# Experimental Study on Anti-Icing Performance of NS-DBD Plasma Actuator
## 3 Experimental Results
### Thermal Properties  
With respect to the thermal effect of dielectric barrier discharge, [PERSON] et al. [33] revealed that the gas heating of AC-DBD is caused by electron elastic collisions, rotational and vibrational excitation,  
Figure 6: Discharge morphology of NS-DBD: (**a**) LV-HF discharge without impingement from supercooled water droplets; (**b**) HV-LF discharge without impingement from supercooled water droplets; (**c**) LV-HF discharge with impingement from supercooled water droplets; (**d**) LV-HF discharge with impingement from supercooled water droplets. Figure 7: Voltage-current waveforms of NS-DBD with two different discharge conditions: (**a**) LV-HF discharge; (**b**) HV-LF discharge. ion-neutral molecule collisions, and the thermal energy transferred from electrons to neutral particles. For NS-DBD, the gas breakdown voltage is apparently higher than the quasi-static breakdown voltage due to the fast rising time, which leads to a higher reduced electric field (E/N) at the moment of gas breakdown, and more energy being obtained by charged particles. As stated in reference [34; 35], the main processes of fast gas heating of NS-DBD can be classified as follow: (1) quenching of the N\({}_{2}\)(C\({}^{3}\)\(\prod_{\mathrm{u}}\)) states by oxygen; (2) quenching of the N\({}_{2}\)(B\({}^{3}\)\(\prod_{\mathrm{g}}\)) states by oxygen; (3) reactions involving charged particles; (4) dissociation of N\({}_{2}\) molecules by electron impact, followed by quenching of N(\({}^{2}\)D) atoms; (5) quenching of excited O(1D) atoms by nitrogen; (6) dissociation of O\({}_{2}\) molecules by electron impact, and (7) quenching of the excited molecules N\({}_{2}\)(A\({}^{3}\)\(\sum_{\mathrm{u}}^{+}\)) and N2(a\({}^{\prime 1}\)\(\sum_{\mathrm{u}}^{-}\)) by oxygen. [PERSON] et al. proposed that the heating energy of gas can be divided into two parts, which can be defined as:  
\[P_{heat}=P_{ion}+P_{qch} \tag{2}\]  
where \(P_{ion}\) means the power released through collisions between charged particles and neutrals, and \(P_{qch}\) is the energy released through the channel of quenching between excited molecules and neutrals or atoms [24]. Except for the gas heating, as with AC-DBD, the heating of the dielectric surface is also an essential part of the total input energy [30]. As shown in Figure 8, the measurement window of the IR thermal imaging system is in the red dotted line box. A rectangular coordinate system is established in the infrared temperature measurement area. The span direction of the airfoil model is set as the X-axis, while the chordwise direction is the Y-axis; the origin is set at the leading edge. In order to explore the thermal characteristics of the NS-DBD plasma actuator, the time variations of surface temperature under two different environments were captured: (1) room temperature (25 \({}^{\circ}\)C) and normal atmospheric pressure, (2) cold airflow condition of U = 65 m/s, T = -10 \({}^{\circ}\)C, LWC = 0 g/m\({}^{3}\) (without turning on the spray system). The voltage waveform applied to the actuator is the same as that described in the previous section. The NS-DBD plasma actuator quickly suffers damage at room temperature due to the high temperature of the dielectric barrier. Therefore, the surface temperature distribution of the actuator after being ignited for 10 s, as shown in Figure 9, is selected for analysis. It can be clearly seen that the temperature rise is mainly concentrated on the discharge region. With the same power consumption, the surface temperature of the HF-LV discharge is higher than that of the HV-LF discharge. The temperature peak was observed at the exposed electrode's edge, which is consistent  
Figure 8: Measurement window of the IR thermal imaging system. with the result reported in reference [36]. Moreover, it's probably worth pointing out that disparate temperature distribution near the location of Y = 40 mm corresponds to the discharge area, which is attributed to the effect of surface potential mentioned in the previous section.