JPH0791317A - Fuel mixing device - Google Patents

Abstract

PURPOSE:To provide a fuel mixing device capable of promoting mixing and enlarging a diffused region while reducing pressure losses. CONSTITUTION:In a fuel mixing device containing fuel struts 2 placed in a gas-passage formed between engine-wall faces 1A arranged on opposite sides, and fuel injection nozzles formed on the fuel struts 2, each of the fuel struts 2 is provided with a concave wall forming a concave face relative to the flow of gas, when the strut is cut by a plane parallel to the flow direction of the passage, and s fuel injection nozzle is formed so that it can discharge fuel in parallel with the tangent at the downstream side end part of the wall face forming cancave face. Thus, since the fuel is injected into longitudinal vortex generated on the concave wall face and discharged from the final end of the concave wall face, oxidizing agent and fuel are efficiently mixed by involving-in action of the vortex. Further, the fuel is injected tangentially at the final end of the concave wall face, the injecting direction of the fuel becomes the same as the direction of gas flow, pressure losses is reduced, and vertical injection and mixing region can be ensured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel mixing system applied to a subsonic or supersonic combustor.

[0002]

2. Description of the Related Art Conventionally, as a method of mixing and diffusing an oxidant and a fuel in a supersonic air flow, there is a "Combustion Test
d Thermal Analysis of Fuel Injection Struts of aSc
ramjet Combustor, ISABE 91-7133, (1991) ”, a fuel strut is used to vertically inject fuel into a mainstream from a rearward facing step provided at the rear of the fuel strut to mix and diffuse the oxidant and the fuel. There is a way to do it.

[0003]

In FIG. 10, the horizontal axis shows the longitudinal distance of the combustion chamber from the fuel injection position, and the vertical axis shows the mixing ratio of fuel and oxidizer. The origin of the figure is the fuel injection position. The mixing ratio here means B / A × 100, which is the ratio of the cross-sectional area A of a certain section perpendicular to the longitudinal direction of the combustion chamber to the area B of the fuel spreading in that section. In the above-mentioned conventional technique, since the fuel is injected perpendicularly to the oxidant air flow, the mixing (diffusion) region of the fuel into the oxidant air flow increases as shown in FIG. 10, but the pressure loss increases. Therefore, the performance of the combustor as a whole is significantly reduced. On the other hand, when the fuel is injected parallel to the flow of the oxidant, as shown in FIG. 10, the mixing region becomes narrow, but the pressure loss is suppressed. Further, since Kelvin-Helmholtz type unstable vortices have been conventionally used, sufficient mixing cannot be performed.

It is an object of the present invention to provide a fuel mixing system which can promote mixing and increase the diffusion area while suppressing pressure loss.

[0005]

The above object is to provide a fuel diffusing means provided in a gas flow path containing an oxidant, and a fuel supply for supplying a fuel to the gas whose flow is deflected by the fuel diffusing means. A fuel mixing device including means, wherein the fuel diffusing means has a wall surface whose cross section taken along a plane parallel to the flow direction of the flow path is concave with respect to the flow of the gas; The supply means is achieved by including a fuel injection port that discharges the fuel substantially parallel to the tangent line of the downstream end of the concave wall surface.

[0006]

The angle between the tangent line drawn to a point on the surface in contact with the air flow and the direction of the air flow in a cross section cut by a plane parallel to the air flow direction is such that the point is from the upstream side of the air flow. When an object having a surface that becomes larger as it moves downstream (hereinafter referred to as a concave surface) is placed in the airflow, a vertical vortex 19 having an axis in the flow direction is formed on the concave wall as shown in FIG.
Occurs. This longitudinal vortex develops downstream, and is finally discharged from the final end of the concave surface into the main stream. At this time, the ejection direction of the fluid at the final end of the concave surface is most in the transverse direction as compared with the case where another shape (for example, a blunt section 18 or a wedge 17 in sectional shape) is adopted as shown in FIG. Therefore, when an object having such a concave surface is arranged in the oxidant air flow and fuel is injected in the tangential direction of the concave surface from the downstream end of the concave surface portion, the injected fuel is accompanied by the vertical vortex. Since it spreads into the oxidant air flow (main flow), the diffusion area of the fuel into the oxidant air flow (main flow) expands, and moreover, the fuel is caught in the vertical vortex discharged from the concave wall. The oxidizer and fuel mix efficiently. Further, since the fuel is injected tangentially at the final end of the concave surface, the injection direction of the fuel becomes the same as the direction of the air flow, and the same effect as parallel injection can be obtained. In fact, as shown in FIG. 10, there is an effect that a mixing region equivalent to that of the conventional vertical injection can be secured and the pressure loss can be suppressed. The velocity of the airflow may be subsonic or supersonic.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment in which the present invention is applied to a supersonic air suction type engine. The illustrated engine is composed of an engine main body 1 that is arranged opposite to each other and has wall surfaces 1A parallel to each other that form a flow path for the oxidant, and an oxidizer that is sandwiched between two wall surfaces 1A of the engine main body 1. The fuel strut body 2 is disposed in the flow path. The fuel strut body 2 is arranged in two stages so that the axis thereof is substantially parallel to the axis of the flow passage. Also,
The wall surface 1A forming the flow path of the engine body 1 and the outer surface of the fuel strut body 2 are both perpendicular to the paper surface.

The fuel strut body 2 is the engine body 1
Has a cross section cut by a plane perpendicular to the wall surface 1A and parallel to the flow channel axis, and has a pointed shape toward the upstream side. The tangent line drawn to a point of the pointed cross section and the flow channel axis form The corner has a surface (hereinafter referred to as a concave surface) such that the certain point increases as it moves from the upstream side to the downstream side of the air flow. The cross section of the fuel strut body 2 is symmetrical with respect to the center line of the fuel strut body 2 in the flow axis direction.

According to the above construction, when the supersonic airflow taken into the engine body 1 from the direction of the arrow 3 in the figure reaches the fuel strut 2, the wall surface of the fuel strut 2 has a concave surface, which is shown in FIG. As a result, a vertical vortex is generated on the surface. This will be described below with reference to FIG. FIG. 2 shows a half of a cross section of the fuel strut 2 taken along a plane perpendicular to the wall surface of the engine body 1 and parallel to the flow axis (the other half is line-symmetric with respect to the axis 20 with respect to the illustrated portion). .

The fuel strut 2 has a concave wall 4 on the upstream side, and a concave final end wall 5 extending at a downstream end of the concave wall 4 in a direction perpendicular to the axis 20 and toward the axis 20. 5 has a rearward facing step wall 6 connected to the end of the rearward facing stepping wall 5 parallel to the axis 20 and parallel to the flow passage wall surface of the engine body 1, and the downstream end of the rearward facing step wall 6 is the concave final end wall 5. It is connected to a parallel rearward facing step end wall 7. The rearward facing step end wall 7 forms the downstream end of the fuel strut 2. A chamber 10 connected to an external fuel supply means is formed inside the concave surface of the fuel strut 2, and the chamber 10 is connected to a fuel injection port 8 formed near a concave downstream end of the concave final end wall 5. The fuel passages 10A parallel to the surface of the concave end portion communicate with each other.

The vertical vortices generated on the concave surface develop downstream on the concave wall 4 and are finally discharged from the final end of the concave surface to the oxidant flow path. On the other hand, the fuel supplied from the external fuel supply means is injected through the chamber 10 from the fuel injection port 8 provided in the concave final end wall 5 in the concave tangential direction 11 at an angle α. The angle α is an angle formed by the concave surface tangential direction 11 and the axis 20. At this time, the fuel is injected into the vertical vortex discharged from the final end of the concave surface, so that the fuel and the mainstream oxidizer are well mixed by the entrainment motion of the vortex. Further, as shown in FIG. 9, the diffusion direction of the fuel is more in the transverse direction (direction closer to the wall surface 1A of the engine 1) than in the other shapes, so that the mixing region formed behind the fuel injection port 8 becomes wider. At the final end of the concave surface, the oxidant flowing along the concave wall 4 and the fuel discharged from the fuel injection port 8 are discharged in the same direction, so that the pressure loss can be suppressed.

In the example shown in FIG. 1, the concave wall 4 is formed in the fuel strut 2 arranged in the flow path of the oxidant. As shown in FIG. The concave wall 4 may be formed on the wall surface 1A of the main body. At this time, the rearward facing step wall 6 is the wall surface 1 of the engine body.
It will be A. Also in this case, since vertical vortices are generated on the concave wall 4, fuel may be injected tangentially at the final end of the concave surface. The effect is similar to that of the case of FIG.

Next, a second embodiment according to the present invention will be described with reference to FIG. In the figure, the same reference numerals as those used in the first embodiment denote the same members. The difference of the present embodiment from the first embodiment is that a plurality of slits or holes 12 are provided along the vertical vortex generated on the concave wall 4 and are communicated with the chamber 10 from the concave wall 4 top. It is also that the fuel is jetted out. That is, the fuel is ejected in the direction of the arrow 13 into the vertical vortex developed on the concave wall 4.
The ejected fuel is efficiently mixed with the oxidant by the entrainment motion of the vortex. Therefore, the air-fuel mixture can be formed in advance on the concave wall 4 before injecting the fuel from the fuel injection port 8 provided in the concave final end wall 5. In this case, the same effect as that of the first embodiment can be obtained, and the air-fuel mixture that is more thoroughly mixed than that of the first embodiment can be formed. Hole 12
For this, a large number of single holes may be provided, but the corresponding portion may be made of a porous material and ejected from a large number of holes. Further, even when the concave wall 4 is formed as a part of a certain wall surface as shown in FIG. 6, slits or holes 12 are provided along the vertical vortex generated on the concave wall 4, and these are communicated with the chamber 10. The same effect can be obtained by injecting the fuel also from above the concave wall 4.

Next, a third embodiment according to the present invention will be described with reference to FIG. In the figure, the same reference numerals as in the first embodiment indicate the same members. The difference of this embodiment from the second embodiment is that another fuel injection means is provided. That is, the fuel supplied from the external fuel supply means, in addition to being ejected on the concave wall, passes through the chamber 10 and is tangentially injected from the fuel injection port 8 of the concave final end wall 5 on the one side and the rearward step on the other side. Fuel is injected in a direction 14 parallel to the axis 20 from a fuel injection port 9 provided in the final end wall 7.
In this embodiment, the same effect as the second embodiment can be obtained.
Further, when the concave wall 4 is formed as a part of a certain wall surface as shown in FIG. 7, even if the fuel injection port 9 for injecting fuel in the direction 14 parallel to the axis 20 is provided, the same effect can be obtained.
FIG. 7 is an example in which another fuel injection port 9 is provided in the concave final end wall 7. Since the fuel is injected from the fuel injection port 9 in the direction of the arrow 14 along the rearward step wall 6, that is, the wall surface of the inner wall of the combustion chamber, the film cooling effect of the inner wall of the combustion chamber can be obtained together. Although the fuel injection port 8 and the fuel injection port 9 are connected to the same external fuel supply means in FIGS. 4 and 7, they may be connected to different fuel supply means.

[0015]

According to the present invention, since the fuel is injected while the vertical vortex generated on the concave wall is discharged from the final end of the concave surface, the oxidizer and the fuel are efficiently mixed by the entrainment motion of the vortex. be able to. Further, since the fuel is injected tangentially at the final end of the concave surface, the direction of injection of the fuel becomes the same as the direction of the oxidant air flow, and it is possible to obtain the effect of suppressing the pressure loss and ensuring a mixing region similar to that of vertical injection.

[Brief description of drawings]

FIG. 1 is a sectional view showing a part of a supersonic air suction type engine which is a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a main part of FIG.

FIG. 3 is a sectional view of a fuel strut showing a second embodiment of the present invention.

FIG. 4 is a sectional view of a fuel strut showing a third embodiment of the present invention.

FIG. 5 is a sectional view showing a modification of the first embodiment of the present invention.

FIG. 6 is a sectional view showing a modification of the second embodiment of the present invention.

FIG. 7 is a sectional view showing a modification of the third embodiment of the present invention.

FIG. 8 is a perspective view showing a generation state of a vertical vortex.

FIG. 9 is an explanatory diagram showing changes in the velocity vector at the terminal end with respect to the shape of the wall surface.

FIG. 10 is an explanatory diagram showing changes in the mixing ratio.

[Explanation of symbols]

1 Supersonic Air Suction Engine 1A Engine Wall 2 Fuel Strut 3 Air Flow Direction 4 Concave Wall 5 Concave Final End Wall 6 Rearward Step Wall 7 Rearward Step Final End Wall 8 Fuel Injector 9 Fuel Injector 10 Chamber 10A Fuel Flow Road 11 Fuel injection direction 12 Slit or hole 13 Fuel injection direction 14 Fuel injection direction 15 Wedge injection direction 16 Blunt injection direction 17 Wedge shape 18 Blunt shape 19 Longitudinal vortex

Claims (6)

[Claims] 1. A fuel mixing device comprising: a fuel diffusing means provided in a flow path of a gas containing an oxidant; and a fuel supplying means for supplying a fuel to the gas whose flow is deflected by the fuel diffusing means. In the above, the fuel diffusion means has a cross section cut by a plane parallel to the flow direction of the flow path, and the fuel supply means has a concave wall surface, and the fuel supply means has the concave wall surface. And a fuel injection port for discharging the fuel substantially parallel to the tangent line of the downstream end of the fuel mixing device. 2. A fuel mixing apparatus comprising: a fuel diffusing means provided in a flow path of a gas containing an oxidant; and a fuel supplying means for supplying a fuel to the gas whose flow is deflected by the fuel diffusing means. In the fuel mixture according to the invention, the fuel diffusing means has a wall surface that generates a vertical vortex of the gas extending in the gas flow direction, and the fuel supply means has a fuel injection port for injecting fuel into the generated vertical vortex. apparatus. 3. The fuel mixing device according to claim 2, wherein the fuel diffusing means has a wall surface whose cross section taken along a plane parallel to the flow direction of the flow path is concave with respect to the gas flow. Characteristic fuel mixing device. 4. The fuel mixing device according to claim 1, wherein the fuel supply means for supplying fuel supplies the fuel through the inside of the fuel mixing device from the downstream end of the concave portion to the tangential direction of the concave surface. A fuel mixing device having an injection port for injecting into a fuel. 5. The fuel mixing device according to any one of claims 1 to 4, wherein the fuel supply means for supplying the fuel has an ejection port for ejecting the fuel from the surface of the concave portion through the inside of the fuel mixing device. A fuel mixing device. 6. The fuel mixing device according to claim 5, wherein the ejection port ejecting from the surface of the concave portion is a slit or a porous hole provided in the air flow direction. .