JPH06330765A - Flame holding device of jet engine - Google Patents

Abstract

PURPOSE:To improve a thrust by improving a mixing property of fuel and air and providing effective combustion of the fuel in a flame holding device of a jet engine. CONSTITUTION:A mixer 23 formed into a corrugated tubular body having a plurality of irregular portions arranged in parallel to the axis of a combustion duct 6 and circumferentially is provided between a fuel nozzle 9 disposed in the combustion duct 6 through which air current passes and an ignition plug 10, while the irregular portions of the mixer 23 are formed so that the difference between the high and low portions is gradually increased toward the downstream of the axis of the combustion duct 6. Just in front of a confluence position of a combustion gas flow B generated in a combustor 4 and air current A flowing outside the combustion gas flow B are disposed so as to isolate the combustion gas flow B from air current A and the combustion gas flow B and air current A are alternately passed through the adjacent irregular portions of the mixer 23 to efficiently mix the combustion gas blow B with the air current A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame holding device for a jet engine.

[0002]

2. Description of the Related Art Jet engines used in airframes include gas turbine engines mainly used in the subsonic range and ramjet engines used in the supersonic range.

FIG. 4 shows a conventional example of the gas turbine engine 1. This gas turbine engine 1 includes a fan 2 that takes in air, a compressor 3 that compresses the taken-in air, a combustor 4 that mixes fuel with the compressed air and burns the same, and a combustor 4 that generates the air. An output turbine 5 that drives the fan 2 and the compressor 3 by the generated combustion gas is provided, and thrust is obtained by ejecting the combustion gas rearward through the exhaust pipe 6. It is known that the thrust can be improved by re-combusting the combustion gas in the exhaust pipe 6 and increasing the jet speed of the combustion gas. As a method of improving the thrust, the afterburner 7 is installed in the exhaust pipe 6. It is carried out.

The afterburner 7 is used for the output turbine 5
A plurality of annular flame stabilizers 8 having, for example, a triangular cross section are arranged in the exhaust pipe 6 disposed downstream of the flame retainer 8 with their apex angles toward the upstream side, and the upstream side of the flame stabilizers 8 A fuel nozzle 9 and a spark plug 10 downstream of the flame stabilizer 8. When the combustion gas is circulated around the flame stabilizer 8, a turbulent flow region X is formed in the wake of the flame stabilizer 8, and the mixing of the combustion gas and the fuel is promoted, so that the spark plug 1
Ignition property and flame holding property by 0 will be improved.

On the other hand, a ramjet engine, which is attracting attention as a jet engine used in a supersonic aircraft, compresses air by the ram pressure when the air flows into the engine at a high speed. . Therefore, the compressor is not required and the structure is extremely simple. Further, as the inflowing air speed increases, that is, the navigation speed of the airframe increases, the combustion efficiency can be improved. Research is underway as an engine for automobiles.

One of the problems associated with the ramjet engine is that the air flow in the combustion duct has a supersonic velocity, which makes it difficult to mix the fuel injected from the fuel nozzle with the air, resulting in ignitability and flame retention. Is low.
In order to solve this, as shown in FIG. 5, around the center body 12 arranged in the cylindrical combustion duct 11,
A plurality of annular gutters 13 (flame stabilizers) having a V-shaped or U-shaped vertical cross-section that opens toward the downstream side are arranged, and the fuel nozzle 9 is provided upstream of the gutter 13 and the spark plug 10 is provided downstream. It is devised to arrange. Then, by forming a recirculation zone Y in which the air flow is circulated at a subsonic speed downstream of the gutta 13, the fuel and air are mixed in the recirculation zone Y, and the recirculation zone Y is ignited. Stopper 1
By setting 0, the combustion state can be maintained.

[0007]

However, in the gas turbine engine 1 having the above structure, in order to promote the combustion by the afterburner 7, a part of the air taken in by the fan 2 is directly passed through the combustor 4 without passing through the combustor 4. It is guided into the exhaust pipe 6. However, this air flow A (fan flow) is formed outward with respect to the combustion gas flow B (core flow) and is circulated in parallel with the core flow B, so that the flame stabilizer 8 is used. The turbulent flow area formed is the fan flow A
And the core flow B, respectively, and it is difficult to improve the mutual mixing property of the fan flow A and the core flow B. Therefore, there is a problem that the amount of oxygen in the combustion gas cannot be increased and the combustion efficiency cannot be improved.

Further, the ramjet engine 1 having the above structure
When it is 4, although the recirculation region Y is formed by the gutta 13, the region is extremely small, and it is difficult to improve the mixing property of fuel and air and the thrust generated by the combustion of fuel. There is a problem.

The present invention has been made in view of the above-mentioned circumstances, and improves the mixing property of fuel and air and effectively burns the fuel to obtain high thrust in a jet engine. The purpose is to provide a device.

[0010]

In order to achieve the above object, the present invention proposes the following three means. A first means is to ignite a fuel nozzle for injecting fuel on the air flow in a combustion duct through which the air flow is inserted, and for igniting a mixed air flow of the fuel and the air flow, which is arranged at a space downstream of the fuel nozzle. In a jet engine including a spark plug, a corrugated plate-shaped tubular body is arranged between the fuel nozzle and the spark plug in parallel with an axis of the combustion duct and has a plurality of concavo-convex portions arranged in parallel in a circumferential direction thereof. A flame holding device for a jet engine is proposed, in which the mixer formed is provided and the uneven portion of the mixer is formed so as to gradually increase the height difference toward the downstream in the axial direction of the combustion duct. The second means is, in a jet engine in which a combustion duct is arranged downstream of the combustor, immediately before a position where the mixer joins the flow of the combustion gas generated in the combustor and the flow of the air which flows outside thereof. It proposes a flame holding device for a jet engine arranged to separate the combustion gas flow and the air flow. A third means proposes a flame holding device for a jet engine in which the uneven portion of the mixer is formed in a spiral shape that is gradually displaced in one direction around the axis of the combustion duct.

[0011]

According to the flame holding device for a jet engine according to the first aspect of the present invention, when the airflow is circulated around the mixer, the airflow disposed inside and outside the mixer is distributed along the surface of the mixer. Distributed. While these airflows are alternately passed through the uneven portions formed inside and outside the mixer in parallel, the airflows are made to flow at the same radial position due to an increase in the height difference of the uneven portions. Then, by being merged at the downstream side of the mixer, the airflow is agitated, and the mixing with the fuel jetted at the upstream side of the mixer is promoted. Further, according to the flame holding device for a jet engine according to the second means of the present invention, after the combustion gas flow and the air flow are circulated in and out of the mixer, respectively, and after they are circulated alternately in the adjacent uneven portions, Combined downstream of the mixer. This allows mixing of the combustion gas stream with the air stream,
Also, the mixing of the injected fuel with the fuel gas flow and the air flow is promoted upstream of the mixer. Also,
According to the flame holding device for a jet engine according to the third means of the present invention, the mixer mixes the air flow with the air flow to promote the mixing of the fuel and the air flow, and the uneven portion of the mixer is formed in a spiral shape. As a result, a swirl flow is generated in the wake of the mixer, and the combustion speed is improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a flame holding device for a jet engine according to the present invention will be described below with reference to FIGS. In this embodiment, the same parts as those of the conventional example shown in FIG.

This embodiment is a gas turbine engine 20.
(Jet engine), as shown in FIG. 1, a fan 2 for taking in air, a compressor 3 for compressing a part of the taken-in air, and a fuel mixed with the compressed air. An exhaust pipe 6 is provided with a combustor 4 for combustion, and an output turbine 5 for driving the fan 2 and the compressor 4 by the combustion gas generated by the combustor 4.
It is common to the conventional example shown in FIG. 4 in that the afterburner 21 is arranged in the (combustion duct). Also in the gas turbine engine 20 of the present embodiment, the core flow B through which the air flow taken in by the fan 2 is inserted through the combustor 4 and the tubular flow passage 22 radially outward of the core flow B are provided. The structure is such that it is branched into the fan flow A that is inserted and merged in the exhaust pipe 6. However, the gas turbine engine 20 of the present embodiment has the afterburner 2
The structure 1 is different from the conventional example.

The afterburner 21 employed in the flame holding device of the gas turbine engine 20 of the present embodiment has a tubular shape as a part of the inner wall 22a at the rear end of the inner wall 22a of the tubular passage 22 through which the fan flow A flows. It is configured by arranging the mixer 23 in the shape of a circle. The fuel nozzle 9 is arranged, for example, in the tubular flow path 22 located upstream of the mixer 23, and the spark plug 10 is arranged downstream of the mixer 23.

As shown in FIG. 2, the mixer 23 is a cylindrical member which is arranged concentrically and radially inward of the exhaust pipe 6, and is circumferentially spaced on its wall surface. By arranging a plurality of projecting portions 23a (uneven portions) radially inward, a concave portion 23b (uneven portion) formed between them
Together with this, it is formed as a corrugated tubular body as a whole. The projecting portion 23a gradually increases in projecting height from the end portion arranged on the upstream side of the mixer 23 toward the downstream in the longitudinal direction, and is gradually displaced around the axial center of the mixer 23 in one direction to form a spiral. It is formed in a twisted shape. In FIG. 2, reference numeral 23c is a flange portion for attaching the mixer 23 to the exhaust pipe 6.

The operation of the flame holding device of the gas turbine engine 20 constructed as above will be described below.
The airflow taken in by is divided into a fan flow A and a core flow B upstream of the compressor 3, the fan flow A is circulated in the tubular flow path 22, and the core flow B is input to the compressor 3. . The core flow B compressed by the compressor 3 is combusted in the combustor 4, then passed through the output turbine 5, and ejected into the exhaust pipe 6. Also, fan style A
Is passed through the tubular flow path 22 and directly ejected into the exhaust pipe 6.

Here, since the mixer 23 arranged at the rear end of the tubular flow path 22 is formed as a corrugated tubular body that projects a plurality of projecting portions 23a inward in the radial direction, the core flow B While flowing along the inner surface of the mixer 23 and the fan flow A along the outer surface of the mixer 23, the fan flow A is alternately flowed through the mixer 23 into the adjacent uneven portions 23a and 23b. They are merged at the rear end of the mixer 23. As a result, the core flow B and the fan flow A are efficiently mixed. The core flow B is a high-pressure combustion gas generated by the combustor 4 and contains a small amount of unburned oxygen, and the fan flow A is an unburned air flow. By mixing the fan flow A and the fan flow A by the mixer 23, a high-pressure air-fuel mixture containing a large amount of oxygen can be synthesized, and as a result, combustion in the exhaust pipe 6 is promoted.

Further, since the mixer 23 is formed in a spiral shape, the fan flow A and the core flow B, which are inserted through the mixer 23, are swirled in the exhaust pipe 6 by being given swirling force. The burning rate will be increased.
This makes it possible to reduce the length of the exhaust pipe 6 for performing desired combustion, and the jet engine 20
The weight can be reduced.

Next, a second embodiment of the flame holding device for a jet engine according to the present invention will be described with reference to FIG. As shown in FIG. 3, the flame holding device for a jet engine according to the present embodiment is used for a ramjet engine 30 used for supersonic flight, and is a cylinder that allows an air flow to pass along the longitudinal direction. In a rectangular combustion duct 11, a center body 12 for diverting an air flow, a fuel nozzle 9 for ejecting fuel along with the air flow, and the first for agitating the air flow.
Mixer 23 equivalent to that of the above embodiment, and an ignition plug 1 for igniting a mixture of fuel and air mixed by being stirred
0 and 0 are provided.

When the flame holding device of the ramjet engine 30 having the above-mentioned structure is used, the air flow formed in the combustion duct 11 is mixed in the mixer 2 arranged in the combustion duct 11.
3 is inserted at the upstream end of the mixer 23,
Airflow in and out of the mixer 23 (internal airflow B / external airflow A)
, And the flow is re-joined at the downstream end of the mixer 23. In this case, the airflows A and B divided by the upstream end of the mixer 23 are made to flow along the inner and outer surfaces of the mixer 23,
Since the mixer 23 is formed in a corrugated plate shape by the protruding portion 23a protruding inward in the radial direction, the internal airflow B and the external airflow A are adjacent to each other with the mixer 23 interposed therebetween.
It will be circulated alternately in a.23b. Further, since the mixer 23 is formed in a spiral shape, both air flows A and B are given a turning force and are deflected. When both air flows A and B pass through the downstream end of the mixer 23, the mixer 23 as a partition plate that separates the internal air flow B from the external air flow A is removed, and the internal air flow B and the external air flow A are separated from each other. Are joined again. At this time, the air flows A and B are agitated with each other due to the difference in the flow velocity and the flow direction generated by the separation.

As a result, the fuel injected in the upstream of the mixer 23 and placed on the airflows A and B has improved mixability into the airflows A and B due to the stirring of the airflows by the mixer 23, and the fuel is distributed downstream of the mixer 23. By the operation of the spark plug 10, the combustion is efficiently performed. Further, since the combustion velocity of the airflows A and B to which the swirling force is applied is increased, the combustion can be performed in a short distance downstream of the mixer 23. Thereby, the combustion duct 11
There is an advantage that the length of the engine can be shortened and the weight of the engine 30 can be reduced.

[0022]

As described above in detail, the flame holding device for the jet engine according to the first means of the present invention is provided between the fuel nozzle and the spark plug arranged in the combustion duct through which the air flow is inserted. , Providing a mixer formed in a corrugated tubular body by arranging a plurality of uneven portions in parallel with the axis of the combustion duct in the circumferential direction, and directing the uneven portion of the mixer toward the downstream in the axial direction of the combustion duct. Since it is formed so that the height difference is gradually increased, the following effects are achieved. When the airflow arranged inside and outside the mixer flows in the longitudinal direction of the mixer, the airflow is circulated in the uneven portions adjacent to each other with the mixer in between, and is efficiently mixed by being merged in the downstream of the mixer. It is possible to improve the ignitability and flame retention in the duct. As a result, the thrust due to the combustion of fuel can be efficiently extracted, and a jet engine with high thrust can be constructed. In the jet engine flame holding device according to the second means, in the jet engine in which the combustion duct is arranged downstream of the combustor, the mixer distributes the combustion gas flow generated in the combustor and the outside thereof. Since the combustion gas flow and the air flow are arranged just before the confluence position with the air flow to be separated, the combustion gas flow and the air flow are circulated in the adjacent irregularities of the mixer, and By being merged in the downstream, the combustion gas flow and the air flow can be efficiently mixed to improve the ignitability and flame holding property in the combustion duct, and the re-combustion of the combustion gas can be promoted. Has the effect. Further, in the flame stabilizing device for a jet engine according to the third means, since the uneven portion of the mixer is formed in a spiral shape which is gradually displaced in one direction around the axial line of the combustion duct, In addition to the effect, there is an effect that the combustion speed of the fuel is increased to shorten the combustion duct and the weight of the jet engine can be reduced.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a flame holding device for a jet engine according to a first embodiment of the present invention.

2 is a perspective view showing a mixer of the flame holding device of FIG. 1. FIG.

FIG. 3 is a vertical cross-sectional view showing a flame holding device for a ramjet engine according to a second embodiment of the present invention.

FIG. 4 is a vertical sectional view showing a gas turbine engine as a first conventional example of a flame holding device for a jet engine.

FIG. 5 is a vertical cross-sectional view showing a ramjet engine as a second conventional example of a flame holding device for a jet engine.

[Explanation of symbols]

 2 Fan 3 Compressor 4 Combustor 5 Output Turbine 6 Exhaust Pipe (Combustion Duct) 9 Fuel Nozzle 10 Spark Plug 11 Combustion Duct 20 Gas Turbine Engine (Jet Engine) 21 Afterburner 22 Cylindrical Channel 22a Inner Wall 23 Mixer 23a Projection ( Concavo-convex portion 23b Recessed portion (concavo-convex portion) 23c Flange portion 30 Ramjet engine (jet engine) A Fan flow (air flow) B Core flow (combustion gas flow)

Claims (3)

[Claims] 1. A fuel nozzle for injecting fuel along with an air flow in a combustion duct through which the air flow is inserted, and ignition for igniting a mixed air flow of fuel and air flow, which is arranged downstream of the fuel nozzle with a gap. In a jet engine including a plug, between the fuel nozzle and the spark plug, a plurality of uneven portions are arranged in parallel with the axis of the combustion duct and arranged in the circumferential direction in a corrugated tubular body. A flame holding device for a jet engine, characterized in that the mixer having the above structure is provided, and the uneven portion of the mixer is formed so as to gradually increase the height difference toward the downstream in the axial direction of the combustion duct. 2. A jet engine in which a combustion duct is arranged downstream of a combustor, wherein a mixer is provided immediately before a merging position of a combustion gas flow generated in the combustor and an air flow passed therethrough. 2. Arranged to separate the combustion gas stream and the air stream.
Flame retarding device for the jet engine described. 3. The mixer according to claim 1, wherein the uneven portion of the mixer is formed in a spiral shape that is gradually displaced in one direction around the axis of the combustion duct. Jet engine flame holding device.