Wide-speed-range adjustable internal contraction air inlet channel and control method

Abstract

The invention provides a wide-speed-range adjustable inward-contraction air inlet channel and a control method, and relates to the field of aero-engines, the wide-speed-range adjustable inward-contraction air inlet channel comprises an air inlet channel body, a plug cone and a driving assembly, the plug cone is arranged at an inward-contraction type throat part of the air inlet channel, and a motor drives the plug cone to move in the axial direction through rotation, so that the effective area of the throat part is adjusted. One end of the fixing rod is connected with the motor, and the other end of the fixing rod is fixed to the wall face of the air inlet channel through the supporting rod. According to the design of the air inlet channel, under the low Mach number incoming flow condition, the good startability is provided through the large internal contraction throat area; under the high Mach number, the plug cone is moved to adjust the throat area, expected compression of airflow is achieved, the air inlet efficiency is improved, and normal work of the engine is guaranteed. According to the design of the air inlet channel, the contradiction between low Mach number startability and high Mach number compression efficiency is solved, the working Mach number range of the internal contraction air inlet channel is widened, and wide-speed-range operation is supported.

Description

Technical Field

[0001] The invention relates to the technical field of aero-engines, and in particular to a wide-speed-range adjustable internally retractable air inlet and a control method thereof. Background Art

[0002] With the rapid development of aerospace technology in recent years, higher requirements have been put forward for the performance of hypersonic aircraft. The maximum operating Mach number of traditional turbine / turbofan jet engines does not exceed 3, and the specific impulse is the highest under working conditions; the operating range of scramjet engines is between Mach numbers 2 and 5, and the specific impulse is second; under flight conditions where the Mach number is greater than 5, only scramjet engines can maintain working conditions. Rocket engines have a wide range of applications and a wide range of operating Mach numbers, but the specific impulse is the lowest and the cost is high. Therefore, scramjet engines have become the preferred power device for hypersonic aircraft, and are increasingly highly valued and studied in depth by countries around the world. Scramjet engines are mainly composed of hypersonic inlet ducts, isolation sections, combustion chambers and tail nozzles. As the front-end intake component, the hypersonic inlet duct is responsible for decelerating and pressurizing the free flow. Its overall performance and outlet flow field directly affect the performance of the engine. Therefore, people have also conducted in-depth and extensive research on hypersonic inlets.

[0003] According to the structure, supersonic inlets can be divided into three typical types: axisymmetric, binary and side pressure inlets, as well as new three-dimensional inward-contracting inlets. Compared with traditional binary plane compression and side pressure inlets, the three-dimensional inward-contracting inlet adopts the technology of streamline tracking of the reference flow field in design, which largely maintains the compression characteristics of the reference flow field, and the inlet and outlet cross-sectional shapes can also be controlled. Although the characteristics of efficient compression in three-dimensional space make the inward-contracting inlet have extremely high application value, it also faces some problems from the perspective of practical application. On the one hand, the supersonic inward-contracting inlet is generally designed according to high Mach number, so it has better performance when the flow is at high Mach number. However, since the supersonic inward-contracting inlet has a high flow coefficient throughout the entire operating range, the inward-contracting inlet often does not start when the flow is at low Mach number. If a low Mach number design is adopted, the problem of high Mach number compression efficiency cannot be met. Such a contradiction limits the operation of the supersonic inward-contracting inlet in a wide speed range. The two-dimensional inlet can solve the above problems by using variable geometry, but the different compression surfaces of the inward-contracting inlet are connected to each other, and it is not easy to split them into independent modules for variable geometry adjustment. Therefore, how to improve the starting problem of the inward-contracting inlet and the design method that takes into account the high Mach number compression efficiency from the design level is an important basis for expanding the wide-speed range operation of the supersonic inward-turning inlet. Summary of the invention

[0004] In view of this, the present invention proposes a wide-speed-range adjustable inward-retracting inlet and a control method, aiming to resolve the contradiction between the starting of the inward-retracting inlet at low Mach numbers and the efficient compression at high Mach numbers, thereby expanding the wide-speed-range operating range of the supersonic inward-retracting inlet.

[0005] The technical solution of the present invention is achieved in this way:

[0006] In a first aspect, the present invention provides an inwardly retractable air intake duct that is adjustable over a wide speed range, comprising:

[0007] The inlet runner body has an inwardly constricted throat;

[0008] A plug cone, the plug cone being arranged at the throat;

[0009] A drive assembly includes a motor, a fixing rod and a support rod. The motor is located inside the plug cone and drives the plug cone to move axially along the inlet flow body by rotation to change the effective area of ​​the throat. One end of the fixing rod is connected to the motor, and the other end is fixedly connected to the wall of the inlet flow body through the support rod.

[0010] On the basis of the above technical solution, preferably, the driving assembly further comprises a connecting rod, one end of which is fixedly connected to the output shaft of the motor, and the other end of which is located at the axis of the fixed rod and is threadedly connected to the fixed rod.

[0011] On the basis of the above technical solution, preferably, the plug cone includes a cone and a guide sleeve fixedly connected to the cone, the motor is fixedly arranged in the cone, and the guide sleeve is movably sleeved on the outside of the fixed rod and can rotate and axially displace along the fixed rod.

[0012] On the basis of the above technical solution, preferably, the connecting rod is hollow inside to accommodate wires for electrically connecting the motor to the outside.

[0013] On the basis of the above technical solution, preferably, the support rod is provided in plurality, and the plurality of support rods are evenly distributed on the outside of the fixed rod, one end of the support rod is fixedly connected to the outer wall of one end of the fixed rod away from the plug cone, and the other end is fixedly connected to the wall surface of the inlet duct body.

[0014] Based on the above technical solution, preferably, one of the support rods is hollow inside and connected to the axis of the fixing rod, so as to establish an electrical connection between the external electrical connection wire and the motor through the support rod, the fixing rod and the connecting rod.

[0015] On the basis of the above technical solution, preferably, the contraction ratio of the throat is determined by the following method: based on the aircraft operating speed range, structural dimensions and starting performance requirements at the minimum inflow Mach number of the engine, the ratio of the throat area to the inlet area is calculated.

[0016] On the basis of the above technical solution, preferably, the throat shape of the inlet flow channel body is circular or polyhedral.

[0017] In a second aspect, the present invention discloses a control method for a wide speed range adjustable inner contraction air intake duct, comprising the following steps:

[0018] S1. Determine the range of contraction ratio variation and the corresponding relationship between Mach number and contraction ratio according to the flow channel profile and the engine performance requirements under different incoming flow Mach numbers;

[0019] S2. Determine the structural dimensions of the plug cone according to the flow channel profile and the range of contraction ratio;

[0020] S3, determining the distance that the plug cone needs to move forward in the moving direction according to the current Mach number of the incoming flow and the current position of the plug cone, and then determining whether the motor rotates forward or reverse according to the moving direction, and converting the power-on time of the motor according to the distance and the preset rotation speed;

[0021] S4, the motor drives the cone to move to a predetermined position according to a given working time;

[0022] S5. If there is a deviation in the position, recalculate the movement distance and repeat the above steps S3-S4 until the preset accuracy requirement is met;

[0023] S6. Determine whether the performance of the air intake duct in the current state meets the expected performance requirements. If not, go to step S1; otherwise, the operation ends, and the throat contraction ratio adjustment in the current state is completed.

[0024] On the basis of the above technical solution, preferably, step S3 also includes: collecting airflow pressure data of the throat area in real time, dynamically correcting the moving distance of the plug cone according to pressure changes, and adjusting the power-on time of the motor.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) Compared with the throat area of ​​the same type of traditional inward-contracting air inlet under low Mach number flow conditions, the throat area of ​​the inward-contracting air inlet of the present invention is larger, which makes the inward-contracting air inlet have better starting performance under low Mach number flow conditions. Under high Mach number flow conditions, the throat area can be adjusted by moving the plug cone to achieve the expected compression of the airflow, improve the efficiency of the air inlet, and ensure the normal operation of the engine under high Mach number. Such a design eliminates the contradiction between good starting performance at low Mach number and efficient compression at high Mach number, broadens the working Mach number range of the inward-contracting air inlet, and can achieve operation in a wide speed range.

[0027] (2) Compared with other variable geometry methods of the inward-contracting air intake duct, the present invention does not use a complex adjustment mechanism. It achieves the change of the throat area through a simple motor and plug-cone structure, which reduces the mechanical complexity and failure rate and improves the reliability and maintainability of the system. In addition, during the change of the throat area, the wall position of the air intake duct remains unchanged and the overall structure remains the same. This design does not need to consider complex issues such as airflow sealing, simplifies the design complexity, and reduces manufacturing and maintenance costs.

[0028] (3) Due to the threaded connection between the connecting rod and the fixed rod, the rotation of the connecting rod causes axial displacement relative to the fixed rod. This design can accurately control the displacement of the plug cone and adjust the throat area. The threaded connection provides a high-precision linear motion method, avoiding the errors in the traditional mechanical transmission system, ensuring the adjustment accuracy of the plug cone, and thus optimizing the airflow control of the intake duct.

[0029] (4) By setting up fewer support rods, on the one hand, it can ensure that the fixed rod maintains structural stability in the air intake space; on the other hand, it can make the internal space of the air intake more open, reduce the contact area between the support rod and the airflow, help reduce airflow interference, optimize the intake efficiency, and at the same time have a lightweight design.

[0030] (5) By making one of the support rods hollow inside and connected to the axis of the fixed rod, and at the same time setting the connecting rod hollow, the wires of the external electrical connection can smoothly pass through the support rod, the fixed rod, and the connecting rod to achieve electrical connection with the motor, so that the wires are hidden in the drive assembly, which not only saves space but also avoids the interference of electrical circuits on airflow, thereby optimizing the fluid dynamics performance of the intake duct.

[0031] (6) The control method disclosed in the present invention uses closed-loop feedback control and precise plug cone position adjustment to adjust the position and shape of the plug cone in real time, so that the intake duct can adapt to different flow rates and Mach numbers in a wide speed range, ensuring that the engine always operates under the best intake conditions. The advantage of this method is that the intake duct can be dynamically adjusted according to real-time data, providing higher control accuracy and system adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 It is a schematic diagram of the overall structure of the wide speed range adjustable inner retractable air intake disclosed by the present invention;

[0034] Figure 2 It is a schematic diagram of the internal structure of the wide speed range adjustable internally retractable air intake disclosed by the present invention;

[0035] Figure 3 It is a schematic diagram of throat area calculation disclosed in the present invention;

[0036] Figure 4 It is a schematic diagram of the starting position of the plug cone movement disclosed in the present invention;

[0037] Figure 5 It is the farthest movement position of the plug cone disclosed in the present invention;

[0038] Figure 6 Disclosed for the present invention is a flow chart of the movement of the plug cone;

[0039] Figure 7 The present invention discloses a schematic diagram of the control and feedback adjustment principle of the moving position of the plug cone.

[0040] Reference numerals:

[0041] 1. Inlet runner body; 11. Throat; 2. Plug cone; 3. Drive assembly; 31. Motor; 32. Fixing rod; 33. Support rod; 34. Connecting rod; 21. Cone; 22. Guide sleeve. DETAILED DESCRIPTION

[0042] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] like Figure 1 As shown, combined Figure 2 An embodiment of the present invention discloses an inwardly contracting air inlet with a wide speed range and adjustable operation, comprising an air inlet flow channel body 1, a plug cone 2 and a driving assembly 3.

[0044] Among them, the inlet runner body 1 is the main part of the inlet duct, responsible for guiding the air to flow into the engine. The throat 11 is the narrowest part of the inlet duct, used to adjust the flow rate and pressure of the airflow. The design of the inward-contracted throat 11 can increase the area of ​​the throat 11 under low Mach number conditions and improve starting performance.

[0045] The plug cone 2 is arranged at the throat 11. By moving the plug cone 2 in the axial direction of the inlet flow channel body 1, the effective area of ​​the throat 11 of the inward contraction inlet can be changed, thereby changing the contraction ratio of the inward contraction inlet.

[0046] The driving assembly 3 includes a motor 31, a fixing rod 32 and a supporting rod 33. The motor 31 is located inside the plug cone 2 and drives the plug cone 2 to move axially along the inlet flow channel body 1 by rotation to change the effective area of ​​the throat 11. Placing the motor 31 inside the plug cone 2 can directly drive the plug cone 2 to move relative to the fixing rod 32 by the rotation of the motor 31. This built-in design helps save space and eliminates the external driving device and complex transmission system that may be required in the traditional structure. This design not only saves space, but also simplifies the structure of the system and reduces the probability of failure.

[0047] In this embodiment, the axial movement of the plug cone 2 is precisely controlled by the rotation of the motor 31, so the forward and reverse rotation of the motor 31 realizes the forward and backward movement of the plug cone 2, changes the effective area of ​​the supersonic inward-contracting air inlet throat 11, and thus changes the contraction ratio of the inward-contracting air inlet.

[0048] One end of the fixing rod 32 is connected to the motor 31 to ensure that the motor 31 does not shift during operation, thereby ensuring the stable movement of the plug cone 2. The other end of the fixing rod 32 is fixedly connected to the wall surface of the inlet channel body 1 through the support rod 33. This structure can ensure that the motor 31 and the plug cone 2 are supported firmly, and ensure that the plug cone 2 can maintain a stable motion trajectory during operation without being disturbed by external factors.

[0049] Compared with the throat 11 area of ​​the same type of traditional inward-contracting air inlet under low Mach number flow conditions, the throat 11 area of ​​the inward-contracting air inlet of the present invention is larger, which makes the inward-contracting air inlet have better starting performance under low Mach number flow conditions. Under high Mach number flow conditions, the area of ​​the throat 11 can be adjusted by moving the plug cone 2 to achieve the expected compression of the airflow, improve the efficiency of the air inlet, and ensure the normal operation of the engine under high Mach numbers. Such a design eliminates the contradiction between good starting performance at low Mach numbers and efficient compression at high Mach numbers, broadens the working Mach number range of the inward-contracting air inlet, and can achieve operation in a wide speed range.

[0050] Compared with other variable geometry methods of the inner contraction air intake duct, the present invention does not use a complex adjustment mechanism, and realizes the change of the throat 11 area through a simple motor 31 and a plug cone 2 structure, which reduces the mechanical complexity and failure rate, and improves the reliability and maintainability of the system. In addition, during the change of the throat 11 area, the wall position of the air intake duct remains unchanged, and the overall structure remains the same. This design does not need to consider complex issues such as airflow sealing, simplifies the design complexity, and reduces manufacturing and maintenance costs.

[0051] As some embodiments, the driving assembly 3 further includes a connecting rod 34, one end of which is fixedly connected to the output shaft of the motor 31, and the other end of which is located at the axis of the fixed rod 32 and is threadedly connected to the fixed rod 32. In this embodiment, the axis of the fixed rod 32 has an internal thread, and the connecting rod 34 is a screw structure, and the connecting rod 34 can rotate and translate with the fixed rod 32.

[0052] By adopting the above technical solution, the motor 31 drives the connecting rod 34 to rotate, and the relative rotation between the connecting rod 34 and the fixed rod 32 causes displacement. It can be understood that when the connecting rod 34 rotates, it shifts relative to the fixed rod 32, that is, the connecting rod 34 translates axially relative to the fixed rod 32 during the rotation process.

[0053] Since the connecting rod 34 is fixedly connected to the motor 31 in the plug cone 2, and the motor 31 is fixedly connected to the plug cone 2, the motor 31 and the plug cone 2 will rotate or move with the rotation of the connecting rod 34. This displacement causes the plug cone 2 to move relative to the fixed rod 32, thereby adjusting the area of ​​the throat 11.

[0054] Due to the threaded connection between the connecting rod 34 and the fixed rod 32, the rotation of the connecting rod 34 brings about an axial displacement relative to the fixed rod 32. This design can accurately control the displacement of the plug cone 2 and adjust the area of ​​the throat 11. The threaded connection provides a high-precision linear motion method, avoids errors in traditional mechanical transmission systems, ensures the adjustment accuracy of the plug cone 2, and thus optimizes the airflow control of the intake duct.

[0055] Compared with the traditional complex adjustment mechanism, the present invention adopts a structure in which the screw rod is connected to the output shaft of the motor 31. The rotation of the motor 31 drives the connecting rod 34 to rotate, and the connecting rod 34 is displaced by the action of the thread. This design simplifies the entire adjustment mechanism, reduces unnecessary mechanical transmission components, and makes the system more compact and reliable.

[0056] As some preferred embodiments, the plug cone 2 includes a cone 21 and a guide sleeve 22 fixedly connected to the cone 21, the motor 31 is fixedly arranged in the cone 21, and the guide sleeve 22 is movably sleeved on the outside of the fixed rod 32 and can rotate and axially move along the fixed rod 32.

[0057] In this embodiment, the arrangement of the cone 21 can make the change of the area of ​​the throat 11 smoother and more gradual, avoiding sudden changes that cause airflow instability. The shape of the cone 21 helps to accurately adjust the effective flow area of ​​the air inlet, thereby accurately adjusting the airflow rate, especially when flying at high speed, to maintain good airflow control characteristics.

[0058] The function of the guide sleeve 22 is to ensure that the cone 21 maintains stable guidance during the adjustment process and enables it to rotate and axially displace along the fixed rod 32, ensuring that the plug cone 2 maintains a smooth trajectory during movement and avoiding the plug cone 2 from deviating from the predetermined trajectory, thereby improving the stability and accuracy of the adjustment process.

[0059] In some embodiments, the connecting rod 34 is hollow inside to accommodate the wires for connecting the motor 31 to the external electrical system. The hollow design is generally used to reduce the weight of the component and provide a convenient passage for the electrical circuit. In this way, the connection between the motor 31 and the external electrical system can be more concise and compact, and the wires placed inside the connecting rod 34 can avoid damage due to high temperature.

[0060] In some embodiments, a plurality of support rods 33 are provided, and the plurality of support rods 33 are evenly distributed on the outside of the fixed rod 32. One end of the support rod 33 is fixedly connected to the outer wall of the end of the fixed rod 32 away from the plug cone 2, and the other end is fixedly connected to the wall surface of the inlet channel flow body 1. This structural setting helps to provide a stable supporting force, so that the fixed rod 32 remains stable in space. Preferably, the number of support rods 33 is three, and the design of three support rods 33 can form a stable triangular support structure. This structure has high mechanical stability and torsion resistance, which can ensure that the fixed rod 32 remains balanced and symmetrical in space, and avoids tilting or swinging caused by uneven force on one side. In addition, the design of fewer support rods 33 can make the internal space of the inlet more open, reduce the contact area between the support rod 33 and the airflow, help reduce airflow interference, optimize the intake efficiency, and have a lightweight design.

[0061] In some embodiments, one of the support rods 33 is hollow inside and connected to the axis of the fixed rod 32, and is used to connect the wire of the external electrical connection to the motor 31 through the support rod 33, the fixed rod 32, and the connecting rod 34. With this structural setting, the wire of the external electrical connection can smoothly pass through the support rod 33, the fixed rod 32, and the connecting rod 34 to achieve electrical connection with the motor 31, so that the wire is hidden in the drive assembly 3, which not only saves space, but also avoids the interference of the electrical circuit on the airflow, and optimizes the fluid dynamics performance of the air intake duct.

[0062] As some embodiments, the wire in the fixed rod 32 is configured as a spiral cable, the length of the wire in the fixed rod 32 is greater than 1.5 times the maximum displacement distance of the connecting rod 34, and is pre-wound into a spring shape along the axis direction of the fixed rod 32. With this configuration, the spiral cable is accommodated inside the connecting rod 34, and when the connecting rod 34 is moving, it drives the spiral cable to stretch. Due to the elastic characteristics of the spiral cable, it can be repeatedly stretched and retracted without losing elasticity and bearing capacity. At the same time, the connecting rod 34 moves horizontally by rotating in the fixed rod 32, so the spiral cable will also rotate with it. Since the spiral cable is in a spring shape, it has a certain torsional resistance and can adapt to rotation and movement in a dynamic environment.

[0063] The length of the spiral cable in the fixing rod 32 is set to be greater than 1.5 times the maximum displacement distance of the connecting rod 34, in order to ensure that the cable will not be pulled too tight or subjected to excessive tension when the plug cone 2 moves. With this design, the spiral cable has enough margin to adapt to the displacement of the system, avoiding the risk of the cable being broken or damaged.

[0064] In this embodiment, the contraction ratio of the throat 11 is determined by calculating the ratio of the throat 11 area to the inlet area based on the aircraft operating speed range, structural dimensions and starting performance requirements at the minimum engine inflow Mach number.

[0065] Specifically, the specific position of the plug cone 2 in the throat 11 changes with the change of the incoming flow Mach number. The relationship between the incoming flow Mach number and the contraction ratio is shown in formula (1). Ma is the actual incoming flow Mach number, Ma1 is the minimum incoming flow Mach number, and Ma2 is the maximum incoming flow Mach number.

[0066] CR=f(Ma) (Ma1≤Ma≤Ma2) (1)

[0067] Under the condition of known incoming flow Mach number, the throat contraction ratio can be determined. Then the throat area can be determined by the definition of contraction ratio and inlet area. Then the moving distance of the plug cone can be determined by the relationship between the throat area and the position of the plug cone. The calculation process of the throat area is as follows. Considering that the throat 11 and the plug cone 2 are both circular, the effective area of ​​the throat 11 should be the side area S of the conical truncated cone.

[0068] like Figure 3As shown. The calculation process is explained below. Draw a line parallel to line AB and arc CD intersecting at point E. Draw EF through point E perpendicular to AB at point F. Then the lateral area of ​​the cone-shaped cone formed by rotating line EF around the x-axis is the effective area S of the throat, that is, the difference between the lateral areas of the large cone IEG and the small cone IFH. The calculation expression is shown in formula (2). Among them, EG is the lower base diameter of cone IEG; EI is the generatrix of cone IEG; FH is the lower base diameter of cone IFH; FI is the generatrix of cone IFH.

[0069] S=0.5π·EG·EI-0.5π·FH·FI (2)

[0070] The initial movement position and the farthest movement position of the plug cone 2 are as follows Figure 4 and Figure 5 As shown in Figure 2, the motion distance Δx under different incoming flow Mach numbers is defined as the initial coordinate in the x direction minus the actual position coordinate. The motion position control function is shown in formula (3).

[0071] Δx=g(Ma) (Ma1≤Ma≤Ma2) (3)

[0072] The motion position is controlled according to the control function in the above formula (3). The control process is as follows: Figure 6 As shown, proportional-integral-derivative control (PID) is used for closed-loop control. The PID control parameters are adjusted and determined by considering the errors caused by the entire mechanism motion transmission and component installation. At the same time, feedback regulation is also performed on the control process. The feedback regulation principle is as follows Figure 7 In addition, the motor speed is set to be uniform to ensure that the movement speed of the plug cone is also uniform, to avoid damage to the movement mechanism due to excessive inertia, and to avoid excessive disturbance to the airflow.

[0073] In summary, the present invention achieves a change in the throat area by moving the plug cone forward and backward, thereby controlling the contraction ratio of the intake duct, meeting the requirements of compression efficiency, and achieving stable operation of the engine in a wide speed range.

[0074] As some other embodiments, the throat shape of the inlet flow channel body is circular or polyhedral. Specifically, the circular throat can provide a relatively stable fluid flow, and the circular geometric shape can effectively reduce turbulence and pressure loss in the flow, which is conducive to uniform distribution of the fluid.

[0075] Polyhedral (rectangular, hexagonal, etc.) throat designs can provide more efficient flow control than circular throats in some cases, especially when there are specific requirements for flow and pressure loss. For example, rectangular throat designs can be more easily connected to other structures, reducing installation space and complexity.

[0076] The present invention also discloses a control method for a wide speed range adjustable inner contraction air intake duct, comprising the following steps:

[0077] S1. Determine the range of contraction ratio variation and the corresponding relationship between Mach number and contraction ratio based on the flow channel profile and engine performance requirements under different incoming flow Mach numbers.

[0078] This step first analyzes the geometry (profile) of the inlet duct flow channel and determines the appropriate range of contraction ratios based on different incoming flow Mach numbers (i.e., the ratio of the incoming flow gas velocity to the speed of sound). The contraction ratio refers to the ratio of the minimum cross-sectional area to the maximum cross-sectional area of ​​the inlet throat 11, which directly affects the velocity, pressure and temperature of the airflow.

[0079] At different Mach numbers, the relationship between the contraction ratio and fluid dynamics performance is very important. Usually, when the flow is at high speed (high Mach number), the contraction ratio of the inlet is appropriately reduced to avoid excessive pressure drop or flow instability; when the flow is at low speed (low Mach number), the contraction ratio can be appropriately increased to improve the airflow efficiency.

[0080] S2. Determine the structural dimensions of the plug cone 2 according to the flow channel profile and the range of contraction ratio variation.

[0081] The plug cone 2 is a key component in the intake duct for adjusting the contraction ratio. According to the contraction ratio variation range obtained in step S1, the structural dimensions of the plug cone 2, i.e., the length, angle and shape of the cone 21, are calculated and determined. The dimensions of the cone 21 directly affect the minimum cross-sectional area and airflow velocity of the intake duct, and thus affect the performance of the engine.

[0082] S3. Determine the distance that the plug cone 2 needs to move forward according to the current incoming flow Mach number and the current position of the plug cone 2, and then determine whether the motor 31 rotates forward or reverse according to the moving direction, and calculate the power-on time of the motor 31 according to the distance and the preset rotation speed.

[0083] The current incoming flow Mach number determines to what extent the contraction ratio of the inlet throat 11 should be adjusted according to the incoming flow Mach number measured or calculated in real time. The distance and direction that the plug cone 2 needs to move are calculated according to the current position of the plug cone 2 and the required contraction ratio. According to the required forward or backward distance, it is determined whether the motor 31 should rotate forward or reverse. According to the calculated distance and the preset rotation speed, the power-on time of the motor 31 is further calculated, that is, how long the motor 31 needs to work to move the plug cone 2 to the required position.

[0084] S4, the motor 31 drives the plug cone 2 to move to a predetermined position according to a given working time.

[0085] In this step, the motor 31 starts to operate according to the working time calculated in the previous stage, driving the plug cone 2 to move along the predetermined path. When the motor 31 starts to work, the plug cone 2 will gradually adjust the contraction ratio of the air inlet until the predetermined accuracy requirement is reached.

[0086] S5. If there is a position deviation, recalculate the movement distance and repeat the above steps S3-S4 until the preset accuracy requirement is met.

[0087] In the actual movement process, the stopper cone 2 may fail to reach the target position accurately due to various factors (such as friction, mechanical error, etc.). If the measured position deviation exceeds the preset error range, it is necessary to recalculate the adjustment distance and make corrections.

[0088] S6. Determine whether the performance of the air intake duct in the current state meets the expected performance requirements. If not, go to step S1; otherwise, the operation ends, and the contraction ratio adjustment of the throat 11 in the current state is completed.

[0089] After the plug cone 2 reaches the predetermined position, it is necessary to check whether the performance of the current intake duct meets the expected engine performance requirements. This process can be judged by monitoring systems such as flow sensors, pressure sensors and temperature sensors. If the performance does not meet expectations, it means that the current position of the plug cone 2 needs further adjustment. At this time, it will return to step S1, re-evaluate the adjustment range of the contraction ratio, and readjust it based on the new calculation results. If the performance of the intake duct meets the expected requirements, the adjustment process ends. At this time, the contraction ratio adjustment of the plug cone 2 is completed, and the intake duct system has entered a stable working state.

[0090] The above control method uses closed-loop feedback control and precise adjustment of the position of the plug cone 2, and by real-time adjustment of the position and shape of the plug cone 2, the intake duct can adapt to different flow rates and Mach numbers in a wide speed range, ensuring that the engine always operates under the best intake conditions. The advantage of this method is that the intake duct can be dynamically adjusted according to real-time data, providing higher control accuracy and system adaptability.

[0091] As some implementation methods, step S3 also includes: collecting airflow pressure data of the throat 11 area in real time, dynamically correcting the moving distance of the plug cone 2 according to the pressure change, and adjusting the power-on time of the motor 31.

[0092] By installing a pressure sensor in the throat 11 area, the pressure changes of the airflow are monitored in real time. The pressure data reflects the state changes of the airflow, especially during the adjustment of the intake duct contraction ratio, the pressure fluctuation will directly affect the intake flow rate and flow rate. The throat 11 is the narrowest part of the intake duct, and the airflow will experience a significant pressure drop here. By monitoring the airflow pressure of the throat 11 with a pressure sensor, the current fluid state of the intake duct (such as whether it is close to critical flow or flow instability) can be more intuitively understood.

[0093] Through real-time pressure monitoring and dynamic adjustment, the system can more accurately control the movement of the plug cone 2 and the contraction ratio of the inlet duct, avoiding unstable performance caused by airflow fluctuations. This method can adapt to different operating environments in real time. Whether it is high-speed cruising or low-speed starting, the system can dynamically adjust according to the changes in airflow pressure, thereby maintaining efficient operation of the system.

[0094] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A wide speed range adjustable inner retractable air intake, characterized in that: include: The air inlet flow channel body (1) has an inwardly contracted throat (11); A plug cone (2), wherein the plug cone (2) is arranged at the throat (11); A drive assembly (3) comprises a motor (31), a fixing rod (32) and a support rod (33); the motor (31) is located inside the plug cone (2) and drives the plug cone (2) to move axially along the inlet flow channel body (1) by rotation so as to change the effective area of ​​the throat (11); one end of the fixing rod (32) is connected to the motor (31), and the other end is fixedly connected to the wall surface of the inlet flow channel body (1) through the support rod (33).

2. The wide speed range adjustable inner retractable air intake duct according to claim 1, characterized in that: The driving assembly (3) further comprises a connecting rod (34), one end of which is fixedly connected to the output shaft of the motor (31), and the other end of which is located at the axis of the fixing rod (32) and is threadedly connected to the fixing rod (32).

3. The wide speed range adjustable inner retractable air intake duct according to claim 2, characterized in that: The plug cone (2) comprises a cone (21) and a guide sleeve (22) fixedly connected to the cone (21); the motor (31) is fixedly arranged in the cone (21); the guide sleeve (22) is movably sleeved on the outside of a fixed rod (32) and can rotate and axially move along the fixed rod (32).

4. The wide speed range adjustable inner retractable air intake duct according to claim 2, characterized in that: The connecting rod (34) is hollow inside and is used to accommodate a wire for electrically connecting the motor (31) to the outside.

5. The wide speed range adjustable inner retractable air intake duct according to claim 4, characterized in that: A plurality of support rods (33) are provided, and the plurality of support rods (33) are evenly distributed outside the fixing rod (32), one end of the support rod (33) is fixedly connected to the outer wall of one end of the fixing rod (32) away from the plug cone (2), and the other end is fixedly connected to the wall surface of the inlet channel body (1).

6. The wide speed range adjustable inner retractable air intake duct according to claim 5, characterized in that: One of the support rods (33) is hollow inside and is connected to the axis of the fixing rod (32), and is used to establish an electrical connection between an external electrical connection wire and the motor (31) through the support rod (33), the fixing rod (32), and the connecting rod (34).

7. The wide speed range adjustable inner retractable air intake duct according to claim 1, characterized in that: The contraction ratio of the throat (11) is determined by calculating the ratio of the throat (11) area to the inlet area based on the aircraft operating speed range, structural dimensions and starting performance requirements at the minimum engine inflow Mach number.

8. The wide speed range adjustable inner retractable air intake duct according to claim 1, characterized in that: The throat (11) of the air inlet flow channel body (1) is circular or polyhedral in shape.

9. A control method for a wide speed range adjustable inner retractable inlet duct according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Determine the range of contraction ratio variation and the corresponding relationship between Mach number and contraction ratio according to the flow channel profile and the engine performance requirements under different incoming flow Mach numbers; S2. Determine the structural dimensions of the plug cone (2) according to the flow channel profile and the range of contraction ratio variation; S3, determining the distance that the plug cone (2) needs to move forward in the moving direction according to the current Mach number of the incoming flow and the current position of the plug cone (2), and then determining whether the motor (31) rotates forward or reversely according to the moving direction, and converting the power-on time of the motor (31) according to the distance and the preset rotation speed; S4, the motor (31) drives the plug cone (2) to move to a predetermined position according to a given working time; S5. If there is a deviation in the position, recalculate the movement distance and repeat the above steps S3-S4 until the preset accuracy requirement is met; S6, judging whether the performance of the air intake duct in the current state meets the expected performance requirements, if not, going to step S1; otherwise, the operation ends, and the contraction ratio adjustment of the throat (11) in the current state is completed.

10. The control method of the wide speed range adjustable inner contraction intake duct according to claim 9, characterized in that: Step S3 also includes: collecting airflow pressure data in the throat (11) area in real time, dynamically correcting the moving distance of the plug cone (2) according to pressure changes, and adjusting the power-on time of the motor (31).

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