A method of flame acceleration with pulse jet resonance enhancement and DDT

Abstract

The present application belongs to the technical field of engine, and particularly relates to a method and device for enhancing flame acceleration and DDT by pulse jet flow resonance, comprising the following steps: obtaining the combustion chamber eigenfrequency of a combustion chamber; setting the jet flow frequency of the pulse jet flow according to the combustion chamber eigenfrequency, and the ratio of the combustion chamber eigenfrequency to the jet flow frequency being 1 / 1-3 / 2; injecting the pulse jet flow at the jet flow frequency along multiple radial directions of the inlet section of the combustion chamber, the multiple pulse jet flows generating pressure waves at the jet flow frequency, the pressure waves generated at the jet flow frequency forming a resonance effect with the combustion chamber, the pressure waves acting on the flame to accelerate the flame combustion and DDT conversion. Compared with the conventional jet flow injection method for increasing disturbance to accelerate flame combustion, the present application simplifies the structure, forms pressure waves by the pulse jet flow, and increases the pressure wave intensity through the resonance effect, greatly expanding the turbulent flow of the flame, and achieving better acceleration effect.

Description

Technical Field

[0001] This invention belongs to the field of engine technology, specifically relating to a method and apparatus for pulse jet resonance-enhanced flame acceleration and DDT. Background Technology

[0002] Current research on flame acceleration and DDT initiation in smooth combustion chambers, both domestically and internationally, includes methods such as using solid obstacles to accelerate turbulence generation and detonation transition (e.g., patent CN201910376650.9, "A pulse detonation engine combustion chamber and its initiation method"). Other methods utilize multiple continuous jet injections to enhance turbulent mixing and promote initiation (e.g., patent CN201620725025.2, "A jet-based pulse detonation engine detonation aid device"). The former method, by adding solid obstacles, causes a total pressure loss in the flow field, which is detrimental to overall engine performance improvement. While the latter method solves the problem of total pressure loss, it requires high-pressure gas to generate significant turbulence within the detonation tube for substantial acceleration and rapid detonation wave formation. Therefore, the high-pressure gas required for the jet needs to be high-pressure, and the number of jet orifices needs to be large, leading to a more complex combustion chamber structure and increased weight of the supporting equipment, which is detrimental to the engine's lightweight requirements. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method and apparatus for enhancing flame acceleration and DDT by pulse jet resonance while improving flame acceleration and accelerating DDT initiation effect under the premise of structural simplification.

[0004] This invention provides a method for pulse jet resonant enhanced flame acceleration and DDT, comprising the following steps:

[0005] Obtain the combustion chamber's intrinsic frequencies;

[0006] The jet frequency of the pulse jet is set according to the intrinsic frequency of the combustion chamber, and the ratio of the intrinsic frequency of the combustion chamber to the jet frequency is 1 / 1-3 / 2.

[0007] In the inlet section of the combustion chamber, pulse jets are injected along multiple radial directions at the jet frequency. Multiple pulse jets generate pressure waves at the jet frequency. The pressure waves generated at the jet frequency resonate with the combustion chamber. The pressure waves act on the flame, accelerating flame combustion and DDT conversion.

[0008] Furthermore, the ratio of the combustion chamber's intrinsic frequency to the jet frequency is 5 / 4.

[0009] Furthermore, injecting pulsed jets at multiple radial directions along the combustion chamber in the inlet section of the combustion chamber at a jet frequency includes:

[0010] Pulsed jets are injected at the jet frequency along multiple radial directions of the combustion chamber, and these multiple radial directions are arranged at equal angles with the combustion chamber axis as the center.

[0011] Furthermore, the method also includes:

[0012] Monitor the axial pressure within the combustion zone of the combustion chamber, analyze the detected axial pressure, and adjust the jet frequency accordingly.

[0013] The present invention also provides a device for pulse jet resonance enhanced flame acceleration and DDT, comprising a combustion chamber, wherein the combustion chamber is arranged in sequence along the axial direction as an inlet section, a jet section, an ignition section, a combustion section and an outlet section, and the jet section is provided with a plurality of jet injection holes arranged in a ring array along the axial direction.

[0014] Furthermore, the end face of the inlet section is provided with a switch device for opening and closing the inlet.

[0015] Furthermore, it also includes multiple pressure sensors arranged equidistantly along the combustion section axis.

[0016] Furthermore, the inner wall of the combustion chamber is a smooth cylindrical surface.

[0017] Furthermore, the jet injection orifice injects air.

[0018] The beneficial effects of this invention are as follows: This invention generates pressure waves at a specific frequency using a pulsed jet. A portion of these pressure waves travels along the combustion chamber axis from the inlet section to the outlet section. Because these pressure waves are generated at a radio frequency, they resonate with the combustion chamber, thereby enhancing the pressure waves. First, the enhanced pressure waves interact with the flame within the combustion section, strengthening the DDT process and increasing the intensity of the flame front. Furthermore, the multiple pressure waves generated at this frequency continuously act on the flame, strengthening the flow field behind the flame front and further promoting flame acceleration. Second, after passing through the combustion section, the pressure waves heat the combustion chamber, enhancing combustion. This invention significantly increases the flame acceleration propagation distance and shortens the time, while simultaneously accelerating the transition from turbulent combustion to detonation. This is particularly important for high-frequency detonation initiation of detonation engines under real-world conditions.

[0019] Furthermore, the pressure wave also disturbs the combustion flame when it acts on it, thus accelerating combustion from another perspective. Compared to the traditional method of increasing disturbance and accelerating combustion through jet injection, this invention, while retaining the disturbance of the flame, utilizes the resonance effect to enhance the intensity of the pressure wave, greatly improving the turbulence of the flame and resulting in a better acceleration effect. Moreover, it requires a lower number of pulse jets and lower flow rate, which is more conducive to meeting the lightweight requirements in the engine field. Attached Figure Description

[0020] Appendix Figure 1 This is a flowchart illustrating the method in this invention;

[0021] Appendix Figure 2 This is a schematic diagram of the device in this invention.

[0022] In the diagram, 1-combustion chamber; 11-inlet section; 12-jet section; 13-ignition section; 14-combustion section; 15-outlet section; 2-jet injection hole; 3-pressure sensor. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0025] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0026] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two elements or the interaction between two elements, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0027] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0028] As attached Figure 1 and attached Figure 2 As shown, the present invention provides a method for pulse jet resonant enhanced flame acceleration and DDT, comprising the following steps:

[0029] The combustion chamber eigenfrequency of combustion chamber 1 is obtained, wherein the combustion chamber eigenfrequency can be obtained in real time by a sensing device or can be known in advance by product parameters;

[0030] The jet frequency of the pulse jet is set according to the intrinsic frequency of the combustion chamber. The ratio of the intrinsic frequency of the combustion chamber to the jet frequency is 1 / 1 to 3 / 2. This is used to make the pressure wave formed by the pulse jet interact with the combustion flame at a jet frequency close to the intrinsic frequency of the flame.

[0031] In the inlet section 11 of the combustion chamber 1, pulse jets are injected at multiple radial directions along the combustion chamber 1 at the jet frequency. The multiple pulse jets generate pressure waves at the jet frequency. The pressure waves generated at the jet frequency resonate with the combustion chamber 1. The pressure waves act on the flame, accelerating flame combustion and DDT conversion.

[0032] This invention generates pressure waves at a specific frequency using a pulsed jet. A portion of these pressure waves travels along the combustion chamber axis from the inlet section 11 to the outlet section 15. Because the pressure waves are generated at a radio frequency, they resonate with the combustion chamber, thus enhancing their intensity. Firstly, the enhanced pressure waves, along with the flame within the combustion section 14, intensify the DDT process, increasing the intensity of the flame front. Furthermore, the multiple pressure waves generated at this frequency continuously act on the flame, strengthening the flow field behind the flame front and further promoting flame acceleration. Secondly, after passing through the combustion section 14, the pressure waves heat the combustion chamber, enhancing combustion. This invention significantly increases the flame acceleration propagation distance and shortens the time, while simultaneously accelerating the transition from turbulent combustion to detonation. This is particularly important for high-frequency detonation initiation of detonation engines under real-world conditions.

[0033] Furthermore, the pressure wave also disturbs the combustion flame when it acts on it, thus accelerating combustion from another perspective. Compared to the traditional method of increasing disturbance and accelerating combustion through jet injection, this invention, while retaining the disturbance of the flame, utilizes the resonance effect to enhance the intensity of the pressure wave, greatly improving the turbulence of the flame and resulting in a better acceleration effect. Moreover, it requires a lower number of pulse jets and lower flow rate, which is more conducive to meeting the lightweight requirements in the engine field.

[0034] In one embodiment, the ratio of the combustion chamber intrinsic frequency to the jet frequency is 5 / 4. Simulation studies have shown that setting the jet frequency to 5 / 4T of the combustion chamber intrinsic frequency can achieve better flame acceleration and DDT conversion effects.

[0035] In one embodiment, injecting pulsed jets at a jet frequency along multiple radial directions of the combustion chamber 1 at the inlet section 11 of the combustion chamber 1 includes:

[0036] Pulsed jets are injected at jet frequency along multiple radial directions of combustion chamber 1. These multiple radial directions are arranged at equal angles with the axis of combustion chamber 1 as the center. The multiple pulsed jets work on the same cross section, which can amplify the initial pressure wave. At the same time, the multiple pulsed jets are arranged at equal angles with the axis of combustion chamber 1 as the center, which can improve the uniformity of the pressure wave in all directions, so that the combustion flame can be effectively accelerated in all directions.

[0037] In one embodiment, the method further includes:

[0038] The axial pressure within the combustion section of combustion chamber 1 is monitored, and the jet frequency is adjusted based on the detected axial pressure. Pressure detection measures the pressure on the wall of combustion chamber 1, allowing for the detection of flame acceleration and propagation. This enables closed-loop control. By monitoring the combustion flame, data is fed back to the controller, which then adjusts the jet frequency to further enhance acceleration. Specifically, the closer the jet frequency is to the intrinsic frequency of combustion chamber 1, the larger the amplitude of the pressure wave generated by resonance, which is beneficial for accelerating flame propagation. The jet frequency adjustment primarily controls the intensity of resonance. The closer it is to the intrinsic frequency of combustion chamber 1, the stronger the resonance effect, resulting in a larger pressure wave amplitude and further promoting flame acceleration. Therefore, closed-loop control can be achieved based on changes in detected pressure. When the detected pressure amplitude decreases, the jet frequency is appropriately increased to approach the intrinsic frequency; when the detected pressure amplitude increases, the jet frequency is appropriately decreased, until the detected pressure amplitude reaches the set range.

[0039] The present invention also provides a device for pulse jet resonance enhanced flame acceleration and DDT, comprising a combustion chamber 1, wherein the combustion chamber 1 comprises, in the order of inlet section 11, jet section 12, ignition section 13, combustion section 14 and outlet section 15 along the axial direction, and the jet section 12 is provided with a plurality of jet injection holes 2 arranged in a ring array along the axial direction.

[0040] Among them, the jet injection hole 2 is used to inject pulse jets. Multiple jet injection holes 2 in the axial annular array inject pulse jets at a specific frequency, which can form a pressure wave at a specific frequency. This pressure wave passes through the ignition section 13, the combustion section 14 and the outlet section 15 in sequence. In the combustion section 14, it interacts with its combustion flame, and the specific frequency forms a resonance effect with the intrinsic frequency of the combustion chamber, which amplifies the intensity of the pressure wave and further accelerates the flame combustion and DDT initiation.

[0041] In one embodiment, the end face of the inlet section 11 is provided with a switch device for opening and closing the inlet. In this embodiment, fuel is intermittently injected into the combustion chamber 1 from the end face of the inlet section 11. When the switch device is in the closed state, the inlet section 11 is in the closed state, and the pressure resonance effect can exert its maximum effect at the closed end. Therefore, the flame acceleration effect can be effectively improved at this time. In addition, the closed end face of the inlet section 11 can also reflect the pressure wave moving towards the inlet section 11. This pressure wave interacts with the combustion flame again, further improving the acceleration effect. In this embodiment, the jet injection hole 2 is preferably located close to the switch device to maximize the use of the wall surface reflecting the pressure wave after the switch device is closed.

[0042] The device for pulse jet resonance-enhanced flame acceleration and DDT also includes multiple pressure sensors 3 equidistantly arranged along the axis of the combustion section 14, used to monitor the combustion flame in the combustion section and detect the state of flame acceleration propagation.

[0043] The inner wall of the combustion chamber 1 is a smooth cylindrical surface, which facilitates the propagation of pressure waves and reduces the propagation loss of fuel, air and pressure waves.

[0044] The jet injection hole 2 injects air, which not only forms a pressure wave but also assists in combustion, thus satisfying the combustion conditions of the combustion chamber 1.

[0045] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

Claims

1. A method for pulse jet resonant enhancement of flame acceleration and DDT, characterized in that, Includes the following steps: Obtain the combustion chamber's intrinsic frequencies; The jet frequency of the pulse jet is set according to the intrinsic frequency of the combustion chamber, and the ratio of the intrinsic frequency of the combustion chamber to the jet frequency is 1 / 1-3 / 2. In the inlet section of the combustion chamber, pulse jets are injected along multiple radial directions at the jet frequency. Multiple pulse jets generate pressure waves at the jet frequency. The pressure waves generated at the jet frequency resonate with the combustion chamber. The pressure waves act on the flame, accelerating flame combustion and DDT conversion.

2. The method for pulse jet resonance-enhanced flame acceleration and DDT as described in claim 1, characterized in that, The ratio of the combustion chamber's intrinsic frequency to the jet frequency is 5 / 4.

3. The method for pulse jet resonance-enhanced flame acceleration and DDT as described in claim 1, characterized in that, Pulsed jets are injected at jet frequencies in multiple radial directions along the inlet section of the combustion chamber, including: Pulsed jets are injected at the jet frequency along multiple radial directions of the combustion chamber, and these multiple radial directions are arranged at equal angles with the combustion chamber axis as the center.

4. The method for pulse jet resonant enhanced flame acceleration and DDT as described in any one of claims 1-3, characterized in that, The method further includes: Monitor the axial pressure within the combustion zone of the combustion chamber, analyze the detected axial pressure, and adjust the jet frequency accordingly.

5. A device for pulse jet resonant enhancement of flame acceleration and DDT, characterized in that, The method of pulse jet resonance enhanced flame acceleration and DDT as described in any one of claims 1-4 includes a combustion chamber, wherein the combustion chamber is sequentially arranged along the axial direction as an inlet section, a jet section, an ignition section, a combustion section and an outlet section, and the jet section is provided with a plurality of jet injection holes arranged in a ring array along the axial direction.

6. The apparatus for pulse jet resonance-enhanced flame acceleration and DDT as described in claim 5, characterized in that, The inlet section end face is provided with a switch device for opening and closing the inlet.

7. The apparatus for pulse jet resonance-enhanced flame acceleration and DDT as described in claim 5, characterized in that, It also includes multiple pressure sensors arranged at equal intervals along the combustion section axis.

8. The apparatus for pulse jet resonance-enhanced flame acceleration and DDT as described in claim 5, characterized in that, The inner wall of the combustion chamber is a smooth cylindrical surface.

9. The apparatus for pulse jet resonance-enhanced flame acceleration and DDT as described in claim 5, characterized in that, The jet injection orifice injects air.

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