CN113090410B - Self-adaptive circulating engine S-shaped spray pipe with impact-air film cooling structure - Google Patents

Abstract

The invention relates to an adaptive cycle engine S-shaped bent spray pipe with an impact-air film cooling structure, belonging to the field of aircraft engines; comprises a convergence section, an expansion section and a third duct; the third duct is provided with two outlets, the first outlet is positioned at the throat of the spray pipe and is of an impact-air film cooling structure; the second outlet is positioned at the exhaust port of the spray pipe and consists of a plurality of first film cooling holes arranged on the circumferential surface of the spray pipe; the impingement-film cooling structure comprises impingement cooling holes, second film cooling holes, a support plate and a rectifying plate, wherein the outer wall surface of the spray pipe and the inner wall surface of the spray pipe are fixedly supported through the support plate and the rectifying plate; the plurality of impingement cooling holes are circumferentially arranged on the outer wall surface of the spray pipe, so that cold air flow in the third duct passes through the impingement cooling holes and is sprayed to the inner wall surface of the spray pipe; the plurality of second air film cooling holes are circumferentially arranged on the inner wall surface of the spray pipe and are positioned on the expansion section side of the spray pipe; the invention prevents the large thermal stress generated by the large temperature difference between the inner side and the outer side of the wall surface of the spray pipe, reduces the thermal stress and protects the wall surface.

Description

An S-curved nozzle of an adaptive cycle engine with impingement-film cooling structure

technical field

The invention belongs to the field of aero-engines, and in particular relates to an S-curved nozzle of an adaptive cycle engine with an impact-film cooling structure.

Background technique

The variable cycle engine regulates the thermal cycle characteristics of the engine by changing the position, geometric size and shape of the internal components of the engine, so that it can take into account the advantages of low-speed and high-speed flight performance, so it will be widely used in the new generation of fighter jets. Adaptive cycle engine is the latest generation of variable cycle engine. Its biggest feature is that it has three flow channels, so it has more working modes and stronger cycle adjustment ability. At the present stage, most nozzle designs for adaptive cycle engines are for axisymmetric convergent nozzles, which can only be used for subsonic flight. In order to achieve transonic and supersonic flight, it is necessary to study the design of the retractable nozzle for the adaptive cycle engine.

The new generation of fighter jets not only have more requirements for the working mode of the aircraft, but also put forward higher requirements for its stealth and maneuverability. The most important thing to improve the stealth of aircraft is to reduce the infrared radiation signal and electromagnetic radiation signal of the aircraft, and the exhaust system of the aircraft is the strongest source of infrared radiation and an important source of electromagnetic radiation. With its curved configuration, the S-curved nozzle can effectively shield the high-temperature components in the exhaust system to reduce its infrared radiation characteristics. At the same time, the curved configuration also makes the electromagnetic signal continuously refracted and dissipated. The S-curved nozzle also has a rectangular outlet for easy It is widely used in fighter jets due to its advantages such as fusion with the fuselage. The new generation of fighter jets has higher requirements on the maneuverability of the aircraft. The most effective way is to increase the temperature before the turbine of the aircraft, which will lead to overheating and damage to the nozzle. At the same time, the high-temperature nozzle wall and tail jet will increase the infrared radiation characteristics of the exhaust system and reduce the stealth of the S-bend nozzle. Therefore, it is necessary to study the nozzle cooling technology in depth.

At present, the research on the cooling of axisymmetric nozzles and binary nozzles has become a hot topic. The article "Preliminary Experimental Research on Wall Surface Cooling of Binary Converging and Expanding Nozzles under the Condition of High-speed Thermal Jet Flow" shows that after cooling, each The wall temperature in the diverging section of the nozzle drops significantly. For the turbofan engine, the complex large-curvature multi-bend circle-to-square geometry of the S-bend nozzle makes the high-temperature air flow inside the S-bend nozzle turn outward and invade the wall of the nozzle, forming a local high-temperature area, that is, the hot spot phenomenon. The hot spot area will cause thermal deformation of the local nozzle in the hot spot area. The adaptive cycle engine has three ducts. In addition to local hot spots, the cold air flow in the third duct outside the nozzle wall and the high-temperature air flow inside the nozzle wall act on the nozzle wall at the same time, which will cause the inside and outside of the nozzle wall The temperature difference is large and damaged. If the cooling technology of the binary nozzle is directly applied to the adaptive cycle engine, it will not only fail to solve the problem of large temperature difference between the inside and outside, but may also affect the mainstream of the engine. Therefore, it is necessary to take effective cooling measures for adaptive cycle engines.

Contents of the invention

Technical problem to be solved:

In order to avoid the deficiencies of the prior art, the present invention proposes an adaptive cycle engine S-bend nozzle with an impact-film cooling structure, which solves the thermal stress on the inner and outer walls of the adaptive cycle engine S-bend nozzle in the prior art. The problem of large and large damage, the problem of local damage caused by local heating, and the problem of high infrared radiation caused by the wall surface of the high-temperature nozzle and the high-temperature exhaust gas.

The technical solution of the present invention is: an S-curved nozzle of an adaptive cycle engine with an impact-film cooling structure, which is sequentially divided into a converging section and an expanding section along the airflow direction, and a third duct is arranged on the periphery; the entrance of the converging section It is the air inlet of the nozzle, including the inner air inlet and the outer air inlet, the outlet of the expansion section is the exhaust port of the nozzle, and the junction of convergence and expansion forms the throat of the nozzle; it is characterized in that: The third duct is provided with two outlets, the first outlet is located at the throat of the nozzle, which is an impact-film cooling structure; the second outlet is located at the exhaust port of the nozzle, and is formed by a number of first A film cooling hole is formed;

The flow channel profile of the nozzle is composed of the inner wall surface of the nozzle and the outer wall surface of the nozzle, and the outer wall surface of the nozzle is set on the periphery of the inner wall surface of the nozzle, and the first outlet of the third duct is formed at the overlap;

The impingement-film cooling structure of the first outlet includes an impingement cooling hole, a second film cooling hole, a support plate and a rectifying plate, and the entrance of the outer wall surface of the nozzle and the inner wall surface of the nozzle are fixedly supported by a support plate, The outlet of the inner wall of the nozzle and the outer wall of the nozzle are fixedly supported by a rectifying plate; several impact cooling holes are arranged on the outer wall of the nozzle along the circumferential direction, so that the cold air flow in the third duct passes through the impact cooling holes and sprays to the nozzle. The inner wall surface of the tube changes the heat transfer coefficient between the fluid and the wall surface; several second film cooling holes are arranged on the inner wall surface of the nozzle along the circumferential direction and are located on the side of the expanding section of the nozzle; the cooling air flows in through the second film cooling holes It is also covered on the inner side of the nozzle wall, which isolates the internal heat flow from scouring the nozzle wall.

A further technical solution of the present invention is that: both the support plate and the rectifying plate are annular sheet structures, and small holes are opened on the rectifying plate, and part of the cooling air flow flowing into the cavity of the impact-air film cooling structure passes through the air film cooling The holes flow into the inside of the nozzle, and another part of the cooling air flows in through the small holes on the rectifying plate and adheres to the wall of the nozzle.

A further technical solution of the present invention is: the support plate at the front end of the outer wall of the nozzle and the rectifying plate at the rear end of the inner wall of the nozzle connect the outer wall of the nozzle and the inner wall of the nozzle as a whole.

A further technical solution of the present invention is: both the converging section and the dilating section are nearly S-shaped, and the axial length ratio between the converging section and the dilating section is between 1:2 and 3:2;

A further technical solution of the present invention is: the convergent section of the nozzle is formed by the inner wall of the nozzle; the first 1\3 of the expansion section of the nozzle is formed by the inner wall of the nozzle, and the rear 2\3 is formed by the outer wall of the nozzle; the inner wall of the nozzle The overlapping portion with the outer wall of the nozzle is the part from the rear 1\3 of the nozzle convergent section to the front 1\3 of the nozzle expansion section.

A further technical solution of the present invention is: the axial direction of the impact cooling holes is perpendicular to the inner wall of the nozzle to ensure the intensity of the impact heat exchange; D, The distance between adjacent holes in the circumferential direction is 2D to 6D, and the row spacing of holes is 2D to 10D.

A further technical solution of the present invention is: the film cooling hole is an oblique hole, the angle between the axial direction of the hole and the inner wall of the nozzle is 15° to 75°, the arrangement of the film cooling holes, the hole spacing, and the hole spacing Consistent with impingement cooling holes.

A further technical solution of the present invention is: the ratio of the length of the nozzle to the diameter of the nozzle inlet is 1.8 to 3, the nozzle inlet cross section is circular, the nozzle throat cross section is rectangular, and the exhaust outlet cross section is Rectangular; wherein, the ratio of the width of the nozzle throat to the diameter of the air inlet is 0.7-1.6, and the ratio of the width to height of the exhaust port is 3-15.

A further technical solution of the present invention is: the third duct includes a third duct entrance, a third duct support plate, and a third duct outer wall; the third duct entrance is connected to a third duct fan, and the flow The airflow passing through the third duct is a high-pressure cold airflow; the outer wall of the third duct is fixedly connected to the inner wall of the nozzle and the outer wall of the nozzle through a plurality of third duct support plates, and the outer wall of the third duct and the outer wall of the nozzle The wall surface forms the flow channel of the third duct.

A further technical solution of the present invention is: the third duct support plate is an annular thin plate, one end of which is connected to the outer wall of the third duct, and the other end is connected to the outer wall of the nozzle or the inner wall of the nozzle, so that the outer wall of the third duct is connected to the inner wall of the nozzle. The wall surface of the nozzle forms a whole, and the third duct support plate is evenly distributed at 5-10 places along the axial direction of the nozzle; It will flow in the third channel through the small hole.

Beneficial effect

The beneficial effects of the present invention are: the present invention proposes an S-curved nozzle of an adaptive cycle engine with an impact-film cooling structure, which consists of an S-shaped converging section, an S-shaped expanding section, a third duct structure and an impact - Composition of film cooling structure. Applying the S-curved nozzle of the self-adaptive cycle engine with the impingement-film cooling structure of the present invention, the nozzle is cooled by convective heat exchange between the cooling air flowing in the third duct and the outside of the wall of the nozzle, and the cold air flows into the nozzle through the impact cooling hole Impact film cooling structure channel, and impact heat exchange on the outside of the inner wall of the nozzle. At the same time, the cooling air flows in through the film cooling holes and the small holes on the rectifier plate and covers the inside of the nozzle wall, which isolates the internal heat flow from spraying. The wall surface of the nozzle is scoured to fully cool the inner side of the nozzle wall surface, which prevents the large thermal stress caused by the large temperature difference between the inside and outside of the nozzle wall surface, reduces the thermal stress, and protects the wall surface. Moreover, the air film layer prevents the internal high-temperature airflow from turning outward and invading the wall of the nozzle, thus inhibiting the formation of hot spots. The small holes on the rectification plate rectify the airflow in the third duct, and limit the direction of the airflow into the nozzle, so that the cold air in the third duct can flow along the direction of the main flow, which has better adhesion to the wall , not only to achieve the best cooling effect, but also to prevent the mixing loss of the third channel airflow and the main flow, ensuring the aerodynamic performance of the nozzle. After cooling, the temperature of the wall surface and the tail jet will decrease, and the intensity of its infrared radiation will also decrease accordingly, which enhances the infrared stealth of the S-bend nozzle.

The present invention arranges the impact-film cooling structure at the outlet of the third duct, and limits the impact-film cooling structure to the throat of the nozzle, which can reduce the back pressure and control the position of the shock wave in the air channel, so that the third The ducted cold air flow does not enter the core engine, and achieves the effect of nozzle wall cooling without affecting the normal operation of the engine; at the same time, the cold air flow passes through the impact-air film cooling structure to wrap the core flow, which can change the shear of the jet flow. Slicing distribution to reduce noise.

The principle of impact-film cooling is shown in Figure 1, in which the impact cooling is mainly aimed at increasing the surface heat transfer coefficient between the fluid and the wall, and at the same time reducing the heat transfer temperature. The heat transfer rate of impact cooling is: Q=h _j (T _m -T _w ), where h _j is the impact surface heat transfer coefficient, T _m is the impact heat transfer temperature, that is, the mixing of the impact fluid and the ambient fluid at the place close to the wall surface Mixing temperature, _Tw is the impact heat transfer wall temperature. Compared with convective heat transfer, the heat transfer coefficient of impact heat transfer is much larger, so the heat transfer is more and the cooling effect is better. The film cooling is mainly to cool the nozzle by covering the wall of the high-temperature nozzle, isolating the high-temperature gas, and reducing the heat exchange temperature of the fluid. Applying the S-curved nozzle of adaptive cycle engine with impingement-film cooling structure of the present invention solves the problem of destruction of the S-curved nozzle of adaptive cycle engine in the prior art due to large thermal stress inside and outside the wall surface, local heat The problem of local damage caused by the shift and the problem of high infrared radiation caused by the wall surface of the high-temperature nozzle and the high-temperature exhaust gas.

Description of drawings

Fig. 1 is the impact-film cooling schematic diagram of the embodiment of the present invention;

Fig. 2 is a schematic diagram of an adaptive cycle engine S-curved nozzle with an optional impingement-film cooling structure according to an embodiment of the present invention;

Explanation of reference signs: T ₁ , the temperature of the impinging jet; T ₂ , the temperature of the fluid around the target surface; T _m , the temperature of the impinging heat transfer; T _w , the wall temperature of the impinging heat transfer; 1, the convergence section; 11, the air intake 12. Connotative air inlet; 13. Outer culvert air inlet; 2. Expansion section; 21. Exhaust port; 3. Inner wall of nozzle; 4. Outer wall of nozzle; 5. Throat of nozzle; 6. The third duct structure; 61, the entrance of the third duct; 62, the support plate of the third duct; 63, the outer wall of the third duct; 7, the impact-air film cooling structure; 71, the impact cooling hole; 72, the air film Cooling hole; 73, support plate; 74, rectifying plate.

Detailed ways

The embodiments described below by referring to the figures are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

In describing the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " Orientation indicated by rear, left, right, vertical, horizontal, top, bottom, inside, outside, clockwise, counterclockwise, etc. The positional relationship is based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, Therefore, it should not be construed as limiting the invention.

As shown in Figure 2, an adaptive cycle engine S-curved nozzle with an impingement-film cooling structure of the present invention includes a converging section 1, an expanding section 2, a third duct structure 6 and an impingement-film cooling structure 7 . The first end of the converging section 1 is the air inlet 11 of the nozzle, and this air inlet 11 includes the connotation air inlet 12 and the outer confinement air inlet 13, the second end of the converging section 1 and the first end of the expansion section 2 Connect and form the nozzle throat 5 here, and the second end of the expansion section 2 is the exhaust port 21 of the nozzle. The flow channel profile of the nozzle is composed of the inner wall surface 3 and the outer wall surface 4 of the nozzle. The inner wall surface 3 of the nozzle and the outer wall surface 4 of the nozzle have overlapping parts along the axial direction. The annular cavity formed by the overlapping part constitutes the impact-air The flow channel of the film cooling structure 7.

The third duct structure 6 includes a third duct entrance 61 , a third duct support plate 62 and a third duct outer wall 63 . The third duct inlet 61 is connected to the third duct fan, and the airflow flowing through the third duct is a high-pressure cold airflow. The third duct outer wall 63 is fixedly connected to the nozzle inner wall 3 and the nozzle outer wall 4 through a plurality of third duct support plates 62, and the third duct outer wall 63 and the nozzle wall form a flow channel of the third duct.

Referring to FIGS. 1 and 2 , the impingement-film cooling structure 7 includes an impingement cooling hole 71 , a film cooling hole 72 , a support plate 73 and a rectifying plate 74 . The impingement cooling hole 71 is arranged on the outer wall surface 4 of the nozzle forming the flow channel of the impact-film cooling structure 7, and the cold air flow in the third duct flows into the flow channel of the impact-film cooling structure 7 through the impact cooling hole 71, and It is sprayed vertically to the inner wall surface 3 of the nozzle, thereby changing the heat transfer coefficient between the fluid and the wall surface, and strengthening the heat exchange between the cooling gas and the wall surface. The film cooling holes 72 are arranged on the nozzle expansion section 2 part of the nozzle inner wall surface 3 and the nozzle outer wall surface 4 close to the nozzle exhaust port 21 . The cooling air flow flows in through the film cooling hole 72 and covers the inner side of the nozzle wall, which isolates the internal heat flow from scouring the nozzle wall, prevents the formation of wall heat spots, and reduces the self-pressure between the nozzle inner wall 3 and the nozzle outer wall 4. The temperature difference on both sides of the wall reduces the thermal stress and protects the wall.

The S-curved nozzle of adaptive cycle engine with impingement-film cooling structure of the present invention is applied to solve the problem that the S-curved nozzle of adaptive cycle engine in the prior art is damaged due to the large thermal stress inside and outside the wall surface, and the local heat The problem of local damage caused by the shift and the problem of high infrared radiation caused by the wall surface of the high-temperature nozzle and the high-temperature exhaust gas.

Specifically, both the convergent section 1 and the expansion section 2 are S-shaped, the convergent section 1 of the nozzle is composed of the inner wall surface 3 of the nozzle, the front 1\3 of the expansion section 2 of the nozzle is composed of the inner wall surface 3 of the nozzle, and the rear 2 of the expansion section 2 \3 is composed of the outer wall surface 4 of the nozzle, and the overlapping part of the inner wall surface 3 of the nozzle pipe and the outer wall surface 4 of the nozzle is the part from the rear 1\3 of the nozzle convergent section 1 to the front 1\3 of the nozzle expansion section 2.

Optionally, the axial length ratio of the converging section 1 and the expanding section 2 is between 1:2 and 3:2. The ratio of the length of the nozzle to the diameter of the nozzle inlet 11 is 1.8 to 3, the inlet 11 is circular, the nozzle throat 5 is rectangular, and the exhaust port 21 is rectangular, and the width of the nozzle throat 5 is the same as The diameter ratio of the air inlet 11 is 0.7-1.6, and the aspect ratio of the air outlet 21 is 3-15.

As shown in FIG. 2 , the impingement-film cooling structure 7 includes an impingement cooling hole 71 , a film cooling hole 72 , a support plate 73 and a rectifying plate 74 . The strut plate 73 at the front end of the nozzle outer wall 4 and the rectifying plate 74 at the rear end of the nozzle inner wall 3 connect the nozzle outer wall 4 and the nozzle inner wall 3 into a whole, the nozzle inner wall 3, the outer wall 4, the support plate 73 and The rectifying plates 74 together form the cavity of the impact-film cooling structure 7, the support plate 73 and the rectifying plate 74 are both ring-shaped sheet structures, and the rectifying plate 74 has small holes to flow into the cavity of the impact-film cooling structure 7 Part of the cooling air flows into the nozzle through the film cooling holes 72, and the other part of the cooling air flows in through the small holes on the rectifying plate 74 and adheres to the wall of the nozzle. The impact cooling holes 71 are perpendicular to the inner wall surface 3 of the nozzle to ensure the strength of the impact heat exchange. Two adjacent rows of impact cooling holes 71 are arranged in a row or in a row. 6D, the hole spacing is 2D ~ 10D. The film cooling holes 72 are oblique holes, and the hole inclination angle is 15°-75°. The third duct support plate 62 is an annular thin plate, and one end of the third duct support plate 62 is connected to the third duct outer wall 63, and the other end is connected to the nozzle outer wall 4 or the nozzle inner wall 3, so that the third duct outer wall 63 forms an integral body with the wall surface of the nozzle, and the third duct support plate 62 is evenly distributed in the third duct 5-10 along the axial direction of the nozzle. A plurality of rows of small holes are opened on the support plate 62 of the third duct, and the airflow in the third duct will flow in the third duct through the small holes.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be construed as limitations to the present invention. Variations, modifications, substitutions, and modifications to the above-described embodiments are possible within the scope of the present invention.

Claims (7)

1. An S-shaped bent spray pipe of a self-adaptive cycle engine with an impact-air film cooling structure is sequentially provided with a convergent section and an expansion section along the airflow direction, and a third duct is arranged at the periphery of the S-shaped bent spray pipe; the inlet of the convergent section is an air inlet of the spray pipe and comprises an inner culvert air inlet and an outer culvert air inlet, the outlet of the divergent section is an air outlet of the spray pipe, and a throat of the spray pipe is formed at the joint of the convergent section and the divergent section; the method is characterized in that: the third duct is provided with two outlets, the first outlet is positioned at the throat of the spray pipe and is of an impact-air film cooling structure; the second outlet is positioned at the exhaust port of the spray pipe and consists of a plurality of first film cooling holes arranged on the circumferential surface of the spray pipe;

the spray pipe flow passage molded surface is composed of a spray pipe inner wall surface and a spray pipe outer wall surface, the spray pipe outer wall surface is sleeved on the periphery of the spray pipe inner wall surface, and a first outlet of a third duct is formed at the overlapping position;

the impingement-film cooling structure of the first outlet comprises an impingement cooling hole, a second film cooling hole, a support plate and a rectifying plate, wherein the inlet of the outer wall surface of the spray pipe and the inner wall surface of the spray pipe are fixedly supported through the support plate, and the outlet of the inner wall surface of the spray pipe and the outer wall surface of the spray pipe are fixedly supported through the rectifying plate; the plurality of impingement cooling holes are circumferentially arranged on the outer wall surface of the spray pipe, so that cold air flow in the third duct passes through the impingement cooling holes and is sprayed to the inner wall surface of the spray pipe, and the heat exchange coefficient between the fluid and the wall surface is changed; the plurality of second air film cooling holes are circumferentially arranged on the inner wall surface of the spray pipe and are positioned on the expansion section side of the spray pipe; cooling airflow flows into the second air film cooling holes and covers the inner side of the wall surface of the spray pipe, so that the erosion of the inner heat flow on the wall surface of the spray pipe is isolated;

the axial direction of the impingement cooling hole is vertical to the inner wall surface of the spray pipe so as to ensure the intensity of impingement heat exchange; two adjacent rows of impingement cooling holes are arranged in a row-by-row or row-by-row mode, the aperture of the impingement cooling holes is D, the distance between the circumferential adjacent holes is 2D-6D, and the row pitch of the holes is 2D-10D;

the gas film cooling holes are inclined holes, the included angle between the axial direction of the holes and the inner wall surface of the spray pipe is 15-75 degrees, and the arrangement mode, the hole spacing and the hole row spacing of the gas film cooling holes are consistent with those of the impingement cooling holes;

the third duct comprises a third duct inlet, a third duct support plate and a third duct outer wall surface; the third duct inlet is connected to a third duct fan, and the airflow flowing through the third duct is high-pressure cold airflow; the outer wall surface of the third duct is fixedly connected to the inner wall surface of the spray pipe and the outer wall surface of the spray pipe through a plurality of third duct support plates, and the outer wall surface of the third duct and the wall surface of the spray pipe form a flow channel of the third duct.

2. The adaptive cycle engine S-bend nozzle with impingement-film cooling as described in claim 1, wherein: the support plate and the rectifying plate are both of annular sheet structures, small holes are formed in the rectifying plate, one part of cooling airflow flowing into the cavity of the impact-air film cooling structure flows into the spray pipe through the air film cooling holes, and the other part of cooling airflow flows into the spray pipe through the small holes in the rectifying plate and is attached to the wall surface of the spray pipe.

3. The adaptive cycle engine S-bend nozzle with impingement-film cooling as described in claim 1, wherein: the support plate at the front end of the outer wall surface of the spray pipe and the rectifying plate at the rear end of the inner wall surface of the spray pipe connect the outer wall surface of the spray pipe and the inner wall surface of the spray pipe into a whole.

4. The adaptive cycle engine S-bend nozzle with impingement-film cooling arrangement of claim 1, wherein: the convergent section and the divergent section are both in an S shape, and the length ratio of the convergent section to the divergent section in the axial direction is 1:2 to 3.

5. The adaptive cycle engine S-bend nozzle with impingement-film cooling arrangement of claim 1, wherein: the convergent section of the spray pipe is formed by the inner wall surface of the spray pipe; the front 1\3 of the expansion section of the spray pipe is formed by the inner wall surface of the spray pipe, and the rear 2\3 is formed by the outer wall surface of the spray pipe; the overlapped part of the inner wall surface of the spray pipe and the outer wall surface of the spray pipe is the part from the rear 1\3 of the convergent section of the spray pipe to the front 1\3 of the divergent section of the spray pipe.

6. The adaptive cycle engine S-bend nozzle with impingement-film cooling arrangement of claim 1, wherein: the ratio of the length of the spray pipe to the diameter of the air inlet of the spray pipe is 1.8-3, the section of the air inlet of the spray pipe is circular, the section of the throat of the spray pipe is rectangular, and the section of the air outlet of the spray pipe is rectangular; wherein, the ratio of the width of the throat of the spray pipe to the diameter of the air inlet is 0.7-1.6, and the width-height ratio of the air outlet is 3-15.

7. The adaptive cycle engine S-bend nozzle with impingement-film cooling as described in claim 1, wherein: the third duct support plate is an annular thin plate, one end of the third duct support plate is connected with the outer wall surface of the third duct, and the other end of the third duct support plate is connected with the outer wall surface of the spray pipe or the inner wall surface of the spray pipe, so that the outer wall surface of the third duct and the wall surface of the spray pipe form a whole, and the third duct support plate is uniformly distributed at 5-10 positions along the axial direction of the spray pipe; and a plurality of rows of small holes are formed in the third duct support plate, and the airflow in the third duct can flow in the third duct through the small holes.

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