Three-dimensional inverse design method, where the 3D blade profile is designed for a specified blade loading distribution, has been applied for designing a propeller fan rotor with high efficiency and low noise.
Propeller fans are widely used in a variety of equipments such as electric appliances (refrigerators, microwaves, etc.), air
conditioners, automobile radiators, and cooling devices for PCs/servers. Due to the strong need for environment-friendly
(low energy consumption, low noise) and lower manufacturing costs of such equipments, a new design technology enabling higher efficiency, smaller size, and lower noise are demanded. However, this is not an easy task and inevitably requires detail control of the three-dimensional (3-D) flow structures inside propeller fans.
A variety of the blade loading distributions (pressure jump across the blade), vortex pattern (forced vortex, free vortex, and compound vortex) and the stacking conditions (sweep angles) were specified and the corresponding 3D blade configurations were obtained. Among the 22 different designs, 14 propeller fan rotors including the reproduced baseline fan were manufactured by a rapid prototyping based on a selective laser sintering system (SLS) and tested.
It was confirmed experimentally that the best design achieved about 5.7 points improvement in the peak total to static efficiency and the 2.6dB(A) reduction in aerodynamic noise.
The flow mechanisms leading to the higher efficiency and lower aerodynamic noise were discussed based on experiments and the RANS steady flow simulations. Based on these investigations, design guidelines for the inverse design of propeller fan rotors with higher efficiency and lower aerodynamic noise were proposed.