A rotating grid type rear duct ejector for a variable cycle engine

Abstract

A rotating grille-type rear duct ejector for a variable cycle engine can effectively enhance the mixing of the inner and outer duct airflows in the low bypass ratio mode of the variable cycle engine, improve the mixing efficiency, and thus improve the combustion efficiency of the afterburner. The rotating grille-type rear duct ejector uses 32 grilles located at the outer duct outlet to rotate and adjust the area. The outer duct airflow passes through the gaps between the grilles. When the airflow passes through the grilles, due to the special structure of the grilles, a high-intensity vortex will be generated, and each grille has a certain inclination angle. The contained airflow can be well diffused to the entire mixing section, so that the inner and outer duct airflows are mixed evenly to a greater extent, and the mixing distance is greatly reduced. The trapezoidal grille set on the grille of the present invention has the ability to drain, can effectively reduce the total pressure loss, improve the mixing efficiency, and ensure the stable combustion of the afterburner and good afterburner inlet conditions.

Description

Technical Field

[0001] The invention relates to the technical field of variable cycle engine structure design, and in particular to a rotary grid type rear duct ejector for a variable cycle engine. Background Art

[0002] As the power unit of the next generation of fighter jets, the variable cycle engine combines the low fuel consumption of a large bypass ratio turbofan engine under subsonic flight conditions and the high thrust of a turbojet engine under supersonic conditions. It adjusts the engine's thermal cycle parameters by changing the geometry, size or position of some adjustable components of the engine, so that the engine has suitable thermal cycle parameters under various operating conditions, greatly improving the aircraft performance.

[0003] The rear duct ejector is one of the important adjustable components of the variable cycle engine to change the thermal cycle parameters. It is similar to a variable area mixer. It adjusts the flow rate of the inner and outer ducts by changing the area ratio of the inner and outer ducts of the engine, and matches with the mode selection valve and the front duct ejector to achieve the purpose of adjusting the thermal cycle parameters of the variable cycle engine.

[0004] The gas in the inner and outer ducts is mixed after passing through the rear duct ejector. The mixing effect will greatly affect the combustion efficiency of the afterburner and thus the thrust performance of the engine. In the traditional translational and rotational area adjustment scheme, the mixing between the inner and outer duct airflows only relies on the shearing effect of one airflow contact surface, and its mixing effect is poor.

[0005] In recent years, research on variable area rear duct ejectors has been carried out both at home and abroad, but most of the adjustment schemes only consider the completion area adjustment and do not achieve high thermal mixing efficiency. The present invention adopts a simple area adjustment method with small total pressure loss and high thermal mixing efficiency. Summary of the invention

[0006] The purpose of the present invention is to solve the above-mentioned problems in the prior art, and to provide a rotating grille type rear duct ejector for a variable cycle engine. Compared with the existing rear duct ejector area adjustment scheme, the present invention uses 32 grilles located at the outer duct outlet to rotate and adjust the area. The shape of the grille is set to a trapezoidal block inclined at 45 degrees. When the outer duct airflow flows through the grille, it is guided by the two sides of the grille and passes through the gaps between the grilles. When the airflow passes through the grille, a vortex of a certain intensity will be generated due to the special structure of the grille. Each grille has a certain inclination angle, and the internal airflow can be well diffused to the entire mixing section. When the outer duct airflow flows into the mixing section, it is violently mixed. The inner and outer duct airflows form a large-scale mixing area at the rear end of the grille, which makes the inner and outer duct airflows mixed evenly to a large extent, greatly reducing the mixing distance.

[0007] In order to achieve the above object, the present invention adopts the following technical scheme:

[0008] A rotating grille-type rear duct ejector for a variable cycle engine comprises a grille, an actuating connecting rod, a fixing ring and a hydraulic actuator; the grille is evenly distributed at the duct outlet of the variable cycle engine, the grille is arranged in a trapezoidal shape, and the side with a smaller area of ​​the trapezoidal body faces the air inlet, and the duct airflow enters from the gap of the grille; the upper end of the grille is connected to one end of the actuating connecting rod by using a hexagonal boss structure, and the lower end of the grille is placed in a conical hole on the inner wall of the duct by using a conical structure; the fixing ring is sleeved on the outer wall of the duct outlet of the variable cycle engine, the hydraulic actuator is connected to the fixing ring, and the other end of the actuating connecting rod is hinged to the fixing ring; wherein, the fixing ring is driven by the hydraulic actuator to rotate the actuating connecting rod, and then the grille rotates with the actuating connecting rod to adjust the duct area, and the rotation range is 0° to 90°, 90° corresponds to the single duct mode of the variable cycle engine, 0° corresponds to the double duct mode of the variable cycle engine, and other angles correspond to the transition state of the variable cycle engine.

[0009] One end of the actuating connecting rod is provided with a hexagonal inner hole, and the grille and the actuating connecting rod are fixedly connected through the cooperation of the hexagonal boss and the hexagonal inner hole.

[0010] The fixing ring is hinged to the actuating connecting rod by bolts, a through hole is arranged on the fixing ring, and the length of the actuating connecting rod is smaller than the distance between two adjacent through holes on the fixing ring.

[0011] The angle between the grille and the horizontal is 45°, and the inclination angles of the two side edges of the grille are 40°.

[0012] There are 32 grilles.

[0013] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0014] Each grille of the present invention has an inclination angle of 45°, and the internal airflow can be well diffused to the entire mixing section. In the variable cycle engine small bypass ratio mode, the area of ​​the external bypass is the smallest at this time, and the corresponding rotation angle of the grille is 90°. The external bypass airflow passing through the gaps between the grilles will produce high-intensity vortices due to the special structure of the grille when the airflow passes through the grille. The external bypass airflow is injected from 31 grille gaps into the internal bypass airflow that has filled the entire mixing section, forming a huge mixing area, and quickly exchanging energy to achieve the purpose of improving the mixing efficiency and shortening the mixing section. The grille is a trapezoidal block, and the two sides with an inclination angle of 40° can drain well, thereby reducing the total pressure loss. In the variable cycle engine double external bypass mode, the corresponding rotation angle of the grille is 0°. When the airflow flows through the grille, since one side of the grille is a curved surface, it can disturb the airflow to produce a vortex, and can be fully mixed with the internal airflow to improve the thermal mixing efficiency.

[0015] The present invention makes the inner and outer airflows mix more evenly, greatly shortens the mixing distance, and further improves the airflow uniformity at the afterburner inlet to the greatest extent, increases the combustion efficiency of the afterburner, and thus improves the thrust performance of the variable cycle engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the variable cycle engine in single external mode when the grille is at 90°;

[0017] Figure 2 It is the structural schematic diagram of the actuating connecting rod;

[0018] Figure 3 is a schematic diagram of the structure of the fixed ring;

[0019] Figure 4 This is a schematic diagram of the grille installation distribution;

[0020] Figure 5 for Figure 4 Enlarged view of the connection between the actuating link and the grille in the middle A section;

[0021] Figure 6 It is a schematic diagram of the overall assembly of the present invention.

[0022] Markings in the attached drawings: 1-outer duct inlet, 2-inner duct inlet, 3-center cone, 4-grid, 5-actuating connecting rod, 6-fixing ring, 7-hydraulic actuator. DETAILED DESCRIPTION

[0023] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0024] like Figure 6 As shown, the rear duct ejector of the variable cycle engine is provided with an outer duct inlet 1, an inner duct inlet 2 and a central cone 3. The variable area part of the rotating grille type rear duct ejector for a variable cycle engine described in the present invention is arranged in the outer duct.

[0025] like Figures 1 to 6 As shown, this embodiment is a rotary grid type rear duct ejector for a variable cycle engine, comprising a grid 4, an actuating connecting rod 5, a fixing ring 6, and a hydraulic actuator 7;

[0026] The grille 4 is evenly distributed at the outlet of the variable cycle engine duct, and the grille 4 is arranged in a trapezoidal shape, with the shorter side of the trapezoidal body facing the air inlet, and the duct airflow enters from the gap of the grille; the upper end surface of the grille 4 is connected to one end of the actuating connecting rod 5, and the lower end surface of the grille 4 is connected to the inner wall of the duct; the fixing ring 6 is sleeved on the outer wall of the outlet of the variable cycle engine duct, the hydraulic actuator 7 is connected to the fixing ring 6, and the other end of the actuating connecting rod 5 is hinged to the fixing ring 6;

[0027] Among them, the hydraulic actuator 7 pushes the fixed ring 6 to drive the actuating connecting rod 5 to rotate, and then the grille 4 rotates with the actuating connecting rod 5 to adjust the outer duct area. The rotation range is 0° to 90°. 90° corresponds to the single outer duct mode of the strain cycle engine, 0° corresponds to the double outer duct mode of the strain cycle engine, and other angles correspond to the transition state of the strain cycle engine.

[0028] The upper end surface of the grille 4 is provided with a hexagonal boss, one end of the actuating connecting rod 5 is provided with a hexagonal inner hole, and the grille 4 and the actuating connecting rod 5 are fixedly connected through the hexagonal boss and the hexagonal inner hole.

[0029] The lower end surface of the grille 4 is provided with a cone, and the inner wall of the outer duct is provided with a conical hole matched with the cone, so that the cone can rotate in the conical hole.

[0030] The grille 4 is set to be a trapezoidal body, so that the total pressure loss can be reduced, and the duct airflow can easily pass through the side of the grille 4 and the gap between the grilles 4 to flow out. Specifically, in this embodiment, 32 grilles are evenly distributed at the duct outlet, and the angle between the grille 4 and the horizontal is 45°. The size of the grille 4 is determined according to the size of the engine duct. The lower end of the grille 4 is a fixed foot combined with a cone and a cylindrical boss, which is connected to the conical hole on the inner wall of the duct; the upper end is a connecting end combined with a cylindrical boss and a hexagonal boss, which is connected to the actuating connecting rod. The size of the above cylindrical boss is determined according to the size of the grille. The gap between the grille and the inner and outer walls of the variable cycle engine duct does not exceed one tenth of the grille area, so that the duct airflow mainly passes through the gap between the grilles under small bypass ratio conditions.

[0031] The shape of the end of the actuating connecting rod 5 connected to the grille 4 is a hexagonal inner hole, and its length is slightly shorter than the length of the hexagonal boss. The end of the actuating connecting rod 5 connected to the fixing ring 6 is circular, and an M5 through hole is opened at the center of the circle. 32 M5 through holes are evenly distributed on the fixing ring 6, and their positions correspond to the evenly distributed through holes on the actuating connecting rod 5.

[0032] The present invention provides a rotary grid type rear duct ejector for a variable cycle engine, which can effectively enhance the mixing of the internal and external duct airflows of an aircraft engine and relatively reduce the total pressure loss during the mixing process. The working principle is as follows:

[0033] Figure 1The figure is a three-dimensional diagram of the grille. When the air flows through these grilles, most of the air flows through the two sides with an inclination angle of 40°. The sides can guide the air well and then flow into the mixing section through the grille gaps, thereby reducing the total pressure loss. The outer duct airflow passing through the gaps between the grilles will produce high-intensity vortices due to the special structure of the grille. The outer duct airflow is injected from the 31 grille gaps into the inner duct airflow that has filled the entire mixing section, increasing the contact area between the inner and outer duct airflows, forming a huge mixing area, and quickly exchanging energy, so as to achieve the purpose of improving the mixing efficiency and shortening the mixing section. Figure 2 It is a three-dimensional diagram of the actuating connecting rod 5 of the present invention, which connects the fixed ring 6 and the grille 4. When the hydraulic actuator 7 works, the fixed ring 6 is driven to move, and the actuating connecting rod 5 is connected to the fixed ring 6, which in turn drives the actuating connecting rod 5 to rotate. The actuating connecting rod 5 also drives the grille 4 to rotate to achieve the purpose of adjusting the area.

[0034] The grille 4 of the present invention has an inclination angle of 45° with the horizontal, and is trapezoidal in shape. The inclination angles of its two side surfaces are 40°, and the related dimensions should be based on the dimensions of the variable cycle engine rear duct ejector and the premise of ensuring that the inner and outer duct areas meet the overall requirements of the inner and outer duct aerodynamic area, so as to improve the mixing efficiency of the inner and outer duct airflow and reduce the total pressure loss as much as possible.

[0035] Figure 3 It is a three-dimensional diagram of the fixed ring 6. All the actuating connecting rods 5 are fixed at the same tilt angle to ensure that the rotation angles of all the grilles 4 are equal when the area is adjusted. Figure 4 This is a schematic diagram of the installation distribution of the grille 4, which is mainly used to determine the rotation direction, angle, quantity and geometric distribution of the grille 4.

[0036] The present invention sets 32 grilles, and most of the external duct airflow passes through the gaps between the grilles. When the airflow passes through the grilles, due to the special structure of the grilles, a high-intensity vortex will be generated, thereby forming a huge mixing area behind the grilles, and quickly exchanging energy, so as to achieve the purpose of improving the mixing efficiency and shortening the mixing section. In the variable cycle engine large bypass ratio mode, when the airflow flows through the grille, since one side of the grille is a curved surface, it can cause a large disturbance to the airflow flowing through, and after entering the mixing section, it can also be well mixed with the internal airflow. The rotating grille-type rear duct ejector designed by the present invention has a very large advantage over the traditional translational and rotary area-adjusted rear duct ejectors, which makes the internal and external duct airflows mix evenly to a greater extent and greatly reduces the mixing distance. In addition, the airflow uniformity at the inlet of the afterburner is improved to the greatest extent, the combustion efficiency of the afterburner is increased, thereby improving the thrust performance of the variable cycle engine, and its principle is simple and has a high application prospect.

Claims

1. A rotating grid type rear duct ejector for a variable cycle engine, characterized in that: It includes a grille, an actuating connecting rod, a fixed ring, and a hydraulic actuator; the grille is evenly distributed at the variable cycle engine duct outlet, the grille is trapezoidal, and the side of the trapezoidal body with a smaller area faces the air inlet, and the duct airflow enters from the grille gap; the upper end of the grille is connected to one end of the actuating connecting rod using a hexagonal boss structure, and the lower end of the grille is placed in a conical hole on the inner wall of the duct using a conical structure; the fixed ring is sleeved on the outer wall of the variable cycle engine duct outlet, the hydraulic actuator is connected to the fixed ring, and the other end of the actuating connecting rod is hinged to the fixed ring; wherein, the fixed ring is driven by the hydraulic actuator to rotate the actuating connecting rod, and then the grille rotates with the actuating connecting rod to adjust the duct area, and the rotation range is 0° to 90°, 90° corresponds to the single duct mode of the variable cycle engine, 0° corresponds to the double duct mode of the strain cycle engine, and other angles correspond to the transition state of the strain cycle engine.

2. A rotary grid type rear duct ejector for a variable cycle engine as claimed in claim 1, characterized in that: One end of the actuating connecting rod is provided with a hexagonal inner hole, and the grille and the actuating connecting rod are fixedly connected through the cooperation of the hexagonal boss and the hexagonal inner hole.

3. A rotary grid type rear duct ejector for a variable cycle engine as claimed in claim 1, characterized in that: The fixing ring and the actuating connecting rod are hinged by bolts, the fixing ring is provided with through holes for inserting the bolts, and the length of the actuating connecting rod is smaller than the distance between two adjacent through holes on the fixing ring.

4. A rotary grid type rear duct ejector for a variable cycle engine as claimed in claim 1, characterized in that: The angle between the grille and the horizontal is 45°, and the inclination angles of the two side edges of the grille are 40°.

5. The rotary grid type rear duct ejector for a variable cycle engine according to claim 1, characterized in that: There are 32 grilles.

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