Modelling and simulation of atmosphere-breathing electric propulsion intakes via direct simulation Monte Carlo

The Air-Breathing Ion Engine (ABIE) is an electric propulsion system capable of compensating for drag at low altitudes by ingesting the surrounding atmospheric particles to be utilized as propellant. The current state of the art of the ABIE performance is evaluated via Direct Simulation Monte Carlo (DSMC), due to the rarefied nature of the atmosphere in Very-Low Earth Orbit (VLEO). Nevertheless, the scarce availability of relevant simulation methodologies in the literature limits the repeatability of such numerical studies. Therefore, this paper proposes an independent methodology applicable to the modelling and simulation of Atmosphere-Breathing Electric Propulsion (ABEP) intakes that aims to validate the ABIE DSMC results retrieved from the literature. This is achieved by investigating the ABIE intake collection efficiency and compression ratio through the open-source solver dsmcFoam+ and by assessing the results against the available RARAC-3D DSMC data. First, the variation of grid transparency is discussed and compared between both solvers, yielding a mean percentage error of $$2.97\%$$ 2.97 % for the compression ratio and $$2.06\%$$ 2.06 % for the collection efficiency. Second, the absence of intermolecular collisions is verified for which errors of $$1.61\%$$ 1.61 % for collection efficiency and $$3.49\%$$ 3.49 % for compression ratio are observed. Then, the variation of flow incidence angle is simulated between $$0^{\circ }$$ 0 ∘ and $$15^{\circ }$$ 15 ∘ , yielding differences lower than $$1.80\%$$ 1.80 % . Consecutively, the intake aspect ratio is varied between 10 and 40, for which a maximum discrepancy of $$1.83\%$$ 1.83 % is measured and, finally, the drag coefficient of the intake is obtained in dsmcFoam+ to define the power density requirements.