阅读说明：本技术 燃气轮机及燃气轮机用火焰筒 (Gas turbine and combustor liner for gas turbine ) 是由 李珊珊 静大亮 张哲铭 于 2021-08-18 设计创作，主要内容包括：本发明公开了一种燃气轮机用火焰筒和燃气轮机,包括筒体和肋片,所述筒体内设有供热燃气流通的燃气通道,所述筒体具有第一端和第二端,所述筒体的第一端适于所述热燃气流入所述燃气通道,所述筒体的第二端适于所述热燃气流出所述燃气通道；所述肋片设在所述筒体的外周壁上,所述肋片沿着所述筒体的周向延伸闭合或所述肋片沿着从所述筒体的第一端至所述筒体的第二端的方向倾斜、螺旋延伸,所述肋片上设有引流槽,所述引流槽沿着所述肋片的延伸方向延伸并环绕在所述筒体的外周侧。本发明的燃气轮机用火焰筒的坑却效率高、冷却效果好,延长了燃气轮机的使用寿命。(The invention discloses a flame tube for a gas turbine and the gas turbine, which comprise a tube body and fins, wherein a gas channel for hot gas to flow through is arranged in the tube body, the tube body is provided with a first end and a second end, the first end of the tube body is suitable for the hot gas to flow into the gas channel, and the second end of the tube body is suitable for the hot gas to flow out of the gas channel; the fin is established on the periphery wall of barrel, the fin is along the circumference of barrel extends closed or the fin is along following the first end of barrel extremely the direction slope of the second end of barrel, spiral extension, be equipped with the drainage groove on the fin, the drainage groove along the extending direction of fin extends and encircles the periphery side of barrel. The flame tube for the gas turbine has high pit cooling efficiency and good cooling effect, and prolongs the service life of the gas turbine.)

1. A combustor basket for a gas turbine, comprising:

a cylinder having a gas passage for hot gas to flow through, the cylinder having a first end and a second end, the first end of the cylinder being adapted for the hot gas to flow into the gas passage and the second end of the cylinder being adapted for the hot gas to flow out of the gas passage;

the fin is arranged on the peripheral wall of the barrel, the fin is closed along the circumferential extension of the barrel or extends along the direction from the first end of the barrel to the second end of the barrel in an inclined and spiral mode, a drainage groove is formed in the fin, and the drainage groove extends along the extending direction of the fin and surrounds the peripheral side of the barrel.

2. The combustor basket for a gas turbine as in claim 1, wherein said fins have a leeward side and a windward side arranged in sequence in a direction from said first end of said barrel to said second end of said barrel, said flow-guiding grooves being provided on said windward side of said fins.

3. The combustor basket for a gas turbine according to claim 2, wherein the rib includes a first rib section and a second rib section, an inner side of the first rib section is connected to the outer circumferential wall of the cylinder, the second rib section is connected to an outer side of the first rib section and extends toward the second end of the cylinder, and the flow guide groove is formed in an area surrounded by the first rib section, the second rib section and the outer circumferential wall of the cylinder.

4. The combustor basket for a gas turbine as set forth in claim 3, wherein said first fin section is closed along a circumferential extension of said barrel, said second fin section is closed along a circumferential extension of said barrel, and said flow guide groove is an annular groove and is circumferentially closed along an outer circumferential side of said barrel.

5. The combustor basket for a gas turbine according to claim 3, wherein the first fin section has a first side and a second side that are oppositely disposed in a direction from the first end of the barrel to the second end of the barrel, the first side is located on a leeward side of the fin, the second side is located on a windward side of the fin, the first side and the second side are both arc-shaped surfaces, at least a portion of the first side extends in a curved manner toward the first end of the barrel and is smoothly connected to the outer peripheral wall of the barrel, and at least a portion of the second side extends in a curved manner toward the second end of the barrel and is smoothly connected to the outer peripheral wall of the barrel.

6. The combustor basket for a gas turbine as in claim 3, wherein a junction of said first rib section and said second rib section is radiused.

7. The combustor basket for a gas turbine as claimed in claim 1, wherein said cylinder includes a first section and a second section, an air flow velocity of said first section outer circumferential side is smaller than an air flow velocity of said second section outer circumferential side, and a height dimension H1 of said first section outer circumferential side rib is larger than a height dimension H2 of said second section outer circumferential side rib.

8. The combustor basket for a gas turbine as in claim 7, wherein a height dimension H1 of said first outer peripheral side rib is 0.8 mm to 1.2 mm.

9. The combustor basket for a gas turbine as in any one of claims 1 to 8, wherein a height profile of at least a portion of the fins in a direction of extension of the fins or a cross-section of at least a portion of the fins is one or a combination of serrated, merlony, and laced.

10. A gas turbine engine, characterized by comprising a combustor basket according to any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of cooling of a flame tube for a gas turbine, in particular to a flame tube for a gas turbine and the gas turbine.

Background

The combustion chamber of the gas turbine is internally provided with a fuel injection device, a flame tube, a transition section and the like, the fuel injection device is used for injecting fuel to the flame tube and mixing and burning the fuel and gas in the combustion chamber, and hot combustion gas generated by burning is conveyed to the turbine through the flame tube and the transition section. Since the liner needs to operate at high temperature conditions, the liner needs to be cooled efficiently to meet expected service life requirements. However, in the related art, the cooling effect of the flame tube has a large difference in different working states of different gas turbines, especially for a low-load point, the flow speed in the outer annular cavity of the flame tube is low, and a strong high-temperature region still exists in a part of regions, so that the cooling effect is reduced, and the service life of the gas turbine is influenced.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art.

Therefore, the embodiment of the invention provides the flame tube for the gas turbine, which has high pit cooling efficiency and good cooling effect and prolongs the service life of the gas turbine.

The embodiment of the invention also provides a gas turbine using the flame tube for the gas turbine.

A combustor basket for a gas turbine according to an embodiment of the present invention includes: a cylinder having a gas passage for hot gas to flow through, the cylinder having a first end and a second end, the first end of the cylinder being adapted for the hot gas to flow into the gas passage and the second end of the cylinder being adapted for the hot gas to flow out of the gas passage; the fin is arranged on the peripheral wall of the barrel, the fin is closed along the circumferential extension of the barrel or extends along the direction from the first end of the barrel to the second end of the barrel in an inclined and spiral mode, a drainage groove is formed in the fin, and the drainage groove extends along the extending direction of the fin and surrounds the peripheral side of the barrel.

According to the gas turbine provided by the embodiment of the invention, the pit of the flame tube for the gas turbine is high in efficiency and good in cooling effect, and the service life of the gas turbine is prolonged.

In some embodiments, the fins have a leeward side and a windward side arranged in sequence in a direction from the first end of the barrel to the second end of the barrel, and the drainage grooves are provided on the windward side of the fins.

In some embodiments, the rib comprises a first rib section and a second rib section, the inner side of the first rib section is connected with the outer circumferential wall of the cylinder, the second rib section is connected with the outer side of the first rib section and extends towards the second end of the cylinder, and the drainage groove is formed in the area enclosed by the first rib section, the second rib section and the outer circumferential wall of the cylinder.

In some embodiments, the first rib section is closed along the circumferential extension of the cylinder, the second rib section is closed along the circumferential extension of the cylinder, and the drainage groove is an annular groove and is closed around along the outer circumferential side of the cylinder.

In some embodiments, the first fin section has a first side surface and a second side surface which are oppositely arranged along the direction from the first end of the cylinder body to the second end of the cylinder body, the first side surface is positioned on the leeward side of the fin, the second side surface is positioned on the windward side of the fin, the first side surface and the second side surface are both arc-shaped surfaces, at least part of the first side surface extends towards the first end of the cylinder body in a bending way and is smoothly connected with the peripheral wall of the cylinder body, and at least part of the second side surface extends towards the second end of the cylinder body in a bending way and is smoothly connected with the peripheral wall of the cylinder body.

In some embodiments, a junction of the first rib segment and the second rib segment is radiused.

In some embodiments, the cylinder includes a first section and a second section, the airflow velocity on the peripheral side of the first section is less than the airflow velocity on the peripheral side of the second section, and the height dimension H1 of the peripheral side of the first section is greater than the height dimension H2 of the peripheral side of the second section.

In some embodiments, the first peripheral side rib has a height dimension H1 of 0.8 mm to 1.2 mm.

In some embodiments, a height profile of at least a portion of the fins along an extending direction of the fins or a cross-section of at least a portion of the fins is one or a combination of saw-tooth shape, city wall shape, and lace shape.

The gas turbine according to the embodiment of the present invention includes a combustor basket, which is the combustor basket for the gas turbine according to any one of the above embodiments.

Drawings

FIG. 1 is a perspective view of the overall structure of a flame tube according to an embodiment of the invention.

FIG. 2 is a schematic side view of the liner of FIG. 1.

Fig. 3 is a schematic cross-sectional view at a-a in fig. 2.

Fig. 4 is a partially enlarged schematic view at a in fig. 3.

Fig. 5 is a partially enlarged schematic view at a in fig. 3 according to another embodiment of the present invention.

FIG. 6 is a schematic view of a serrated rib in accordance with an embodiment of the present invention.

FIG. 7 is a schematic illustration of a city wall fin according to an embodiment of the present invention.

FIG. 8 is a schematic view of a lace-like rib according to an embodiment of the present invention.

FIG. 9 is a schematic diagram of a combination rib according to an embodiment of the present invention.

Reference numerals:

a cylinder body 1; a gas channel 11;

a rib 2; a first side 21; a second side 22; rib outer peripheral surfaces 23; a flow guide groove 24; a drainage groove 25; a first rib section 26; a second rib section 27.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

As shown in fig. 1 to 5, a combustor basket for a gas turbine according to an embodiment of the present invention includes a cylindrical body 1 and fins 2.

A gas channel 11 for hot gas circulation is arranged in the cylinder body 1, the cylinder body 1 is provided with a first end and a second end, the first end of the cylinder body 1 is suitable for hot gas to flow into the gas channel 11, and the second end of the cylinder body 1 is suitable for hot gas to flow out of the gas channel 11.

Specifically, as shown in fig. 1 and fig. 2, a gas channel 11 is provided in the cylinder 1, the first end of the cylinder 1 is the front end of the cylinder 1, and the second end of the cylinder 1 is the rear end of the cylinder 1, during use, hot gas can flow into the gas channel 11 from the front end of the cylinder 1, and then flow out from the rear end of the cylinder 1.

The fin 2 is arranged on the peripheral wall of the cylinder 1, the fin 2 extends and closes along the circumferential direction of the cylinder 1 or the fin 2 extends obliquely and spirally along the direction from the first end of the cylinder 1 to the second end of the cylinder 1, the fin 2 is provided with a drainage groove 25, and the drainage groove 25 extends along the extending direction of the fin 2 and surrounds the peripheral side of the cylinder 1.

Specifically, as shown in fig. 1 and 2, the fins 2 may be annular, the fins 2 are provided on the outer peripheral side of the cylinder 1 and are closed to form a circle along the circumferential direction of the cylinder 1, and the fins 2 may be plural, and the plural fins 2 are arranged at intervals along the axial direction of the cylinder 1. In this case, the drainage groove 25 is a circular groove, the drainage groove 25 is closed along the extension of the fin 2 and surrounds the outer circumference of the cylinder 1, for example, the cross section of the fin 2 may be rectangular, the fin 2 has a front side, a rear side and a fin outer circumferential surface 23, and the drainage groove 25 may be provided on the rear side of the fin 2.

It will be understood that in other embodiments, the fins 2 on the cylinder 1 may be spirally wound on the outer periphery of the cylinder 1, for example, the fins 2 on the cylinder 1 may be arranged at intervals along the circumference of the cylinder 1, and each fin 2 is spirally wound in a direction from the first end of the cylinder 1 to the second end of the cylinder 1. In this case, the drainage groove 25 is an elongated groove, the drainage groove 25 extends along the fin 2 and is located on the outer peripheral side of the cylinder 1, for example, the cross section of the fin 2 may be rectangular, the fin 2 has a front side, a rear side, and a fin outer peripheral surface 23, and the drainage groove 25 may be provided on the rear side of the fin 2.

According to the combustor basket for a gas turbine of the embodiment of the present invention, the separation vortex can be formed downstream of the fin outer circumferential surface 23, and the separation vortex can destroy the main flow structure of the outer side surface of the combustor basket, so that the heat exchange on the outer circumferential side of the combustor basket can be enhanced. In addition, as shown in fig. 4, a diversion groove 24 is formed between two adjacent fins 2, turbulent flow is formed in the diversion groove 24, because two adjacent diversion grooves 24 are separated by the fins 2, the turbulent flow in the diversion groove 24 is relatively independent and does not interfere with each other, when a local main flow changes, the turbulent flow structure in the adjacent diversion groove 24 is not influenced, and therefore, the cooling effect is more stable.

In addition, as the flow guide grooves 25 are additionally arranged on the fins 2, on one hand, the flow guide grooves 25 have the function of increasing the heat exchange area of the fins 2 and the main flow, so that the cooling effect and the cooling efficiency of the flame tube can be further enhanced; on the other hand, when the airflow flows through the diversion trench, turbulence can be formed in the diversion trench, so that the flow of the airflow can be delayed, the heat exchange between the fins 2 and the main flow is more sufficient, and the cooling effect and the cooling efficiency of the flame tube are further enhanced. Secondly, because the guiding gutter extends along fin 2, can form cooling air current in the guiding gutter, and the cooling air current in the guiding gutter is difficult to receive the influence of mainstream air current, has played the effect of protection cooling vortex structure to improve the cooling effect, strengthened refrigerated stability.

In some embodiments, the fins 2 have a leeward side and a windward side arranged in sequence in a direction from the first end of the barrel 1 to the second end of the barrel 1, and the drainage grooves 25 are provided on the windward side of the fins 2.

Specifically, as shown in fig. 4, the airflow on the outer circumferential side of the flame tube flows in the direction from back to front, the rear side of the rib 2 is the windward side of the rib 2, the front side of the rib 2 is the leeward side of the rib 2, and the drainage groove 25 is provided on the rear side of the rib 2 and extends along the rear side of the rib 2. From this, the air current in the drainage groove 25 is located the windward side, has avoided the cooling air current of drainage groove 25 to receive the condition that the mainstream influences, has improved the cooling effect, has strengthened refrigerated stability.

In some embodiments, the rib 2 comprises a first rib section 26 and a second rib section 27, wherein the inner side of the first rib section 26 is connected with the outer circumferential wall of the barrel 1, the second rib section 27 is connected with the outer side of the first rib section 26 and extends towards the second end of the barrel 1, and the drainage groove 25 is formed in the area enclosed by the first rib section 26, the second rib section 27 and the outer circumferential wall of the barrel 1.

Specifically, as shown in fig. 4, in the radial direction of the cylinder 1, the rib 2 includes a first rib section 26 and a second rib section 27, wherein the first rib section 26 extends substantially in the radial direction of the cylinder 1, i.e., an inner end of the first rib section 26 is connected to the cylinder 1, the second rib section 27 is connected to an outer end of the first rib section 26 and is located at a rear side of the first rib section 26, and the second rib section 27 is substantially parallel to the axial direction of the cylinder 1. Therefore, the first rib segments 26 and the second rib segments 27 are bent to facilitate the processing and forming of the drainage grooves 25, and the first rib segments 26 and the second rib segments 27 can be processed and formed in a stamping mode during processing, so that the situation that the fins 2 need to be subjected to undercutting is avoided, and the processing cost and the material cost are reduced.

In some embodiments, the first rib section 26 is closed along the circumferential extension of the cylinder 1, the second rib section 27 is closed along the circumferential extension of the cylinder 1, and the drainage groove 25 is an annular groove and is closed around along the outer circumferential side of the cylinder 1.

Specifically, as shown in fig. 1 and 4, there are a plurality of first rib segments 26, each of the plurality of first rib segments 26 is annular and surrounds the outer circumferential side of the cylinder 1, and the plurality of first rib segments 26 are arranged at equal intervals along the extending direction of the cylinder 1. The rear side of the outer end of each first rib section 26 is connected with a second rib section 27, the second rib sections 27 extend along the front-rear direction, the second rib sections 27, the first rib sections 26 and the outer peripheral wall of the barrel body 1 are surrounded to form a ring-shaped groove, the ring-shaped groove surrounds the outer peripheral side of the barrel body 1, and the ring-shaped groove forms the drainage groove 25.

In some embodiments, the first rib segment 26 has a first side 21 and a second side 22 oppositely arranged along the direction from the first end of the cylinder 1 to the second end of the cylinder 1, the first side 21 is located at the leeward side of the fin 2, the second side 22 is located at the windward side of the fin 2, both the first side 21 and the second side 22 are arc-shaped surfaces, at least a part of the first side 21 extends in a bending way towards the first end of the cylinder 1 and is smoothly connected with the peripheral wall of the cylinder 1, and at least a part of the second side 22 extends in a bending way towards the second end of the cylinder 1 and is smoothly connected with the peripheral wall of the cylinder 1.

Specifically, as shown in fig. 4, the first side surface 21 of the first rib section 26 is a front side surface of the first rib section 26, and the first side surface 21 and the outer circumferential wall of the cylinder 1 are in rounded transition, and the second side surface 22 and the outer circumferential wall of the cylinder 1 are in rounded transition. From this, on the one hand can guarantee the joint strength of fin 2 and barrel 1, on the other hand has still avoided the condition that produces the dead angle in the water conservancy diversion recess 24 for the torrent in the water conservancy diversion recess 24 can smoothly flow, is favorable to improving the heat dissipation.

In some embodiments, the junction of the first rib segment 26 and the second rib segment 27 is radiused. Specifically, as shown in fig. 4 and 5, the first rib section 26 has a first side face 21 and a second side face 22, the second rib section 27 has a rib outer peripheral face 23 and a rib 2 inner peripheral face which are arranged oppositely, the rib outer peripheral face 23 and the first side face 21 are smoothly connected by a curved face, and the rib 2 inner peripheral face and the second side face 22 are smoothly connected by a curved face. Therefore, on one hand, the first rib section 26 and the second rib section 27 have high connection strength, on the other hand, the condition that dead angles are generated at the connection position is avoided, and the smoothness of air flow is guaranteed.

In some embodiments, the cylinder 1 includes a first section and a second section, the airflow velocity on the outer periphery of the first section is less than the airflow velocity on the outer periphery of the second section, and the height dimension H1 of the fins 2 on the outer periphery of the first section is greater than the height dimension H2 of the fins 2 on the outer periphery of the second section.

Specifically, in the front-to-rear direction, the cylinder 1 may include a first section (not shown) and a second section (not shown), both of which are axial sections of the cylinder 1, and during the use of the flame tube, the gas flow rate at the outer periphery of the first section is smaller than that at the outer periphery of the second section, it should be noted that the positions of the first section and the second section may be confirmed empirically and/or by means of monitoring by sensors, for example, in the design stage, the flame tube may be first installed in the combustion chamber, then a plurality of sensors may be disposed at the outer periphery of the flame tube, the sensors may sense the gas flow rate, then the gas turbine operation conditions are simulated, and the position of the first section on the cylinder 1 is confirmed by monitoring the gas flow rate at each section of the cylinder 1, and the rest positions on the cylinder 1 except for the first section may be regarded as the second section.

As shown in fig. 5, the height dimension H1 of the element 2 corresponding to the first segment is greater than the height dimension H2 of the element 2 corresponding to the second segment. The larger the height dimension of the fins 2, the more remarkable the turbulent flow effect of the fins 2, and the better the cooling effect and cooling efficiency at that point, whereby the cooling performance under the condition of the load (low flow rate) on the outer peripheral side of the cylinder 11 can be improved by increasing the height dimension H1 of the first-stage outer peripheral-side fins 2.

In some embodiments, the height of the fins 2 on the outer periphery of the first section varies along the extension of the fins 2.

Specifically, the height dimension of the first-stage outer circumferential-side fins 2 may be gradually increased, gradually decreased, or first increased and then decreased in the front-to-rear direction. Because the height dimension of the fins 2 gradually changes along with the extension direction of the fins 2, the disturbance of the main flow structure can be further increased due to the change of the height dimension, and a disturbed flow and a secondary flow vortex are formed, so that the cooling efficiency of the flame tube is further improved. Due to the enhanced cooling effect and cooling efficiency of the combustor basket, the service life of the combustor basket is increased and the operation is more stable, thereby facilitating the extension of the service life of the gas turbine.

In some embodiments, the height dimension H1 of the first peripheral rib section 2 is 0.8 mm to 1.2 mm.

Specifically, as shown in fig. 5, the height dimension H1 of the fins 2 on the outer peripheral side of the first stage may be any value between 0.8 mm and 1.2 mm, for example, the height dimension H1 may be 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, or the like. The height H1 is designed in the above-mentioned range to achieve a turbulent flow effect on the one hand and to avoid the situation that the fins 2 are high enough to disturb the main flow on the other hand.

In some embodiments, the height profile of at least a part of the fins 2 in the extension direction of the fins 2 or the cross-section of at least a part of the fins 2 is one or a combination of saw-tooth, city wall, lace.

Specifically, as shown in fig. 5, a cross section of the rib 2 is shown, a height section of the rib 2 in the extending direction is a section perpendicular to the cross section of the rib 2, and the section of the rib 2 may be one of a saw-tooth shape, a city wall shape and a lace shape, or a combination of two or more of the saw-tooth shape, the city wall shape and the lace shape, as shown in fig. 6 to 9. Similarly, the cross section of the rib 2 may be one of a saw-tooth shape, a city wall shape and a lace shape, or a combination of two or more of a saw-tooth shape, a city wall shape and a lace shape, as shown in fig. 6 to 9.

Therefore, the turbulent flow of the main flow structure can be further enhanced, and the cooling effect and the cooling efficiency are further enhanced.

A gas turbine according to an embodiment of the present invention is described below.

According to the embodiment of the invention, the gas turbine comprises the flame tube, and the flame tube can be the flame tube described in the embodiment. Specifically, the gas turbine comprises a combustion chamber, a flame tube, a fuel injection device and a transition section, wherein the flame tube is arranged in the combustion chamber, the fuel injection device is arranged at the front end of the flame tube, the transition section is connected to the rear end of the flame tube, the transition section is a transition pipe, and the transition section is connected between the flame tube and the turbine. Part of air compressed by the air compressor flows from back to front along the peripheral side of the flame tube, exchanges heat with the tube body and the fins on the peripheral side of the flame tube, and then cools the flame tube, returns back to flow into the flame tube through the front end device of the flame tube, and is mixed with fuel sprayed by the fuel spraying device for combustion.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless explicitly specifically defined otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; may be mechanically coupled, may be electrically coupled or may be in communication with each other; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.