CN112984554B

CN112984554B - High-speed premixing jet flow flame combustion enhancing device based on gas ejector

Info

Publication number: CN112984554B
Application number: CN202110233951.3A
Authority: CN
Inventors: 王泰宇; 王振国; 孙明波; 蔡尊; 李佩波
Original assignee: National University of Defense Technology
Current assignee: National University of Defense Technology
Priority date: 2021-03-03
Filing date: 2021-03-03
Publication date: 2022-04-05
Anticipated expiration: 2041-03-03
Also published as: CN112984554A

Abstract

The invention discloses a high-speed premixing jet flow flame combustion enhancing device based on a gas ejector, which comprises a shell, wherein a contraction cavity, a first equal-straight cavity, an expansion cavity and a second equal-straight cavity are sequentially communicated and arranged in the shell. This flame combustion reinforcing means utilizes the gas of high-speed efflux flame to draw the external air of injection effect to force to be drawn and penetrate the air current and mix with the high-speed gas of center, thereby can improve the combustion efficiency in efflux flame zone, realize the burning reinforcing in the high-speed efflux flame total flow section, and can accomplish the exothermic focus of efflux burning through the space restriction effect. Meanwhile, due to the gas injection effect, the combustion enhancer can achieve self-adaptive cooling and can work around high-temperature jet flame for a long time.

Description

High-speed premixing jet flow flame combustion enhancing device based on gas ejector

Technical Field

The invention relates to the technical field of flame combustion enhancement, in particular to a high-speed premixing jet flow flame combustion enhancement device based on a gas ejector.

Background

Based on the characteristic of high speed, especially the characteristic of high self speed of supersonic premixed gas jet, the residence time of the gas in a limited high-temperature section is very short, which causes part of the fuel to be separated from a flame core area before the fuel does not participate in the reaction, thereby causing the waste of the fuel. In addition, in the middle and rear part of the supersonic flame, the internal pressure of the flame rises due to the combustion reaction, so that part of the un-ignited gas is extruded out of the central flame area, part of the fuel cannot normally participate in the combustion reaction all the time, and the overall combustion efficiency is also reduced. Meanwhile, the flame structure of the central jet main body starts to be transversely dispersed at the middle rear part, and the top focusing of flame heat cannot be realized.

In the prior art, a flame tracing furnace is usually adopted to generate high-speed jet flame and properly enhance the combustion efficiency of the jet flame, for the structure of the existing flame tracing furnace, a central jet hole is arranged in the center of a furnace disc of the flame tracing furnace and used for jetting cold premixed gas with different speeds, and a large-area flame tracing plane is arranged on the periphery of the furnace disc and used for generating low-speed flame tracing. The prior flame-following furnace can generate supersonic flame with the speed as high as Ma1.6 (central jet flow outlet) and can keep the flame stable for combustion. Fig. 1 is a typical transient grayscale photograph of the operation of a flame burner, in which fig. 1(a) shows that only the flame burner plate is operated and ignited, and fig. 1(b) shows that the central high mach number (central jet exit ma1.2) jet is ejected and spontaneously burns under the flame envelope.

As can be seen from figure 1, because the central jet flow speed is high, the flame accompanied by combustion is rapidly sucked close to the central jet flow flame body under the injection action, so that the flame accompanied by combustion does not wrap the middle upper part of the flame of the jet flow body, and the high-speed flame is directly exposed in the external cold air to bring adverse effects to the combustion of the flame. Furthermore, in such high velocity jet flames, it is also seen that the flame structure is spontaneously enlarged due to the high pressure zone generated by combustion inside the flame, which is presumed to cause the external unburned gas to be discharged out of the flame, also resulting in low combustion efficiency.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides the high-speed premixed jet flame combustion enhancing device based on the gas ejector, which not only can realize combustion enhancement in the full flow section of the high-speed premixed jet flame, but also can realize top heat release focusing of the jet flame.

In order to achieve the purpose, the invention provides a high-speed premixing jet flow flame combustion enhancing device based on a gas ejector, which comprises a shell, wherein the shell is internally provided with:

the two ends of the contraction cavity are provided with a first inlet and a first outlet, and the cross-sectional area of the contraction cavity is gradually reduced along the direction from the first inlet to the first outlet;

a second inlet and a second outlet are arranged at two ends of the first equal straight cavity, the cross sections of the first equal straight cavity along the direction from the second inlet to the second outlet are the same, the second inlet is connected with the first outlet, and the shape of the second inlet is the same as that of the first outlet;

the expansion cavity is provided with a third inlet and a third outlet at two ends, the cross-sectional area of the expansion cavity is gradually increased along the direction from the third inlet to the third outlet, the third inlet is connected with the second outlet, and the third inlet and the second outlet are in the same shape;

a fourth inlet and a fourth outlet are arranged at two ends of the second equal-straight cavity, the cross sections of the second equal-straight cavity along the direction from the fourth inlet to the fourth outlet are the same, the fourth inlet is connected with the third outlet, and the shape of the fourth inlet is the same as that of the third outlet;

the first inlet is located at one end of the housing and the fourth outlet is located at the other end of the housing.

In one embodiment, the housing comprises four bases corresponding to the contraction cavity, the first equal straight cavity, the expansion cavity and the second equal straight cavity;

the contraction cavity, the first equal-straight cavity, the expansion cavity and the second equal-straight cavity are respectively arranged in the corresponding basal bodies and penetrate through the corresponding basal bodies:

and the substrates are sequentially detachably and fixedly connected.

In one embodiment, each of the substrates is provided with a through cavity penetrating through the substrate, and the wall of the through cavity is provided with a detachable profile unit for enclosing the contraction cavity, the first equal-straight cavity, the expansion cavity or the second equal-straight cavity.

In one embodiment, adjacent substrates are fixedly connected through bolts.

In one embodiment, the matching surfaces between the adjacent substrates are provided with concave-convex inserting structures.

In one embodiment, the mating surfaces between adjacent substrates are provided with sealing structures.

In one embodiment, the sealing structure is a sealing rubber ring.

In one embodiment, the housing further includes a cover body, and the cover body is sleeved on the combined structure formed by the bases.

According to the high-speed premixing jet flow flame combustion enhancing device based on the gas ejector, the external air is sucked by utilizing the gas ejection effect of the high-speed jet flow flame, and the ejected air flow is forced to be mixed with the central high-speed gas, so that the combustion efficiency of a jet flow flame area can be improved, the combustion enhancement is realized in the full flow section of the high-speed jet flow premixing flame, and the focusing of jet flow combustion heat release can be completed through the space limiting effect. Meanwhile, due to the gas injection effect, the combustion enhancer can achieve self-adaptive cooling and can work around high-temperature jet flame for a long time.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is a schematic transient view of a typical operation of a prior art flame-following furnace;

FIG. 2 is an isometric view of a first embodiment of a flame combustion enhancement device in an example embodiment of the invention;

FIG. 3 is a cross-sectional view of a first embodiment of a flame combustion enhancement device in an example of the invention;

FIG. 4 is a schematic illustration of a flame combustion enhancement apparatus in accordance with an embodiment of the invention during a particular application;

FIG. 5 is a schematic diagram of the mechanism of action of the flame combustion enhancing apparatus of an embodiment of the present invention;

FIG. 6 is a cross-sectional view of a second embodiment of a flame combustion enhancement device in an example of the invention;

FIG. 7 is a schematic view of a connection structure between the profile unit and the base according to an embodiment of the present invention;

FIG. 8 is a schematic view showing a connection structure between substrates in the embodiment of the present invention;

FIG. 9 is an enlarged schematic view of a portion A identified in FIG. 8;

FIG. 10 is a cross-sectional view of a third embodiment of a flame combustion enhancement device in accordance with an example embodiment of the invention;

FIG. 11 is an enlarged schematic view of a portion B shown in FIG. 10;

FIG. 12 is a schematic structural diagram of an experimental system in an embodiment of the present invention;

FIG. 13 is a schematic diagram of the definition of H in an experiment in an example of the present invention;

FIG. 14 is a plot of OH spontaneous emission contours at different H conditions for experiments in examples of the invention;

fig. 15 is a CH4 mass fraction coloring flow chart of a three-dimensional numerical simulation in an embodiment of the present invention.

The reference numbers illustrate: the device comprises a shell 1, a base body 101, a profile unit 102, bolts 103, a sunken groove 104, an annular protrusion 105, an annular groove 106, a sealing groove 107, a sealing rubber ring 108, a cover body 109, a contraction cavity 201, a first equal straight cavity 202, an expansion cavity 203, a second equal straight cavity 204, a fixing support 3, a high-speed premixed jet flame 4, a premixed combustion furnace 5, outside air 6, an ICCD camera 7, an electric lifting platform 8 and an optical platform 9.

The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.

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

In the present invention, unless otherwise expressly stated or limited, the terms "connected," "secured," and the like are to be construed broadly, and for example, "secured" may be a fixed connection, a removable connection, or an integral part; the connection can be mechanical connection, electrical connection, physical connection or wireless communication connection; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In addition, the technical solutions in the embodiments of the present invention may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination of technical solutions should not be considered to exist, and is not within the protection scope of the present invention.

Fig. 2 to 3 show a high-speed premix jet flame 4 combustion enhancing device (hereinafter referred to as "flame combustion enhancing device") based on a gas ejector disclosed in this embodiment, which includes a housing 1, and a contraction cavity 201, a first equal-straight cavity 202, an expansion cavity 203, and a second equal-straight cavity 204 are sequentially disposed in the housing 1. A first inlet and a first outlet are arranged at two ends of the contraction cavity 201, and the cross-sectional area of the contraction cavity 201 is gradually reduced along the direction from the first inlet to the first outlet; a second inlet and a second outlet are arranged at two ends of the first equal straight cavity 202, the cross sections of the first equal straight cavity 202 along the direction from the second inlet to the second outlet are the same, the second inlet is connected with the first outlet, and the shape of the second inlet is the same as that of the first outlet; a third inlet and a third outlet are arranged at two ends of the expansion cavity 203, the cross-sectional area of the expansion cavity 203 is gradually increased along the direction from the third inlet to the third outlet, the third inlet is connected with the second outlet, and the shape of the third inlet is the same as that of the second outlet; a second equal-straight cavity 204, wherein a fourth inlet and a fourth outlet are arranged at two ends of the second equal-straight cavity 204, the cross section of the second equal-straight cavity 204 along the direction from the fourth inlet to the fourth outlet is the same, the fourth inlet is connected with the third outlet, and the shape of the fourth inlet is the same as that of the third outlet; the first inlet is located at one end of the housing 1, and the fourth outlet is located at the other end of the housing 1, that is, the contraction cavity 201, the first equal straight cavity 202, the expansion cavity 203 and the second equal straight cavity 204 are connected in sequence to form a straight line channel penetrating through the housing 1.

Referring to fig. 4, the flame combustion enhancement device in this embodiment is suspended by a fixed bracket 3 directly above the high-speed premixed jet flame 4 and kept at a proper distance from the jet exit plane of the premixed burner 5 during the specific application process. Referring to fig. 5, the mechanism of action of the flame combustion enhancing means is:

because the high-speed premix efflux flame 4 draws the suction effect, outside air 6 can be inhaled in the flame burning reinforcing means, the external air 6 of subsonic speed can be compressed to shrink chamber 201, then with high-speed premix efflux flame 4 in first equal straight chamber 202 carry out the compulsory mixing for the central efflux of flame is because strong shearing effect fully slows down in first equal straight chamber 202, back via expanding chamber 203, the gas mixture speed reduction pressure boost after the mixing, combustion reaction is further promoted. Meanwhile, the outer injected air is tightly attached to the inner wall of the flame combustion enhancement device to protect the flame combustion enhancement device from being directly eroded by flame, and in addition, the higher the intensity of the high-speed premixed jet flame 4 (the larger the flow), the more the injected air amount (before the air inlet is blocked), and the dynamic relation actually forms self-adaptive thermal protection on the combustion enhancement device. Therefore, the flame combustion enhancement device in the embodiment can not only realize combustion enhancement in the full flow section of the high-speed jet premixed flame, but also realize the top heat release focusing of the high-speed premixed jet flame 4.

Fig. 2 to 3 are only the first embodiment of the flame combustion enhancement device in the present embodiment, and the housing 1, the contraction cavity 201, the first equal straight cavity 202, the expansion cavity 203 and the second equal straight cavity 204 in the embodiment are integrally formed. It should be noted that although the flame combustion enhancing means is illustrated as having a rectangular cross-sectional configuration, in particular applications, the flame combustion enhancing means may be provided as having a circular cross-section or other non-uniform cross-sectional configuration.

Referring to fig. 6, a second embodiment of the flame combustion enhancement device in the present embodiment is shown, in which the lower casing 1 includes four bases 101 corresponding to a contraction cavity 201, a first equal straight cavity 202, an expansion cavity 203, and a second equal straight cavity 204; the contraction cavity 201, the first equal-straight cavity 202, the expansion cavity 203 and the second equal-straight cavity 204 are respectively arranged in the corresponding base body 101 and penetrate through the corresponding base body 101, and the base bodies 101 are sequentially detachably and fixedly connected through a connecting structure.

In this embodiment, each substrate 101 is provided with a through cavity penetrating through itself, and the wall of the through cavity is provided with a detachable profile unit 102 for enclosing a contraction cavity 201, a first equal-straight cavity 202, an expansion cavity 203, or a second equal-straight cavity 204. In the implementation process, the profile unit 102 may be a separate unit with a cylindrical structure, or may be an assembly of two units oppositely disposed on the inner wall of the base 101. Taking a flame combustion enhancement device with a rectangular cross section as an example, the profile unit 102 on each base 101 in this example comprises two unit pieces which are symmetrically connected to two inner walls of the base 101, and the two inner profile units 102 and the other two side walls of the base 101 jointly enclose a contraction cavity 201, a first equal straight cavity 202, an expansion cavity 203 or a second equal straight cavity 204. The surface of the unit element contacting with the base 101 is a plane, the surface of the unit element facing to the contraction cavity 201, the first equal straight cavity 202, the expansion cavity 203 or the second equal straight cavity 204 is designed according to requirements, and therefore, when the shape and the size of each cavity in the flame combustion enhancement device are adjusted, only the unit element needs to be replaced.

Referring to fig. 7, in the present embodiment, a snap-fit connection with a T-shaped groove structure is formed between the profile unit 102 and the base 101, specifically, a portion of the profile unit 102 connected to the base 101 is configured as a T-shaped protrusion structure with a T-shaped cross section, and a corresponding T-shaped groove is formed on the base 101, and then, a detachable fixed connection between each profile unit 102 and the base 101 is realized through an embedded cooperation of the T-shaped protrusion structure and the T-shaped groove. Of course, it is also possible to provide T-grooves on the profile unit 102 and T-projections on the base 101.

Referring to fig. 8, in the present embodiment, adjacent substrates 101 are fixedly connected to each other by bolts 103. Specifically, a plurality of heavy grooves 104 are circumferentially arranged on the side wall close to the top end and the side wall close to the bottom end, and the adjacent base bodies 101 are detachably and fixedly connected through the cooperation of the heavy grooves 104 and the bolts 103.

Preferably, the matching surfaces between the adjacent substrates 101 are provided with concave-convex plug-in structures. Specifically, in two adjacent base bodies 101, an annular protrusion 105 is arranged on a corresponding end face of one of the base bodies 101, the annular protrusion 105 surrounds an end portion of a through cavity on the base body 101, an annular groove 106 corresponding to the annular protrusion 105 is arranged on a corresponding end face of the other base body 101, when the two base bodies 101 are connected, the annular protrusion 105 is embedded into the corresponding annular groove 106 to form a concave-convex insertion structure, and therefore the air tightness of the connection between the two adjacent base bodies 101 is improved.

Further preferably, the number of the annular protrusions 105 and the number of the annular recesses are two, the corresponding end face of one substrate 101 is provided with one annular protrusion 105 and one annular recess 106, the corresponding end face of the other substrate 101 is provided with the other annular protrusion 105 and the other annular recess 106, and therefore the matching surface between the adjacent substrates 101 is provided with two concave-convex inserting structures, and the inserting directions of the two concave-convex inserting structures are opposite to each other, so that the air tightness of connection between the two adjacent substrates 101 is further improved.

Referring to fig. 9, in the present embodiment, the mating surfaces between the adjacent bases 101 are each provided with a sealing structure, which is a sealing groove 107 provided on the mating surface between the two bases 101 and a sealing rubber ring 108 provided in the sealing groove 107. In a preferred embodiment, the sealing rubber ring 108 is arranged between the two concave-convex plugging structures.

Referring to fig. 10 to 11, a third embodiment of the flame combustion enhancement device in this embodiment is that the lower housing 1 of this embodiment further includes a cover 109, and the cover 109 is sleeved on the combined structure formed by the substrates 101, so that the cover 109 can cover the connecting gap between the substrates 101, improve the air tightness of the flame combustion enhancement device, and can play a certain role in fixing the connected substrates 101.

The flame combustion enhancing device in the present embodiment is further verified and explained below by combining specific experiments and three-dimensional numerical calculations.

As shown in fig. 12, the experimental site includes an ICCD camera 7, a methane-air premixing combustion furnace, a fixing bracket 3, an electric lift platform 8, and a flame combustion enhancing device, and for convenience of observation, the flame combustion enhancing device in the experiment is made of glass, and there is no curved surface in the view field direction of the ICCD camera 7. The flame combustion enhancing device is arranged on the electric lifting platform 8 through the fixed support 3, the methane-air premixing combustion furnace is arranged on the electric lifting platform, and the flame combustion enhancing device is suspended in the air through the fixed support 3 and is arranged right above the high-speed premixing jet flame 4 of the methane-air premixing combustion furnace. An ICCD camera 7 is placed on the optical platform 9 for imaging the flame burning enhancement device with the high velocity premixed jet flame 4. The ICCD camera 7 is equipped with an ultraviolet lens and a narrow-band filter of 310nm for photographing OH^*Spontaneous emission. A methane-air premixed combustion burner is used to generate a high-speed premixed jet flame 4 with an exit velocity of 300 m/s.

In the experiment, the positions of the flame combustion enhancement device and the ICCD camera 7 are not changed, and the electric lifting platform 8 is operated to control the lifting of the methane-air premixed combustion furnace, so that the purpose of controlling the size of H in the graph 13 is achieved. The combustion conditions of the high-speed premixed jet flame 4 without the combustion enhancer effect were compared simultaneously in the experiment. The experimental results can be seen in fig. 14 (in fig. 14, the dotted line at the lower part is the center line of the furnace plate, the dotted line at the upper part is the ignition point connecting line of the high-speed premixed jet flame 4, and the image at the rightmost side is the high-speed premixed jet flame 4 without the action of the flame combustion enhancing device), it can be easily observed that OH distribution strength is greatly different under different H conditions, and when H is 4cm and 4.5cm, the flame strength is obviously stronger than that of the high-speed premixed jet flame 4 without the action of the flame combustion enhancing device. The flame combustion enhancing device can play a good combustion-supporting role after the proper action distance is selected.

In addition, three-dimensional numerical simulation is carried out, and a typical result is shown in fig. 15, a flow chart shows that air around the flame combustion enhancement device is drawn, and meanwhile, the air drawn into the enhancer is rapidly mixed and reacted with methane in the tube (as can be seen from the consumption speed of methane in the flame combustion enhancement device in fig. 15), and an adherent protective layer is formed, so that the flame combustion enhancement device can be greatly protected from high temperature. The numerical simulation result proves that the flame combustion enhancing device can achieve the effect of forced mixing and combustion of the fuel and the oxidant in the forced high-speed premixed jet flame 4 by injecting surrounding air, and can form self-adaptive thermal protection for the flame combustion enhancing device.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. The utility model provides a high-speed premix efflux flame combustion reinforcing means based on gas ejector which characterized in that, includes the casing, be equipped with in the casing:

2. The gas injector-based high-speed premix jet flame combustion enhancement device of claim 1, wherein the housing comprises four bases corresponding to the converging cavity, the first equal straight cavity, the diverging cavity, and the second equal straight cavity, respectively;

and the substrates are sequentially detachably and fixedly connected.

3. The high-speed premixed jet flame combustion enhancing device based on the gas ejector as claimed in claim 2, wherein each substrate is provided with a through cavity penetrating through the substrate, and the wall of the through cavity is provided with a detachable profile unit for enclosing the contraction cavity or the first equal-straight cavity or the expansion cavity or the second equal-straight cavity.

4. The high-speed premixing jet flow flame combustion enhancing device based on the gas ejector is characterized in that adjacent base bodies are fixedly connected through bolts.

5. The high-speed premixing jet flow flame combustion enhancing device based on the gas ejector as claimed in claim 2 or 3, wherein concave-convex inserting structures are arranged on matching surfaces between adjacent substrates.

6. The high-speed premixed jet flame combustion enhancing device based on the gas ejector as claimed in claim 2 or 3, wherein a sealing structure is arranged on a matching surface between adjacent substrates.

7. The gas injector-based high-speed premix jet flame combustion enhancement device of claim 6, wherein the sealing structure is a sealing rubber ring.

8. The high-speed premixed jet flame combustion enhancing device based on the gas ejector as claimed in claim 2 or 3, wherein the housing further comprises a cover body, and the cover body is sleeved on a combined structure formed by the bases.