A Novel Axial Fan Concept Developed Using Parametric Optimization
D1 Fan Design
Axial fans are used in a wide range of applications. Therefore, when developing a new generation of axial fans, in addition to typical development targets such as efficiency and noise, other aspects must be considered. In evaporation applications for instance, icing of the fan blades and housing could lead to blockage of the motor and must be prohibited. Another important aspect in this application is the throw distance of the fan.
It does not seem to have that much potential to improve the mentioned development targets when further developing the state of the art concept of a fan stage of an axial impeller with tip gap and guide vanes which are often part of the fan housing. So, the decision is made during the development process to take a different approach: A shrouded impeller with a slightly diagonal approach combined with an inlet nozzle such as typically used in combination with centrifugal fans. The housing has guide vanes included and deflects the airflow into the axial direction to keep the outlet characteristics of an axial fan. During the development process, the structural mechanics and the aerodynamics of the fan are simultaneously optimized by using an automated workflow based on a parametric CAD model. This approach reduces the number of development loops and thereby the development time.
The Paper describes the tasks, the used tools and the results of the development process for the novel axial fan concept. As a result of the revised fan concept and the use of parametric optimization, the new fan has a higher efficiency than common axial fans, a steeper pressure characteristic with higher stall margin, a good noise behavior, less icing on the fan blades in evaporator applications and a higher throw distance. In addition to that, this fan has less increase of noise than typical axial fans, when it is used in applications with disturbed, highly turbulent inflow conditions.