Additively controlled surface roughness for designed performance

Abstract

A process for additively controlled surface features of a gas turbine engine casing. The process comprises forming the casing having an inner surface and an outer surface opposite the inner surface; forming a surface feature on the casing proximate the inner surface, wherein the surface feature comprises a structure on the inner surface configured to align or misalign with respect to a flow direction of a working fluid in a flow path of the casing.

Claims

1. A casing with surface features for an attritable gas turbine engine comprising: a flow passage defined within said casing of the attritable gas turbine engine; the flow passage comprising an exterior portion and an interior portion opposite said exterior portion; and the surface features being formed in said flow passage on an inner surface of said interior portion, wherein said surface features comprise a structure formed unitary with the interior portion configured to reduce a flow resistance of a fluid flow, wherein said surface features are selected from the group consisting of dimples, ridges, nubs, lumps, protuberances, furrows, voids, gaps, fissures, hollows, trenches, pockets, bumps, lumps, knobs, projections, protrusions, prominences, outcrops, outgrowths, juts, jags, and snags.

2. The casing with surface features according to claim 1, wherein said surface features comprise the same material composition as said casing.

3. The casing with surface features according to claim 1, wherein said surface features are configured to provide a predetermined resistance to a flow of a working fluid.

4. A casing with surface features for an attritable gas turbine engine comprising: a flow passage defined within said casing of the attritable gas turbine engine; the flow passage comprising an exterior portion and an interior portion opposite said exterior portion; and the surface features being formed in said flow passage on an inner surface of said interior portion, wherein said surface features comprise a structure formed unitary with the interior portion configured to reduce a flow resistance of a fluid flow, wherein said surface features comprise a plurality of scallop shapes.

5. The casing with surface features according to claim 4, wherein said surface features comprise the same material composition as said casing.

6. The casing with surface features according to claim 4, wherein said surface features are configured to provide a predetermined resistance to a flow of a working fluid.

7. The casing with surface features according to claim 4, wherein said plurality of scallop shapes include curved edges oriented downstream relative to a flow direction of a working fluid in the flow passage of said casing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 a cross-sectional schematic representation of sections of a turbine engine.

(2) FIG. 2 is a schematic representation of a cross section of an exemplary flow passage.

(3) FIG. 3 is a schematic representation of a cross section of an exemplary flow passage.

(4) FIG. 4 is a schematic representation of a cross section of an exemplary flow passage.

(5) FIG. 5 is a schematic representation of a cross section of an exemplary flow passage.

DETAILED DESCRIPTION

(6) Referring now to FIG. 1, through FIG. 5, there is illustrated a section of a gas turbine engine 10, such as a compressor stage and a turbine stage. The turbine engine section 10 can include a casing 12. The casing 12 includes flow passages 14 that have an interior portion 16 opposite an exterior portion 18. The interior portion 16 has an inner surface 20 that is opposite an outer surface 22 formed in the exterior portion 18. In an exemplary embodiment, the flow passage 14 has a thickness T that spans from the outer surface 22 to the inner surface 20.

(7) The flow passage 14 can define a flow path that the working fluid 26 utilizes during the function of the gas turbine engine 10. In another exemplary embodiment, in addition to the casing 12, the flow passages 14 can be associated with additional components and sections of the gas turbine engine 10. The flow passage 14 is shown as a cylinder for descriptive purposes, however, any variety of shapes can form the flow passage 14 within the gas turbine engine 10.

(8) The flow passage 14 includes a surface roughness or simply a surface feature 28 formed on the inner surface 20. The surface feature 28 can be formed from the same material as the casing 12. The surface feature 28 aligns with a flow direction 30 of the working fluid 26 in the flow path 24. The surface feature 28 can be misaligned with the flow direction 30, such as at different angles with respect to the flow direction 30, in order to induce a predetermined resistance to flow of the working fluid 26. The surface feature 28 is intentionally formed to enhance the flow of the working fluid 26 through the flow passages 14. The surface feature 28 provides the proper fluid flow characteristics related to surface friction, drag and flow losses along the inner surface 20.

(9) The surface feature 28 is shown as scallop shaped formations 32 on the inner surface 20. The scallop formations are aligned with the flow direction 30 such that the scallop features 32 lay out along the inner surface 20 with the curved edges downstream relative to the flow direction 30. The surface features 28 resemble surface of the scales of fish and snakes that align in a common direction. The surface features 28 provide less resistance to the flow of the working fluid 26. In other exemplary embodiments, as seen in FIGS. 3, 4, 5, the surface features 28 can be oriented to misalign with the flow direction 30 in order to produce a predetermined flow resistance.

(10) The surface feature 28 is not limited to scallop formations 32. In exemplary embodiments, the surface feature 28 can include dimples, ridges, nubs, lumps, protuberances, furrows, voids, gaps, fissures, hollows, trenches, pockets, bumps, lumps, knobs, projections, protrusions, prominences, outcrops, outgrowths, juts, jags, snags and the like. In an exemplary embodiment, the surface feature 28 can be formed extending from the inner surface 20 substantially perpendicular to the flow direction 30. In an exemplary embodiment, the surface feature 28 can be formed extending from the inner surface 20 at an angle with respect to the flow direction 30.

(11) The surface feature 28 can be formed along with the casing 12 by use of additive manufacturing. In an exemplary embodiment, the surface feature 28 can be formed utilizing model-based additive manufacturing techniques. Those exemplary additive manufacturing techniques can include changing process parameters to produce the surface feature 28 within the casing 12 proximate the inner surface 20.

(12) An exemplary additive manufacturing technique illustrated at FIG. 2 can include utilizing directed energy deposition. An energy source 36 can provide directed energy capable of melting a feed material 38 from a material feeder 40. The energy source 36 can be a laser. The energy source 36 melts the feed material 38 into a melt pool 42. The energy source 36 is directed such that the melt pool 42 is influenced in the direction parallel with the flow direction 30. In directing the melt pool 42 along the flow direction 30 the cooled melt pool 42 forms the scallop formations 32 aligned/oriented downstream with the flow direction 30. In other exemplary embodiments, the directed energy 36 can be utilized to form other surface feature 28 shapes as disclosed above. For example, the energy source 36 direction can be altered to make tracks that are streamlined along the flow direction 30 and follow the inner surface 20 of the flow passage 14.

(13) In another exemplary embodiment, an additive manufacturing technique can include forming the additive material in conical shapes with a rotary motion to form a series of hoops, built-up over each other. The resulting surface feature 28 can include a series of ridges and valleys that reduce the flow resistance along the flow path 24. In another embodiment, the additive manufacturing technique can include a tool head 44 that can machine the inner surface 20 and feed material to the application site.

(14) In an exemplary embodiment, the surface feature 28 can be formed in-situ, on final pass and the like. Additive manufacturing of the surface feature can be done employing direct energy deposition or laser powder bed fusion. Using direct energy deposition, it is possible to build sections of the structure in dissimilar metals which are weldable. A laser powder bed approach would result in the surface feature, integrated with the wall casings being built at the same time. In another exemplary embodiment, one can utilize an L-PBF process, where the part is built and material is added one layer at a time, the laser passes and resultant molten material scallops can be controlled to travel and align with the flow direction and be configured for reducing pressure drop. The scallops if aligned perpendicular to the flow direction would create vortices that would increase pressure drop or loss. By controlling the scanning direction of the laser, the surface roughness can be controlled to provide designed performance enhancement for the gas turbine engine.

(15) The surface feature provides the advantage of a reduction in pressure drop and improvement in the gas turbine engine performance.

(16) The process for additively controlled surface features provides the advantage of a reduction or avoidance of post additive build surface roughness processing techniques resulting in cost reductions.

(17) The process for additively controlled surface features provides the advantage of enabling utilization of same component geometry for designed performance based on application need.

(18) The process for additively controlled surface features provides the advantage of utilization of coarser additive techniques (e.g. DED Vs L-PBF process) without increasing the requirement on post processing techniques to reduce surface roughness.

(19) There has been provided a process for additively controlled surface features on internal flow passages for attritable engine applications. While the process for additively controlled surface features on internal flow passages has been described in the context of specific embodiments thereof, other unforeseen alternatives, modifications, and variations may become apparent to those skilled in the art having read the foregoing description. Accordingly, it is intended to embrace those alternatives, modifications, and variations which fall within the broad scope of the appended claims.