A disc-shaped combustion chamber for studying the stable propagation condition of rotating detonation wave

Abstract

The application discloses a disc type combustion chamber for studying stable propagation conditions of detonation waves, comprising a pre-detonation tube, a disc type combustion chamber, a baffle, and a groove disc. The pre-detonation tube is a circular channel. A first air inlet is arranged on an outer wall surface of one end of the pre-detonation tube. The other end of the pre-detonation tube is communicated with the disc type combustion chamber. The disc type combustion chamber is divided into an upper layer and a lower layer by the groove disc. The groove disc is provided with a plurality of equidistant groove rings for mounting different baffles. The different baffles have a plurality of specifications and jointly form a propagation channel of a rotating detonation wave with an inner wall surface of the upper layer of the disc type combustion chamber. An actuator is mounted on a corresponding groove ring according to a mounting position of the baffle. The baffle can be separated from the upper layer of the disc type combustion chamber to the lower layer of the disc type combustion chamber by the actuator. The width of the propagation channel of the detonation wave can be changed by changing the size and mounting position of the baffle on the groove disc, so that the minimum critical combustion chamber channel width range required for stable propagation of the rotating detonation wave is explored.

Description

Technical Field

[0001] This invention relates to a disc-type combustion chamber for studying the stable propagation conditions of rotating detonation waves, belonging to the technical field of detonation wave propagation characteristics. Background Technology

[0002] The Rotating Detonation Engine (RDE) is a novel power plant based on detonation combustion. Compared with traditional aerospace engines based on detonation combustion, it has advantages such as simple structure, high thermal cycle efficiency, and high specific impulse, making it a current research hotspot and frontier in the field of aerospace propulsion. The detonation wave is a supersonic combustion wave strongly coupled with a leading shock wave and a rear chemical reaction zone. The RDE utilizes the continuous circumferential rotation of the detonation wave to drive the combustion of a fresh mixture and generate high-temperature, high-pressure gas. This gas expands and is ejected from the combustion chamber outlet, thus generating thrust.

[0003] The propagation environment of the detonation wave within a reversed-phase (RDE) system is highly complex. A key characteristic is the interaction between the combustion front of the high-temperature combustion products from the previous cycle and the fresh premixed gas, resulting in velocity and peak pressure losses. This loss is primarily influenced by fuel reactivity and combustion chamber width. Significant losses can lead to decoupling between the leading shock wave and the post-shock chemical reaction zone, ultimately extinguishing the detonation wave. In fact, for premixed fuels with specific compositions and equivalence ratios, there exists a minimum critical combustion chamber width. Only when the actual combustion chamber width exceeds this critical value can the rotating detonation wave propagate stably.

[0004] Currently, researchers typically conduct comparative experiments on combustion chambers of different sizes to determine the critical width of the combustion chamber. However, manufacturing combustion chambers of different sizes is costly, and conducting experiments on different combustion chambers is cumbersome. More importantly, the accuracy of the critical channel width dimensional obtained using this method is relatively low. Therefore, it is necessary to provide an experimental apparatus that can conveniently estimate the range of the critical channel width of the combustion chamber. Summary of the Invention

[0005] The purpose of this invention is to propose an experimental apparatus that can determine the minimum range of combustion chamber passage width required to maintain stable propagation of rotating detonation waves, addressing the issues of velocity deficit and peak pressure deficit in rotating detonation waves when studying the conditions for stable propagation of rotating detonation waves.

[0006] The technical solution adopted in this invention is: a disc-type combustion chamber for studying the stable propagation conditions of detonation waves, comprising: an electric spark igniter, a pre-detonation tube, a first air inlet, at least two first pressure sensors, a disc combustion chamber, multiple second pressure sensors, a second air inlet, an air outlet, a baffle plate, a slotted plate, an actuator, and a sealing gasket.

[0007] The pre-detonation tube is a circular channel. A first air inlet is located on the outer wall of one end of the pre-detonation tube for introducing the premixed fuel required for the test. The other end of the pre-detonation tube is connected to a disc combustion chamber. An electric spark igniter is installed on the inner wall of one end of the pre-detonation tube to ignite the fuel and generate a flame. At least two first pressure sensors are installed on the outer wall of the end of the pre-detonation tube.

[0008] The disc combustion chamber is divided into upper and lower layers by a slotted disc. The second air inlet is located at the center of the upper surface of the disc combustion chamber. The slotted disc has multiple equally spaced slotted rings for installing different baffles. The different baffles have multiple specifications and together with the inner wall of the upper disc combustion chamber, they form a propagation channel for the rotating detonation wave. The baffles are sealed at the joint with the slotted rings. Multiple second pressure sensors are sequentially arranged on the outer wall of the disc combustion chamber. The inner wall of the upper surface of the disc combustion chamber has grooves corresponding to the slotted rings on the slotted disc. Sealing gaskets are installed in the grooves. The actuator is installed on the corresponding slotted ring according to the baffle installation position. The actuator can pull the baffle from the upper disc combustion chamber to the lower disc combustion chamber. The air outlet is arranged on the outer wall of the disc combustion chamber.

[0009] Furthermore, it also includes a detonation triggering device, which is arranged inside the pre-detonation tube to accelerate the flame to form a detonation wave.

[0010] Furthermore, the upper wall of the combustion chamber is made of quartz glass.

[0011] Furthermore, the actuator is a diaphragm pneumatic actuator.

[0012] Furthermore, multiple second pressure sensors are equally spaced on the outer wall of the disc combustion chamber.

[0013] Furthermore, in the entire upper and lower disc combustion chamber, a built-in circular grooved plate is set in the middle of the disc combustion chamber, and grooved rings are set at equal intervals within a range of 25mm-65mm from the center of the circular grooved plate, with a distance of 10mm between each two adjacent grooved rings.

[0014] The working method of the disc-type combustion chamber based on the above research on the stable propagation conditions of detonation waves includes the following steps:

[0015] S1: Generating a stable detonation wave in the pre-detonation tube and the disc combustion chamber: Premixed gas is introduced through the first air inlet. After the premixed gas fills the pre-detonation tube and the disc combustion chamber, the electric spark igniter is ignited. The combustion wave is generated at one end of the pre-detonation tube and propagates to the other end. The speed of the combustion wave when it reaches the end of the pre-detonation tube is calculated based on the time interval of the high-frequency dynamic pressure signal received by the first pressure sensor at the end of the pre-detonation tube and the distance between the two first pressure sensors. The magnitude of the combustion wave speed determines whether the combustion wave is a detonation wave. If a stable detonation wave can be generated in both the pre-detonation tube and the disc combustion chamber, the combustion products in the pre-detonation tube and the disc combustion chamber are emptied, and the process proceeds to step 2. If a stable detonation wave cannot be generated, the initial parameters are changed and the experiment is repeated.

[0016] S2: Constructing a disc combustion chamber with the minimum channel width: At the beginning of the experiment, install the smallest size baffle on the corresponding groove ring to construct a disc combustion chamber with the minimum channel width;

[0017] S3: Constructing a weak constraint boundary: Inert gas is injected through the second air inlet above the disc combustion chamber, and premixed fuel gas is introduced through the first air inlet. The inert gas completely fills the space constructed by the baffle. The pneumatic actuator is activated to drive the baffle to move downward, and the baffle is drawn away from the upper combustion chamber.

[0018] S4: Determine the critical combustion chamber width range that enables the rotating detonation wave to propagate stably: Under the determined test conditions, start the electric spark igniter and determine whether the detonation wave can propagate stably after entering the disc combustion chamber from the pre-detonation tube. If the detonation wave can still propagate stably in the disc combustion chamber, increase the radius of the baffle plate in sequence and repeat steps 2 and 3 to observe whether the detonation wave propagates stably in the disc combustion chamber until the rotating detonation wave in the disc combustion chamber can no longer propagate stably. The distance between the baffle plate where the detonation wave cannot propagate stably and the wall of the disc combustion chamber is the minimum critical combustion chamber width range that maintains the stable propagation of the rotating detonation wave.

[0019] Furthermore, the initial parameters in S1 include ignition temperature, fuel type, pressure inside the disc combustion chamber, and size of the disc combustion chamber.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a novel rotating detonation disc combustion chamber, which adds a slotted plate and a baffle plate to the existing disc combustion chamber. By changing the size and specifications of the baffle plate and its installation position on the slotted plate, the width of the detonation wave propagation channel can be changed, thereby exploring the minimum critical combustion chamber channel width range required for stable propagation of the rotating detonation wave. Compared with the traditional device, this device greatly simplifies the step of redesigning the combustion chamber.

[0021] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0022] Figure 1 This is a top view of the disc-shaped combustion chamber of the present invention.

[0023] Figure 2 This is a side view of the disc-shaped combustion chamber of the present invention.

[0024] Figure 3 This is a schematic diagram of the process of the baffle being removed from the upper combustion chamber. Detailed Implementation

[0025] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0026] Figure 1-2 This is a schematic diagram of the structure of the novel disc-shaped combustion chamber proposed in this invention. The disc-shaped combustion chamber includes: an electric spark igniter 1, a detonation device 2, a pre-detonation tube 3, a first air inlet 14, a first pressure sensor 13, a disc combustion chamber 15, a second pressure sensor 11, a second air inlet 12, an air outlet 16, a partition 17, a grooved plate 18, quartz glass 19, a pneumatic actuator 20, and a sealing gasket 21.

[0027] The pre-detonation tube 3 is a small-diameter circular channel. The air inlet 14 is located on the outer wall of the left end of the pre-detonation tube 3 for introducing the premixed fuel required for the test. An electric spark igniter 1 is installed on the inner wall of the leftmost end of the pre-detonation tube 3 to ignite the fuel and generate a flame. A detonation acceleration device 2 is arranged inside the pre-detonation tube 3 to accelerate the flame and form a detonation wave. A first pressure sensor 13 is installed on the outer wall of the end of the pre-detonation tube 3. The pressure sensor 13 can receive the high-frequency dynamic pressure signal generated when the combustion wave propagates to the end of the pre-detonation tube 3, thereby calculating the propagation speed of the combustion wave and determining whether the combustion wave inside the pre-detonation tube 3 is a detonation wave.

[0028] The disc combustion chamber 15 is a circular combustion chamber divided into upper and lower layers by the slotted plate 18, and is connected to the pre-detonation tube 3 through a flange. The second air inlet 12 is located at the center of the upper surface of the disc combustion chamber 15 and is used to introduce inert gas. The slotted plate 18 has multiple equally spaced slotted rings (the distance between adjacent slotted rings is, for example, 10 mm) for installing baffles 17. The baffles 17 have multiple specifications and together with the inner wall surface of the disc combustion chamber 15, they form a propagation channel for the rotating detonation wave. Furthermore, the joint between the baffles 17 and the slotted rings is also coated with heat-resistant sealant to ensure the airtightness of the device. The second pressure sensor 11 is a group of pressure sensors, evenly spaced on the outer wall of the disc combustion chamber 15, used to indirectly measure the propagation speed of the rotating detonation wave inside the disc combustion chamber, thereby determining whether the rotating detonation wave is propagating stably. The quartz glass 19 installed on the upper wall of the combustion chamber also facilitates observation and recording by the high-speed camera. At the same time, the quartz glass plate has grooves corresponding to the grooved rings on the slotted plate. The sealing gaskets 21 in the grooves are used to meet the airtightness requirements of the device when the partition 17 is not removed. The pneumatic actuator 20 is a common diaphragm pneumatic actuator. Its working principle is that when air is drawn into the gas chamber, the diaphragm contracts, and the connecting rod connected to it moves downward, driving the partition 17 downward. The actuator is installed on the corresponding grooved ring according to the installation position of the partition 17, and is used to remove the partition 17 before the detonation wave comes into contact with the inert gas. The exhaust port 16 is arranged on the outer wall of the disc combustion chamber 15, at a certain distance from the second pressure sensor 11, and is used to discharge the exhaust gas generated in the experiment.

[0029] The working process of this invention is described below:

[0030] S1: A stable detonation wave is generated within the pre-detonation tube 3 and the disc combustion chamber 15. Premixed combustion gas is introduced through the air inlet 14. After the gas fills the pre-detonation tube 3 and the disc combustion chamber 15, the electric spark igniter 1 is ignited. The combustion wave is generated at the left end of the pre-detonation tube 3 and, through the action of the detonation accelerator 2, propagates rapidly to the end of the pre-detonation tube 3. The velocity of the combustion wave propagating to the end of the pre-detonation tube 3 is calculated based on the time interval of the high-frequency dynamic pressure signal received by the first pressure sensor 13 at the end of the pre-detonation tube 3 and the distance between the two first pressure sensors 13. The magnitude of the combustion wave velocity determines whether the combustion wave is a detonation wave. At the same time, it is determined whether the detonation wave can propagate stably in the disc combustion chamber 15 without extinguishing. If a stable detonation wave can be generated in both the pre-detonation tube 3 and the disc combustion chamber 15, the combustion products in the pre-detonation tube 3 and the disc combustion chamber 15 are emptied, and the subsequent steps are continued. If a stable detonation wave cannot be generated, the initial parameters (including the ignition temperature of the igniter 1, the fuel type, the pressure inside the disc combustion chamber, and the size of the disc combustion chamber) are changed again before the experiment is repeated.

[0031] S2: Constructing a disc combustion chamber with the minimum channel width. Under the premise that a stable detonation wave can be generated within the pre-detonation tube, the construction of a combustion chamber with the minimum channel width begins. In the entire double-layer combustion chamber, an internal circular grooved disk 18 is positioned in the center of the disc combustion chamber, and grooved rings are evenly spaced within a range of 25mm-65mm from the center of the circular grooved disk 18, with a distance of 10mm between every two adjacent grooved rings. At the start of the experiment, the smallest specification partition plate 17 is installed on the corresponding grooved ring, thus constructing the disc combustion chamber with the minimum channel width. Figure 1 The example provides installation diagrams for multiple partitions, but in actual experiments, only one partition of the corresponding specification needs to be installed, such as... Figure 2 (As shown).

[0032] S3: Construct a weak constraint boundary. Inert gas is injected through the second air inlet 12 above the disc combustion chamber, and premixed combustion gas is introduced through the air inlet 14. The inert gas completely fills the space constructed by the partition, activating the pneumatic actuator 20, which drives the partition 17 connected to the connecting rod to move downwards (the movement process is as follows). Figure 3 As shown), the baffle 17 is drawn away from the upper combustion chamber (the process of the pneumatic actuator drawing out the baffle is as follows). Figure 3 As shown), considering the propagation speed of the detonation wave and the diffusion rate of the inert gas, the baffle 17 is removed in advance and the igniter 3 is started immediately to generate a stable propagating detonation wave. Finally, the detonation wave propagates to the disc combustion chamber and comes into contact with the inert gas. The inert gas then becomes the weakly constrained boundary for the lateral expansion of the detonation wave propagating in the bend.

[0033] S4: Determine the critical combustion chamber width range that allows the rotating detonation wave to propagate stably. Under the determined test conditions, start the electric spark igniter 1 and determine whether the detonation wave can propagate stably after entering the disc combustion chamber 15 from the pre-detonation tube 3. The determination method is to observe by taking pictures through the quartz glass 19 with a high-speed camera or to judge based on the pressure value of the second pressure sensor. If the detonation wave can still propagate stably in the disc combustion chamber, then increase the radius of the baffle 17 in turn and repeat steps 2 and 3 to observe whether the detonation wave propagates stably in the disc combustion chamber 15, until the rotating detonation wave in the disc combustion chamber 15 can no longer propagate stably. The distance between the baffle where the detonation wave cannot propagate stably and the wall of the disc combustion chamber 15 is the minimum critical combustion chamber width range for maintaining the stable propagation of the rotating detonation wave.

[0034] The above description is merely an advantageous embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A disc-shaped combustion chamber for studying the stable propagation conditions of detonation waves, characterized in that, include: Electric spark igniter (1), pre-detonation tube (3), first air inlet (14), at least two first pressure sensors (13), disc combustion chamber (15), multiple second pressure sensors, second air inlet (12), air outlet (16), partition (17), slotted plate (18), pneumatic actuator (20), sealing gasket (21), The pre-detonation tube (3) is a circular channel. A first air inlet (14) is located on the outer wall of one end of the pre-detonation tube (3) for introducing the premixed fuel required for the test. The other end of the pre-detonation tube (3) is connected to the disc combustion chamber (15). An electric spark igniter (1) is installed on the inner wall of one end of the pre-detonation tube (3) for igniting the fuel to generate a flame. At least two first pressure sensors (13) are installed on the outer wall of the end of the pre-detonation tube (3). The disc combustion chamber (15) is a disc combustion chamber divided into upper and lower layers by the slotted disc (18). The second air inlet (12) is located at the center of the upper surface of the disc combustion chamber (15). The slotted disc (18) has multiple equally spaced slotted rings for installing different baffles (17). The different baffles (17) have multiple specifications and together with the inner wall of the upper disc combustion chamber, they form a propagation channel for the rotating detonation wave. The baffles (17) are sealed at the joint with the slotted rings. Multiple second pressure sensors are installed sequentially. At the outer wall of the disc combustion chamber (15), there is a groove on the inner wall of the upper surface of the disc combustion chamber (15) that corresponds to the groove ring on the groove plate (18). A sealing gasket (21) is provided in the groove. The pneumatic actuator (20) is installed on the corresponding groove ring according to the installation position of the partition plate (17). The partition plate (17) can be pulled from the upper disc combustion chamber to the lower disc combustion chamber by the pneumatic actuator (20). The air outlet (16) is arranged at the outer wall of the disc combustion chamber (15).

2. The disc-shaped combustion chamber for studying the stable propagation conditions of detonation waves according to claim 1, characterized in that, It also includes a detonation triggering device (2), which is arranged inside the pre-detonation tube (3) to accelerate the flame to form a detonation wave.

3. The disc-shaped combustion chamber for studying the stable propagation conditions of detonation waves according to claim 1, characterized in that, The upper wall of the combustion chamber is made of quartz glass (19).

4. The disc-shaped combustion chamber for studying the stable propagation conditions of detonation waves according to claim 1, characterized in that, The pneumatic actuator (20) is a diaphragm pneumatic actuator.

5. The disc-shaped combustion chamber for studying the stable propagation conditions of detonation waves according to claim 1, characterized in that, Multiple second pressure sensors are equally spaced on the outer wall of the disc combustion chamber (15).

6. The disc-shaped combustion chamber for studying the stable propagation conditions of detonation waves according to claim 1, characterized in that, In the entire upper and lower disc combustion chamber, the built-in grooved plate (18) is set in the middle of the disc combustion chamber, and grooved rings are set at equal intervals within a range of 25mm-65mm from the center of the grooved plate (18), with a distance of 10mm between each two adjacent grooved rings.

7. The working method of the disc-type combustion chamber for studying the stable propagation conditions of detonation waves according to any one of claims 1-6, characterized in that, Includes the following steps: S1: A stable detonation wave is generated in the pre-detonation tube (3) and the disc combustion chamber (15): Premixed gas is introduced from the first air inlet (14). After the premixed gas fills the pre-detonation tube (3) and the disc combustion chamber (15), the electric spark igniter (1) is ignited. The combustion wave is generated at one end of the pre-detonation tube (3) and propagates to the other end of the pre-detonation tube (3). The time interval of the high-frequency dynamic pressure signal received by the first pressure sensor (13) at the end of the pre-detonation tube (3) and the combustion wave are determined according to the time interval of the high-frequency dynamic pressure signal received by the first pressure sensor (13) at the end of the pre-detonation tube (3). The distance between the two first pressure sensors (13) is used to calculate the speed at which the combustion wave propagates to the end of the pre-detonation tube (3). The magnitude of the combustion wave speed determines whether the combustion wave is a detonation wave. If a stable detonation wave can be generated in both the pre-detonation tube (3) and the disc combustion chamber (15), the combustion products in the pre-detonation tube (3) and the disc combustion chamber (15) are emptied, and the process proceeds to step S2. If a stable detonation wave cannot be generated, the initial parameters are changed and the experiment is repeated. S2: Constructing a disc combustion chamber with the minimum channel width: At the beginning of the experiment, the smallest size partition (17) is installed on the corresponding groove ring, thus constructing a disc combustion chamber with the minimum channel width; S3: Constructing a weak constraint boundary: Inert gas is injected through the second air inlet (12) above the disc combustion chamber, and premixed gas is introduced through the first air inlet (14). The inert gas completely fills the space constructed by the partition. The pneumatic actuator (20) is activated, which drives the partition (17) to move downward. The partition (17) is extracted from the upper combustion chamber. S4: Determine the critical combustion chamber width range that enables the rotating detonation wave to propagate stably: Under the determined test conditions, start the electric spark igniter (1) and determine whether the detonation wave can propagate stably after entering the disc combustion chamber (15) from the pre-detonation tube (3). If the detonation wave can still propagate stably in the disc combustion chamber, increase the radius of the baffle (17) in sequence and repeat steps S2 and S3 to observe whether the detonation wave propagates stably in the disc combustion chamber (15) until the rotating detonation wave in the disc combustion chamber (15) cannot propagate stably. At this time, the distance between the baffle (17) where the detonation wave cannot propagate stably and the wall of the disc combustion chamber (15) is the minimum critical combustion chamber width range that maintains the stable propagation of the rotating detonation wave.

8. The method according to claim 7, characterized in that, The initial parameters in S1 include the ignition temperature of the igniter (1), the type of fuel, the pressure inside the disc combustion chamber, and the size of the disc combustion chamber.

Images