Ignition-enhanced ramjet combustor and method of operation

Abstract

The application belongs to the technical field of ramjet engine, and discloses a kind of ignition enhanced ramjet engine combustion chamber and its working method.The ignition enhanced ramjet engine combustion chamber includes combustion chamber front expansion section, ignition flame stabilizing section and combustion chamber rear expansion section connected in sequence from front to back along the direction of incoming flow, and the center cavities of each section are through from front to back.The annular flame stabilizing groove is arranged on the inner wall of ignition flame stabilizing section, the circumferential direction of flame stabilizing groove is arranged with uniformly distributed secondary amplification groove, the primary amplification groove is arranged on the secondary amplification groove, and the top end of primary amplification groove is arranged with igniter interface.The working method uses the characteristics that the combustible mixture gas flow in each level of backflow area formed by each level of groove is relatively stable, gradually slows down the combustible mixture gas, obtains the combustible mixture gas with lower speed, and then ignites with igniter, which improves the ignition reliability and enhances the flame stability, and expands the ignition Mach number range of each type of igniter on the ramjet engine.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of ramjet engine, and particularly relates to a kind of ignition enhanced ramjet engine combustion chamber and its working method. BACKGROUND

[0002] Ramjet engine is composed of inlet, isolator, combustion chamber and nozzle, and the combustion chamber is an important component of ramjet engine as a device for generating high-temperature combustion gas. The combustion chamber ignites the combustible mixture flowing from the isolator to form a high-temperature combustion gas flow to the nozzle. With the development of ramjet engine, the use of Mach number is constantly widening, which leads to an increase in the range of Mach number of combustible mixture in the combustion chamber, making ignition more difficult. It may be difficult to ignite the combustion chamber even if multiple igniters are working at the same time.

[0003] Currently, it is urgent to develop an ignition enhanced ramjet engine combustion chamber and its working method. SUMMARY

[0004] The present application uses external input energy for stable ignition at low Mach number. One technical problem to be solved is to provide an ignition enhanced ramjet engine combustion chamber. 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 application comprises, in order from front to rear along the flow direction, a combustion chamber front expansion section, an ignition flame stabilization section and a combustion chamber rear expansion section. The center cavities of each section are through from front to rear, and the total length is L.

[0006] The combustion chamber front expansion section is a conical tube with an inner diameter gradually increasing along the flow direction. The inner diameter of the combustion chamber front expansion section at the inlet is D1, and the included angle between the conical generatrix of the combustion chamber front expansion section and the center axis is α.

[0007] The ignition flame stabilization section is a circular tube. The inner wall surface of the ignition flame stabilization section is an annular flame stabilization groove with an inner diameter D, a width W1 and a depth H1. The ignition flame stabilization section is provided with a plurality of square protrusions uniformly distributed along the circumferential direction. The outer wall surface of each square protrusion is a circular arc surface, and the inner wall surface is a circular arc groove. The circular arc groove forms a two-stage enlarged groove with a width W2 and a depth H2. W2 < W1. The center of each square protrusion is provided with a radial circular tube. The inner cavity of the radial circular tube forms a one-stage enlarged groove with an inner diameter W3 and a depth H3. W3 < W2. The top end of the one-stage enlarged groove is an igniter interface.

[0008] The combustion chamber rear expansion section is also a conical tube with an inner diameter gradually increasing along the flow direction. The inner diameter of the combustion chamber rear expansion section at the outlet is D2, and the included angle between the conical generatrix of the combustion chamber rear expansion section and the center axis is also α.

[0009] D1 < D2 < D; a step transition is adopted between the front expansion section of the combustion chamber and the ignition flame-holding section, and a conical tube transition is adopted between the ignition flame-holding section and the rear expansion section of the combustion chamber;

[0010] The parameters also satisfy the following relationships:

[0011] .

[0012] Further, the included angle a ranges from 0.5° to 2°.

[0013] Further, an igniter is mounted on the igniter interface.

[0014] The working method of the ignition-enhanced ramjet engine combustion chamber of the present application comprises the following contents:

[0015] a. The included angle between the conical generatrix of the front expansion section of the combustion chamber and the central axis, and the included angle between the conical generatrix of the rear expansion section of the combustion chamber and the central axis are designed to reduce the influence of the inner wall boundary layer and avoid the main flow passage from being reduced along the axial direction;

[0016] b. The flame-holding groove, the secondary amplification groove and the primary amplification groove are designed in the ignition flame-holding section to form a stepped gas backflow area along the radial direction, gradually reduce the flow rate of the combustible mixture gas, and increase the temperature of the combustible mixture gas. The gas backflow area of the ignition flame-holding section is used as the ignition area of the ignition-enhanced ramjet engine combustion chamber, and the ignition success rate of the combustible mixture gas in the flame-holding groove is improved;

[0017] c. The front end of the front expansion section of the combustion chamber is connected with the tail end of the ramjet engine isolation section, and the front expansion section of the combustion chamber is used for receiving the combustible mixture formed by mixing the fuel and air in the ramjet engine isolation section;

[0018] d. The combustible mixture is ignited in the ignition flame-holding section to convert the combustible mixture into combustion gas and stabilize combustion; the specific steps are as follows:

[0019] d1. The combustible mixture enters the ignition flame-holding section from the front expansion section of the combustion chamber, part of the combustible mixture forms a primary backflow area in the flame-holding groove, the flow rate of the combustible mixture in the primary backflow area is reduced, and the temperature is increased. The combustible mixture in the primary backflow area flows along the inner wall of the flame-holding groove to form a secondary backflow area in the secondary amplification groove, the flow rate of the combustible mixture in the secondary backflow area is further reduced, and the temperature continues to rise. The combustible mixture in the secondary backflow area flows along the inner wall of the secondary amplification groove to form a tertiary backflow area in the primary amplification groove, the flow rate of the combustible mixture in the tertiary backflow area is further reduced, and the temperature continues to rise;

[0020] d2. The igniter ignites the combustible mixture in the first-stage amplification groove, forming combustion gas in the third-stage recirculation zone. The combustion gas acts as an ignition source to ignite the second-stage amplification groove, causing the combustible mixture in the second-stage recirculation zone to be ignited and continue to form combustion gas. The combustion gas in the second-stage amplification groove is used to ignite the combustible mixture 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 continuing to burn stably. This achieves the ignition of the combustible mixture in the ignition-stabilized flame section, completing the ignition process of the combustion chamber of the ignition-enhanced ramjet engine.

[0021] e. In the rear expansion section of the combustion chamber, the combustible mixture is further burned to improve the combustion efficiency of the combustible mixture, and the combustion gas is discharged into the tail nozzle of the ramjet engine for power conversion.

[0022] The ignition-enhanced ramjet engine combustion chamber and its working method of the present invention utilize the relatively stable flow of combustible gas mixture in the recirculation zones formed by the grooves at each level to gradually decelerate the combustible gas mixture, resulting in a lower speed combustible gas mixture, which is convenient for ignition by the igniter. This solves the problem that the energy input from the external igniter is too small to directly ignite the combustible gas mixture in the combustion chamber. At the same time, the combustion gas continuously exchanges energy and working fluid with the combustible gas mixture in the enlarged grooves at each level, achieving stable flame combustion.

[0023] In summary, the ignition-enhanced ramjet engine combustion chamber and its operating method of the present invention utilize a small amount of external input energy to stably ignite combustible mixtures at low Mach speeds, thereby improving ignition reliability and enhancing flame stability. This expands the range of ignition Mach numbers for various types of igniters in ramjet engines and has practical engineering value. Attached Figure Description

[0024] Figure 1a This is a schematic diagram of the combustion chamber of the ignition-enhanced ramjet engine of the present invention;

[0025] Figure 1b This is a schematic diagram of the combustion chamber of the ignition-enhanced ramjet engine of the present invention. Figure 1a (BB cross-section view);

[0026] Figure 2 This is a schematic diagram of the design parameters for the combustion chamber of the ignition-enhanced ramjet engine of the present invention. Figure 1a (AA cross-section view).

[0027] In the diagram, 101 is the front expansion section of the combustion chamber; 201 is the ignition and flame stabilization section; 202 is the primary amplification groove; 203 is the secondary amplification groove; 204 is the flame stabilization groove; 205 is the igniter interface; and 301 is the rear expansion section of the combustion chamber. Detailed Implementation

[0028] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand 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.

[0029] Example: Figure 1a , Figure 1b , Figure 2 As shown, the combustion chamber of the ignition-enhanced ramjet engine in this embodiment includes a front expansion section 101, an ignition flame stabilization section 201, and a rear expansion section 301 connected sequentially from front to back along the flow direction. The central cavities of each section are connected from front to back, and the total length is L.

[0030] The combustion chamber front expansion section 101 is a conical tube with an inner diameter that gradually increases along the flow direction. The inner diameter at the inlet of the combustion chamber front expansion section 101 is D1, and the angle between the generatrix of the cone of the combustion chamber front expansion section 101 and the central axis is α.

[0031] The ignition and flame stabilization section 201 is a circular tube. The inner wall 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. The ignition and flame stabilization section 201 is provided with several square protrusions evenly distributed along the circumference. The outer wall of each square protrusion is an arc surface, and the inner wall 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. A radial circular tube is provided 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 the igniter interface 205.

[0032] The rear expansion section 301 of the combustion chamber is also a conical tube, with its inner diameter gradually increasing along the 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 generatrix of the cone of the rear expansion section 301 of the combustion chamber and the central axis is also α.

[0033] D1 < D2 < D; A stepped transition is used between the front expansion section 101 of the combustion chamber and the ignition and flame stabilization section 201, and a conical tube transition is used between the ignition and flame stabilization section 201 and the rear expansion section 301 of the combustion chamber.

[0034] The parameters also satisfy the following relationship:

[0035] .

[0036] Furthermore, the included angle α ranges from 0.5° to 2°.

[0037] Furthermore, an igniter is installed on the igniter interface 205.

[0038] The operating method of the combustion chamber of the ignition-enhanced ramjet engine in this embodiment includes the following:

[0039] a. Design the angle between the generatrix of the cone of the front expansion section 101 of the combustion chamber and the central axis, and the angle between the generatrix of the cone of the rear expansion section 301 of the combustion chamber and the central axis, to reduce the influence of the boundary layer on the inner wall surface and avoid axial reduction of the main flow channel;

[0040] b. A flame stabilizing groove 204, a secondary amplification groove 203, and a primary amplification groove 202 are designed within the ignition flame stabilizing section 201 to form a radially stepped gas recirculation zone, which gradually reduces the flow velocity of the combustible mixture and increases the temperature of the combustible mixture. The gas recirculation zone of the ignition flame stabilizing section 201 is used as the ignition zone of the combustion chamber of the ignition-enhanced ramjet engine, thereby improving the ignition success rate of the combustible mixture within the flame stabilizing groove 204.

[0041] c. Connect the front end of the combustion chamber front expansion section 101 to the rear end of the ramjet engine isolation section. The combustion chamber front expansion section 101 is used to receive the combustible mixture formed by the mixing of fuel and air in the ramjet engine isolation section.

[0042] d. Ignite the combustible mixture in the ignition and flame stabilization section 201, converting the combustible mixture into combustion gas and stabilizing combustion; the specific steps are as follows:

[0043] d1. The combustible gas mixture enters the ignition and flame stabilization section 201 from the front expansion section 101 of the combustion chamber. Part of the combustible gas mixture forms a primary recirculation zone in the flame stabilization groove 204. The velocity of the combustible gas mixture in the primary recirculation zone decreases and the temperature increases. The combustible gas mixture 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 velocity step of the combustible gas mixture in the secondary recirculation zone is smaller than that in the primary recirculation zone, and the temperature continues to rise. The combustible gas mixture 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 velocity step of the combustible gas mixture in the tertiary recirculation zone continues to decrease compared to that in the secondary recirculation zone, and the temperature continues to rise.

[0044] d2. The igniter ignites the combustible mixture in the first-stage amplification groove 202, forming combustion gas in the third-stage recirculation zone. The combustion gas serves as an ignition source to ignite the second-stage amplification groove 203, causing the combustible mixture in the second-stage recirculation zone to be ignited and continue to form combustion gas. The combustion gas in the second-stage amplification groove 203 is used to ignite the combustible mixture in the flame stabilization groove 204. The combustion gas surrounds the flame stabilization groove 204, forming a ring-shaped distribution of combustion gas in the inner cavity of the flame stabilization groove 204 and continuing to burn stably. This achieves the ignition of the combustible mixture in the ignition stabilization section 201, completing the ignition process of the ignition-enhanced ramjet engine combustion chamber.

[0045] e. In the rear expansion section 301 of the combustion chamber, the combustible mixture is further burned to improve the combustion efficiency of the combustible mixture, and the combustion gas is discharged into the tail nozzle of the ramjet engine for power conversion.

[0046] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A combustion chamber for an ignition-enhanced ramjet engine, characterized in that, The combustion chamber of the ignition-enhanced ramjet engine includes a front expansion section (101), an ignition flame stabilization section (201), and a rear expansion section (301) connected sequentially from front to back along the flow direction. The central cavities of each section are connected from front to back, and the total length is L. The combustion chamber front expansion section (101) is a conical tube with an inner diameter that gradually increases along the flow direction. The inner diameter at the inlet of the combustion chamber front expansion section (101) is D1, and the angle between the generatrix of the cone of the combustion chamber front expansion section (101) and the central axis is α. The ignition and flame stabilization section (201) is a circular tube. The inner wall 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. The ignition and flame stabilization section (201) is provided with several square protrusions evenly distributed along the circumference. The outer wall of each square protrusion is an arc surface, and the inner wall 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. The center of each square protrusion is provided with a radial circular tube. 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 the igniter interface (205). The rear expansion section (301) of the combustion chamber is also a conical tube, with its inner diameter gradually increasing along the 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 generatrix of the cone of the rear expansion section (301) of the combustion chamber and the central axis is also α. D1 < D2 < D; A stepped transition is used between the front expansion section (101) and the ignition and flame stabilization section (201) of the combustion chamber, and a conical tube transition is used between the ignition and flame stabilization section (201) and the rear expansion section (301) of the combustion chamber; The parameters also satisfy the following relationship: ； The combustion chamber of the ignition-enhanced ramjet engine utilizes the stable flow of the incoming combustible gas mixture in the recirculation zones formed by the grooves at each level to gradually decelerate the combustible gas mixture, resulting in a lower speed combustible gas mixture, which facilitates ignition in the ignition and flame stabilization section (201). At the same time, the combustion gas continuously exchanges energy and working fluid with the combustible gas mixture in the enlarged grooves at each level, achieving stable flame combustion.

2. The combustion chamber of an ignition-enhanced ramjet engine according to claim 1, characterized in that, The included angle α ranges from 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 igniter interface (205).

4. A method for operating a combustion chamber of an ignition-enhanced ramjet engine, used in any one of the ignition-enhanced ramjet engine combustion chambers described in claims 1 to 3, characterized in that, The working method includes the following: a. Design the angle between the generatrix of the cone of the front expansion section (101) of the combustion chamber and the central axis, and the angle between the generatrix of the cone of the rear expansion section (301) of the combustion chamber and the central axis, to reduce the influence of the boundary layer on the inner wall surface and avoid the main channel shrinking along the axis; b. A flame stabilization groove (204), a secondary amplification groove (203), and a primary amplification groove (202) are designed in the ignition flame stabilization section (201) to form a radially stepped gas recirculation zone, which gradually reduces the flow rate of the combustible mixture and increases the temperature of the combustible mixture. The gas recirculation zone of the ignition flame stabilization section (201) is used as the ignition zone of the combustion chamber of the ignition-enhanced ramjet engine, thereby improving the ignition success rate of the combustible mixture in the flame stabilization groove (204). c. Connect the front end of the combustion chamber front expansion section (101) to the rear end of the ramjet engine isolation section. The combustion chamber front expansion section (101) is used to receive the combustible mixture formed by the mixing of fuel and air in the ramjet engine isolation section. d. Ignite the combustible mixture in the ignition and flame stabilization section (201), converting the combustible mixture into combustion gas and stabilizing combustion; the specific steps are as follows: d1. The combustible gas mixture enters the ignition and flame stabilization section (201) from the front expansion section (101) of the combustion chamber. Part of the combustible gas mixture forms a primary recirculation zone in the flame stabilization groove (204). The velocity of the combustible gas mixture in the primary recirculation zone decreases and the temperature increases. The combustible gas mixture 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 velocity of the combustible gas mixture in the secondary recirculation zone decreases stepwise compared to that in the primary recirculation zone, and the temperature continues to rise. The combustible gas mixture 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 velocity of the combustible gas mixture in the tertiary recirculation zone continues to decrease stepwise compared to that in the secondary recirculation zone, and the temperature continues to rise. d2. Ignition by the igniter ignites the combustible mixture in the first-stage amplification groove (202), forming combustion gas in the third-stage recirculation zone. The combustion gas serves as an ignition source to ignite the second-stage amplification groove (203), causing the combustible mixture in the second-stage recirculation zone to be ignited and continue to form combustion gas. The combustion gas in the second-stage amplification groove (203) is used to ignite the combustible mixture in the flame stabilization groove (204). The combustion gas surrounds the flame stabilization groove (204), forming a ring-shaped distribution of combustion gas in the inner cavity of the flame stabilization groove (204) and continuing to burn stably. This achieves the ignition of the combustible mixture in the ignition stabilization section (201) and completes 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 mixture is further burned to improve the combustion efficiency of the combustible mixture, and the combustion gas is discharged into the tail nozzle of the ramjet engine for power conversion.

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