Fan

Description

This project focuses on the acoustic analysis of a six-bladed fan using ANSYS Fluent. The main objective is to study the airflow behavior and noise generation around the fan under specific operating conditions. The simulation aims to predict the broadband noise levels and to examine the distribution of the pressure and velocity fields, in order to understand the fan's combined aerodynamic and acoustic performance. This analysis helps identify the regions chiefly responsible for high noise generation and can be used to improve fan design for greater efficiency and reduced noise.

Geometry & Mesh

The fan geometry was created in ANSYS Design Modeler and consists of three zones representing the flow domain and the fan structure. The model features six blades attached to a central hub within a cylindrical enclosure. The geometry was imported into ANSYS Meshing, where a non-conformal, unstructured mesh was generated. A fine tetrahedral mesh was used to capture the complex flow features around the blades, resulting in approximately 3 million elements. The mesh quality was carefully checked to ensure accurate flow and acoustic predictions while maintaining computational efficiency.

Methodology

The simulation was performed in ANSYS Fluent using a pressure-based, steady-state solver. Turbulence was modeled with the standard k–ε model together with standard wall functions to account for near-wall behavior. The fan rotation was represented using the Multiple Reference Frame (MRF) approach at a rotational speed of 3000 RPM, and pressure inlet and pressure outlet boundary conditions were applied at the corresponding surfaces. The coupled algorithm handled the pressure-velocity coupling, and hybrid initialization was used to aid convergence. For the acoustic analysis, the Broadband Noise Sources model was employed to estimate the noise generated from the turbulent fluctuations in the flow.

Conclusion

The results include contours of pressure, velocity, and acoustic power level across the fan domain. The pressure contours show higher-pressure regions near the leading edges of the blades and lower-pressure zones at the trailing edges, reflecting the lift effect produced by the rotation. The velocity contours reveal the maximum airspeed near the blade tips, demonstrating the strong tangential flow driven by the rotation. The acoustic power level plots indicate that the highest noise is concentrated around the blade tips and the outer casing, where the turbulent interactions and velocity gradients are most intense.

Overall, the simulation successfully captures both the aerodynamic and acoustic behavior of the fan under steady operating conditions, showing how a broadband-noise acoustic model combined with the MRF approach can locate the dominant noise sources on a rotating fan and inform quieter, more efficient designs.