the blade.
The blade is 42.3 meters long and starts with a cylindrical shape at the root and then transitions to the airfoils S818, S825 and S826 for the root, body and tip, respectively. This blade also has pitch to vary as a function of radius, giving it a twist and the pitch angle at the blade tip is 4 degrees. This blade was created to be similar in size to a GE 1.5XLE turbine. For more information on the dimension characteristics of this blade, please see this M.Eng report (note that model in the present tutorial has an additional 2 meter cylindrical extension at the root to make it more realistic).
The blade is made out of an orthotropic composite material, it has a varying thickness and it also has a spar inside the blade for structural rigidity. These specs, which are important for the FEA simulation, are described in more details in Part 2 of the tutorial.
The wind is coming from the z-direction at 12 m/s which is a typical rated wind speed for a turbine this size. This incoming flow makes the blade rotate at an angular velocity of -2.22 rad/s about the z-axis (the blade is thus spinning clockwise when looking at it from the front, like most real wind turbines). The blade root is offset from the axis of rotation by 1 meter to make it more representative of an actual turbine where the blades would connect to the hub. Note that the blade root is offset from the axis of rotation by 1 meter to represent the blade being connected to a hub.
Part 1
In this section of the tutorial, the blade geometry is imported, a mesh is created around the blade and the Fluent solver is then used to find the aerodynamics loading on the blade, the fluid streamlines and the torque generated. Here is more information about the set-up.
Solver: Pressure-based
Viscous model: The turbulent flow model, k-omega SST
Fluid: Air at standard conditions (15 degree celcius). Its density is 1.225 kg/m^3 and its viscosity is 1.7894e-05 kg/m*s.
Cell zone condition: Moving frame of reference (with the blade).
Main Boundary conditions:
Inlet: Velocity of 12 m/s with turbulent viscosity of 5% and turbulent viscosity ratio of 10.
Outlet: Pressure of 1 atm.
Blade: Wall
Finally, periodics are used to allow the visualization of results for three blades. Here is an example of the results that can be obtained at the end of this tutorial.
Are you ready? Let's go!