A combustor includes: a combustor case; a combustor liner which is arranged in the combustor case and into which fuel is injected; and an air guide unit that is hollow and is formed to protrude from an inner surface of the combustor liner to inject air into an inside of the combustor liner, wherein the air guide unit includes: a first portion forming one end of the air guide unit and coupled to the inner surface of the combustor liner; and a second portion forming another end of the air guide unit and disposed in the combustor liner, and a size of the first portion is different from a size of the second portion.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims priority from Korean Patent Application No. 10-2021-0191801, filed on Dec. 29, 2021, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND

Example embodiments of the disclosure relate to an air injector arranged in a combustor liner.

2. Description of the Related Art

In the case of a small turbojet engine, it is easy to reduce manufacturing costs, and a slinger based on a high rotation speed of a shaft and a combustor based on a rotary-type fuel injection device are used to inject fuel.

A combustor of the related art is designed in such a way that it is to be manufactured by perforating a liner made of a roll-bent sheet metal material and welding tube-shaped liner parts together. This method may require perforating and welding each tubular liner, thus, complicating a manufacturing process for a combustor liner. Also, the risk of thermal damage to the liner may increase because a welded portion in the tube is more likely to be directly exposed to a high-temperature flame.

Also, in the case of most turbojet engines based on slinger combustors, a deswirler or the like may be omitted, and thus, the swirl angle of air introduced from a compressor may be large. In most engines, because the rotation component of air introduced into a combustor is about 10 degrees but it is about 15 degrees or more in the case of a slinger combustor, the slinger combustor may be disadvantageous over other combustors in terms of pressure loss and flow structure.

Thus, as air is introduced into a liner of the combustor through a vertical air hole, the rotation component of air introduced into the liner may be canceled, the air introduced into the liner may be again expanded by reacting with fuel that is sprayed while rotating, and a rotation component thereof may be again added through a turbine vane nozzle to match the rotation direction of a turbine blade. In this case, it may be necessary to minimize the pressure loss occurring between the rotation component of air introduced from a compressor and the rotation component in the direction of a turbine vane.

SUMMARY

Various example embodiments provide a combustor in which a combustor liner may be more easily manufactured with high performance and combustion performance may be improved by minimizing a pressure loss of air introduced into the combustor liner.

According to example embodiments, a combustor case; a combustor liner which is arranged in the combustor case and into which fuel is injected; and an air guide unit that is hollow and is formed to protrude from an inner surface of the combustor liner to inject air into an inside of the combustor liner, wherein the air guide unit includes: a first portion forming one end of the air guide unit and coupled to the inner surface of the combustor liner; and a second portion forming another end of the air guide unit and disposed in the combustor liner, and a size of the first portion is different from a size of the second portion.

The air guide unit may further include: a third portion arranged at an inlet side of the air, and formed inclined with respect to the inner surface of the combustor liner; and a fourth portion arranged at an outlet side of the air, and formed perpendicular to the inner surface of the combustor liner.

A second flow port and a third flow port may be arranged in the third portion.

The second flow port may be formed as a plurality of holes at a position closer to the inner surface of the combustor liner than the third flow port.

The third flow port may be formed in a crescent shape along a circumference of the air guide unit.

A fourth flow port may be arranged in the fourth portion, and the fourth flow port may be formed as a plurality of holes.

A first flow port may be arranged in the second portion.

The air guide unit may inject air having passed through a deswirler, into the combustor liner.

In the air guide unit, the first portion may be formed in an elliptical shape, and the second portion may be formed in a circular shape.

In the air guide unit, a long diameter of the first portion may be greater than a diameter of the second portion.

In the air guide unit, the second portion may be arranged biased in a main flow direction of a combustion gas in the combustor liner with respect to the first portion.

The combustor liner and the air guide unit coupled to the combustor liner may be manufactured by stacking combustor liner parts output by a three-dimensional (3D) printer.

The first portion and the second portion may be formed in a waterdrop shape, the air guide unit may further include: a third portion arranged at an inlet side of the air, and formed inclined with respect to the inner surface of the combustor liner; and a fourth portion arranged at an outlet side of the air, and formed perpendicular to the inner surface of the combustor liner, and a pointed portion may be formed in the fourth portion.

Other aspects, features, and advantages other than those described above will become apparent from the following detailed description, the appended claims, and the accompanying drawings.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

The disclosure may include various embodiments and modifications, and certain embodiments thereof are illustrated in the drawings and will be described herein in detail. However, this is not intended to limit the disclosure to particular embodiments, and it should be understood as including all modifications, equivalents, and substitutes included in the spirit and scope of the disclosure. As used herein, expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. For example, the expression, “at least one of a, b, and c,” should be understood as including only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.

It will be understood that although terms such as “first” and “second” may be used herein to describe various elements, these elements should not be limited by these terms and these terms are only used to distinguish one element from another element.

Also, it will be understood that the terms “comprise,” “include,” and “have” used herein specify the presence of stated features or elements, but do not preclude the presence or addition of one or more other features or elements.

Sizes of elements in the drawings may be exaggerated for convenience of description. In other words, because the sizes and shapes of components in the drawings are arbitrarily illustrated for convenience of description, the disclosure is not limited thereto.

The x axis, the y axis, and the z axis are not limited to three axes of the rectangular coordinate system and may be interpreted in a broader sense. For example, the x-axis, y-axis, and z-axis may be perpendicular to each other or may refer to different directions that are not perpendicular to each other.

When a certain embodiment may be implemented differently, a particular process order may be performed differently from the described order. For example, two processes described in succession may be performed substantially at the same time or may be performed in an order opposite to the described order.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the disclosure. It will be understood that terms such as “comprise”, “include”, and “have”, when used herein, specify the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Hereinafter, a combustor according to an embodiment will be described with reference toFIGS.1A and1Bto 4.

FIGS.1A and1Billustrate a main flow direction in which air reacted with fuel in a combustor liner is discharged to a vane and a degree to which an air jet introduced into the combustor liner penetrates into a combustor, depending on whether there is an air guide unit, according to an embodiment.FIG.2illustrates a structure of a combustor according to an embodiment.FIG.3is a perspective view of region A ofFIG.2.FIG.4illustrates a shape of an air guide unit according to an embodiment.

Referring toFIGS.1A and1B to4, a combustor according to an embodiment may include a combustor case200, a combustor liner300which is arranged in the combustor case200and in which fuel is injected, and an air guide unit100that is hollow and is formed to protrude from an inner surface of the combustor liner300into the inside of the combustor liner300to inject air into the inside of the combustor liner300.

In this case, the air guide unit100may include a first portion100aforming one end of the air guide unit100and coupled to the inner surface of the combustor liner300, and a second portion100bforming another end of the air guide unit100and disposed in the combustor liner300, and the size of the first portion100ais different from the size of the second portion100b. In more detail, the first portion100amay have a greater internal area than the second portion100b.

FIGS.1A and1Bshow a jet-in-crossflow (JICF) that is the shape of a flow injected in a direction perpendicular to the direction of a main flow.FIGS.1A and1Billustrates a state in which a main flow proceeds in a liner10in a direction in which a vane is located and a state in which an air jet penetrates more deeply into the liner10through an air guide unit11formed inFIG.1B, than when there is no air guide unit as inFIG.1A.

Referring toFIGS.1A and1B, the JICF may be used in a combustor design in various forms. For example, the inner surface of a liner may be protected from high-temperature air through an effusion hole disposed adjacent to the inner surface of the liner, and an equivalent ratio suitable for the internal space of a combustor may be formed through a dilution hole to determine the flame temperature in a combustion chamber. The most representative design parameter of the JICF may be a momentum ratio J as represented in the following equation.
J=rhojet×ujet2/rho∞×u∞2

Here, “rho” and “u” denote the concentration and speed of a fluid, and “jet” and “∞” denote jet air and a main flow (crossflow), respectively.

In this case, the height at which the jet air penetrates into the main flow may increase as the momentum ratio J increases.

In the case of a small turbojet engine, an air guide unit11for increasing the penetration height may be added to separate the space in a combustion chamber as a flow structure.

That is, a penetration height h2of the jet air penetrating into the liner10in the case where the air guide unit11is added to the liner10as in the present embodiment as illustrated inFIG.1Bmay be greater than a penetration height h1of the jet air in the case where there is no air guide unit11as inFIG.1A.

Referring toFIG.2, in the combustor according to the embodiment, high-pressure air supplied from a compressor (not illustrated) may flow through a deswirler400into the space between the combustor case200and the combustor liner300. The air flowing into the space between the combustor case200and the combustor liner300may be supplied into the combustor liner300through the air guide unit100.

A flame FL may generated in the combustor liner300through a fuel spray FS injected from a slinger nozzle600that is rotating, and the air combusted in the combustor liner300as such may be discharged to a turbine (not illustrated) through a vane500. In this case, the combusted air in the combustor liner300may flow in a direction in which the vane500is disposed, and the direction may be defined as a main flow direction T in the combustor liner300.

In this case, the air supplied through the air guide unit100according to the present embodiment may be improved in the combustion efficiency due to an increase in the penetration height into the combustor liner300, compared to the air simply introduced into the combustor liner300through a perforated portion thereof. Such an increase in the combustion efficiency may be maximized by a particular shape of the air guide unit100according to the present embodiment. The particular shape of the air guide unit100will be described below.

Referring toFIG.3, the combustor liner300and the air guide unit100coupled to the combustor liner300may be manufactured by stacking combustor liner parts300a,300b, and300coutput by a three-dimensional (3D) printer.

Referring toFIG.4, the air guide unit100according to the present embodiment may be easily manufactured by stacking 3D printing materials from the first portion100ato the second portion100bin a 3D printing stack direction. That is, the air guide unit100according to the present embodiment may be an air guide structure capable of being manufactured by taking advantage of a 3D printing technique, and may be manufactured by stacking (contouring) from the first portion100a, which is an elliptical base, to the second portion100b, which is a circular upper end, at an angle in which the flow of air inside and outside the combustor liner300and the rotation direction thereof are considered. When a 3D printed product has a portion bent at 90° in the stacking direction, postprocessing may be essentially required (e.g., a support and the like should be stacked together), and thus, manufacturing based on 3D printing may be difficult.

Also, the combustor liner300may be easily manufactured without the need for postprocessing by using an additive manufacturing process of 3D printing to stack a plurality of combustor liner parts300a,300b, and300cforming the inner surface of the combustor liner300, and thus, combustor liners may be manufactured more efficiently and at lower costs, compared to the manufacturing technology of the related art in which combustor liner parts are welded one by one.

Hereinafter, a structure for forming an air guide unit according to an embodiment will be described in more detail with reference toFIGS.4to7. For the contents not illustrated inFIGS.4to7, reference may be made to the description ofFIGS.1to3.

FIG.5illustrates flow ports formed in an air guide unit according to an embodiment.FIG.6illustrates flow directions of air flowing from flow ports formed in an air guide unit according to an embodiment.FIG.7is a cross-sectional view taken along line B-B′ ofFIG.5.

Referring toFIGS.4to7, in the air guide unit100according to an embodiment, the first portion100amay be formed in an elliptical shape, and the second portion100bmay be formed in a circular shape. In this case, a long diameter D1of the first portion100amay be greater than a diameter D2of the second portion100b. The size of a hollow portion of the first portion100acoupled to the inner surface of the combustor liner300may be greater than the size of a hollow portion of the second portion100barranged in the combustor liner300. Thus, the air having passed through the deswirler400may more easily enter into the combustor liner300through the first portion100ahaving the relatively greater size.

The second portion100b, which is a portion through which air is discharged from the air guide unit100, may be formed in a direction in which the vane500is disposed. That is, the air guide unit100may be formed in an asymmetric shape, and the second portion100bmay be arranged in the main flow direction T of the combustor liner300with respect to the first portion100a. Accordingly, when air outside the combustor liner300enters into the combustor liner300, because the air may enter in a direction capable of meeting the main flow direction T in the combustor liner300, the pressure loss due to the collision between the air entering into the combustor liner300and the main flow in the combustor liner300may be minimized.

According to the present embodiment, the air guide unit100may include a third portion100carranged at an inlet side of the air and formed inclined with respect to the inner surface of the combustor liner300and a fourth portion100darranged at an outlet side of the air and formed perpendicular to the inner surface of the combustor liner300.

The third portion100cmay be referred to as windward. The third portion100cmay be formed inclined with respect to the inner surface of the combustor liner300to function as a guide for allowing the air located outside the combustor liner300to naturally enter into the air guide unit100to meet in the main flow direction T of the combustor liner300. The upward inclination may be formed in the main flow direction T around a portion where the inner surface of the combustor liner300and the third portion100cmeet each other.

The fourth portion100dmay be referred to as leeward. The fourth portion100dmay be formed perpendicular to the inner surface of the combustor liner300, and in the introduction direction of the air introduced into the air guide unit100, it may be formed at a 90-degree angle with respect to the inner surface of the combustor liner300such that the air discharged from the air guide unit100may not be bent.

Referring toFIGS.5and6, a first flow port110may be arranged at the second portion100b. Referring toFIG.6, a first flow f1may be formed from the first flow port110. The first flow port110may be a main flow port of the air guide unit100, and may allow the air outside the combustor liner300to penetrate deeply into the combustor liner300through a protrusion structure of the air guide unit100.

In the third portion100cformed to be gently inclined, a second flow port120formed closer to the inner surface of the combustor liner300than a third flow port130may be formed as a plurality of holes. Referring toFIG.6, a second flow f2may be formed from the second flow port120.

The plurality of holes forming the second flow port120may be windward effusion holes, and may perform a cooling function by supplying air along the surface of the air guide unit of the third portion100cformed to be gently inclined such that the inner surfaces of the air guide unit100and the combustor liner300may be protected from the high-temperature internal air. As such, when air is supplied along the surfaces of the combustor liner300and the air guide unit100, a layer cooling flow may be formed and thus a cooling layer may be formed at a surface portion of the combustor liner300and the air guide unit100.

In the third portion100cformed to be gently inclined, the third flow port130formed closer to the second portion100b, which is an end portion of the air guide unit100, than the second flow port120may be formed in a crescent-shaped slit structure along the circumference of the air guide unit100.

In order to allow more cooling air to be introduced into the second portion100bto protect the end portion of the air guide unit100, that is, the second portion100b, from the flame FL, the third flow port130may be opened with a greater area than the sum of the plurality of holes of the second flow port120, and both end portions of the second flow port120may be formed to face the second portion100b. The plurality holes of the second flow port0may be inclined in the direction of the second portion100bso that cooling air can be directed to the second portion100b.

A fourth flow port140formed as a plurality of holes may be arranged in the fourth portion100dthat is vertically formed. Because the fourth portion100dis formed in a cylindrical lateral shape formed perpendicular to the inner surface of the combustor liner300, and thus, the high-temperature gas in the combustor liner300and the fourth portion100dof the air guide unit100act as a non-streamlined object, that is, a bluff body, and a wake is formed at a portion where the fourth portion100dis disposed and accordingly a high-temperature area is formed, the fourth flow port140for cooling the high-temperature area may be formed as a plurality of holes in the fourth portion100d.

As such, the first flow port110may function as an air effusion hole to minimize the pressure loss of the air injected into the combustor liner300and improve the combustion efficiency thereof, and the second, third, and fourth flow ports120,130, and140may function as an air dilution hole to protect the surface portion of the combustor liner300and the air guide unit100from the high-temperature flame, thus providing an effect of improving the durability of the combustor.

FIG.8corresponds to region A ofFIG.2and illustrates a direction in which air flows according to the structure of a combustor liner and an air guide unit according to an embodiment.

Referring toFIG.8, the air (F) having passed between banana-shaped protrusion portions410of the deswirler400may enter the combustor liner300through a space200abetween the combustor case200and the combustor liner300. In this case, air may flow in a long-axis direction L of an ellipse formed by the first portion100aof the air guide unit100and may enter into the combustor liner300. Also, the air having entered into the combustor liner300may not completely follow the main flow direction T in the combustor liner300but may flow in the long-axis direction L of the air guide unit100and enter into the space between protrusion portions510of the vane500after passing by the first hole310and the second hole320. In this case, the longitudinal direction of the protrusion portions510of the vane500, that is, an inclination angle, may be formed to follow a flow direction, which is the longitudinal direction of the air guide unit100, having an angle “a” with respect to the main flow direction T. According to an embodiment, the longitudinal direction of the protrusion portions510may be greater than the angel “a” and smaller than 90°.

As such, the air having passed through the air guide unit100through the arrangement structure of the air guide unit100may not completely follow the main flow direction T but may flow in a direction parallel to the long-axis direction L of the air guide unit100. As an experimental example, in this case, an air flow direction angle “a” may be formed at about 12 degrees with respect to the main flow direction T.

As such, because the air guide unit100is arranged to be inclined by an angle “a” with respect to the main flow direction T, and the longitudinal direction of the air guide unit100arranged to be inclined is arranged to follow the longitudinal direction of the protrusion portions510of the vane500and accordingly the air flowing through the air guide unit100flows in accordance with the guide direction of the air guide unit100and naturally flows through the space between the protrusion portions510guided by the protrusion portions510of the vane500, the pressure loss of the air discharged to the vane500after entering the combustor liner300may be minimized.

Also, the air guide unit100may be arranged in a direction in which the air introduced into the combustor liner300according to the rotation direction of the slinger nozzle600may be discharged to the vane500while minimizing the pressure loss thereof.

As such, when the flow direction is formed to be inclined with respect to the main flow direction T, and thus, there is a rotation component in the flow of air, there may be an effect of increasing the residence time for the combustion gas to stay in the same volume of the combustor liner. This may be connected to the effect of improving the combustion efficiency.

Hereinafter, an air guide unit according to another embodiment will be described with reference toFIG.9. For the contents not described below, reference may be made to the contents described above.

FIG.9illustrates an air guide unit according to another embodiment.

Referring toFIG.9, in an air guide unit100′ according to another embodiment, a first portion100a′ and a second portion100b′ may be formed in a waterdrop shape, and as a result, a pointed portion100d′ may be formed at a fourth portion100d′.

As such, the shape of the air guide unit100′ may be formed in an airfoil shape having one side rounded and the other side pointed. This shape may be advantageous in that it be stacked from the first portion100a′ to the second portion100b′ by using a 3D printing stack manufacturing method.

Also, according to the present embodiment, because the pointed portion100d′1is formed at the fourth portion100d′ where a wake may be formed, a wake f′ occurring at the fourth portion100d′ may be reduced, and instead, a swirl flow may be generated to remove a high-temperature area in the fourth portion100d′, thereby protecting the air guide unit100′ and the combustor liner300in the corresponding portion from a high-temperature flame and securing the durability thereof.

Although the disclosure has been described with reference to embodiments illustrated in the drawings, the embodiments are merely examples. Those of ordinary skill in the art may fully understand that various modifications and other equivalent embodiments may be made from the embodiments. Thus, the true scope of the disclosure should be determined based on the appended claims.

Particular technical contents described in the embodiments are merely examples and do not limit the scope of the disclosure. In order to concisely and clearly describe the embodiments, descriptions of general technologies and configurations of the related art may have been omitted. Connections or connection members of lines between the elements illustrated in the drawings may illustratively represent functional connections and/or physical or logical connections and may be represented as various replaceable or additional functional connections, physical connections, or logical connections in an actual apparatus. Also, no element may be essential to the practice of the disclosure unless the element is particularly described as “essential” or “critical”.

In the description and claims, “the” or similar reference words may refer to both the singular and the plural unless otherwise specified. Also, unless otherwise specified herein, recitation of a range of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, and each separate value may be incorporated herein as if it was individually recited herein. Also, the operations of the method described herein may be performed in any suitable order unless otherwise specified herein or otherwise clearly contradicted by the context. The embodiments are not limited to the described order of the operations. All examples or illustrative terms (e.g., “such as”) used herein are merely intended to describe the technical concept of the disclosure in detail, and the scope of the disclosure is not limited by the examples or illustrative terms unless otherwise defined in the appended claims. Also, those of ordinary skill in the art may understand that various modifications, combinations, and changes may be made according to design conditions and factors within the scope of the appended claims or equivalents thereof.

In the combustor according to the above embodiments, the combustor liner may be more easily manufactured by manufacturing the combustor liner by using the 3D printer stack manufacturing method.

Also, in the combustor according to the embodiments, through the structure of the air guide unit based on the cooling design, the pressure loss of the air introduced into the combustor liner may be minimized and the combustion efficiency of the combustor may be improved.

Effects of the disclosure are not limited to the effects mentioned above, and other unmentioned effects may be clearly understood from the description of the appended claims by those of ordinary skill in the art.