Manufacturing of a high-temperature resistojet heat exchanger by selective laser melting

Abstract

The paper presents the design, manufacturing and postproduction analysis of a novel high-temperature spacecraft resistojet heat exchanger manufactured through selective laser melting to validate the manufacturing approach. The work includes the analysis of critical features of a heat exchanger with integrated converging-diverging nozzle as a single piece element. The metrology of the component is investigated using optical analysis and profilometry to verify the integrity of components. A novel process of high-resolution micro-Computed Tomography (CT) is applied as a tool for volumetric non-destructive inspection and conformity since the complex geometry of the thruster does not allow internal examination. The CT volume data is utilised to determine a surface mesh on which a novel perform coordinate measurement technique is applied for nominal/actual comparison and wall thickness analysis. A thin-wall concentric tubular heat exchanger design is determined to meet dimensional accuracy requirements through nominal/actual comparison analysis. The work indicates the production of fine structures with feature sizes below 200 μm in 316L stainless via selective laser melting is feasible and opens up new possibilities for the future developments in multiple industries.

Powder-Based 3D Printing for the Fabrication of Device with Micro and Mesoscale Features

“…Figure 11 d is another example of SLM 3D-printed high-temperature aerospace resistojet heat exchanger with varying wall thickness ranging from 660 μm to 800 μm. However, the minimum wall thickness of supporting structures was measured to be 100 μm [ 233 ].…”

“…Reproduced with permission from [ 121 ]; ( d ) high-temperature aerospace resistojet heat exchanger 3D-printed by SLM 3D-printing process. Reproduced with permission from [ 233 ].…”

Validation of an additively manufactured resistojet through experimental and computational analysis

“…The current state of the art xenon resistojet has shown specific impulse (ISP) with xenon propellant up to 48 s utilised for small spacecraft below 500 kg [1][2][3]. Such performance can result in either propellant mass savings or increased capability with respect to cold gas thrusters [4]. The primary application for a high performance resistojet is for primary propulsion on small satellite platforms [5] with an emerging possibility of utilisation as a secondary propulsion system for all-electric telecommunication satellite platforms, where a complement of thrusters would form a reaction control system (RCS) using xenon as a common propellant in combination with a primary electric propulsion system [6].…”

“…A high-temperature resistojet concept, named the Super-High Temperature Additive Resistojet (STAR), under development at the University of Southampton [4] has a target ISP > 80 s, with an overall thruster efficiency of > 60%. The primary technology lies in the multifunctional heat exchanger, which is 3D printed via Selective Laser Melting (SLM).…”

3D Printing of Ion Optics for Electric Propulsion

“…Electric propulsion can also benefit from the advantages of SLM, as shown by Romei et al [20], when they selectively laser melted a stainless-steel resistojet heat exchanger. However, one of the big challenges for the application of SLM to the fabrication of electric thrusters' components is the development of new materials for this process.…”