Method and device for determining takeoff characteristic speed of transport plane

Abstract

The invention belongs to the technical field of takeoff field domain performance design, and particularly relates to a method and a device for determining takeoff characteristic speed of a transport plane, which are applied to a lower surface blowing flap power lift-increasing transport plane. The method comprises the following steps: S1, determining a take-off ground clearance speed and a use angle of attack in a non-power lift augmentation state; s2, selecting a plurality of ground clearance speeds near the take-off ground clearance speed in the non-power lift augmentation state, determining corresponding residual lift force, and performing interpolation calculation on the take-off ground clearance speed VL0 when the residual lift force is 0; s3, the take-off ground clearance speed VL0 serves as the take-off ground clearance speed circularly input in the lift augmentation state, and the lift augmentation state ground clearance lift coefficient is calculated; and S4, calculating the take-off ground clearance speed output circularly according to the lift-augmentation state ground clearance lift coefficient, returning to the step S3 until the take-off ground clearance speed converges, and calculating the corresponding take-off characteristic speed. The method can quickly and accurately calculate the take-off characteristic speed of the lower surface blowing flap power high-lift transport plane.

Description

Technical Field

[0001] The present application belongs to the technical field of take-off field performance design, and in particular relates to a method and device for determining the take-off characteristic speed of a transport aircraft. Background Art

[0002] The stall speed, nose wheel lift speed, lift-off speed and safety altitude speed of the take-off configuration are the key factors affecting the take-off performance of transport aircraft. The maximum lift coefficient of the take-off configuration of conventional transport aircraft is fixed, but the maximum lift coefficient of the blown flap powered lift transport aircraft varies with thrust and speed, and the take-off thrust is closely related to speed, engine jet efficiency, and jet deflection angle. Therefore, the calculation of the take-off characteristic speed of the blown flap powered lift aircraft is much more complicated than that of conventional aircraft, and conventional algorithms cannot be applied to the calculation of the take-off characteristic speed of the blown flap powered lift transport aircraft. Summary of the invention

[0003] In order to solve the above problems, the present application provides a method and device for determining the characteristic takeoff speed of a transport aircraft, providing technical support for the takeoff field performance calculation of a lower surface blown flap powered lift transport aircraft.

[0004] In a first aspect, the present application provides a method for determining a takeoff characteristic speed of a transport aircraft, which is applied to a power-assisted lift transport aircraft with lower surface blown flaps. The method comprises:

[0005] Step S1, determining the take-off speed and the angle of attack in a non-powered lift state;

[0006] Step S2: Select multiple take-off speeds near the take-off speed in the non-powered lift state, determine the corresponding residual lift, and interpolate and calculate the take-off speed V when the residual lift is 0. L0 ;

[0007] Step S3: Take-off speed V L0 The take-off lift-off speed is used as the cyclic input of the enhanced lift state to calculate the lift coefficient of the enhanced lift state;

[0008] Step S4, calculating the takeoff lift speed output by the loop according to the lift coefficient of the increased lift state, returning to step S3, until the difference between the calculated takeoff lift speed input by the loop and the takeoff lift speed output by the loop is less than the set value, calculating the increased lift state stall speed, takeoff nose wheel lifting speed and safe altitude speed corresponding to the takeoff lift speed output by the loop at this time.

[0009] Preferably, in step S1, the take-off speed V in the non-powered lift state is determined by the following formula: lof :

[0010]

[0011] Among them, CLmax is the maximum lift coefficient of the takeoff configuration in the non-powered lift state, W to is the takeoff weight, ρ is the atmospheric density at the takeoff airport, S ref is the reference wing area of ​​the aircraft.

[0012] Preferably, in step S1, the use angle of attack in the non-powered lift state is determined by the following formula:

[0013]

[0014] α lof =interp1(CLsz,alphasz,C Llof );

[0015] Among them, interp1 is an interpolation function, which is used to interpolate the lift coefficient C in the corresponding relationship table constructed between the angle of attack array alphasz and the lift coefficient array CLsz of the takeoff configuration in the non-powered lift state. Llof The corresponding angle of attack α lof .

[0016] Preferably, in step S2, at least four take-off speeds are selected in a step size of 5-10 m / s near the take-off speed in the non-powered lift state.

[0017] Preferably, in step S2, the remaining lift ΔZ is determined by the following formula:

[0018] ΔZ=L+Z p -W to g;

[0019] Where L = qS ref C Llof-on ; Z p =P xz η j sin(α lof +θ j );P xz =n e P emax (1-K s )K v K h ;n e is the number of engines, L is the lift force off the ground in the lift-up state, Z p is the component of thrust in the lift direction, P emax is the maximum thrust of the engine, K s is the system power extraction factor, K v is the speed correction factor for takeoff thrust, K h is the height correction factor, P xzis the takeoff thrust corrected for power and speed, η j is the engine jet efficiency factor, θ j is the downward deflection angle of the jet disturbed by the flap relative to the fuselage axis, and α is the calculated or selected operating angle of attack.

[0020] Preferably, in step S4, the take-off speed V output by the cycle is calculated by the following formula: lof-on :

[0021]

[0022] Among them, C Lmax-on is the lift coefficient off the ground in the increased lift state, V s-on is the stall speed in the lifting state, V R-on V is the nose wheel lift speed during takeoff in the state of increased lift, 2-on It is the safe altitude speed in the ascending state.

[0023] A second aspect of the present application provides a transport aircraft takeoff characteristic speed determination device, which is applied to a lower surface blown flap powered lift transport aircraft, and the device comprises:

[0024] A non-powered lift state parameter determination module, used to determine the take-off speed and the angle of attack used in the non-powered lift state;

[0025] The module for determining the initial value of the lift state is used to select multiple take-off speeds near the take-off speed in the non-powered lift state, determine the corresponding residual lift, and interpolate the take-off speed V when the residual lift is 0. L0 ;

[0026] The lift coefficient calculation module is used to calculate the takeoff speed V L0 The take-off lift-off speed is used as the cyclic input of the enhanced lift state to calculate the lift coefficient of the enhanced lift state;

[0027] The loop control module is used to calculate the takeoff lift speed of the loop output according to the lift coefficient of the lift-off state, call the lift coefficient calculation module until the difference between the calculated takeoff lift speed of the loop input and the takeoff lift speed of the loop output is less than the set value, and calculate the stall speed of the lift-off state, the takeoff front wheel rotation speed and the safe altitude speed corresponding to the takeoff lift speed output by the loop at this time.

[0028] Preferably, in the non-powered lift state parameter determination module, the take-off speed V in the non-powered lift state is determined by the following formula: lof :

[0029]

[0030] Among them, C Lmaxis the maximum lift coefficient of the takeoff configuration in the non-powered lift state, W to is the takeoff weight, ρ is the atmospheric density at the takeoff airport, S ref is the reference wing area of ​​the aircraft.

[0031] Preferably, in the non-powered lift state parameter determination module, the use angle of attack of the non-powered lift state is determined by the following formula:

[0032]

[0033] α lof =interp1(CLsz,alphasz,C Llof );

[0034] Among them, interp1 is an interpolation function, which is used to interpolate the lift coefficient C in the corresponding relationship table constructed between the angle of attack array alphasz and the lift coefficient array CLsz of the takeoff configuration in the non-powered lift state. Llof The corresponding angle of attack α lof .

[0035] Preferably, in the lift state initial value determination module, at least four lift-off speeds are selected in a step size of 5-10 m / s near the take-off lift speed in the non-powered lift state.

[0036] Preferably, in the lift-increasing state initial value determination module, the residual lift ΔZ is determined by the following formula:

[0037] ΔZ=L+Z p -W to g;

[0038] Where L = qS ref C Llof-on ; Z p =P xz η j sin(α lof +θ j );P xz =n e P emax (1-K s )K v K h ;n e is the number of engines, L is the lift force off the ground in the lift-up state, Z p is the component of thrust in the lift direction, P emax is the maximum thrust of the engine, K s is the system power extraction factor, K v is the speed correction factor for takeoff thrust, K h is the height correction factor, Pxz is the takeoff thrust corrected for power and speed, η j is the engine jet efficiency factor, θ j is the downward deflection angle of the jet disturbed by the flap relative to the fuselage axis, and α is the calculated or selected operating angle of attack.

[0039] Preferably, in the cycle control module, the take-off speed V output by the cycle is calculated by the following formula: lof-on :

[0040]

[0041] Among them, C Lmax-on is the lift coefficient off the ground in the increased lift state, V s-on is the stall speed in the lifting state, V R-on V is the nose wheel lift speed during takeoff in the state of increased lift, 2-on It is the safe altitude speed in the ascending state.

[0042] A third aspect of the present application provides a computer device, comprising a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method for determining the characteristic takeoff speed of a transport aircraft as described above.

[0043] A fourth aspect of the present application provides a readable storage medium, which stores a computer program. When the computer program is executed by a processor, it is used to implement the method for determining the characteristic takeoff speed of a transport aircraft as described above.

[0044] The application can quickly and accurately calculate the characteristic takeoff speed of a powered lift-enhancing transport aircraft with lower surface blown flaps. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a flow chart of a preferred embodiment of the method for determining the characteristic takeoff speed of a transport aircraft of the present application.

[0046] Figure 2 It is a schematic diagram of the structure of a computer device suitable for implementing the embodiments of the present application. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical scheme and advantages of the implementation of this application clearer, the technical scheme in the implementation of this application will be described in more detail in combination with the drawings in the implementation of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described implementation is a part of the implementation of this application, not all of the implementations. The implementation described below with reference to the drawings is exemplary and is intended to be used to explain this application, and cannot be understood as a limitation on this application. Based on the implementation in this application, all other implementations obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The implementation of this application is described in detail below in combination with the drawings.

[0048] In a first aspect, the present application provides a method for determining a characteristic takeoff speed of a transport aircraft, which is applied to a power-assisted lift transport aircraft with blown flaps on the lower surface, such as Figure 1 As shown, the method mainly includes:

[0049] Step S1, determining the take-off speed and the angle of attack in a non-powered lift state;

[0050] Step S2: Select multiple take-off speeds near the take-off speed in the non-powered lift state, determine the corresponding residual lift, and interpolate and calculate the take-off speed V when the residual lift is 0. L0 ;

[0051] Step S3: Take-off speed V L0 The take-off lift-off speed is used as the cyclic input of the enhanced lift state to calculate the lift coefficient of the enhanced lift state;

[0052] Step S4, calculating the takeoff lift speed output by the loop according to the lift coefficient of the increased lift state, returning to step S3, until the difference between the calculated takeoff lift speed input by the loop and the takeoff lift speed output by the loop is less than the set value, calculating the increased lift state stall speed, takeoff nose wheel lifting speed and safe altitude speed corresponding to the takeoff lift speed output by the loop at this time.

[0053] The present application first determines the take-off speed V when the residual lift in the non-powered lift state is 0 through steps S1 and S2. L0 , which is used as the initial input for the cyclic calculation of the lift-off speed in step S3 and step S4.

[0054] In some optional embodiments, in step S1, the take-off speed V in the non-powered lift state is determined by the following formula: lof :

[0055]

[0056] Among them, CLmax is the maximum lift coefficient of the takeoff configuration in the non-powered lift state, W to is the takeoff weight, ρ is the atmospheric density at the takeoff airport, S ref is the reference wing area of ​​the aircraft.

[0057] In some optional implementations, in step S1, the angle of attack used in the non-powered lift state is determined by the following formula:

[0058]

[0059] α lof =interp1(CLsz,alphasz,C Llof );

[0060] Among them, interp1 is an interpolation function, which is used to interpolate the lift coefficient C in the corresponding relationship table constructed between the angle of attack array alphasz and the lift coefficient array CLsz of the takeoff configuration in the non-powered lift state. Llof The corresponding angle of attack α lof .

[0061] In some optional embodiments, in step S2, at least four take-off speeds are selected in a step size of 5-10 m / s near the take-off speed in the non-powered lift state. For example, the take-off speed V in the non-powered lift state calculated in step S1 is lof If the ground speed is 85m / s, then four lift-off speeds of 60m / s, 70m / s, 80m / s and 90m / s can be selected.

[0062] In some optional implementations, in step S2, the remaining lift ΔZ is determined by the following formula:

[0063] ΔZ=L+Z p -W to g;

[0064] Where L = qS ref C Llof-on ; Z p =P xz η j sin(α lof +θ j );P xz =n e P emax (1-K s )K v K h ;n e is the number of engines, L is the lift force off the ground in the lift-up state, Z p is the component of thrust in the lift direction, P emax is the maximum thrust of the engine, Ks is the system power extraction factor, K v is the speed correction factor for takeoff thrust, K h is the height correction factor, P xz is the takeoff thrust corrected for power and speed, η j is the engine jet efficiency factor, θ j is the downward deflection angle of the jet disturbed by the flap relative to the fuselage axis, and α is the calculated or selected operating angle of attack.

[0065] For example, the reference wing area of ​​an aircraft is 353m 2 , wingspan 50.6m, aspect ratio 7.25, wing 1 / 4 chord sweep angle 21°, tip-to-root ratio 0.24. Four high-bypass turbofan engines are hung under the aircraft wing, each with a thrust of 185.5KN. The angle of the engine thrust axis relative to the local wing chord is -5°. The span-wise installation position of the inner engine is 29.6% of the half span, where the wing section installation angle is 3°, and the span-wise installation position of the outer engine is 55% of the half span, where the wing section installation angle is 2.5°, and the aircraft tail strike angle is 11.5°.

[0066] The maximum take-off weight of the aircraft is 265t, the engine take-off thrust is 185.5KN, and the take-off thrust loss factor is 0.07. Take-off configuration: the leading edge slat deflection angle is 15°, the trailing edge flap deflection angle is 25°, and the downward inclination angle of the upper surface of the flap trailing edge is 8°. The depth of the flap part immersed in the engine jet is 2.4m, and the diameter of the jet at the trailing edge of the flap is 5.21m. The engine jet efficiency factor is 0.907, and the jet deflection angle is 12.28°. Speed ​​correction model for take-off thrust: K v =1-0.167V / 80, height correction factor K h Take 1, the system power extraction factor K for takeoff s Take 0.036.

[0067] In step S1, the maximum lift coefficient C of the takeoff configuration in the non-powered lift state is given Lmax = 2.2, the calculated takeoff speed V lof is 85.03m / s, and the angle of attack used in the calculation is α lof It is 9.21°.

[0068] The tail strike angle of the example aircraft is 11.5°. To ensure takeoff safety, the takeoff angle in the increased lift state is 9° to 10°.

[0069] Take off at the ground speed V lof Taking 85.03 m / s as the reference point, the calculation speed array [60 70 8090] is established, the take-off angle is 9°, and the residual lift at the take-off point in the four speed points in the lift-increasing state is calculated. The calculation data are shown in Table 1.

[0070] Table 1 Calculation data of residual lift at four speed points

[0071]

[0072]

[0073] Based on the data in Table 2, the calculation speed of gravity balance calculated by interpolation algorithm is 77.98 m / s.

[0074] Steps S3 and S4 are cyclic calculation steps. The speed calculated in step S2, 77.98 m / s, will be used as the initial input of step S3. Step S3 calculates the lift coefficient of the lift-off state, and then step S4 recalculates the lift-off speed according to the lift coefficient of the lift-off state. After three rounds of iterative calculations, the difference between the take-off speed of the cyclic input and the take-off speed of the cyclic output is less than 0.15%. The maximum lift coefficient available for take-off of the example aircraft is 2.666. The data of the calculation process are shown in Table 2 below.

[0075] Table 2 Calculation data of maximum lift coefficient available for takeoff

[0076]

[0077] In the above table, the angle of attack a lof-on The lift coefficient C under the lift-up state Lmax The relationship with the angle of attack is obtained by interpolation calculation.

[0078] In some optional implementations, in step S4, the takeoff speed V output by the cycle is calculated by the following formula: lof-on :

[0079]

[0080] Among them, C Lmax-on is the lift coefficient off the ground in the increased lift state, V s-on is the stall speed in the lifting state, V R-on V is the nose wheel lift speed during takeoff in the state of increased lift, 2-on It is the safe altitude speed in the ascending state.

[0081] The calculation results of this embodiment are shown in Table 3 below.

[0082] Table 3 Parameters related to calculation of characteristic takeoff speed in increased lift state

[0083]

[0084]

[0085] In a second aspect, the present application provides a transport aircraft takeoff characteristic speed determination device corresponding to the above method, which is applied to a lower surface blown flap powered lift transport aircraft, and the device comprises:

[0086] A non-powered lift state parameter determination module, used to determine the take-off speed and the angle of attack used in the non-powered lift state;

[0087] The module for determining the initial value of the lift state is used to select multiple take-off speeds near the take-off speed in the non-powered lift state, determine the corresponding residual lift, and interpolate the take-off speed V when the residual lift is 0. L0 ;

[0088] The lift coefficient calculation module is used to calculate the takeoff speed V L0 The take-off lift-off speed is used as the cyclic input of the enhanced lift state to calculate the lift coefficient of the enhanced lift state;

[0089] The loop control module is used to calculate the takeoff lift speed of the loop output according to the lift coefficient of the lift-off state, call the lift coefficient calculation module until the difference between the calculated takeoff lift speed of the loop input and the takeoff lift speed of the loop output is less than the set value, and calculate the stall speed of the lift-off state, the takeoff front wheel rotation speed and the safe altitude speed corresponding to the takeoff lift speed output by the loop at this time.

[0090] In some optional embodiments, in the non-powered lift state parameter determination module, the take-off speed V in the non-powered lift state is determined by the following formula: lof :

[0091]

[0092] Among them, C Lmax is the maximum lift coefficient of the takeoff configuration in the non-powered lift state, W to is the takeoff weight, ρ is the atmospheric density at the takeoff airport, S ref is the reference wing area of ​​the aircraft.

[0093] In some optional implementations, in the non-powered lift state parameter determination module, the use angle of attack of the non-powered lift state is determined by the following formula:

[0094]

[0095] α lof =interp1(CLsz,alphasz,C Llof );

[0096] Among them, interp1 is an interpolation function, which is used to interpolate the lift coefficient C in the corresponding relationship table constructed between the angle of attack array alphasz and the lift coefficient array CLsz of the takeoff configuration in the non-powered lift state. Llof The corresponding angle of attack α lof .

[0097] In some optional implementations, in the lift state initial value determination module, four lift-off speeds are selected at least in the vicinity of the take-off lift-off speed in the non-powered lift state with a step size of 5-10 m / s.

[0098] In some optional implementations, in the lift-increasing state initial value determination module, the remaining lift ΔZ is determined by the following formula:

[0099] ΔZ=L+Z p -W to g;

[0100] Where L = qS ref C Llof-on ; Z p =P xz η j sin(α lof +θ j );P xz =n e P emax (1-K s )K v K h ;n e is the number of engines, L is the lift force off the ground in the lift-up state, Z p is the component of thrust in the lift direction, P emax is the maximum thrust of the engine, K s is the system power extraction factor, K v is the speed correction factor for takeoff thrust, K h is the height correction factor, P xz is the takeoff thrust corrected for power and speed, η j is the engine jet efficiency factor, θ j is the downward deflection angle of the jet disturbed by the flap relative to the fuselage axis, and α is the calculated or selected operating angle of attack.

[0101] In some optional embodiments, in the cycle control module, the take-off speed V output by the cycle is calculated by the following formula: lof-on :

[0102]

[0103] Among them, C Lmax-on is the lift coefficient off the ground in the increased lift state, Vs-on is the stall speed in the lifting state, V R-on V is the nose wheel lift speed during takeoff in the state of increased lift, 2-on It is the safe altitude speed in the ascending state.

[0104] In a third aspect of the present application, a computer device includes a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement a method for determining a characteristic takeoff speed of a transport aircraft.

[0105] In a fourth aspect of the present application, a readable storage medium stores a computer program, and when the computer program is executed by a processor, it is used to implement the method for determining the characteristic takeoff speed of a transport aircraft as described above. The computer-readable storage medium may be included in the device described in the above embodiment; or it may exist independently without being assembled into the device. The computer-readable storage medium carries one or more programs, and when the one or more programs are executed by the device, the data is processed according to the above method.

[0106] Reference below Figure 2 , which shows a schematic structural diagram of a computer device 400 suitable for implementing the embodiments of the present application. Figure 2 The computer device shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present application.

[0107] like Figure 2 As shown, the computer device 400 includes a central processing unit (CPU) 401, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 402 or a program loaded from a storage part 408 into a random access memory (RAM) 403. In the RAM 403, various programs and data required for the operation of the device 400 are also stored. The CPU 401, the ROM 402, and the RAM 403 are connected to each other via a bus 404. An input / output (I / O) interface 405 is also connected to the bus 404.

[0108] The following components are connected to the I / O interface 405: an input section 406 including a keyboard, a mouse, etc.; an output section 407 including a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker, etc.; a storage section 408 including a hard disk, etc.; and a communication section 409 including a network interface card such as a LAN card, a modem, etc. The communication section 409 performs communication processing via a network such as the Internet. A drive 410 is also connected to the I / O interface 405 as needed. A removable medium 411, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed on the drive 410 as needed, so that a computer program read therefrom is installed into the storage section 408 as needed.

[0109] In particular, according to the embodiment of the present application, the process described above with reference to the flowchart can be implemented as a computer software program. For example, the embodiment of the present application includes a computer program product, which includes a computer program carried on a computer-readable medium, and the computer program includes a program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from the network through the communication part 409, and / or installed from the removable medium 411. When the computer program is executed by the central processing unit (CPU) 401, the above functions defined in the method of the present application are executed. It should be noted that the computer storage medium of the present application can be a computer-readable signal medium or a computer-readable storage medium or any combination of the above two. The computer-readable storage medium can be, for example, - but not limited to - a system, device or device of electricity, magnetism, light, electromagnetic, infrared, or semiconductor, or any combination of the above. More specific examples of computer-readable storage media may include, but are not limited to, an electrical connection with one or more conductors, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present application, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in combination with an instruction execution system, an apparatus or a device. In the present application, a computer-readable signal medium may include a data signal propagated in a baseband or as part of a carrier wave, which carries a computer-readable program code. Such propagated data signals may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. A computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium, which may send, propagate, or transmit a program for use by or in combination with an instruction execution system, an apparatus or a device. The program code contained on the computer-readable medium may be transmitted using any appropriate medium, including but not limited to: wireless, wire, optical cable, RF, etc., or any suitable combination of the above.

[0110] The flow chart and block diagram in the accompanying drawings illustrate the possible architecture, function and operation of the system, method and computer program product according to various embodiments of the present application. In this regard, each square box in the flow chart or block diagram can represent a module, a program segment or a part of a code, and the module, the program segment or a part of the code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some implementations as replacements, the functions marked in the square box can also occur in a sequence different from that marked in the accompanying drawings. For example, two square boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each square box in the block diagram and / or flow chart, and the combination of the square boxes in the block diagram and / or flow chart can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0111] The modules or units involved in the embodiments described in this application may be implemented by software or hardware. The modules or units described may also be set in a processor, and the names of these modules or units do not constitute limitations on the modules or units themselves in some cases.

[0112] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for determining the characteristic takeoff speed of a transport aircraft, applied to a power-lift transport aircraft with blown flaps on the lower surface, characterized in that: The method includes: Step S1, determining the take-off speed and the angle of attack in a non-powered lift state; Step S2: Select multiple take-off speeds near the take-off speed in the non-powered lift state, determine the corresponding residual lift, and interpolate and calculate the take-off speed V when the residual lift is 0. L0 ; Step S3: Take-off speed V L0 The take-off lift-off speed is used as the cyclic input of the enhanced lift state to calculate the lift coefficient of the enhanced lift state; Step S4, calculating the takeoff lift speed output by the loop according to the lift coefficient of the increased lift state, returning to step S3, until the difference between the calculated takeoff lift speed input by the loop and the takeoff lift speed output by the loop is less than the set value, calculating the increased lift state stall speed, takeoff nose wheel lifting speed and safe altitude speed corresponding to the takeoff lift speed output by the loop at this time.

2. The method for determining the characteristic takeoff speed of a transport aircraft according to claim 1, characterized in that: In step S1, the take-off speed V in the non-powered lift state is determined by the following formula: lof : Among them, C Lmax is the maximum lift coefficient of the takeoff configuration in the non-powered lift state, W to is the takeoff weight, ρ is the atmospheric density at the takeoff airport, S ref is the reference wing area of ​​the aircraft.

3. The method for determining the characteristic takeoff speed of a transport aircraft according to claim 1, characterized in that: In step S1, the angle of attack used in the non-powered lift state is determined by the following formula: α lof =interp1(CLsz,alphasz,C Llof ); Among them, interp1 is an interpolation function, which is used to interpolate the lift coefficient C in the corresponding relationship table constructed between the angle of attack array alphasz and the lift coefficient array CLsz of the takeoff configuration in the non-powered lift state. Llof The corresponding angle of attack α lof .

4. The method for determining the characteristic takeoff speed of a transport aircraft according to claim 1, wherein: In step S2, four take-off speeds are selected at least in the vicinity of the take-off speed in the non-powered lift state with a step length of 5-10 m / s.

5. The method for determining the characteristic takeoff speed of a transport aircraft according to claim 1, characterized in that: In step S2, the remaining lift ΔZ is determined by the following formula: ΔZ=L+Z p -W to g; Where L = qS ref C Llof-on ; Z p =P xz η j sin(α lof +θ j );P xz =n e P emax (1-K s )K v K h ;n e is the number of engines, L is the lift force off the ground in the lift-up state, Z p is the component of thrust in the lift direction, P emax is the maximum thrust of the engine, K s is the system power extraction factor, K v is the speed correction factor for takeoff thrust, K h is the height correction factor, P xz is the takeoff thrust corrected for power and speed, η j is the engine jet efficiency factor, θ j is the downward deflection angle of the jet disturbed by the flap relative to the fuselage axis, and α is the calculated or selected operating angle of attack.

6. The method for determining the characteristic takeoff speed of a transport aircraft according to claim 1, characterized in that: In step S4, the take-off speed V output by the loop is calculated by the following formula: lof-on : Among them, C Lmax-on is the lift coefficient off the ground in the increased lift state, V s-on is the stall speed in the lifting state, V R-on V is the nose wheel lift speed during takeoff in the state of increased lift, 2-on It is the safe altitude speed in the ascending state.

7. A transport aircraft takeoff characteristic speed determination device, applied to a lower surface blown flap powered lift transport aircraft, characterized in that: The device includes: A non-powered lift state parameter determination module, used to determine the take-off speed and the angle of attack used in the non-powered lift state; The module for determining the initial value of the lift state is used to select multiple take-off speeds near the take-off speed in the non-powered lift state, determine the corresponding residual lift, and interpolate the take-off speed V when the residual lift is 0. L0 ; The lift coefficient calculation module is used to calculate the takeoff speed V L0 The take-off lift-off speed is used as the cyclic input of the enhanced lift state to calculate the lift coefficient of the enhanced lift state; The loop control module is used to calculate the takeoff lift speed of the loop output according to the lift coefficient of the lift-off state, call the lift coefficient calculation module until the difference between the calculated takeoff lift speed of the loop input and the takeoff lift speed of the loop output is less than the set value, and calculate the stall speed of the lift-off state, the takeoff front wheel rotation speed and the safe altitude speed corresponding to the takeoff lift speed output by the loop at this time.

8. The transport aircraft takeoff characteristic speed determination device according to claim 7, characterized in that: In the non-powered lift state parameter determination module, the take-off speed V in the non-powered lift state is determined by the following formula: lof : Among them, C Lmax is the maximum lift coefficient of the takeoff configuration in the non-powered lift state, W to is the takeoff weight, ρ is the atmospheric density at the takeoff airport, S ref is the reference wing area of ​​the aircraft.

9. The transport aircraft takeoff characteristic speed determination device according to claim 7, characterized in that: In the non-powered lift state parameter determination module, the use angle of attack of the non-powered lift state is determined by the following formula: α lof =interp1(CLsz,alphasz,C Llof ); Among them, interp1 is an interpolation function, which is used to interpolate the lift coefficient C in the corresponding relationship table constructed between the angle of attack array alphasz and the lift coefficient array CLsz of the takeoff configuration in the non-powered lift state. Llof The corresponding angle of attack α lof .

10. The transport aircraft takeoff characteristic speed determination device according to claim 7, characterized in that: In the lift state initial value determination module, at least four lift-off speeds are selected in a step size of 5-10 m / s near the take-off lift speed in the non-powered lift state.

11. The transport aircraft takeoff characteristic speed determination device according to claim 7, characterized in that: In the lift-increasing state initial value determination module, the remaining lift ΔZ is determined by the following formula: ΔZ=L+Z p -W to g; Where L = qS ref C Llof-on ; Z p =P xz η j sin(α lof +θ j );P xz =n e P emax (1-K s )K v K h ;n e is the number of engines, L is the lift force off the ground in the lift-up state, Z p is the component of thrust in the lift direction, P emax is the maximum thrust of the engine, K s is the system power extraction factor, K v is the speed correction factor for takeoff thrust, K h is the height correction factor, P xz is the takeoff thrust corrected for power and speed, η j is the engine jet efficiency factor, θ j is the downward deflection angle of the jet disturbed by the flap relative to the fuselage axis, and α is the calculated or selected operating angle of attack.

12. The transport aircraft takeoff characteristic speed determination device according to claim 7, characterized in that: In the loop control module, the take-off speed V output by the loop is calculated by the following formula: lof-on : Among them, C Lmax-on is the lift coefficient off the ground in the increased lift state, V s-on is the stall speed in the lifting state, V R-on V is the nose wheel lift speed during takeoff in the state of increased lift, 2-on It is the safe altitude speed in the ascending state.

13. A computer device, characterized in that: The method comprises a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method for determining the characteristic takeoff speed of a transport aircraft as described in any one of claims 1 to 6.

14. A readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, it is used to implement the method for determining the characteristic takeoff speed of a transport aircraft as described in any one of claims 1 to 6.

Images