Method and apparatus for determining takeoff field length for a transport

Abstract

The application belongs to the technical field of take-off field performance design, and particularly relates to a method and device for determining the take-off field length of a transport aircraft, and is applied to a lower surface air-blowing flap powered lift transport aircraft. The method comprises the following steps: S1, determining the take-off thrust of the transport aircraft; S2, determining the acceleration of the transport aircraft and the path angle of the constant speed climb according to the take-off thrust; and S3, calculating the take-off field length of the transport aircraft according to an integral formula. The application can accurately simulate the influence of system power extraction, speed, height, jet flow efficiency and jet flow direction deflection on the take-off thrust, and can quickly and accurately calculate the length of the take-off field of the lower surface air-blowing flap powered lift transport aircraft in the case of single engine failure.

Description

Technical Field

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

[0002] Compared to conventional aircraft, the takeoff thrust, lift, and drag models for powered lift aircraft with blown flaps are much more complex. Takeoff thrust is closely related to speed, engine jet efficiency, and jet deflection angle. Lift is composed of two components: aerodynamic lift and jet flap interference lift. The aerodynamic lift coefficient is only related to the angle of attack and does not vary with speed, while the jet flap interference lift coefficient is highly sensitive to speed but not to the angle of attack. Jet flap interference lift is also independent of the speed-pressure relationship. The drag of powered lift aircraft with blown flaps exhibits the same characteristics. The dynamic models used to calculate takeoff field length for conventional aircraft cannot be applied to powered lift aircraft with blown flaps. Summary of the Invention

[0003] In order to solve the above problems, the present application provides a method and device for determining the take-off field length of a transport aircraft, providing technical support for determining the take-off field length of a transport aircraft with lower surface blown flaps and powered lift.

[0004] In a first aspect, the present application provides a method for determining the takeoff field length of a transport aircraft, which is applied to a powered high-lift transport aircraft with blown flaps on the lower surface. The method comprises:

[0005] Step S1: Determine the takeoff thrust P of the transport aircraft xzon ;

[0006] Step S2: According to the takeoff thrust P xzon Determine the transport aircraft's acceleration a and the flight path angle θ for a constant-speed climb;

[0007] Step S3: Calculate the takeoff field length L of the transport aircraft according to the following integral formula:

[0008]

[0009] Among them, L R L is the ground rolling distance before lifting the front wheel for takeoff. L-R L is the rolling distance between the front wheel lift and the departure point, C is the flight distance to climb to a safe altitude, V is the speed, V S is the takeoff configuration stall speed, V R is the front wheel speed, V lof is the ground speed.

[0010] Preferably, in step S1, the takeoff thrust P is determined by the following formula: xzon :

[0011]

[0012] Among them, n e is the number of engines, P emax is the maximum thrust of the engine at takeoff, K s is the takeoff system power extraction factor, K v is the speed correction factor for takeoff thrust, K h is the altitude correction factor for takeoff thrust, P xz is the available thrust for takeoff 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 fuselage angle of attack.

[0013] Preferably, step S2 further comprises:

[0014] Step S21: Determine the takeoff lift coefficient C in the increased lift state L ;

[0015] Step S22: Determine the takeoff drag coefficient C in the increased lift state D ;

[0016] Step S23: Determine the acceleration a of the transport aircraft using the following formula:

[0017]

[0018] Where W is the takeoff weight of the aircraft, D is the takeoff aerodynamic drag, L is the takeoff aerodynamic lift, F is the friction force of the runway, f is the rolling friction coefficient of the runway, and Z is the takeoff weight of the aircraft. p is the component of thrust in the lift direction, S ref is the wing reference area, ρ is the air density, and q is the velocity pressure;

[0019] Step S24: Determine the track angle θ of the constant speed climb using the following formula:

[0020]

[0021] Preferably, step S21 further includes:

[0022] Step S211: Determine the lift coefficient correction value ΔC of the jet flap flow Lb ;

[0023] Step S212: Determine the lift coefficient correction value ΔC of the jet vector effect Lp ;

[0024] Step S213: Determine the takeoff lift coefficient C in the increased lift state using the following formula: L :

[0025] C L =C Loff +ΔC Lb +ΔC Lp ;

[0026] Among them, C Loff It is the takeoff lift coefficient in the non-powered lift state.

[0027] Preferably, in step S211, the lift coefficient correction value ΔC of the jet flap flow is determined by the following formula: Lb :

[0028] ΔC Lb =ΔC Lθ +ΔC Lα ;

[0029] Where, ΔC Lθ is the base value of the lift coefficient dynamic effect correction; ΔC Lα is the correction amount of the lift coefficient increment corresponding to the angle of attack α.

[0030] Preferably, in step S212, the lift coefficient correction value ΔC of the jet vector effect is determined by the following formula: Lp :

[0031]

[0032] Among them, C T is the aircraft takeoff thrust coefficient.

[0033] Preferably, in step S22, the takeoff drag coefficient C in the increased lift state is determined by the following formula: D :

[0034] C D =C Doff +ΔC D ;

[0035] Among them, C Doff is the drag coefficient in the non-powered lift state, ΔC D is the dynamic effect correction of the drag coefficient.

[0036] Preferably, in step S23, when the takeoff thrust coefficient of the aircraft exceeds 5.6, the takeoff aerodynamic drag D and the takeoff aerodynamic lift L of the aircraft are determined by the following steps:

[0037] Step S231: Determine the lift correction amount and the drag correction amount at multiple speed points with a thrust coefficient between 0.26 and 5.6, and fit the quadratic function of the lift correction amount and the speed, and the quadratic function of the drag correction amount and the speed, respectively;

[0038] Step S232: Determine the lift correction amount and the drag correction amount according to the current speed of the transport aircraft, and then determine the takeoff aerodynamic drag D and the takeoff aerodynamic lift L of the aircraft.

[0039] A second aspect of the present application provides a device for determining the takeoff field length of a transport aircraft, which is applied to a power-lift transport aircraft with blown flaps on the lower surface. The device comprises:

[0040] Takeoff thrust determination module, used to determine the takeoff thrust P of the transport aircraft xzon ;

[0041] Acceleration and track angle determination module, used to determine the takeoff thrust P xzon Determine the transport aircraft's acceleration a and the flight path angle θ for a constant-speed climb;

[0042] The takeoff field length determination module is used to calculate the takeoff field length L of the transport aircraft according to the following integral formula:

[0043]

[0044] Among them, L R L is the ground rolling distance before lifting the front wheel for takeoff. L-R L is the rolling distance between the front wheel lift and the departure point, C is the flight distance to climb to a safe altitude, V is the speed, V S is the takeoff configuration stall speed, V R is the front wheel speed, V lof is the ground speed.

[0045] Preferably, in the takeoff thrust determination module, the takeoff thrust P is determined by the following formula: xzon :

[0046]

[0047] Among them, n e is the number of engines, P emax is the maximum thrust of the engine at takeoff, K s is the takeoff system power extraction factor, K v is the speed correction factor for takeoff thrust, K h is the altitude correction factor for takeoff thrust, P xz is the available thrust for takeoff 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 fuselage angle of attack.

[0048] Preferably, the acceleration and track angle determination module includes:

[0049] Takeoff lift coefficient determination unit, used to determine the takeoff lift coefficient C in the increased lift state L ;

[0050] Takeoff drag coefficient determination unit, used to determine the takeoff drag coefficient C in the increased lift state D ;

[0051] The acceleration determination unit is used to determine the acceleration a of the conveyor by using the following formula:

[0052]

[0053] Where W is the takeoff weight of the aircraft, D is the takeoff aerodynamic drag, L is the takeoff aerodynamic lift, F is the friction force of the runway, f is the rolling friction coefficient of the runway, and Z is the takeoff weight of the aircraft. p is the component of thrust in the lift direction, S ref is the wing reference area, ρ is the air density, and q is the velocity pressure;

[0054] The track angle determination unit is used to determine the track angle θ of the constant speed climb using the following formula:

[0055]

[0056] Preferably, the takeoff lift coefficient determination unit includes:

[0057] The first lift coefficient correction determination subunit is used to determine the lift coefficient correction ΔC of the jet flap flow. Lb ;

[0058] The second lift coefficient correction value determination subunit is used to determine the lift coefficient correction value ΔC of the jet vector effect Lp ;

[0059] The takeoff lift coefficient calculation subunit is used to determine the takeoff lift coefficient C in the increased lift state using the following formula L :

[0060] C L =C Loff +ΔC Lb +ΔC Lp ;

[0061] Among them, C Loff It is the takeoff lift coefficient in the non-powered lift state.

[0062] Preferably, in the first lift coefficient correction amount determination subunit, the lift coefficient correction amount ΔC of the jet flap flow is determined by the following formula: Lb :

[0063] ΔC Lb =ΔC Lθ +ΔCLα ;

[0064] Where, ΔC Lθ is the base value of the lift coefficient dynamic effect correction; ΔC Lα is the correction amount of the lift coefficient increment corresponding to the angle of attack α.

[0065] Preferably, in the second lift coefficient correction amount determination subunit, the lift coefficient correction amount ΔC of the jet vector effect is determined by the following formula: Lp :

[0066]

[0067] Among them, C T is the aircraft takeoff thrust coefficient.

[0068] Preferably, in the takeoff drag coefficient determining unit, the takeoff drag coefficient C in the increased lift state is determined by the following formula: D :

[0069] C D =C Doff +ΔC D ;

[0070] Among them, C Doff is the drag coefficient in the non-powered lift state, ΔC D is the dynamic effect correction of the drag coefficient.

[0071] Preferably, in the acceleration determination unit, when the takeoff thrust coefficient of the aircraft exceeds 5.6, the takeoff aerodynamic drag D and the takeoff aerodynamic lift L of the aircraft are reconstructed by the following modules:

[0072] The quadratic function construction subunit is used to determine the lift correction and drag correction at multiple speed points with a thrust coefficient between 0.26 and 5.6, and to fit the quadratic functions of the lift correction and speed, and the drag correction and speed respectively;

[0073] The lift and drag reconstruction subunit is used to determine the lift correction amount and the drag correction amount according to the current speed of the transport aircraft, and then determine the takeoff aerodynamic drag D and takeoff aerodynamic lift L of the aircraft.

[0074] 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 length of a transport aircraft takeoff field as described above.

[0075] A fourth aspect of the present application provides a readable storage medium, wherein the 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 length of the transport aircraft takeoff field as described above.

[0076] The present application can accurately simulate the effects of system power extraction, speed, altitude, jet efficiency, and jet direction deflection on takeoff thrust, and can quickly and accurately calculate the length of the single-engine failure takeoff field for a lower-surface blown flap powered lift transport aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 It is a flow chart of a preferred embodiment of the method for determining the length of the transport aircraft takeoff field of the present application.

[0078] Figure 2 It is a structural diagram of a computer device suitable for implementing the embodiments of the present application. DETAILED DESCRIPTION

[0079] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the implementation of this application will be described in more detail below in conjunction with the drawings in the implementation of this application. In the drawings, the same or similar numbers 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 should not 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 conjunction with the drawings.

[0080] The first aspect of the present application provides a method for determining the takeoff field length of a transport aircraft, which is applied to a power-lift transport aircraft with blown flaps on the lower surface, such as Figure 1 As shown, the method mainly includes:

[0081] Step S1: Determine the takeoff thrust P of the transport aircraft xzon ;

[0082] Step S2: According to the takeoff thrust P xzon Determine the transport aircraft's acceleration a and the flight path angle θ for a constant-speed climb;

[0083] Step S3: Calculate the takeoff field length L of the transport aircraft according to the following integral formula:

[0084]

[0085] Among them, L RL is the ground rolling distance before lifting the front wheel for takeoff. L-R L is the rolling distance between the front wheel lift and the departure point, C is the flight distance to climb to a safe altitude, V is the speed, V S is the takeoff configuration stall speed, V R is the front wheel speed, V lof is the ground speed.

[0086] The present application first calculates takeoff thrust in step S1. Based on this, the transport aircraft's acceleration a and the flight path angle θ for a constant-speed climb are calculated in step S2. Finally, in step S3, the velocity V is integrated based on the transport aircraft's acceleration a to obtain the distance the transport aircraft has traveled on the ground, i.e., the first runway length. The flight altitude is then integrated based on the flight path angle to determine the second runway length required within the safe altitude range. The two runway lengths are then combined to form the minimum required takeoff field length. This length can guide takeoff field design and can also be used to optimize aircraft parameters based on existing takeoff fields.

[0087] In some optional embodiments, in step S1, the takeoff thrust P is determined by the following formula: xzon :

[0088]

[0089] Among them, n e is the number of engines, P emax is the maximum thrust of the engine at takeoff, K s is the takeoff system power extraction factor, K v is the speed correction factor for takeoff thrust, K h is the altitude correction factor for takeoff thrust, P xz is the available thrust for takeoff 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 fuselage angle of attack.

[0090] In this embodiment, the engine jet efficiency factor η j The calculation model is:

[0091]

[0092] Among them, θ jc is the theoretical deflection angle of the engine jet caused by flap interference. The calculation model is as follows:

[0093] (1) When λ1=1, and θ d =0, θ jc =0;

[0094] (2) When λ1=1, θ jc =θ d ;

[0095] (3) In other cases,

[0096] Among them, when F<1.0, When F ≥ 1.0, λ1 = 1;

[0097] in, Y=1-2F;λ2=interp1(θ m sz,λ2sz,θ m );

[0098]

[0099] Where F is the jet immersion factor of the flap, H f is the jet immersion depth of the flap, θ m is the downward deflection angle of the flap relative to the engine axis, θ d is the deflection angle of the engine jet disturbed by the flap, λ2 is θ m function, interp1 is the interpolation function.

[0100] The deflection angle θ of the engine jet affected by the flap d and the downward deflection angle θ of the jet flow disturbed by the flap relative to the fuselage axis j The calculation model is as follows:

[0101]

[0102] Where δ f is the flap downward deflection angle, θ fte is the angle between the upper surface of the flap trailing edge point and the flap chord, θ ew is the downward angle of the engine axis relative to the wing chord line, θ m is the downward deflection angle of the flap relative to the engine axis, θ d is the deflection angle of the jet disturbed by the flap, θ jw is the downward deflection angle of the engine jet relative to the wing chord line, θ wi The installation angle of the wing section at the engine installation location.

[0103] In some optional embodiments, step S2 further includes:

[0104] Step S21: Determine the takeoff lift coefficient C in the increased lift state L ;

[0105] Step S22: Determine the takeoff drag coefficient C in the increased lift state D ;

[0106] Step S23: Determine the acceleration a of the transport aircraft using the following formula:

[0107]

[0108] Where W is the takeoff weight of the aircraft, D is the takeoff aerodynamic drag, L is the takeoff aerodynamic lift, F is the friction force of the runway, f is the rolling friction coefficient of the runway, and Z is the takeoff weight of the aircraft. p is the component of thrust in the lift direction, S ref is the wing reference area, ρ is the air density, and q is the velocity pressure;

[0109] Step S24: Determine the track angle θ of the constant speed climb using the following formula:

[0110]

[0111] In some optional implementations, step S21 further includes:

[0112] Step S211: Determine the lift coefficient correction value ΔC of the jet flap flow Lb ;

[0113] Step S212: Determine the lift coefficient correction value ΔC of the jet vector effect Lp ;

[0114] Step S213: Determine the takeoff lift coefficient C in the increased lift state using the following formula: L :

[0115] C L =C Loff +ΔC Lb +ΔC Lp ;

[0116] Among them, C Loff It is the takeoff lift coefficient in the non-powered lift state.

[0117] In some optional embodiments, in step S211, the lift coefficient correction value ΔC of the jet flap flow is determined by the following formula: Lb :

[0118] ΔC Lb =ΔC Lθ +ΔC Lα ;

[0119] Where, ΔC Lθ is the base value of the lift coefficient dynamic effect correction; ΔC Lα is the correction amount of the lift coefficient increment corresponding to the angle of attack α.

[0120] In this embodiment, the reference value ΔC of the lift coefficient dynamic influence correction amount isLθ The calculation model is:

[0121]

[0122] Among them, C μ is the engine tail jet momentum coefficient, φ is the span factor affected by the jet, K1 is a function of the momentum coefficient, G is a function of the wing aspect ratio AR and parameter K2, K2 is the ratio of the flap extended chord length to the original chord length; θ f is the downward deflection angle of the upper surface of the trailing edge of the second flap relative to the chord, θ faux c is the downward angle of the chord line of the second flap relative to the chord line of the front flap; f is the sum of the chord lengths of the two flaps, c faux is the chord length of the second flap, c' is the chord length of the wing after the flaps are extended, and c is the chord length of the wing before the flaps are extended. K 3aux and K3 are functions of the momentum coefficient and the relative chord length of the flap.

[0123] In this embodiment, the correction amount ΔC of the lift coefficient increment corresponding to the angle of attack α is Lα The calculation model is:

[0124]

[0125] Among them, θ wi is the installation angle of the engine axis relative to the wing section relative to the fuselage axis, The relative thickness of the wing with flaps extended.

[0126] In some optional embodiments, in step S212, the lift coefficient correction value ΔC of the jet vector effect is determined by the following formula: Lp :

[0127]

[0128] Among them, C T is the aircraft takeoff thrust coefficient.

[0129] In some optional embodiments, in step S22, the takeoff drag coefficient C in the increased lift state is determined by the following formula: D :

[0130] C D =C Doff +ΔC D ;

[0131] Among them, C Doff is the drag coefficient in the non-powered lift state, ΔC D is the dynamic effect correction of the drag coefficient.

[0132] In this embodiment, the dynamic influence correction amount ΔC of the drag coefficient is D The calculation model is:

[0133]

[0134] In some optional embodiments, in step S23, when the takeoff thrust coefficient of the aircraft exceeds 5.6, the takeoff aerodynamic drag D and the takeoff aerodynamic lift L of the aircraft are determined by the following steps:

[0135] Step S231: Determine the lift correction amount and the drag correction amount at multiple speed points with a thrust coefficient between 0.26 and 5.6, and fit the quadratic function of the lift correction amount and the speed, and the quadratic function of the drag correction amount and the speed, respectively;

[0136] Step S232: Determine the lift correction amount and the drag correction amount according to the current speed of the transport aircraft, and then determine the takeoff aerodynamic drag D and the takeoff aerodynamic lift L of the aircraft.

[0137] In this embodiment, the calculation model for the dynamic impact correction of the lift coefficient and drag coefficient can only be used in the speed range where the thrust coefficient is less than 5.6. Because the speed is low and the thrust coefficient is large during the initial takeoff phase, this application uses the above method to reconstruct the calculation method for takeoff aerodynamic drag D and takeoff aerodynamic lift L when the takeoff thrust coefficient exceeds 5.6.

[0138] In this embodiment, the lift and drag correction values ​​in the low speed region are calculated by data fitting. In step S231, the correction values ​​of the lift and drag dynamic effects at multiple speed points with a thrust coefficient between 0.26 and 5.6 are first determined. The calculation model is shown in the formula:

[0139]

[0140] Afterwards, a fitting algorithm is used to construct a quadratic function of the lift and drag dynamic effect correction with respect to speed:

[0141]

[0142] Finally, in step S232 , new takeoff aerodynamic drag D and takeoff aerodynamic lift L are calculated.

[0143] The example aircraft uses the lower surface blown flap power lift technology, and the aircraft reference wing area is 353m 2The aircraft has a wingspan of 50.6m, an aspect ratio of 7.25, a quarter-chord sweep angle of 21°, and a tip-to-root ratio of 0.24. Four high-bypass turbofan engines, each with a thrust of 185 kN, are suspended from the wings. The engine thrust axes are angled -5° relative to the local wing chord. The inboard engines are mounted at 29.6% of half-span, with a 3° wing section angle. The outboard engines are mounted at 55% of half-span, with a 2.5° wing section angle.

[0144] Takeoff configuration: Leading-edge slats with a deflection angle of 15°, trailing-edge double-slotted Fuller flaps with a deflection angle of 15° + 10°, and an 8° downward inclination on the upper surface of the flap trailing edge. With the flaps extended, the chord length of the wing is 1.2 times the original chord length, with the flap chord length being 32% of the chord length, of which the chord length of the second flap section is 7% of the chord length. The depth of the inboard flap portion immersed in the engine jet is 2.33m, the diameter of the jet at the flap trailing edge is 5.43m, and the local wing chord length is 8.73m. The depth of the outboard flap portion immersed in the engine jet is 2.1m, the diameter of the jet at the flap trailing edge is 4.89m, and the local wing chord length is 6.48m.

[0145] Calculation status: takeoff weight 265t, system power extraction factor Ks 3.6%, calculation model of speed correction factor Speed ​​correction factor K h Take 1; the takeoff nose wheel speed is 76.27 m / s, the liftoff speed and the safety altitude speed are 82.08 m / s, and the takeoff angle of attack is 8°. The calculation process of the dynamic simulation of the example aircraft takeoff is as follows:

[0146] (1) Engine jet downward deflection angle θ relative to the fuselage axis j Calculated to be 12.25°;

[0147] (2) Theoretical deflection angle θ of the engine jet caused by flap interference jc Calculated to be 38.1°;

[0148] (3) Engine jet efficiency factor η j Calculated to be 0.907;

[0149] (4) The quadratic function of the takeoff aerodynamic drag D determined in step S231 with respect to speed is:

[0150] ΔD=-0.0073319V2+0.68819V;

[0151] The quadratic function of the determined takeoff aerodynamic lift L with respect to speed is:

[0152] ΔL=-0.057942V2+7.0166V.

[0153] Finally, simulation calculations were performed, as shown in Table 1 below. The calculated data shows: the target aircraft's takeoff field length is 2364 meters, the climb path angle is 4.97°, the acceleration is shown in the 5th column, the takeoff thrust is shown in the 6th column, the lift in the unpowered lift state is shown in the 7th column, the dynamic correction for lift is shown in the 8th column, the lift-direction component of the thrust is shown in the 9th column, the drag in the unpowered lift state is shown in the 10th column, the dynamic correction for drag is shown in the 11th column, and the frictional resistance is shown in the 12th column.

[0154] Table 1. Calculation data of takeoff dynamics simulation of target aircraft

[0155]

[0156] In Table 1 above, a lot of data is omitted between the third and fourth rows.

[0157] A second aspect of the present application provides a transport aircraft takeoff field length determination device corresponding to the above method, which is applied to a power-assisted high-lift transport aircraft with blown flaps on the lower surface. The device comprises:

[0158] Takeoff thrust determination module, used to determine the takeoff thrust P of the transport aircraft xzon ;

[0159] Acceleration and track angle determination module, used to determine the takeoff thrust P xzon Determine the transport aircraft's acceleration a and the flight path angle θ for a constant-speed climb;

[0160] The takeoff field length determination module is used to calculate the takeoff field length L of the transport aircraft according to the following integral formula:

[0161]

[0162] Among them, L R L is the ground rolling distance before lifting the front wheel for takeoff. L-R L is the rolling distance between the front wheel lift and the departure point, C is the flight distance to climb to a safe altitude, V is the speed, V S is the takeoff configuration stall speed, V R is the front wheel speed, V lof is the ground speed.

[0163] In some optional embodiments, in the takeoff thrust determination module, the takeoff thrust P is determined by the following formula: xzon :

[0164]

[0165] Among them, n e is the number of engines, P emax is the maximum thrust of the engine at takeoff, K sis the takeoff system power extraction factor, K v is the speed correction factor for takeoff thrust, K h is the altitude correction factor for takeoff thrust, P xz is the available thrust for takeoff 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 fuselage angle of attack.

[0166] In some optional implementations, the acceleration and track angle determination module includes:

[0167] Takeoff lift coefficient determination unit, used to determine the takeoff lift coefficient C in the increased lift state L ;

[0168] Takeoff drag coefficient determination unit, used to determine the takeoff drag coefficient C in the increased lift state D ;

[0169] The acceleration determination unit is used to determine the acceleration a of the conveyor by using the following formula:

[0170]

[0171] Where W is the takeoff weight of the aircraft, D is the takeoff aerodynamic drag, L is the takeoff aerodynamic lift, F is the friction force of the runway, f is the rolling friction coefficient of the runway, and Z is the takeoff weight of the aircraft. p is the component of thrust in the lift direction, S ref is the wing reference area, ρ is the air density, and q is the velocity pressure;

[0172] The track angle determination unit is used to determine the track angle θ of the constant speed climb using the following formula:

[0173]

[0174] In some optional embodiments, the takeoff lift coefficient determination unit includes:

[0175] The first lift coefficient correction determination subunit is used to determine the lift coefficient correction ΔC of the jet flap flow. Lb ;

[0176] The second lift coefficient correction value determination subunit is used to determine the lift coefficient correction value ΔC of the jet vector effect Lp ;

[0177] The takeoff lift coefficient calculation subunit is used to determine the takeoff lift coefficient C in the increased lift state using the following formula L :

[0178] C L =CLoff +ΔC Lb +ΔC Lp ;

[0179] Among them, C Loff It is the takeoff lift coefficient in the non-powered lift state.

[0180] In some optional embodiments, in the first lift coefficient correction amount determination subunit, the lift coefficient correction amount ΔC of the jet flap flow is determined by the following formula: Lb :

[0181] ΔC Lb =ΔC Lθ +ΔC Lα ;

[0182] Where, ΔC Lθ is the base value of the lift coefficient dynamic effect correction; ΔC Lα is the correction amount of the lift coefficient increment corresponding to the angle of attack α.

[0183] In some optional embodiments, in the second lift coefficient correction amount determination subunit, the lift coefficient correction amount ΔC of the jet vector effect is determined by the following formula: Lp :

[0184]

[0185] Among them, C T is the aircraft takeoff thrust coefficient.

[0186] In some optional embodiments, in the takeoff drag coefficient determination unit, the takeoff drag coefficient C in the increased lift state is determined by the following formula: D :

[0187] C D =C Doff +ΔC D ;

[0188] Among them, C Doff is the drag coefficient in the non-powered lift state, ΔC D is the dynamic effect correction of the drag coefficient.

[0189] In some optional embodiments, in the acceleration determination unit, when the takeoff thrust coefficient of the aircraft exceeds 5.6, the takeoff aerodynamic drag D and the takeoff aerodynamic lift L of the aircraft are reconstructed by the following modules:

[0190] The quadratic function construction subunit is used to determine the lift correction and drag correction at multiple speed points with a thrust coefficient between 0.26 and 5.6, and to fit the quadratic functions of the lift correction and speed, and the drag correction and speed respectively;

[0191] The lift and drag reconstruction subunit is used to determine the lift correction amount and the drag correction amount according to the current speed of the transport aircraft, and then determine the takeoff aerodynamic drag D and takeoff aerodynamic lift L of the aircraft.

[0192] 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 the length of a transport aircraft takeoff field.

[0193] In a fourth aspect, the present application provides a readable storage medium storing a computer program that, when executed by a processor, implements the method for determining the length of a transport aircraft takeoff field described above. The computer-readable storage medium may be included in the apparatus described in the above embodiments, or it may exist independently and not be incorporated into the apparatus. The computer-readable storage medium carries one or more programs, and when executed by the apparatus, the one or more programs process data according to the method described above.

[0194] Reference below Figure 2 , which shows a 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 limit the functions and scope of use of the embodiments of the present application.

[0195] like Figure 2 As shown, 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 portion 408 into a random access memory (RAM) 403. Various programs and data required for the operation of device 400 are also stored in RAM 403. CPU 401, ROM 402, and RAM 403 are connected to each other via a bus 404. An input / output (I / O) interface 405 is also connected to bus 404.

[0196] The following components are connected to the I / O interface 405: an input section 406 including a keyboard, a mouse, and the like; an output section 407 including devices such as a cathode ray tube (CRT), a liquid crystal display (LCD), and a speaker; a storage section 408 including a hard disk; and a communication section 409 including a network interface card such as a LAN card or a modem. 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. Removable media 411, such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory, is installed in the drive 410 as needed, so that computer programs read therefrom can be installed into the storage section 408 as needed.

[0197] 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 component 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 having one or more conductors, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In this application, a computer-readable storage medium may be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. In this application, a computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, which carries computer-readable program code. Such a propagated data signal may take a variety of forms, including, but not limited to, electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium that can transmit, propagate, or transfer a program for use by or in conjunction with an instruction execution system, apparatus, or device. The program code embodied on a computer-readable medium may be transmitted using any suitable medium, including, but not limited to, wireless, wire, optical cable, RF, etc., or any suitable combination thereof.

[0198] The flow charts and block diagrams in the accompanying drawings illustrate the possible architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present application. In this regard, each box in the flow chart or block diagram can represent a module, program segment or a part of code, and the module, program segment or a part of code includes one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a sequence different from that marked in the accompanying drawings. For example, two 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 box in the block diagram and / or flow chart, and the combination of the boxes in the block diagram and / or flow chart can be implemented by a dedicated hardware-based system that performs the specified function or operation, or can be implemented by a combination of dedicated hardware and computer instructions.

[0199] The modules or units described in the embodiments of this application may be implemented in software or hardware. The modules or units described may also be provided in a processor, and the names of these modules or units do not, in certain circumstances, limit the modules or units themselves.

[0200] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for determining the takeoff field length of a transport aircraft, applied to a powered lift transport aircraft with blown flaps on the lower surface, characterized in that: The method includes: Step S1: Determine the takeoff thrust P of the transport aircraft xzon ; Step S2: According to the takeoff thrust P xzon Determine the transport aircraft's acceleration a and the flight path angle θ for a constant-speed climb; Step S3: Calculate the takeoff field length L of the transport aircraft according to the following integral formula: Among them, L R L is the ground rolling distance before lifting the front wheel for takeoff. L-R L is the rolling distance between the front wheel lift and the departure point, C is the flight distance to climb to a safe altitude, V is the speed, V S is the takeoff configuration stall speed, V R is the front wheel speed, V lof is the lift-off speed; Wherein, step S2 further includes: Step S21: Determine the takeoff lift coefficient C in the increased lift state L ; Step S22: Determine the takeoff drag coefficient C in the increased lift state D ; Step S23: Determine the acceleration a of the transport aircraft using the following formula: Where W is the takeoff weight of the aircraft, D is the takeoff aerodynamic drag, L is the takeoff aerodynamic lift, F is the friction force of the runway, f is the rolling friction coefficient of the runway, and Z is the takeoff weight of the aircraft. p is the component of thrust in the lift direction, S ref is the wing reference area, ρ is the air density, and q is the velocity pressure; Step S24: Determine the track angle θ of the constant speed climb using the following formula:

2. The method for determining the length of a transport aircraft takeoff field according to claim 1, wherein: In step S1, the takeoff thrust P is determined by the following formula: xzon : Among them, n e is the number of engines, P emax is the maximum thrust of the engine at takeoff, K s is the takeoff system power extraction factor, K v is the speed correction factor for takeoff thrust, K h is the altitude correction factor for takeoff thrust, P xz is the available thrust for takeoff 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 fuselage angle of attack.

3. The method for determining the length of a transport aircraft takeoff field according to claim 1, wherein: Step S21 further includes: Step S211: Determine the lift coefficient correction value ΔC of the jet flap flow Lb ; Step S212: Determine the lift coefficient correction value ΔC of the jet vector effect Lp ; Step S213: Determine the takeoff lift coefficient C in the increased lift state using the following formula: L : C L =C Loff +△C Lb +△C Lp ; Among them, C Loff It is the takeoff lift coefficient in the non-powered lift state.

4. The method for determining the length of a transport aircraft takeoff field according to claim 3, wherein: In step S211, the lift coefficient correction value ΔC of the jet flap flow is determined by the following formula: Lb : △C Lb =△C Lθ +△C Lα ; Among them, △C Lθ is the reference value of the dynamic effect correction of the lift coefficient; △C Lα is the correction amount of the lift coefficient increment corresponding to the angle of attack α.

5. The method for determining the length of a transport aircraft takeoff field according to claim 3, wherein: In step S212, the lift coefficient correction value ΔC of the jet vector effect is determined by the following formula: Lp : Among them, C T is the aircraft takeoff thrust coefficient.

6. The method for determining the length of a transport aircraft takeoff field according to claim 1, wherein: In step S22, the takeoff drag coefficient C in the increased lift state is determined by the following formula: D : C D =C Doff +△C D ; Among them, C Doff is the drag coefficient in the non-powered lift state, △C D is the dynamic effect correction of the drag coefficient.

7. The method for determining the length of a transport aircraft takeoff field according to claim 1, wherein: In step S23, when the takeoff thrust coefficient of the aircraft exceeds 5.6, the takeoff aerodynamic drag D and the takeoff aerodynamic lift L of the aircraft are determined by the following steps: Step S231: Determine the lift correction amount and the drag correction amount at multiple speed points with a thrust coefficient between 0.26 and 5.6, and fit the quadratic function of the lift correction amount and the speed, and the quadratic function of the drag correction amount and the speed, respectively; Step S232: Determine the lift correction amount and the drag correction amount according to the current speed of the transport aircraft, and then determine the takeoff aerodynamic drag D and the takeoff aerodynamic lift L of the aircraft.

8. A device for determining the takeoff field length of a transport aircraft, applied to a power-lift transport aircraft with blown flaps on the lower surface, characterized in that: The device includes: Takeoff thrust determination module, used to determine the takeoff thrust P of the transport aircraft xzon ; Acceleration and track angle determination module, used to determine the takeoff thrust P xzon Determine the transport aircraft's acceleration a and the flight path angle θ for a constant-speed climb; The takeoff field length determination module is used to calculate the takeoff field length L of the transport aircraft according to the following integral formula: Among them, L R L is the ground rolling distance before lifting the front wheel for takeoff. L-R L is the rolling distance between the front wheel lift and the departure point, C is the flight distance to climb to a safe altitude, V is the speed, V S is the takeoff configuration stall speed, V R is the front wheel speed, V lof is the lift-off speed; The acceleration and track angle determination module includes: Takeoff lift coefficient determination unit, used to determine the takeoff lift coefficient C in the increased lift state L ; Takeoff drag coefficient determination unit, used to determine the takeoff drag coefficient C in the increased lift state D ; The acceleration determination unit is used to determine the acceleration a of the conveyor by using the following formula: Where W is the takeoff weight of the aircraft, D is the takeoff aerodynamic drag, L is the takeoff aerodynamic lift, F is the friction force of the runway, f is the rolling friction coefficient of the runway, and Z is the takeoff weight of the aircraft. p is the component of thrust in the lift direction, S ref is the wing reference area, ρ is the air density, and q is the velocity pressure; The track angle determination unit is used to determine the track angle θ of the constant speed climb using the following formula:

9. The device for determining the length of a transport aircraft takeoff field according to claim 8, wherein: In the takeoff thrust determination module, the takeoff thrust P is determined by the following formula: xzon : Among them, n e is the number of engines, P emax is the maximum thrust of the engine at takeoff, K s is the takeoff system power extraction factor, K v is the speed correction factor for takeoff thrust, K h is the altitude correction factor for takeoff thrust, P xz is the available thrust for takeoff 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 fuselage angle of attack.

10. The device for determining the length of a transport aircraft takeoff field according to claim 8, wherein: The takeoff lift coefficient determination unit includes: The first lift coefficient correction determination subunit is used to determine the lift coefficient correction ΔC of the jet flap flow. Lb ; The second lift coefficient correction value determination subunit is used to determine the lift coefficient correction value △C of the jet vector effect Lp ; The takeoff lift coefficient calculation subunit is used to determine the takeoff lift coefficient C in the increased lift state using the following formula L : C L =C Loff +△C Lb +△C Lp ; Among them, C Loff It is the takeoff lift coefficient in the non-powered lift state.

11. The device for determining the length of a transport aircraft takeoff field according to claim 10, wherein: In the first lift coefficient correction amount determination subunit, the lift coefficient correction amount ΔC of the jet flap flow is determined by the following formula: Lb : △C Lb =△C Lθ +△C Lα ; Among them, △C Lθ is the reference value of the dynamic effect correction of the lift coefficient; △C Lα is the correction amount of the lift coefficient increment corresponding to the angle of attack α.

12. The device for determining the length of a transport aircraft takeoff field according to claim 10, wherein: In the second lift coefficient correction amount determination subunit, the lift coefficient correction amount ΔC of the jet vector effect is determined by the following formula: Lp : Among them, C T is the aircraft takeoff thrust coefficient.

13. The device for determining the length of a transport aircraft takeoff field according to claim 8, wherein: In the takeoff drag coefficient determination unit, the takeoff drag coefficient C in the increased lift state is determined by the following formula: D : C D =C Doff +△C D ; Among them, C Doff is the drag coefficient in the non-powered lift state, △C D is the dynamic effect correction of the drag coefficient.

14. The device for determining the length of a transport aircraft takeoff field according to claim 8, wherein: In the acceleration determination unit, when the takeoff thrust coefficient of the aircraft exceeds 5.6, the takeoff aerodynamic drag D and the takeoff aerodynamic lift L of the aircraft are reconstructed through the following modules: The quadratic function construction subunit is used to determine the lift correction and drag correction at multiple speed points with a thrust coefficient between 0.26 and 5.6, and to fit the quadratic functions of the lift correction and speed, and the drag correction and speed respectively; The lift and drag reconstruction subunit is used to determine the lift correction amount and the drag correction amount according to the current speed of the transport aircraft, and then determine the takeoff aerodynamic drag D and takeoff aerodynamic lift L of the aircraft.

15. 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 length of the transport aircraft takeoff field according to any one of claims 1 to 7.

16. 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 length of the transport aircraft take-off field according to any one of claims 1 to 7.

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