Selection of Materials for Fan Blades: A Comprehensive Guide
The most prestigious event in this sector worldwide, the annual Cooling Tower Institute (CTI) conference, took place in Houston, TX, from February 4th to 8th, 2024.
FanTR was present not only as an exhibitor of products and solutions for cooling towers but also as a speaker.
Check out the publication about the event at: 2024 CTI ANNUAL CONFERENCE AND CTI EXPO.
Selection of Materials for Fan Blades: A Comprehensive Guide
Marcelo Carvalho, Commercial Director, and Ricardo Costa, R&D Coordinator, presented in an educational seminar titled: "Selection of Materials for Fan Blades: A Comprehensive Guide"
During this participation, both speakers shared valuable insights, which are presented in this article.
Check below:
Picture: CTI 2024 Event
During the presentation, FanTR sought to clarify the connection between the aerodynamic performance and the structural performance of large-scale axial fans, as well as the relationship between the materials and the manufacturing processes of the blades.
In addition, important points in the choice of fasteners were addressed, with emphasis on those applied in the fan hubs.
It was possible to elucidate that the analysis of mechanical properties is just one of the characteristics for defining the best material. The design possibilities associated with each material and manufacturing process, which define the freedom to create complex aerodynamic geometries, were the central theme of the presentation.
As an example, some possible geometries of transition between the blade and the fan hubs were presented:
Figure 1: Abrupt Transition Figure 2: Smooth Transition
Note that in the first figure, the transition between the blade and the hub is made abruptly, resulting in better aerodynamic conditions in the root region of the blade. The second figure details a smooth transition which, despite being structurally more conservative, can lead to aerodynamic recirculation problems in the root region, and consequently, lower fan efficiency.
FanTR explained the origin of this aerodynamic condition and emphasized that the adoption of a seal disk, as shown in figure 2, can minimize the problem. It also pointed out that not every fan requires a seal disk. If the manufacturer can, for instance, increase the thickness of the material at the root of the blade as a means of dissipating mechanical stresses, an abrupt transition can be adopted.
In this case, the recirculation condition at the root is resolved and better efficiencies can be achieved. However, this is a condition that not all materials/processes can provide.
Analysis of Resources for Aerodynamic Projects
Several aerodynamic resources available for efficient fan blade design were presented. Among them, we can highlight the variation of the chord (measure of the length of the aerodynamic profile) between the root and the tip, and the twist of the blade.