# Icing Mitigation by MEMS-Fabricated Surface Dielectric Barrier Discharge
## 4 Icing Experiment
### Anti-Icing Results  
Images of the SDBDs after the operation in the iCORE with the parameters given by Table 1 are shown in Figure 10. The intention was to operate all samples with a comparable  
Figure 9: The iCORE, the used icing and contamination research test facility. The left side depicts the whole setup with the air acceleration and cooling system. The right shows an image of the test section with a SDBD sample mounted to an airfoil. power consumption. Since the power measurement was not available in the icing wind tunnel for the zirconia SDBD, the power consumption was estimated from subjective perception of discharge intensity. Therefore, the zirconia SDBD was operated at significantly lower voltages (2 kV\({}_{\text{rms}}\)) in comparison to the glass and the FR-4 samples (5.4 kV\({}_{\text{rms}}\)). Nevertheless, this low operation voltage corresponds to a power consumption of 21 W m\({}^{-1}\) which is about three times as high as the operation power of the 500 \(\upmu\)m thick SDBDs (7.5 W m\({}^{-1}\) at 5.4 kV\({}_{\text{rms}}\) ). The voltage is indicated in Figures 7 and 8 by dashed vertical lines. See also the red triangles for the power values measured during the iCORE experiment. The obtained values are slightly lower compared to the measurements at ambient air. This small difference can be attributed to the higher humidity of the saturated air in the iCORE according to [34,48], however, it is still in the uncertainty range of the electrical measurements. At the given test condition, which is referred to as rime ice condition, supercooled droplets in the air flow impact on the sample surface and freeze instantly. This mechanism leads to the steady growth of an ice column against the wind direction [21,49]. The likelihood of a supercooled water droplet adhering to the surface, and thus the severity of ice formation, depends on environmental conditions, surface wettability, and surface roughness [50,51]. Due to the hydrophilic properties of the zirconia ceramic, ice formed more rapidly on the reference area, so the duration of the experiment was shortened to 3 min. The growth of the ice column is seen much more pronounced on the zirconia surface then on the glass or the FR-4 after 5 min of operation. Note that the dark circle on the top of the reference area of the glass sample corresponds to a piezo element attached on the backside, which was not operating in this experiment. The SDBD area covered by the discharge is significantly less affected by the icing process or even completely free of ice in the case of the zirconia SDBD which proofs the SDBD anti-icing capability. For additional photos from the iCORE experiment see Supplementary S10. The FR-4 sample was exposed to a higher air speed, which might be a reason for the ice formation on the SDBD area. The ice accumulated parallel to the electrodes but with a certain distance to them. Supercooled water droplets stick to the 35 \(\upmu\)m high electrode and start to form an ice accretion growing towards the flow along the surface. After a significant ice accretion is formed in front of the electrodes, ice in close proximity to the electrode is melted away by the high temperature [23] of the electrode. The result is an ice accretion with a certain distance to the electrodes. In order to support the assumption of  
Figure 10: Images of the anti-icing experiment with the three studied materials taken with the machine vision camera from a top view during the anti-icing experiment at the times displayed in the individual lower left corners. The images below depict a magnification of the area marked in green. ice accretion initiation on the elevated electrodes, the area of the samples on the side of the high-voltage electrode was examined, see the excerpts on the bottom of Figure 10, which are magnification of the areas marked in green for all samples.