A supersonic flow enhanced mixing device, mixing method and engine thereof

Abstract

The present invention belongs to the field of aerospace enhanced mixing devices, and specifically relates to a supersonic flow enhanced mixing device, a mixing method and an engine thereof. The supersonic flow enhanced mixing device includes a partition plate and a lower side wall plate, wherein the lower side wall plate includes a flat plate and a convex curvature plate connected to each other; the partition plate and the flat plate are parallel to each other, and the space between the partition plate and the flat plate is used for the flow of airflow I flowing from the flat plate to the convex curvature plate, and the end of the partition plate away from the flat plate is used for the flow of airflow II parallel to the flow direction of the airflow I. That is, the present invention can achieve an enhanced mixing effect by cleverly utilizing the inherent upper and lower wall structure devices of the flow channel and adopting slight structural optimization, without the need for external excitation energy and the introduction of additional physical structural devices, thus overcoming the defects of large flow resistance and flow loss, and having a relatively wide range of applicability.

Description

Technical Field

[0001] The invention belongs to an enhanced mixing device in the field of aerospace, and in particular relates to a supersonic flow enhanced mixing device, a mixing method and an engine thereof. Background Art

[0002] The mixed layer flow formed by the high-speed gas and air meeting behind the partition is widely present in the scramjet engine power system, in which the efficient mixing of gas and air is crucial for the efficient operation of the engine system. However, for the scramjet engine power system, the engine operates in a supersonic state, and the mixing of the supersonic air flow and the high-speed gas flow is inhibited by the flow compression effect, resulting in efficient mixed combustion and its difficulty. In addition, due to the limitation of the size of the aircraft, the length of the combustion chamber is only a few meters, and the residence time of the high-speed airflow in it is in the millisecond level. Efficient gas-gas mixing in a limited space is extremely challenging.

[0003] In order to promote efficient mixing of gas and air, domestic and foreign scholars have proposed a series of enhanced mixing schemes. Based on the principle of enhanced mixing, it can be divided into two types: passive and active. The flow control method of passive mixing enhancement is achieved by installing some fixed devices in the flow field, or by changing the shape parameters of the structure to change the stability characteristics of the shear flow to achieve enhanced mixing. The literature (Abolfadl MA, Metwally MA, El-Messiry AM, et.al. Experimental Investigation of Lobed Mixer Performance[J]. Journal of Propulsion and Power, 2001, 17: 1109-1116.) proposed a scheme to introduce a vortex generator into the partition plate to enhance flow mixing. After the flow vortex structure generated by the vortex generator falls off to the mixing area, it interacts with the flow field structure of the mixed flow, thereby stimulating the three-dimensional instability characteristics of the flow to achieve enhanced mixing. Although the device has a significant effect in low-speed flow, it has not yet been applied under supersonic conditions. At the same time, the study also pointed out that the flow loss caused by the introduction of the material structure device cannot be ignored. The literature (PJ Lu, KC Wu, On the shock enhancement of confined supersonic mixing flows, A 3, 3046 (1991)) studied the introduction of shock wave structures into the flow field and the realization of enhanced mixing through the interaction of shock wave mixing layers, and achieved certain results. However, the study also pointed out that since shock waves are compression waves, they also bring significant flow losses.

[0004] The active enhanced mixing scheme requires the introduction of external energy into the flow field to achieve flow control. According to the control purpose that the flow needs to achieve, the external actuator can input an excitation of a specific frequency and amplitude. The advantage of active control technology is that the position and parameters of the excitation are easy to control. The literature (Wang Peng, Shen Chi-Bing, Mixing enhancement for supersonic mixing layer by using plasma synthetic jet, Acta Physica Sinica, 68, 174701 (2019)) proposed a measure of active excitation using synthetic jets to study its effect on supersonic jet mixing. They attached a plasma actuator array at the trailing edge of the partition of the supersonic incoming flow, about 15 mm away from the tail end of the partition, to achieve disturbance of the upper airflow, and the five actuators worked in series discharge mode. The disturbance of the mixing layer flow field is achieved through plasma discharge excitation, thereby effectively exciting the large-scale structure of the mixing layer. However, due to the complex structure of the active mixing device, it is not easy to install in the supersonic flow channel, and the actual operation is relatively difficult.

[0005] It can be found that the existing passive enhancement hybrid technology has large flow losses, and the active enhancement hybrid technology has the disadvantage of being difficult to apply in engineering. There is an urgent need to propose a new type of hybrid enhancement scheme to support the realization of efficient propulsion of aerospace power systems. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a supersonic flow enhancement mixing device, a mixing method and an engine thereof which overcome the defects of existing mixing schemes such as large flow resistance and flow loss and have good mixing effect.

[0007] The present invention provides a supersonic flow enhancement mixing device, comprising a partition plate and a lower side wall plate, wherein the lower side wall plate comprises a flat plate and a convex curvature plate connected to each other;

[0008] The partition plate and the flat plate are parallel to each other, and airflow I flowing from the flat plate to the convex curvature plate flows between the partition plate and the flat plate. An end of the partition plate away from the flat plate is used to flow airflow II parallel to the flow direction of airflow I.

[0009] Furthermore, the downstream end of the partition plate is arranged within the projection range of the flat plate.

[0010] Furthermore, the curvature of the convex curvature plate is less than 120 mm.

[0011] Furthermore, the curvature of the convex curvature plate is 100 mm.

[0012] Furthermore, the sector angle of the convex curvature plate is less than 30°.

[0013] Furthermore, the sector angle of the convex curvature plate is 20°.

[0014] Furthermore, the flat plate and the convex curvature plate are formed together.

[0015] Furthermore, the flat plate and the convex curvature plate are made of alloy spring steel.

[0016] The present invention also provides a supersonic flow enhanced mixing method, using the above-mentioned supersonic flow enhanced mixing device, comprising the following steps:

[0017] Airflow I flows from between the partition plate and the flat plate in a direction from the flat plate to the convex curvature plate, and airflow II flows from one end of the partition plate away from the flat plate in a direction parallel to airflow I. Airflow I and airflow II meet at the downstream of the partition plate to form a mixed layer.

[0018] When airflow I flows to the convex curvature plate, the flow channel is in an expansion state, and a series of expansion wave systems are generated on the convex curvature plate. The expansion wave system is injected into the mixing layer, and the expansion wave system interacts with the mixing layer. The injection of the expansion wave of the expansion wave system makes the vorticity distribution range of the vortex structure in the mixing layer expand and the vortex structure becomes more fragmented, and the corresponding mixing layer area is increased in the lateral height range.

[0019] When airflow I flows to the convex curvature plate, the flow passage is accelerated so that the velocity of airflow I is faster than that of airflow II, which makes the flow unstable, enhances the three-dimensional characteristics of the flow field, and strengthens the mixing effect of airflow I and airflow II.

[0020] The present invention also provides an engine, comprising the above-mentioned supersonic flow enhancement mixing device.

[0021] The beneficial effect of the present invention is that the supersonic flow enhanced mixing device provided by the present invention, on the one hand, utilizes the convex curvature plate to generate an expansion wave system to interact with the mixing layer, promoting mixing during the intake process of airflow I and airflow II, and on the other hand, utilizes the flow passage acceleration of the convex curvature plate to make airflow I and airflow II have a speed difference, further enhancing the mixing effect of airflow I and airflow II. That is, by cleverly utilizing the inherent upper and lower wall structure devices of the flow passage and adopting slight structural optimization, the enhanced mixing effect can be achieved, no external excitation energy is required, and no additional physical structure device is required, thus overcoming the defects of large flow resistance and flow loss, and having a relatively wide range of applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Attached Figure 1 Schematic diagram of the structure of the supersonic flow enhanced mixing device;

[0023] Attached Figure 2 This is the front view of the supersonic flow enhancement mixing device.

[0024] In the figure, 1-airflow I; 2-airflow II; 3-partition plate; 4-flat plate; 5-convex curvature plate; 6-flow channel I; 7-flow channel II; 8-inlet channel; 9-mixing layer; 10-expansion wave system. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] 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 position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0027] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0028] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0030] As attached Figure 1 -Attached Figure 2As shown, the present invention provides a supersonic flow enhancement mixing device, comprising a partition plate 3 and a lower side wall plate, wherein the lower side wall plate comprises a flat plate 4 and a convex curvature plate 5 connected to each other, that is, the downstream end of the flat plate 4 is connected to the upstream end of the convex curvature plate 5;

[0031] The partition plate 3 and the flat plate 4 are parallel to each other, and the space between the partition plate 3 and the flat plate 4 is used for the flow of airflow I1 flowing from the flat plate 4 to the convex curvature plate 5, that is, the space between the partition plate 3 and the flat plate 4 is used to form a flow channel I6 for the flow of airflow I1, that is, there is also a side wall (not shown in the figure) between the partition plate 3 and the flat plate 4, and the partition plate 3, the flat plate 4 and the two side walls form the flow channel I6. The end of the partition plate 3 away from the flat plate 4 is used for the flow of airflow II2 parallel to the flow direction of the airflow I1, that is, the end of the partition plate 3 away from the flat plate 4 is the flow channel II7, and the end of the partition plate 3 away from the flat plate 4 is also provided with an upper side wall plate (not shown in the figure), and there is also a side wall (not shown in the figure) between the upper side wall plate and the partition plate 3, and the upper side wall plate, the partition plate 3 and the two side walls form the flow channel II7. The flow channel I6 and the flow channel II7 are interconnected at the downstream end of the partition plate 3 to form an air inlet channel 8 with a larger size, that is, the flow channel is in an expanded state when the flow channel I6 reaches the air inlet channel 8, and the flow channel is also in an expanded state when the flow channel II7 reaches the air inlet channel 8.

[0032] The airflow I1 and the airflow II2 are different gases, which can enhance the mixing of the airflow I1 and the airflow II2. Preferably, the airflow I1 can be a supersonic fuel-rich combustion gas, and the airflow II2 can be incoming air.

[0033] The supersonic flow enhancement mixing device provided by the present invention can enhance the mixing effect of fuel gas and air during the intake process. That is, using the supersonic flow enhancement mixing device, a supersonic flow enhancement mixing method can be performed, comprising the following steps:

[0034] The airflow I1 flows from the flow channel I6 between the partition plate 3 and the flat plate 4 along the direction from the flat plate 4 to the convex curvature plate 5, and the airflow II2 flows from the flow channel II7 at the end of the partition plate 3 away from the flat plate 4 in a direction parallel to the airflow I1. The fluid below the airflow I1 flows from the bottom of the partition plate 3 to the downstream end of the partition plate 3, and the fluid above the airflow II2 flows from the top of the partition plate 3 to the downstream end of the partition plate 3. The two parts of the fluid of the airflow I1 and the airflow II2 meet at the downstream of the partition plate 3 to form a mixed layer 9, and the mixed layer 9 extends downstream for a certain distance at the middle of the air inlet 8;

[0035] When the airflow I1 flows to the convex curvature plate 5, due to the expansion state of the flow channel, a series of expansion wave systems 10 are generated on the convex curvature plate 5, and the expansion wave system 10 is injected into the mixing layer 9. The expansion wave system 10 interacts with the mixing layer 9. The injection of the expansion wave of the expansion wave system 10 expands the vorticity distribution range of the vortex structure in the mixing layer 9 and makes the vortex structure more fragmented, and the corresponding mixing layer 9 area is increased in the lateral height range;

[0036] When airflow I1 flows to the convex curvature plate 5, due to the presence of the expansion channel, the airflow I1 passing through is accelerated, and its flow velocity is faster than that of airflow II2, which further destabilizes the flow, significantly enhances the three-dimensional characteristics of the flow field, and strengthens the mixing effect of airflow I1 and airflow II2. That is, the convex curvature plate 5 will not increase the flow resistance and cause flow loss, but will increase the flow velocity.

[0037] The supersonic flow enhanced mixing device provided by the present invention, on the one hand, utilizes the convex curvature plate 5 to generate an expansion wave system 10 to interact with the mixing layer 9, promoting mixing during the intake process of the airflow I1 and the airflow II2, and on the other hand, utilizes the flow passage acceleration of the convex curvature plate 5 to make the airflow I1 and the airflow II2 have a speed difference, further enhancing the mixing effect of the airflow I1 and the airflow II2. That is, by cleverly utilizing the inherent upper and lower wall structure devices of the flow passage and adopting slight structural optimization, the enhanced mixing effect can be achieved, without the need for additional excitation energy, and without the need for additional introduction of physical structure devices, the defects of large flow resistance and flow loss are overcome, and it has a relatively wide range of applicability.

[0038] In addition, the Chinese invention patent application "CN109139267A-Supersonic flow mixing device" proposes a supersonic flow mixing device, which uses the concave surface of the partition plate in the middle of the flow channel to generate Görtler vortices to promote flow instability, thereby realizing a supersonic flow mixing device. Different from the present invention, the application uses the middle partition plate to induce the generation of Görtler vortices, and the Görtler vortices interact with the mixed flow vortex structure to achieve mixing enhancement, while in the present invention, the expansion wave system structure is generated by using the convex curvature plate part of the lower wall, and the expansion wave interacts with the mixing layer flow to achieve enhanced mixing.

[0039] In one of the embodiments, the downstream end of the partition plate 3 is arranged within the projection range of the flat plate 4, that is, the downstream end of the partition plate 3 is shorter than the downstream end of the flat plate 4, which can avoid the expansion wave system 10 colliding with the lower end surface of the partition plate 3 and wasting the expansion wave system 10.

[0040] In one embodiment, in order to enable the expansion wave system 10 generated when the airflow I1 flows through a part of the convex curvature plate 5 to interact with the mixing layer 9, the curvature R of the convex curvature plate 5 is less than 120 mm. Preferably, the curvature R of the convex curvature plate 5 is 100 mm.

[0041] In one embodiment, in order to make the expansion wave system 10 induced by the fan angle of the selected convex curvature plate 5 cover the transition region of the mixing layer 9 (i.e., the flow region before the supersonic mixing layer flow enters the full turbulent region), the fan angle α of the convex curvature plate 5 is less than 30°. Preferably, the fan angle α of the convex curvature plate 5 is 20°. In this way, it can be ensured that the expansion wave system 10 can interact with the mixing layer 9 in the entire transition region to promote mixing.

[0042] In one embodiment, in order to ensure that the structure of the lower side wall plate is reliable and the surface is smooth, the flat plate 4 and the convex curvature plate 5 are formed together.

[0043] In one embodiment, the flat plate 4 and the convex curvature plate 5 are made of alloy spring steel, which has good fatigue resistance.

[0044] The present invention also provides an engine, comprising the above-mentioned supersonic flow enhancement mixing device.

[0045] The above is only an embodiment and does not limit the present invention in any way. Any person skilled in the art can use the above disclosed technical contents to make many possible changes, modifications or modifications to the technical solutions of the present invention into equivalent embodiments of equivalent changes without departing from the scope of the technical solutions of the present invention. Therefore, any simple modification, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the scope of protection of the technical solutions of the present invention.

Claims

1. A supersonic flow intensification mixing device, characterized in that: It comprises a partition plate (3) and a lower side wall plate, wherein the lower side wall plate comprises a flat plate (4) and a convex curvature plate (5) connected to each other; The partition plate (3) and the flat plate (4) are parallel to each other, and an airflow I (1) flowing from the flat plate (4) to the convex curvature plate (5) flows between the partition plate (3) and the flat plate (4), and an airflow II (2) parallel to the flow direction of the airflow I (1) flows at one end of the partition plate (3) away from the flat plate (4); The curvature of the convex curvature plate (5) is less than 120 mm, and the sector angle of the convex curvature plate (5) is less than 30°; The downstream end of the partition plate (3) is arranged within the projection range of the flat plate (4).

2. The supersonic flow intensification mixing device according to claim 1, characterized in that: The curvature of the convex curvature plate (5) is 100 mm.

3. The supersonic flow intensification mixing device according to claim 1, characterized in that: The sector angle of the convex curvature plate (5) is 20°.

4. The supersonic flow intensification mixing device according to any one of claims 1 to 3, characterized in that: The flat plate (4) and the convex curvature plate (5) are formed together.

5. The supersonic flow intensification mixing device according to any one of claims 1 to 3, characterized in that: The flat plate (4) and the convex curvature plate (5) are made of alloy spring steel.

6. A supersonic flow enhanced mixing method, characterized in that: Using the supersonic flow enhancement mixing device as described in any one of claims 1 to 5 comprises the following steps: The airflow I (1) flows from between the partition plate (3) and the flat plate (4) in a direction from the flat plate (4) to the convex curvature plate (5), and the airflow II (2) flows from the end of the partition plate (3) away from the flat plate (4) in a direction parallel to the airflow I (1). The airflow I (1) and the airflow II (2) meet at a downstream of the partition plate (3) to form a mixing layer (9); When the airflow I (1) flows to the convex curvature plate (5), the flow channel is in an expanded state, and a series of expansion wave systems (10) are generated on the convex curvature plate (5). The expansion wave system (10) is injected into the mixing layer (9). The expansion wave system (10) interacts with the mixing layer (9). The injection of the expansion wave of the expansion wave system (10) causes the vorticity distribution range of the vortex structure in the mixing layer (9) to expand and the vortex structure to become more fragmented, and the corresponding mixing layer (9) area is increased within the lateral height range. When the airflow I (1) flows to the convex curvature plate (5), due to the presence of the expansion channel, the airflow I (1) passing through is accelerated and its flow velocity is faster than that of the airflow II (2), which causes the flow to become unstable, enhances the three-dimensional characteristics of the flow field, and strengthens the mixing effect of the airflow I (1) and the airflow II (2).

7. An engine, characterized in that: It comprises the supersonic flow intensification mixing device as described in any one of claims 1 to 5.

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