An Airborne Wind Turbine (AWT) is a new way to capture wind energy. Unlike traditional turbines that are fixed to the ground, an AWT flies at high altitudes where the winds are much stronger and more consistent. Because of this, it has the potential to generate more power. This project presents a detailed Airborne Wind Turbine CFD simulation to study how these machines work.

Our main goal is to analyze the airflow around the turbine’s rotating blades. To do this, we use a powerful and efficient simulation technique. This study is guided by the methods presented in the reference paper “Aerodynamic analysis of an airborne wind turbine…” by Saleem and Kim [1], which provides a strong foundation for our work.

• Reference [1]: Saleem, Arslan, and Man-Hoe Kim. “Aerodynamic analysis of an airborne wind turbine with three different aerofoil-based buoyant shells using steady RANS simulations.” Energy Conversion and Management177 (2018): 233-248.

Figure 1: The profile of the wind turbine rotor used in this simulation [1].

Simulation Process: Modeling Rotation with the MRF Method in Fluent

Simulating an Airborne Wind Turbine Using MRF Fluent requires a careful setup. First, we created the 3D geometry. It has two main zones: a small zone around the blade that rotates, and a very large zone for the surrounding air that stays still. We also added a special third zone to help control the mesh quality behind the turbine. This smart step helps us focus the computer’s effort where it is needed most. The final mesh is very detailed, with a total of 13,739,868 elements.

Next, we set up the physics in ANSYS Fluent. For a horizontal axis turbine like this one, the blades meet the wind at a constant angle as they spin. Therefore, we can use a steady-state simulation, which is much faster than an unsteady one. To model the rotation, we used the MRF (Multi-Reference Frame) technique. This is the perfect choice for an MRF CFD simulation because it treats the rotating part as a separate frame that spins at 190 rpm, while keeping the simulation steady and efficient.

Figure 2: The high-quality computational mesh used for the Airborne Wind Turbine CFD analysis

Post-processing: Wake Structure and Aerodynamic Loading

A detailed look at the simulation results gives us a complete picture of the turbine’s performance. The velocity streamlines in Figure 3 clearly show how the air flows around the spinning rotor. We can see the air speeds up as it goes around the blade tips, reaching a maximum velocity of 56.4 m/s. Behind the turbine, a large wake is formed. The wake is a long region of slower, swirling air. The presence of this wake is proof that the turbine is doing its job correctly by taking energy out of the wind.

Figure 3:Velocity streamlines showing the flow acceleration and the large wake structure behind the turbine.

The pressure contour in Figure 4 explains how the turbine generates power. We can see a clear difference in pressure on the two sides of each blade. A high-pressure zone (shown in red) forms on the front surface, while a low-pressure zone (in blue) forms on the back surface. This pressure difference, ranging from -591 Pa to 90.9 Pa, creates a strong aerodynamic force. This force is what pushes the blades and creates the torque that makes the rotor spin. The ability of this Airborne Wind Turbine Fluent simulation to capture this fundamental principle so clearly is a major achievement of this analysis.

Figure 4: Pressure contours revealing the high and low-pressure zones on the blades that generate lift and torque.