Performance instability of EHD pump caused by turbulent flow

Electrohydrodynamic (EHD) pumps are attracting attention as next-generation pumps that are quiet, lightweight, and flexible. However, EHD pumps often have the problem of unstable output, which is one of the issues that must be overcome for practical use. There are various possible causes of instability, but in this paper, we focus on fluid dynamic instability and measure the pressure distribution inside the pump. In the experiment, manometers were attached to the pump to measure the pressure distribution from the liquid level, and at the same time, the current between the electrodes was measured to monitor whether an electrochemical reaction was occurring. As a result, we found that even when using the same pump design, applying the same voltage, and freshening the working fluid, the output flow rate varied from trial to trial. We also found that the output instability reflects the irregularity of the pressure distribution. Based on the observations, we discussed the relationship between the flow in the pump and its performance using a simple phenomenological model. The discussion raises the possibility that external loads, which have not previously been given much importance, may have a significant impact on pump stability. This shows that in the practical application of EHD pumps, it is necessary to carefully design not only the pump itself but also the entire flow system.