Abstract
The mechanical performance and manufacturability of Laser Powder Bed Fusion (L-PBF) components are increasingly understood; however, an unresolved challenge of significance to L-PBF application is associated with the as-manufactured surface. The surface roughness induced in L-PBF additive manufacturing is generally much higher – in magnitudes of 10-12X – than that for conventional subtractive manufacturing processes and has design implications that need to be considered regarding increased convective heat transfer and pressure drop characteristics. More work is needed to understand these effects on thermal fluid performance, especially for precision liquid rocket engine components. A comprehensive literature review on metal additive manufacturing processes for the launch vehicle industry with a focus on L-PBF has been conducted in this study, as well as development of a computational model to assist propulsion engineers, researchers, and aerospace professionals understand design considerations when selecting metal additive manufacturing solutions for injectors and cooling channels within combustion chambers. This model utilizes Computational Fluid Dynamics (CFD) to investigate surface roughness effects on an orifice with a fixed short length/diameter (L/D) to represent an injector plate orifice and a fixed long L/D to represent a cooling channel in a regeneratively cooled rocket engine. The goal of this research is to contribute to the accessibility of space operations by reducing the cost-to-orbit via more efficient and economical manufacturing processes such as L-PBF to print metal rocket components.