Patent Publication Number: US-11028725-B2

Title: Adaptive morphing engine geometry

Description:
BACKGROUND 
     The present disclosure is directed to an adaptive morphing engine geometry. Particularly, the disclosure includes an adaptive compliant skin for aerodynamic surfaces of gas turbine engines. The adaptive compliant skin can be configured as a morphing aerodynamic control surface geometry. 
     In order to improve the performance of a compressor, one or more of the stator stages may include variable stator vanes, or variable vanes, configured to be rotated about their longitudinal or radial axes. Such variable stator vanes generally permit compressor efficiency and operability to be enhanced by controlling the amount of air flowing into and through the compressor by varying the angle at which the stator vanes are oriented relative to the flow of air. 
     The compressor section may include a row of variable stator vanes downstream from the inlet guide vanes. During various operating conditions, such as startup and shut down of the gas turbine, the inlet guide vanes and the variable stator vanes may be actuated between an open position and a closed position so as to increase or decrease a flow rate of the working fluid entering the compressor section of the gas turbine. 
     These components represent a compromise between different engine regimes. This compromise reduces the efficiency under certain operating conditions. 
     What is needed is an adaptive morphing engine geometry without the drawbacks presented above. 
     SUMMARY 
     In accordance with the present disclosure, there is provided a morphing aerodynamic control surface geometry comprising a control surface having an articulated portion comprising a flexible skin coupled at an exterior of the articulated portion, the flexible skin comprising opposed interlocking elements sandwiched within a flexible polymer coupled to the interlocking elements; wherein the flexible skin is configured compliant responsive to an articulation of the articulated portion. 
     In another and alternative embodiment, the articulated portion is part of a gas turbine engine component selected from the group consisting of a variable geometry splitter, gas flow path, a static engine component, a variable inlet guide vane and an adaptive flap. 
     In another and alternative embodiment, the interlocking elements comprise at least one upper element and at least one lower element opposite the at least one upper element. 
     In another and alternative embodiment, the at least one upper element comprises an upper element exterior surface and an upper element interior feature opposite the upper element exterior surface; the at least one lower element comprises a lower element exterior surface and a lower element interior feature opposite the lower element exterior surface; the upper element interior feature configured to interlock with the lower element interior feature. 
     In another and alternative embodiment, the upper element interior feature and the lower element interior feature comprises inverted edges along a portion of the upper element and the lower element respectively. 
     In another and alternative embodiment, the at least one upper element comprises an upper element exterior surface and an upper element interior surface having a feature opposite the upper element exterior surface; the at least one lower element comprises a lower element exterior surface and a lower element interior surface with a feature opposite the lower element exterior surface; the upper element interior feature configured to interlock with a lower element interior feature. 
     In another and alternative embodiment, the upper element interior feature comprises a peg extending out of a portion of the upper element interior surface and the lower element interior feature comprises a receiver formed in the lower element interior surface. 
     In another and alternative embodiment, the flexible polymer surrounding the interlocking elements comprises a high temperature polymer volcanized to the interlocking elements. 
     In another and alternative embodiment, the flexible polymer comprises a lower stiffness than the interlocking elements. 
     In another and alternative embodiment, the interlocking elements are configured to interlock with a predetermined limit to slide and rotate relative to each other and maintain contact. 
     In another and alternative embodiment, the control surface is configured to articulate into a curved surface configured to produce an aerodynamic effect on a gas passing over the control surface. 
     In another and alternative embodiment, the inverted edges comprise corners bend into flat hooks facing the interior surface for each of the upper element and the lower element. 
     In another and alternative embodiment, the inverted edges of the upper element and the inverted edges of the lower element interlock at the corners. 
     In another and alternative embodiment, the interlocking elements sandwiched within the flexible polymer are configured in a mosaic pattern. 
     In another and alternative embodiment, the interlocking elements comprise at least one of a metal material and a ceramic composite material. 
     In another and alternative embodiment, the interlocking elements sandwiched within the flexible polymer are configured in a spaced apart pattern. 
     In another and alternative embodiment, the interlocking elements sandwiched within the flexible polymer comprise a smooth exterior surface. 
     In another and alternative embodiment, the interlocking elements are bonded together by the flexible polymer. 
     In another and alternative embodiment, the interlocking elements sandwiched within the flexible polymer comprise polygonal shapes. 
     In another and alternative embodiment, the interlocking elements sandwiched within the flexible polymer are formed in multiple layers. 
     Adaptive structural/aerodynamic elements which are comprised of flexible skins can facilitate shapes which are most efficient for the different operating regimes. These shape-morphing structures can be applied both to airfoils and flow-paths. 
     Other details of the adaptive morphing engine geometry are set forth in the following detailed description and the accompanying drawings wherein like reference numerals depict like elements. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic representation of an adaptive flap for a turbine engine. 
         FIG. 2  is a schematic representation of an exemplary variable geometry splitter for a turbine engine. 
         FIG. 3  is a schematic representation of an exemplary adaptive flap for turbine engine with a morphing aerodynamic control surface geometry. 
         FIG. 4  is a schematic representation of an exemplary flexible skin. 
         FIG. 5  is a schematic representation of an exemplary flexible skin. 
         FIG. 6  is a schematic representation of a portion of an exemplary interlocking elements. 
         FIG. 7  is a cross sectional schematic representation of a portion of exemplary interlocking elements within a flexible polymer. 
         FIG. 8  is a schematic representation of exemplary interlocking elements in multiple views. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIGS. 1-3 , there is illustrated a turbine engine component  10 , such as a variable inlet guide vane, a variable geometry splitter, gas flow path, a static engine component, and an adaptive flap. The turbine engine component  10  has an airfoil portion  12  with a leading edge  14  and a trailing edge  16 . The component  10  includes a control surface  18  covering an articulated portion  20 . The articulated portion  20  is shown proximate the trailing edge  16  but can also be located proximate the leading edge  14  and portions between the leading edge  14  and trailing edge  16 . An axis  22  can be utilized to manipulate the articulated portion  20 . In the exemplary embodiments shown in  FIGS. 1 and 2  the axis  22  is a pivot for a flap  24  to rotate about. 
     The articulated portion  20  includes an exterior  26 . A flexible skin  28  is coupled to the exterior  26  of the articulated portion  20 . The flexible skin  28  is configured to be compliant responsive to an articulation of the articulated portion  20 . 
     Referring also to  FIGS. 4 to 8 , the flexible skin  28  includes opposed interlocking elements  30 . The interlocking elements  30  can be sandwiched between a flexible polymer  32 . Polyurethane based elastomers have an excellent combination of high strength, toughness and low modulus and may be one of the candidates for achieving the “shape-change” functionality. The interlocking elements  30  can be bonded together by the flexible polymer  32 . The interlocking elements  30  sandwiched within the flexible polymer can be configured in a mosaic pattern  60  and can be spaced apart. The interlocking elements  30  comprise at least one of a metal material and a ceramic composite material. 
     The interlocking elements  30  can be formed into polygonal, square, rectangle, triangle shapes and the like. The interlocking elements  30  can be sandwiched with the flexible polymer  32  in multiple layers as seen at  FIG. 2 . The flexible polymer  32  surrounding the interlocking elements  30  can comprise a high temperature polymer volcanized to the interlocking elements  30 . The adhesive joint between the flexible polymer  32  and the interlocking elements  30  can be constructed from stiffer materials like aluminum or other light metals, for example, an aluminum surface can be treated with a phosphoric acid etching process to grow an oxide surface having a rough topography. If the adhesive/elastomer is able to fully wet this surface the bond strength will be increased. 
     In an exemplary embodiment, the flexible polymer  32  comprises a lower stiffness than the interlocking elements  30 , such that when a torque is applied to the axis  22  the articulated portion  20  shifts the flexible skin  28  to place the flexible polymer  32  into a shear load SL, such that the flexible polymer  32  is displaced in the direction of the load. The desired curvilinear shape of the control surface  18  is achieved. The interlocking elements  30  are configured to interlock with a predetermined limit to slide and rotate relative to each other and maintain contact with each other. The control surface  18  is configured to articulate into a curved surface  50  configured to produce an aerodynamic effect  52  on a gas  54  passing over said control surface  18 . 
     In another exemplary embodiment the trailing edge  16  is altered by the nonlinear stiffness of the control surface  18  having the flexible polymer  32  sandwiching the relatively stiff interlocking elements  30  in combination of thicknesses on the interlocking elements  30  and the layers of flexible polymer  32  (see insert of  FIG. 2 ). 
     The interlocking elements  30  comprise at least one upper element  34  and at least one lower element  36  opposite the at least one upper element  34 . The upper element  34  comprises an upper element exterior surface  38  and an upper element interior feature  40  opposite the upper element exterior surface  40 . The lower element  36  comprises a lower element exterior surface  42  and a lower element interior feature  44  opposite the lower element exterior surface  42 . The upper element interior feature  40  is configured to interlock with the lower element interior feature  44 . In an exemplary embodiment, the upper element exterior surface  38  and the lower element exterior surface  42  can comprise a smooth exterior surface. 
     In an exemplary embodiment shown at  FIGS. 5-7 , the upper element interior feature  40  and the lower element interior feature  44  comprise inverted edges  46  along a portion or edge  48  of the upper element  34  and the lower element  36  respectively. In another exemplary embodiment, the inverted edges  46  comprise corners  56  bend into flat hooks  58  facing the interior surface for each of the upper element  34  and the lower element  36 . The inverted edges  46  of the upper element  34  and the inverted edges  46  of the lower element  36  can interlock at the corners  56 . 
     In another exemplary embodiment as seen in  FIG. 8 , the upper element  34  can include the upper element exterior surface  38  and an upper element interior surface  62  having a feature  40  opposite the upper element exterior surface  38 . The lower element  36  can include the lower element exterior surface  42  and a lower element interior surface  64  with a feature  44  opposite the lower element exterior surface  42 . The upper element interior feature  40  can be configured to interlock with the lower element interior feature  44 . In an exemplary embodiment, the upper element interior feature  40  can include a peg  66  extending out of a portion of the upper element interior surface  62 . The lower element interior feature  44  can include a receiver  68  formed in the lower element interior surface  64   
     The morphing aerodynamic control surface geometry provides the advantage of significant aerodynamic performance improvement by morphing static engine components. 
     The morphing aerodynamic control surface geometry provides the advantage of designing an adaptive flap to assume different optimal shapes at high-power, where through-flow is important, and at partial power, where stability concerns dominate. 
     The morphing aerodynamic control surface geometry provides the advantage of shape-morphing structures that can be enablers when applied to the flow-path. 
     The morphing aerodynamic control surface geometry provides the advantage in applications with a splitter of a 3-stream fan, where changes in bypass ratio may result in excessive splitter loading. 
     The morphing aerodynamic control surface geometry provides the advantage in applications with engine components such as the variable inlet guide vane and the flow splitters that have a fixed geometry. 
     The morphing aerodynamic control surface geometry provides the advantage for adaptive structural/aerodynamic elements which can include flexible skins that can facilitate shapes which are most efficient for the different operating regimes. 
     The morphing aerodynamic control surface geometry provides the advantage for shape-morphing structures that can be applied both to airfoils and flow-paths. 
     There has been provided an adaptive morphing engine geometry. While the adaptive morphing engine geometry 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.