Device and method for realizing efficient extraction of graded detonation energy

Abstract

The invention discloses a device and a method for realizing efficient extraction of graded detonation energy, and the method creatively changes the existing pulse detonation technology, and adopts two-stage detonation on the premise of not changing the initial filling pressure instead of adopting single detonation; the method specifically comprises the steps that initial detonation waves are formed at low filling pressure in two straight-pipe-shaped detonation combustion chambers through first-stage detonation, and overfilled fuel is pre-compressed; in the second-stage detonation, direct detonation is conducted through shock wave focusing at high filling pressure in an expansion cavity, the pressure of a combustion device is improved through two-stage detonation combustion, efficient extraction of fuel chemical energy is achieved, and the thermodynamic cycle performance of a power system adopting the combustion mode is improved; and meanwhile, the problem of fuel waste caused by over-filling is solved, and the structure is simpler and more efficient.

Description

Technical Field

[0001] This invention belongs to the field of combustion device technology for power systems, and relates to the design technology of detonation combustion chambers and pulse detonation engines, and particularly to a device and method for achieving efficient extraction of staged detonation energy. Background Technology

[0002] Detonation combustion is a supersonic combustion process. During detonation combustion, a strong shock wave coupled with the chemical reaction surface exists, propagating at supersonic speeds relative to the unburned premixed gas, reaching speeds of up to 2000 m / s. The combustion products following the detonation wave do not have enough time to expand, resulting in increased density behind the detonation wave. Therefore, detonation combustion has the advantage of self-pressurization. Power plants based on detonation combustion have thermodynamic cycles close to isochoric combustion, but with higher pressure gain. Compared to traditional engines using isobaric combustion, engines using detonation combustion have higher specific impulse, lower fuel consumption, a more compact structure, and can operate over a wider envelope, making them a promising next-generation power plant for the aerospace field.

[0003] Common pulse detonation engines operate in an intermittent mode, with the process consisting of four stages: reactant loading, ignition, detonation wave initiation, and exhaust. These four stages are repeated cyclically, with operating frequencies reaching tens or even hundreds of hertz. Among the key technologies of detonation engines, the loading and initiation of the combustible mixture (the detonation wave generation process) is one of the most challenging and crucial aspects.

[0004] To achieve higher detonation pressure and greater engine performance, the initial filling pressure must be increased to allow the detonation wave to ignite in a higher filling pressure environment. However, this places higher demands on the supply system, making it more complex and increasing the weight and size of the entire power system. The advantages of detonation combustion due to its self-pressurization are no longer apparent. Currently, there are two methods for ignition initiation: direct ignition and slow combustion-to-detonation. Since direct initiation requires very high ignition energy, the latter is the commonly used method. However, to achieve the slow combustion-to-detonation process, obstacles need to be added inside the detonation tube to increase the flame propagation speed and promote the formation of the detonation wave. Detonation power plants using this ignition method are limited by size and weight, and can only organize one stage of detonation combustion; there is still room for improvement in energy extraction efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide an apparatus and method for efficient extraction of staged detonation energy, in order to improve the problem that the energy extraction efficiency of existing detonation combustion technology is not ideal.

[0006] To achieve the above objectives, the present invention employs the following technical solution: A device for efficient extraction of staged detonation energy includes a first straight-tube detonation combustion chamber, a second straight-tube detonation combustion chamber, and an expansion chamber, wherein: The front portions of the inner cavities of the first and second straight-tube detonation combustion chambers are respectively equipped with a first helical structure and a second helical structure; the dimensions of the first and second straight-tube detonation combustion chambers are the same; the front end of the expansion cavity is an ellipsoidal end, and the remaining portion is a straight pipe section; the rear ends of the first and second straight-tube detonation combustion chambers are symmetrically connected to the ellipsoidal ends of the expansion cavity, and the angle between their axes and the axis of the expansion cavity is the same.

[0007] Furthermore, the angle between the axis of the first straight-tube detonation combustion chamber and the axis of the expansion chamber is in the range of 30° to 60°; the ratio of the diameter D3 of the straight section of the expansion chamber to the diameter D1 of the first straight-tube detonation combustion chamber, D3 / D1, is in the range of 5 to 10.

[0008] Furthermore, the first and second straight-tube detonation combustion chambers serve as the sites of the first-stage detonation, and their lengths L1 and L2 and diameters D1 and D2 are completely identical. At the same time, their first and second helical structures are also completely identical.

[0009] Furthermore, ignition position C and ignition position D are respectively provided near the front end of the first straight-tube detonation combustion chamber and the second straight-tube detonation combustion chamber.

[0010] Furthermore, parameter acquisition units, including ion probes and pressure sensors, are installed in the first straight-tube detonation combustion chamber, the second straight-tube detonation combustion chamber, and the expansion chamber. The ion probes are used to detect the flame reaction surface at their location to determine whether a detonation wave is generated. The pressure sensors are used to detect the pressure at their location.

[0011] A method for efficiently extracting energy from staged detonation includes: Step 1: Introduce a combustible mixture into the head A and B of the first straight-tube detonation combustion chamber and the second straight-tube detonation combustion chamber, and fill the first straight-tube detonation combustion chamber, the second straight-tube detonation combustion chamber and the expansion chamber with the combustible mixture; Step 2: Simultaneously ignite the combustible mixture at ignition positions C and D in the first and second straight-tube detonation combustion chambers. Step 3: After the ignited combustible mixture is accelerated by the turbulence of the first spiral structure and the second spiral structure, it forms the first-stage detonation wave, which propagates in the direction of the expansion cavity. Step 4: After the first-stage detonation wave propagates to the ellipsoidal end of the expansion cavity, the detonation wave decouples due to the sudden expansion of the diameter of the propagation channel, becoming a normal shock wave and a chemical reaction zone. The normal shock wave enters the expansion cavity first and compresses the unburned combustible mixture that has filled the expansion cavity. Step 5: The decoupled normal shock waves meet and collide at the center E of the ellipsoidal end of the expansion cavity, generating a new detonation hot spot through the shock wave focusing effect, igniting the compressed combustible mixture in the expansion cavity, and forming a second-stage detonation wave. Step 6: The second-stage detonation wave burns the compressed combustible mixture in the expansion chamber, and the combustion products are discharged backward through the straight section of the expansion chamber. Step 7: Repeat steps 1 to 6 to make the power system carrying the extraction device work in a cycle.

[0012] Furthermore, during the power system cycle, parameters in the first straight-tube detonation combustion chamber, the second straight-tube detonation combustion chamber, and the expansion chamber are simultaneously detected; when it is determined that a detonation wave is formed in the first straight-tube detonation combustion chamber, the second straight-tube detonation combustion chamber, and the expansion chamber, and the detonation pressure in the expansion chamber is higher than the detonation pressure in the first straight-tube detonation combustion chamber and the second straight-tube detonation combustion chamber, the two-stage detonation is successful.

[0013] Furthermore, the operating frequency of the two-stage detonation can be adjusted by changing the filling time of the combustible mixture and the ignition frequency of the active ignition.

[0014] Furthermore, the combustible mixture is a gas mixture formed by mixing combustible gas with air or oxygen at points A and B of the head; or: The combustible mixture is a two-phase fluid formed by mixing a combustible liquid with air or oxygen at points A and B in the head after atomization.

[0015] A power system equipped with the device and operating cyclically using the method.

[0016] A pulse detonation engine employing the aforementioned power system.

[0017] Compared with the prior art, the present invention has the following technical features: 1. This invention proposes a staged detonation energy extraction method. Without changing the initial filling pressure, the leading shock wave after the decoupling of the detonation wave is used to compress the combustible mixture in the expansion cavity, so that the secondary detonation can be carried out at a higher filling pressure, thereby improving the energy extraction efficiency.

[0018] 2. The combustible mixture filled into the straight-tube detonation combustion chamber undergoes a first-stage detonation, and the unburned combustible mixture continues to burn in the expansion chamber through a second-stage detonation, thus solving the fuel waste caused by overfilling.

[0019] 3. The secondary detonation in the expansion cavity of this invention is initiated by shock wave focusing, eliminating the need for a separate ignition device and the need for a slow combustion to detonation process, resulting in a simpler structure.

[0020] 4. Experimental verification shows that the method of the present invention can achieve two-stage detonation, thus broadening the types and working principles of detonation engines. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the combustion device in this invention.

[0022] Explanation of reference numerals in the attached drawings: 1-First straight-tube detonation combustion chamber, 2-Second straight-tube detonation combustion chamber, 3-Expansion chamber, 4-First helical structure, 5-Second helical structure, A-Head of the first straight-tube detonation combustion chamber, B-Head of the second straight-tube detonation combustion chamber, C-Ignition position of the first straight-tube detonation combustion chamber, D-Ignition position of the second straight-tube detonation combustion chamber, E-Center of the ellipsoidal end, α-Angle between the first straight-tube detonation combustion chamber and the expansion chamber, β-Angle between the second straight-tube detonation combustion chamber and the expansion chamber. Detailed Implementation

[0023] The method for achieving staged detonation in this invention represents a groundbreaking change from existing pulse detonation technology. Instead of a single detonation, it employs two-stage detonation without altering the initial filling pressure. This method efficiently extracts the chemical energy of the fuel through two-stage detonation combustion. Specifically, the first-stage detonation forms an initial detonation wave at a lower filling pressure in two straight-tube detonation combustion chambers, pre-compressing the overfilled fuel. The second-stage detonation is initiated directly in the expansion chamber at a higher filling pressure through shock wave focusing. This two-stage detonation combustion increases the pressure of the combustion device, achieving efficient extraction of the fuel's chemical energy and improving the thermodynamic cycle performance of the power system using this combustion method.

[0024] See Figure 1 This invention first proposes a device for efficient extraction of staged detonation energy, comprising a first straight-tube detonation combustion chamber 1, a second straight-tube detonation combustion chamber 2, and an expansion chamber 3, wherein: The front part of the inner cavity of the first straight-tube detonation combustion chamber 1 and the second straight-tube detonation combustion chamber 2 is respectively equipped with a first helical structure 4 and a second helical structure 5; the size of the first straight-tube detonation combustion chamber 1 and the second straight-tube detonation combustion chamber 2 are the same; the front end of the expansion cavity 3 is an ellipsoidal end, and the rest is a straight pipe section; the rear ends of the first straight-tube detonation combustion chamber 1 and the second straight-tube detonation combustion chamber 2 are symmetrically connected to the ellipsoidal end of the expansion cavity 3, and the included angles between them and the axis of the expansion cavity 3 are α and β, respectively; the values ​​of included angles α and β are in the range of 30°~60°.

[0025] In this design, the first straight-tube detonation combustion chamber 1 and the second straight-tube detonation combustion chamber 2 serve as the sites of the first-stage detonation. Their lengths L1 and L2 and diameters D1 and D2 are identical, as are the first helical structure 4 and the second helical structure 5, and their included angles α and β. This ensures that the first-stage detonation wave from the first straight-tube detonation combustion chamber 1 and the first-stage detonation wave from the second straight-tube detonation combustion chamber 2 simultaneously reach the center E of the ellipsoidal end, colliding to generate a detonation hotspot. The expansion cavity 3 serves as the site of the second-stage detonation; its front end is ellipsoidal, and the remainder is a straight tube.

[0026] In order to decouple the first-stage detonation wave within the expansion cavity 3, the detonation wave must undergo a geometric expansion process to ensure the diameter of the first straight-tube detonation combustion chamber 1 in the expansion cavity 3. Therefore, the ratio of the diameter D3 of the straight section of the expansion cavity 3 to the diameter D1 of the first straight-tube detonation combustion chamber 1, D3 / D1, is in the range of 5 to 10.

[0027] Ignition positions C and D are respectively provided near the front end of the first straight-tube detonation combustion chamber 1 and the second straight-tube detonation combustion chamber 2. In this embodiment, ignition positions C and D are located at the first helical structure 4 and the second helical structure 5. The first helical structure 4 and the second helical structure 5 are used to accelerate the transition from slow combustion to detonation, and promote the formation of a first-stage detonation wave in the first straight-tube detonation combustion chamber 1 and the second straight-tube detonation combustion chamber 2.

[0028] In this scheme, parameter acquisition units are set in the first straight-tube detonation combustion chamber 1, the second straight-tube detonation combustion chamber 2, and the expansion chamber 3 to detect the parameters at their respective locations. The parameter acquisition units include ion probes and pressure sensors. The ion probes are used to detect the flame reaction surface at their respective locations to determine whether a detonation wave is generated. The pressure sensors are used to detect the pressure at their respective locations.

[0029] Based on the above technical solutions, the present invention provides a method for efficient extraction of staged detonation energy, comprising the following steps: Step 1: A combustible mixture is introduced into the head A and B of the first straight-tube detonation combustion chamber 1 and the second straight-tube detonation combustion chamber 2, respectively, to fill the first straight-tube detonation combustion chamber 1, the second straight-tube detonation combustion chamber 2 and the expansion chamber 3.

[0030] The combustible mixture is a gas mixture formed by mixing combustible gas with air or oxygen at points A and B of the head.

[0031] Optionally, the combustible mixture may also be a two-phase fluid of gas and liquid formed by atomizing a combustible liquid and mixing it with air or oxygen at points A and B in the head.

[0032] Step 2: Simultaneously ignite the combustible mixture at ignition positions C and D of the first straight-tube detonation combustion chamber 1 and the second straight-tube detonation combustion chamber 2.

[0033] Step 3: After the ignited combustible mixture is accelerated by the turbulence of the first spiral structure 4 and the second spiral structure 5, it forms a first-stage detonation wave that propagates toward the expansion cavity 3.

[0034] Step 4: After the first-stage detonation wave propagates to the ellipsoidal end of the expansion cavity 3, the detonation wave decouples due to the sudden expansion of the diameter of the propagation channel, becoming a normal shock wave and a chemical reaction zone. The normal shock wave enters the expansion cavity first and compresses the combustible mixture that was filled into the expansion cavity 3 in step 1 but has not yet burned.

[0035] Step 5: The decoupled normal shock waves meet and collide at the center E of the ellipsoidal end of the expansion cavity 3, generating a new detonation hot spot through the shock wave focusing effect, igniting the compressed combustible mixture in the expansion cavity 3, and forming a second-stage detonation wave.

[0036] Step 6: The second-stage detonation wave burns the compressed combustible mixture in the expansion chamber 3 completely, and the combustion products are discharged backward through the straight section of the expansion chamber 3.

[0037] Step 7: Repeat steps 1 to 6 to make the power system work in a cycle.

[0038] During the power system cycle, parameters in the first straight-tube detonation combustion chamber 1, the second straight-tube detonation combustion chamber 2, and the expansion chamber 3 are simultaneously monitored. When it is determined that a detonation wave is formed in the first straight-tube detonation combustion chamber 1, the second straight-tube detonation combustion chamber 2, and the expansion chamber 3, and the detonation pressure in the expansion chamber 3 is higher than the detonation pressure in the first straight-tube detonation combustion chamber 1 and the second straight-tube detonation combustion chamber 2, the two-stage detonation is successful. Otherwise, parameter adjustments should be made to ensure the continuous formation of the two-stage detonation during the cycle.

[0039] One method is to use an ion probe to detect the flame reaction surface, thereby determining whether a detonation wave has formed.

[0040] In this scheme, the operating frequency of the two-stage detonation can be adjusted by changing the filling time of the combustible mixture and the ignition frequency of the active ignition.

[0041] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A device for achieving high-efficiency extraction of staged detonation energy, characterized in that, It includes a first straight-tube detonation combustion chamber (1), a second straight-tube detonation combustion chamber (2), and an expansion chamber (3), wherein: The front part of the inner cavity of the first straight tube detonation combustion chamber (1) and the second straight tube detonation combustion chamber (2) are respectively equipped with a first spiral structure (4) and a second spiral structure (5); the size of the first straight tube detonation combustion chamber (1) and the second straight tube detonation combustion chamber (2) are the same; the front end of the expansion cavity (3) is an ellipsoidal end, and the rest is a straight tube section; the rear ends of the first straight tube detonation combustion chamber (1) and the second straight tube detonation combustion chamber (2) are symmetrically connected to the ellipsoidal end of the expansion cavity (3), and the angle between their axes and the axis of the expansion cavity (3) is the same.

2. The device for achieving high efficient extraction of staged detonation energy according to claim 1, wherein, The angle between the axis of the first straight tube detonation combustion chamber (1) and the axis of the expansion chamber (3) is 30°~60°; the ratio of the diameter D3 of the straight tube section of the expansion chamber (3) to the diameter D1 of the first straight tube detonation combustion chamber (1) is 5~10.

3. The device for achieving high efficient extraction of staged detonation energy according to claim 1, wherein, Ignition positions C and D are respectively set near the front end of the first straight tube detonation combustion chamber (1) and the second straight tube detonation combustion chamber (2).

4. The apparatus for efficient extraction of staged detonation energy according to claim 1, characterized in that, Parameter acquisition units, including ion probes and pressure sensors, are installed in the first straight-tube detonation combustion chamber (1), the second straight-tube detonation combustion chamber (2), and the expansion chamber (3). The ion probes are used to detect the flame reaction surface at their location to determine whether a detonation wave is generated. The pressure sensors are used to detect the pressure at their location.

5. A method for achieving high efficiency extraction of staged detonation energy, characterized by, include: Step 1: A combustible mixture is introduced into the head A and B of the first straight tube detonation combustion chamber (1) and the second straight tube detonation combustion chamber (2) to fill the first straight tube detonation combustion chamber (1), the second straight tube detonation combustion chamber (2) and the expansion chamber (3); Step 2: Simultaneously ignite the combustible mixture at ignition positions C and D in the first straight-tube detonation combustion chamber (1) and the second straight-tube detonation combustion chamber (2); Step 3: After the ignited combustible mixture is accelerated by the turbulence of the first spiral structure (4) and the second spiral structure (5), it forms a first-stage detonation wave that propagates toward the expansion cavity (3). Step 4: After the first-stage detonation wave propagates to the ellipsoidal end of the expansion cavity (3), the detonation wave decouples due to the sudden expansion of the diameter of the propagation channel, and becomes a normal shock wave and a chemical reaction zone. The normal shock wave enters the expansion cavity first and compresses the combustible mixture that has not yet burned and is filled into the expansion cavity (3). Step 5: The decoupled normal shock waves meet and collide at the center E of the ellipsoidal end of the expansion cavity (3), generating a new detonation hot spot through the shock wave focusing effect, igniting the compressed combustible mixture in the expansion cavity (3), and forming a second-stage detonation wave. Step 6: The second-stage detonation wave burns the compressed combustible mixture in the expansion chamber (3), and the combustion products are discharged to the rear through the straight section of the expansion chamber (3). Step 7: Repeat steps 1 to 6 to make the power system carrying the extraction device work in a cycle.

6. The method of achieving high-efficiency extraction of staged detonation energy according to claim 5, wherein, During the power system cycle, the parameters in the first straight-tube detonation combustion chamber (1), the second straight-tube detonation combustion chamber (2), and the expansion chamber (3) are detected simultaneously. When it is determined that a detonation wave is formed in the first straight-tube detonation combustion chamber (1), the second straight-tube detonation combustion chamber (2), and the expansion chamber (3), and the detonation pressure in the expansion chamber (3) is higher than the detonation pressure in the first straight-tube detonation combustion chamber (1) and the second straight-tube detonation combustion chamber (2), the two-stage detonation is successful.

7. The method of achieving high-efficiency extraction of staged detonation energy according to claim 5, wherein, The operating frequency of the two-stage detonation can be adjusted by changing the filling time of the combustible mixture and the ignition frequency of the active ignition.

8. The method of achieving high-efficiency extraction of staged detonation energy according to claim 5, wherein, The combustible mixture is a gas mixture formed by mixing combustible gas with air or oxygen at points A and B of the head; or: The combustible mixture is a two-phase fluid formed by mixing a combustible liquid with air or oxygen at points A and B in the head after atomization.

9. A power system characterized by, The power system is equipped with the device according to any one of claims 1-4 and operates cyclically in accordance with the method according to any one of claims 5-8.

10. A pulse detonation engine characterized by, The engine uses the power system described in claim 9.

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