# Numerical and Experimental Characterization of a Coanda-Type Industrial Air Amplifier
## 6 Conclusions  
The performance evaluation of an industrial air amplifier involved comprehensive experimental and numerical analyses. The findings reveal that while both the injected and entrained mass flows increased linearly with the total pressure at the injection line, they exhibited different trends. Consequently, the amplification factor eventually reaches saturation, showing no further improvement when subjected to high input mass flows. Similarly, increasing the Coanda nozzle gap of the primary flow results in a linear growth in entrained mass flow, but these gains are penalized with a rapid decrease in efficiency. Thicker injection gaps result in lower amplification factors. This should be taken into consideration when the industrial application of the air amplifier requires displacement of large mass flows. These results are consistent in both modes of operation of the device, with these being either aspirating or blowing (depending on how the air amplifier is connected to an upstream or downstream piping system). However, the amplification factor observed during the experimental characterization showed higher values when working in the blowing mode, specially for larger nozzle gap sizes. Scaling the air amplifier for greater total mass flows also led first to a saturating condition, followed by a decay in the air amplifier performance. By characterizing the aspect ratio defined by the internal diameter of the device and the clearance gap of the nozzle, how the total mass flows was observed, and the amplification factor reached a point beyond saturation, with a clear maximum, after which there was a significant decay in its values. This effect was also dependent on the nozzle gap size, with saturation occurring for higher values of the aspect ratio when thinner gaps were considered. An increase in volumetric mass flow was observed when the device was scaled, but it was more related to an increase in the outflow area rather than an increment on the flow velocity. As the flow entrainment is caused by the pressure drop caused by the flow displacement across the device, ultimately generated by the transfer of momentum from the annular jet towards the axis of symmetry, increasing the inner diameter would eventually produce a decay in the aforementioned effects. These results underscore the sensitivity of air amplifiers to operating conditions and emphasizes the importance of tailoring the setup and sizing of the device to meet specific technical requirements. Considering the rapid decay in performance as the injected high-pressure mass flow increased, it is crucial to carefully consider the energy balance required for operating air amplifiers. [PERSON] and [PERSON] formulated the research plan and conceptualized the analyses, with support from [PERSON]. The numerical analyses were carried out by [PERSON] and [PERSON] conducted a formal analysis of the numerical dataset, overseeing the employed methodology and managing resources, while [PERSON] implemented and developed the validation, calculation, and interpretation of numerical results. The experimental studies were executed by [PERSON] and [PERSON], who equally contributed to the preparation and supervision of model manufacturing, conceptualization of the employed methodology, and data acquisition. [PERSON] obtained the financial support for the project leading to this publication. [PERSON] took charge of the original draft of the manuscript, with all authors participating in the final review and editing process. All authors have read and agreed to the published version of the manuscript. This project has received funding from Airbus Operations Limited under the CDTI PTA (Programa Tecnologico Aeronautico) 2021 program under grant agreement PTAG-20211002: _Plan Tecnologico Aeronautico ZERO (PTA_ZERO)_. Not applicable. The data presented in this study are available on request from the corresponding author.