Method for calculating air-slip performance of fixed-wing turboprop aircraft

Abstract

The invention belongs to the field of flight performance design, and relates to a method for calculating the air-slip performance of a fixed-wing turboprop aircraft. The method comprises the steps that according to the characteristics of a turbine engine and a propeller, the combined characteristics of a propeller aircraft power device are determined, the influence of feathering of the propeller on the aerodynamic characteristics of an aircraft is considered, and the needed aircraft air-slip performance is obtained through modeling and adjustment calculation according to aerodynamic characteristic parameters and weight characteristic parameters of the aircraft.

Description

Technical Field

[0001] The invention belongs to the field of flight performance design and relates to a method for calculating the air-gliding performance of a fixed-wing turboprop aircraft. Background Art

[0002] Turboprop aircraft are generally used for transporting and delivering cargo, equipment, and personnel. Considering range and flight time requirements, airfoils with relatively large aspect ratios are generally selected. Airfoils with large aspect ratios inherently possess excellent gliding characteristics. If all engines fail during flight, the aircraft and pilot would be in extreme danger. Aircraft with good gliding capabilities offer a certain degree of safety during power failure. By determining the aircraft's altitude, speed, weight, attitude, and other parameters when it enters gliding mode, the aircraft's gliding capability can be calculated based on the aircraft's aerodynamic parameters. Clearly understanding the aircraft's gliding performance can help pilots correctly and accurately control the aircraft if it loses all power, allowing them to restart the engines mid-air or make an emergency landing in a favorable attitude. This performance, in turn, largely determines the safety of both the flight crew and the aircraft.

[0003] The current common method for calculating the air-gliding performance of turboprop aircraft generally only considers the air-gliding characteristics brought by the airfoil, ignoring the analysis of actual conditions such as the engine feathering resistance and the fuselage induced drag factor. As a result, the air-gliding performance data of turboprop aircraft obtained in this way have large deviations. Summary of the Invention

[0004] Purpose of the invention: To provide a method for calculating the air-gliding performance of a turboprop aircraft, so as to solve the problem that the current air-gliding performance calculation of a turboprop aircraft has a large deviation from the actual air-gliding capability of the aircraft, and to greatly improve the accuracy of the air-gliding performance calculation.

[0005] Technical solution:

[0006] A method for calculating the air-gliding performance of a fixed-wing turboprop aircraft is provided, comprising:

[0007] Based on the characteristics of the turbine engine and propeller, the combined characteristics of the propeller aircraft power unit are determined, and the influence of propeller feathering on the aircraft aerodynamic characteristics is considered. According to the aircraft aerodynamic characteristic parameters and weight characteristic parameters, the required aircraft air-gliding performance is obtained through modeling and adjustment calculations.

[0008] Furthermore, based on the characteristics of the turbine engine and propeller, the combined characteristics of the propeller aircraft power plant are determined, and the impact of propeller feathering on the aircraft's aerodynamic characteristics is considered. Based on the aircraft's aerodynamic and weight characteristic parameters, the required aircraft air-gliding performance is obtained through modeling, adjustment, and calculation, including:

[0009] The first step is to obtain the air-slip related parameters of the turboprop aircraft; the air-slip related parameters include: basic parameters, environmental parameters, flight parameters and aerodynamic characteristic parameters;

[0010] The second step is to determine the aircraft's lift coefficient C based on the aircraft's basic parameters, flight parameters, and aerodynamic characteristics. L and the drag coefficient C D ;

[0011] The third step is to analyze the air-gliding forces of the turboprop aircraft, taking into account the environmental parameters and the flight state at the moment of engine shutdown: the lift coefficient and drag coefficient are used to determine the lift-to-drag ratio K, the fuselage angle of attack α, the lift L, the aerodynamic drag Q, and the total drag Q during the air-gliding period. 总 ;

[0012] In the fourth step, the parameters of the first to third steps are introduced into the fixed-wing turboprop aircraft air-gliding model to determine the air-gliding performance of the turboprop aircraft.

[0013] Furthermore, the basic parameters include: the weight M of the turboprop aircraft, the fuselage area S, and the feathering resistance F of the aircraft's single engine blade; the environmental parameters include: the aircraft's starting altitude H, air density ρ, and speed of sound V1; the flight parameters include: the aircraft's starting speed V for air sliding t , Mach number M a , speed pressure q; aerodynamic characteristic parameters are obtained from wind tunnel tests, including the lift line slope C under different aircraft attitudes and Mach numbers Lα , zero lift angle of attack α0, minimum drag coefficient C Dmin , induced drag factor A, set drag coefficient C LDM .

[0014] Furthermore, the aircraft's lift coefficient C L and the drag coefficient C D The calculation formula is:

[0015]

[0016] C D =C Dmin +A*(C L -C LDM ) 2 ;

[0017] M—aircraft mass; S—fuselage area; ρ—air density; V t —The speed at which the aircraft starts to glide; C LDM —Set resistance coefficient; C L —lift coefficient; C Dmin —minimum drag coefficient; A—induced drag factor; g—acceleration due to gravity.

[0018] Furthermore, when the aircraft is gliding, the lift-to-drag ratio K, the fuselage angle of attack αα, the lift L, the aerodynamic drag Q and the total drag Q 总 The calculation formula is:

[0019]

[0020] L=C L *q*S;

[0021] Q=C D *q*S;

[0022] Q 总 =Q+4*F;

[0023] C D -drag coefficient; F-feathering resistance of a single engine blade; q-speed pressure; α0-zero lift angle of attack.

[0024] Furthermore, the turboprop aircraft glide performance includes: aircraft glide angle γ, glide ratio b, glide horizontal distance J and glide time t.

[0025] Furthermore, the calculation formulas for the aircraft's air-gliding gliding angle γ, air-gliding ratio b, air-gliding horizontal distance J, and air-gliding time t are as follows:

[0026]

[0027] JH*b;

[0028]

[0029] Beneficial effects:

[0030] The present invention determines the lift coefficient C of the turboprop aircraft by first determining the physical parameters, environmental parameters and aerodynamic characteristic parameters of the turboprop aircraft and combining the effect of the propeller feathering on the aerodynamic characteristics of the aircraft. L and the drag coefficient C D , and then determine the lift-to-drag ratio K, fuselage angle of attack αα, lift L, aerodynamic drag Q and total drag Q when the aircraft is gliding through force analysis 总 Finally, the aircraft's air-gliding descent angle γ, air-gliding ratio b, air-gliding horizontal distance J and air-gliding time t are calculated.

[0031] This calculation method is intuitive, simple, and has clear theoretical logic, making it easy for aircraft designers to master. This method is comprehensive, versatile, and has broad application value, suitable for medium and large turboprop passenger aircraft, transport aircraft, and related platform aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a flowchart for calculating the air-gliding performance of a turboprop aircraft.

[0033] Figure 2 This is a force analysis diagram for a turboprop aircraft during air taxiing. DETAILED DESCRIPTION

[0034] Combine Figure 1 , provides a method for calculating the air-gliding performance of a turboprop aircraft, the method comprising the following steps:

[0035] Step 1: Determine the parameters related to the air sliding of the turboprop aircraft, including the basic parameters such as the weight M of the turboprop aircraft, the fuselage area S, the blade feathering resistance F of the aircraft's single engine, the environmental parameters such as the aircraft's air sliding starting altitude H, air density ρ, speed of sound V1, and the aircraft's air sliding starting speed V. t , Mach number Ma, speed pressure q and other flight parameters, and refer to the lift line slope C under different aircraft attitudes and Mach numbers obtained through wind tunnel tests Lα , zero lift angle of attack α0, minimum drag coefficient C Dmin , induced drag factor A, set drag coefficient C LDM Aerodynamic characteristic parameters such as

[0036] Step 2: Determine the effect of propeller feathering on the aircraft's aerodynamic characteristics: Based on the aircraft's basic parameters, flight parameters, and aerodynamic characteristics, the aircraft's lift coefficient C can be determined. L and the drag coefficient C D .

[0037]

[0038] C D =C Dmin +A*(C L -C LDM ) 2 ……………(2)

[0039] Step 3: From the lift coefficient and drag coefficient, we can determine the lift-to-drag ratio K, the fuselage angle of attack αα, the lift L, the aerodynamic drag Q, and the total drag Q when the aircraft is gliding. 总 .

[0040]

[0041] L=C L *q*S……………………(5)

[0042] Q=C D *q*S……………………(6)

[0043] Q 总 =Q+4*F……………………(7)

[0044] Step 4: Based on the aircraft air-gliding force diagram and the obtained aerodynamic characteristics, the aircraft air-gliding gliding angle γ, air-gliding ratio b, air-gliding horizontal distance J and air-gliding time t can be calculated.

[0045]

[0046] J=H*b……………………(10)

[0047]

[0048] The present invention discloses a method for calculating the air-gliding performance of a turboprop aircraft. The method first determines the physical parameters, environmental parameters and aerodynamic characteristic parameters of the turboprop aircraft, and then combines the influence of the propeller feathering on the aerodynamic characteristics of the aircraft to determine the air-gliding lift coefficient C of the turboprop aircraft. L and the drag coefficient C D , and then determine the lift-to-drag ratio K, fuselage angle of attack α, lift L, aerodynamic drag Q and total drag Q when the aircraft is gliding through force analysis 总 Finally, the aircraft's air-gliding descent angle γ, air-gliding ratio b, air-gliding horizontal distance J and air-gliding time t are calculated.

[0049] This calculation method is intuitive, simple, and has clear theoretical logic, making it easy for aircraft designers to master. This method is comprehensive, versatile, and has broad application value, suitable for medium and large turboprop passenger aircraft, transport aircraft, and related platform aircraft.

[0050] Example:

[0051] Assume a turboprop aircraft, assume a series of required calculation parameters, set the airspeed weight to 50,000kg, 60,000kg, 70,000kg, and 80,000kg, respectively, set the airspeed start altitude to 5,000m, 6,000m, 7,000m, and 8,000m, the flap configuration to 0°, under standard atmospheric conditions, equipped with four engines of a certain type and the propellers parked and feathered. The airspeed performance calculation process is as follows:

[0052] The first step is to determine the relevant parameters of the turboprop aircraft under the air-gliding condition. The specific process is shown in Table 1:

[0053] Table 1

[0054]

[0055]

[0056]

[0057] The second step is to determine the aircraft's lift coefficient C based on the aircraft's basic parameters, flight parameters, and aerodynamic characteristics. Land the drag coefficient C D The specific process is shown in Table 2:

[0058] Table 2

[0059] M(kg) H(m) <![CDATA[C L ]]> <![CDATA[C D ]]> 50000 5000 0.59929521 0.035870947 60000 5000 0.568220644 0.034398103 70000 5000 0.536968509 0.033024928 80000 5000 0.507172145 0.031816655 50000 6000 0.668719884 0.039548637 60000 6000 0.634045519 0.037644941 70000 6000 0.599173016 0.035864946 80000 6000 0.565924926 0.034293543 50000 7000 0.748346673 0.044425354 60000 7000 0.709543512 0.041960966 70000 7000 0.670518619 0.039651032 80000 7000 0.633311565 0.037606088 50000 8000 0.840023984 0.050911555 60000 8000 0.796467184 0.047713591 70000 8000 0.752661489 0.044709711 80000 8000 0.71089633 0.042044072

[0060] The third step is to determine the lift-to-drag ratio K, the fuselage angle of attack α, the lift L, the aerodynamic drag Q and the total drag Q when the aircraft is gliding based on the lift coefficient and the drag coefficient. 总 The specific process is shown in Table 3:

[0061] Table 3

[0062] M(kg) H(m) Wing angle of attack α(°) K L lift (N) QAerodynamic resistance (N) <![CDATA[Q 总 (N)]]> 50000 5000 3.1 16.71 490350 29350 33350 60000 5000 2.8 16.52 588420 35621 39621 70000 5000 2.5 16.26 686490 42221 46221 80000 5000 2.3 15.94 784560 49218 53218 50000 6000 3.8 16.91 490350 29000 33000 60000 6000 3.5 16.84 588420 34936 38936 70000 6000 3.1 16.71 686490 41092 45092 80000 6000 2.8 16.50 784560 47542 51542 50000 7000 4.6 16.85 490350 29109 33109 60000 7000 4.2 16.91 588420 34798 38798 70000 7000 3.8 16.91 686490 40595 44595 80000 7000 3.5 16.84 784560 46587 50587 50000 8000 5.4 16.50 490350 29719 33719 60000 8000 5.0 16.69 588420 35250 39250 70000 8000 4.6 16.83 686490 40779 44779 80000 8000 4.2 16.91 784560 46401 50401

[0063] The fourth step is to calculate the aircraft's glide angle γ, glide ratio b, glide horizontal distance J, and glide time t based on the aircraft's glide force diagram and the obtained aerodynamic characteristics. The specific process is shown in Table 4:

[0064] Table 4

[0065]

[0066]

Claims

1. A method for calculating the air-gliding performance of a fixed-wing turboprop aircraft, characterized in that: include: Based on the characteristics of the turbine engine and propeller, the combined characteristics of the propeller aircraft power unit are determined, and the influence of propeller feathering on the aircraft aerodynamic characteristics is considered. According to the aircraft aerodynamic characteristic parameters and weight characteristic parameters, the required aircraft air-gliding performance is obtained through modeling and adjustment calculations.

2. The calculation method according to claim 1, characterized in that Based on the characteristics of the turbine engine and propeller, the combined characteristics of the propeller aircraft power plant are determined, and the impact of propeller feathering on the aircraft's aerodynamic characteristics is considered. Based on the aircraft's aerodynamic and weight characteristic parameters, the required aircraft air-gliding performance is obtained through modeling, adjustment, and calculation, including: The first step is to obtain the air-slip related parameters of the turboprop aircraft; the air-slip related parameters include: basic parameters, environmental parameters, flight parameters and aerodynamic characteristic parameters; The second step is to determine the aircraft's lift coefficient C based on the aircraft's basic parameters, flight parameters, and aerodynamic characteristics. L and the drag coefficient C D ; The third step is to analyze the air-gliding forces of the turboprop aircraft, taking into account the environmental parameters and the flight state at the moment of engine shutdown: the lift coefficient and drag coefficient are used to determine the lift-to-drag ratio K, the fuselage angle of attack α, the lift L, the aerodynamic drag Q, and the total drag Q during the air-gliding period. 总 ; In the fourth step, the parameters of the first to third steps are introduced into the fixed-wing turboprop aircraft air-gliding model to determine the air-gliding performance of the turboprop aircraft.

3. The calculation method according to claim 2, characterized in that Basic parameters include: the weight M of the turboprop aircraft, the fuselage area S, and the feathering resistance F of the aircraft's single engine blade; environmental parameters include: the aircraft's starting altitude H, air density ρ, and speed of sound V1; flight parameters include: the aircraft's starting speed V t , Mach number M a , speed pressure q; aerodynamic characteristic parameters are obtained from wind tunnel tests, including the lift line slope C under different aircraft attitudes and Mach numbers Lα , zero lift angle of attack α0, minimum drag coefficient C Dmin , induced drag factor A, set drag coefficient C LDM .

4. The calculation method according to claim 3, characterized in that Aircraft airlift coefficient C L and the drag coefficient C D The calculation formula is: C D =C Dmin +A*(C L -C LDM ) 2 ; M—aircraft mass; S—fuselage area; ρ—air density; V t —The speed at which the aircraft starts to glide; C LDM —Set resistance coefficient; C L —lift coefficient; C Dmin —minimum drag coefficient; A—induced drag factor; g—acceleration due to gravity.

5. The calculation method according to claim 4, characterized in that: When the aircraft is gliding, the lift-to-drag ratio K, the fuselage angle of attack α, the lift L, the aerodynamic drag Q and the total drag Q 总 The calculation formula is: L=C L *q*S; Q=C D *q*S; Q 总 =Q+4*F; C D —Drag coefficient; F—feathering resistance of a single engine blade; q—speed pressure; α0—zero lift angle of attack.

6. The calculation method according to claim 5, characterized in that The air-gliding performance of a turboprop aircraft includes: the aircraft's air-gliding glide angle γ, the air-gliding ratio b, the air-gliding horizontal distance J and the air-gliding time t.

7. The calculation method according to claim 6, characterized in that: The calculation formulas for the aircraft's air-gliding glideslope angle γ, air-gliding ratio b, air-gliding horizontal distance J, and air-gliding time t are as follows: J = H * b; 8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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