Propeller aircraft pitching moment characteristic calculation method considering dynamic influence

Abstract

The invention belongs to the field of propeller-driven aircraft pitching moment calculation, and particularly relates to a propeller-driven aircraft pitching moment characteristic calculation method considering dynamic influence. The influence of the attack angle, speed, engine tension, engine number, engine nacelle size and position, propeller diameter and rotating speed, flap deflection angle, flap chord length and wing span-chord ratio of a propeller aircraft on pitching moment is fully considered; pitching moment coefficients generated by propeller pulling force, propeller disc normal force and propeller slip flow and power influences such as horizontal empennage lower washing angle changes are accurately calculated, and then the pitching moment coefficient of the propeller-driven aircraft can be accurately obtained and used for calculating the pitching moment of the propeller-driven aircraft. Effective support can be provided for design, improvement and control of a propeller-driven aircraft.

Description

Technical Field

[0001] The present application belongs to the field of propeller aircraft pitch moment calculation, and specifically relates to a method for calculating the pitch moment characteristics of a propeller aircraft taking into account the influence of power. Background Art

[0002] Compared with jet-powered aircraft, the pitch moment characteristics of propeller aircraft are more sensitive to power influences and the calculation method is more complicated.

[0003] Dynamic effects such as propeller thrust, slipstream, normal force of the propeller disc and change in the downwash angle of the horizontal tail will cause significant changes in the pitch moment of a propeller aircraft. Currently, there is a lack of a method to calculate the pitch moment characteristics of a propeller aircraft that fully considers the dynamic effects, making it difficult to accurately derive the pitch moment of a propeller aircraft and provide effective support for the design, improvement and control of propeller aircraft.

[0004] This application is proposed in view of the above-mentioned technical defects. Summary of the invention

[0005] The purpose of the present application is to provide a method for calculating the pitch moment characteristics of a propeller aircraft taking into account the influence of power, so as to overcome or alleviate at least one aspect of the known technical defects.

[0006] The technical solution of this application is:

[0007] A method for calculating pitch moment characteristics of a propeller aircraft considering dynamic influence, comprising:

[0008] Step 1: Calculate the pitching moment coefficient △C generated by the normal force of the propeller disc mN ;

[0009] Step 2: Calculate the pitch moment coefficient △C generated by the propeller slipstream ms ;

[0010] Step 3: Calculate the pitch moment coefficient △C caused by the change in the horizontal tail downwash angle mN ;

[0011] Step 4: Calculate the pitch moment coefficient △C generated by propeller thrust mT ;

[0012] Step 5: Pitching moment coefficient △C generated by the normal force of the propeller disc mN , the pitch moment coefficient △C generated by the propeller slipstream ms , the pitch moment coefficient △C caused by the change of the horizontal tail downwash angle mN , the pitch moment coefficient △C generated by the propeller thrust mT , make corrections and obtain the pitch moment coefficient C considering the dynamic effect m-on .

[0013] According to at least one embodiment of the present application, in the above-mentioned method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power, step 1 includes:

[0014] S11. Calculate the propeller thrust coefficient related parameter β0.

[0015] S12. Calculate the pitch moment coefficient △C generated by the propeller normal force using the propeller thrust coefficient related parameter β0 mN .

[0016] According to at least one embodiment of the present application, in the above-mentioned method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power, S11 is specifically:

[0017]

[0018] in,

[0019] C T 'Propeller thrust coefficient defined for propeller thrust, speed and disc diameter;

[0020] p e is the pulling force of the engine;

[0021] ρ is the air density;

[0022] n is the propeller speed;

[0023] D is the diameter of the propeller disc;

[0024]

[0025] J is the aircraft's forward ratio;

[0026] V0 is the incoming flow velocity.

[0027] σ e =0.0003B×AF;

[0028] in,

[0029] σ e is the inherent effectiveness factor of the blade;

[0030] B is the number of blades;

[0031] AF is the active factor of the paddle;

[0032]

[0033] According to at least one embodiment of the present application, in the above-mentioned method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power, S12 is specifically:

[0034]

[0035] in,

[0036] C Nαp is the derivative of the normal force on the propeller disk with respect to the angle of attack based on the slipstream pressure and the propeller disk area;

[0037] σ e is the inherent effectiveness factor of the blade;

[0038] J is the aircraft's forward ratio;

[0039] C T 'Propeller thrust coefficient defined for propeller thrust, speed and disk diameter.

[0040] S p =πD 2 / 4;

[0041] in,

[0042] S p is the paddle disc area;

[0043] D is the diameter of the propeller disc;

[0044]

[0045] in,

[0046] C Nα is the normal force derivative of the propeller disk based on the incoming flow pressure and the wing reference area;

[0047] S ref is the wing reference area;

[0048] α p =α-θ pb ;

[0049] in,

[0050] α p is the angle of attack of the airflow relative to the propeller pull line;

[0051] α is the fuselage attack angle;

[0052] θ pb is the angle of attack of the tension line relative to the fuselage;

[0053]

[0054] in,

[0055] N is the number of engines;

[0056] x N It is the moment arm of the normal force relative to the center of gravity of the aircraft, and its direction is parallel to the line of tension;

[0057] C a is the average aerodynamic chord length.

[0058] According to at least one embodiment of the present application, in the above-mentioned method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power, step 2 includes:

[0059] S21, calculate the proportional coefficient of the pitching moment generated by the propeller slipstream

[0060] S22, proportionality coefficient of pitch moment generated by propeller slipstream Calculate the wing angle of attack related parameters α z ;

[0061] S23, calculating flap parameter φ;

[0062] S24, with the wing angle of attack related parameter α z , calculate the wing lift coefficient proportional parameters

[0063] S25. Calculate flap-related parameters using flap parameter φ

[0064] S26, wing lift coefficient proportional parameter Flap related parameters Calculate flap related parameters

[0065] According to at least one embodiment of the present application, in the above-mentioned method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power, S21 is specifically:

[0066] S p =πD 2 / 4;

[0067] in,

[0068] S p is the paddle disc area;

[0069] D is the diameter of the propeller disc;

[0070]

[0071] in,

[0072] is the lateral force derivative of the propeller disc;

[0073] C Nαp is the derivative of the normal force on the propeller disk with respect to the angle of attack based on the slipstream pressure and the propeller disk area;

[0074] J is the aircraft's forward ratio;

[0075] S p is the paddle disc area;

[0076] S ref is the wing reference area;

[0077]

[0078] in,

[0079] q0 is the incoming flow velocity pressure;

[0080] ρ is the air density;

[0081] V0 is the incoming flow velocity;

[0082]

[0083] in,

[0084] T C The aircraft drag coefficient is defined based on the aircraft drag, incoming flow pressure and wing reference area;

[0085] N is the number of engines;

[0086] p e is the pulling force of the engine;

[0087]

[0088] in,

[0089] C T is the thrust coefficient of the engine defined based on propeller thrust, slipstream pressure and propeller disc area.

[0090]

[0091] in,

[0092] V s is the slipstream velocity;

[0093]

[0094] According to at least one embodiment of the present application, in the above-mentioned method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power, S22 is specifically:

[0095] i w =θ wi +θ pb ;

[0096] in,

[0097] i w is the angle of attack of the engine pull line relative to the local wing chord line;

[0098] θ wi is the installation angle of the local wing;

[0099] θ pb is the angle of attack of the thrust axis relative to the fuselage axis;

[0100] α w =α+θ wi ;

[0101] in,

[0102] α w is the wing angle of attack;

[0103] α is the aircraft angle of attack;

[0104]

[0105] in,

[0106] α s is the angle between the slipstream velocity vector and the thrust centerline;

[0107] α p is the angle of attack of the airflow relative to the line of tension;

[0108] α0 is the zero lift angle of attack when the aircraft flaps are fully retracted and the power is off.

[0109] According to at least one embodiment of the present application, in the above-mentioned method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power, S23 is specifically:

[0110]

[0111] in,

[0112] f is the intermediate calculation parameter;

[0113] interp1 is a sequential linear interpolation function;

[0114] fsz and dtbfsz are interpolation calculation arrays;

[0115] δ t1 ,δ t2 The double-slotted Fuller-type flap deflection angle of the rear wing;

[0116] C t =fC t1 +(1-f)C t2 ;

[0117] in,

[0118] C t is the effective chord length of the two flaps of the double-slotted flap;

[0119] C t1 , C t2 is the chord length of the two flaps of the double-slotted flap;

[0120]

[0121] in,

[0122] E is the relative chord length of the engine installation position;

[0123] C is the chord length of the wing at the engine installation position;

[0124] C' is the chord length of the wing with the flaps extended;

[0125] φ=an cos(2E-1);

[0126] in,

[0127] ancos is the inverse cosine function.

[0128] According to at least one embodiment of the present application, in the above-mentioned method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power, S24 is specifically:

[0129]

[0130] in,

[0131] C Lth (α z ,0) is the angle of attack of the wing corresponding to α based on the thin wing theory z The lift coefficient of

[0132] C Lth (α z ,δ) is based on the thin wing theory, the flap deflection δ, the angle of attack corresponds to α z The lift coefficient.

[0133] According to at least one embodiment of the present application, in the above-mentioned method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power, S25 is specifically:

[0134]

[0135] According to at least one embodiment of the present application, in the above-mentioned method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power, S26 is specifically:

[0136]

[0137] in,

[0138] x s is the chordwise distance from the slipstream pressure center to the local wing leading edge point;

[0139]

[0140] C Ls is the lift coefficient increment produced by propeller slipstream;

[0141] △x le is the chordwise distance from the leading edge of the wing to the leading edge of the mean aerodynamic chord;

[0142] x cg is the chordwise position of the aircraft's center of gravity relative to the leading edge of the mean aerodynamic chord;

[0143] C a is the average aerodynamic chord length of the wing;

[0144] α w is the wing angle of attack.

[0145] According to at least one embodiment of the present application, in the above-mentioned method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power, step three includes:

[0146] S31. Calculate the downwash angle ε of the horizontal tail under the aircraft pull coefficient defined based on the aircraft pull, incoming flow pressure and wing reference area s ;

[0147] S32, calculating the downwash angle ε0 of the horizontal tail in the unpowered state;

[0148] S33, to calculate the downwash angle ε of the horizontal tail under the aircraft pull coefficient defined based on the aircraft pull, the incoming flow pressure and the wing reference area s , and the downwash angle ε0 of the horizontal tail in the unpowered state, calculate the lift coefficient change △C caused by the downwash change of the horizontal tail Lht ;

[0149] S34, the lift coefficient change △C caused by the horizontal tail downwash change Lht , calculate the pitch moment coefficient △C caused by the change of the horizontal tail downwash angle mN .

[0150] According to at least one embodiment of the present application, in the above-mentioned method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power, S31 is specifically:

[0151]

[0152] in,

[0153] C Lwon is the lift coefficient of the wing + flap system under the aircraft pull coefficient defined based on the aircraft pull, incoming flow pressure and wing reference area;

[0154] T C The aircraft drag coefficient is defined based on the aircraft drag, incoming flow pressure and wing reference area;

[0155] α p is the angle of attack of the airflow relative to the line of tension;

[0156] AR is the aspect ratio of the wing.

[0157] According to at least one embodiment of the present application, in the above-mentioned method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power, S32 is specifically:

[0158]

[0159] in,

[0160] C Lwoff is the lift coefficient of the wing + flap system in the unpowered state.

[0161] According to at least one embodiment of the present application, in the above-mentioned method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power, S33 is specifically:

[0162]

[0163] in,

[0164] C Lαht is the lift line slope of the horizontal tail in natural flow;

[0165] k q is the airflow resistance factor of the horizontal tail;

[0166] S ht is the horizontal tail area;

[0167] S ref is the reference area of ​​the wing.

[0168] According to at least one embodiment of the present application, in the above-mentioned method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power, S34 is specifically:

[0169]

[0170] in,

[0171] x ht is the distance in the airflow direction from the pressure center of the horizontal tail to the leading edge of the mean aerodynamic chord;

[0172] x cg is the chordwise position of the aircraft's center of gravity relative to the leading edge of the mean aerodynamic chord;

[0173] C ais the average aerodynamic chord length of the wing.

[0174] According to at least one embodiment of the present application, in the above-mentioned method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power, step 4 is specifically as follows:

[0175]

[0176] in,

[0177] T C The aircraft drag coefficient is defined based on the aircraft drag, incoming flow pressure and wing reference area;

[0178] z p-cg It is the height of the propeller disc center of gravity from the aircraft center of gravity, and its direction is perpendicular to the fuselage axis;

[0179] θ pb is the angle of attack of the thrust axis relative to the fuselage axis;

[0180] C a is the average aerodynamic chord length of the wing.

[0181] According to at least one embodiment of the present application, in the above-mentioned method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power, step five includes:

[0182] S51. Calculate the pitching moment coefficient △C generated by the normal force of the propeller disc mN , the pitch moment coefficient △C generated by the propeller slipstream ms , the pitch moment coefficient △C caused by the change of the horizontal tail downwash angle mN , the pitch moment coefficient △C generated by the propeller thrust mT Correction influence △C m-on ;

[0183] S52, Pitching moment coefficient △C generated by the normal force of the propeller disc mN , the pitch moment coefficient △C generated by the propeller slipstream ms , the pitch moment coefficient △C caused by the change of the horizontal tail downwash angle mN , the pitch moment coefficient △C generated by the propeller thrust mT Correction influence △C m-on , make corrections and obtain the pitch moment coefficient C considering the dynamic effect m-on .

[0184] According to at least one embodiment of the present application, in the above-mentioned method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power, S51 is specifically:

[0185] △C m-on =△C mN +△C ms+△C mht +△C mT .

[0186] According to at least one embodiment of the present application, in the above-mentioned method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power, S52 is specifically:

[0187] C m-on =C m-off +△C m-on ;

[0188] in,

[0189] C m-off is the pitch moment coefficient of the aircraft in the unpowered state.

[0190] This application has at least the following beneficial technical effects:

[0191] The invention provides a method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of dynamic force, fully considering the influence of the propeller aircraft angle of attack, speed, engine thrust, number of engines, engine nacelle size and position, propeller diameter and rotation speed, flap deflection angle, flap chord length, and wing aspect ratio on the pitch moment, accurately calculating the pitch moment coefficient generated by dynamic forces such as propeller thrust, propeller disc normal force, propeller slipstream generation, and horizontal tail downwash angle change, and thus being able to accurately obtain the pitch moment coefficient of the propeller aircraft for use in the pitch moment calculation of the propeller aircraft, which can provide effective support for the design, improvement, and control of the propeller aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0192] Figure 1 It is a schematic diagram of a method for calculating the pitch moment characteristics of a propeller aircraft taking into account the influence of power provided in an embodiment of the present application.

[0193] In order to better illustrate the present embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. In addition, the drawings are only used for illustrative purposes and should not be construed as limitations on the present application. DETAILED DESCRIPTION

[0194] In order to make the technical solution and advantages of the present application clearer, the technical solution of the present application will be described in further detail in detail and in detail with reference to the accompanying drawings. It can be understood that the specific embodiments described here are only partial embodiments of the present application, which are only used to explain the present application, not to limit the present application. It should be noted that, for the convenience of description, only the parts related to the present application are shown in the accompanying drawings, and other related parts can refer to the general design.

[0195] In addition, unless otherwise defined, the technical terms or scientific terms used in the description of this application shall have the usual meanings understood by those of ordinary skill in the art to which this application belongs. The words used in the description of this application to indicate orientation are only used to indicate relative directions or positional relationships. When the absolute position of the described object changes, its relative positional relationship may also change accordingly. The word "include" used in the description of this application indicates that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, but does not exclude other elements or objects.

[0196] In addition, it should be noted that, unless otherwise clearly specified and limited, the words "installation", "connection" and similar terms used in the description of this application should be understood in a broad sense. For example, the connection can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Technical personnel in the field can understand its specific meaning in this application according to the specific circumstances.

[0197] The pitch moment dynamic influence correction of a propeller aircraft mainly consists of four parts: the pitch moment generated by the normal force of the propeller disc, the pitch moment generated by the propeller slipstream, the pitch moment generated by the change of the horizontal tail downwash angle, and the pitch moment generated by the propeller pull. Based on this, the present application provides a method for calculating the pitch moment characteristics of a propeller aircraft considering the dynamic influence, such as Figure 1 shown.

[0198] Step 1: Calculate the pitching moment coefficient △C generated by the normal force of the propeller disc mN .

[0199] S11. Calculate the propeller thrust coefficient related parameter β0.

[0200]

[0201] in,

[0202] C' T Propeller thrust coefficient defined for propeller thrust, speed and disc diameter;

[0203] p e is the pulling force of the engine;

[0204] ρ is the air density;

[0205] n is the propeller speed;

[0206] D is the propeller disc diameter.

[0207]

[0208] J is the aircraft's forward ratio;

[0209] V0 is the incoming flow velocity.

[0210] σ e =0.0003B×AF……1-3

[0211] in,

[0212] σ e is the inherent effectiveness factor of the blade;

[0213] B is the number of blades;

[0214] AF is the active factor of the blade.

[0215]

[0216] And there are:

[0217]

[0218]

[0219]

[0220]

[0221] S p =πD 2 / 4;

[0222] in,

[0223] C T is the thrust coefficient of the engine defined based on propeller thrust, slipstream pressure and propeller disc area;

[0224] q s is the slip velocity pressure;

[0225] S p is the paddle disc area;

[0226] S ref is the wing reference area;

[0227] N is the number of engines;

[0228] T C The aircraft drag coefficient is defined based on the aircraft drag, incoming flow pressure and wing reference area;

[0229] q0 is the incoming flow velocity pressure;

[0230] S ref is the reference area of ​​the wing.

[0231] To solve the propeller thrust coefficient related parameter β0, we can first calculate the propeller thrust coefficient C' defined by the propeller thrust, speed and propeller disk diameter. T , then discretize the parameter β0 between [0,90], construct the β0 array, and use the interpolation algorithm to solve the numerical solution of β0.

[0232] S12. Calculate the pitch moment coefficient △C generated by the propeller normal force using the propeller thrust coefficient related parameter β0 mN .

[0233]

[0234] in,

[0235] C Nαp is the derivative of the normal force on the propeller disk with respect to the angle of attack based on the slipstream pressure and the propeller disk area;

[0236] σ e is the inherent effectiveness factor of the blade;

[0237] J is the aircraft's forward ratio;

[0238] C T 'Propeller thrust coefficient defined for propeller thrust, speed and disk diameter.

[0239] S p =πD 2 / 4……2-2

[0240] in,

[0241] S p is the paddle disc area;

[0242] D is the propeller disc diameter.

[0243]

[0244] in,

[0245] C Nα is the normal force derivative of the propeller disk based on the incoming flow pressure and the wing reference area;

[0246] S ref is the reference area of ​​the wing.

[0247] α p =α-θ pb …2-4

[0248] in,

[0249] α p is the angle of attack of the airflow relative to the propeller pull line;

[0250] α is the fuselage attack angle;

[0251] θ pb is the angle of attack of the tension line relative to the fuselage.

[0252]

[0253] in,

[0254] N is the number of engines;

[0255] x N It is the moment arm of the normal force relative to the center of gravity of the aircraft, and its direction is parallel to the line of tension;

[0256] C a is the average aerodynamic chord length.

[0257] Step 2: Calculate the pitch moment coefficient △C generated by the propeller slipstream ms .

[0258] S21, calculate the proportional coefficient of the pitching moment generated by the propeller slipstream

[0259] S p =πD 2 / 4……3-1

[0260] in,

[0261] S p is the paddle disc area;

[0262] D is the propeller disc diameter.

[0263]

[0264] in,

[0265] is the lateral force derivative of the propeller disc;

[0266] C Nαp is the derivative of the normal force on the propeller disk with respect to the angle of attack based on the slipstream pressure and the propeller disk area;

[0267] J is the aircraft's forward ratio;

[0268] S p is the paddle disc area;

[0269] S ref is the reference area of ​​the wing.

[0270]

[0271] in,

[0272] q0 is the incoming flow velocity pressure;

[0273] ρ is the air density;

[0274] V0 is the incoming flow velocity.

[0275]

[0276] in,

[0277] T C The aircraft drag coefficient is defined based on the aircraft drag, incoming flow pressure and wing reference area;

[0278] N is the number of engines;

[0279] p e The pulling force of the engine.

[0280]

[0281] in,

[0282] C T is the thrust coefficient of the engine defined based on propeller thrust, slipstream pressure and propeller disc area.

[0283]

[0284] in,

[0285] V s is the slipstream velocity.

[0286]

[0287] S22, proportionality coefficient of pitch moment generated by propeller slipstream Calculate the wing angle of attack related parameters α z .

[0288] i w =θ wi +θ pb …4-1

[0289] in,

[0290] i w is the angle of attack of the engine pull line relative to the local wing chord line;

[0291] θ wi is the installation angle of the local wing;

[0292] θ pb It is the angle of attack of the thrust axis relative to the fuselage axis.

[0293] α w =α+θ wi …4-2

[0294] in,

[0295] α w is the wing angle of attack;

[0296] α is the aircraft angle of attack.

[0297]

[0298] in,

[0299] α s is the angle between the slipstream velocity vector and the thrust centerline;

[0300] α p is the angle of attack of the airflow relative to the line of tension;

[0301] α0 is the zero lift angle of attack when the aircraft flaps are fully retracted and the power is off.

[0302] S23. Calculate flap parameter φ.

[0303]

[0304] in,

[0305] f is the intermediate calculation parameter;

[0306] interp1 is a sequential linear interpolation function;

[0307] fsz and dtbfsz are interpolation calculation arrays;

[0308] δ t1 ,δ t2 The deflection angle of the double-slotted Fuller flap on the rear wing.

[0309] fsz and dtbfsz are interpolation calculation arrays, which can be referred to as follows: dtbfsz 0 0.2 0.4 0.6 0.8 1 plant 0 0.16 0.34 0.55 0.76 1

[0310] C t =fC t1 +(1-f)C t2 ……5-2

[0311] in,

[0312] C t is the effective chord length of the two flaps of the double-slotted flap;

[0313] C t1 , C t2 is the chord length of the two flaps of the double-slotted flap.

[0314]

[0315] in,

[0316] E is the relative chord length of the engine installation position;

[0317] C is the chord length of the wing at the engine installation position;

[0318] C' is the chord length of the wing with the flaps extended.

[0319] φ=an cos(2E-1)……5-4

[0320] in,

[0321] ancos is the inverse cosine function.

[0322] S24, with the wing angle of attack related parameter α z , calculate the wing lift coefficient proportional parameters

[0323]

[0324] in,

[0325] C Lth (α z ,0) is the angle of attack of the wing corresponding to α based on the thin wing theory z The lift coefficient of

[0326] C Lth (α z ,δ) is based on the thin wing theory, the flap deflection δ, the angle of attack corresponds to α z The lift coefficient.

[0327] S25. Calculate flap-related parameters using flap parameter φ

[0328]

[0329] S26, wing lift coefficient proportional parameter Flap related parameters Calculate the pitch moment coefficient △C generated by propeller slipstream ms .

[0330]

[0331] in,

[0332] x s is the chordwise distance from the slipstream pressure center to the local wing leading edge point.

[0333]

[0334] C Ls is the lift coefficient increment produced by propeller slipstream;

[0335] △xle is the chordwise distance from the leading edge of the wing to the leading edge of the mean aerodynamic chord;

[0336] x cg is the chordwise position of the aircraft's center of gravity relative to the leading edge of the mean aerodynamic chord;

[0337] C a is the average aerodynamic chord length of the wing;

[0338] α w is the wing angle of attack.

[0339] Step 3: Calculate the pitch moment coefficient △C caused by the change in the horizontal tail downwash angle mN .

[0340] S31. Calculate the downwash angle ε of the horizontal tail under the aircraft pull coefficient defined based on the aircraft pull, incoming flow pressure and wing reference area s .

[0341]

[0342] in,

[0343] C Lwon is the lift coefficient of the wing + flap system under the aircraft pull coefficient defined based on the aircraft pull, incoming flow pressure and wing reference area;

[0344] T C The aircraft drag coefficient is defined based on the aircraft drag, incoming flow pressure and wing reference area;

[0345] α p is the angle of attack of the airflow relative to the line of tension;

[0346] AR is the aspect ratio of the wing.

[0347] S32. Calculate the downwash angle ε0 of the horizontal tail in the unpowered state.

[0348]

[0349] in,

[0350] C Lwoff is the lift coefficient of the wing + flap system in the unpowered state.

[0351] S33, to calculate the downwash angle ε of the horizontal tail under the aircraft pull coefficient defined based on the aircraft pull, the incoming flow pressure and the wing reference area s , and the downwash angle ε0 of the horizontal tail in the unpowered state, calculate the lift coefficient change △C caused by the downwash change of the horizontal tail Lht .

[0352]

[0353] in,

[0354] C Lαht is the lift line slope of the horizontal tail in natural flow;

[0355] k q is the airflow resistance factor of the horizontal tail;

[0356] S ht is the horizontal tail area;

[0357] S ref is the reference area of ​​the wing.

[0358] S34, the lift coefficient change △C caused by the horizontal tail downwash change Lht , calculate the pitch moment coefficient △C caused by the change of the horizontal tail downwash angle mN .

[0359]

[0360] in,

[0361] x ht is the distance in the airflow direction from the pressure center of the horizontal tail to the leading edge of the mean aerodynamic chord;

[0362] x cg is the chordwise position of the aircraft's center of gravity relative to the leading edge of the mean aerodynamic chord;

[0363] C a is the average aerodynamic chord length of the wing.

[0364] Step 4: Calculate the pitch moment coefficient △C generated by propeller thrust mT .

[0365]

[0366] in,

[0367] T C The aircraft drag coefficient is defined based on the aircraft drag, incoming flow pressure and wing reference area;

[0368] z p-cg It is the height of the propeller disc center of gravity from the aircraft center of gravity, and its direction is perpendicular to the fuselage axis;

[0369] θ pb is the angle of attack of the thrust axis relative to the fuselage axis;

[0370] C a is the average aerodynamic chord length of the wing.

[0371] Step 5: Pitching moment coefficient △C generated by the normal force of the propeller disc mN , the pitch moment coefficient △C generated by the propeller slipstream ms , the pitch moment coefficient △C caused by the change of the horizontal tail downwash angle mN , the pitch moment coefficient △C generated by the propeller thrust mT , make corrections and obtain the pitch moment coefficient C considering the dynamic effect m-on .

[0372] S51. Calculate the pitching moment coefficient △C generated by the normal force of the propeller disc mN , the pitch moment coefficient △C generated by the propeller slipstream ms , the pitch moment coefficient △C caused by the change of the horizontal tail downwash angle mN , the pitch moment coefficient △C generated by the propeller thrust mT Correction influence △C m-on .

[0373] △C m-on =△C mN +△C ms +△C mht +△C mT ……11-1

[0374] S52, Pitching moment coefficient △C generated by the normal force of the propeller disc mN , the pitch moment coefficient △C generated by the propeller slipstream ms , the pitch moment coefficient △C caused by the change of the horizontal tail downwash angle mN , the pitch moment coefficient △C generated by the propeller thrust mT Correction influence △C m-on , make corrections and obtain the pitch moment coefficient C considering the dynamic effect m-on .

[0375] C m-on =C m-off +△C m-on ……11-2

[0376] in,

[0377] C m-off is the pitch moment coefficient of the aircraft in the unpowered state.

[0378] In a specific embodiment, the propeller aircraft has a wing area of ​​65m2, a wingspan of 26.2m, an aspect ratio of 10.56, and an average aerodynamic chord length of 2.5m. Two turboprop engines are suspended under the wing, with a propeller disk diameter of 4.4m, a number of blades of 6, and a blade parameter AF of 188. The local wing chord length is 2.6m, the thrust axis has an angle of attack of 1° relative to the fuselage axis, and the local wing installation angle is 3°. Takeoff configuration: the trailing edge double-slotted Fuller flap has a deflection angle of 20°+8°, the relative chord length of the two flaps is 0.2+0.1, and the chord length of the wing after the flaps are released is 1.2 times the original chord length. The pitch moment corresponding to the unpowered state angle of attack of 13.5° is -0.62, the lift coefficient of the wing + flap system is 2.18, and the zero lift angle of attack of the unpowered state flap retracted configuration is -2°. The center of the propeller disk is 0.28m higher than the center of gravity of the aircraft, the distance of the normal force of the disk relative to the center of gravity in the direction of the pulling force line is 2.35m, the distance of the pressure center of the horizontal tail from the leading edge of the mean aerodynamic chord in the direction of the airflow is 12.3m, the leading edge of the wing at the engine installation position is at the same position as the leading edge of the mean aerodynamic chord, and the center of gravity of the aircraft is located at 25% of the mean aerodynamic chord. The incoming flow velocity is 75m / s, the engine speed is 23.6 rpm, the corresponding engine thrust is 33.56KN, and the lift coefficient increment generated by the slipstream is 0.656. The aircraft angle of attack is 13.5°, then the method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power disclosed in the above embodiment, calculates the pitch moment, and is specifically implemented as follows:

[0379] The calculation process of the pitching moment considering the dynamic effect is as follows:

[0380] 1) Calculate β0, as shown in Table 1:

[0381] 2) Calculate △C mN , as shown in Table 2:

[0382] 3) Calculation As shown in Table 3:

[0383] 4) Calculate α z , as shown in Table 4:

[0384] 5) Calculate φ, as shown in Table 5:

[0385] 6) Calculation As shown in Table 6:

[0386] 7) Calculation As shown in Table 7:

[0387] 8) Calculate x s , as shown in Table 8:

[0388] 10) Calculate △C ms , as shown in Table 9:

[0389] 11) Calculate △C mht , as shown in Table 10:

[0390] 12) Calculate △C mT and C m-on , as shown in Table 11:

[0391] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the scope of protection of the present application.

Claims

1. A method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power, characterized in that: include: Step 1: Calculate the pitching moment coefficient △C generated by the normal force of the propeller disc mN ; Step 2: Calculate the pitch moment coefficient △C generated by the propeller slipstream ms ; Step 3: Calculate the pitch moment coefficient △C caused by the change in the horizontal tail downwash angle mN ; Step 4: Calculate the pitch moment coefficient △C generated by propeller thrust mT ; Step 5: Pitching moment coefficient △C generated by the normal force of the propeller disc mN , the pitch moment coefficient △C generated by the propeller slipstream ms , the pitch moment coefficient △C caused by the change of the horizontal tail downwash angle mN , the pitch moment coefficient △C generated by the propeller thrust mT , make corrections and obtain the pitch moment coefficient C considering the dynamic effect m-on .

2. The method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power according to claim 1, characterized in that: Step one includes: S11. Calculate the propeller thrust coefficient related parameter β0. S12. Calculate the pitch moment coefficient △C generated by the propeller normal force using the propeller thrust coefficient related parameter β0 mN .

3. The method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power according to claim 2, characterized in that: S11 is as follows: in, C' T Propeller thrust coefficient defined for propeller thrust, speed and disc diameter; p e is the pulling force of the engine; ρ is the air density; n is the propeller speed; D is the diameter of the propeller disc; J is the aircraft's forward ratio; V0 is the incoming flow velocity. s e =0.0003B×AF; in, σ e is the inherent effectiveness factor of the blade; B is the number of blades; AF is the active factor of the paddle; 4. The method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power according to claim 1, characterized in that: S12 is specifically: in, C Nαp is the derivative of the normal force on the propeller disk with respect to the angle of attack based on the slipstream pressure and the propeller disk area; σ e is the inherent effectiveness factor of the blade; J is the aircraft's forward ratio; C' T Propeller thrust coefficient defined for propeller thrust, speed, and disk diameter. S p =πD 2 / 4; in, S p is the paddle disc area; D is the propeller disc diameter; in, C Nα is the normal force derivative of the propeller disk based on the incoming flow pressure and the wing reference area; S ref is the wing reference area; a p =α-θ pb ; in, α p is the angle of attack of the airflow relative to the propeller pull line; α is the fuselage attack angle; θ pb is the angle of attack of the tension line relative to the fuselage; in, N is the number of engines; x N It is the moment arm of the normal force relative to the center of gravity of the aircraft, and its direction is parallel to the line of tension; C a is the average aerodynamic chord length.

5. The method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power according to claim 4, characterized in that: Step 2 includes: S21, calculate the proportional coefficient of the pitching moment generated by the propeller slipstream S22, proportionality coefficient of pitch moment generated by propeller slipstream Calculate the wing angle of attack related parameters α z ; S23, calculating flap parameter φ; S24, with the wing angle of attack related parameter α z , calculate the wing lift coefficient proportional parameters S25. Calculate flap-related parameters using flap parameter φ S26, wing lift coefficient proportional parameter Flap related parameters Calculate flap related parameters 6. The method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power according to claim 5, characterized in that: S21 is specifically: S p =πD 2 / 4; in, S p is the paddle disc area; D is the diameter of the propeller disc; in, is the lateral force derivative of the propeller disc; C Nαp is the derivative of the normal force on the propeller disk with respect to the angle of attack based on the slipstream pressure and the propeller disk area; J is the aircraft's forward ratio; S p is the paddle disc area; S ref is the wing reference area; q0=0.5ρV0 2 ; in, q0 is the incoming flow velocity pressure; ρ is the air density; V0 is the incoming flow velocity; in, T C The aircraft drag coefficient is defined based on the aircraft drag, incoming flow pressure and wing reference area; N is the number of engines; p e is the pulling force of the engine; in, C T is the thrust coefficient of the engine defined based on propeller thrust, slipstream pressure and propeller disc area. in, V s is the slipstream velocity; 7. The method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power according to claim 6, characterized in that: S22 is specifically: I w =θ wi +θ pb ; in, i w is the angle of attack of the engine pull line relative to the local wing chord line; θ wi is the installation angle of the local wing; θ pb is the angle of attack of the thrust axis relative to the fuselage axis; a w =α+θ wi ; in, α w is the wing angle of attack; α is the aircraft angle of attack; in, α s is the angle between the slipstream velocity vector and the thrust centerline; α p is the angle of attack of the airflow relative to the line of force; α0 is the zero lift angle of attack when the aircraft flaps are fully retracted and the power is off.

8. The method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power according to claim 7, characterized in that: S23 is specifically: in, f is the intermediate calculation parameter; interp1 is a sequential linear interpolation function; fsz and dtbfsz are interpolation calculation arrays; δ t1 , δ t2 The double-slotted Fuller-type flap deflection angle of the rear wing; C t =fC t1 +(1-f)C t2 ; in, C t is the effective chord length of the two flaps of the double-slotted flap; C t1 , C t2 is the chord length of the two flaps of the double-slotted flap; in, E is the relative chord length of the engine installation position; C is the chord length of the wing at the engine installation position; C' is the chord length of the wing with the flaps extended; φ=an cos(2E-1); in, an cos is the inverse cosine function.

9. The method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power according to claim 8, characterized in that: S24 is specifically: in, C Lth (α z ,0) is the angle of attack of the wing corresponding to α based on the thin wing theory z The lift coefficient of C Lth (α z ,δ) is based on the thin wing theory, the flap deflection δ, the angle of attack corresponds to α z The lift coefficient.

10. The method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power according to claim 9, characterized in that: S25 is specifically:

11. The method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power according to claim 10, characterized in that: S26 is specifically: in, x s is the chordwise distance from the slipstream pressure center to the local wing leading edge point; C Ls is the lift coefficient increment produced by propeller slipstream; △x le is the chordwise distance from the leading edge of the wing to the leading edge of the mean aerodynamic chord; x cg is the chordwise position of the aircraft's center of gravity relative to the leading edge of the mean aerodynamic chord; C a is the average aerodynamic chord length of the wing; α w is the wing angle of attack.

12. The method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power according to claim 11, characterized in that: Step three includes: S31. Calculate the downwash angle ε of the horizontal tail under the aircraft pull coefficient defined based on the aircraft pull, incoming flow pressure and wing reference area s ; S32, calculating the downwash angle ε0 of the horizontal tail in the unpowered state; S33, to calculate the downwash angle ε of the horizontal tail under the aircraft pull coefficient defined based on the aircraft pull, the incoming flow pressure and the wing reference area s , and the downwash angle ε0 of the horizontal tail in the unpowered state, calculate the lift coefficient change △C caused by the downwash change of the horizontal tail Lht ; S34, the lift coefficient change △C caused by the horizontal tail downwash change Lht , calculate the pitch moment coefficient △C caused by the change of the horizontal tail downwash angle mN .

13. The method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power according to claim 12, characterized in that: S31 is specifically: in, C Lwon is the lift coefficient of the wing + flap system under the aircraft pull coefficient defined based on the aircraft pull, incoming flow pressure and wing reference area; T C The aircraft drag coefficient is defined based on the aircraft drag, incoming flow pressure and wing reference area; α p is the angle of attack of the airflow relative to the line of force; AR is the aspect ratio of the wing.

14. The method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power according to claim 13, characterized in that: S32 is specifically: in, C Lwoff is the lift coefficient of the wing + flap system in the unpowered state.

15. The method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power according to claim 14, characterized in that: S33 is specifically: in, C Lαht is the lift line slope of the horizontal tail in natural flow; k q is the airflow resistance factor of the horizontal tail; S ht is the horizontal tail area; S ref is the reference area of ​​the wing.

16. The method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power according to claim 15, characterized in that: S34 is specifically: in, x ht is the distance in the airflow direction from the pressure center of the horizontal tail to the leading edge of the mean aerodynamic chord; x cg is the chordwise position of the aircraft's center of gravity relative to the leading edge of the mean aerodynamic chord; C a is the average aerodynamic chord length of the wing.

17. The method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power according to claim 16, characterized in that: Step 4 is as follows: in, T C The aircraft drag coefficient is defined based on the aircraft drag, incoming flow pressure and wing reference area; z p-cg It is the height of the propeller disc center of gravity from the aircraft center of gravity, and its direction is perpendicular to the fuselage axis; θ pb is the angle of attack of the thrust axis relative to the fuselage axis; C a is the average aerodynamic chord length of the wing.

18. The method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power according to claim 17, characterized in that: Step five includes: S51. Calculate the pitching moment coefficient △C generated by the normal force of the propeller disc mN , the pitch moment coefficient △C generated by the propeller slipstream ms , the pitch moment coefficient △C caused by the change of the horizontal tail downwash angle mN , the pitch moment coefficient △C generated by the propeller thrust mT Correction influence △C m-on ; S52, Pitching moment coefficient △C generated by the normal force of the propeller disc mN , the pitch moment coefficient △C generated by the propeller slipstream ms , the pitch moment coefficient △C caused by the change of the horizontal tail downwash angle mN , the pitch moment coefficient △C generated by the propeller thrust mT Correction influence △C m-on , make corrections and obtain the pitch moment coefficient C considering the dynamic effect m-on .

19. The method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power according to claim 18, characterized in that: S51 is specifically: △C m-on =△C mN +△C ms +△C mht +△C mT 。 20. The method for calculating the pitch moment characteristics of a propeller aircraft considering the influence of power according to claim 19, characterized in that: S52 is specifically: C m-on =C m-off +△C m-on ; in, C m-off is the pitch moment coefficient of the aircraft in the unpowered state.

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