S-shaped spray pipe self-air-entraining wall surface cooling infrared suppression structure and design method thereof

Abstract

The invention relates to the technical field of aero-engines, and discloses an S-shaped spray pipe self-air-entraining wall surface cooling infrared suppression structure and a design method thereof.Outer culvert airflow of a mixer at the front section of an S-shaped spray pipe is guided into the outlet end of the S-shaped spray pipe through an air entraining pipe, the temperature of the wall surface of the outlet section of the S-shaped spray pipe is reduced, and therefore the purpose of reducing infrared radiation signals is achieved; the cooling effect on the wall surface of the outlet of the S-shaped spray pipe can be improved, the pertinence on cooling of the outlet of the spray pipe is high, full-wall-surface cooling of the S-shaped spray pipe is not needed, the problem that the middle section of the S-shaped spray pipe with small contribution to infrared signals is easily overcooled due to the fact that a sleeve is adopted for cooling the whole-course wall surface of the S-shaped spray pipe traditionally is solved, the cost is low, and the service life is long. Therefore, the thrust performance of the engine is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of aeroengines and discloses an S-bend nozzle self-bleeding wall surface cooling infrared suppression structure and a design method thereof. Background Art

[0002] The S-bend nozzle can utilize the curved flow channel design to shield the high-temperature components inside the aircraft engine, such as the turbine and center cone, and can effectively reduce the infrared radiation intensity of the aircraft engine. Therefore, it has received more and more attention.

[0003] The S-bend nozzle outlet section is a rear visible wall with a high temperature, which contributes greatly to the infrared radiation intensity and is an important object that needs to reduce the rear infrared signal. Therefore, the S-bend nozzle outlet section needs to be reasonably cooled. The existing S-bend nozzle cooling structure needs to draw air from the engine compressor to cool the entire nozzle wall by convection heat exchange, which will reduce engine performance. Summary of the invention

[0004] The purpose of the present invention is to provide an S-bend nozzle self-bleeding wall cooling infrared suppression structure and a design method thereof, which can realize the cooling of the S-bend nozzle outlet section without reducing the engine performance, and the cooling efficiency of the S-bend nozzle outlet wall is high, and the cooling of the nozzle outlet is highly targeted, so as to achieve the purpose of reducing infrared radiation signals.

[0005] In order to achieve the above technical effects, the technical solution adopted by the present invention is:

[0006] An S-bend nozzle self-bleeding wall cooling infrared suppression structure, comprising:

[0007] An S-bend nozzle, wherein the inlet end of the S-bend nozzle is connected to the outlet end of the mixer;

[0008] An air inlet hole is provided on the wall of the S-bend nozzle near the inlet of the S-bend nozzle;

[0009] An air inlet hole is provided on the wall of the S-bend nozzle near the outlet of the S-bend nozzle;

[0010] An air bleed pipe is connected between the air bleed hole and the air inlet hole and is used to guide the outer flow of the mixer into the outlet end of the S-bend nozzle.

[0011] Furthermore, there are multiple air bleed holes, which are arranged in a circumferential direction along the inlet end of the S-bend nozzle.

[0012] Furthermore, there are multiple air inlet holes, which are arranged in a circumferential direction along the outlet end of the S-bend nozzle.

[0013] Furthermore, an air collecting cavity is arranged near the outer wall of the outlet end of the S-bend nozzle, and the air inlet hole is opened on the air collecting cavity; an air inlet channel connecting the air collecting cavity and the S-bend nozzle is opened on the S-bend nozzle wall corresponding to the air collecting cavity.

[0014] Furthermore, the air inlet passage is a hole or a slit, or a combination of the two.

[0015] Furthermore, the air bleed angle of the air bleed pipe ranges from 0 to 20 degrees, and the air bleed angle is the angle between the air inlet end of the air bleed pipe and the axial direction of the mixer.

[0016] In order to achieve the above technical effects, the present invention also provides a method for designing an S-bend nozzle self-bleeding wall cooling infrared suppression structure, which is used to obtain the bleed angle of the S-bend nozzle self-bleeding wall cooling infrared suppression structure, and includes:

[0017] According to the structural dimensions of the S-bend nozzle, a three-dimensional model of the S-bend nozzle including the air bleed hole, the air inlet hole and the air bleed pipe is constructed;

[0018] Under the engine design operating conditions, the S-bend nozzle outlet wall temperature corresponding to different air bleed angles is obtained by simulation;

[0019] According to the air entrainment angle and the corresponding wall temperature, a functional relationship between the air entrainment angle and the wall temperature is constructed;

[0020] According to the required value of the wall temperature of the engine S-bend nozzle outlet, the functional relationship is used to analyze and obtain the corresponding analysis value of the bleed air angle.

[0021] Furthermore, the air entrainment angle ranges from 0 to 20°. If the air entrainment angle analysis value is greater than or equal to 20°, the air entrainment angle is 20°.

[0022] Compared with the prior art, the present invention has the following beneficial effects: the present invention introduces the outer flow of the mixer at the front section of the S-bend nozzle into the outlet end of the S-bend nozzle through the air bleed pipe, thereby reducing the wall temperature of the outlet section of the S-bend nozzle, thereby achieving the purpose of reducing the infrared radiation signal; the cooling effect on the outlet wall of the S-bend nozzle can be improved, the cooling of the nozzle outlet is highly targeted, and there is no need to cool the entire wall of the S-bend nozzle, thereby avoiding the problem of excessive cooling of the middle section of the S-bend nozzle which contributes less to the infrared signal due to the traditional use of a sleeve to cool the entire wall of the S-bend nozzle, with low cost, thereby ensuring the engine thrust performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of infrared suppression structure of S-bend nozzle self-bleeding wall cooling in the embodiment;

[0024] Figure 2 This is a schematic diagram of the structure of installing the gas collecting chamber at the outlet of the S-bend nozzle in the embodiment;

[0025] Figure 3 It is a flow chart of the design method of the infrared suppression structure of the S-bend nozzle self-bleeding wall cooling in the embodiment;

[0026] Figure 4 Statistical diagram of the temperature of the wall surface at the outlet of the S-bend nozzle when there is an air bleed pipe or not in the embodiment;

[0027] Among them, 1. S-bend nozzle; 2. mixer; 3. air inlet; 4. air bleed pipe; 5. air collecting chamber; 6. air inlet channel. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with the embodiments and drawings. However, it should not be understood that the scope of the above subject matter of the present invention is limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0029] Example

[0030] See also Figure 1 and Figure 2 , an S-bend nozzle self-bleeding wall cooling infrared suppression structure, comprising:

[0031] An S-bend nozzle 1, wherein the inlet end of the S-bend nozzle 1 is connected to the outlet end of the mixer 2;

[0032] An air inlet hole, which is provided on the wall of the S-bend nozzle 1 near the inlet of the S-bend nozzle 1;

[0033] An air inlet 3, wherein the air inlet 3 is provided on the wall of the S-bend nozzle 1 close to the outlet of the S-bend nozzle 1;

[0034] The air bleed pipe 4 is connected between the air bleed hole and the air inlet hole 3 and is used to guide the outer flow of the mixer 2 into the outlet end of the S-bend nozzle 1.

[0035] In this embodiment, the outer flow of the mixer 2 at the front section of the S-bend nozzle 1 is introduced into the outlet end of the S-bend nozzle 1 through the air bleed pipe 4, so as to reduce the wall temperature of the outlet section of the S-bend nozzle 1, thereby achieving the purpose of reducing the infrared radiation signal; the cooling effect on the outlet wall of the S-bend nozzle 1 can be improved, and the cooling of the nozzle outlet is highly targeted, and there is no need to cool the entire wall of the S-bend nozzle 1, thereby avoiding the problem of excessive cooling of the middle section of the S-bend nozzle 1 which contributes less to the infrared signal due to the traditional use of a sleeve to cool the entire wall of the S-bend nozzle 1, with a low cost, thereby ensuring the engine thrust performance.

[0036] In the present embodiment, there are multiple air bleed holes, and the multiple air bleed holes are arranged circumferentially along the inlet end of the S-bend nozzle 1. There are multiple air inlet holes 3, and the multiple air inlet holes 3 are arranged circumferentially along the outlet end of the S-bend nozzle 1. In the present embodiment, the number of air bleed holes and the number of air inlet pipes can be equal, that is, the air bleed holes and the air inlet holes 3 are one-to-one corresponding, and each air bleed hole and an air inlet hole 3 are connected through an air bleed pipe 4. It should be noted that the number of air bleed holes and the number of air inlet pipes can also be unequal, for example, two or more air bleed pipes 4 are connected to one air inlet hole 3 through an air bleed pipe 4 with a flow collecting function, or one air bleed hole is connected to multiple air inlet holes 3 through an air bleed pipe 4 with a flow diversion function, so as to achieve the purpose of cooling the outlet wall of the S-bend nozzle 1.

[0037] In this embodiment, a gas collecting cavity 5 is provided near the outer wall of the outlet end of the S-bend nozzle 1, and the air inlet hole 3 is provided on the gas collecting cavity 5; an air inlet passage 6 connecting the gas collecting cavity 5 and the S-bend nozzle 1 is provided on the wall of the S-bend nozzle 1 corresponding to the gas collecting cavity 5. The cooling gas is distributed to the introduced external cooling airflow through the gas collecting cavity 5, thereby ensuring a uniform cooling effect on the outlet wall of the S-bend nozzle 1 and reducing the problem of uneven circumferential temperature stress on the outlet wall of the S-bend nozzle 1.

[0038] In this embodiment, the air inlet channel 6 is one or a combination of holes or slits. Specifically, the specific distribution or configuration of the air inlet channel 6 can be set according to the pressure distribution of the nozzle outlet section and the design requirements of cooling efficiency.

[0039] In order to reduce the total pressure loss of bleed air, the bleed air angle of the bleed air pipe 4 in this embodiment is in the range of 0-20°, which is the axial angle between the air inlet end of the bleed air pipe 4 and the mixer 2, ensuring that the bleed air direction of the bleed air pipe 4 matches the external flow of the mixer 2. Figure 3 Regarding the specific design of the air entrainment angle, the method adopted in this embodiment includes the following design steps:

[0040] Step 1: construct a three-dimensional model of the S-bend nozzle 1 including an air bleed hole, an air inlet hole 3 and an air bleed pipe 4 according to the structural dimensions of the S-bend nozzle 1;

[0041] Step 2: Under the engine design operating conditions, simulate and obtain the outlet wall temperature of the S-bend nozzle 1 corresponding to different air bleed angles;

[0042] Step 3: constructing a functional relationship between the air entrainment angle and the wall temperature according to the air entrainment angle and the corresponding wall temperature;

[0043] Step 4: According to the required value of the wall temperature at the outlet of the engine S-bend nozzle 1, the corresponding analysis value of the bleed air angle is obtained by using the functional relationship analysis.

[0044] The method obtains the air bleed angle and the outlet wall temperature of the S-bend nozzle 1 through simulation analysis, and constructs a functional relationship between the air bleed angle and the wall temperature, so as to determine the effect of the corresponding analysis angle on the outlet wall temperature of the S-bend nozzle 1, and then sets the air bleed angle according to needs, which can adapt to the mixer 2 structure of different configurations to ensure the best air bleed and cooling effects.

[0045] In this embodiment, the air entrainment angle range is first assumed to be 0 to 20°. If the air entrainment angle analysis value is greater than or equal to 20°, the air entrainment angle is taken as 20°.

[0046] This embodiment is aimed at the design point working condition of a certain type of aircraft engine S-bend nozzle. First, the outlet wall temperature of the S-bend nozzle 1 without the bleed air pipe is simulated and evaluated. Then, air is bleed from the first bend of the S-bend nozzle 1 through 8 bleed air hoses (such as Figure 1 The air bleed position is the upper and lower walls of the first bend of the S-bend nozzle 1. According to the analysis, the air bleed angle and the axial angle of the mixer 2 are in the range of 0 to 3 degrees. The outlet wall temperature of the S-bend nozzle 1 with air bleed pipe cooling is obtained through simulation analysis, and the statistical graph of the outlet wall temperature of the S-bend nozzle with and without air bleed pipe is obtained as shown in the figure. Figure 4 As shown in the figure, the temperature reduction effect of the outlet wall of the S-bend nozzle 1 can be analyzed. Figure 4 In the analysis condition, the average wall temperature of the S-bend nozzle 1 outlet section decreased by 8.6%, and the maximum wall temperature of the outlet section decreased by 11.3%.

[0047] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An S-bend nozzle self-bleeding wall cooling infrared suppression structure, characterized in that: include: An S-bend nozzle, wherein the inlet end of the S-bend nozzle is connected to the outlet end of the mixer; An air inlet hole is provided on the wall of the S-bend nozzle near the inlet of the S-bend nozzle; An air inlet hole is provided on the wall of the S-bend nozzle near the outlet of the S-bend nozzle; An air bleed pipe is connected between the air bleed hole and the air inlet hole and is used to guide the outer flow of the mixer into the outlet end of the S-bend nozzle.

2. The S-bend nozzle self-bleeding wall cooling infrared suppression structure according to claim 1 is characterized in that: There are multiple air bleed holes, which are arranged in a circumferential direction along the inlet end of the S-bend nozzle.

3. The S-bend nozzle self-bleeding wall cooling infrared suppression structure according to claim 2 is characterized in that: There are multiple air inlet holes, which are arranged in a circumferential direction along the outlet end of the S-bend nozzle.

4. The S-bend nozzle self-bleeding wall cooling infrared suppression structure according to claim 1, characterized in that: An air collecting cavity is arranged near the outer wall of the outlet end of the S-bend nozzle, and the air inlet hole is opened on the air collecting cavity; an air inlet channel connecting the air collecting cavity and the S-bend nozzle is opened on the wall of the S-bend nozzle corresponding to the air collecting cavity.

5. The S-bend nozzle self-bleeding wall cooling infrared suppression structure according to claim 4, characterized in that: The air inlet passage is a hole or a slit, or a combination of the two.

6. The S-bend nozzle self-bleeding wall cooling infrared suppression structure according to any one of claims 1 to 5, characterized in that: The air bleed angle of the air bleed pipe ranges from 0 to 20 degrees, and the air bleed angle is the angle between the air inlet end of the air bleed pipe and the axial direction of the mixer.

7. A method for designing an infrared suppression structure of an S-bend nozzle self-bleeding wall cooling, the method being used to obtain the bleed angle of the infrared suppression structure of the S-bend nozzle self-bleeding wall cooling according to claim 6, characterized in that: include: According to the structural dimensions of the S-bend nozzle, a three-dimensional model of the S-bend nozzle including the air bleed hole, the air inlet hole and the air bleed pipe is constructed; Under the engine design operating conditions, the S-bend nozzle outlet wall temperature corresponding to different air bleed angles is obtained by simulation; According to the air entrainment angle and the corresponding wall temperature, a functional relationship between the air entrainment angle and the wall temperature is constructed; According to the required value of the wall temperature of the engine S-bend nozzle outlet, the functional relationship is used to analyze and obtain the corresponding analysis value of the bleed air angle.

8. The design method of the infrared suppression structure of the S-bend nozzle self-bleeding wall cooling according to claim 7 is characterized in that: The air entrainment angle ranges from 0 to 20°. If the air entrainment angle analysis value is greater than or equal to 20°, the air entrainment angle is 20°.

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