Citation: Szelka, M.; Drwi ˛ ega, A.; Tokarczyk, J.; Szygula, M.; Szewerda, K.; Bana´ s, M.; Kolodziejczyk, K.; K˛ edzia, K. Study of the Blade Shape Impact on the Improvement of Fan Efficiency Based on State-of-the-Art Prototyping Methods. Energies 2023, 16, 542. https://doi.org/10.3390/ en16010542 Academic Editor: Frede Blaabjerg Received: 21 November 2022 Revised: 29 December 2022 Accepted: 30 December 2022 Published: 3 January 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). energies Article Study of the Blade Shape Impact on the Improvement of Fan Efficiency Based on State-of-the-Art Prototyping Methods Michal Szelka 1, * , Andrzej Drwi ˛ ega 1 , Jaroslaw Tokarczyk 1 , Marek Szygula 1 , Kamil Szewerda 1 , Marian Bana´ s 2 , Krzysztof Kolodziejczyk 2 and Krzysztof K ˛ edzia 3 1 KOMAG, Institute of Mining Technology, Pszczy´ nska Str. 37, 44-101 Gliwice, Poland 2 Department of Power Systems and Environmental Protection, Faculty of Mechanical Engineering and Robotics, AGH University of Science and Technology, Mickiewicz 30 Av., 30-059 Krakow, Poland 3 Department of Technical Systems Operation and Maintenance, Faculty of Mechanical Engineering, Wroclaw University of Science and Technology, Wyspianskiego Str. 27, 50-370 Wroclaw, Poland * Correspondence: mszelka@komag.eu Abstract: The article discusses the process of designing and testing as well as their results, carried out in order to increase the efficiency of axial fans, implemented as part of the European project INESI. Modifications of existing solutions based on rapid prototyping methods were presented. Scanning, FEM and CFD numerical calculations and 3D printing were used for that purpose. Rapid prototyping involved the use of a steel blade base and 3D-printed complex aerodynamic shapes that were bonded to create completely new blades. After their installation on the new rotor, enabling the angle of attack adjusting, a number of verifying tests of the fan were carried out. The solution was successfully tested and the results are discussed in the article. Keywords: axial fan; ventilation; efficiency; rapid prototyping; CFD; FEM; 3D printing 1. Introduction Axial fans belong to the group of rotating machines, which, using the energy supplied from the outside, compress and convey vapours and gases [1,2]. They are widely used in mechanical ventilation, air conditioning or dust extraction. The fan rotor is the component that transfers energy to the fluid. The component transferring energy to the pumped medium is a fan rotor. Efficiency, compression ratio and efficiency of the entire device (fan) depends on it. In the case of mining ventubes (air ducts), the geometric features of each blade included in the rotor blade rim result from the used production technology [3–6]. Until now, the main criterion with regard to the shape of the blade was the cost of its manufacturing, which is why in most cases they were made of a bent steel sheet profile with a constant thickness along its length. One of the few cases when another type of blade is used in underground mining is the use of materials such as Itamid or duralumin. These materials enabled the use of profiles of a more complex shape, modelled on the NACA (National Advisory Committee for Aeronautics) type profile, allowing for an increase in efficiency of 5–10%, but it is associated with the need to make expensive casting moulds, and the precision workmanship could be verified only after manufacturing of the first blades and the rotor prototype [7]. The traditional, cheaper method of manufacturing blades from bent steel sheet allows achieving satisfactory efficiencies of 60–70 (%) and is still widely used. Currently, as a result of the growing environmental awareness, as well as in connection with the drastic increases in electricity prices, solutions are being sought to meet the increasing expectations of users. The possible effects of improving the efficiency of the fans were tested in two stages. In the first stage, it was decided to improve the shape of the rotor blades made of Itamid [8,9]. As mentioned earlier, blades made of this material have some features of state-of-the-art profiles, thanks to which they have higher efficiency compared to steel blades. Energies 2023, 16, 542. https://doi.org/10.3390/en16010542 https://www.mdpi.com/journal/energies