An in-silico proof-of-concept of electrohydrodynamic air amplifier for low-energy airflow generation
Keywords:Air propulsion, CFD, Electrohydrodynamics, Corona discharge, Ionic wind, Coanda effect
Using electrohydrodynamics (EHD) we can generate airflow without impellers or other moving parts. This airflow, or ionic wind, is invoked by corona discharge with the subsequent acceleration of electrically charged air molecules in a strong electric field. However, EHD-induced air propulsion is considered inefficient due to its low electrical to mechanical energy conversion rate compared to conventional fans. This study aims at improving the energy efficiency expressed in flow rate to electrical power input of EHD-based airflow devices. A novel bladeless air propulsion device is proposed that combines ionic wind with air amplification based on the Coanda phenomenon to amplify EHD-generated flow rates. We assess the performance of the bladeless air propulsion device as an alternative technology to conventional fans by investigating the fluid dynamics, electrostatics, and energy consumption. We demonstrate the proof-of-concept with an innovative fully-coupled simulation approach for corona discharge and EHD modeling. We explore different design parameters on the conceptual EHD air amplifier, such as the electric potential (10-30 kV) of the discharge electrode, the electrode spacing (5-25 mm), the channel height (30-150 mm). The studies are performed on a 2D constrained channel flow and a 2D-axisymmetric open space design, respectively. In order to quantify the benefit of air amplification on EHD, the results are benchmarked to a regular EHD setup without amplifying vane as well as to a comparable commercial axial fan. Regarding the energy efficiency measure of flow rate per electric power input, the EHD air amplifier in the constrained flow configuration improves the energy efficiency by 59% compared to regular EHD and by 48% compared to the axial fan. Amplification factors of 16.5 to 19 are achieved for the constrained configuration and 5.5 to 6.4 for the open space configuration. These results show that EHD air amplification is a promising way to generate airflow with low energy consumption. By air amplification, we can increase the airflow rates of EHD with a factor 10.
Copyright (c) 2022 Donato Rubinetti, Kamran Iranshashi, Daniel Onwude, Lei Xie, Bart Nicolai, Thijs Defraeye
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