Design method of telescopic air inlet channel, telescopic air inlet channel and aircraft

Abstract

The invention relates to the technical field of aircraft air inlet channel design, and discloses a design method of a telescopic air inlet channel, an air inlet of the telescopic air inlet channel stretches out during working and retracts during non-working, and the design method comprises the steps that L0, R0 and S0 are determined according to L, S and R; according to L0, R0 and S0, an initial inner flow channel molded surface after the telescopic air inlet channel extends out is designed; performing more than one optimization adjustment on the molded surface of the inner flow channel, comparing a plurality of total pressure recovery coefficients sigma 0 after the telescopic air inlet channel extends out under the condition of different Mach numbers with a plurality of sigma correspondingly required for operation of the engine one by one after each optimization adjustment until each sigma 0 is greater than or equal to the corresponding sigma, and determining that the telescopic air inlet channel is qualified. According to the design method of the telescopic air inlet channel, the telescopic air inlet channel and the aircraft, the layout of the air inlet channel can be folded and unfolded according to different working states of the engine, and the requirement of the air inlet channel for not occupying the overall size of the aircraft and the requirement for the total pressure recovery coefficient are considered.

Description

Technical Field

[0001] This invention relates to the field of aircraft air intake design technology, specifically to a design method for a telescopic air intake, a telescopic air intake, and an aircraft. Background Technology

[0002] Currently, air-breathing engines for aircraft rely on atmospheric oxygen as an oxidizer for combustion. They cannot operate independently in an oxygen-free environment and primarily depend on actively drawing in atmospheric oxygen during flight. The air intake is a key component of air-breathing engines, responsible for efficiently capturing and delivering external air into the engine to provide the oxidizer (oxygen) for combustion. Its design directly affects the engine's thrust, efficiency, and stability, playing a crucial role, especially during high-speed flight.

[0003] In related technologies, subsonic air intakes generally take the form of pitot-type intakes, S-curve intakes, and embedded intakes. The pitot-type intake is essentially an expanding channel that slightly converges at the intake opening, with a smooth lip. It is commonly found on passenger and transport aircraft, and is installed in series with the turbofan engine (air-breathing engines are classified according to their operating principle into turbojet engines, turbofan engines, ramjet engines, and scramjet engines), fixedly mounted on both sides of the aircraft. The pitot-type intake has a simple structure and is easy to maintain. The S-curve intake is often combined with DSI (Diverterless Supersonic Inlet) technology to form an internal compression section. The curved flow path shields the engine, preventing direct radar detection. Embedded intakes, because their intake openings are completely integrated into the fuselage, are significantly affected by the boundary layer on the fuselage surface and are not directly impacted by incoming airflow.

[0004] However, both the Pitot-type air intake and the S-curve air intake increase the overall size of the aircraft. It is precisely the size occupied by the air intake that makes the aircraft unsuitable for use in some special scenarios (such as the aircraft landing on an unofficial runway). The embedded air intake has its air intake completely integrated into the fuselage and does not occupy the overall size of the aircraft, but its total pressure recovery coefficient is too low. Summary of the Invention

[0005] This application provides a design method for a retractable air intake, a retractable air intake, and an aircraft. The air intake layout can be extended or retracted according to different engine operating states, taking into account the requirement that the air intake does not occupy the overall size of the aircraft and its total pressure recovery coefficient requirement.

[0006] In a first aspect, embodiments of this application provide a design method for a telescopic air intake, wherein the air intake port of the telescopic air intake extends during operation and retracts when not in operation. The design method includes the following steps: Based on the length L of the section of the fuselage occupied by the air intake of the same type of aircraft, the cross-sectional area S of the air intake of the air intake, and the known radius R of the front air intake port of the engine, the design length L0 of the lower fuselage port of the telescopic air intake, the design radius R0 of the rear port of the telescopic air intake, and the cross-sectional area S0 of the rear air intake port of the telescopic air intake are determined. Based on L0, R0, and S0, design the initial internal flow channel profile after the telescopic intake extends; The internal flow channel profile is optimized and adjusted more than once. Based on the total pressure recovery coefficient σ required for the engine to work under different Mach number conditions, after each optimization and adjustment, the multiple total pressure recovery coefficients σ0 after the telescopic air intake is extended under different Mach number conditions are compared with the multiple σ required for the engine to work, until each σ0 is greater than or equal to the corresponding σ, and the telescopic air intake is qualified.

[0007] In conjunction with the first aspect, in one implementation, determining L0, R0, and S0 based on L, S, and R includes: R0=R, L0=L×w1, S0=S×w2; Where w1 and w2 are set weighting coefficients, where w1≤1 and 0.8≤w2≤1.2.

[0008] In conjunction with the first aspect, in one embodiment, the initial internal flow channel profile of the telescopic intake after extension is designed according to L0, R0, and S0, comprising: The telescopic air intake is divided into an internal fuselage structure and a telescopic cover. The surface of the internal fuselage structure above the lower port is set as a quarter-circle arc. The surface of the telescopic cover below the lower port is inclined and guided to the rear port of the internal fuselage structure, ensuring that the telescopic cover can extend and retract relative to the internal fuselage structure and ensuring the three dimensions L0, R0 and S0.

[0009] In conjunction with the first aspect, in one implementation method, the inner flow channel profile is optimized and adjusted more than once, including: Each optimization adjustment involves adjusting the inner flow channel profile of the intake duct based on the distribution of the airflow streamlines, so that the inner flow channel profile closely matches the airflow streamlines.

[0010] In conjunction with the first aspect, in one embodiment, the distribution of the airflow streamlines in the internal flow channel is obtained through CFD simulation or wind tunnel test simulation.

[0011] In conjunction with the first aspect, in one implementation, each of the Mach number conditions corresponds to a total pressure recovery coefficient σ0 and a total pressure recovery coefficient requirement value σ; The internal flow channel profile is optimized and adjusted more than once, including: The distribution of the airflow streamlines in the inner flow channel is obtained, and the inner flow channel profile of the intake is adjusted to make the inner flow channel profile close to the airflow streamlines, thus obtaining the adjusted inner flow channel profile. Obtain multiple total pressure recovery coefficients σ0 of the telescopic intake after the adjusted internal flow channel profile is extended under different Mach numbers, and compare them one by one with the multiple total pressure recovery coefficient requirements σ required for engine operation; if each σ0 is greater than or equal to the corresponding σ, the telescopic intake is qualified; if any σ0 is less than the corresponding σ, the telescopic intake is unqualified, and return to obtain the distribution of the airflow streamline in the internal flow channel and adjust the internal flow channel profile until the telescopic intake is qualified.

[0012] In conjunction with the first aspect, in one embodiment, the telescopic air intake is divided into an internal fuselage structure and a telescopic cover, wherein the inner wall length of the lower port of the internal fuselage structure is equal to L0, and the inner wall radius of the rear port of the internal fuselage structure is R0.

[0013] In conjunction with the first aspect, in one embodiment, the total pressure recovery coefficient σ0 of an inner flow channel profile of the telescopic air intake is 0.927, 0.966, 0.975 and 0.986 respectively under different Mach number conditions Ma of 0.6, 0.5, 0.4 and 0.25, and the corresponding total pressure recovery coefficient required values ​​σ are 0.91, 0.94, 0.95 and 0.96 respectively. If each σ0 is greater than the corresponding σ, the inner flow channel profile is qualified.

[0014] Secondly, this application provides a telescopic air intake, wherein the inner flow channel profile of the telescopic air intake after extension is designed using the above-described design method.

[0015] Thirdly, embodiments of this application provide an aircraft equipped with the aforementioned telescopic air intake.

[0016] The beneficial effects of the technical solutions provided in this application include at least the following: 1. The design method of the retractable air intake of this application involves the following steps: First, when the aircraft is in powered flight, the engine operates, and the air intake of the retractable air intake extends to provide the engine with the required flow rate, thus providing a stable airflow to the engine. When the aircraft enters a powerless gliding state, the engine stops operating, and the air intake of the retractable air intake retracts and is hidden within the fuselage. After retraction, there are no additional protruding structures on the aircraft surface, improving the aerodynamic performance of the aircraft, specifically improving the aerodynamic performance in the gliding state. The retractable air intake of this application satisfies both the requirement that the air intake does not occupy the overall size of the aircraft, facilitating its application in some special scenarios (such as the aircraft landing on an unofficial runway), and the requirement of a high total pressure recovery coefficient (meeting the total pressure recovery coefficient requirements of the engine). More importantly, based on the known quantities L, S, and R, the L0, R0, and S0 of the telescopic intake are determined. Then, the initial internal flow channel profile is designed and optimized more than once. After each optimization and adjustment of the internal flow channel profile, the multiple total pressure recovery coefficients σ0 after the telescopic intake extends under different Mach number conditions are compared with the multiple total pressure recovery coefficient requirements σ required for the engine operation. This process continues until each σ0 is greater than or equal to the corresponding σ, at which point the telescopic intake is considered qualified. In other words, the energy loss (such as shock waves, separation, friction, etc.) of the airflow during the application of this telescopic intake is strictly guaranteed to be within a controllable range, resulting in a highly efficient and low-loss internal flow channel for the intake.

[0017] 2. The design method of the telescopic air intake of this application can greatly speed up the design efficiency by using R0=R, L0=L×w1, S0=S×w2, w1≤1, and 0.8≤w2≤1.2. This is because similar aircraft have already undergone complex calculations and verifications during the design process, so referencing nearby aircraft can reduce the number of subsequent adjustments to the internal flow channel profile.

[0018] 3. The design method of the telescopic air intake in this application minimizes energy loss due to shock waves, separation, and friction by optimizing the streamlined guide surface, and ultimately achieves a high-efficiency, low-loss air intake internal flow channel design. In the process of adjusting the internal flow channel surface to be close to the streamline, there are often cases of adjusting too much or too little, so multiple adjustments are required.

[0019] 4. The design method of the telescopic air intake of this application is as follows: if each σ0 is greater than or equal to the corresponding σ, the telescopic air intake is qualified; if any σ0 is less than the corresponding σ, the telescopic air intake is unqualified. The method returns to obtain the distribution of the airflow streamline in the inner channel and adjust the inner channel profile. This process can be repeated multiple times until the telescopic air intake is qualified. This method can ensure that the energy loss of the telescopic air intake is small and meets the total pressure recovery coefficient requirement value required for engine operation. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the retractable air intake (extended) of this application; Figure 2 This is a schematic diagram of the retractable air intake (retracted) of this application; Figure 3 This is a partial schematic diagram of the telescopic air intake (extended) of this application; Figure 4 This is a partial schematic diagram of the retractable air intake (retracted) of this application; Figure 5 A flowchart illustrating the design method of the telescopic air intake of this application; Figure 6 The lift-to-drag ratio of the aircraft in this application is shown in the extended (dashed line) and retracted (solid line) states of the telescopic air intake when flying unpowered at different Mach numbers. In the diagram: 1. Telescopic air intake; 11. Embedded structure within the fuselage; 12. Telescopic cover. Detailed Implementation

[0022] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0023] It's worth noting that the total pressure recovery coefficient (σ) is a dimensionless parameter that measures the intake's ability to maintain total pressure during airflow, reflecting the efficiency of the intake design. Total pressure (stagnant pressure) is the sum of fluid kinetic energy and static pressure. A higher total pressure recovery coefficient indicates less total pressure loss in the intake due to factors such as shock waves, friction, and airflow separation. This is crucial for engine performance, as higher total pressure translates to higher combustion efficiency and thrust.

[0024] The retractable air intake design method of this application extends and retracts according to different engine operating states, which not only satisfies the requirement that the air intake does not occupy the overall size of the aircraft, but also satisfies the requirement of high total pressure recovery coefficient (meeting the total pressure recovery coefficient requirement of the engine). The air intake extends and retracts when the engine is running and retracts when the engine stops running. It has a high total pressure recovery coefficient, is practical and effective, and is suitable for engineering applications of aircraft air intake design.

[0025] The telescopic air intake 1 is located in the same position in the aircraft as the pitot air intake, S-curve air intake, or embedded air intake of the same type of aircraft.

[0026] Firstly, such as Figure 1 , Figure 2 and Figure 5 As shown, this application discloses a design method for a telescopic air intake duct. The air intake of the telescopic air intake duct 1 extends when working and retracts when not working. The design method for the telescopic air intake duct includes the following steps: Based on the length L of the section of the fuselage under the existing aircraft's air intake (Pitto-type air intake, S-curve air intake, or embedded air intake, etc.), the cross-sectional area S of the air intake of the existing aircraft's air intake, and the known engine front face size R, determine the design length L0 of the fuselage underport corresponding to the telescopic air intake 1, the design radius R0 of the rear port of the telescopic air intake 1, and the cross-sectional area S0 of the extended rear air intake of the telescopic air intake 1.

[0027] Before designing the retractable air intake 1, the engine to be matched was known, i.e., the radius R of the air intake port was known. The closest comparable aircraft was selected from the aforementioned similar aircraft. After selection, the length L of the section occupied by the air intake in the lower fuselage of this comparable aircraft and the cross-sectional area S of the air intake opening were known. In summary, L, S, and R are all known quantities. Based on the known quantities L, S, and R, L0, R0, and S0 were determined according to the established rules.

[0028] Based on L0, R0, and S0, design the initial internal flow channel profile of the telescopic air intake 1 after it extends, according to the set rules.

[0029] The internal flow channel profile is optimized and adjusted at least once. Based on the total pressure recovery coefficient σ required for the aircraft's engine operation under different Mach numbers, there is one total pressure recovery coefficient σ for each Mach number condition, and multiple total pressure recovery coefficient σ for multiple Mach number conditions. After each optimization and adjustment of the internal flow channel profile, multiple total pressure recovery coefficients σ0 after the telescopic air intake 1 is extended under different Mach numbers are obtained. These multiple total pressure recovery coefficients σ0 after the telescopic air intake 1 is extended under different Mach numbers are compared one by one with the multiple total pressure recovery coefficient σ required for engine operation. This process continues until each total pressure recovery coefficient σ0 is greater than or equal to the corresponding total pressure recovery coefficient σ. In other words, the telescopic air intake 1 is considered qualified when all the total pressure recovery coefficients σ0 corresponding to different Mach numbers are greater than or equal to the corresponding total pressure recovery coefficient σ.

[0030] Specifically, the known engine intake port is connected to, for example... Figure 3 The semicircle in the middle (i.e., the rear port of the telescopic air intake 1).

[0031] Specifically, the total pressure recovery coefficient required for engine operation under different Mach numbers is a known quantity, while the multiple total pressure recovery coefficients σ0 after the telescopic intake duct 1 extends under different Mach numbers are simulated actual measurements obtained through simulated wind tunnel tests.

[0032] The design method of the retractable air intake duct in this application involves the following steps: First, when the aircraft is in powered flight, the engine operates, and the air intake of the retractable air intake duct 1 extends to provide the engine with the required flow rate, thus providing a stable airflow. When the aircraft enters a powerless gliding state, the engine stops operating, and the air intake of the retractable air intake duct 1 retracts and is hidden within the fuselage. After retraction, there are no additional protruding structures on the aircraft surface, improving the aerodynamic performance of the aircraft, specifically enhancing its aerodynamic performance during gliding. The retractable air intake duct of this application satisfies both the requirement that the air intake does not occupy the overall size of the aircraft, facilitating its application in special scenarios (such as landing on unofficial runways) and the requirement of a high total pressure recovery coefficient (meeting the total pressure recovery coefficient requirements of the engine). More importantly, based on the known quantities L, S, and R, the L0, R0, and S0 of the telescopic intake duct 1 are determined. Then, the initial internal flow channel profile is designed and optimized more than once. After each optimization and adjustment of the internal flow channel profile, the multiple total pressure recovery coefficients σ0 of the telescopic intake duct 1 after extension under different Mach number conditions are compared with the multiple total pressure recovery coefficient requirements σ required for engine operation. This process continues until each σ0 is greater than or equal to the corresponding σ, at which point the telescopic intake duct 1 is considered qualified. In other words, the energy loss (such as shock waves, separation, friction, etc.) of the airflow during the application of the telescopic intake duct 1 designed in this way is strictly guaranteed to be within a controllable range, resulting in a highly efficient and low-loss internal flow channel for the intake duct.

[0033] Further, in one embodiment, determining L0, R0, and S0 based on L, S, and R includes: R0=R, L0=L×w1, S0=S×w2; Where w1 and w2 are the set weighting coefficients, w1≤1, 0.8≤w2≤1.2.

[0034] Specifically, w1≤1 indicates that the design length L0 of the retractable air intake 1 corresponding to the lower port of the fuselage is smaller than L. In the actual design process, under the premise of being retractable and considering interference and constraints, L0 is made as close to L as possible. 0.8≤w2≤1.2 indicates that S0 is slightly smaller, unchanged, or slightly larger than S. The design method of the telescopic air intake in this application can greatly accelerate the design efficiency by using R0=R, L0=L×w1, S0=S×w2, w1≤1, and 0.8≤w2≤1.2. This is because similar aircraft have already undergone complex calculations and verifications during the design process, so referencing nearby aircraft can reduce the number of subsequent adjustments to the internal flow channel profile.

[0035] like Figure 3 and Figure 4 As shown, further, in one embodiment, the initial inner flow channel profile of the telescopic intake duct 1 after its extension is designed according to L0, R0, and S0, including: The telescopic air intake duct 1 is divided into an internal fuselage structure 11 and a telescopic cover 12. The surface of the internal fuselage structure 11 above the lower port is set as a quarter circle arc. The surface of the telescopic cover 12 below the lower port is inclined and guided to the rear port of the internal fuselage structure 11 (which is also the front port of the engine air intake), ensuring that the telescopic cover 12 can extend and retract relative to the internal fuselage structure 11, and ensuring the three dimensions L0, R0 and S0, thus forming the initial internal flow channel profile.

[0036] It is worth noting that this application mainly focuses on the design of the inner flow channel profile, while the implementation of the cap telescopic part 12 The telescopic connection structure relative to the internal fuselage structure 11 is not described in detail in this application.

[0037] Specifically, such as Figure 3 As shown, S0 represents the area of ​​the front port of the telescopic part 12 when the telescopic part 12 is fully extended; L0 represents the inner wall spacing of the lower port of the internal structure 11; and R0 represents the radius of the rear port of the internal structure 11. Correspondingly, S is the cross-sectional area of ​​the air intake of the existing aircraft's air intake duct; L is the length of the section of the lower fuselage occupied by the air intake of the existing aircraft; and R is the known radius of the engine's air intake port.

[0038] Furthermore, during the extension and retraction of the cover extension part 12 relative to the fuselage embedded structure 11, it is ensured that the cover extension part 12 does not interfere with the fuselage embedded structure 11, and that the cover extension part 12 fits tightly against the surface of the aircraft without any additional protrusions.

[0039] Furthermore, during the process of optimizing and adjusting the inner flow channel profile, it is always ensured that the expansion joint 12 of the cover extends relative to the embedded structure 11 of the fuselage, that is, during the extension and retraction of the cover extension joint 12 relative to the embedded structure 11 of the fuselage, the cover extension joint 12 and the embedded structure 11 of the fuselage do not interfere with each other.

[0040] Furthermore, in one embodiment, optimizing the inner flow channel profile more than once includes: Each optimization adjustment involves adjusting the inner flow channel profile of the intake duct based on the distribution of the airflow streamlines, so that the inner flow channel profile closely matches the airflow streamlines. Specifically, streamlines are curves formed by the tangents in the instantaneous velocity direction of airflow during its flow, reflecting the trend of airflow motion. Streamlines are the natural flow paths of airflow. The closer the internal flow channel profile is to the streamlines, the smaller the shearing force between the airflow and the wall, resulting in lower flow separation and turbulence losses, thereby improving the total pressure recovery coefficient.

[0041] When the total pressure recovery coefficient is unqualified (i.e., the total pressure recovery coefficient is less than the required value of the total pressure recovery coefficient for engine operation), it indicates that the energy loss (such as shock waves, separation, friction, etc.) during the airflow process is too large; when the total pressure recovery coefficient is qualified (i.e., the total pressure recovery coefficient is greater than or equal to the required value of the total pressure recovery coefficient for engine operation), it indicates that the energy loss (such as shock waves, separation, friction, etc.) during the airflow process is within a controllable range.

[0042] The design method of the telescopic air intake in this application minimizes energy loss due to shock waves, separation, and friction by optimizing the streamlined guide surface, ultimately achieving a high-efficiency, low-loss internal flow channel design. However, in the process of adjusting the internal flow channel profile to be closer to the streamline, there are often cases of adjusting too much or too little, so multiple adjustments are required.

[0043] Furthermore, the distribution of the airflow streamlines in the internal flow channel is obtained through CFD (Computational Fluid Dynamics) simulation or wind tunnel test simulation.

[0044] Furthermore, in one embodiment, each Mach number condition corresponds to a total pressure recovery coefficient σ0 and a total pressure recovery coefficient requirement value σ; The internal flow channel profile is optimized and adjusted more than once, including: The distribution of the airflow streamlines in the inner flow channel is obtained, and the inner flow channel profile of the intake is adjusted to make the inner flow channel profile closer to the airflow streamlines, thus obtaining the adjusted inner flow channel profile. Obtain multiple total pressure recovery coefficients σ0 of the retractable air intake 1 after its extension under different Mach numbers, based on the adjusted internal flow channel profile. Compare each σ0 with the required total pressure recovery coefficient values ​​σ for engine operation. If each σ0 is greater than or equal to the corresponding σ, the retractable air intake 1 is qualified; if any σ0 is less than the corresponding σ, the retractable air intake 1 is unqualified. If the retractable air intake 1 is unqualified, then... Return to obtain the distribution of the airflow streamline in the inner channel, readjust the inner channel profile of the intake to make the inner channel profile closer to the airflow streamline, and re-compare multiple σ0 and multiple σ. This process can be repeated multiple times until the multiple total pressure recovery coefficients σ0 corresponding to different Mach numbers are greater than or equal to the corresponding multiple total pressure recovery coefficient requirements σ. The telescopic intake 1 is then qualified.

[0045] Furthermore, during multiple cycles, it is always ensured that it can extend and retract normally, that is, the extension and retraction of the cover extension part 12 relative to the internal structure 11 of the fuselage does not interfere with each other during the extension and retraction process.

[0046] The design method of the telescopic air intake in this application is as follows: if each σ0 is greater than or equal to the corresponding σ, the telescopic air intake 1 is qualified; if any σ0 is less than the corresponding σ, the telescopic air intake 1 is unqualified. The method then returns to obtain the distribution of the airflow streamline in the inner channel and adjusts the inner channel profile. This process can be repeated multiple times until the telescopic air intake 1 is qualified. This method can ensure that the energy loss of the telescopic air intake 1 is small and meets the total pressure recovery coefficient requirement for engine operation.

[0047] Furthermore, in one embodiment, the telescopic air intake duct 1 is divided into an internal fuselage structure 11 and a telescopic cover 12. The inner wall length of the lower port of the internal fuselage structure 11 is equal to L0, and the inner wall radius of the rear port of the internal fuselage structure 11 is R0. That is, after deducting the wall thickness of the internal fuselage structure 11 and the telescopic cover 12, the dimensions can still guarantee L0 and R0.

[0048] In one example, the total pressure recovery coefficient σ0 of an inner flow channel profile of the telescopic air intake 1 under different Mach number conditions Ma of 0.6, 0.5, 0.4, and 0.25 are 0.927, 0.966, 0.975, and 0.986, respectively, and the corresponding required total pressure recovery coefficient σ is 0.91, 0.94, 0.95, and 0.96, respectively. Each σ0 is greater than the corresponding σ, indicating that the inner flow channel profile is qualified. The Ma-σ-σ0 data for this inner flow channel profile are shown in Table 1.

[0049] Table 1

[0050] Furthermore, such as Figure 6 As shown, the lift-to-drag ratio of the aircraft in the extended and retracted states when the air intake is in unpowered flight (engine not working) is compared. The dashed line represents the extended air intake state, and the solid line represents the retracted air intake state.

[0051] It can be seen that when the engine is not working, the extended engine generates negative lift for the aircraft, resulting in a negative lift-to-drag ratio. The retracted air intake can significantly improve the lift-to-drag ratio of the aircraft. When Ma=0.25~0.6, the maximum increase in lift-to-drag ratio is about 7.48 (the distance between the solid and dashed lines), indicating that the retracted air intake state is more conducive to the aircraft's unpowered gliding and has better stable landing performance.

[0052] Secondly, this application also discloses a telescopic air intake, wherein the inner flow channel profile of the telescopic air intake 1 after extension is designed using the above-mentioned design method.

[0053] Thirdly, an aircraft equipped with the aforementioned air intake.

[0054] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0055] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0056] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A design method for a telescopic air intake, characterized in that, The air inlet of the telescopic air intake (1) extends when working and retracts when not working, and the design method includes the following steps: Based on the length L of the section of the fuselage occupied by the air intake of the same type of aircraft, the cross-sectional area S of the air intake of the air intake, and the known radius R of the front air intake port of the engine, the design length L0 of the lower fuselage port of the telescopic air intake (1), the design radius R0 of the rear port of the telescopic air intake (1), and the cross-sectional area S0 of the rear air intake of the telescopic air intake (1) are determined. Based on L0, R0 and S0, design the initial internal flow channel profile of the telescopic intake (1) after it is extended; The internal flow channel profile is optimized and adjusted more than once. Based on the total pressure recovery coefficient required by the aircraft's own engine under different Mach number conditions, after each optimization and adjustment, the multiple total pressure recovery coefficients σ0 after the telescopic air intake (1) is extended under different Mach number conditions are compared with the multiple σ required for the engine to work, until each σ0 is greater than or equal to the corresponding σ, and the telescopic air intake (1) is qualified.

2. The design method of a telescopic air intake as described in claim 1, characterized in that, Determining L0, R0, and S0 based on L, S, and R includes: R0=R, L0=L×w1, S0=S×w2; Where w1 and w2 are set weighting coefficients, where w1≤1 and 0.8≤w2≤1.

2.

3. The design method of a telescopic air intake as described in claim 1, characterized in that, Based on L0, R0, and S0, the initial internal flow channel profile of the telescopic intake (1) after extension is designed, including: The telescopic air intake (1) is divided into an internal fuselage structure (11) and a telescopic cover (12). The surface of the internal fuselage structure (11) above the lower port is set as a quarter circle arc. The surface of the telescopic cover (12) below the lower port is inclined and guided to the rear port of the internal fuselage structure (11), ensuring that the telescopic cover (12) can extend and retract relative to the internal fuselage structure (11) and ensuring the three dimensions L0, R0 and S0.

4. The design method of a telescopic air intake as described in claim 1, characterized in that, The internal flow channel profile is optimized and adjusted more than once, including: Each optimization adjustment involves adjusting the inner flow channel profile of the intake duct based on the distribution of the airflow streamlines, so that the inner flow channel profile closely matches the airflow streamlines.

5. The design method of a telescopic air intake as described in claim 4, characterized in that, The distribution of the airflow streamlines in the internal flow channel is obtained through CFD simulation or wind tunnel test simulation.

6. The design method of a telescopic air intake as described in claim 5, characterized in that: Each Mach number condition corresponds to a total pressure recovery coefficient σ0 and a total pressure recovery coefficient requirement value σ; The internal flow channel profile is optimized and adjusted more than once, including: The distribution of the airflow streamlines in the inner flow channel is obtained, and the inner flow channel profile of the intake is adjusted to make the inner flow channel profile close to the airflow streamlines, thus obtaining the adjusted inner flow channel profile. Obtain the total pressure recovery coefficients σ0 of the telescopic intake (1) after it extends under different Mach number conditions, and compare them one by one with the total pressure recovery coefficient requirements σ required for the engine operation; if each σ0 is greater than or equal to the corresponding σ, the telescopic intake (1) is qualified; if any σ0 is less than the corresponding σ, the telescopic intake (1) is unqualified, and return to obtain the distribution of the airflow streamline of the inner channel and adjust the inner channel profile until the telescopic intake (1) is qualified.

7. The design method of a telescopic air intake as described in claim 1, characterized in that: The telescopic air intake (1) is divided into an internal fuselage structure (11) and a telescopic cover (12). The inner wall length of the lower port of the internal fuselage structure (11) is equal to L0, and the inner wall radius of the rear port of the internal fuselage structure (11) is R0.

8. The design method of a telescopic air intake as described in claim 1, characterized in that: The inner flow channel profile of the telescopic air intake (1) has total pressure recovery coefficients σ0 of 0.927, 0.966, 0.975 and 0.986 respectively under different Mach number conditions Ma of 0.6, 0.5, 0.4 and 0.25, and the corresponding total pressure recovery coefficient requirements σ are 0.91, 0.94, 0.95 and 0.96 respectively. Each σ0 is greater than the corresponding σ, and the inner flow channel profile is qualified.

9. A telescopic air intake, characterized in that: The telescopic air intake (1) is designed using the design method described in claim 1.

10. An aircraft, characterized in that, The aircraft is equipped with a telescopic air intake as described in claim 9.

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