Fuel support plate injection device of external injection type oblique detonation engine and engine

Abstract

The invention provides a fuel support plate injection device of an external injection type oblique detonation engine, which comprises a support plate arranged in front of a first-stage compression shock wave of a two-dimensional air inlet channel, and the support plate comprises a front edge passivated wedge body close to the upstream of incoming flow gas, a middle equal straight section cuboid, and a rear edge passivated wedge body close to the downstream of the incoming flow gas; a first cooling channel is arranged at the front part of the support plate, and a second cooling channel is arranged at the rear part of the support plate; the front edge of the supporting plate is provided with an injection slit directly connected with the first cooling channel, and the rear edge of the supporting plate is provided with a plurality of injection holes directly connected with the second cooling channel.

Description

Technical Field

[0001] The invention is designed based on the field of oblique detonation engines, and in particular relates to a fuel support plate injection device of an external injection type oblique detonation engine and an engine. Background Art

[0002] The oblique detonation engine has the advantages of compact structure and high combustion efficiency, and shows great application potential in the field of hypersonic propulsion. During its operation, in order to ensure that the fuel and air are fully mixed, an intrusive support plate is usually used for fuel injection.

[0003] However, when the flight Ma exceeds 8, the total temperature of the incoming flow will exceed 3000K. At this temperature, the support plate will be subjected to an extremely high heat load, and this temperature is also far beyond the ignition point of hydrogen fuel. Active cooling must be used to cool and protect the support plate and fuel, while avoiding premature combustion of the fuel.

[0004] Patent 201911265992.X proposes a combustion chamber extension support plate that is not specially designed for the problems of premature combustion and heat deposition. Patent 201410766649.4 proposes a "thermal protection method for the front edge nose cone of a porous medium injection support plate". This method sprays low-temperature fuel from the front edge of the support plate to provide thermal protection for the part of the front edge that is prone to ablation, but its shortcoming is that it does not consider the risk of premature combustion of the fuel at the support plate.

[0005] As an important component of the oblique detonation engine, the support plate plays a key role in the fuel injection and mixing process. However, during its operation, the temperature of the front end of the support plate is extremely high, and it is subjected to a huge heat load, which makes it easy to ablate, and there is a risk of premature combustion of the fuel. Therefore, active cooling measures must be used to protect the support plate and the fuel. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a fuel support plate injection device for an external injection oblique detonation engine, which can avoid the problems of premature combustion of hydrogen fuel and thermal deposition of the support plate in the injection device.

[0007] In order to solve the above problems, the present invention provides a fuel support plate injection device for an external injection oblique detonation engine, comprising a support plate installed in front of the first-stage compression shock wave of a binary inlet, the support plate comprising a wedge body with a blunt leading edge close to the upstream of the incoming gas flow, a straight rectangular parallelepiped in the middle, and a wedge body with a blunt trailing edge downstream of the incoming gas flow;

[0008] A first cooling channel is provided at the front of the support plate, and a second cooling channel is provided at the rear of the support plate;

[0009] The front edge of the support plate is provided with an injection slit directly connected to the first cooling channel, and the rear edge of the support plate is provided with a plurality of injection holes directly connected to the second cooling channel.

[0010] In some embodiments, the length of the wedge whose leading edge is blunted near the upstream of the incoming gas flow is 30 mm, and the length of the wedge whose trailing edge is blunted near the downstream of the incoming gas flow is 30 mm.

[0011] In some embodiments, the blunting radius of the leading edge of the support plate is 1 mm, and the blunting radius of the trailing edge of the support plate is 1 mm.

[0012] In some embodiments, the straight section of the rectangular parallelepiped in the middle is 20 mm long and 12 mm high.

[0013] In some embodiments, the cross section of the spray hole is rectangular, and two upper and lower opposite planes in the spray hole are parallel.

[0014] In some embodiments, the nozzle hole has a width of 1 mm and a depth of 4 mm.

[0015] In some embodiments, the interval between each nozzle hole is 20 mm.

[0016] In some embodiments, the width of the injection slit is 1 mm, and the upper and lower relative planes of the injection slit are parallel.

[0017] The present invention also provides an external injection type oblique detonation engine, comprising the above-mentioned fuel support plate injection device.

[0018] In some of the embodiments, a straight external injection oblique detonation engine combustion chamber and a gradually expanding external injection oblique detonation engine nozzle are sequentially arranged downstream of the secondary air inlet.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1) By injecting inert cooling gas in reverse, the bow shock wave induced by the support plate is separated from the leading edge of the support plate, and a low-temperature gas reflow zone is formed at the leading edge of the support plate, which effectively reduces the heat load at the leading edge of the support plate;

[0021] 2) Under the action of high-speed incoming flow, the inert cooling gas forms an air film on the surface of the support plate, providing effective thermal protection for the support plate wall;

[0022] 3) By arranging cooling channels for fuel and inert cooling gas inside the support plate, the heat of the support plate wall is further removed;

[0023] 4) Under the action of the incoming flow, the inert cooling gas is concentrated and distributed around the hydrogen gas ejected from the nozzles at the rear of the support plate, isolating it from the high-temperature air, effectively avoiding the problem of premature combustion of the fuel;

[0024] 5) The bow shock wave generated by the reverse injection reduces the speed of the incoming flow, prolongs the residence time of the fuel, improves the mixing efficiency, reduces the number of support plates required for injection, and greatly reduces the total pressure loss caused by the injection device. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the support plate installation structure in the present invention;

[0026] Figure 2 It is a three-view drawing of the support plate in the present invention;

[0027] Figure 3 It is a schematic diagram of the internal structure of the support plate in the present invention;

[0028] Figure 4 It is a schematic diagram of the thermal protection principle in the present invention;

[0029] Figure 5 It is a cloud diagram of H2O mass fraction distribution in the numerical simulation flow field of the present invention;

[0030] Figure 6 It is a temperature cloud diagram of a stationary oblique detonation wave in a combustion chamber of the present invention in numerical simulation. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.

[0032] Reference Figure 1-Figure 6 As shown, this embodiment provides a fuel support plate injection device for an external injection oblique detonation engine, comprising a support plate 4 installed in front of the first-stage compression shock wave of a binary inlet duct, wherein the support plate 4 comprises a wedge 42 with a blunt leading edge close to the upstream of the incoming gas flow, a straight section rectangular parallelepiped 43 in the middle, and a wedge 44 with a blunt trailing edge downstream of the incoming gas flow;

[0033] A first cooling channel 46 is provided at the front of the support plate, and a second cooling channel 47 is provided at the rear of the support plate;

[0034] The front edge of the support plate 4 is provided with an injection slit 41 directly connected to the first cooling channel 46 , and the rear edge of the support plate 4 is provided with a plurality of injection holes 45 directly connected to the second cooling channel 47 .

[0035] like Figure 4 As shown, when the support plate injection device of this embodiment is used, the inert cooling gas is first

[0036] It first flows through the cooling channel 46 to reduce the temperature of the support plate, and then is ejected through the slit 41 at the front edge of the support plate, separating the bow shock wave induced by the support plate from the front edge of the support plate, and forming a low-temperature reflow zone at the front edge of the support plate to reduce the heat load at the front edge of the support plate. Under the action of the incoming flow, the inert cooling gas flows along the wall of the support plate body 4, forming a layer of low-temperature gas film on the wall, which effectively protects the support plate body 4 from heat. The spray hole 45 at the rear edge of the support plate sprays fuel backward along the direction of the incoming gas flow, and the wedge 44 at the rear half of the support plate can make the inert gas flow backward along the surface of the support plate, covering the surface of the fuel ejected from the spray hole 45, isolating the fuel from the high-temperature air behind the shock wave, and avoiding premature combustion of the fuel.

[0037] The injection method along the flow field direction can avoid the shock wave generated at the nozzle hole due to the injection flow, and reduce the total pressure loss caused by the injection. The bow shock wave generated by the support plate and the incoming flow will significantly reduce the speed of the incoming air, create an environment conducive to fuel mixing, extend the residence time of the fuel, and improve the fuel mixing efficiency. Compared with the traditional support plate injection method, the number of mixing support plates can be reduced, greatly reducing the total pressure loss caused by the injection device.

[0038] The injection slit 41 uses N2 with a total temperature of 300K and a total pressure of 0.2MPa for injection; the injection hole 45 uses H2 with a total temperature of 300K and a total pressure of 3MPa for injection.

[0039] In order to reduce the total pressure loss and the leading edge temperature when the incoming gas passes through the support plate, in this embodiment, the length of the wedge 42 with the leading edge passivated near the upstream of the incoming gas is 30 mm, and the leading edge passivation radius is 1 mm; the length of the straight section cuboid 43 in the middle is 20 mm, and the height is 12 mm; the length of the wedge 44 with the trailing edge passivated at the downstream of the incoming gas is 30 mm, and the trailing edge passivation radius is 1 mm. The width of the reverse injection slit 41 at the front end of the support plate 4 is 1 mm, and the upper and lower relative planes of the injection slit 41 are parallel.

[0040] Through the above arrangement, the bow shock wave at the leading edge of the support plate can be pushed away as a whole, reducing the temperature of the leading edge of the support plate and reducing the heat load; and a cooling air film is formed on the downstream support plate wall, thereby achieving good thermal protection performance. In addition, since the bow shock wave strengthened by the reverse injection will greatly reduce the incoming flow velocity, extend the mixing time of the fuel in the intake duct, and greatly improve the mixing efficiency, the injection requirements of the engine can be met with one support plate, significantly reducing the total pressure loss caused by the injection device.

[0041] Furthermore, in this embodiment, the cross section of the spray hole 45 is rectangular, and two upper and lower opposite planes in the spray hole 45 are parallel. The width of the hydrogen spray hole 45 at the rear end of the support plate 4 is 1 mm, the length is 4 mm, and each spray hole is spaced 20 mm apart.

[0042] Through the above-mentioned arrangement, the injection method along the incoming flow direction from the trailing edge of the support plate can make the inert cooling gas film at the upstream support plate wall cover the fuel surface, and the wall fuel burns in advance; secondly, the injection method along the flow direction can avoid the bow shock wave caused by the interaction between the jet and the incoming flow, thereby reducing the total pressure loss; finally, injecting the fuel through the nozzle hole can increase the total injection pressure, thereby improving the fuel injection efficiency.

[0043] Example 2

[0044] This embodiment provides an external injection oblique detonation engine including the above-mentioned fuel support plate injection device, wherein a straight external injection oblique detonation engine combustion chamber 2 and a gradually expanding external injection oblique detonation engine nozzle 3 are sequentially arranged downstream of the secondary air intake 1. The binary air intake 1 is used to perform two-stage compression on the incoming air flow and deflect its flow direction, and the fuel and air are mixed in the air intake; the straight combustion chamber 2 is used to induce the formation of a detonation wave; and the gradually expanding nozzle 3 is used to form thrust. The oblique detonation wave stationed in the combustion chamber can be stably induced and continuously generated thrust.

[0045] The above is only a preferred specific implementation of the present invention, but the design concept of the present invention is not limited to this. Any technician familiar with the technical field uses this concept to make non-substantial changes to the present invention within the technical scope disclosed by the present invention, which is an infringement of the protection scope of the present invention.

Claims

1. A fuel support plate injection device for an external injection oblique detonation engine, It is characterized in that It includes a support plate installed in front of the first-stage compression shock wave of the binary inlet, the support plate includes a wedge body with a blunt leading edge close to the upstream of the incoming gas flow, a straight rectangular parallelepiped in the middle, and a wedge body with a blunt trailing edge downstream of the incoming gas flow; A first cooling channel is provided at the front of the support plate, and a second cooling channel is provided at the rear of the support plate; The front edge of the support plate is provided with an injection slit directly connected to the first cooling channel, and the rear edge of the support plate is provided with a plurality of injection holes directly connected to the second cooling channel.

2. The fuel support plate injection device of the external injection oblique detonation engine according to claim 1, It is characterized in that The length of the wedge whose leading edge is passivated near the upstream of the incoming gas flow is 30 mm, and the length of the wedge whose trailing edge is passivated near the downstream of the incoming gas flow is 30 mm.

3. The fuel support plate injection device of the external injection oblique detonation engine according to claim 2, It is characterized in that The front edge blunting radius of the support plate is 1 mm, and the rear edge blunting radius of the support plate is 1 mm.

4. The fuel support plate injection device of the external injection oblique detonation engine according to claim 1, It is characterized in that The length of the straight section in the middle is 20 mm and the height is 12 mm.

5. The fuel support plate injection device of the external injection oblique detonation engine according to claim 1, It is characterized in that The cross section of the spray hole is rectangular, and two upper and lower opposite planes in the spray hole are parallel.

6. The fuel support plate injection device of the external injection oblique detonation engine according to claim 5, It is characterized in that The width of the spray hole is 1 mm and the depth is 4 mm.

7. The fuel support plate injection device of the external injection oblique detonation engine according to claim 5, It is characterized in that The interval between each spray hole is 20 mm.

8. The fuel support plate injection device of the external injection oblique detonation engine according to claim 1, It is characterized in that The width of the injection slit is 1 mm, and the upper and lower relative planes of the injection slit are parallel.

9. An external injection oblique detonation engine, It is characterized in that It comprises the fuel support plate injection device as described in any one of claims 1-9.

10. The external injection oblique detonation engine according to claim 9, It is characterized in that An iso-straight external-injection oblique-detonation engine combustion chamber and a gradually-expanding external-injection oblique-detonation engine nozzle are sequentially arranged downstream of the secondary air inlet duct.

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