A shock wave focusing detonation device with a central cone and its operating method

Abstract

This invention discloses a shock wave focusing detonation device with a central cone. The internal space formed by the front section of the main detonation tube and the central cone has an axial air intake at the leading edge. After passing through a bend, the mixed gas enters the detonation tube along the tangent of the generatrix of the central cone. The pre-detonation tube that generates the hot jet is moved to the outer wall of the front section of the main detonation tube, and the jet hole is separated from the air inlet. Continuous annular grooves or uniformly distributed small concave walls are opened on the conical surface of the central cone, so that the hot jet is injected from the jet hole into the main detonation tube and collides with the central cone to form a shock wave. By continuously focusing the shock wave on the grooves or small concave walls, the efficiency of jet ignition and detonation is accelerated, and a stable and reliable detonation wave is formed while reducing the DDT distance.

Description

Technical Field

[0001] This invention relates to high-frequency pulse detonation engine ignition and detonation technology, specifically a shock wave focusing detonation device with a central cone and its operating method. Background Technology

[0002] For existing military engines, constrained by material strength and structure, effectively improving the thrust-to-weight ratio has become a major technical challenge in the field of aero-engines. The development of unconventional new aero-engines has brought about a new revolution in the field of aviation. Pulse detonation engines (PDEs) exhibit numerous potential advantages in theory and application, including simple structure, light weight, high cycle thermal efficiency, and high thrust-to-weight ratio. However, the key to fully realizing the potential of pulse detonation engines lies in how to reliably initiate detonation waves at high frequencies.

[0003] Traditional pulse detonation engine models are typically concave cavity designs involving supersonic jet collisions and shock wave focusing. However, current experimental and numerical simulations have revealed several drawbacks to these models, including difficulty in generating shock waves through supersonic jet collisions, incompatibility with fresh mixture refilling and shock wave focusing structures, and a tendency for backpropagation during combustion. These limitations prevent traditional detonation models from meeting the needs of engineering applications.

[0004] Patent CN110905688A discloses a device for increasing the operating frequency of a pulse detonation engine using a non-flammable liquid. This device includes a liquid injection system, a fuel and oxidizer supply system, a detonation tube, an ignition device, and a system control method. By relying on the evaporation, heat absorption, and expansion of the non-flammable liquid, it achieves isolation between the high-temperature combusted products and the reactants in the next cycle during high-frequency operation of the pulse detonation engine. This avoids the decompression performance problem caused by the dilution of reactants due to traditional nitrogen isolation, thus improving the engine's operating frequency and performance. However, it still lags behind engineering application standards in addressing issues such as flame backpropagation and the difficulty in forming shock waves from supersonic jet collisions.

[0005] Patent CN110259601A discloses a pulse detonation engine combustion chamber structure and initiation method. This method involves a side opening at the tail end of a jet pipe embedded in the main detonation chamber, with spark plug ignition at the jet head. The hot jet carrying a large number of active groups enters the main detonation chamber from the side opening at the tail end and the right-end outlet, significantly amplifying the initial ignition energy. Simultaneously, the opening at the tail end of the jet pipe enables multi-point ignition, enhancing the collision and superposition of shock waves, increasing the intensity of the shock wave at the flame front, shortening the transition distance from deflagration to detonation (DDT) in the main detonation chamber, and improving the operating frequency. However, this method still does not solve the problem of difficult exhaust gas emission. Summary of the Invention

[0006] To address the challenges of generating shock waves from supersonic jet filling collisions in existing PDE models, including difficulties in refilling fresh gas mixtures, unsuitable shock wave focusing structures, and the tendency for back propagation during combustion, this invention proposes a shock wave focusing initiation device with a central cone.

[0007] The technical solution adopted in this invention is as follows:

[0008] A shock wave focusing detonation device with a central cone includes a front section of a main detonation tube, a rear section of a main detonation tube, and a central cone. The front section and the rear section of the main detonation tube are concentrically distributed with the central cone, and the central cone is disposed inside the front section of the main detonation tube. The front section and the rear section of the main detonation tube are connected by a flange. The outer surface of the front section of the main detonation tube is provided with a jet hole for injecting a thermal jet.

[0009] Preferably, the central cone is a concave cone shape, with its generatrix being the radius. R An arc of 90~100mm, with a central angle of... θ The angle is 40°~50°, and the height of the concave conical central cone is... h It is 70~80mm.

[0010] Preferably, the conical surface of the central cone is provided with an annular groove for shock wave focusing.

[0011] Preferably, the annular grooves are continuously distributed from the top to the bottom of the central cone and are arc-shaped, with a radius of curvature of [missing information]. r The radius is 1.5~3.5mm, and the central angle of the arc is... α The angle is 120°, and the centers of all the annular grooves are continuously distributed on the same arc as the generatrix of the central cone, with a radius of 120°. R 1 On a circle of 97~99mm.

[0012] Preferably, the central cone has uniformly distributed small concave wall surfaces on its conical surface.

[0013] Preferably, the concave wall is a portion of a spherical surface evenly distributed on the surface of the central cone, with a radius of 1.5~3.5mm and a solid angle of 240°. The centers of all the concave walls lie on a circle centered on the projection of the central cone axis onto the bottom surface.

[0014] Preferably, the outer surface of the front section of the main detonation tube is a stepped cylinder, and the front section of the inner surface of the front section of the main detonation tube has a circular arc radius. r 1 The annular bend is 6-8mm, and the middle section of the inner surface of the front section of the main detonation tube is a circular arc with a radius tangent to the front section. r 2 The spherical surface is 25~30mm in diameter, and the rear section of the inner surface of the front section of the main detonation tube is an inclined surface tangent to the middle section.

[0015] Preferably, the jet holes are distributed on the middle section of the inner surface of the front section of the main detonation tube, and their diameter is... d 1 The diameter is 6~10mm, and the outer surface of the front section of the main detonation tube at the corresponding position of the jet hole is provided with a diameter of 6~10mm. d 2 The boss is a circular boss with a diameter of 12-18mm, and the height of the circular boss relative to the outer surface is... a The diameter is 10~15mm, and the jet holes and the circular boss are concentrically distributed and 4~8 are evenly distributed around the front section of the main detonation tube.

[0016] A method for operating a shock wave focusing detonation device with a central cone, the method comprising:

[0017] Step 1: First, fix it to the ignition end of the engine to be ignited, and connect the gas intake pipe and high-pressure air intake pipe of the front mixing zone to the hot jet pipe of the ignition zone. The gas is introduced radially and the air is introduced axially.

[0018] Step 2: After installation, air and gas are introduced to mix them in the mixing zone. The mixed gas flows axially into the ignition zone, and at the same time, a hot jet is introduced from the hot jet pipe. The shock wave formed by the collision of the hot jet with the central cone is continuously focused on the annular groove, generating a stable and reliable detonation wave, and finally successfully igniting the mixed gas.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. This invention changes the traditional air intake method to air intake along the tangent direction of the generatrix of the central cone, so that the gas can better fill the main detonation tube along the inner wall surface. In the multi-cycle process, the newly filled gas can effectively discharge the combustion exhaust gas along the inner wall surface.

[0021] 2. In this invention, the pre-detonation tube is obliquely inserted into the outer wall of the main detonation tube, and a hot jet is injected from the jet hole at the front of the main detonation tube into the main detonation tube, thus separating the air inlet from the jet hole and solving the problem of the same inlet function requirements being contradictory in the original model in order to reduce control complexity.

[0022] 3. The present invention has an annular groove or uniformly distributed small concave walls on the central cone. The hot jet injected from the jet hole forms a shock wave after impacting the central cone. The annular groove or small concave walls increase the number of shock wave focusing times, thereby improving the efficiency of ignition and detonation. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a front view of a shock wave focusing detonation device with a central cone provided in this embodiment;

[0025] Figure 2 This is a perspective view of a shock wave focusing detonation device with a central cone provided in this embodiment;

[0026] Figure 3 This is a cross-sectional view of a shock wave focusing detonation device with a central cone provided in this embodiment;

[0027] Figure 4 This is a cross-sectional view of the central cone;

[0028] Figure 5 These are partial views of concave cavities in three different models;

[0029] Figure 6 These are the hydrogen mass fraction variation curves at monitoring points near the concave cavity; (a) Monitoring point A; (b) Monitoring point B; (c) Monitoring point C;

[0030] Figure 7 These are the pressure change curves at three monitoring points A, B, and C; (a) Monitoring point A; (b) Monitoring point B; (c) Monitoring point C;

[0031] Figure 8 It is the velocity vector diagram of the model with an annular grooved conical surface at t=17.7.

[0032] In the picture:

[0033] 1. Front section of main detonation tube; 2. Rear section of main detonation tube; 3. Flange; 4. Central cone; 5. Annular groove; 6. Jet hole. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0035] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0036] Example 1

[0037] This embodiment specifically provides a shock wave focusing detonation device with a central cone, such as... Figure 1-4 As shown, the internal space formed by the front section 1 of the main detonator tube and the central cone 4 has an axial air intake at the leading edge. After passing through a bend, the mixed gas enters the detonator tube along the tangent of the generatrix arc of the central cone 1. The pre-detonator tube that generates the hot jet is moved to the outer wall of the front section of the main detonator tube. The jet port 6 is separated from the air inlet. A continuous annular groove 5 is opened on the conical surface of the central cone 1, so that the hot jet is injected from the jet port 6 into the main detonator tube and collides with the central cone 1 to form a shock wave. By continuously focusing the shock wave on the annular groove 5, the efficiency of jet ignition and detonation is accelerated, the DDT distance is reduced, and a stable and reliable detonation wave is formed.

[0038] Specifically, the main detonation tube front section 1, the main detonation tube rear section 2 and the central cone 4 are concentrically distributed and the central cone 4 is located inside the main detonation tube front section 1. The main detonation tube front section 1 and the main detonation tube rear section 2 are connected by a flange 3. The outer surface of the main detonation tube front section 1 is provided with a jet hole 6 for injecting hot jets.

[0039] In this embodiment, the central cone 4 is a concave cone shape, with the generatrix being the radius. R An arc of 90~100mm, with a central angle of... θ The angle is 50°, and the height of the central cone 4 is... h It is 80mm. The horizontal distance between the top of the central vertebral body 4 and the proximal jet orifice 6 is 80mm. b It is 50mm.

[0040] In this embodiment, the central cone 4 has an annular groove 5 on its conical surface, so that the hot jet collides with the conical surface when it enters the detonation tube, and the annular groove 5 focuses the shock wave to increase the detonation efficiency. The annular groove 5 is continuously distributed from the top to the bottom of the central cone 4, and each groove is arc-shaped with a radius of curvature. r It is 2.0mm, and the central angle of the arc is... α The radius is 120°, and the centers of all five annular grooves are continuously distributed on the same concentric circle as the generatrix of the central cone four, with a radius of 120°. R 1 On a circle that is 99mm in diameter.

[0041] In this embodiment, the outer surface of the front section of the main detonation tube is a stepped cylinder, and the front section of the inner surface of the front section of the main detonation tube is an arc radius. r 1 The annular bend is 8mm, and the middle section of the inner surface of the front section of the main detonation tube has a radius of curvature that is tangent to the front section. r 2 The spherical surface is 28mm in diameter, and the rear section of the inner surface of the front section of the main detonation tube is a bevel tangent to the middle section. The jet holes are distributed on the middle section of the inner surface of the front section of the main detonation tube, and their diameter... d 1 The diameter is 8mm, and the outer surface of the front section of the main detonation tube at the corresponding position of the jet hole is provided with a diameter of 8mm. d 2 The circular boss is 16mm high relative to the outer surface. a The diameter is 12mm, and the jet holes and the circular boss are concentrically distributed and four are evenly distributed around the front section of the main detonation tube.

[0042] Its operating methods (detonation methods) include:

[0043] First, air is introduced axially and fuel gas is introduced radially into the mixing zone to mix them and form a high-pressure mixed fuel gas. The mixed gas flows axially into the ignition zone, while a hot jet is introduced from the hot jet pipe. The shock wave formed by the collision of the hot jet with the central cone is continuously focused on the annular groove to generate a stable and reliable detonation wave, which finally successfully ignites the mixed fuel gas.

[0044] Central vertebral wall focusing effect

[0045] Three models were used: one with a smooth central cone wall, one with an annular groove, and one with a wavy groove. Numerical simulation studies of filling and ignition were conducted on all three models under the same working conditions. Figure 5 The figures show partial views of the concave cavities in three different models. To compare the filling effects of the three models, three monitoring points were taken at equal intervals near the concave cavity during the numerical simulation. All models used a concave cavity with an 8mm inlet and a radius of 60mm. The radius of the concave wall in the latter two models was r=1.5mm.

[0046] To replicate identical inlet and environmental conditions, a pressure inlet was set at the annular jet inlet, with all parameters using temperature as the reference. ,pressure ; Set environmental conditions in the external area , All were premixed using hydrogen with an equivalence ratio of 1.0.

[0047] Figure 6 The hydrogen premixing effect at three monitoring points (A, B, and C) set in three models at different time points is illustrated. Figure 6(a) It can be seen that the wavy and smooth walls near the inlet have better filling effects, while the model with the annular groove wall has poor filling effects because the presence of sharp corners creates vortices inside the concave wall. For example... Figure 6 As shown in (b) and (c), dynamic monitoring at points B and C revealed that, due to the relatively large depth of the wavy wall, hydrogen could not be well premixed inside the concave wall, resulting in the worst overall mixing capacity of the wavy wall.

[0048] After premixing the hydrogen, we conducted hot ignition numerical simulation analyses using three different models. The operating conditions of the ignition zone were then set. =2000K, =0.606MPa was used to simulate the incoming flow of the hot jet. The same external conditions as the filling process were employed. During the combustion and detonation process, the pressure at points A, B, and C pre-set in the model was dynamically monitored again, and the change curves are shown below. Figure 7 As shown.

[0049] Depend on Figure 7 As shown in (a), just as the hot jet enters the main detonation tube from the pre-detonation tube, only the model with the annular grooved conical surface experiences a significant increase in pressure among the three models, reaching a peak at t=17.7. The pressure reaches a peak of 5.9 MPa. This is because there is a sharp leading edge on the conical surface of the annular groove. When the airflow passes through a small concave wall, the leading edge undergoes flow separation. Before flowing into the next small concave wall, it has to overcome the sharp obstacle, thus forming a vortex on the leeward side as well. This creates leading-edge vortices and trailing-edge vortices (such as...). Figure 8 (As shown). Therefore, within the model with the annular groove conical surface, the turbulent kinetic energy of the flow field is strong, exerting a positive feedback effect on the unburned gas and waves.

[0050] We can Figure 7 (b) and Figure 7 (c) It can be observed that the pressure at the three monitoring points of the annular groove cone surface model is significantly higher than that of the other two models. Figure 7 As shown in (c), although the pressure wave in the wavy groove cone model eventually reaches its peak value after continuous reflection and focusing, it is still slower and has a lower peak value than the model with annular groove cone surface. The former reaches its peak value at t=72.7. The peak pressure was 5.37 MPa, while the latter occurred as early as t=37.7. It reaches a peak pressure of 6.55 MPa.

[0051] Numerical simulation analysis shows that models with smooth central cone walls cannot successfully reflect and focus pressure waves for detonation, while models with wavy central cone walls have poor filling effects. Only models with annular grooves on the central cone meet the expected requirements in terms of both filling and ignition, thus improving the efficiency of ignition.

[0052] Example 2

[0053] In this embodiment, the conical surface of the central cone is provided with uniformly distributed small concave wall surfaces. The small concave wall surfaces are partial spherical surfaces that are uniformly distributed on the surface of the central cone. The radius of the sphere is 1.5~3.5mm and the solid angle of the sphere is 240°. The center of all the small concave wall surfaces is on a circle with the projection of the central cone axis onto the bottom surface as the center.

[0054] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the technical essence of the invention shall still fall within the protection scope of the technical solution of the present invention.

Claims

1. A shock wave focusing and detonation device with a central cone, characterized in that, It includes a front section of the main detonation tube, a rear section of the main detonation tube, and a central cone. The front and rear sections of the main detonation tube are concentrically distributed with the central cone, and the central cone is located inside the front section of the main detonation tube. The radius of the central cone gradually decreases from the front to the rear section of the main detonation tube. The mixed gas formed by air and fuel gas is axially introduced into the internal space formed by the front section of the main detonation tube and the central cone. After passing through a bend, the gas enters the ignition zone along the tangent of the generatrix arc of the central cone. The front and rear sections of the main detonation tube are connected by a flange. The outer surface of the front section of the main detonation tube is provided with jet holes for injecting hot jets. The central cone is concave conical, and the outer surface of the front section of the main detonation tube is a stepped cylinder. The front section of the inner surface of the front section of the main detonation tube has a circular arc radius. r 1 The annular bend is 6-8mm, and the middle section of the inner surface of the front section of the main detonation tube is a circular arc with a radius tangent to the front section. r 2 The spherical surface is 25~30mm in diameter, and the rear section of the inner surface of the front section of the main detonation tube is an inclined surface tangent to the middle section. The jet holes are distributed on the middle section of the inner surface of the front section of the main detonation tube; The central cone has an annular groove on its conical surface. The annular groove is continuously distributed from the top to the bottom of the central cone and is in the shape of an arc. The centers of all the annular grooves are continuously distributed on a circle concentric with the generatrix arc of the central cone.

2. The shock wave focusing detonation device with a central cone according to claim 1, characterized in that, The generatrix of the central cone is the radius. R An arc of 90~100mm, with a central angle of... θ The angle is 40°~50°, and the height of the central cone is... h It is 70~80mm.

3. The shock wave focusing detonation device with a central cone according to claim 2, characterized in that, The radius of the annular groove r The radius is 1.5~3.5mm, and the central angle of the arc is... α The angle is 120°, and the centers of all the annular grooves are continuously distributed on the same arc as the generatrix of the central cone, with a radius of 120°. R 1 On a circle of 97~99mm.

4. A shock wave focusing and detonation device with a central cone, characterized in that, It includes a front section of the main detonation tube, a rear section of the main detonation tube, and a central cone. The front and rear sections of the main detonation tube are concentrically distributed with the central cone, and the central cone is located inside the front section of the main detonation tube. The radius of the central cone gradually decreases from the front to the rear section of the main detonation tube. The mixed gas formed by air and fuel gas is axially introduced into the internal space formed by the front section of the main detonation tube and the central cone. After passing through a bend, the gas enters the ignition zone along the tangent of the generatrix arc of the central cone. The front and rear sections of the main detonation tube are connected by a flange. The outer surface of the front section of the main detonation tube is provided with jet holes for injecting hot jets. The central cone is concave conical, and the outer surface of the front section of the main detonation tube is a stepped cylinder. The front section of the inner surface of the front section of the main detonation tube has a circular arc radius. r 1 The annular bend is 6-8mm, and the middle section of the inner surface of the front section of the main detonation tube is a circular arc with a radius tangent to the front section. r 2 The spherical surface is 25~30mm in diameter, and the rear section of the inner surface of the front section of the main detonation tube is an inclined surface tangent to the middle section. The jet holes are distributed on the middle section of the inner surface of the front section of the main detonation tube; The central cone has uniformly distributed small concave walls on its conical surface. The small concave walls are partial spherical surfaces that are uniformly distributed on the surface of the central cone. The centers of all the small concave walls are on a circle centered on the projection of the central cone axis onto the bottom surface.

5. A shock wave focusing detonation device with a central cone according to claim 4, characterized in that, The concave wall has a spherical radius of 1.5~3.5mm and a spherical solid angle of 240°.

6. A shock wave focusing detonation device with a central cone according to claim 5, characterized in that, The diameter of the jet orifice d 1 The diameter is 6~10mm, and the outer surface of the front section of the main detonation tube at the corresponding position of the jet hole is provided with a diameter of 6~10mm. d 2 The boss is a circular boss with a diameter of 12-18mm, and the height of the circular boss relative to the outer surface is... a The diameter is 10~15mm, and the jet holes and the circular boss are concentrically distributed and 4~8 are evenly distributed around the front section of the main detonation tube.

7. The operating method of a shock wave focusing detonation device with a central cone according to any one of claims 1-6, characterized in that, The operation method includes: Step 1: First, fix it to the ignition end of the engine to be ignited, and connect the gas intake pipe and high-pressure air intake pipe of the front mixing zone to the hot jet pipe of the ignition zone. The gas is introduced radially and the air is introduced axially. Step 2: After installation, air and gas are introduced to mix them in the mixing zone. The mixed gas flows axially into the ignition zone, while a hot jet is introduced from the hot jet pipe. The shock wave formed by the collision of the hot jet with the central cone is continuously focused on the annular groove or small concave wall, generating a stable and reliable detonation wave, and finally successfully igniting the mixed gas.

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