Ionic wind induced by elementary needle-ring structure under varying temperature-humidity conditions

Ionic wind is an emerging technique for air supply and heat-transfer enhancement, but it is affected by the ambient temperature and humidity significantly. Current studies mainly focus on the discharge characteristics, whereas research on the coupling mechanism of discharge and ionic-wind output under varying temperature-humidity conditions is quite scarce. In this study, a needle-ring ionic wind generator is used to clarify the variations and their internal correlation mechanisms of the transient, volt-ampere, and wind-velocity output characteristics of discharging in varying temperature-humidity environments. The results indicate humidity reduces the Trichel-pulse frequency, contracts the frequency-fluctuation range, and increases the pulse amplitudes and the transition voltage of Trichel pulse to pulse-free glow. The vapor condensation on the emitter produces the opposite effect. The above two factors are in constant competition with each other, affecting the discharging, but both cause the pulse amplitude non-uniformity to increase. Temperature plays a role in regulating the relative strength of effects of humidity and vapor condensation. As humidity increases, the ionic wind velocity remains relatively stable when the relative humidity is below 40 %. However, it gradually rises once the relative humidity exceeds 40 %. The maximum increase in wind velocity reaches 0.34 m⋅s⁻¹ as the relative humidity rises from 60 % to 95 %. Notably, higher temperatures reduce the rate of increase in wind velocity with rising humidity. This study can be a guide for designing ionic wind devices operating under varying ambient conditions.