Aerodynamic performance rapid prediction method suitable for small propulsion propeller

Abstract

The invention belongs to the technical field of performance calculation of a small model airplane power system, and particularly relates to a quick aerodynamic performance prediction method suitable for a small propulsion propeller, which comprises the following steps of: 1, determining the boundary dimension and calculation conditions of the propeller; 2, the aerodynamic performance of the airfoil profile is calculated; 3, the aerodynamic performance of the blade is calculated; and 4, correcting a propeller hub and a propeller front fuselage, and finally obtaining the aerodynamic performance of the small propulsion propeller. According to the method, the aerodynamic performance of the propeller blades is calculated based on the vortex theory, calculation of the aerodynamic performance of the propeller hub and interference correction of the fuselage in front of the propeller are added according to experience, and therefore the actual aerodynamic performance of the propeller can be rapidly and accurately obtained, and data support is provided for overall design iteration of small unmanned aerial vehicles and model airplanes.

Description

Technical Field

[0001] The invention belongs to the technical field of performance calculation of power systems of small-sized model aircraft, and in particular relates to a method for quickly predicting aerodynamic performance suitable for small-sized propellers. Background Art

[0002] At present, propellers, as a power device with simple structure and mature technical reserves, are widely used in the propulsion power device of small model aircraft. The aerodynamic performance of the propeller determines the efficiency of the propulsion system and even affects the overall performance indicators of the model aircraft. Therefore, for the propulsion propeller power system device of a small model aircraft, how to quickly and accurately calculate the aerodynamic performance is of great significance for the optimization of propeller shape, propeller-engine matching design, and the improvement of the overall performance of the model aircraft.

[0003] There are currently two methods for calculating propeller performance: engineering algorithms and numerical simulation calculations. The engineering algorithm can quickly evaluate the performance of the blades, but it cannot simulate the hub performance calculation and the interference of the fuselage in front of the propeller. The propeller hub will produce a certain amount of resistance and torque after rotation, which will reduce the overall thrust of the propeller and increase the torque, both of which will reduce the efficiency of the propeller. Because of the existence of the fuselage in front of the propeller, the windward area of ​​the propeller will be reduced, which will affect the overall thrust of the propeller. Therefore, ignoring the interference of the propeller hub and the fuselage in front of the propeller will lead to an overly optimistic evaluation of the propeller's performance during the propeller optimization process, so that the final model aircraft power system does not have the high efficiency after optimization.

[0004] Numerical simulation can be used to calculate the propeller aerodynamic performance, hub performance and the interference effect of the propeller front fuselage with high precision. However, since numerical simulation requires grid generation and RANS or large eddy simulation iterative calculations for different optimized blade shapes and different hub and propeller front fuselage shapes, it consumes a lot of computing resources and computing time. Therefore, a faster and more convenient calculation method is needed to complete the rapid evaluation of propeller performance in the propeller optimization design stage. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] The technical problem to be solved by the present invention is: in order to improve the accuracy and rapidity of propeller power system performance evaluation in the early stage of the overall design of small electric propulsion UAVs and model aircraft, how to provide a method for quickly predicting the aerodynamic performance of small propulsion propellers.

[0007] (II) Technical solution

[0008] In order to solve the above technical problems, the present invention provides a method for quickly predicting aerodynamic performance of a small propulsion propeller, the method comprising the following steps:

[0009] Step 1: Determine the propeller dimensions and calculation conditions;

[0010] Step 2: Calculate the aerodynamic performance of the airfoil;

[0011] Step 3: Calculate the aerodynamic performance of the blade;

[0012] Step 4: Modify the hub and the fuselage in front of the propeller to finally obtain the aerodynamic performance of the small propulsion propeller.

[0013] Wherein, in the step 1, the outer dimensions of the propeller and the calculation conditions are determined as follows:

[0014] Step 1.1, according to the propeller three-dimensional digital model and the blade design file, determine the spanwise position, airfoil type, chord length and installation angle of multiple sections along the spanwise position;

[0015] Step 1.2: According to the calculation task, determine the calculation parameters, including flight altitude, flight speed, and propeller rotation speed.

[0016] In step 1.1, the blade is divided into N sections along the span direction according to the blade design file, and the relative positions of each station are given respectively. Absolute position r i , airfoil type, chord length b i and the installation angle ψ i The data matrix of the propeller blade number N B , propeller diameter D lxj , the axial windward area S1 of the propeller hub, the circumferential windward area S2 of the propeller hub and the diameter D of the propeller front body ds , where: i represents the i-th section, i=1, 2, 3...N.

[0017] Among them, in step 1.2, according to the calculation task, the flight altitude H, the flight speed V, and the rotation speed ω of the propeller are determined to prepare parameters for subsequent calculations.

[0018] Wherein, in the step 2, the aerodynamic performance of the airfoil is calculated, and the steps are as follows:

[0019] Step 2.1, based on the propeller's flight speed, rotation speed and chord length of each section, estimate the Reynolds number range during use;

[0020] Step 2.2: By using numerical calculation software, accurately calculate the aerodynamic performance of each airfoil within the Reynolds number range in step 2.1.

[0021] Wherein, in step 2.1, the Reynolds number Re of each section of the blade is calculated. i , the expression is (1):

[0022]

[0023] Where ρ and μ are the atmospheric density and viscosity coefficient at the flight altitude H; U i is the vector sum of the airfoil rotation speed and the propeller flight speed at the i-th section; since the aerodynamic performance rapid prediction method is aimed at the preliminary design stage, the angle between the propeller thrust axis direction and the flight direction is not considered, so the propeller rotation speed direction and the flight speed direction are orthogonal, U i The expression of is (2):

[0024]

[0025] Among them, in the step 2.2, the aerodynamic data under different Reynolds numbers are obtained by performing grid generation and RANS numerical simulation on each airfoil, including the lift coefficient and drag coefficient under different Reynolds numbers and different angles of attack, to form an aerodynamic performance table of the airfoil; the Reynolds number does not need to correspond one-to-one with the calculation in step 2.1, but only needs to include the entire range, and the actual Reynolds number and angle of attack can be interpolated when finally used.

[0026] Wherein, in the step 3, the aerodynamic performance of the blade is calculated, and the steps are as follows:

[0027] Step 3.1, calculate the circumferential velocity, geometric angle of attack, and solidity of each section;

[0028] Step 3.2, determine the angle of attack correction of each section according to eddy current theory;

[0029] Step 3.3, determine the aerodynamic performance parameters of each section, including thrust coefficient and torque coefficient;

[0030] Step 3.4: Based on the aerodynamic data of step 3.3, integrate to obtain the aerodynamic performance of the blade.

[0031] Among them, in step 3.1, the circumferential velocity at each section is Geometric angle of attack Solidity i The expressions are as follows:

[0032]

[0033]

[0034]

[0035] In step 3.2, the angle of attack correction α′ of each section is determined according to the vortex theory. i , the steps are as follows:

[0036] Assume that the angle of attack correction at the i-th section is Then the angle of attack θ at this section is i The calculation expression is formula (6):

[0037]

[0038] According to the aerodynamic performance table of the airfoil calculated in step 2.2, the interpolation calculation is performed to obtain the value of the airfoil at an angle of attack of θ. i , Reynolds number is Re i The lift coefficient Cl i and the drag coefficient Cd i ;

[0039] Finally, according to the eddy current theory, α i 'Equation, use Newton iteration to calculate the angle of attack correction α' of each section i , the calculation expression is shown in formula (7):

[0040]

[0041] In step 3.3, the corrected cross-sectional velocity U′ is calculated. i , the calculation expression is formula (8):

[0042]

[0043] Thrust T of each section i and torque Q i The expressions are as follows:

[0044]

[0045]

[0046] In step 3.4, the thrust and torque of the blade are obtained by integration, wherein the calculation expressions are equations (11) and (12):

[0047]

[0048]

[0049] Wherein, in the step 4, the hub and the fuselage in front of the propeller are corrected, and finally the aerodynamic performance of the small propulsion propeller is obtained;

[0050] The hub is corrected for the thrust and torque of the blades. Here, the correction is simplified. After the hub rotates, it will generate a certain resistance and torque. The resistance will reduce the thrust of the propeller, and the torque will increase the torque of the propeller, resulting in a certain degree of reduction in the efficiency of the propeller. Therefore, the influence of the hub cannot be ignored. According to the experience of numerical simulation, the resistance generated by the hub is estimated using formula (13), and the torque value is estimated using formula (14):

[0051]

[0052]

[0053] Where: S1 is the windward area of ​​the propeller hub axial direction, unit is dm 2 ; S2 is the windward area of ​​the propeller hub circumference, in dm 2 , so far the propeller hub correction is completed;

[0054] The correction method for the propeller front fuselage is as follows: the radial range of the propeller blocked by the cross-sectional area of ​​the propeller front fuselage is assumed to have zero thrust and unchanged torque at the blocked position; therefore, the thrust value T generated within this range is calculated. 遮挡 , subtracted from the aerodynamic performance of the whole propeller, the correction of the fuselage in front of the propeller is completed; finally, the thrust T and torque Q of the small propulsion propeller are obtained, and the calculation expressions are formula (15) and formula (16).

[0055] T=T p -T 桨毂 -T 遮挡 (15)

[0056] Q=Q p +Q 桨毂 (16).

[0057] (III) Beneficial effects

[0058] In the early stage of the overall design of small electric propulsion UAVs and model aircraft, the present invention proposes a method for rapid prediction of aerodynamic performance suitable for small propulsion propellers in order to improve the accuracy and rapidity of propeller power system performance evaluation. Compared with the prior art, the present invention calculates the aerodynamic performance of propeller blades based on vortex theory, and adds the calculation of hub aerodynamic performance and correction of propeller front fuselage interference based on experience, so that the actual aerodynamic performance of the propeller can be obtained quickly and accurately, providing data support for the overall design iteration of small UAVs and model aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 This is a schematic diagram of the propeller shape.

[0060] Figure 2 Distribution diagram of propeller chord length and installation angle.

[0061] Figure 3 Schematic diagram of the blade element velocity triangle of the propeller cross section.

[0062] Figure 4 This is a comparison chart of propeller thrust calculation results.

[0063] Figure 5 This is a comparison chart of propeller torque calculation results. DETAILED DESCRIPTION

[0064] In order to make the purpose, content, and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below in conjunction with the accompanying drawings and examples.

[0065] In order to solve the above technical problems, the present invention provides a method for quickly predicting aerodynamic performance of a small propulsion propeller, the method comprising the following steps:

[0066] Step 1: Determine the propeller dimensions and calculation conditions;

[0067] Step 2: Calculate the aerodynamic performance of the airfoil;

[0068] Step 3: Calculate the aerodynamic performance of the blade;

[0069] Step 4: Modify the hub and the fuselage in front of the propeller to finally obtain the aerodynamic performance of the small propulsion propeller.

[0070] Wherein, in the step 1, the outer dimensions of the propeller and the calculation conditions are determined as follows:

[0071] Step 1.1, according to the propeller three-dimensional digital model and the blade design file, determine the spanwise position, airfoil type, chord length and installation angle of multiple sections along the spanwise position;

[0072] Step 1.2: According to the calculation task, determine the calculation parameters, including flight altitude, flight speed, and propeller rotation speed.

[0073] In step 1.1, the blade is divided into N sections along the span direction according to the blade design file, and the relative positions of each station are given respectively. Absolute position r i , airfoil type, chord length b i and the installation angle ψ i The data matrix of the propeller blade number N B , propeller diameter D lxj , the axial windward area S1 of the propeller hub, the circumferential windward area S2 of the propeller hub and the diameter D of the propeller front body ds, where: i represents the i-th section, i=1, 2, 3...N.

[0074] Among them, in step 1.2, according to the calculation task, the flight altitude H, the flight speed V, and the rotation speed ω of the propeller are determined to prepare parameters for subsequent calculations.

[0075] Wherein, in the step 2, the aerodynamic performance of the airfoil is calculated, and the steps are as follows:

[0076] Step 2.1, based on the propeller's flight speed, rotation speed and chord length of each section, estimate the Reynolds number range during use;

[0077] Step 2.2: By using numerical calculation software, accurately calculate the aerodynamic performance of each airfoil within the Reynolds number range in step 2.1.

[0078] Wherein, in step 2.1, the Reynolds number Re of each section of the blade is calculated. i , the expression is (1):

[0079]

[0080] Where ρ and μ are the atmospheric density and viscosity coefficient at the flight altitude H; U i is the vector sum of the airfoil rotation speed and the propeller flight speed at the i-th section; since the aerodynamic performance rapid prediction method is aimed at the preliminary design stage, the angle between the propeller thrust axis direction and the flight direction is not considered, so the propeller rotation speed direction and the flight speed direction are orthogonal, U i The expression of is (2):

[0081]

[0082] Among them, in the step 2.2, the aerodynamic data under different Reynolds numbers are obtained by performing grid generation and RANS numerical simulation on each airfoil, including the lift coefficient and drag coefficient under different Reynolds numbers and different angles of attack, to form an aerodynamic performance table of the airfoil; the Reynolds number does not need to correspond one-to-one with the calculation in step 2.1, but only needs to include the entire range, and the actual Reynolds number and angle of attack can be interpolated when finally used.

[0083] Wherein, in the step 3, the aerodynamic performance of the blade is calculated, and the steps are as follows:

[0084] Step 3.1, calculate the circumferential velocity, geometric angle of attack, and solidity of each section;

[0085] Step 3.2, determine the angle of attack correction of each section according to eddy current theory;

[0086] Step 3.3, determine the aerodynamic performance parameters of each section, including thrust coefficient and torque coefficient;

[0087] Step 3.4: Based on the aerodynamic data of step 3.3, integrate to obtain the aerodynamic performance of the blade.

[0088] Wherein, in step 3.1, the circumferential velocity V at each cross section is ti , geometric angle of attack Solidity i The expressions are as follows:

[0089]

[0090]

[0091]

[0092] In step 3.2, the angle of attack correction α′ of each section is determined according to the vortex theory. i , the steps are as follows:

[0093] Assume that the angle of attack correction at the i-th section is Then the angle of attack θ at this section is i The calculation expression is formula (6):

[0094]

[0095] According to the aerodynamic performance table of the airfoil calculated in step 2.2, the interpolation calculation is performed to obtain the value of the airfoil at an angle of attack of θ. i , Reynolds number is Re i The lift coefficient Cl i and the drag coefficient Cd i ;

[0096] Finally, according to the eddy current theory, α i 'Equation, use Newton iteration to calculate the angle of attack correction α' of each section i , the calculation expression is shown in formula (7):

[0097]

[0098] In step 3.3, the corrected cross-sectional velocity U′ is calculated. i , the calculation expression is formula (8):

[0099]

[0100] Thrust T of each section i and torque Q i The expressions are as follows:

[0101]

[0102]

[0103] In step 3.4, the thrust and torque of the blade are obtained by integration, wherein the calculation expressions are equations (11) and (12):

[0104]

[0105]

[0106] Wherein, in the step 4, the hub and the fuselage in front of the propeller are corrected, and finally the aerodynamic performance of the small propulsion propeller is obtained;

[0107] The hub is corrected for the thrust and torque of the blades. Here, the correction is simplified. After the hub rotates, it will generate a certain resistance and torque. The resistance will reduce the thrust of the propeller, and the torque will increase the torque of the propeller, resulting in a certain degree of reduction in the efficiency of the propeller. Therefore, the influence of the hub cannot be ignored. According to the experience of numerical simulation, the resistance generated by the hub is estimated using formula (13), and the torque value is estimated using formula (14):

[0108]

[0109]

[0110] Where: S1 is the windward area of ​​the propeller hub axial direction, unit is dm 2 ; S2 is the windward area of ​​the propeller hub circumference, in dm 2 , so far the propeller hub correction is completed;

[0111] The correction method for the propeller front fuselage is as follows: the radial range of the propeller blocked by the cross-sectional area of ​​the propeller front fuselage is assumed to have zero thrust and unchanged torque at the blocked position; therefore, the thrust value T generated within this range is calculated. 遮挡 , subtracted from the aerodynamic performance of the whole propeller, the correction of the fuselage in front of the propeller is completed; finally, the thrust T and torque Q of the small propulsion propeller are obtained, and the calculation expressions are formula (15) and formula (16).

[0112] T=T p -T 桨毂 -T 遮挡 (15)

[0113] Q=Q p +Q 桨毂 (16).

[0114] Example 1

[0115] The present invention calculates the aerodynamic performance of propeller blades based on vortex theory, and adds hub correction and front fuselage interference correction based on experience, so as to quickly and accurately obtain the actual aerodynamic performance of the propeller, and provide data support for the overall design iteration of small UAVs and aircraft models. Specifically, the present invention discloses a method for quickly predicting the aerodynamic performance of small propulsion propellers, comprising the following steps:

[0116] Step 1: Determine the propeller's dimensions and calculation conditions.

[0117] According to the three-dimensional digital model of propeller J1 and the design file of the blade, the blade is divided into 8 sections along the span direction, and the relative positions of each station are given respectively. Absolute position r i , airfoil type, chord length b i and the installation angle ψ i The data matrix is: i represents the i-th section, i = (1,2,3...8). The blade design range is the spanwise 0.3-1.0 section, the cross-sectional shape is the Clark-Y airfoil, and the blade installation angle and chord length distribution are as follows: Figure 2 The number of blades of the propeller is N. B =2, propeller diameter D lxj = 0.5m, propeller hub axial windward area S1 = 0.225dm 2 , the windward area of ​​the propeller hub circumference S2 = 0.09dm 2 The diameter of the fuselage in front of the propeller can be selected in 3 states: D ds1 =0m, D ds2 =0.1m and D ds3 =0.2m.

[0118] The calculation parameters are determined according to the required calculation tasks, such as flight altitude H=0km, flight speed V=30m / s, and propeller rotation speed 8000rpm.

[0119] Step 2: Use numerical simulation methods to quickly and accurately calculate the aerodynamic performance of the airfoil.

[0120] According to expression (1), the Reynolds number Re of the blade in each cross section is calculated: i :

[0121]

[0122] Where, ρ and μ are the atmospheric density and viscosity coefficient at the flight altitude of 0 km; U iis the vector sum of the airfoil rotation speed and the propeller flight speed at the i-th section. In the early stage of the optimization design, the Reynolds number is calculated without considering the angle between the propeller thrust axis and the flight direction. Therefore, the propeller speed direction and the flight speed direction are orthogonal. i The expression of is (2):

[0123]

[0124] According to the calculation results of the Reynolds number, the Clark-Y airfoil is meshed and RANS numerically simulated to obtain the lift coefficient and drag coefficient under different Reynolds numbers and different angles of attack. In this calculation process, the Reynolds number does not need to correspond one-to-one with the calculation in expression (1), but only needs to include the entire range. The actual Reynolds number and angle of attack can be interpolated when finally used.

[0125] Step 3: Calculate the aerodynamic performance of the blade using vortex theory.

[0126] First, according to the distribution of the blades, the circumferential velocity V at each section is calculated using formulas (3), (4), and (5): ti , geometric angle of attack Solidity i .

[0127]

[0128]

[0129]

[0130] In order to accurately calculate the actual angle of attack of the blade at each section, the angle of attack correction α′ at each section is determined by vortex theory. i .

[0131] Assume that the angle of attack correction at the i-th section is Then the angle of attack θ at this section is i The calculation expression is formula (6):

[0132]

[0133] According to the aerodynamic performance table of the airfoil calculated in step 2, interpolate and calculate the Clark-Y airfoil at an angle of attack of θ i , Reynolds number is Re i The lift coefficient Cl i and the drag coefficient Cd i .

[0134] According to the vortex theory, α i 'Equation, use Newton iteration to calculate the angle of attack correction α' of each sectioni , the calculation expression is shown in the following formula (7):

[0135]

[0136] Afterwards, the actual incoming flow velocity U′ of each section is further corrected according to the geometric relationship of the velocity triangle of the blade section. i , the calculation expression is formula (8):

[0137]

[0138] Thrust T of each section i and torque Q i The expressions of are shown in formula (9) and formula (10):

[0139]

[0140]

[0141] The thrust and torque distribution of the blade cross section is integrated to obtain the thrust and torque of the blade, where the calculation expressions are shown in equations (11) and (12):

[0142]

[0143]

[0144] Step 4: Based on practical experience, make corrections to the hub and the fuselage in front of the propeller to ultimately obtain the aerodynamic performance of the small propulsion propeller.

[0145] After the propeller hub rotates, it will generate a certain amount of resistance and torque. The resistance will reduce the propeller thrust, and the torque will increase the propeller torque, resulting in a certain degree of reduction in propeller efficiency. Therefore, the influence of the hub cannot be ignored. According to the experience of numerical simulation, the resistance generated by the hub can be estimated using formula (13), and the torque value can be estimated using formula (14):

[0146]

[0147]

[0148] Where: S1 is the windward area of ​​the propeller hub axial direction, unit is dm 2 ; S2 is the windward area of ​​the propeller hub circumference, in dm 2 , the propeller hub correction is now completed.

[0149] The main steps of the correction method for the propeller front fuselage are as follows: the radial range of the propeller blocked by the cross-sectional area of ​​the propeller front fuselage is assumed to have zero thrust and unchanged torque at the blocked position. Therefore, the thrust value T generated within this range is calculated. 遮挡 , subtracted from the aerodynamic performance of the full propeller, the correction of the fuselage in front of the propeller is completed. Finally, the thrust T and torque Q of the small propulsion propeller are obtained, and the calculation expressions are formula (15) and formula (16).

[0150] T=T p -T 桨毂 -T 遮挡 (15)

[0151] Q=Q p +Q 桨毂 (16)

[0152] In order to verify the generality of the present invention, three propeller front fuselage diameters were selected: D ds1 =0m, D ds2 =0.1m and D ds3 =0.2m.

[0153] Data calculations were performed for three different working conditions, and the calculation results were compared with the numerical simulation results. Figure 4 and Figure 5 As shown in the figure, it can be seen from the data that under the action of three different propeller front bodies, the aerodynamic performance of the propeller calculated by the present invention is close to the numerical simulation results, wherein the maximum thrust error is about 6%, and the maximum torque error is within 3%. It can be shown that the present invention has good accuracy for the rapid prediction of the aerodynamic performance of small propulsion propellers, and can be used for the preliminary calculation of propeller optimization.

[0154] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for rapid prediction of aerodynamic performance of a small propeller, characterized in that: The method comprises the following steps: Step 1: Determine the propeller dimensions and calculation conditions; Step 2: Calculate the aerodynamic performance of the airfoil; Step 3: Calculate the aerodynamic performance of the blade; Step 4: Modify the hub and the fuselage in front of the propeller to finally obtain the aerodynamic performance of the small propulsion propeller.

2. The method for rapid prediction of aerodynamic performance of a small propulsion propeller according to claim 1, characterized in that: In step 1, the dimensions of the propeller and the calculation conditions are determined as follows: Step 1.1, according to the propeller three-dimensional digital model and the blade design file, determine the spanwise position, airfoil type, chord length and installation angle of multiple sections along the spanwise position; Step 1.2: According to the calculation task, determine the calculation parameters, including flight altitude, flight speed, and propeller rotation speed.

3. The method for rapid prediction of aerodynamic performance of a small propulsion propeller according to claim 1, characterized in that: In step 1.1, the blade is divided into N sections along the spanwise position according to the blade design file, and the relative positions of each station are given respectively. Absolute position r i , airfoil type, chord length b i and the installation angle ψ i The data matrix of the propeller blade number N B , propeller diameter D lxj , the axial windward area S1 of the propeller hub, the circumferential windward area S2 of the propeller hub and the diameter D of the propeller front body ds , where: i represents the i-th section, i=1, 2, 3...N.

4. The method for rapid prediction of aerodynamic performance of a small propulsion propeller according to claim 2, characterized in that: In step 1.2, according to the calculation task, the flight altitude H, the flight speed V, and the rotation speed ω of the propeller are determined to prepare parameters for subsequent calculations.

5. The method for rapid prediction of aerodynamic performance of a small propeller according to claim 4, characterized in that: In the second step, the aerodynamic performance of the airfoil is calculated as follows: Step 2.1, based on the propeller's flight speed, rotation speed and chord length of each section, estimate the Reynolds number range during use; Step 2.2: By using numerical calculation software, accurately calculate the aerodynamic performance of each airfoil within the Reynolds number range in step 2.

1.

6. The method for rapid prediction of aerodynamic performance of a small propeller according to claim 5, characterized in that: In step 2.1, the Reynolds number Re of each section of the blade is calculated. i , the expression is (1): Where ρ and μ are the atmospheric density and viscosity coefficient at the flight altitude H; U i is the vector sum of the airfoil rotation speed and the propeller flight speed at the i-th section; since the aerodynamic performance rapid prediction method is aimed at the preliminary design stage, the angle between the propeller thrust axis direction and the flight direction is not considered, so the propeller rotation speed direction and the flight speed direction are orthogonal, U i The expression of is (2):

7. The method for rapid prediction of aerodynamic performance of a small propulsion propeller according to claim 6, characterized in that: In the step 2.2, aerodynamic data under different Reynolds numbers are obtained by performing grid generation and RANS numerical simulation on each airfoil, including lift coefficient and drag coefficient under different Reynolds numbers and different angles of attack, to form an aerodynamic performance table of the airfoil; the Reynolds number does not need to correspond one-to-one with the calculation in step 2.1, but only needs to include the entire range, and the actual Reynolds number and angle of attack can be interpolated when finally used.

8. The method for rapid prediction of aerodynamic performance of a small propulsion propeller according to claim 7, characterized in that: In step 3, the aerodynamic performance of the blade is calculated as follows: Step 3.1, calculate the circumferential velocity, geometric angle of attack, and solidity of each section; Step 3.2, determine the angle of attack correction of each section according to eddy current theory; Step 3.3, determine the aerodynamic performance parameters of each section, including thrust coefficient and torque coefficient; Step 3.4: Based on the aerodynamic data of step 3.3, integrate to obtain the aerodynamic performance of the blade.

9. The method for rapid prediction of aerodynamic performance of a small propulsion propeller according to claim 8, characterized in that: In step 3.1, the circumferential velocity at each section Geometric angle of attack Solidity i The expressions are as follows: In step 3.2, the angle of attack correction α of each section is determined according to the vortex theory. i ′, the steps are as follows: Assume that the angle of attack correction at the i-th section is Then the angle of attack θ at this section is i The calculation expression is formula (6): According to the aerodynamic performance table of the airfoil calculated in step 2.2, the interpolation calculation is performed to obtain the value of the airfoil at an angle of attack of θ. i , Reynolds number is Re i The lift coefficient Cl i and the drag coefficient Cd i ; Finally, according to the eddy current theory, α i ′ equation, and use Newton iteration to calculate the angle of attack correction α of each section i ′, the calculation expression is shown in formula (7): In step 3.3, the corrected cross-sectional velocity U is calculated. i ′, the calculation expression is formula (8): Thrust T of each section i and torque Q i The expressions are as follows: In step 3.4, the thrust and torque of the blade are obtained by integration, wherein the calculation expressions are equations (11) and (12):

10. The method for rapid prediction of aerodynamic performance of a small propulsion propeller according to claim 9, characterized in that: In the step 4, the hub and the fuselage in front of the propeller are corrected, and finally the aerodynamic performance of the small propulsion propeller is obtained; The hub is corrected according to the thrust and torque of the blades, and the correction is simplified here; After the hub rotates, it will generate a certain amount of resistance and torque. The resistance will reduce the thrust of the propeller, and the torque will increase the torque of the propeller, resulting in a certain degree of reduction in the efficiency of the propeller. Therefore, the influence of the hub cannot be ignored. According to the experience of numerical simulation, the resistance generated by the hub is estimated using formula (13), and the torque value is estimated using formula (14): Where: S1 is the windward area of ​​the propeller hub axial direction, unit is dm 2 ; S2 is the windward area of ​​the propeller hub circumference, in dm 2 , so far the propeller hub correction is completed; The correction method for the propeller front fuselage is as follows: the radial range of the propeller blocked by the cross-sectional area of ​​the propeller front fuselage is assumed to have zero thrust and unchanged torque at the blocked position; therefore, the thrust value T generated within this range is calculated. 遮挡 , subtracted from the aerodynamic performance of the whole propeller, the correction of the fuselage in front of the propeller is completed; finally, the thrust T and torque Q of the small propulsion propeller are obtained, and the calculation expressions are formula (15) and formula (16). T=T p -T 桨毂 -T 遮挡 (15) Q=Q p +Q 桨毂 (16)。

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