A CFD Analysis of Airfoil-Based Blades for Low-Headroom Ceiling Fans: The Role of Angle of Attack*

This study develops an integrated design-oriented optimization framework for high-efficiency ceiling fans designed for residential environments with limited ceiling height, with particular emphasis on mitigating aerodynamic issues such as inlet starvation and reduced energy efficiency. Numerical investigations based on Computational Fluid Dynamics (CFD) were conducted using the shear stress transport (SST) k-ω turbulence formulation combined with a Multiple Reference Frame (MRF) methodology to assess the aerodynamic behavior of multiple blade configurations. The optimization procedure concentrated on the NACA-6512 airfoil profile, examining the coupled influence of the angle of attack on flow topology. The results show that a 5-blade configuration with an angle of attack of 14° at the hub and 12° at the shroud yields optimal aerodynamic performance at 225 rpm. Notably, the optimized design achieved a Service Value (SV) of 9.62 m³/min·W−1 with a volumetric airflow rate of 305.8 m3/min. Experimental validation performed in an IEC 60879:2019 compliant test chamber confirmed the simulation accuracy with a deviation of less than 2%. Furthermore, this design has demonstrated stable airflow performance even at a ceiling-to-blade clearance of 250 mm, minimizing the impact of low ceilings commonly found in apartment buildings.