US20180274783A1 - Auxetic Structures With Angled Slots In Engineered Patterns For Customized NPR Behavior And Improved Cooling Performance - Google Patents

Auxetic Structures With Angled Slots In Engineered Patterns For Customized NPR Behavior And Improved Cooling Performance Download PDF

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US20180274783A1
US20180274783A1 US15/542,636 US201615542636A US2018274783A1 US 20180274783 A1 US20180274783 A1 US 20180274783A1 US 201615542636 A US201615542636 A US 201615542636A US 2018274783 A1 US2018274783 A1 US 2018274783A1
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elongated apertures
rigid body
apertures
npr
elongated
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Katia Bertoldi
Christopher Booth-Morrison
Mehran Farhangi
Matthew Christopher Innes
Farhad Javid
Megan Schaenzer
Ali Shanian
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Siemens Canada Ltd
Harvard University
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Assigned to PRESIDENT AND FELLOWS OF HARVARD COLLEGE reassignment PRESIDENT AND FELLOWS OF HARVARD COLLEGE ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BERTOLDI, KATIA, FARHAD, JAVID
Assigned to SIEMENS CANADA LIMITED reassignment SIEMENS CANADA LIMITED ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SCHAENZER, Megan, BOOTH-MORRISON, CHRISTOPHER, FARHANGI, Mehran, INNES, MATTHEW CHRISTOPHER, SHANIAN, Ali
Publication of US20180274783A1 publication Critical patent/US20180274783A1/en
Assigned to PRESIDENT AND FELLOWS OF HARVARD COLLEGE reassignment PRESIDENT AND FELLOWS OF HARVARD COLLEGE ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: JAVID, Farhad
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
    • F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
    • F23R3/002—Wall structures
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
    • F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
    • F23R3/02—Continuous combustion chambers using liquid or gaseous fuel characterised by the air-flow or gas-flow configuration
    • F23R3/04—Air inlet arrangements
    • F23R3/06—Arrangement of apertures along the flame tube
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C19/00—Alloys based on nickel or cobalt
    • C22C19/03—Alloys based on nickel or cobalt based on nickel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
    • F23R2900/00—Special features of, or arrangements for continuous combustion chambers; Combustion processes therefor
    • F23R2900/00005—Preventing fatigue failures or reducing mechanical stress in gas turbine components
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
    • F23R2900/00—Special features of, or arrangements for continuous combustion chambers; Combustion processes therefor
    • F23R2900/00014—Reducing thermo-acoustic vibrations by passive means, e.g. by Helmholtz resonators
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
    • F23R2900/00—Special features of, or arrangements for continuous combustion chambers; Combustion processes therefor
    • F23R2900/03041—Effusion cooled combustion chamber walls or domes

Definitions

  • the present disclosure relates generally to porous materials and cellular solids with tailored isotropic and anisotropic Poisson's ratios. More particularly, aspects of this disclosure relate to auxetic structures with engineered patterns that exhibit negative Poisson's Ratio (NPR) behavior, as well as systems, methods and devices using such structures.
  • NPR Poisson's Ratio
  • Poisson's Ratio When materials are compressed along a particular axis, they are most commonly observed to expand in directions transverse to the applied axial load. Conversely, most materials contract along a particular axis when a tensile load is applied along an axis transverse to the axis of contraction.
  • the material property that characterizes this behavior is known as the Poisson's Ratio, which can be defined as the negative of the ratio of transverse/lateral strain to axial/longitudinal strain under axial loading conditions.
  • the majority of materials are characterized by a positive Poisson's Ratio, which is approximately 0.5 for rubber, approximately 0.3 for aluminum, brass and steel, and approximately 0.2 for glass.
  • auxetic Materials with a negative Poisson's Ratio (NPR), on the other hand, will contract (or expand) in the transverse direction when compressed (or stretched) in the axial direction.
  • NPR negative Poisson's Ratio
  • auxetic behavior involves an interplay between the microstructure of the material and its deformation. Examples of this are provided by the discovery that metals with a cubic lattice, natural layered ceramics, ferroelectric polycrystalline ceramics, and zeolites may all exhibit negative Poisson's Ratio behavior.
  • auxetic materials A significant challenge in the fabrication of auxetic materials is that it usually involves embedding structures with intricate geometries within a host matrix. As such, the manufacturing process has been a bottleneck in the practical development towards applications.
  • a structure which forms the basis of many auxetic materials is that of a cellular solid. Research into the deformation of these materials is a relatively mature field with primary emphasis on the role of buckling phenomena, on load carrying capacity, and energy absorption under compressive loading. Very recently, the results of a combined experimental and numerical investigation demonstrated that mechanical instabilities in 2D periodic porous structures can trigger dramatic transformations of the original geometry.
  • uniaxial loading of a square array of circular holes in an elastomeric matrix is found to lead to a pattern of alternating mutually orthogonal ellipses while the array is under load.
  • the geometric reorganization observed at the instability is both reversible and repeatable and it occurs over a narrow range of the applied load.
  • the pattern transformation leads to unidirectional negative Poisson's Ratio behavior for the 2D structure, i.e., it only occurs under compression.
  • U.S. Pat. No. 5,233,828 (“828 patent”) shows an example of an engineered void structure—a combustor liner or “heat shield”—utilized in high temperature applications.
  • Combustor liners are typically used in the combustion section of a gas turbine. Combustor liners can also be used in the exhaust section or in other sections or components of the gas turbine, such as the turbine blades.
  • combustors burn gas at intensely high temperatures, such as around 3,000° F. or higher. To prevent this intense heat from damaging the combustor before it exits to a turbine, the combustor liner is provided in the interior of the combustor to insulate the surrounding engine.
  • cooling feature have conventionally been provided, such as is shown in the '828 patent, in the form of spaced cooling holes disposed in a continuous pattern.
  • U.S. Pat. No. 8,066,482 B2 presents an engineered structural member having elliptically-shaped cooling holes to enhance the cooling of a desired region of a gas turbine while reducing stress levels in and around the cooling holes.
  • European Patent No. EP 0971172 A1 likewise shows another example of a perforated liner used in a combustion zone of a gas turbine. None of the above patent documents, however, provide examples disclosed as exhibiting auxetic behavior or being engineered to provide NPR effects.
  • U.S. Patent Application Pub. No. 2010/0009120 A1 discloses various transformative periodic structures which include elastomeric or elasto-plastic periodic solids that experience transformation in the structural configuration upon application of a critical macroscopic stress or strain. Said transformation alters the geometric pattern, changing the spacing and the shape of the features within the transformative periodic structure. Upon removal of the critical macroscopic stress or strain, these elastomeric periodic solids recover their original form.
  • U.S. Patent Application Pub. No. 2011/0059291 A1 discloses structured porous materials, where the porous structure provides a tailored Poisson's ratio behavior.
  • porous structures consist of a pattern of elliptical or elliptical-like voids in an elastomeric sheet which is tailored, via the mechanics of the deformation of the voids and the mechanics of the deformation of the material, to provide a negative or a zero Poisson's ratio.
  • auxetic structures with repeating patterns of elongated apertures (also referred to herein as “voids” or “slots”) that are engineered to provide a desired negative Poisson's Ratio (NPR) behavior and improved cooling performance.
  • NPR negative Poisson's Ratio
  • aspects of the present disclosure are directed to multi-functional NPR structures with angled air passages in the hot section of a gas turbine. Additional aspects are directed towards gas turbine combustors that are made with walls from a material with engineered angled void features that provide particular thermal, damping and/or acoustic functionalities. Such functionalities include, for example, acoustic attenuation (or noise damping), stress reduction (or load damping), and thermal cooling (or heat damping).
  • an auxetic structure includes an elastically rigid body, such as a metallic sheet or other sufficiently elastic solid material, with opposing top and bottom surfaces.
  • First and second pluralities of elongated apertures extend through the elastically rigid body from the top surface to the bottom surface.
  • the first plurality of elongated apertures extends transversely (e.g., orthogonally) with respect to the second plurality of elongated apertures.
  • the first and/or second pluralities of elongated apertures are obliquely angled with the top and/or bottom surfaces of the elastically rigid body.
  • each slot traverses the thickness of a sheet material at an angle that is oblique (e.g., approximately 40-70 degrees) to the material's plane.
  • the elongated apertures are cooperatively configured to provide a desired or minimum cooling performance while exhibiting stress reduction through negative Poisson's Ratio (NPR) behavior under macroscopic planar loading conditions.
  • NPR negative Poisson's Ratio
  • the elongated apertures are engineered with a predefined porosity, a predetermined pattern, and/or a predetermined aspect ratio to achieve the desired NPR behavior.
  • the auxetic structure may exhibit an effusion cooling effectiveness of approximately 30-50%, a porosity of about 0.3 to about 9%, and a Poisson's Ratio of approximately ⁇ 0.2 to ⁇ 0.9%.
  • an effusion-cooling auxetic sheet structure which includes a metallic sheet with opposing top and bottom surfaces.
  • First and second pluralities of elongated apertures extend through the metallic sheet from the top surface to the bottom surface.
  • the first plurality of elongated apertures has a first set of geometric characteristics and is arranged in a first pattern.
  • the second plurality of elongated apertures has a second set of geometric characteristics and is arranged in a second pattern.
  • the elongated apertures of the first plurality are orthogonally oriented with respect to the elongated apertures of the second plurality.
  • Each of the elongated apertures is obliquely angled with respect to the top surface of the elastically rigid body.
  • the geometric characteristics and pattern of the first plurality of elongated apertures are cooperatively configured with the geometric characteristics and pattern of the second plurality of elongated apertures to provide a desired or minimum cooling performance while exhibiting negative Poisson's Ratio (NPR) behavior under macroscopic planar loading conditions.
  • NPR Poisson's Ratio
  • a method for manufacturing an auxetic structure includes: providing an elastically rigid body with opposing top and bottom surfaces; adding to the elastically rigid body a first plurality of apertures extending through the elastically rigid body from the top surface to the bottom surface, the first plurality of apertures being arranged in rows and columns; and, adding to the elastically rigid body a second plurality of apertures extending through the elastically rigid body from the top surface to the bottom surface, the second plurality of apertures being arranged in rows and columns.
  • Each aperture of the first and/or second pluralities of elongated apertures is obliquely angled with the top surface of the elastically rigid body.
  • the first and second pluralities of apertures are cooperatively configured to provide a desired or minimum cooling performance while exhibiting a negative Poisson's Ratio (NPR) behavior under macroscopic planar loading conditions.
  • NPR negative Poisson's Ratio
  • the elongated apertures are engineered with a predefined porosity, a predetermined pattern, and/or a predetermined aspect ratio to achieve the desired NPR behavior.
  • the auxetic structure may exhibit an effusion cooling effectiveness of approximately 30-50% and a Poisson's Ratio of approximately ⁇ 0.2 to ⁇ 0.9%.
  • the elastically rigid body may take on various forms, such as a metallic sheet or other sufficiently elastic solid material.
  • FIG. 1 is a graph of Nominal Strain vs. Poisson's Ratio illustrating the Poisson's Ratio behavior of representative structures with elongated through holes according to aspects of the present disclosure.
  • FIGS. 2A-2C are illustrations of the representative structures of FIG. 1 corresponding to specific data points from the graph.
  • FIGS. 3A and 3B are side-view and perspective-view illustrations, respectively, of an angled NPR S-slot according to aspects of the present disclosure.
  • FIGS. 4A-4D are perspective-view illustrations of other angled NPR slots in accordance with aspects of the present disclosure.
  • FIGS. 5A and 5B are plan-view illustrations of an angled NPR S-slot and an angled NPR Z-slot, respectively, with variable cap rotation in accordance with aspects of the present disclosure.
  • FIGS. 6A-6D are plan-view illustrations of angled NPR S-slots exhibiting a 0-degree angle, a 45-degree angle, a 55-degree angle, and a 65-degree angle, respectively, in accordance with aspects of the present disclosure.
  • FIGS. 7A-7C are graphical illustrations of the cooling behaviors for non-NPR normal cooling holes, normal NPR cooling slots, and angled NPR cooling slots, respectively, in accordance with aspects of the present disclosure.
  • auxetic structures which include repeating patterns of angled slots that provide negative Poisson's Ratio (NPR) behavior when macroscopically loaded.
  • Poisson's Ratio (or “Poisson coefficient”) can be generally typified as the ratio of transverse contraction strain to longitudinal extension strain in a stretched object.
  • Poisson's Ratio is typically positive for most materials, including many alloys, polymers, polymer foams and cellular solids, which become thinner in cross section when stretched.
  • the auxetic structures disclosed herein exhibit a negative Poisson's Ratio behavior.
  • an auxetic structure when compressed along one axis (e.g., in the Y-direction), coaxial strain results in a moment around the center of each cell because of the way the adjacent apertures are arranged. This, in turn, causes the cells to rotate. Each cell rotates in a direction opposite to that of its immediate neighbors. This rotation results in a reduction in the transverse axis (X-direction) distance between horizontally adjacent cells.
  • X-direction transverse axis
  • the unadulterated material itself may have a positive Poisson's Ratio, but by modifying the structure with the introduction of the angled-slot patterns disclosed herein, the structure behaves as having a negative Poisson's Ratio.
  • FIG. 1 is a graph of Poisson's Ratio (PR) against Nominal Strain illustrating the Poisson's Ratio behavior of three representative void structures shown in FIGS. 2A-2C .
  • the chart of FIG. 1 shows the Poisson's Ratio of each test piece under load.
  • the “instantaneous” PR can be determined and plotted against a parameter (e.g., nominal strain) representing the level of deformation.
  • a parameter e.g., nominal strain
  • the NPR aperture patterns can consist of horizontally and vertically oriented, elongated holes (also referred to as “apertures” or “voids” or “slots”), shown as elliptical through slots.
  • the center of each slot is on the crossing point of two of the lines.
  • Horizontally oriented and vertically oriented slots alternate on the vertical and horizontal lines such that any vertically oriented slot is surrounded by horizontally oriented slots (and vice versa), while the next vertically oriented slots are found on both diagonals.
  • These voids can also act as cooling and/or damping holes and, due to their arrangement, also as stress reduction features.
  • One or more of the slots shown herein can be replaced by elongated NPR protrusions or semispherical NPR dimples.
  • gas turbine combustors that are made with one or more walls from a material with any of the specific auxetic structure configurations disclosed herein.
  • the angled slots are generated in a metal body directly in a stress-free state such that the apertures are equivalent in shape to collapsed void shapes found in rubber under external load in order to get NPR behavior in the metal body without collapsing the metallic structure in manufacturing.
  • Various manufacturing routes can be used to replicate the void patterns in the metallic component. The manufacturing does not necessarily contain buckling as one of the process steps.
  • the auxetic structures disclosed herein are not limited to the combustor wall; rather, these features can be incorporated into other sections of a turbine (e.g., a blade, a vane, etc.).
  • holes used for cooling air flow and damping also act as stress risers.
  • the negative Poisson's Ratio will make the wall material contract in the horizontal direction, and vice versa. This behavior will reduce the stresses at the hotspot significantly. This effect is stronger than just the impact of the reduced stiffness. Stress at hot spot gets reduced, for example, by 50% which, in turn, leads to an increase in stress fatigue life by several orders of magnitude.
  • the stress reduction by the NPR behavior does not increase the air consumption of the combustor wall. The longer life could be used as such or the wall material could be replaced by a cheaper one in order to reduce raw material costs.
  • the superalloy may be a nickel-based superalloy, such as Inconel (e.g. IN100, IN600, IN713), Waspaloy, Rene alloys (e.g. Rene 41, Rene 80, Rene 95, Rene N5), Haynes alloys, Incoloy, MP98T, TMS alloys, and CMSX (e.g. CMSX-4) single crystal alloys.
  • Inconel e.g. IN100, IN600, IN713
  • Waspaloy Rene alloys
  • Rene alloys e.g. Rene 41, Rene 80, Rene 95, Rene N5
  • Haynes alloys e.g. Rene 41, Rene 80, Rene 95, Rene N5
  • Haynes alloys e.g. Rene 41, Rene 80, Rene 95, Rene N5
  • Haynes alloys e.g. Rene 41, Rene 80, Rene 95, Rene N5
  • Haynes alloys e.g. Rene 41
  • an optimal aspect ratio for the elongated apertures may be a predetermined optimal aspect ratio for the elongated apertures to provide a desired NPR behavior.
  • “aspect ratio” of the apertures can be defined to mean the length divided by the width of the apertures, or the length of the major axis divided by the length of the minor axis of the apertures. It may be desirable, in some embodiments, that the aspect ratio of the apertures be approximately 5-40 or, in some embodiments, approximately 20-30.
  • An optimal NPR may comprise, for example, a PR of about ⁇ 0.2 to about ⁇ 0.9 or, for some embodiments, about ⁇ 0.5.
  • aspects of the disclosed concepts can be demonstrated on structural patterns created with a pattern lengthscale at the millimeter, and are equally applicable to structures possessing the same periodic patterns at a smaller lengthscale (e.g., micrometer, submicrometer, and nanometer lengthscales) or larger lengthscales so far as the unit cells fit in the structure.
  • a smaller lengthscale e.g., micrometer, submicrometer, and nanometer lengthscales
  • larger lengthscales so far as the unit cells fit in the structure.
  • FIGS. 3A and 3B illustrate an auxetic structure, designated generally at 300 , which utilizes an alternating pattern of elongated asymmetrical slots.
  • the foregoing slots are elongated in that each has a major axis (e.g., a length) that is larger than and perpendicular to a minor axis (e.g., a width).
  • the auxetic structure 300 comprises an elastically rigid body 310 , which may be in the form of a metallic sheet or other solid material with adequate elasticity to return substantially or completely to its original form once macroscopic loading conditions are sufficiently reduced or eliminated.
  • Elastically rigid body 310 has a first (top) surface 314 in opposing spaced relation to a second (bottom) surface 316 .
  • Fabricated into the elastically rigid body 310 is a first plurality of S-shaped through slots (also referred to herein as “apertures” or “voids” or “slots”), represented herein by slot 312 , which extend through the body 310 from the top surface 314 to the bottom surface 316 .
  • a second plurality of S-shaped through slots/apertures also extends through the elastically rigid body 310 from the top surface 314 to the bottom surface 316 .
  • the pattern of elongated apertures present in the elastically rigid body 310 may be similar in arrangement to what is seen in FIGS. 2B and 2C .
  • S-shaped through slots 312 , 318 are arranged in an array or matrix of rows and columns, with the first plurality of elongated apertures 312 extending transversely with respect to the second plurality of elongated apertures 318 .
  • hidden lines indicating the internal structural configuration of slots 318 have been omitted from FIGS. 3A and 3B for clarity to better show the internal structural configuration of slots 312 .
  • the rows are equally spaced from each other and, likewise, the columns are equally spaced from each other.
  • each row and each column comprises vertically oriented S-shaped through slots 312 interleaved with horizontally oriented S-shaped through slots 318 .
  • each vertically oriented through slot 312 is neighbored on four sides by horizontally oriented through slots 318
  • each horizontally oriented through slot 318 is neighbored on four sides by vertically oriented through slots 312 .
  • the minor axes of the first plurality of S-shaped through slots 312 are parallel to the rows of the array
  • the minor axes of the second plurality of S-shaped through slots 318 are parallel to the columns of the array.
  • the major axes of the through slots 318 which are parallel to the rows of the array, are perpendicular to the major axes of the through slots 312 , which are parallel to the columns of the array. It is also envisioned that other patterns and arrangements for achieving stress reduction through NPR behavior are within the scope and spirit of the present disclosure.
  • the illustrated pattern of elongated, angled slots provides a specific porosity (e.g., a porosity of about 0.3 to about 9.0%) and a desired cooling performance (e.g., an effusion cooling effectiveness of approximately 30-50%) while exhibiting a desired negative Poisson's Ratio behavior (e.g., a PR of about ⁇ 0.2 to about ⁇ 0.9) under macroscopic planar loading conditions (e.g., when tension or compression is applied in the plane of the sheet).
  • a specific porosity e.g., a porosity of about 0.3 to about 9.0%
  • a desired cooling performance e.g., an effusion cooling effectiveness of approximately 30-50%)
  • a desired negative Poisson's Ratio behavior e.g., a PR of about ⁇ 0.2 to about ⁇ 0.9
  • macroscopic planar loading conditions e.g., when tension or compression is applied in the plane of the sheet.
  • a cell may consist of two laterally adjacent vertical slots aligned with two vertically adjacent horizontal slots to form a square-shaped unit. Each cell rotates in a direction opposite to that of its immediate neighboring cells. This rotation increases the X-direction distance between horizontally adjacent cells such that stretching the structure in the Y-direction causes it to stretch in the X-direction.
  • the first plurality of S-shaped through slots 312 have (first) engineered geometric characteristics, including a predefined geometry and a predefined aspect ratio, while the second plurality of S-shaped through slots 318 have (second) engineered geometric characteristics, including a predefined geometry and a predefined aspect ratio, that are cooperatively configured with (third) engineered geometric characteristics of the aperture pattern, including NPR-slot density and cell arrangement, to achieve a desired NPR behavior under macroscopic loading conditions.
  • Each slot of the first and/or second pluralities of elongated S-shaped through slots 312 , 318 can be obliquely angled with respect to the top surface 314 or bottom surface 316 , or both, of the auxetic structure's 300 elastically rigid body 310 .
  • slot 312 is shown in FIG. 3A traversing the entire thickness of the material at an angle that is oblique to the material's horizontal plane.
  • each aperture has an angle ⁇ of approximately 20-80 degrees or, in some embodiments, approximately 40-70 degrees with the top and bottom surfaces 314 , 316 of the auxetic structure's body 310 .
  • Inclination angle ⁇ can be defined as the angle between the injection vector and its projection on the material plane. This inclination angle can be varied in a 360° rotational angle of freedom to achieve numerous desired combinations of auxetic behavior and film cooling performance.
  • Patterned angled NPR-slot features such as those disclosed in FIGS. 3-6 , have been shown to cool significantly better than conventional right-angled (normal) circular holes and cooling slots as the internal surface area of the slots is larger than that of normal circular holes or slots.
  • Angled NPR-slot film can benefit from the Coanda Effect, which causes the coolant jet to better adhere to the wall, rather than lifting off and penetrating the mainstream flow. This helps to decrease the inclination angle, which in turn decreases coolant jet penetration and increases cooling performance of NPR slots. From an aerodynamic perspective, the reduced penetration of the coolant jet of angled NPR slots decreases aerodynamic losses due to film cooling compared with normal coolant slot flow.
  • the inclination angle can be varied to achieve a desired combination of auxetic behavior and film cooling performance.
  • a combustor liner with sheet metal walls in which conventional round effusion holes or normal effusion slots are replaced with a pattern of angled S-shaped NPR slots forming an auxetic structure. Cooling air fed through these angled S-shaped slots removes heat from the structure and produces an even distribution of cooling air over the surface.
  • These angled slots which have an increased internal surface area, enhance film cooling performance and improve mechanical response.
  • angled NPR slots are capable of sustaining higher flame temperatures, and help impart to the sheet a much longer life compared to conventional sheet metal walls with normal effusion holes.
  • FIGS. 4A-4D are perspective-view illustrations of other auxetic structures, designated generally at 400 A, 400 B, 400 C and 400 D, respectively, with angled NPR slots in accordance with aspects of the present disclosure.
  • the auxetic structures 400 A- 400 D may include any of the features, options, and alternatives described herein with respect to the other auxetic structures.
  • any of the auxetic structures disclosed herein can share features, options and alternatives with the other disclosed embodiments.
  • Auxetic structures 400 A- 400 D each comprises an elastically rigid body 410 A, 410 B, 410 C and 410 D, respectively, fabricated with a plurality of elongated and angled apertures 412 A, 412 B, 412 C and 412 D, respectively, arranged in a pattern to provide a desired cooling performance while exhibiting a predetermined NPR behavior under macroscopic planar loading conditions.
  • elongated apertures 412 A have an S-shaped plan-view profile
  • the elongated apertures 412 B in FIG. 4B have an I-shaped plan-view profile, which includes a pair of spaced semicircular slots connected by an elongated linear slot.
  • any of the foregoing angled NPR slots can be manufactured by laser cutting, for example, by laying out a linear pattern of NPR slots along the inclination angle to the surface.
  • the profile of the angled NPR slots that appears on the outer (top) surface can be designed as a projection of a standard shape—e.g., a standard “S” 414 A, a standard “I” 414 B with rounded arms, a standard barbell 414 C with circular ends, and a standard ellipse 414 D.
  • a standard shape e.g., a standard “S” 414 A, a standard “I” 414 B with rounded arms, a standard barbell 414 C with circular ends, and a standard ellipse 414 D.
  • the profile of the angled NPR slots that appears on the outer (top) surface can be highly distorted from the original image depending, for example, on the desired angle and/or orientation of the slot.
  • FIGS. 6A-6D illustrate slot distortion on an outer surface of a tubular auxetic structure: FIG.
  • FIG. 6A illustrating normal NPR S-slots exhibiting a 0-degree angle
  • FIG. 6B illustrating angled NPR S-slots exhibiting a 45-degree angle
  • FIG. 6C illustrating angled NPR S-slots exhibiting a 55-degree angle
  • FIG. 6D illustrating angled NPR S-slots exhibiting a 65-degree angle.
  • a new NPR slot shape for instance, Z-shaped slots 512 A ( FIG. 5A ) and S-shaped slots ( FIG. 5B ), can be developed by reducing cap length 511 A and 511 B and/or cap height 513 A and 513 B to provide a horizontal projection similar to an existing or “standard” S-shape/Z-shape.
  • the size and shape of the caps can be varied to achieve a desired combination of auxetic behavior and film cooling performance.
  • Film cooling performance of angled effusion S-shaped slots or, equivalently, Z-shaped slots can be improved by producing a longer cooling thermal layer above the hot surface.
  • a longer cooling thermal layer can be created by increasing the lateral area of the slots normal to the free mainstream fluid by rotating the S-shaped slot cap in the counter-clockwise direction (or clockwise direction for Z-shaped slot caps).
  • This cap rotation angle 515 A and 515 B can be varied to achieve a desired combination of auxetic behavior and film cooling performance.
  • aspects of this disclosure are also directed to methods of manufacturing and methods of using auxetic structures.
  • a method is presented for manufacturing an auxetic structure, such as the auxetic structures described above with respect to FIGS. 3-6 .
  • the method includes, as an inclusive yet non-exclusive set of acts: providing an elastically rigid body, such as the elastically rigid body 310 of FIGS. 3A and 3B , with opposing top and bottom surfaces; adding to the elastically rigid body a first plurality of apertures, such as the elongated S-shaped slots 312 of FIGS.
  • the first and second pluralities of apertures are arranged in rows and columns. Each aperture of the first and/or second plurality is obliquely angled with the top surface of the elastically rigid body.
  • the first and second pluralities of apertures are cooperatively configured to provide a predefined cooling performance while exhibiting a predetermined negative Poisson's Ratio (NPR) behavior under macroscopic planar loading conditions.
  • NPR negative Poisson's Ratio
  • the elongated apertures are engineered with a predefined porosity, a predetermined pattern, and/or a predetermined aspect ratio to achieve the desired NPR behavior.
  • the auxetic structure may exhibit an effusion cooling effectiveness of approximately 30-50% and a Poisson's Ratio of approximately ⁇ 0.2 to ⁇ 0.9%.
  • the elastically rigid body may take on various forms, such as a metallic sheet or other sufficiently elastic solid material.
  • the method includes at least those steps enumerated above and illustrated in the drawings. It is also within the scope and spirit of the present invention to omit steps, include additional steps, and/or modify the order presented above. It should be further noted that the foregoing method can be representative of a single sequence for designing and fabricating an auxetic structure. However, it is expected that the method will be practiced in a systematic and repetitive manner.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)
US15/542,636 2015-01-09 2016-01-09 Auxetic Structures With Angled Slots In Engineered Patterns For Customized NPR Behavior And Improved Cooling Performance Abandoned US20180274783A1 (en)

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US201562101840P 2015-01-09 2015-01-09
US201562118826P 2015-02-20 2015-02-20
US15/542,636 US20180274783A1 (en) 2015-01-09 2016-01-09 Auxetic Structures With Angled Slots In Engineered Patterns For Customized NPR Behavior And Improved Cooling Performance
PCT/US2016/012769 WO2016112368A1 (en) 2015-01-09 2016-01-09 Auxetic structures with angled slots in engineered patterns for customized npr behavior and improved cooling performance

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JP (1) JP2018508738A (enExample)
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CA (1) CA2973378A1 (enExample)
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JP2018504557A (ja) * 2015-01-09 2018-02-15 プレジデント アンド フェローズ オブ ハーバード カレッジ Ｎｐｒ挙動と改善された応力性能を提供するための、工学設計によるパターンで変形した投影スロットを有するオーゼティック構造体
US11536174B2 (en) 2017-07-20 2022-12-27 President And Fellows Of Harvard College Acoustic damper for gas turbine combustors with orthogonal slots
CN111299402A (zh) * 2019-11-29 2020-06-19 湖南飞沃新能源科技股份有限公司 一种热墩生产线
CN115621608A (zh) * 2022-09-21 2023-01-17 南京航空航天大学 一种基于开闭孔负泊松比胞元混合排列的防护与散热结构

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US6427446B1 (en) * 2000-09-19 2002-08-06 Power Systems Mfg., Llc Low NOx emission combustion liner with circumferentially angled film cooling holes
US7546737B2 (en) * 2006-01-24 2009-06-16 Honeywell International Inc. Segmented effusion cooled gas turbine engine combustor
US20110059291A1 (en) * 2009-09-07 2011-03-10 Boyce Christopher M Structured materials with tailored isotropic and anisotropic poisson's ratios including negative and zero poisson's ratios
GB201105790D0 (en) * 2011-04-06 2011-05-18 Rolls Royce Plc A cooled double walled article
FR2979416B1 (fr) * 2011-08-26 2013-09-20 Turbomeca Paroi de chambre de combustion
WO2014151045A1 (en) * 2013-03-15 2014-09-25 President And Fellows Of Harvard College Low porosity auxetic sheet
US9709274B2 (en) * 2013-03-15 2017-07-18 Rolls-Royce Plc Auxetic structure with stress-relief features
US9353783B2 (en) * 2013-03-15 2016-05-31 Rolls-Royce Canada, Ltd. Auxetic locking pin

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EP3242758A4 (en) 2018-07-18
RU2017126597A3 (enExample) 2019-06-04
CN108367329A (zh) 2018-08-03
JP2018508738A (ja) 2018-03-29
EP3242758B1 (en) 2019-09-11
RU2017126597A (ru) 2019-02-11
EP3242758A1 (en) 2017-11-15
CN108367329B (zh) 2021-04-09
CA2973378A1 (en) 2016-07-14

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