Ignition-enhanced ramjet combustion chamber and working method thereof

Abstract

The invention belongs to the technical field of ramjet engines, and discloses an ignition-enhanced ramjet engine combustion chamber and a working method thereof. The ignition enhancement type ramjet combustion chamber comprises a combustion chamber front expansion section, an ignition flame stabilizing section and a combustion chamber rear expansion section which are sequentially connected from front to back in the incoming flow direction, and center cavities of all the sections are through front and back. An annular flame stabilizing groove is formed in the inner wall face of the ignition flame stabilizing section, second-stage amplification grooves are evenly distributed in the circumferential direction of the flame stabilizing groove, first-stage amplification grooves are formed in the second-stage amplification grooves, and an igniter connector is formed in the top end of each first-stage amplification groove. According to the working method, the characteristic that the combustible mixed gas in each stage of backflow area formed by each stage of grooves flows stably is utilized, the combustible mixed gas is decelerated step by step, the combustible mixed gas with the low speed is obtained, then the igniter is used for ignition, the ignition reliability is improved, and the flame stability is enhanced; and the ignition Mach number range of various types of igniters on the ramjet engine is expanded.

Description

Technical Field

[0001] The present invention belongs to the technical field of ramjet engines, and particularly relates to an ignition-enhanced ramjet engine combustion chamber and its working method. Background Art

[0002] A ramjet engine consists of an inlet, an isolator, a combustion chamber, and a nozzle. The combustion chamber, as a device for generating high-temperature combustion gases in a ramjet engine, is an important component of the ramjet engine. The combustion chamber ignites the combustible mixture flowing in from the isolator to form high-temperature combustion gases that flow towards the nozzle. With the development of ramjet engines, the Mach number range used continues to widen, resulting in an increased Mach number variation range of the combustible mixture in the combustion chamber and an increased ignition difficulty. There may be a problem that it is difficult to ignite the combustion chamber even when multiple igniters work simultaneously.

[0003] Currently, there is an urgent need to develop an ignition-enhanced ramjet engine combustion chamber and its working method. Summary of the Invention

[0004] The present invention uses externally input energy for stable ignition at low Mach speeds. One technical problem to be solved is to provide an ignition-enhanced ramjet engine combustion chamber, and another technical problem to be solved is to provide a working method for the ignition-enhanced ramjet engine combustion chamber.

[0005] The ignition-enhanced ramjet engine combustion chamber of the present invention includes a front combustion chamber expansion section, an ignition and flame stabilization section, and a rear combustion chamber expansion section that are sequentially connected from front to back along the flow direction. The central cavities of each section are connected through from front to back, and the total length is L; The front combustion chamber expansion section is a conical tube, and its inner diameter gradually increases along the flow direction. The inner diameter at the inlet of the front combustion chamber expansion section is D1, and the angle between the conical generatrix of the front combustion chamber expansion section and the central axis is α; The ignition and flame stabilization section is a circular tube. The inner wall surface of the ignition and flame stabilization section is an annular flame stabilization groove. The inner diameter of the flame stabilization groove is D, the width is W1, and the depth is H1; A number of square protrusions are evenly distributed along the circumferential direction of the ignition and flame stabilization section. The outer wall surface of each square protrusion is an arc surface, and the inner wall surface is an arc groove. The arc groove forms a secondary amplification groove. The width of the secondary amplification groove is W2, W2 < W1, and the depth is H2; A radial circular tube is respectively arranged at the center of each square protrusion. The inner cavity of the radial circular tube forms a primary amplification groove. The inner diameter of the primary amplification groove is W3, W3 < W2, and the depth is H3; The top of the primary amplification groove is an igniter interface; The rear combustion chamber expansion section is also a conical tube, and its inner diameter gradually increases along the flow direction. The inner diameter at the outlet of the rear combustion chamber expansion section is D2, and the angle between the conical generatrix of the rear combustion chamber expansion section and the central axis is also α; D1 < D2 < D; A stepped transition is adopted between the front expansion section and the ignition and flame stabilization section of the combustion chamber, and a conical tube transition is adopted between the ignition and flame stabilization section and the rear expansion section of the combustion chamber; The parameters also satisfy the following relational expressions: 。

[0006] Furthermore, the range of the included angle α is 0.5° to 2°.

[0007] Furthermore, an igniter is installed on the igniter interface.

[0008] The working method of the combustion chamber of the ignition-enhanced ramjet engine of the present invention includes the following contents: a. Design the included angle between the conical generatrix and the central axis of the front expansion section of the combustion chamber, and the included angle between the conical generatrix and the central axis of the rear expansion section of the combustion chamber, reduce the influence of the inner wall boundary layer, and avoid the axial reduction of the main flow channel; b. Design flame stabilization grooves, secondary amplification grooves and primary amplification grooves in the ignition and flame stabilization section to form a stepped gas recirculation zone along the radial direction, gradually reduce the flow velocity of the combustible mixture gas, increase the temperature of the combustible mixture gas, use the gas recirculation zone in the ignition and flame stabilization section as the ignition zone of the combustion chamber of the ignition-enhanced ramjet engine, and improve the ignition success rate of the combustible mixture gas in the flame stabilization grooves; c. Connect the front end of the front expansion section of the combustion chamber to the tail end of the isolation section of the ramjet engine. The front expansion section of the combustion chamber is used to receive the combustible mixture gas formed by the mixture of fuel and air in the isolation section of the ramjet engine; d. Ignite the combustible mixture gas in the ignition and flame stabilization section, convert the combustible mixture gas into combustion gas and stably combust; the specific steps are as follows: d1. The combustible mixture gas enters the ignition and flame stabilization section from the front expansion section of the combustion chamber. Part of the combustible mixture gas forms a primary recirculation zone in the flame stabilization grooves. The flow velocity of the combustible mixture gas in the primary recirculation zone decreases and the temperature increases; the combustible mixture gas in the primary recirculation zone flows along the inner wall of the flame stabilization grooves to the secondary amplification grooves to form a secondary recirculation zone. The flow velocity of the combustible mixture gas in the secondary recirculation zone decreases step by step compared with that in the primary recirculation zone, and the temperature continues to increase; the combustible mixture gas in the secondary recirculation zone flows along the inner wall of the secondary amplification grooves to the primary amplification grooves to form a tertiary recirculation zone. The flow velocity of the combustible mixture gas in the tertiary recirculation zone continues to decrease step by step compared with that in the secondary recirculation zone, and the temperature continues to increase; d2. The igniter ignites, lighting the combustible mixture gas in the primary amplification groove. Combustion gas is formed in the tertiary recirculation zone. The combustion gas serves as an ignition source to ignite the combustible mixture gas in the secondary amplification groove, causing the combustible mixture gas in the secondary recirculation zone to be ignited and continue to form combustion gas. The combustion gas in the secondary amplification groove is used to ignite the combustible mixture gas in the flame stabilization groove. The combustion gas surrounds the flame stabilization groove, forming a ring-shaped distribution of combustion gas in the inner cavity of the flame stabilization groove and continuously burning stably, achieving the ignition of the combustible mixture gas in the ignition and flame stabilization section and completing the ignition process of the combustion chamber of the ignition-enhanced ramjet engine. e. In the inner cavity of the rear expansion section of the combustion chamber, the combustible mixture gas is further burned to improve the combustion efficiency of the combustible mixture gas, and the combustion gas is discharged into the ramjet engine nozzle for work conversion.

[0009] The combustion chamber of the ignition-enhanced ramjet engine and its working method of the present invention utilize the characteristic that the flow of the combustible mixture gas in the recirculation zones formed by each stage of grooves is relatively stable, gradually decelerate the combustible mixture gas, and obtain the combustible mixture gas with a lower speed, which is convenient for the igniter to ignite, solving the problem that the energy input by the external igniter is too small to directly ignite the combustible mixture gas in the combustion chamber. At the same time, the combustion gas continuously exchanges energy and working medium with the combustible mixture gas in each stage of amplification grooves, realizing stable flame combustion.

[0010] In short, the combustion chamber of the ignition-enhanced ramjet engine and its working method of the present invention use a small external input energy to stably ignite the combustible mixture gas at a low Mach number, which not only improves the ignition reliability but also enhances the flame stabilization ability, expands the ignition Mach number range of various types of igniters on the ramjet engine, and has engineering practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1a is a schematic structural diagram of the combustion chamber of the ignition-enhanced ramjet engine of the present invention; Figure 1b is a schematic structural diagram of the combustion chamber of the ignition-enhanced ramjet engine of the present invention ( Figure 1a sectional view taken along line B-B); Figure 2 is a schematic diagram of the design parameters of the combustion chamber of the ignition-enhanced ramjet engine of the present invention ( Figure 1a sectional view taken along line A-A).

[0012] In the figure, 101. Front expansion section of the combustion chamber; 201. Ignition and flame stabilization section; 202. Primary amplification groove; 203. Secondary amplification groove; 204. Flame stabilization groove; 205. Igniter interface; 301. Rear expansion section of the combustion chamber. DETAILED DESCRIPTION OF THE INVENTION

[0013] The embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand the other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0014] Embodiment: As Figure 1a 、 Figure 1b 、 Figure 2 shown, the combustion chamber of the ignition-enhanced ramjet engine in this embodiment includes a front expansion section 101, an ignition and flame stabilization section 201, and a rear expansion section 301 of the combustion chamber that are sequentially connected from front to back along the oncoming flow direction. The central cavities of each section are continuously connected from front to back, and the total length is L; The front expansion section 101 of the combustion chamber is a conical tube, and the inner diameter gradually increases along the oncoming flow direction. The inner diameter at the inlet of the front expansion section 101 of the combustion chamber is D1, and the angle between the conical generatrix of the front expansion section 101 of the combustion chamber and the central axis is α; The ignition and flame stabilization section 201 is a circular tube. The inner wall surface of the ignition and flame stabilization section 201 is an annular flame stabilization groove 204. The inner diameter of the flame stabilization groove 204 is D, the width is W1, and the depth is H1; A number of square protrusions are evenly distributed along the circumferential direction of the ignition and flame stabilization section 201. The outer wall surface of each square protrusion is an arc surface, and the inner wall surface is an arc groove. The arc groove forms a secondary amplification groove 203. The width of the secondary amplification groove 203 is W2, W2 < W1, and the depth is H2; A radial circular tube is respectively arranged at the center of each square protrusion. The inner cavity of the radial circular tube forms a primary amplification groove 202. The inner diameter of the primary amplification groove 202 is W3, W3 < W2, and the depth is H3; The top of the primary amplification groove 202 is an igniter interface 205; The rear expansion section 301 of the combustion chamber is also a conical tube, and the inner diameter gradually increases along the oncoming flow direction. The inner diameter at the outlet of the rear expansion section 301 of the combustion chamber is D2, and the angle between the conical generatrix of the rear expansion section 301 of the combustion chamber and the central axis is also α; D1 < D2 < D; A step transition is adopted between the front expansion section 101 of the combustion chamber and the ignition and flame stabilization section 201, and a conical tube transition is adopted between the ignition and flame stabilization section 201 and the rear expansion section 301 of the combustion chamber; Each parameter also satisfies the following relational expressions: .

[0015] Furthermore, the range of the angle α is 0.5° to 2°.

[0016] Furthermore, an igniter is installed on the igniter interface 205.

[0017] The working method of the combustion chamber of the ignition-enhanced ramjet engine in this embodiment includes the following content: a. Design the included angle between the conical generatrix and the central axis of the front expansion section 101 of the combustion chamber, and the included angle between the conical generatrix and the central axis of the rear expansion section 301 of the combustion chamber to reduce the influence of the inner wall boundary layer and avoid the axial reduction of the main flow path; b. Design flame stabilization grooves 204, secondary amplification grooves 203, and primary amplification grooves 202 in the ignition and flame stabilization section 201 to form a stepped gas recirculation zone along the radial direction, gradually reducing the flow velocity of the combustible mixture gas, increasing the temperature of the combustible mixture gas, using the gas recirculation zone in the ignition and flame stabilization section 201 as the ignition zone of the combustion chamber of the ignition-enhanced ramjet engine, and improving the ignition success rate of the combustible mixture gas in the flame stabilization grooves 204; c. Connect the front end of the front expansion section 101 of the combustion chamber to the tail end of the isolation section of the ramjet engine. The front expansion section 101 of the combustion chamber is used to receive the combustible mixture gas formed by the mixture of fuel and air in the isolation section of the ramjet engine; d. Ignite the combustible mixture gas in the ignition and flame stabilization section 201, convert the combustible mixture gas into combustion gas and stably burn. The specific steps are as follows: d1. The combustible mixture gas enters the ignition and flame stabilization section 201 from the front expansion section 101 of the combustion chamber. Part of the combustible mixture gas forms a primary recirculation zone in the flame stabilization grooves 204. The flow velocity of the combustible mixture gas in the primary recirculation zone decreases and the temperature increases. The combustible mixture gas in the primary recirculation zone flows along the inner wall of the flame stabilization grooves 204 to the secondary amplification grooves 203 to form a secondary recirculation zone. The flow velocity of the combustible mixture gas in the secondary recirculation zone decreases step by step compared with that in the primary recirculation zone, and the temperature continues to increase. The combustible mixture gas in the secondary recirculation zone flows along the inner wall of the secondary amplification grooves 203 to the primary amplification grooves 202 to form a tertiary recirculation zone. The flow velocity of the combustible mixture gas in the tertiary recirculation zone continues to decrease step by step compared with that in the secondary recirculation zone, and the temperature continues to increase; d2. The igniter ignites, igniting the combustible mixture gas in the primary amplification grooves 202, forming combustion gas in the tertiary recirculation zone. The combustion gas is used as an ignition source to ignite the secondary amplification grooves 203, so that the combustible mixture gas in the secondary recirculation zone is ignited to continue to form combustion gas; using the combustion gas in the secondary amplification grooves 203 to ignite the combustible mixture gas in the flame stabilization grooves 204, the combustion gas surrounds the flame stabilization grooves 204, forming a ring-shaped distribution of combustion gas in the inner cavity of the flame stabilization grooves 204 and continuously stably burning, realizing the ignition of the combustible mixture gas in the ignition and flame stabilization section 201 and completing the ignition process of the combustion chamber of the ignition-enhanced ramjet engine; e. In the inner cavity of the rear expansion section 301 of the combustion chamber, the combustible gas mixture is further combusted to improve the combustion efficiency of the combustible gas mixture, and the combustion gas is discharged into the ramjet nozzle for work conversion.

[0018] The above embodiments are only illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. An ignition-enhanced ramjet combustor, characterized in that, The described ignition-enhanced ramjet combustor includes a front expansion section (101), an ignition and flame stabilization section (201), and a rear expansion section (301) of the combustor that are sequentially connected from front to back along the oncoming flow direction. The central cavities of each section are connected through from front to back, and the total length is L. The front expansion section (101) of the combustor is a conical tube, and the inner diameter gradually increases along the oncoming flow direction. The inner diameter at the entrance of the front expansion section (101) of the combustor is D1, and the angle between the conical generatrix of the front expansion section (101) of the combustor and the central axis is α. The ignition and flame stabilization section (201) is a circular tube. The inner wall surface of the ignition and flame stabilization section (201) is an annular flame stabilization groove (204). The inner diameter of the flame stabilization groove (204) is D, the width is W1, and the depth is H1. Along the circumferential direction of the ignition and flame stabilization section (201), a number of evenly distributed square protrusions are provided. The outer wall surface of each square protrusion is an arc surface, and the inner wall surface is an arc groove. The arc grooves form a secondary amplification groove (203). The width of the secondary amplification groove (203) is W2, W2 < W1, and the depth is H2. Radial circular tubes are respectively arranged at the centers of each square protrusion. The inner cavities of the radial circular tubes form a primary amplification groove (202). The inner diameter of the primary amplification groove (202) is W3, W3 < W2, and the depth is H3. The top end of the primary amplification groove (202) is an igniter interface (205). The rear expansion section (301) of the combustor is also a conical tube, and the inner diameter gradually increases along the oncoming flow direction. The inner diameter at the exit of the rear expansion section (301) of the combustor is D2, and the angle between the conical generatrix of the rear expansion section (301) of the combustor and the central axis is also α. D1 < D2 < D. A step transition is adopted between the front expansion section (101) of the combustor and the ignition and flame stabilization section (201), and a conical tube transition is adopted between the ignition and flame stabilization section (201) and the rear expansion section (301) of the combustor. The following relationships are also satisfied by each parameter: 。 2. The combustion chamber of an ignition-enhanced ramjet engine according to claim 1, characterized in that, The range of the described angle α is 0.5° to 2°.

3. The combustion chamber of an ignition-enhanced ramjet engine according to claim 1, characterized in that, An igniter is installed on the described igniter interface (205).

4. A working method of an ignition-enhanced ramjet combustor, which is used for the ignition-enhanced ramjet combustor described in any one of claims 1 to 3, characterized in that, The described working method includes the following contents: a. Design the angles between the conical generatrices of the front expansion section (101) of the combustor and the central axis, and the angles between the conical generatrices of the rear expansion section (301) of the combustor and the central axis to reduce the influence of the boundary layer on the inner wall surface and avoid the axial reduction of the main flow channel. b. Design a flame stabilization groove (204), a secondary amplification groove (203), and a primary amplification groove (202) in the ignition and flame stabilization section (201) to form a stepped gas recirculation zone along the radial direction, gradually reduce the flow velocity of the combustible mixture, increase the temperature of the combustible mixture, and use the gas recirculation zone of the ignition and flame stabilization section (201) as the ignition zone of the ignition-enhanced ramjet combustor to improve the ignition success rate of the combustible mixture in the flame stabilization groove (204). c. Connect the front end of the front expansion section (101) of the combustor to the tail end of the isolation section of the ramjet. The front expansion section (101) of the combustor is used to receive the combustible mixture formed by the fuel and air mixture in the isolation section of the ramjet. d. Ignite the combustible mixture gas within the ignition and flame stabilization section (201), convert the combustible mixture gas into combustion gas and achieve stable combustion. The specific steps are as follows: d1. The combustible mixture gas enters the ignition and flame stabilization section (201) from the front expansion section (101) of the combustion chamber. Part of the combustible mixture gas forms a primary recirculation zone within the flame stabilization groove (204). The velocity of the combustible mixture gas within the primary recirculation zone decreases and the temperature increases. The combustible mixture gas in the primary recirculation zone flows along the inner wall of the flame stabilization groove (204) to the secondary amplification groove (203) to form a secondary recirculation zone. The flow velocity of the combustible mixture gas in the secondary recirculation zone decreases stepwise compared to that in the primary recirculation zone, and the temperature continues to rise. The combustible mixture gas in the secondary recirculation zone flows along the inner wall of the secondary amplification groove (203) to the primary amplification groove (202) to form a tertiary recirculation zone. The flow velocity of the combustible mixture gas in the tertiary recirculation zone continues to decrease stepwise compared to that in the secondary recirculation zone, and the temperature continues to rise. d2. The igniter ignites the combustible mixture gas within the primary amplification groove (202), and combustion gas is formed in the tertiary recirculation zone. The combustion gas serves as an ignition source to ignite the combustible mixture gas in the secondary amplification groove (203), causing the combustible mixture gas in the secondary recirculation zone to be ignited and continue to form combustion gas. The combustion gas in the secondary amplification groove (203) is used to ignite the combustible mixture gas in the flame stabilization groove (204). The combustion gas surrounds the flame stabilization groove (204), and a ring-shaped distribution of combustion gas is formed within the inner cavity of the flame stabilization groove (204) and continues to burn stably, achieving the ignition of the combustible mixture gas in the ignition and flame stabilization section (201) and completing the ignition process of the combustion chamber of the ignition-enhanced ramjet engine. e. In the inner cavity of the rear expansion section (301) of the combustion chamber, further burn the combustible mixture gas, improve the combustion efficiency of the combustible mixture gas, and discharge the combustion gas into the ramjet engine nozzle for work conversion.

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