Fuel Thermal Management and Injector Part Design for LPBF Manufacturing

Kurzfassung

Additive manufacturing (AM) methods such as laser powder bed fusion (LPBF) are particularly attractive methods for manufacturing aero-engine burners as they allow for a complex design with well-tailored features at reasonable production costs. Unfavorable is still the lower precision in terms of geometrical accuracy and surface roughness compared to classical machining, especially if surfaces are oriented in unfavorable orientations. With regard to coke formation and the possibility of fuel line blockage due to too small cross-sectional areas, these drawbacks raise the question how fuel lines may be manufactured by AM and how AM affects the propensity of coke formation. In this study, the geometrical accuracy of LPBF manufactured parts built in small inclination angles to the working bed with “standard parameters” and well-adapted parameters is examined. For further improvement, two shape adjustment strategies are proposed and validated. Regarding the risk of coke formation, deposition rates on LPBF manufactured parts as-built and postprocessed with chemical etching are evaluated. It is shown that an optimized set of machining parameters increases the geometrical precision substantially, and the adjustment of the shape helps to meet the desired cross-sectional areas. Due to the increased roughness of LPBF manufactured parts, the evaluated coke deposition rates exceed the rates measured on classical machined parts by an order of magnitude. As presented, chemical etching the parts is an effective measure against coke deposition since the deposition rates descend to less than the half.