Auxiliary power unit air bleed structure and aircraft engine

Abstract

The present application discloses an air bleed structure for an auxiliary power unit and an aircraft engine. The air bleed structure for the auxiliary power unit includes: a casing and a flame tube. The casing is a double-layer shell structure. The casing includes an inner shell and an outer shell located on the outer periphery of the inner shell. A casing cavity is formed between the outer shell and the inner shell. Inner shell air bleed holes are provided on the inner shell, and outer shell air bleed holes are provided on the outer shell. The outer shell air bleed holes supply air to the main engine air supply channel through an air bleed pipe. The flame tube is located inside the inner shell. The outer wall of the flame tube is provided with a flame tube air inlet hole. An inlet flow passage is formed between the inner shell and the outer wall of the flame tube. The angle between the opening direction of the inner shell air bleed hole and the inlet direction of the inlet flow passage is not greater than 75. ° The aircraft engine includes the above-mentioned air bleed structure. The present application is used to solve the technical problem in the prior art that the combustion performance of the air bleed structure is deteriorated and strong excitation is generated due to the uneven airflow of the air bleed structure of the engine auxiliary power unit.

Description

Technical Field

[0001] The present application relates to the technical field of aero-engines, and in particular to an air bleed structure of an auxiliary power unit and an aero-engine. Background Art

[0002] The start of an aircraft engine first requires the help of external force to achieve initial operation and help establish a continuous working state of the airflow in the flow channel. In high-thrust, high-power aircraft engines, this external force is usually provided by compressed air to drive the air turbine starter to rotate. The auxiliary power unit is a device that provides compressed air. It is a small gas turbine engine. Its use not only meets the needs of rapid start-up of high-thrust / power engines, but also reduces the aircraft's dependence on ground support equipment. At the same time, it also increases safety during flight. It has become one of the indispensable airborne equipment on modern aircraft.

[0003] Currently, commonly used auxiliary power units include two types: core compressor output compressed air and load compressor output compressed air. For the auxiliary power unit with core compressor output compressed air, it draws part of the compressed air from the combustion chamber flow channel to provide bleed air to the air turbine starter to start the main engine (on the ground and in the air). For this type of auxiliary power unit, the bleed air structure design can effectively change its bleed air distribution, which has a significant impact on the performance of the auxiliary power unit.

[0004] At present, there are few designs for air bleed structures, and annular seam air bleed structures are often used, such as Figure 2 As shown. The airflow enters the combustion chamber casing from the compressor at the left end, and then is divided into two parts. One part enters the bleed air cavity through the bleed air gap between the bleed air baffle and the casing, and then provides bleed air to the main engine from the main engine air supply channel; the other part enters the flame tube through the opening on the flame tube for combustion. In this annular slit bleed air method, since the main engine air supply channel is only located at a specific circumferential position, its bleed air flow is inevitably uneven in the circumferential direction, which in turn causes the airflow entering the flame tube to participate in combustion to be uneven in the circumferential direction, which will lead to deterioration of combustion performance and reduction in practical efficiency. In addition, the outer ring of the bleed air baffle of this structure cannot be fixed, and the bleed air baffle will produce strong excitation under the influence of uneven airflow, which is easy to cause failure modes such as cracks.

[0005] Application Contents

[0006] Therefore, the present application aims to solve the technical problems in the prior art of deteriorating the combustion performance of the air bleed structure and generating strong vibrations due to the uneven airflow of the air bleed structure of the engine auxiliary power unit, thereby providing an air bleed structure for an auxiliary power unit and an aircraft engine.

[0007] In order to solve the above technical problems, the technical solution of the present application is as follows: an air bleed structure of an auxiliary power unit, comprising:

[0008] The casing is a double-layer shell structure, the casing comprises an inner shell and an outer shell located at the outer periphery of the inner shell, and a casing inner cavity is formed between the outer shell and the inner shell; the inner shell is provided with an inner shell air bleed hole, the outer shell is provided with an outer shell air bleed hole, and the outer shell air bleed hole supplies air to the main engine air supply channel through an air bleed pipe;

[0009] The flame tube is located inside the inner shell, the outer wall of the flame tube is provided with a flame tube air inlet hole, an inlet flow channel is formed between the inner shell and the outer wall of the flame tube, and the angle between the opening direction of the inner shell air inlet hole and the inlet direction of the inlet flow channel is not greater than 75 ° .

[0010] Preferably, the air intake direction of the air intake channel is parallel to the central axis direction of the casing, and the angle between the opening direction of the air intake hole of the inner shell and the central axis of the casing is 15 ° Up to 75 ° .

[0011] Preferably, the inner casing is provided with a plurality of air intake holes, and the inner casing air intake holes are radially distributed in a plurality of rows on the inner casing along the central axis direction of the casing, and the plurality of inner casing air intake holes in the same row are evenly distributed along the circumference of the inner casing.

[0012] Preferably, the outer shell is provided with a plurality of air intake holes, and the plurality of air intake holes of the outer shell are evenly distributed along the circumference of the outer shell.

[0013] Preferably, the diameter of the air ducting holes of the inner shell is 0.5 mm to 2 mm, and the diameter of the air ducting holes of the outer shell is larger than the diameter of the air ducting holes of the inner shell.

[0014] Preferably, a diffuser is provided at the air inlet end of the casing, and a circumferentially continuous inlet flow passage is formed between the diffuser and the inner casing.

[0015] Preferably, one end of the casing away from the diffuser is inclined toward the central axis of the casing to form a reduced diameter section, the outer shell air bleed holes are arranged on the outer shell in the reduced diameter section, and the air bleed pipe is connected to the outer wall of the outer shell in the reduced diameter section.

[0016] Preferably, the inner shell and the outer shell in the reduced diameter section have the same inclination direction.

[0017] Preferably, the air duct is a variable-section annular vortex structure, and the diameter of the air duct at one end close to the air duct outlet is larger than the diameter of the air duct at one end away from the air duct outlet.

[0018] There is also provided an aircraft engine comprising the air bleed structure of the auxiliary power unit described in any one of the above.

[0019] The technical solution of this application has the following advantages:

[0020] 1. In the present invention, the inner shell air bleed holes of the inner shell can effectively reduce the excitation effect caused by the initial vibration and unevenness of the bleed air, thereby improving the service life of the auxiliary power unit; the inner shell blocks and guides the airflow, and compared with the existing air bleed baffle, the inner shell has a better airflow guidance effect, and the structure of the inner shell is more stable and not easily affected by the impact of the airflow to generate excitation, thereby further improving the working stability and service life of the air bleed structure of the auxiliary power unit.

[0021] 2. The angle between the opening direction of the inner shell air intake hole and the central axis of the casing is 15 ° To 75°, thereby ensuring that the direction of the bleed air flow is roughly consistent with the direction of the bleed air holes of the inner shell, so that the bleed air flow can flow along the bleed air holes of the inner shell, thereby ensuring the smoothness of the bleed air flow, and reducing the intensity of the excitation generated by the air flow impacting the inner shell, so that the air flow can enter the bleed air duct more smoothly.

[0022] 3. The inclined inner shell can better resist the impact of airflow and also have a more gentle drainage effect on the airflow.

[0023] 4. Improve the air distribution of the air bleed structure of the auxiliary power unit by adjusting the aperture size, distribution and number of the air bleed holes, so that the combustion in the flame tube can be organized more reasonably, the combustion efficiency can be improved and a better outlet temperature distribution can be obtained, so as to improve the shaft power output efficiency of the auxiliary power unit and the life of the turbine blades. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 It is a schematic diagram of the overall structure of an air bleed structure of an auxiliary power device in an embodiment of the present application;

[0026] Figure 2 It is a schematic diagram of the bleed air structure of the auxiliary power unit in the prior art;

[0027] Figure 3 It is a schematic diagram of the overall structure of the casing in the embodiment of the present application;

[0028] Figure 4 Schematic diagram of the overall structure of the outer shell in the embodiment of the present application.

[0029] Explanation of the reference numerals: 1. outer shell; 1-1. air bleed hole of outer shell; 2. inner shell; 2-1. air bleed hole of inner shell; 3. air bleed pipe; 3-1. outlet end of air bleed pipe; 4. flame tube; 4-1. air inlet hole of flame tube; 5. diffuser; 6. buffer flow channel; 7. inner cavity of casing; 8. air inlet flow channel. DETAILED DESCRIPTION

[0030] The technical solution of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0031] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0032] Example 1

[0033] The embodiment provides an air bleed structure for an auxiliary power device, including a casing and a flame tube 4.

[0034] The casing is a double-layer shell structure. Figure 1 and Figure 3 As shown, the casing includes an integrated inner casing 2 and an outer casing 1 , wherein the outer casing 1 is located at the periphery of the inner casing 2 , and there is a hollow area between the outer casing 1 and the inner casing 2 , which is the casing inner cavity 7 , and airflow can flow in the casing inner cavity 7 .

[0035] An inner shell air bleed hole 2-1 is opened on the inner shell 2, and an outer shell air bleed hole 1-1 is opened on the outer shell 1. The inner shell air bleed hole 2-1 is connected with the outer shell air bleed hole 1-1 through the casing inner cavity 7. The outer shell air bleed hole 1-1 supplies air to the main engine air supply channel through the air bleed pipe 3. The end of the air bleed pipe 3 connected to the main engine is the air bleed pipe outlet end 3-1.

[0036] The flame tube 4 is located inside the inner shell 2. The outer wall of the flame tube 4 is provided with a flame tube air inlet hole 4-1. An inlet flow passage 8 is formed between the inner shell 2 and the outer wall of the flame tube 4. The inlet flow passage 8 is connected to the casing cavity 7 through the inner shell air inlet hole 2-1.

[0037] like Figure 1 As shown, the right end of the intake air channel 8 is the intake end, the left end of the intake air channel 8 is the outlet end, the flow direction of the air flow in the intake air channel 8 is from right to left, the opening direction of the air intake hole 2-1 of the inner shell is substantially the same as the intake direction of the intake air channel 8, the opening direction of the air intake hole 2-1 of the inner shell and the intake direction of the intake air channel 8 are at a certain inclination angle, and the inclination range is not more than 75 ° .

[0038] The working process of the air bleed structure of the auxiliary power unit provided in this embodiment is as follows: air flow is introduced from the air intake end of the air intake duct 8, and the air flow flows from right to left. A part of the air flow passes through the air intake hole 2-1 of the inner shell and enters the inner cavity 7 of the casing. The air flow then passes through the air intake hole 1-1 of the outer shell and enters the air bleed pipe 3. Finally, air is supplied to the main engine air supply channel through the air bleed pipe 3, and finally the purpose of air intake for the main engine is achieved; the other part of the air flow enters the flame tube 4 through the flame tube air intake hole 4-1 to complete combustion or mixing.

[0039] It should be noted that, for the airflow passing through the inner casing air bleed hole 2-1, when the airflow passes through the inner casing air bleed hole 2-1, since the inner casing 2 and the outer casing 1 are integrated, and the opening angle of the inner casing air bleed hole 2-1 is consistent with the airflow direction, the airflow is evenly dispersed by the inner casing air bleed hole 2-1 after passing through the inner casing air bleed hole 2-1, avoiding the disorderly flow of the airflow in the casing, increasing the orderliness of the airflow, and the inner casing air bleed hole 2-1 can effectively reduce the excitation effect caused by the initial vibration and unevenness of the bleed air, avoiding the strong excitation inside the casing causing damage to the parts, and helping to improve the service life of the auxiliary power unit. The inner casing 2 blocks and guides the airflow. Compared with the existing bleed baffle, the inner casing 2 has a better effect of guiding the airflow, and the inner casing 2 is not easily damaged by the airflow. For the airflow entering the flame tube 4, it is the residual air volume after the initial airflow passes through the inner casing air bleed hole 2-1. Since the uniformity of the airflow distribution through the air inlet hole 2-1 of the inner shell is improved, the distribution of the remaining air volume of the initial airflow entering the combustion organization area through the flame tube air inlet hole 4-1 is also improved. The oil-gas ratio in the flame tube 4 is uniform, the combustion organization in the flame tube 4 is reasonable, and the fuel combustion is more complete, thereby improving the combustion efficiency of the flame tube 4 of the auxiliary power unit and improving the outlet temperature distribution. The improvement of the combustion efficiency can improve the output efficiency of the shaft power of the auxiliary power unit; the improvement of the outlet temperature distribution can further increase the life of the turbine blades that output the shaft power. This embodiment can ultimately improve the practical efficiency and service life of the auxiliary power unit.

[0040] Example 2

[0041] This embodiment is a further improvement of embodiment 1. Figure 1 As shown, a diffuser 5 is provided at the air inlet end of the casing, and a circumferentially continuous air inlet passage 8 is formed between the diffuser 5 and the inner casing 2. When the airflow passes through the diffuser 5, the diffuser 5 plays a role of pressurizing the airflow and initially guiding the airflow, so that the airflow can enter the air inlet passage 8 more smoothly.

[0042] The central axes of the outer shell 1 and the inner shell 2 of the casing are both horizontal lines, the air intake direction of the air intake channel 8 is also horizontal, and the angle between the opening direction of the air intake hole 2-1 of the inner shell and the central axis of the casing is 15 ° Up to 75 ° After many experiments, it was found that setting the opening direction of the air intake hole 2-1 of the inner shell in the range of 15°-75° can effectively reduce the vibration effect of the airflow inside the casing.

[0043] like Figure 3 As shown, a plurality of inner casing air intake holes 2-1 are provided on the inner casing 2, and the inner casing air intake holes 2-1 are radially distributed in a plurality of rows on the inner casing 2 along the central axis direction of the casing (i.e. Figure 3 In the embodiment, multiple groups of inner shell air inlet holes 2-1 are arranged on the left and right sides of the inner shell 2, and multiple inner shell air inlet holes 2-1 in the same row are evenly distributed along the circumference of the inner shell 2. By arranging multiple groups of inner shell air inlet holes 2-1 in an orderly manner at intervals, the airflow entering the inner cavity 7 of the casing through the inner shell air inlet holes 2-1 can be made more uniform, which helps to further improve the uniformity and stability of the airflow when it circulates inside the casing, thereby further reducing the excitation effect of the airflow when it circulates inside the casing.

[0044] The aperture size of the inner shell air bleed hole 2-1 is 0.5mm to 2mm, the number of single-ring inner shell air bleed holes 2-1 ranges from 100 to 360, and the inner shell air bleed holes 2-1 are radially distributed in 5 to 15 rows. The aperture of the outer shell air bleed hole 1-1 is larger than the aperture of the inner shell air bleed hole 2-1. Through multiple experiments, it was found that when the aperture of the inner shell air bleed hole 2-1 is adjusted within the range of 0.5mm to 2mm, the exciting effect of the casing changes significantly with the change of the aperture. When the aperture is less than 0.5mm or greater than 2mm, the exciting effect of the casing does not change significantly with the change of the aperture. Therefore, setting the diameter of the inner shell air bleed hole 2-1 to 0.5mm to 2mm and adjusting the aperture size within this range will help to achieve better and more significant improvements.

[0045] There are multiple air bleed holes 1-1 in the outer shell, and the multiple air bleed holes 1-1 in the outer shell are evenly distributed along the circumference of the outer shell 1 and are arranged near the left end surface. An annular buffer flow channel 6 is arranged near the left end surface of the outer shell 1, and the buffer flow channel 6 is connected with the inner cavity 7 of the casing through the air bleed holes 1-1 of the outer shell. The air bleed holes 1-1 of the outer shell near the air bleed pipe 3 are larger than the air bleed holes 1-1 of the outer shell far away from the air bleed pipe 3. The air bleed pipe 3 is in communication with the inner cavity 7 of the casing through the buffer flow channel 6 and the air bleed holes 1-1 of the outer shell. The air bleed pipe 3 is a variable cross-section annular vortex structure, and the diameter of the end of the air bleed pipe 3 near the outlet end 3-1 of the air bleed pipe is larger than the diameter of the end far away from the outlet end 3-1 of the air bleed pipe. The pressure difference on both sides of the air bleed hole 1-1 of the outer shell near the air bleed pipe 3 is relatively large. The corresponding size of the aperture is matched by the size of the pressure difference at different positions, so that the air intake of the air bleed holes 1-1 of the outer shell at each position is relatively uniform, and the uniformity of the air bleed distribution is greatly improved.

[0046] Example 3

[0047] The present embodiment provides an aircraft engine, including the air bleed structure of the auxiliary power unit provided in Embodiment 1 or Embodiment 2. The air bleed structure of the auxiliary power unit provided in Embodiment 1 or Embodiment 2 is used to bleed air for the main engine, so that the aircraft engine provided in the present embodiment not only meets the demand for rapid starting of a high-thrust / high-power engine, but also reduces the aircraft's dependence on ground support equipment, while also increasing safety during flight.

[0048] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection created by this application.

Claims

1. An air bleed structure for an auxiliary power unit, characterized in that: include: The casing is a double-layer shell structure, comprising an inner shell (2) and an outer shell (1) located on the outer periphery of the inner shell (2), a casing inner cavity (7) being formed between the outer shell (1) and the inner shell (2); an inner shell air bleed hole (2-1) is provided on the inner shell (2), an outer shell air bleed hole (1-1) is provided on the outer shell (1), and the outer shell air bleed hole (1-1) supplies air to a main engine air supply channel through an air bleed pipe (3); A flame tube (4) is located inside the inner shell, the outer wall of the flame tube (4) is provided with a flame tube air inlet hole (4-1), an air inlet passage (8) is formed between the inner shell (2) and the outer wall of the flame tube (4), and the angle between the opening direction of the air inlet hole (2-1) of the inner shell and the air inlet direction of the air inlet passage (8) is not greater than 75°; A diffuser (5) is provided at the air inlet end of the casing, and a circumferentially continuous air inlet flow passage (8) is formed between the diffuser (5) and the inner casing (2); one end of the casing away from the diffuser (5) is inclined toward the central axis of the casing to form a reduced diameter section, the outer casing air bleed hole (1-1) is provided on the outer casing (1) in the reduced diameter section, and the air bleed pipe (3) is connected to the outer wall of the outer casing (1) in the reduced diameter section; the inner casing (2) and the outer casing (1) in the reduced diameter section have the same inclination direction.

2. The air bleed structure of the auxiliary power unit according to claim 1, characterized in that: The air intake direction of the air intake channel (8) is parallel to the central axis direction of the casing, and the angle between the opening direction of the air intake hole (2-1) of the inner casing and the central axis of the casing is 15° to 75°.

3. The air bleed structure of the auxiliary power unit according to claim 1, characterized in that: The inner casing air intake holes (2-1) are provided with a plurality of them, the inner casing air intake holes (2-1) are radially distributed in a plurality of rows on the inner casing (2) along the central axis direction of the casing, and the plurality of inner casing air intake holes (2-1) in the same row are evenly distributed along the circumference of the inner casing (2).

4. The air bleed structure of the auxiliary power unit according to claim 1, characterized in that: The outer shell is provided with a plurality of air intake holes (1-1), and the plurality of air intake holes (1-1) are evenly distributed along the circumference of the outer shell (1).

5. The air bleed structure of the auxiliary power unit according to claim 1, characterized in that: The aperture size of the air intake hole (2-1) of the inner shell is 0.5 mm to 2 mm, and the aperture size of the air intake hole (1-1) of the outer shell is larger than the aperture size of the air intake hole (2-1) of the inner shell.

6. The air bleed structure of the auxiliary power unit according to claim 1, characterized in that: The air bleed pipe (3) is a variable cross-section annular vortex structure, and the diameter of the air bleed pipe (3) at one end close to the air bleed pipe outlet end (3-1) is larger than the diameter of the end far from the air bleed pipe outlet end (3-1).

7. An aircraft engine, characterized in that: An air bleed structure for an auxiliary power unit comprising any one of claims 1-6.

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