Adjustable stator blade in air inlet casing of aircraft engine and design method of adjustable stator blade

Abstract

The invention belongs to the technical field of aircraft engine air inlet casing design, and particularly relates to an adjustable stator blade in an aircraft engine air inlet casing and a design method thereof.The adjustable stator blade in the aircraft engine air inlet casing comprises a blade body, an upper journal and a lower journal, and the upper journal and the lower journal are connected to the blade body; the blade body comprises an inner bearing structure and an outer wave absorbing layer; the inner bearing structure is a plate-shaped structure; the outer wave-absorbing layer covers the outer side of the inner bearing structure and is made of a material with wave-absorbing capacity; the material with the wave-absorbing capability can be a composite material with the wave-absorbing capability or a wave-absorbing coating; the material types and thickness distributions of different positions of the outer wave-absorbing layer are different, so that the radar wave-absorbing capacities of different positions of the adjustable stator blade are different, the adjustable stator blade can be matched with tasks executed by an airplane, and radar waves with low detectability requirements are absorbed in a targeted mode.

Description

Technical Field

[0001] The present application belongs to the technical field of aircraft engine air intake casing design, and specifically relates to an adjustable stator blade in an aircraft engine air intake casing and a design method thereof. Background Art

[0002] The engine is the main power source of the aircraft and an important source of radar reflection. In order to reduce the detectability of the aircraft, the engine's air intake casing is usually designed, mainly using the following three technical solutions.

[0003] Option 1: The inner and outer flow channel surfaces of the engine air intake casing and the outer side of the support plate are coated with a radar wave absorbing coating.

[0004] Within the flight envelope, when the aircraft performs different tasks, the requirements for detectability vary and the radar bands they target are different. To ensure the aircraft's low detectability within the entire flight envelope, the radar-absorbing coating needs to be able to absorb radar waves in a wider band and also needs to meet requirements such as strength and bonding strength. The design and update are difficult, the price is high, and the engineering implementation is difficult. In addition, the radar-absorbing coating usually has a large density. Large-scale use will greatly increase the weight of the engine, reduce the engine inlet flow, affect the engine's aerodynamic performance, and reduce the engine thrust, affecting the engine's thrust-to-weight ratio.

[0005] Option 2: A wave-absorbing guide fluid capable of absorbing radar waves is arranged in the aircraft air intake duct at the front end of the engine air intake casing.

[0006] The waveguide fluid has a complex structure and is large in size and weight, which will cause a large loss in many key indicators such as engine weight, size, thrust, etc. In addition, the waveguide fluid is set at a certain axial distance from the front end of the engine, which affects the compact design of the engine and greatly increases the distance from the front end inspection and maintenance operation position of the engine to the fan's first-stage rotor, greatly increasing the difficulty of inspecting and maintaining the fan, and increasing the axial space required for engine installation. It not only affects the space utilization of the installed aircraft, but also seriously limits the versatility of the engine for different types of aircraft, and will greatly affect the quality of the flow field at the inlet of the aircraft engine, increase the aerodynamic loss of the engine, affect the thrust of the engine, and reduce the thrust-to-weight ratio of the engine.

[0007] Option 3: An S-curve air inlet coated with a radar-absorbing coating is added to the front end of the engine air intake casing, and the S-curve air inlet is used to repeatedly refract and absorb radar waves.

[0008] The S-curved air inlet is arranged at the front end of the engine air intake casing, and also has a large size and weight, which will cause a large loss of many key indicators such as engine weight, size, thrust, etc., affecting the compact design of the engine, and will greatly increase the distance from the front end inspection and maintenance operation position of the engine to the first-stage rotor of the fan, greatly increasing the difficulty of inspecting and maintaining the fan, and bringing about an increase in the axial space required for engine installation, which not only affects the space utilization of the installed aircraft, but also seriously limits the versatility of the engine for different types of aircraft, and due to the complex bending structure, it will seriously affect the flow field quality at the engine inlet, increase the engine aerodynamic loss, affect the engine thrust, and reduce the engine's thrust-to-weight ratio.

[0009] The above three technical solutions are fixed structure designs and cannot be adaptively adjusted to absorb radar waves of corresponding bands according to the missions performed by the aircraft. In order to ensure the low detectability requirements within the entire flight envelope of the aircraft, all possible radar bands and their requirements can only be taken into account as much as possible. This often results in over-design of detectability, such as thicker absorbing coatings, longer axial length of absorbing guide fluid, larger bending degree of S-bend inlet duct, etc., which further aggravates the technical problems.

[0010] This application is proposed in view of the above-mentioned technical defects. Summary of the invention

[0011] The purpose of the present application is to provide an adjustable stator blade in an aircraft engine air intake casing and a design method thereof, so as to overcome or alleviate at least one aspect of the known technical defects.

[0012] The technical solution of this application is: On the one hand, an adjustable stator blade in an air intake casing of an aircraft engine is provided, comprising a blade body, and an upper journal and a lower journal connected to the blade body; The blade body includes an inner load-bearing structure and an outer wave-absorbing layer; The internal load-bearing structure is a plate-like structure; The outer wave-absorbing layer is coated on the outer side of the inner bearing structure and is made of a material with wave-absorbing ability; The material with microwave absorption capability is a composite material with microwave absorption capability, or a microwave absorption coating; The material type and thickness distribution at different positions of the outer absorbing layer are different, so that the radar absorbing capabilities of different positions of the adjustable stator blades are different, so as to match the mission performed by the aircraft and specifically absorb radar waves with low detectability requirements.

[0013] Optionally, in the adjustable stator blades in the above-mentioned aircraft engine air intake casing, the internal load-bearing structure is made of fiber-reinforced composite materials, or made of lightweight metal materials.

[0014] Optionally, in the above-mentioned adjustable stator blades in the air intake casing of the aircraft engine, the upper journal and the lower journal are connected to the inner bearing structure.

[0015] Optionally, in the above-mentioned adjustable stator blades in the air intake casing of the aircraft engine, the upper journal and the lower journal are made of the same material as the inner bearing structure and are integrally formed on the inner bearing structure.

[0016] On the other hand, a method for designing adjustable stator blades in an aircraft engine air intake casing is provided, which is used to design the adjustable stator blades in the aircraft engine air intake casing, comprising: Step 1: Preliminary design of the blade profile and adjustment angle of the adjustable stator blade; Step 2: Analyze the low-observability requirements of the aircraft for various missions within the flight envelope, including the radar bands targeted by low-observability and the required degree; Step 3: Identify the adjustment angles of the adjustable stator blades when the aircraft performs various tasks, and then determine the corresponding low detectability requirements; Step 4: Design the material type and thickness distribution at different positions of the external absorbing layer according to the adjustment angle of the adjustable stator blades and the corresponding low detectability requirements; Step 5: Analyze the detectability of the adjustable stator blade adjustment angles under the whole machine condition and the corresponding engine operating conditions to see whether they meet the corresponding low detectability requirements; If there is a situation where the detectability of the adjustable stator blade adjustment angle under the engine operating condition does not meet the corresponding low detectability requirement, the adjustable stator blade profile and its adjustment angle are optimized, and steps three to five are repeated until the detectability of each adjustable stator blade adjustment angle under the engine operating condition meets the corresponding low detectability requirement.

[0017] This application has at least the following beneficial technical effects: The adjustable stator blades in the air intake casing of the engine disclosed in the above-mentioned embodiment and the design method thereof utilize the one-to-one correspondence between the missions performed by the aircraft within the flight envelope, the radar bands and requirements for its low detectability, the engine operating conditions, the adjustment angles of the adjustable stator blades in the air intake casing, and the reflection paths of the radar waves, and design the adjustable stator blades to have radar absorbing capabilities, and the radar absorbing capabilities at different positions are different, so that within the entire flight envelope, the radar waves required for low detectability can be absorbed in a targeted manner according to the missions performed by the aircraft, and the required degree of low detectability can be achieved, thereby reducing the requirements for the existing air intake casing related designs, avoiding over-design of detectability, and achieving the purpose of reducing the severity of related technical problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1It is a schematic diagram of the reflection path of radar waves when the adjustable stator blades in the air intake casing of an aircraft engine provided by an embodiment of the present application are at an open angle; Figure 2 It is a schematic diagram of the reflection path of radar waves when the adjustable stator blades in the air intake casing of an aircraft engine provided by an embodiment of the present application are at a closed angle; Figure 3 is a schematic diagram of adjustable stator blades in an aircraft engine air intake casing provided by an embodiment of the present application; Figure 4 is a schematic cross-sectional view of a blade body provided in an embodiment of the present application; Figure 5 It is a schematic diagram of a design method for adjustable stator blades in an aircraft engine air intake casing provided by an embodiment of the present application; in: 1- blade body; 2- upper journal; 3- lower journal; 11- internal load-bearing structure; 12- external wave-absorbing layer.

[0019] In order to better illustrate the present embodiment, some contents of the drawings may be omitted, enlarged or reduced, which is only used for illustrative purposes and should not be construed as limiting the present application. DETAILED DESCRIPTION

[0020] In order to make the technical solution and advantages of the present application clearer, the technical solution of the present application will be described in further detail in detail and in detail with reference to the accompanying drawings. It can be understood that the specific embodiments described here are only partial embodiments of the present application, which are only used to explain the present application, not to limit the present application. It should be noted that, for the convenience of description, only the parts related to the present application are shown in the accompanying drawings, and other related parts can refer to the general design.

[0021] In addition, unless otherwise defined, the technical terms or scientific terms used in the description of this application should be the common meanings understood by those skilled in the art in the field to which this application belongs. The term "include" used in the description of this application means that the concepts appearing before the term include the concepts listed after the term and their equivalents, without excluding other related concepts.

[0022] In addition, the words indicating orientation used in the description of this application are only used to indicate relative directions or positional relationships. When the absolute position of the object being described changes, its relative positional relationship may also change accordingly. It should also be noted that, unless otherwise clearly specified and limited, the words "installation", "connection" and other similar words used in the description of this application should be understood in a broad sense. For example, the connection can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Technical personnel in the field can understand its specific meaning in this application according to the specific circumstances.

[0023] Within the flight envelope, when an aircraft performs different tasks, its low detectability targets different radar bands, and the requirements for detectability are different. For example, when an aircraft performs a cruising mission, its low detectability mainly targets radar waves in the low-frequency band, and the requirements for low detectability are relatively high; when performing maneuvering missions, its detectability mainly targets radar waves in the high-frequency band, and the requirements for low detectability are relatively low; and when performing take-off and landing missions, the radar bands targeted by low detectability and the requirements for low detectability are also different.

[0024] When an aircraft performs different tasks, it needs to match different engine operating conditions. For example, when an aircraft performs a cruising mission, the required thrust is smaller, and the engine only needs to work at a lower operating condition; when the aircraft performs a maneuvering mission, the required thrust is larger, and the engine needs to work at a higher operating condition.

[0025] The engine air intake casing is equipped with adjustable stator blades. The angle of the adjustable stator blades is adjusted accordingly according to the engine working conditions to meet the engine's requirements for inlet flow under different working conditions. When the engine is working at a lower working condition, the inlet flow requirement is lower, and the adjustable stator blades are adjusted to a slightly closed angle; when the engine is working at a higher working condition, the inlet flow requirement is higher, and the adjustable stator blades are adjusted to a slightly open angle. When the adjustable stator blades are at different opening angles, the reflection paths of radar waves are different in conjunction with the support plate in the air intake casing and the electromagnetic reflection surface in the engine, such as Figure 1-Figure 2 As shown, the blade shape of the adjustable stator blade will also affect the reflection path of the radar wave, and the blade shape of the adjustable stator blade is different, and the angle that needs to be opened under different engine working conditions is also different.

[0026] From the above, it can be seen that within the flight envelope, the missions performed by the aircraft, the radar bands and requirements for low detectability, and the engine operating conditions, the adjustment angles of the adjustable stator blades in the air intake casing, and the reflection paths of the radar waves have a one-to-one correspondence. In this way, under the condition that the adjustable stator blade profile is determined, the adjustable stator blades can be designed to have radar absorbing capabilities, and the radar absorbing capabilities at different positions are different. In this way, within the entire flight envelope, according to the missions performed by the aircraft, targeted adjustments can be made to absorb radar waves with low detectability requirements, and the degree of low detectability requirements can be achieved, thereby reducing the requirements for the existing air intake casing related designs, avoiding over-design of detectability, and thus reducing the severity of related technical problems.

[0027] Based on the above embodiments of the present application, there is provided an adjustable stator blade in an air intake casing of an aircraft engine, such as Figure 3 As shown, it includes a blade body 1 , and an upper journal 2 and a lower journal 3 connected to the blade body 1 .

[0028] The blade body 1 includes an inner bearing structure 11 and an outer absorbing layer 12. Figure 4 shown.

[0029] The internal load-bearing structure 11 is a plate-like structure, made of fiber-reinforced composite materials with high specific strength and high specific stiffness, such as carbon fiber reinforced composite materials, or made of lightweight metal materials, such as T800-grade carbon fiber reinforced bismaleimide resin-based composite materials, or TC4 titanium alloy. It has a high load-bearing capacity, so as to be able to effectively transmit the aerodynamic loads borne by the adjustable stator blades, maintain the shape of the adjustable stator blades, and avoid serious deformation or damage of the adjustable stator blades under aerodynamic loads.

[0030] The upper journal 2 and the lower journal 3 can be connected to the inner bearing structure 11 , and can be made of the same material as the inner bearing structure 11 , and can be integrally formed on the inner bearing structure 11 .

[0031] The outer wave absorbing layer 12 is coated on the outer side of the inner bearing structure 11 and is made of a material having wave absorbing capability.

[0032] The material with wave-absorbing ability can be a composite material with wave-absorbing ability, such as a glass fiber reinforced resin-based composite material with added carbonyl iron powder wave-absorbing particles, or a wave-absorbing coating, such as a wave-absorbing coating such as ferrite, barium titanate, etc.

[0033] The material type and thickness distribution at different positions of the outer absorbing layer 12 are different, so that the radar absorbing capabilities of different positions of the adjustable stator blades are different, so as to match the mission performed by the aircraft, specifically absorb radar waves with low detectability requirements, and achieve the degree of low detectability requirements.

[0034] In order to quickly design an adjustable stator blade that meets the use requirements, the present application provides the following design method for the adjustable stator blade in the aircraft engine air intake casing disclosed in the above embodiment, such as Figure 5 shown.

[0035] Step 1: Make a preliminary design of the adjustable stator blade profile and its adjustment angle.

[0036] The preliminary design of the adjustable stator blade profile and adjustment angle provides an initial solution for the adjustable stator blade profile and the use angle in various engine working conditions. The design can refer to the existing conventional adjustable stator blade profile and adjustment angle design method.

[0037] Step 2: Analyze the low detectability requirements of the aircraft for various missions within the flight envelope, including the radar bands targeted by low detectability and the required degree.

[0038] The requirement for low detectability mentioned herein may mainly refer to the requirement for forward low detectability of the engine.

[0039] Step 3: Identify the adjustment angles of the adjustable stator blades when the aircraft performs various tasks, and then determine the corresponding low detectability requirements.

[0040] Step 4: According to the adjustment angle of the adjustable stator blades and the corresponding low detectability requirements, the material type and thickness distribution at different positions of the external absorbing layer are designed.

[0041] When the adjustment angle of the adjustable stator blades is determined, the reflection path of the radar wave is also determined accordingly. Therefore, the wave absorbing enhancement design can be concentrated on the corresponding radar band targeting low detectability in the reflection area, and the corresponding absorbing materials can be selected and the material thickness can be increased to meet the corresponding low detectability requirements.

[0042] Since the purpose of designing this type of adjustable stator blades is to reduce the requirements for the existing air intake casing related design, avoid over-design of detectability, and reduce the severity of related technical problems, we can focus on the situation when the low detectability requirements are high, and design the material type and thickness distribution at different positions of the external absorbing layer.

[0043] Step 5: Analyze the detectability of the adjustable stator blade adjustment angles under the whole machine conditions corresponding to the engine operating conditions to see whether they meet the corresponding low detectability requirements. The specific analysis can be carried out by experimental or simulation methods.

[0044] If there is a situation where the detectability of the adjustable stator blade adjustment angle under the engine operating condition does not meet the corresponding low detectability requirement, identify the key factors that do not meet the corresponding low detectability requirement, optimize the adjustable stator blade profile and its adjustment angle, and repeat steps three to five until the detectability of each adjustable stator blade adjustment angle under the engine operating condition meets the corresponding low detectability requirement.

[0045] The adjustable stator blades in the air intake casing of the engine disclosed in the above-mentioned embodiment and the design method thereof utilize the one-to-one correspondence between the missions performed by the aircraft within the flight envelope, the radar bands and requirements for its low detectability, the engine operating conditions, the adjustment angles of the adjustable stator blades in the air intake casing, and the reflection paths of the radar waves, and design the adjustable stator blades to have radar absorbing capabilities, and the radar absorbing capabilities at different positions are different, so that within the entire flight envelope, the radar waves required for low detectability can be absorbed in a targeted manner according to the missions performed by the aircraft, and the required degree of low detectability can be achieved, thereby reducing the requirements for the existing air intake casing related designs, avoiding over-design of detectability, and achieving the purpose of reducing the severity of related technical problems.

[0046] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the scope of protection of the present application.

Claims

1. An adjustable stator blade in an aircraft engine air intake casing, characterized in that: It comprises a blade body (1), and an upper journal (2) and a lower journal (3) connected to the blade body (1); The blade body (1) comprises an inner load-bearing structure (11) and an outer wave-absorbing layer (12); The inner bearing structure (11) is a plate-shaped structure; The outer wave absorbing layer (12) is coated on the outer side of the inner bearing structure (11) and is made of a material having wave absorbing capability; The material with microwave absorption capability is a composite material with microwave absorption capability, or a microwave absorption coating; The material type and thickness distribution of the outer absorbing layer (12) at different positions are different, so that the radar absorbing capabilities of the adjustable stator blades at different positions are different, so as to match the mission performed by the aircraft and absorb radar waves with low detectability requirements in a targeted manner.

2. The adjustable stator blade in the air intake casing of an aircraft engine according to claim 1, characterized in that: The inner load-bearing structure (11) is made of fiber-reinforced composite material or lightweight metal material.

3. The adjustable stator blade in the air intake casing of an aircraft engine according to claim 2, characterized in that: The upper journal (2) and the lower journal (3) are connected to the inner bearing structure (11).

4. The adjustable stator blade in the air intake casing of an aircraft engine according to claim 3, characterized in that: The upper journal (2) and the lower journal (3) are made of the same material as the inner bearing structure (11) and are integrally formed on the inner bearing structure (11).

5. A method for designing adjustable stator blades in an aircraft engine air intake casing, used for designing the adjustable stator blades in an aircraft engine air intake casing according to claim 4, characterized in that: include: Step 1: Preliminary design of the blade profile and adjustment angle of the adjustable stator blade; Step 2: Analyze the low-observability requirements of the aircraft for various missions within the flight envelope, including the radar bands targeted by low-observability and the required degree; Step 3: Identify the adjustment angle of the adjustable stator blades when the aircraft performs various tasks, and then determine the corresponding low detectability requirements; Step 4: Design the material type and thickness distribution at different positions of the external absorbing layer according to the adjustment angle of the adjustable stator blades and the corresponding low detectability requirements; Step 5: Analyze the detectability of the adjustable stator blade adjustment angles under the whole machine condition and the corresponding engine operating conditions to see whether they meet the corresponding low detectability requirements; If there is a situation where the detectability of the adjustable stator blade adjustment angle under the engine operating condition does not meet the corresponding low detectability requirement, the adjustable stator blade profile and its adjustment angle are optimized, and steps three to five are repeated until the detectability of each adjustable stator blade adjustment angle under the engine operating condition meets the corresponding low detectability requirement.

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