CN110822480A - Ignition device and scramjet engine in a supersonic cavity combustion chamber - Google Patents

Abstract

The invention provides an ignition device in a supersonic concave cavity combustion chamber and a scramjet engine. The fuel jet holes and the concave cavity are arranged in the supersonic combustion chamber, the fuel jet holes are arranged at the upstream of the concave cavity, and the fuel injected by the fuel jet holes is transmitted along the direction of supersonic airflow transmission in a main flow passage of the supersonic combustion chamber; the cavity bottom wall is obliquely provided with a guide plate along the direction of supersonic air flow propagation in the main flow passage, the lower end of the guide plate is connected to the cavity bottom wall, the lower end of the guide plate is provided with a gap, and the cavity bottom wall below the inner side of the guide plate is provided with a spark plug for ignition. The invention applies the guide plate to the interior of the concave cavity to improve the local flow velocity and the equivalence ratio in the concave cavity, thereby realizing the ignition enhancement effect.

Description

Ignition device and scramjet engine in a supersonic cavity combustion chamber

technical field

The invention relates to the technical field of scramjet engine design, in particular to an ignition device in a supersonic concave cavity combustion chamber and a scramjet engine.

Background technique

Cavity flame holders are currently widely used in scramjet combustion chambers. The supersonic airflow flowing through the cavity will form a recirculation zone in the cavity, which can make the flame stay in it all the time, and continue to ignite the upstream fuel as a new ignition source, so as to achieve flame stabilization. The cavity can integrate fuel injection, mixing enhancement and flame stabilization in the supersonic combustion chamber, and plays an important role in improving the performance of the scramjet.

The fuel injection/ignition/flame stabilization/cooling integrated cavity is common in engineering at present. It includes the integration of fuel injection, ignition and flame stabilization. The cavity is used as the basic configuration. The cavity is upstream or/and the bottom of the cavity. The fuel is injected, and the torch/plasma igniter is also installed at the bottom of the cavity.

The publication number is CN104764045A, which discloses a supersonic combustion chamber cavity ignition device and a scramjet engine, which is an invention patent previously applied for by the applicant. It discloses a triangular airfoil ignition device used on a concave cavity flame stabilizer in a supersonic airflow. The triangular airfoil ignition device is mainly arranged on the bottom wall of the concave cavity, and the shape structure of the triangular airfoil is reasonably arranged, Change the transport process of the fuel with the airflow in the cavity, so as to alleviate the rich combustion environment near the spark plug and enhance the local mixing of fuel and air. In practical applications, it is found that the defects of this technical solution are: the complex flow field structure inside the cavity is difficult to ensure that there is a suitable local velocity and local equivalence ratio near the ignition position, which is not conducive to the formation and development of the initial fire nucleus after the ignition of the spark plug, and it is easy to Ignition failure. Specifically, a spark plug is provided on the bottom surface of the concave cavity, and a baffle plate is provided in the downstream direction of the spark plug. When the spark plug is ignited, the initial fire nucleus formed at the ignition position cannot directly propagate downstream along the bottom surface of the concave cavity due to the blocking effect, so that the fire nucleus experiences more The airflow dissipation effect is easy to ignite and fail.

SUMMARY OF THE INVENTION

The invention provides an ignition device in a supersonic concave combustion chamber and a scramjet engine. In the present invention, the deflector is applied inside the cavity to improve the local flow velocity and the equivalence ratio inside the cavity, thereby realizing the ignition enhancement effect.

For realizing the purpose of the present invention, adopt following technical scheme to realize:

An ignition device in a supersonic concave combustion chamber is provided with a fuel injection hole and a concave cavity in the supersonic combustion chamber, the fuel injection hole is arranged upstream of the concave cavity, and the fuel injected from the fuel injection hole follows the supersonic speed in the main channel of the supersonic combustion chamber. The direction of air flow propagation;

On the bottom wall of the cavity, along the direction of supersonic airflow propagation in the main channel, the supersonic airflow in the main channel is inclined and provided with a deflector, the lower end of the deflector is connected to the bottom wall of the cavity, and the lower end of the deflector is provided with a gap, A spark plug for ignition is arranged on the bottom wall of the cavity below the inner side of the deflector.

In the present invention, the fuel injected from the fuel injection holes is entrained into the cavity, and under the action of the deflector in the cavity, part of the fuel flows into the area below the inner side of the deflector and resides in it. The existence of the area under the inner side of the deflector allows the formation of a local low-speed recirculation zone, and at the same time, the fuel can be retained and the local equivalence ratio of the fuel can be improved, which is beneficial to the formation and residence of the initial fire nucleus after the ignition of the spark plug under the inner side of the deflector. The lower end of the plate is provided with a gap, and the fire core can propagate along the bottom wall of the cavity to the front wall of the cavity through the gap, so as to facilitate the propagation of the initial fire core.

As a preferred technical solution of the present invention, the bottom side wall of the lower end of the deflector is connected to the bottom wall of the cavity, and a gap is formed on the lower end of the deflector or on the deflector near the lower end of the deflector.

As a preferred technical solution of the present invention, connecting seats are provided on both sides of the lower end of the deflector, and are connected to the bottom wall of the cavity through the connecting seats on both sides, and a line is formed between the middle part of the lower end of the deflector and the bottom wall of the cavity gap.

As a preferred technical solution of the present invention, the length direction of the deflector is parallel to the propagation direction of the supersonic airflow in the main channel, and the spark plug is arranged on the center line in the length direction of the deflector.

As a preferred technical solution of the present invention, the length direction of the cavity is parallel to the propagation direction of the supersonic airflow in the main channel, and the cavity has a front wall and a rear wall in the length direction of the cavity. The front wall of the cavity is perpendicular to the direction of propagation of supersonic airflow in the main channel, and the rear wall of the cavity is inclined along the direction of propagation of supersonic airflow in the main channel, preferably, the inclination angle is 45 degrees.

As a preferred technical solution of the present invention, the deflector includes an inclined support plate and a top side plate, the lower end of the inclined support plate is connected to the bottom wall of the cavity, and the lower end of the inclined support plate is provided with a slit, and the inclined support plate follows the The supersonic airflow propagation direction in the main channel is inclined, the upper end of the inclined support plate is connected with one end of the top side plate, and the extension direction of the top side plate is consistent with the supersonic airflow propagation direction in the main channel.

As a preferred technical solution of the present invention, the internal angle between the inclined support plate and the top side plate is 120°-150°.

As a preferred technical solution of the present invention, the longitudinal direction of the slit is parallel to the width direction of the baffle. The length of the slit is 80%-95% of the width of the guide plate, and the width of the slit is 1 mm to 5 mm.

The structure of the deflector of the present invention is not limited, it can be a flat plate arranged obliquely, or a curved plate such as a curved plate arranged obliquely, or it can be designed to be connected by multiple flat plates or/and curved plates as required. One-piece folding plate.

A scramjet engine includes a supersonic combustion chamber, and an ignition device in the supersonic concave combustion chamber according to any one of the above technical solutions is arranged in the supersonic combustion chamber.

The advantages of the present invention are:

The invention provides an ignition device and a scramjet engine in a supersonic concave cavity combustion chamber, which solves the problem that the local fuel equivalence ratio and local flow velocity at the ignition position in the concave cavity by injecting fuel on the upstream wall of the concave cavity are unfavorable for the initial ignition. For the difficult problem of formation and development of the nucleus, a deflector device is installed on the bottom wall of the cavity to allow the fire nucleus to reside and develop in it. The invention mainly can satisfy reliable ignition and combustion in the concave cavity under Ma6 flight condition, meanwhile, the device will not cause total pressure loss by being arranged in the concave cavity, and has no great influence on the flame stabilization process.

Under the condition of injecting fuel upstream of the cavity, the invention utilizes a baffle plate on the bottom wall of the cavity to form a local low-speed recirculation zone inside the baffle plate and at the same time retain fuel to improve the fuel equivalence ratio, thereby facilitating ignition.

The lower end of the deflector of the present invention is connected to the bottom wall of the cavity, and the lower end of the deflector is provided with a gap, so as to facilitate the propagation of the initial fire nucleus along the bottom wall of the cavity through the gap to the front wall of the cavity.

The structure of the deflector of the present invention is not limited, it can be a flat plate arranged obliquely, or a curved plate such as a curved plate arranged obliquely, or it can be designed to be connected by multiple flat plates or/and curved plates as required. One-piece folding plate. The baffle is arranged on the bottom wall of the cavity and the shape structure of the baffle is reasonably arranged to improve the flow field structure near the ignition position and form a local rich-burning recirculation area to facilitate the formation and propagation of the initial fire nucleus. The structure of the deflector is simple and easy to manufacture. The arrangement of the deflector only covers the partial recirculation zone structure inside the concave cavity, and does not affect the entire concave cavity recirculation zone structure, thereby maintaining the flame stability performance of the concave cavity.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are just some embodiments of the present invention, and for ordinary skill in the art, other drawings can also be obtained according to these drawings without any creative effort.

1 is a schematic structural diagram of Embodiment 1 of the present invention;

2 is a schematic structural diagram of a deflector used in Embodiment 1 of the present invention;

3 is a schematic structural diagram of Embodiment 2 of the present invention

FIG. 4 is a diagram showing the effect of the deflector on the fuel transport process in the cavity.

Labels in the figure:

1. cavity; 2. fuel injection hole; 3. deflector; 4. ignition plug; 5. bottom wall of cavity; 6. front wall of cavity; 7. rear wall of cavity; 8. gap; 9. inclined Support plate; 10. Top side plate; 11. Connecting seat.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Referring to FIG. 1 , it is a schematic structural diagram of Embodiment 1 of the present invention.

An ignition device in a supersonic concave cavity combustion chamber, a fuel injection hole 2 and a concave cavity 1 are arranged in the supersonic combustion chamber, the fuel injection hole 2 is arranged upstream of the concave cavity 1, and the fuel injected by the fuel injection hole 2 burns with the supersonic speed. The direction of propagation of supersonic airflow in the main channel of the chamber.

The length direction of the cavity 1 is parallel to the propagation direction of the supersonic airflow in the main channel. In the length direction of the cavity 1 , the cavity 1 has a cavity front wall 6 and a cavity rear wall 7 . The bottom wall 5 of the cavity is provided with a deflector 3 inclined along the direction in which the supersonic airflow propagates in the main channel. In this embodiment, the deflector 3 includes an inclined support plate 9 and a top side plate 10 . The lower end of the inclined support plate 9 is connected to the bottom wall 5 of the cavity and a slot 8 is provided at the lower end of the inclined support plate 9 . The two sides of the lower end of the inclined support plate 9 are provided with connecting seats 11 , which are connected to the bottom wall 5 of the cavity through the connecting seats 11 on both sides, and a gap 8 is formed between the middle part of the lower end of the inclined support plate 9 and the bottom wall 5 of the cavity. .

The inclined support plate 9 is inclined along the direction of supersonic airflow propagation in the main channel, the upper end of the inclined support plate 9 is integrated with one end of the top side plate 10, and the extension direction of the other end of the top side plate 10 is the direction of the supersonic airflow in the main channel. set the same. A spark plug 4 for ignition is arranged on the bottom wall 5 of the cavity below the inner side of the deflector 3 . Preferably, the length direction of the deflector 3 is parallel to the propagation direction of the supersonic airflow in the main channel, and the spark plug 4 is arranged on the center line of the deflector 3 in the length direction.

FIG. 2 is a schematic structural diagram of a deflector used in Embodiment 1 of the present invention. The deflector 3 includes an inclined support plate 9 and a top side plate 10 . The internal angle between the inclined support plate 9 and the top side plate 10 is 135 degrees. The thickness of the deflector is 2mm, the width of the deflector is 30mm, the length of the deflector is 15mm, and the height of the deflector is 12mm. The lower end of the deflector is connected to the bottom wall 5 of the cavity through two connecting seats 11 with a height of 2 mm on both sides.

Referring to FIG. 3 , it is a schematic structural diagram of Embodiment 2 of the present invention.

An ignition device in a supersonic concave cavity combustion chamber, a fuel injection hole 2 and a concave cavity 1 are arranged in the supersonic combustion chamber, the fuel injection hole 2 is arranged upstream of the concave cavity 1, and the fuel injected by the fuel injection hole 2 burns with the supersonic speed. The direction of propagation of supersonic airflow in the main channel of the chamber.

The length direction of the cavity 1 is parallel to the propagation direction of the supersonic airflow in the main channel. In the length direction of the cavity 1 , the cavity 1 has a cavity front wall 6 and a cavity rear wall 7 . The front wall 6 of the cavity is perpendicular to the direction of propagation of supersonic airflow in the main channel, and the rear wall 7 of the cavity is inclined along the direction of propagation of supersonic airflow in the main channel. In practical applications, the form of the concave cavity is not limited, and it can be any form of concave cavity in the prior art, such as a rectangular concave cavity.

The bottom wall 5 of the cavity is provided with a deflector 3 inclined along the direction in which the supersonic airflow propagates in the main channel. In this embodiment, the lower end of the deflector 3 is connected to the bottom wall 5 of the cavity by welding or clamping, and a slit 8 is laterally opened on the deflector 3 near the lower end of the deflector 3 . A spark plug 4 for ignition is arranged on the bottom wall 5 of the cavity below the inner side of the deflector 3 .

FIG. 4 is a diagram showing the effect of the deflector on the fuel transport process in the cavity. When the fuel injected from the fuel injection hole 2 passes through the cavity 1, the fuel is entrained into the cavity 1. Under the action of the baffle plate 3 in the cavity 1, part of the fuel flows into the area below the inner side of the baffle plate 3 and is contained in the cavity 1. Dwelling, due to the existence of the deflector 3, the area below the inner side of the deflector 3 forms a local low-speed recirculation zone and at the same time retains the fuel to increase the fuel equivalence ratio, which is beneficial to the ignition of the spark plug under the inner side of the deflector. Form and stay. The lower end of the deflector 3 is provided with a slit 8, and the fire nucleus propagates along the bottom wall 5 of the cavity to the front wall 6 of the cavity through the slit 8, so as to facilitate the propagation of the initial fire nucleus.

Example 3:

A scramjet engine includes a supersonic combustion chamber, and an ignition device in the supersonic concave combustion chamber according to any one of the above technical solutions is arranged in the supersonic combustion chamber.

When the lateral fuel injection scheme upstream of the cavity is adopted, the position where the local velocity of the bottom wall of the cavity is fast occurs at the trailing edge of the cavity, where the local fuel equivalence ratio is also high; while the position at the bottom wall of the cavity where the local velocity is slow is usually Occurs at the leading edge and middle of the cavity, where the local fuel equivalence ratio is low. Therefore, it is difficult to ensure that the local velocity and local equivalence ratio are suitable when the fuel flows through the ignition position of the bottom wall of the cavity with the airflow, and the problems of ignition difficulty and flameout are prone to occur. In the present invention, a deflector device is installed above the ignition position on the bottom wall of the cavity. Under the condition of fuel injection upstream of the same cavity, a partial return area can be formed through the deflector to reduce the airflow speed, and the fuel can be retained in the deflector. Provides a local equivalence ratio, and the gap between the deflector and the bottom wall of the cavity can ensure the exchange of fuel and air mass and provide an opening direction for the development of the initial fire nucleus to the front edge of the cavity, which enhances the ignition under supersonic flow conditions. enhancement.

In the present invention, a deflector with a certain angle, width and shape is arranged on the bottom wall of the cavity to change the transport process of the fuel in the cavity with the shear layer, and to enhance the mixing between fuel and air, thereby enhancing the concave cavity. The effect of cavity ignition capability.

In summary, although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person of ordinary skill in the art, without departing from the spirit and scope of the present invention, can make various modifications. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims (10)

1. An ignition device in a supersonic concave cavity combustion chamber is characterized in that: the fuel jet holes and the concave cavity are arranged in the supersonic combustion chamber, the fuel jet holes are arranged at the upstream of the concave cavity, and the fuel injected by the fuel jet holes is transmitted along the direction of supersonic airflow transmission in a main flow passage of the supersonic combustion chamber; the cavity bottom wall is obliquely provided with a guide plate along the direction of supersonic air flow propagation in the main flow passage, the lower end of the guide plate is connected to the cavity bottom wall, the lower end of the guide plate is provided with a gap, and the cavity bottom wall below the inner side of the guide plate is provided with a spark plug for ignition.

2. An ignition device in a supersonic cavity combustion chamber as defined in claim 1, wherein: the fuel entrainment that fuel orifice spouts gets into the cavity, under the effect of the guide plate in the cavity, part fuel flows into the inboard below region of guide plate and dwells wherein, because the existence of guide plate makes the inboard below region of guide plate when forming local low-speed backward flow district and dwell fuel and improve the local equivalence ratio of fuel, thereby do benefit to the formation and the dwell of the initial flame kernel after the spark plug ignition of the inboard below of guide plate, the lower extreme of guide plate is equipped with a gap, the flame kernel can pass the gap along the cavity diapire and propagate to the cavity antetheca, thereby do benefit to the propagation of initial flame kernel.

3. An ignition device in a supersonic cavity combustion chamber as defined in claim 1, wherein: the bottom side wall of the lower end of the guide plate is connected to the bottom wall of the concave cavity, and a gap is formed in the lower end of the guide plate or the guide plate close to the lower end of the guide plate.

4. An ignition device in a supersonic cavity combustion chamber as defined in claim 1, wherein: the lower extreme both sides of guide plate are equipped with the connecting seat, are connected through the connecting seat and the cavity diapire of both sides, form a gap between the lower extreme middle part of guide plate and the cavity diapire.

5. An ignition device in a supersonic cavity combustion chamber as defined in any one of claims 1 to 4, wherein: the length direction of the guide plate is parallel to the propagation direction of supersonic air flow in the main flow channel, and the spark plug is arranged on the middle line of the guide plate in the length direction.

6. An ignition device in a supersonic cavity combustion chamber as set forth in claim 5, wherein: the length direction of the concave cavity is parallel to the propagation direction of the supersonic speed airflow in the main flow channel, and the concave cavity is provided with a concave cavity front wall and a concave cavity rear wall in the length direction of the concave cavity; the cavity front wall is perpendicular to the direction of supersonic air flow propagation in the main flow channel, and the cavity rear wall is obliquely arranged along the direction of supersonic air flow propagation in the main flow channel, wherein the inclination angle is 45 degrees.

7. The ignition device in a supersonic cavity combustion chamber as set forth in claim 1, wherein: the guide plate includes tilt support board and top curb plate, and tilt support board's lower extreme is connected on the cavity diapire and tilt support board's lower extreme is equipped with a gap, and tilt support board is in the same direction slope setting of supersonic velocity air current propagation in the sprue, and tilt support board's upper end is even as an organic whole with the one end of top curb plate, and the extending direction of top curb plate is put unanimously with the direction of supersonic velocity air current propagation in the sprue.

8. An ignition device in a supersonic cavity combustion chamber as defined in claim 7, wherein: the inner included angle between the inclined supporting plate and the top side plate is 120-150 degrees.

9. An ignition device in a supersonic cavity combustion chamber as defined in claim 8, wherein: the length of the gap is 80% -95% of the width of the guide plate, and the height of the gap is 1 mm-5 mm.

10. A scramjet engine comprising a supersonic combustion chamber, characterized in that an ignition device in the supersonic cavity combustion chamber as claimed in claim 1 is provided in the supersonic combustion chamber.

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