Numerical analysis of inlet flows in an atmosphere-breathing electric propulsion system
Abstract
<p indent="0mm">A comprehensive numerical study was conducted using the direct simulation Monte Carlo (DSMC) method for investigating the gas flows inside the inlet of an atmosphere-breathing electric propulsion (ABEP) system. This was done to obtain various inlet designs for the ABEP system operating in the upper atmosphere ranging from 120 to <sc>300 km.</sc> The primary objective was to gain insights into the gas-pressure and mass-flux distributions, analyze the effect of operation altitudes on inlet performances, and assess the rationality of the free molecular flow (FMF) assumption. The results showed that gas pressure decreased with increasing altitude, indicating a weaker compression performance of the inlet at higher altitudes. Thus, future research must comprehensively analyze the compression performance of the inlet when the ABEP system operates at higher altitudes. Further, the dimensionless mass flux decreased in the central region of the compression section at higher altitudes but increased in the center of the ionization section; this finding can be attributed to the weakened collisions between gas molecules. At an altitude of <sc>~120 km,</sc> collisions between gas molecules played an important role: there was a large discrepancy in the gas-pressure and mass-flux determination results based on the FMF assumption and standard DSMC method. However, for altitudes <sc>>180 km,</sc> gas flows in the inlet were characterized by free molecular flows. The results based on the FMF assumption were consistent with those of the standard DSMC method, indicating the rationality of the FMF assumption at these altitudes.</p>
