A stable flame structure of a strut-plate rocket coupled with a cavity

Abstract

The application discloses a stable flame structure of a strut plate rocket and a cavity coupling, which comprises a ramjet flow channel, an annular cavity, at least one strut plate fixedly connected with the inner wall surface of the ramjet flow channel, and at least one rocket fixedly connected with the strut plate and equal in number to the strut plate. The cavity body of the cavity is in the shape of a right-angled trapezoid along the cross section of the axial symmetry surface of the ramjet flow channel, and the side of the right-angled trapezoid close to the air inlet is a right-angled waist, and the cavity can form a cavity backflow area. The rocket is fixedly connected with the bottom surface of the strut plate, the end of the top surface of the strut plate along the air flow direction abuts against the cavity, and the rear end surface of the strut plate is inclined towards the cavity, so that the flow loss of the air flow is reduced. The front edge wall surface of the cavity and the two side wall surfaces of the strut plate are provided with a plurality of kerosene injection holes with the injection direction being perpendicular to the axis of the ramjet flow channel. The strut plate, the rocket and the cavity are coupled, so that the flame in the ramjet is stable and efficiently combusted under the condition of low incoming air total temperature.

Description

Technical Field

[0001] This invention relates to the field of flame stabilization technology for RBCC engines, and in particular to a flame stabilization structure that couples a support plate rocket with a concave cavity. Background Technology

[0002] Rocket-Based Combined Cycle (RBCC) engines combine the advantages of high specific impulse of ramjet engines and high thrust-to-weight ratio of rocket engines, improving the performance of aerospace propulsion systems and representing an important future direction for aerospace propulsion.

[0003] However, the flow combustion process in the combustion chamber of the RBCC engine is extremely complex. The incoming air velocity in the RBCC engine is relatively high, and the fuel residence time in the combustion chamber is relatively short. The fuel injection and mixing, ignition, flame propagation and flame stabilization in the combustion chamber need to be completed within an effective time, which makes it difficult to organize combustion and stabilize the flame in the combustion chamber of the RBCC engine. Summary of the Invention

[0004] Based on this, it is necessary to provide a flame stabilization structure that couples the support plate rocket with the concave cavity to address the above-mentioned technical problems. Through the coupling effect of the support plate, rocket and concave cavity, stable and efficient combustion of the flame inside the ramjet engine under low total incoming flow temperature conditions is achieved.

[0005] This invention provides a flame stabilization structure for a rocket with a support plate coupled to a concave cavity, comprising:

[0006] The ramjet combustion chamber flow channel is a frustum-shaped shell, with the end with the smaller radial cross-sectional area serving as the incoming air inlet.

[0007] An annular cavity is located in the middle of the ramjet combustion chamber flow channel and is integrally connected with the ramjet combustion chamber sub-flow channel. The axis of the cavity coincides with the axis of the ramjet combustion chamber flow channel, and the cavity protrudes from the inside to the outside relative to the wall of the ramjet combustion chamber flow channel.

[0008] At least one support plate is provided in the direction of airflow, the support plate is located upstream of the cavity, and the support plate is fixedly connected to the inner wall surface of the flow channel of the ram-fired combustion chamber.

[0009] At least one rocket, the number of rockets being equal to the number of support plates, the rockets being fixedly connected to the support plates, and the axis of the rockets being parallel to the axis of the ramjet combustion chamber flow channel;

[0010] The cross-sectional shape of the cavity along the axial symmetry plane of the ramjet combustion chamber flow channel is a right trapezoid. The side of the right trapezoid closest to the incoming air inlet is the right leg, which is perpendicular to the axis of the ramjet combustion chamber flow channel.

[0011] The side of the support plate closest to the cavity is defined as the rear end face of the support plate. The rocket is fixedly connected to the bottom surface of the support plate, and the top surface of the support plate is fixedly connected to the inner wall surface of the ramjet combustion chamber flow channel. The end of the top surface of the support plate along the airflow direction abuts against the cavity. The rear end face of the support plate is inclined to the cavity so that the rocket's outlet is located in the flow channel where the cavity is located.

[0012] The side of the cavity closest to the incoming air inlet is defined as the front edge of the cavity. The front edge wall of the cavity and the two side walls of the support plate are provided with multiple kerosene injection holes with the injection direction perpendicular to the axis of the flow channel of the ram-fired combustion chamber.

[0013] In one embodiment, there are two rockets, the axes of which are symmetrical about the axis of the ramjet combustion chamber flow channel, and the distance between the axes of the two rockets is 0.09m to 0.11m.

[0014] In one embodiment, the ratio of the length of the lower base to the length of the right leg of the trapezoid is 4 to 7, and the angle between the lower base and the non-right leg of the trapezoid is 30° to 60°.

[0015] In one embodiment, the support plate is wedge-shaped and includes an integrally connected compression section and a parallel section. The included angle between the two compression surfaces of the compression section is 13° to 17°. The end of the compression section near the incoming air inlet is the top end. The top end of the compression section is rounded. The bottom end of the compression section is connected to the parallel section.

[0016] The symmetry line of the top surface of the support plate is parallel to the axis of the ramjet combustion chamber flow channel, and the rear end of the support plate is inclined at an angle of 50° to 70° towards the concave cavity.

[0017] In one embodiment, the rocket is a gas-oxygen-kerosene rocket, and the rocket's exit section is parallel to the front end face of the cavity.

[0018] In one embodiment, the number of kerosene injection holes on the front edge wall of the cavity is 15 to 25, and the kerosene injection holes on the front edge wall of the cavity are distributed in an equidistant array along the axial circumference on the front edge wall of the cavity.

[0019] In one embodiment, the support plate is a hollow cavity, and multiple kerosene injection holes are provided on both side walls of the support plate, with 8 to 12 kerosene injection holes provided on the side wall of each support plate.

[0020] The beneficial effects of this invention are:

[0021] (1) The present invention sets up an oxygen-kerosene rocket inside the flow channel of the ramjet combustion chamber to carry out fuel-rich combustion and generate a fuel-rich high-temperature jet. The high-temperature jet contains a large number of high-temperature free radicals and combustible gas. After the jet enters the flow channel of the ramjet combustion chamber, it mixes with the incoming fresh air and undergoes secondary combustion, thereby making the overall combustion and heat release of the engine more complete.

[0022] (2) This invention creates a concave cavity with a right-angled trapezoidal cross-section along the axial symmetry plane of the ramjet combustion chamber flow channel, and a support plate inclined at its rear end towards the concave cavity, forming a support plate tail recirculation zone and a concave cavity recirculation zone within the ramjet combustion chamber flow channel. Kerosene injected into the sidewall of the support plate initially mixes with the incoming air and is then entrained into the support plate tail recirculation zone and the concave cavity recirculation zone through a vortex effect, where it mixes and combusts with the incoming air and high-temperature jet. Kerosene injected into the leading edge wall of the concave cavity further mixes and combusts with the incoming air and high-temperature jet entering the concave cavity recirculation zone. The coupling of the two recirculation zones enhances mixing while shortening reaction time and ignition delay, thereby improving combustion efficiency and resulting in better flame stabilization performance.

[0023] (3) The backflow zone of the support plate uses the vortex effect to couple the gas backflow in the cavity with the high-temperature jet of the rocket, forming a larger and more stable coupled flame stabilization zone, which improves the stability of the flame in the ramjet engine. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the flame stabilization structure of the support plate rocket and the concave cavity provided in an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the support plate provided in an embodiment of the present invention;

[0026] Figure 3 This is a three-dimensional spatial distribution diagram of the high-temperature combustion zone formed by the coupled flame stabilization structure of the support plate rocket and the concave cavity of the present invention.

[0027] Figure 4 This is a plan view of the high-temperature combustion zone formed by the support plate rocket and the concave cavity coupled flame stabilization structure of the present invention.

[0028] Figure 5 This is a streamline distribution diagram showing the coupling effect between the support plate rocket and the concave cavity flame stabilization structure of the present invention.

[0029] Explanation of reference numerals in the attached drawings: 1. Flow channel of the rammed combustion chamber; 2. Rocket; 3. Support plate; 4. Cavity; 5. Compression section; 6. Parallel section; 7. Kerosene injection hole. Detailed Implementation

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0031] It should be noted that in the description of this invention, "upper," "lower," "top," "bottom," and orientation or positional relationship are based on the appendix. Figure 1The orientations or positional relationships shown are for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

[0032] In one embodiment, such as Figure 1 As shown, Figure 1 This is a schematic diagram of the flame stabilization structure of the rocket with a support plate coupled to the cavity provided in this embodiment of the invention. The flame stabilization structure of the rocket with a support plate coupled to the cavity in this embodiment includes:

[0033] The ramjet combustion chamber flow channel 1 is a frustum-shaped shell with the end having the smaller radial cross-sectional area as the incoming air inlet.

[0034] Specifically, the ramjet combustion chamber flow channel 1, which has a frustum-shaped shell, has an expansion angle of 4°, and can generate positive thrust with a slightly expanded shape.

[0035] An annular cavity 4 is located in the middle of the ramjet combustion chamber flow channel 1 and is integrally connected with the ramjet combustion chamber sub-flow channel. The axis of the cavity 4 coincides with the axis of the ramjet combustion chamber flow channel 1, and the cavity 4 protrudes from the inside to the outside relative to the wall surface of the ramjet combustion chamber flow channel 1.

[0036] At least one support plate 3 is disposed upstream of the cavity 4 along the airflow direction, and the support plate 3 is fixedly connected to the inner wall surface of the ram-fired combustion chamber channel 1.

[0037] At least one rocket 2, the number of rocket 2 is equal to the number of support plates 3, the rocket 2 is fixedly connected to the support plate 3, and the axis of the rocket 2 is parallel to the axis of the ramjet combustion chamber flow channel 1.

[0038] It should be noted that the number of rockets 2 is preferably 1 to 6. In this embodiment, the number of rockets 2 is specifically two. The axes of the two rockets 2 are symmetrical about the axis of the ramjet combustion chamber flow channel 1, and the distance between the axes of the two rockets 2 is 0.09m to 0.11m. In this embodiment, it is specifically 0.1m.

[0039] In this embodiment, the exit section of rocket 2 is parallel to the front end face of cavity 4. Rocket 2 is a gas oxygen kerosene rocket that operates in a low-flow, fuel-rich state, generating a fuel-rich, high-temperature jet. The high-temperature jet contains a large number of high-temperature free radicals and combustible gases. After the jet enters the ramjet combustion chamber flow channel 1, it mixes with the incoming fresh air and undergoes secondary combustion, thereby making the overall combustion and heat release of the engine more complete.

[0040] The cross-sectional shape of the cavity 4 along the axial symmetry plane of the ramjet combustion chamber flow channel 1 is a right trapezoid. The side of the right trapezoid closest to the incoming air inlet is the right leg, which is perpendicular to the axis of the ramjet combustion chamber flow channel 1.

[0041] In this right trapezoid, the ratio of the lower base to the right leg is 4–7, and the angle between the lower base and the non-right leg is 30°–60°. In this embodiment, the ratio is specifically 5, and the angle is specifically 45°.

[0042] The side of the support plate 3 closest to the cavity 4 is defined as the rear end face of the support plate 3. The rocket 2 is fixedly connected to the bottom surface of the support plate 3. The top surface of the support plate 3 is fixedly connected to the inner wall surface of the ramjet combustion chamber flow channel 1. The end of the top surface of the support plate 3 along the airflow direction abuts against the cavity 4. The rear end face of the support plate 3 is inclined to the cavity 4 so that the outlet of the rocket 2 is located in the flow channel where the cavity 4 is located.

[0043] It should be noted that the top surface of the support plate 3 abuts against the cavity 4 at its end along the airflow direction, that is, the rightmost side of the top surface of the support plate 3 abuts against the front edge wall of the cavity 4. The rear end of the support plate 3 is inclined towards the cavity 4 to reduce airflow loss.

[0044] The side of the cavity 4 closest to the incoming air inlet is defined as the front edge of the cavity 4. The front edge wall of the cavity 4 and the two side walls of the support plate 3 are provided with multiple kerosene injection holes 7 with the injection direction perpendicular to the axis of the ram-fired combustion chamber channel 1.

[0045] The airflow separates after passing through the leading edge wall of the cavity 4, creating a low-speed recirculation zone inside the cavity 4, which prolongs the residence time of the gas. In this embodiment, the diameter of the kerosene injection hole 7 is 0.3 mm.

[0046] It should be noted that the kerosene injection hole 7 is connected to the kerosene supply pipeline, which in turn is connected to the fuel supply agent oxidation system. The kerosene injection hole 7 is used to inject secondary kerosene. The kerosene injected from the side wall of the support plate 3 initially mixes with the incoming air and is then entrained into the recirculation zone at the tail of the support plate 3 and the recirculation zone of the concave cavity 4 through a vortex effect. There, it mixes and burns with the incoming air and the high-temperature jet. The kerosene injected from the leading edge wall of the concave cavity 4 further mixes and burns with the incoming air and the high-temperature jet entering the recirculation zone of the concave cavity 4. This coupling of combustion in the two recirculation zones enhances mixing while shortening the reaction time and ignition delay, thereby improving combustion efficiency and resulting in better flame stabilization performance.

[0047] In one embodiment, such as Figure 2 As shown, Figure 2This is a schematic diagram of the support plate 3 provided in an embodiment of the present invention. The support plate 3 is wedge-shaped and includes an integrally connected compression section 5 and a parallel section 6. The included angle between the two compression surfaces of the compression section 5 is 13° to 17°. The end of the compression section 5 closest to the incoming air inlet is the top end, which is rounded. The bottom end of the compression section 5 is connected to the parallel section 6. The symmetry line of the top surface of the support plate 3 is parallel to the axis of the ramjet combustion chamber flow channel 1, and the rear end of the support plate 3 is inclined at an angle of 50° to 70° towards the concave cavity 4. In this embodiment, the support plate 3 can form a vortex effect at the tail end, allowing the fuel-rich, high-temperature rocket jet combustion gas to be entrained into the tail end of the support plate 3 and the recirculation zone inside the concave cavity 4 through the vortex structure, thus achieving the mixing and combustion of the rocket jet 2 with fresh incoming air and secondary kerosene.

[0048] Specifically, the rear end of the support plate 3 is inclined at an angle of 60° towards the cavity 4.

[0049] In one embodiment, the number of kerosene injection holes 7 on the leading edge wall of the cavity 4 is 15 to 25, and the kerosene injection holes 7 on the leading edge wall of the cavity 4 are distributed in an equidistant array along the axial circumference. The support plate 3 is a hollow cavity, and multiple kerosene injection holes 7 are provided on both side walls of the support plate 3, with 8 to 12 kerosene injection holes 7 on each side wall of the support plate 3.

[0050] Specifically, in this embodiment, the number of kerosene injection holes 7 on the front edge wall of the cavity 4 is 20, and 10 kerosene injection holes 7 are provided on the side wall of each support plate 3. The 10 kerosene injection holes 7 on the side wall of each support plate 3 are evenly arranged on the side wall of the support plate 3 along the inclined direction of the rear end face of the support plate 3.

[0051] The kerosene injection holes 7 on the front edge wall of the cavity 4 are distributed in an axial circumferential equidistant array on the front edge wall of the cavity 4, and 10 kerosene injection holes 7 are set on the side wall of each support plate 3 and are evenly arranged along the inclined direction of the rear end face of the support plate 3, which can realize the uniform injection of kerosene.

[0052] In one specific embodiment, the RBCC engine was flown according to the operating parameters in Table 1 to simulate and verify the flame stabilization effect and combustion effect of the flame stabilization structure coupled with the cavity of the present invention.

[0053] Table 1 Numerical Simulation Operating Conditions

[0054]

[0055] The RBCC engine operates at Mach 2.0, an altitude of 8 km, a flight pressure of 100 kPa, and an incoming total air temperature of 424 K. At this altitude, the engine inlet captures an airflow of 5.8 kg / s. The operating conditions of Rocket 2 are shown in Table 2. Rocket 2 combustion chambers employ gas-oxygen-kerosene combustion with an oxygen-fuel ratio of 1.0. The flow rate of a single Rocket 2 is 60 g / s, operating at a low flow rate. At this low flow rate, the total temperature of the Rocket 2 combustion chamber is 1786 K, and the total pressure is close to 1 MPa. The exit composition of Rocket 22 is 0.93913 CO, 0.00115 CO2, 0.05808 H2, and 0.00164 H2O.

[0056] Table 2 Rocket Operating Conditions

[0057]

[0058] The simulation results are analyzed by Figure 3 and Figure 4 As can be seen, the flame in the combustion zone is stable in this embodiment, and combustion mainly occurs in the coupled recirculation zone at the tail of the support plate 3 and in the cavity 4, as well as in the combustion chamber flow channel downstream of the rocket 2. The high-speed airflow entering the combustion chamber mixes with the secondary kerosene injected into the side wall of the support plate 3, and then, through the vortex effect, is drawn into the recirculation zone at the tail of the support plate 3. Under the action of shear force, it forms a reactive mixing layer with the high-temperature gas jet from the rocket 2. Within this reactive mixing layer, the kerosene and air undergo intense mixing and chemical reactions with the high-temperature gas jet from the rocket 2. The recirculation zone formed at the tail of the support plate 3 utilizes the vortex effect to draw the kerosene, air, and high-temperature gas jet from the rocket 2 into the recirculation zone of the cavity 4, forming a coupled flame-stabilizing zone. Secondary kerosene is injected into the leading edge wall of the cavity 4, further mixing with the high-speed incoming flow and high-temperature gas jet drawn into the recirculation zone of the cavity 4 through the vortex structure, resulting in intense combustion and the release of a large amount of heat. The coupled flame stabilization zone enhances the residence time of kerosene fuel in the combustion chamber while reducing the chemical reaction time of the kerosene fuel. This makes the chemical reaction timescale in the combustion chamber smaller than the flow timescale, achieving continuous flame stability in the coupled flame stabilization zone and allowing the flame to propagate downstream of the ramjet combustion chamber flow channel 1 into a continuous flame. Figure 5 It can be seen that when the incoming air passes through the coupled flame stabilization zone, it is entrained into the tail of the support plate 3 and the recirculation zone inside the cavity 4, where it is violently mixed with the high-temperature combustion gas of rocket 2, secondary kerosene fuel, and the high-temperature combustion gas in the recirculation zone, and then propagates downstream. Figure 3 , Figure 4 and Figure 5 Analysis shows that the flame stabilization structure of the support plate rocket and the concave cavity in this embodiment can achieve a larger coverage area of ​​the coupled flame stabilization zone and effectively stabilize the flame.

[0059] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A stable flame structure of a strut-plate rocket coupled with a cavity, characterized in that, include: The ramjet combustion chamber flow channel (1) is a frustum-shaped shell with the end having a smaller radial cross-sectional area as the inlet for incoming air. An annular cavity (4) is provided in the middle of the ramjet combustion chamber flow channel (1) and is integrally connected with the ramjet combustion chamber flow channel (1). The axis of the cavity (4) coincides with the axis of the ramjet combustion chamber flow channel (1). The cavity (4) protrudes from the inside to the outside relative to the wall surface of the ramjet combustion chamber flow channel (1). At least one support plate (3) is provided upstream of the cavity (4) along the air flow direction, and the support plate (3) is fixedly connected to the inner wall surface of the ram-fired combustion chamber flow channel (1); At least one rocket (2), the number of which is equal to the number of support plates (3), the rocket (2) is fixedly connected to the support plate (3), and the axis of the rocket (2) is parallel to the axis of the ramjet combustion chamber flow channel (1); The cavity (4) has a right trapezoidal cross-sectional shape along the axial symmetry plane of the ramjet combustion chamber flow channel (1). The side of the right trapezoid closest to the incoming air inlet is a right-angled waist, which is perpendicular to the axis of the ramjet combustion chamber flow channel (1). The side of the support plate (3) near the cavity (4) is defined as the rear end face of the support plate (3). The rocket (2) is fixedly connected to the bottom surface of the support plate (3). The top surface of the support plate (3) is fixedly connected to the inner wall surface of the ramjet combustion chamber flow channel (1). The end of the top surface of the support plate (3) along the air flow direction abuts against the cavity (4). The rear end face of the support plate (3) is inclined to the cavity (4) so ​​that the outlet of the rocket (2) is located in the flow channel where the cavity (4) is located. The side of the cavity (4) closest to the incoming air inlet is defined as the front edge of the cavity (4). The front edge wall of the cavity (4) and the two side walls of the support plate (3) are provided with a plurality of kerosene injection holes (7) with the injection direction perpendicular to the axis of the ram-fired combustion chamber flow channel (1). The support plate (3) is wedge-shaped and includes an integrally connected compression section (5) and parallel section (6). The included angle between the two compression surfaces of the compression section (5) is 13°~17°. The end of the compression section (5) near the incoming air inlet is the top. The top of the compression section (5) is rounded. The bottom of the compression section (5) is connected to the parallel section (6). The symmetry line of the top surface of the support plate (3) is parallel to the axis of the ram-fired combustion chamber channel (1), and the rear end of the support plate (3) is inclined at an angle of 50°~70° towards the concave cavity (4).

2. The structure of a flameholder-rocket and cavity coupling according to claim 1, characterized in that, The number of rockets (2) is two, and the axes of the two rockets (2) are symmetrical about the axis of the ramjet combustion chamber channel (1). The distance between the axes of the two rockets (2) is 0.09m~0.11m.

3. A flame stabilizing structure for coupling a support plate rocket with a concave cavity as described in claim 1 or 2, characterized in that, The ratio of the length of the lower base to the length of the right leg of the right trapezoid is 4 to 7, and the angle between the lower base and the non-right leg of the right trapezoid is 30° to 60°.

4. The flame stabilizing structure of a support plate rocket coupled with a concave cavity as described in claim 3, characterized in that, The rocket (2) is a gas oxygen kerosene rocket, and the exit section of the rocket (2) is parallel to the front end face of the cavity (4).

5. The flame stabilizing structure of a support plate rocket coupled with a concave cavity as described in claim 4, characterized in that, The number of kerosene injection holes (7) on the front edge wall of the cavity (4) is 15 to 25, and the kerosene injection holes (7) on the front edge wall of the cavity (4) are distributed in an equidistant array along the axial circumference on the front edge wall of the cavity (4).

6. The flame stabilizing structure of a support plate rocket coupled with a concave cavity as described in claim 5, characterized in that, The support plate (3) is a hollow cavity. Both side walls of the support plate (3) are provided with multiple kerosene injection holes (7). Each side wall of the support plate (3) is provided with 8 to 12 kerosene injection holes (7).

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