Numerical Simulation of Streamer Development Process in N2/H2 Environment at Elevated Temperature

In this article, a two-dimensional (2-D) axisymmetric fluid model is built to investigate the streamer development characteristics, as well as the distribution time of each reactive components with pure N2, pure H2, and mixed gases of 50% N2 and 50% H2 at lower voltage and elevated temperature. The results indicate that in terms of thermal breakdown, the insulating properties of pure N2 are stronger than that of pure H2. Under the influence of high temperature, the shape of the ionization rate distribution is no longer a slender wave shape but more spread. In addition, a new ionization area will be formed near the rod electrode, and finally, the ionization region near the rod electrode will merge with the ionization wave head with the increase in temperature. For the mixed gas of 50% N2 and 50% H2, it will dissociate into atoms and recombine under the action of high temperature to form molecules containing both nitrogen and hydrogen elements, such as NH3. NH3 is an electronegative gas, which will greatly enhance the thermal breakdown performance of the mixed gas and makes its dielectric strength second only to pure N2. Therefore, it can be speculated that appropriately increasing the proportion of H2 in the mixed gas will improve both the arc extinguishing ability and the postarc thermal breakdown performance, which has been proven by experiments considering that the arc extinguishing ability of H2 is stronger than that of N2.