Patent Publication Number: US-2019170015-A1

Title: Management of heat conduction using phononic regions having metallic glass nanostructures

Description:
BACKGROUND 
     Disclosed embodiments are primarily related to gas turbine engines and, more particularly to phonon management in gas turbine engines. However, the disclosed embodiments may also be used in other heat impacted devices, structures or environments. 
     2. DESCRIPTION OF THE RELATED ART 
     Gas turbines engines comprise a casing or cylinder for housing a compressor section, a combustion section, and a turbine section. A supply of air is compressed in the compressor section and directed into the combustion section. The compressed air enters the combustion inlet and is mixed with fuel. The air/fuel mixture is then combusted to produce high temperature and high pressure gas. This working gas then travels past the combustor transition and into the turbine section of the turbine. 
     Generally, the turbine section comprises rows of vanes which direct the working gas to the airfoil portions of the turbine blades. The working gas travels through the turbine section, causing the turbine blades to rotate, thereby turning a rotor in power generation applications or directing the working gas through a nozzle in propulsion applications. A high efficiency of a combustion turbine is achieved by heating the gas flowing through the combustion section to as high a temperature as is practical. The hot gas, however, may degrade the various metal turbine components, such as the combustor, transition ducts, vanes, ring segments and turbine blades that it passes when flowing through the turbine. 
     For this reason, strategies have been developed to protect turbine components from extreme temperatures such as the development and selection of high temperature materials adapted to withstand these extreme temperatures and cooling strategies to keep the components adequately cooled during operation. 
     Some of the components used in the gas turbine engines are metallic and therefore have very high heat conductivity. Insulating materials, such as ceramic may also be used for heat management, but their properties sometimes prevent them from soley being used as components. Therefore, providing heat management to improve the efficiency and life span of components and the gas turbine engines is further needed. Of course, the heat management techniques and inventions described herein are not limited to use in context of gas turbine engines, but are also applicable to other heat impacted devices, structures or environments. 
     SUMMARY 
     Briefly described, aspects of the present disclosure relate to materials and structures for managing heat conduction in components. For example gas turbine engines, kilns, smelting operations and high temperature auxiliary equipment. 
     An aspect of the disclosure may be a gas turbine engine having a gas turbine engine component with a first material, wherein phononic transmittal through the first material forms a first phononic wave; and a phononic region located within the gas turbine engine component made of metallic glass nanostructures, wherein phononic transmittal to the phononic region modifies behavior of the phonons of the first phononic wave thereby managing heat conduction. 
     Another aspect of the present disclosure may be a method for controlling heat conduction in a gas turbine engine. The method comprises forming a phononic region in a gas turbine engine component, wherein the gas turbine engine component has a first material and the phononic region is made of metallic glass nanostructures; and modifying behavior of phonons transmitted through the first material when the phonons are transmitted to the phononic region thereby managing heat conduction. 
     Still another aspect of the present disclosure may be a gas turbine engine having a gas turbine engine component having a first material, wherein phononic transmittal through the first material forms a first phononic wave; and a nanomesh formed of phononic regions located within the gas turbine engine component, wherein the phononic regions are made of metallic glass nanostructures, wherein phononic transmittal to the phononic region modifies behavior of the phonons of the first phononic wave thereby managing heat conduction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of phonons interacting with a phononic region where a wave property is modified. 
         FIG. 2  is a diagram of phonons interacting with a phononic region where the mode of propagation is altered. 
         FIG. 3  is a diagram of phonons interacting with a phononic region where the movement direction of the phonon is changed. 
         FIG. 4  is a diagram of phonons interacting with a phononic region where the phonons are scattered. 
         FIG. 5  is diagram of phonons interacting with a phononic region where the phonons are reflected. 
         FIG. 6  is a diagram of phonons interacting with a phononic region where waves are refracted. 
         FIG. 7  is a diagram of phonons interacting with a phononic region where the phonons are dissipated. 
         FIG. 8  is a diagram illustrating boundaries of phononic regions formed of metallic glass nanostructure located in a material of a gas turbine engine component. 
         FIG. 9  is a diagram illustrating boundaries of phononic regions formed of metallic glass nanostructure located in a material of a gas turbine engine component. 
         FIG. 10  shows an example of a nanomesh formed on the material of a gas turbine engine component. 
         FIG. 11  shows an example of an alternative embodiment of a nanomesh formed on the material of a gas turbine engine component. 
         FIG. 12  shows an example of columnar metallic glass nanostructures formed on the material of a gas turbine engine component. 
         FIG. 13  shows a diagram of a nanonmesh formed on the material of a gas turbine engine component. 
     
    
    
     DETAILED DESCRIPTION 
     To facilitate an understanding of embodiments, principles, and features of the present disclosure, they are explained hereinafter with reference to implementation in illustrative embodiments. Embodiments of the present disclosure, however, are not limited to use in the described systems or methods. 
     The items described hereinafter as making up the various embodiments are intended to be illustrative and not restrictive. Many suitable items that would perform the same or a similar function as the items described herein are intended to be embraced within the scope of embodiments of the present disclosure. 
     As disclosed herein, the materials used in the gas turbine engines permit the thermal conductivity of pieces to be modified, such as by being reduced in size, without changing the chemical structure in the majority of the material. Management of heat conduction can be achieved through nanostructure modification to portions of the existing gas turbine engine components. There is no need for a large scale bulk material or chemical changes; however smaller scale modifications consistent with aspects of the instant invention may be made to gas turbine engine components. 
       FIG. 1  shows a diagram illustrating the transmission of phonons  10  into a material  20  that is forming part of a gas turbine engine component  100  that can be used in a gas turbine engine. The gas turbine engine component  100  may be a transition duct, liner, part of the combustor, vanes, blades, rings and other gas turbine structures for which heat management would be advantageous. It should also be understood that in addition to gas turbine engine components  100 , the management of heat conduction disclosed herein can be applied to other devices for which heat management is important, for example, marine based turbines, aerospace turbines, boilers, engine bells, heat management devices, internal combustion engines, kilns, smelting operations and any other item wherein heat conduction is a design consideration. 
     The material  20  discussed herein is a metallic material, however it should be understood that other types of materials may be used, such as ceramic and composite materials, when given due consideration for their material properties consistent with aspects of the instant invention. A phonon  10  is generally and herein understood and defined as a quantum of energy associated with a compressional, longitudinal, or other mechanical or electro-mechanical wave such as sound or a vibration of a crystal lattice. Transmissions of phonons  10  collectively transmit heat. The transmissions of phonons  10  form waves in the material  20  as they propagate through the material  20 . 
     In  FIG. 1 , the phonons  10  are transmitted through the material  20  at a first phononic wave W 1 . Formed in the material  20  is a phononic region  30 . The phononic region  30  is designed to modify the behavior of the phonons  10  as they propagate in the one dimensional (1D), two dimensional (2D) and/or three dimensional (3D) spatial regions in the material  20 . The phononic region  30  may modify the behavior of phonons  10  so that they scatter, change direction, change between propagation modes (e.g. change from compression waves to travelling waves), reflect, refract, filter by frequency, and/or dissipate. The modification of the behavior of the phonons  10  controls the heat conduction in the gas turbine engine component  100 . The phononic region  30  described herein is formed by metallic glass, discussed in detail below, that is formed within the material  20 . Metallic glass is a solid metallic material with a disordered atomic-scale structure. Instead of having a crystalline structure, such as standard metals, metallic glass has a non-crystalline structure. Exemplary metallic glasses may be any amount of metallic substance which has a non-crystalline structure and is not oxidized to become a ceramic. These can be formed by very fast heating and/or cooling of metals. The quick cooling prevents the atoms from arranging into crystalline structures. 
     Still referring to  FIG. 1 , the modification of behavior of the phonons  10  by the phononic region  30  may create a second phononic wave W 2 . For example, the first phononic wave W 1  propagates through the material  20 . As the first phononic wave W 1  propagates through the material  20  the first phononic wave W 1  may have the property of having a first frequency λ 1 . When the first phononic wave W 1  interacts with the phononic region  30  the behavior of the phonons  10  may form a second phononic wave W 2  that has the property of a second frequency λ 2 . As the phonons  10  exit from the phononic region  30  and propagate through the material  20  they may continue to propagate at the first frequency λ 1 . 
     The transition from the first frequency λ 1  to the second frequency λ 2  and then back to the first frequency λ 1 , helps manage the heat conduction in the material  20 . Further, by interspersing the material  20  with a number of phononic regions  30  the fluctuation can disrupt the transmission of phonons  10  so as to manage the propagation of phonons  10  and the heat conduction through the material  20  of the gas turbine engine component  100 . 
       FIG. 2  shows a phononic region  30  that modifies the behavior of the first phononic wave W 1  to a second phononic wave W 2  by changing the property of its mode of propagation. In  FIG. 2  the first phononic wave W 1  is altered from a travelling wave to the second phonic wave W 2  which is a compression wave. However it should be understood that it is contemplated that compression waves could be modified to become travelling waves. By modifying the mode of propagation of the waves the heat conduction through the material  20  may be managed. 
       FIG. 3  shows a phononic region  30  that modifies the behavior of the phonons  10  by altering the direction of propagation. Phonons  10  may be moving in one direction D 1  through material  20  and then change direction to direction D 2  as they enter into phononic region  30 . By modifying the direction of the phonons  10  the heat conduction through the material  20  may be managed. 
       FIG. 4  shows a phononic region  30  that modifies the behavior of the phonons  10  so that the phonons  10  are scattered when they enter the phononic region  30  from the material  20 . By scattering it is meant that each phonon  10  that enters the phononic region  30  in direction D 1  may propagate in a random different direction D 2 , D 3 , etc. By modifying the scattering of the phonons  10  the heat conduction through the material  20  may be managed. 
       FIG. 5  shows a phononic region  30  that modifies the behavior of the phonons  10  by reflecting the phonons  10  back into the material  20 . By modifying the behavior of the phonons  10  so that the phonons  10  are reflected by the phononic region  30  the heat conduction through the material  20  may be managed. 
       FIG. 6  shows a first phononic wave W 1  moving through material  20 . When the first phononic wave W 1  reaches the phononic region  30  the first phononic wave W 1  is modified so that it is refracted and becomes second phononic wave W 2  as it passes through the phononic region  30 . As the second phononic wave W 2  exits the phononic region  30  the phononic wave W 2  may be refracted and become a third phononic wave W 3 . By having the phononic region  30  refract the first phononic wave W 1  the heat conduction through the material  20  may be managed. 
       FIG. 7  shows the phononic region  30  located within the material  20  causing phonons  10  from the first phononic wave W 1  to dissipate as it exits the material  20 . By “dissipate” it is meant that at least some of the phonons  10  cease to travel through the phononic region  30  or cease to exist. By having the phononic region  30  dissipate the phonons  10  the heat conduction through the material  20  may be managed. 
       FIG. 8  shows an example of the phononic region  30  formed by the metallic glass nanostructure  35  within the material  20 . The metallic glass nanostructure  35  may form the entirety of the phononic region  30 . In the embodiment shown in  FIG. 8  the phononic regions  30  are used to form metallic glass boundaries  40 . The material  20  may be metallic in that crystalline structures are formed within the material  20 . The metallic glass nanostructures  35  that form the phononic region  30  and metallic glass boundaries  40  can be created by using focused laser pulses during manufacturing of the gas turbine engine component  100 . Other methods for forming the metallic glass nanostructures  35  may include the introduction of dopants to prevent crystalline formation, along with very fast cooling, and sputter deposition of metals which also includes very rapid cooling. 
     The acoustic impedance of the metallic glass nanostructures  35  can be significantly different from the material  20  that is a crystalline metallic material. The phononic regions  30  of metallic glass nanostructures  35  can be formed in a pattern, such that the phononic regions  30  may form metallic glass boundaries  40  that are used to form grids, stripes, columns, rows and other patterns. The width of the metallic glass boundaries  40  may be between 5-1000 nm. The phononic regions  30  formed of metallic glass nanostructures  35  have different acoustic impedances than that of material  20 . Further, by introducing uniformity of direction in the material  20 , and then using metallic glass  35  to form phononic region  30 , sharp changes in the acoustic impedance experienced by phonons  10  propagating through the phononic regions  30  can be instantiated. These localized acoustic impedance changes will cause the phonons  10  to behave in the manner discussed above with respect to  FIGS. 1-7 . Layers of phononic regions  30  can be used to affect heat conduction in the material  20 . 
       FIG. 9  shows a plurality of the metallic glass boundaries  40  formed by the phononic regions  30  in the material  20 . The metallic glass boundaries  40  may be formed by layers or wires formed by phononic regions  30  made of metallic glass nanostructures  35 . By introducing a plurality of phononic regions  30  to form thin or thick metallic glass boundaries  40  of the phononic regions  30  the wave mechanics of phonons  10  can be altered so as to manage heat conduction in the formed gas turbine engine component  100 . The metallic glass boundaries  40  may be from 5 nm to 1000 nm in width. This correlates with the phononic vibration frequencies of approximately 500 GHz to 100 THZ. Because these phononic regions  30  will have differing phononic impedances, they will modify behavior of the propagating phonons  10  in the material  20 , thereby disrupting and reducing heat conduction. These techniques can also be used to direct heat conduction in desired directions by creating channels of optimal propagation for heat-inducing phonons  10  surrounded by phononic regions  30  modifying the behavior of phonons  10 . 
     In each of the above possible ways of managing the heat conduction shown in  FIGS. 1-7 , phonons  10  interacting with phononic regions  30  on the same scale as their wavelength, can modify behavior of phonons  10  to impede propagation of phonons  10  and thus manage heat conduction. The patterns formed by the phononic regions  30  can be used to obtain the modified behavior of the phonons  10  that is desired. For example, patterns of phononic regions  30  parallel to the propagation direction can channel the phonons  10 . Patterns of phononic regions  30  normal to the phonons  10  can reflect them. Patterns of phononic regions  30  at an angle with respect to the propagation direction can scatter or reflect phonons  10  at an angle, spots of acoustic impedance change can cause scattering. 
     The phononic regions  30  may be used in metals and other crystalline material, as well as ceramics. The technique for modifying behavior of the phonons  10  is likely to manage phonons  10  directly more so than thermal free electrons in metals. However, electron propagation may also be affected by the phononic regions  30 , in two possible ways. One, electrons in metals are constantly exchanging their energies with phonons  10 , so management of the phonons  10  has an effect on electrical propagation. Two, if the electron propagation has any frequency component, it would likely be of similar frequencies as the phonon  10 , due to similar interactions that the electrons will have with crystalline structures. In metals, control of phonons  10  may have significant impacts on heat conduction that is mediated by thermal free electrons. 
       FIG. 10  shows an example of a nanomesh  50  formed on material  20  of a gas turbine engine component  100 . In particular, for example, this nanonmesh  50  may be formed on the surface of a vane. The vane may be a modified vane from an existing gas turbine engine component  100 , or alternatively the vane may have been formed with the nanomesh  50 . Additionally the design of the vane may be modified from an existing vane design or alternatively designed in such a fashion so as to take advantage of the use of the nanomesh  50 . The dark spheres are phononic regions  30  made of metallic glass nanostructures  35  which has a different effect on the impedance of phonons  10  than the material  20  formed on the gas turbine engine component  100 . The phononic regions  30  may have diameters that fall within the range of 5-1000 nm. In the example shown the diameters may be in the range 250 nm-400 nm. By having the nanomesh  50  the phonons  10  propagating through the material  20  impacting the nanomesh  50  can be managed. The nanomesh  50  can modify the behavior of the phonons  10  by disrupting the propagation and cause the phonons  10  to behave in the manner shown in  FIGS. 1-7 . The desired behavior can be caused by arranging the nanonmesh  50  to form patterns in the material  20  so that they can be used to manage heat conduction. 
       FIG. 11  shows an alternative embodiment of a nanomesh  51 . In this embodiment, the nanomesh  51  is formed so that the metallic glass nanostructures  35  surround the material  20 . For example, the nanomesh  51  may be formed on the interior surface of a combustor. The combustor may be a modified component from an existing gas turbine engine component  100 , or alternatively the combustor may have been formed with the nanomesh  51 . Additionally the design of the combustor may be modified from an existing combustor design or alternatively designed in such a fashion so as to take advantage of the use of the nanomesh  51 . In this embodiment the metallic glass nanostructures may have widths of 5-1000 nm and formed in such as manner as to surround particles of the material  20 . 
       FIG. 12  shows the formation of metallic glass boundaries  40  made of the metallic glass nanostructures  35 . In particular, for example, these metallic glass boundaries  40  may be formed on the surface of a transition duct. The combustor may be a modified transition duct from an existing gas turbine engine component  100 , or alternatively the transition duct may have been formed with the metallic glass boundaries  40 . Additionally the design of the transition duct may be modified from an existing transition duct design or alternatively designed in such a fashion so as to take advantage of the use of the metallic glass boundaries  40 . In this embodiment, the metallic glass boundaries  40  are formed so that the metallic glass nanostructures  35  form a series of columns. The metallic glass nanostructures  35  forming the metallic glass boundaries  40  may have widths of 5-1000 nm, and as shown in  FIG. 12  are within the range of 10-30 nm. The lengths of the metallic glass boundaries  40  may be from 10 nm-100 cm, and in some instances may have longer lengths depending on its implementation. The metallic glass boundaries  40  can modify the behavior of the phonons  10  by disrupting the propagation and cause the phonons  10  to behave in the manner shown in  FIGS. 1-7 . The desired behavior can be cause by arranging the metallic glass boundaries  40  to form patterns in the material  20  so that they can be used to manage heat conduction. 
       FIG. 13  is diagram illustrating the layered placement of a nanomesh  50  on the material  20  that forms gas turbine engine component  100 . For example, the gas turbine engine component  100  may be a transition duct. The nanomesh  50  is made of metallic glass nanostructures  35  forming a phononic region  30 . The material  20  of the transition duct is a metal. The thickness of the material  20  may be between 100 um to 10 cm. On the surface of the material  20  the nanomesh  50  is formed. The thickness of the nanomesh  50  may be between 5-1000 nm. The nanomesh  50  may be formed in one of the manners discussed above, for example the nanomesh  50  may be formed by adding focused laser pulses during manufacturing of the gas turbine engine component  100 . On the surface of the nanomesh  50  a thermal barrier  54  may be placed. The thermal barrier  54  may be made of a heat resistant material, such as ceramic. The thickness of the thermal barrier  54  may be between 1 mm to 5 cm. Once formed the layered structure can be used to manage the propagation of the heat from the interior of the combustor. This can help reduce the stresses that heat may generate in the material  20  and can extend the life span of gas turbine engine components  100 . 
     While embodiments of the present disclosure have been disclosed in exemplary forms, it will be apparent to those skilled in the art that many modifications, additions, and deletions can be made therein without departing from the spirit and scope of the invention and its equivalents, as set forth in the following claims.