Plastron recovery on hydrophobic surfaces with electrolytic substrates under hydrostatic pressure and turbulent flow conditions

Hydrophobic surfaces with integrated electrolytic substrates, denoted as ES-HSs, are fabricated to actively maintain and recover plastrons under hydrostatic pressure and turbulent flow conditions. The blade-coating method and molding processes are applied to prepare hydrophobic surfaces featuring trapezoidal grooves with underlying electrolytic substrates made of Polydimethylsiloxane and Carbon powders. ES-HSs with groove depth-to-width ratios ranging from 0.23 to 2.69 are tested in the hydrostatic pressure and turbulent flow experiments. The plastron on the ES-HSs can be successfully recovered both in complete and partial wet conditions at different hydrostatic pressures (i.e., gage pressure 0.1–40 kPa). The visualization of the plastron recovery process and measurement of electrochemical parameters have shown that the plastron replenishment can automatically start and stop without external control, which fits perfectly with the theoretical analysis. The successful plastron recovery and maintenance are confirmed in the recirculating turbulent seawater tunnel at Reynolds number up to 1.65 × 106 (i.e., U∞ = 2.3 m/s) while the consumption of power density is only as low as 133.3 W/m2. This study provides the first systematic investigation of plastron recovery mechanisms in hydrostatic and turbulent conditions, offering a universal framework for the design of persistent plastrons in marine applications.