Effect of Blades Shape and Duct Geometrical Parameters on Aerodynamic Performance of a Small-Sized Axial Fan

Abstract

Axial flow fans are vital in sectors such as civil, automotive, and electronic systems, where their improved performance can significantly increase fan efficiency, reduce operating costs, and minimize environmental impact. This study aims to analyze the geometric design factors affecting the performance of a small axial flow fan using experimental and numerical approaches. The study investigates the number of blades, blade shape, and shroud configuration to optimize these parameters for maximum air speed and flow rate. The experimental setup involves a customized open inlet/outlet duct design with a small axial fan mounted at its intermediate portion. Flow characteristics are measured at 17 selected points across the inlet. A three-dimensional computational fluid dynamics (CFD) model is developed using ANSYS 2020 R2 to evaluate the time-averaged performance under quasi-steady conditions by solving the RANS equations for steady, incompressible, and turbulent flow. The SST k-ω turbulence model is used to capture turbulent kinetic energy and predict flow separation under opposing pressure gradients. The model was validated against experimental data, demonstrating excellent agreement, confirming its reliability in fan design optimization. Numerical results confirmed the seven-blade fan's superior performance over the two basic six-blade designs and the proposed five-blade design. The seven-blade fan design was then further optimized by evaluating eight distinct blade design variations, achieving a 3.5% improvement in flow velocity. The optimized seven-blade fan design was then used in the shroud design optimization process, achieving an 11% improvement in flow velocity.