Plume–Plume and Plume–Surface Interactions of Micronozzle Clusters in Vacuum

Plume flow features and performance characteristics of micronozzles arranged in a cluster configuration operating under vacuum exit conditions are analyzed utilizing the direct simulation Monte Carlo (DSMC) method. A comparison of the plume behavior of single bell-shaped and conical nozzles is carried out to establish a baseline for evaluating cluster configurations of two, three, four, and five nozzles. Simulations focused on understanding plume–plume interactions and plume–surface interactions, where cluster spacings are varied. The comparison between bell and conical nozzles shows that the conical nozzle, with greater acceleration in the divergent section, achieves higher Mach numbers and outperforms the bell nozzle. As more nozzles are clustered, plume interactions increase, reducing performance and raising density and temperature along the plume centerline. An impingement surface modifies the plume structure, with a more well-defined plume observed in the presence of a surface. A cluster configuration results in fewer backflow effects than operating a single thruster that generates a similar thrust level. Increasing nozzle pitch in a cluster configuration minimally impacts backflow but significantly reduces impingement pressure and heat flux. The findings contribute to a better understanding of the performance of microthruster clusters, a crucial consideration for satellite propulsion systems.