Figure 5 shows the example flow for
an integrally vaned stator with a shroud for the companion rotor. It illustrates the process starting with a 3D CAD model of the part, which is used to generate the CAD model of the mold. This model is then used to 3D-print the ceramic mold, which is then followed by the casting steps in the foundry. The introduction of ceramic
additive manufacturing has enabled the reduction in the cost and lead time in making traditional
castings. More
importantly, the 3D-printing of ceramic molds and cores has enabled the low- cost design and production of more advanced castings for turbine engines [5].
2.1 Integral-Shroud-Diffuser- Exit-Shroud (ISDES) The production of low-cost and high- performing small turbine engines is driven by component part size, weight, count, and thermal capabilities. desire to reduce part count starts
The at
the compressor section where the centrifugal air flow must be directed into the compressor section with a diffuser and a set of exit guide vanes. Figure 6 shows the cross section of a turbojet engine with the grayed area showing the portion of the engine that ordinarily would consist of multiple parts. As part of the solution, the Renaissance Services team worked with AFRL to combine the functions of the diffuser, exit guide vanes, and shrouds into a single casting. Figure 7 shows the design of the ISDES with the left side depicting the finished part after machining.
Meanwhile the right side
shows a translucent version of the part, which highlights the two rows of airfoils. The first row is the diffuser while the second row are the exit guide vanes. The left side of Figure 8 shows the 3D-printed ceramic shell that was used to form the ISDES casting. The right side of the figure shows the resulting A356 aluminum casting produced by HTC Castings in New Carlisle, Ohio.
2.2 Cooled Integrally Vaned Stator (CIVS) The
production ® of airfoils with Figure 9: Cooled Integrally Vaned Stator (CIVS) with Cast-In Cooling Holes
Figure 10: Ceramic Core CAD Model and 3d-Printed Ceramic Core and Mold Used for CIVS
integral conformal cooling channels is one common way to improve the performance of turbine engines. However,
this typically involves very
complex castings with ceramic cores, and many post-processing steps such as laser drilling of the cooling holes. Thus, considerations for improving thermal capabilities can be cost prohibitive for small attritable and expendable engines. An opportunity recognized by the Renaissance Services team was the ability to 3D-print ceramic airfoil
molds with integral cores for the internal cooling channels; and include the production of the surface cooling holes within the casting process.
This
approach enables the production of an advanced cooled stator at a fraction of the cost of traditional methods. Figure 9 shows the 3D CAD model of the 6” diameter integrally vaned stator. The light blue shapes at the hub are the input cooling channels into the
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