Sound Generation on an Airfoil, 3 Different Attack Angles

Sound Generation on an Airfoil, 3 Attack Angles CFD Simulation, ANSYS Fluent Acoustic Model Training

The problem simulates sound pressure waves around an airfoil using ANSYS Fluent software.

Topics related to sound waves are very important in aerospace applications and fields; Because the sound waves produced in aerospace devices such as airfoils are very high. This project examines the sound waves generated around the body of an airfoil.

This project uses an acoustic model in Fluent software to simulate and analyze sound or acoustic waves. Definitive density is equivalent to air density, i.e., 1.225 kg / m3. Sound speed is equivalent to sound speed in the air, i.e., 340 m / s, and the reference acoustic power equals 1e-12 pascal.

In this modeling, the NACA0012 type airfoil is designed, and the airflow moves towards this airfoil with a speed equal to 68 m/s.

This project has been done in three modes; So, the airfoil’s angle of attack in these three cases is equal to  0, 7, and 14 degrees, respectively. The angle of attack is equal to the direction of the wind direction with the airfoil chord.

The present model is designed in two dimensions using Design Modeler software. The model includes a NACA0012 airfoil located inside a computing environment with a maximum length and width of 400 m and 200 m.

The airfoil chord length is equal to 1 m and is designed horizontally. To simulate airfoils, you should use the Airfoil Tools website and receive the set of coordinates of the constituent parts of the airfoil body in the form of a point cloud and import it into the Design Modeler software.

The meshing has been done using ANSYS Meshing software, and the mesh type is structured. The element number is 231840.

Sound Methodology

The Broadband Noise Sources model has also been used to define the type of acoustic model of the present work.

Sound Conclusion

At the end of the solution process, two-dimensional contours related to pressure and velocity and diagrams of changes in velocity and acoustic power level in all three states are obtained from different attack angles.

The figures show the change in acoustic power level (dB) or the amount of sound pressure in terms of location in the longitudinal direction. This location indicates a few meters before the location of the airfoil body, then on the surface of the airfoil body, and finally a few meters after the airfoil body.

As it turns out, the sound wave is generated after the airflow hits the airfoil body. According to the figures, it can be said that when the airfoil’s angle of attack is zero, the sound is propagated at a greater distance after the airfoil. However, the more the angle of attack, the more amplitude indicates the sound is more limited.