An integrated study of the design method for small axial-flow fans, based on the airfoil theory

摘要

This research is aimed to establish an integrated design scheme through combining the cascade theory and inverse design method for the small axial-flow fans. At first, a reliable set of low-Reynolds-number aerodynamic characteristics for National Advisory Committee for Aeronautics airfoils is constructed to serve as the fan design database via the computational fluid dynamics (CFD) calculation incorporated with a dependable turbulent model. Then, with the inputs of design conditions and few geometric settings, this design program can generate a fan configuration to meet with the desired performance requirement. Furthermore, by changing the operating flowrate for this fan geometry, this design approach can also yield the axial velocity and the pressure distributions for various operating points over the entire performance curve. Consequently, this feature enables the design engineer to foresee the actual fan performance delivered under different system resistances. Thereafter, a computer numerically controlled – fabricated prototype and a three-dimensional numerical model are chosen to validate the design prediction of fan performance via both test and CFD approaches. As a result, a slight deviation among the designed, experimental, and numerical outcomes is observed throughout the P–Q performance curve. In conclusion, this systematic and user-friendly inverse design program not only provides the fan engineer's design ability to meet with the performance requirement at the on-design point, but also the predicting capability on the off-design characteristics.