Performance evaluation method for electrically driven ducted fan based on one-dimensional normal problem analysis

Abstract

The invention provides an electrically driven ducted fan performance evaluation method based on one-dimensional positive problem analysis, and belongs to the field of electrically driven ducted fan evaluation.The electrically driven ducted fan performance evaluation method comprises the steps that four calculation stations are arranged in an electrically driven ducted fan control body along a streamline, and an electrically driven ducted fan parameterized model is obtained; according to the electrically-driven ducted fan parameterized model, the total temperature and total pressure of outlet airflow and the ducted fan rim work are obtained; according to the total temperature and pressure of the outlet airflow and a reducing nozzle flow equation, the absolute velocity of the nozzle outlet airflow is obtained; obtaining the thrust of the ducted fan according to the absolute speed of the airflow at the outlet of the spray pipe in combination with the Mach number of the outlet and the continuity equation of the mass flow of the electrically-driven ducted fan; obtaining the force effect of the ducted fan according to the thrust of the ducted fan; the rotating speed of the ducted fan is obtained according to the ducted fan rim work, the torque of the ducted fan is obtained based on the combination of the rotating speed of the ducted fan and the power of the ducted fan, and the propulsion performance of the electrically-driven ducted fan is evaluated by rapidly and accurately calculating the thrust and the power of the electrically-driven ducted fan.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric ducted fan aerodynamic analysis, and particularly relates to a positive problem analysis method for aerodynamic-propulsion coupling of a ducted fan. BACKGROUND

[0002] An electric ducted fan is an axial flow impeller driven by an electric motor, which has good safety and propulsion performance through the interaction between the outer duct and the paddle disc. Compared with the traditional turbofan engine, the electric ducted fan has a compact structure and zero carbon emission characteristics, and is the preferred power device for future green aviation.

[0003] The existing technology has the following problems in the evaluation method of the electric ducted fan: in the low-speed field, the ducted propeller aerodynamic performance evaluation method under the potential flow theory system has not effectively integrated the compressible flow effect; in the high-speed field, the quasi-three-dimensional aerodynamic performance evaluation method taking the meridional flow surface as the core can handle transonic flow, but the thrust calculation still relies on empirical formula correction. Both methods do not establish a quantitative mapping relationship between blade geometric parameters, aerodynamic characteristic quantities and propulsion performance. Three-dimensional computational fluid dynamics numerical simulation needs a large number of iterative calculations on the target, and the calculation process is lengthy, which cannot quickly evaluate the performance of the electric ducted fan. Therefore, how to quickly and accurately calculate the thrust and power parameters of the ducted fan becomes a key problem in evaluating the propulsion performance of the ducted fan. SUMMARY

[0004] To solve the above problems, the present application provides a performance evaluation method for an electric ducted fan based on one-dimensional positive problem analysis, which evaluates the propulsion performance of the electric ducted fan by quickly and accurately calculating the thrust and power of the electric ducted fan, and specifically includes: A performance evaluation method for an electric ducted fan based on one-dimensional positive problem analysis, the performance evaluation parameters of the electric ducted fan including ducted fan torque and ducted fan force efficiency, the method comprising: S1, four calculation stations are arranged along the streamline in the control body of the electric ducted fan to obtain a parameterized model of the electric ducted fan; S2, the total temperature and total pressure of the outlet airflow and the rim power of the ducted fan are obtained according to the parameterized model of the electric ducted fan; S3, the absolute speed of the airflow at the outlet of the nozzle is obtained according to the total temperature and total pressure of the outlet airflow and the converging-diverging nozzle flow equation; S4, the ducted fan thrust is obtained according to the absolute speed of the airflow at the outlet of the nozzle and the continuity equation of the outlet Mach number and the mass flow rate of the electric ducted fan; the ducted fan force efficiency is obtained according to the ducted fan thrust; the ducted fan rotational speed is obtained according to the ducted fan rim power, and the ducted fan torque is obtained based on the ducted fan power and the ducted fan rotational speed.

[0005] Optionally, the four calculation stations in the S1 include: The four calculation stations include a 1-1 cross section, a 2-2 cross section, a 3-3 cross section, and a 4-4 cross section. The 1-1 cross section is an inlet cross section of the electrically driven ducted fan. The 2-2 cross section is a blade leading edge cross section of the electrically driven ducted fan. The 3-3 cross section is an outlet guide vane trailing edge cross section of the electrically driven ducted fan. The 4-4 cross section is a nozzle outlet cross section of the electrically driven ducted fan. The 0-0 cross section is located in front of the electrically driven ducted fan at an infinite distance without disturbance.

[0006] Optionally, the electrically driven ducted fan parameterization model in the S1 includes: The airflow is set as a steady flow, the flow loss in the inlet duct and the nozzle is defined as 0, and the default airflow is isentropically expanded in the converging nozzle.

[0007] Optionally, the total temperature and total pressure of the outlet airflow according to the electrically driven ducted fan parameterization model in the S2 include: S201, obtaining the total temperature at the outlet guide vane trailing edge cross section according to the isentropic efficiency expression The formula includes formula (1): ; (1) Wherein, is the isentropic efficiency, is the design point total pressure ratio, is the total temperature at the 1-1 cross section; is the total temperature at the 3-3 cross section; k is the specific heat ratio of gas; S202, obtaining the total pressure of the 3-3 cross section airflow According to the design point total pressure ratio ; S203, the total temperature and total pressure of the outlet airflow are the total temperature and total pressure at the 4-4 cross section, based on the isentropic expansion of the airflow in the nozzle, T3 =T4 , P3 =P4 .

[0008] Optionally, the ducted fan wheel rim work calculation formula of the S2 includes (2): ; (2) Wherein, L u is the ducted fan wheel rim work; R is the gas constant.

[0009] Optionally, the S3 in the formula (2) is obtained according to the total temperature and total pressure of the outlet airflow combined with the flow equation of the converging-diverging nozzle, and the absolute velocity C of the airflow at the outlet of the nozzle is obtained. 4is The formula is formula (3): ; (3) P4 is the gas static pressure of the 4-4 section, P4=P0, and P0 is the gas static pressure of the 0-0 section.

[0010] Optionally, the S4 in the formula (2) is obtained according to the absolute velocity C of the airflow at the outlet of the nozzle, combined with the continuity equation of the outlet Mach number and the mass flow of the electrically-driven ducted fan, and the thrust of the ducted fan is obtained. S401, the outlet flow coefficient is calculated based on the outlet Mach number, and the calculation formula of the outlet flow coefficient is formula (4): ; (4) Ma4 is the outlet Mach number, and λ4 is the outlet flow coefficient. S402, the outlet flow function is obtained based on the outlet flow coefficient; S403, the outlet flow function is brought into the continuity equation of the mass flow of the electrically-driven ducted fan, and the thrust of the ducted fan is obtained.

[0011] Optionally, the formula (2) in the S402 is obtained based on the outlet flow coefficient to obtain the outlet flow function: ; (5) Wherein, q(λ4) is the outlet flow function; The formula of the thrust of the ducted fan in the S403 is formula (6): ; (6) Wherein, F fan is the thrust of the ducted fan, α4 is the included angle between the airflow flow direction at the 4-4 section and the axial direction, and V0 is the incoming flow speed of the electrically-driven ducted fan; Wherein, ; Wherein, ; Wherein, m4 is the mass flow at the 4-4 section, and A4 is the area through which the airflow passes at the 4-4 section.

[0012] Optionally, the S4 in the formula (2) is obtained according to the thrust of the ducted fan to obtain the force efficiency of the ducted fan. S404, the ducted fan power P fan is calculated, and the formula of the ducted fan power is formula (7): ; (7) S405, obtain the ducted fan force efficiency based on the ducted fan power and the ducted fan thrust, and the formula of the ducted fan force efficiency is formula (8): (8) g is the acceleration of gravity.

[0013] Compared with the prior art, the above technical scheme has at least the following beneficial effects: The present problem analysis method establishes a force efficiency dominated electric ducted fan aerodynamic-propulsion coupling parameterized model, reveals the coupling correlation law of ducted fan aerodynamic parameters and propulsion performance, realizes the paradigm conversion of electric ducted fan flow parameters to propulsion characteristic parameters, so that the electric ducted fan aerodynamic design is directly related to the propulsion performance, and the rapid performance evaluation of the aviation electric propulsion system components can be effectively assisted. The analysis and calculation results are consistent with the change trend of the three-dimensional numerical simulation and the ground test results, the relative deviation of the thrust and the test conversion results is effectively controlled within 5%, and the relative deviation of the force efficiency and the three-dimensional numerical simulation results is less than 1.5%. In addition, the present method is based on one-dimensional problem analysis, and the electric ducted fan force efficiency and torque can be quickly calculated. BRIEF DESCRIPTION OF DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0015] Figure 1 The flow chart of the analysis of one embodiment of the present application is shown in the figure; Figure 2 The distribution diagram of four calculation stations of one embodiment of the present application is shown in the figure; Figure 3 Fig. (a) in the figure is a curve comparison diagram of the outlet axial velocity and mass flow characteristic curves in the one-dimensional analysis and three-dimensional numerical simulation results; Figure 3 Fig. (b) in the figure is a curve comparison diagram of the thrust and power characteristic curves in the one-dimensional analysis and three-dimensional numerical simulation results; Figure 3 Fig. (c) in the figure is a curve comparison diagram of the electric ducted fan force efficiency in the one-dimensional analysis and three-dimensional numerical simulation results. DETAILED DESCRIPTION

[0016] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions of the embodiments of the present application with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the described embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0017] Unless otherwise defined, technical terms or scientific terms used in the present application shall have the common meaning understood by one of ordinary skill in the art to which the present application pertains. The terms "first", "second", and similar terms used in the present application do not denote any order, quantity, or importance, but are used to distinguish different components. Similarly, the terms "one", "a", or "the" and similar terms do not denote a quantity restriction, but mean that at least one exists. The terms "include", "comprise", and similar terms mean that the elements or objects before the terms encompass the elements or objects listed after the terms and their equivalents, and do not exclude other elements or objects. The terms "connect" or "connected" and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect.

[0018] How to quickly and accurately calculate the thrust and power of the electrically driven ducted fan is the key to evaluating the propulsion performance of the electrically driven ducted fan. For the parameterized model of the electrically driven ducted fan, the flow performance indicators and geometric sizes of the electrically driven ducted fan at the design point are known, and one-dimensional positive problem thrust characteristic analysis is carried out to calculate the thrust generated by the electrically driven ducted fan and the power consumed. The electrically driven ducted fan aerodynamic-propulsion coupling positive problem analysis method is as shown in Figure 1 .

[0019] The specific content is as follows: As Figures 1 to 3 shown, a performance evaluation method of an electrically driven ducted fan based on one-dimensional positive problem analysis, the performance evaluation parameters of the electrically driven ducted fan including ducted fan torque and ducted fan force efficiency, the method comprising: S1, four calculation stations are arranged along the streamline in the control body of the electrically driven ducted fan, and the parameterized model of the electrically driven ducted fan is obtained; S2, according to the parameterized model of the electrically driven ducted fan, the total temperature and total pressure of the outlet airflow and the rim power of the ducted fan are obtained; S3, according to the total temperature and total pressure of the outlet airflow and the convergent-divergent nozzle flow equation, the absolute speed of the nozzle outlet airflow is obtained; S4, according to the absolute velocity of the gas flow at the nozzle outlet, combined with the outlet Mach number and the continuity equation of the electric ducted fan mass flow, the ducted fan thrust is obtained; the ducted fan force efficiency is obtained according to the ducted fan thrust; the ducted fan speed is obtained according to the ducted fan rim power, and the ducted fan torque is obtained based on the ducted fan speed combined with the ducted fan power.

[0020] In a specific embodiment, S1, four calculation stations are arranged along the streamline in the electric ducted fan control body to obtain the electric ducted fan parameterized model, including: Four calculation stations are arranged along the streamline in the electric ducted fan control body, including 1-1 cross section, 2-2 cross section, 3-3 cross section and 4-4 cross section; Among them, 1-1 cross section is the inlet cross section of electric ducted fan; 2-2 cross section is the leading edge cross section of the electric ducted fan; 3-3 cross section is the outlet guide vane trailing edge cross section of the electric ducted fan; 4-4 cross section is the nozzle outlet cross section of the electric ducted fan; 0-0 cross section is located in front of the electric ducted fan without disturbance infinitely far away.

[0021] In addition, the airflow is set as steady flow, the flow loss in the inlet and nozzle is defined as 0, and the airflow is assumed to expand isentropically in the convergent nozzle, which specifically includes: Assuming that the airflow is steady, ignoring the flow loss in the inlet and nozzle, and assuming that the airflow expands isentropically in the convergent nozzle, , The airflow reaches complete expansion at the nozzle outlet cross section 4-4, and the gas static pressure is equal to the atmospheric environment back pressure, that is .

[0022] On the basis of the above assumptions, the flow control equation and the aerodynamic thermal equation are solved to form the electric ducted fan propulsion performance design index and flow parameter conversion method.

[0023] The electric ducted fan mass flow is calculated by the continuity equation: ; Among them, ; In the formula, The mass flow of the characteristic cross section i-i is , The stagnation pressure and temperature of the i-i cross section are respectively The flow function of the i-i cross section is The area of the i-i cross section through which the airflow passes is The included angle between the airflow flow direction and the axial direction is is the gas constant, with a value of 287.023, in units of... ; For the specific heat ratio of gases, the specific heat ratio is given by the air flowing through the electrically driven ducted fan. .then, ,unit .

[0024] The thrust generated by an electric ducted fan can be calculated using the momentum theorem, as shown in the following formula: ; In the formula, Thrust, unit: N; The absolute velocity of the airflow at the nozzle exit section 4-4 is expressed in m / s. The value of the cosine of the angle between the absolute velocity of the airflow at section 4-4 and the axis; The velocity of the incoming airflow from the electric ducted fan is the same as the flight speed of the aircraft, measured in m / s.

[0025] Calculate the power consumption of an electric ducted fan using aerodynamic thermodynamic equations: ; In the formula, The work done by the blade rim is expressed in kJ / kg. Total pressure ratio; It is isentropic efficiency.

[0026] In one specific implementation, S2, based on the parameterized model of the electric ducted fan, the total temperature and pressure of the outlet airflow and the ducted fan flange work are obtained, including: S201. Based on the isentropic efficiency expression, the total temperature at the trailing edge section of the exit guide vane is obtained. The formula includes formula (1): (1) in, For isentropic efficiency, For the total pressure ratio at the design point, The total temperature at section 1-1; The total temperature at section 3-3; k is the specific heat ratio of the gas; S202, Based on the total pressure ratio at the design point The total pressure of the airflow at section 3-3 was obtained. ; S203, the total temperature and pressure of the outlet gas flow are the same as those at section 4-4, based on the isentropic expansion of the gas flow in the nozzle, T3 =T4 P3 =P4 .

[0027] The formula for calculating the work of the ducted fan wheel rim S2 includes (2): (2) Wherein, L u is the work of the ducted fan wheel rim, and R is the gas constant.

[0028] In S201 to S203, the total temperature of the inlet T1, the total pressure ratio of the design point, and the isentropic efficiency are known. The total temperature of the airflow after being compressed by the moving blade can be calculated by formula (2). The total pressure of the airflow at the 3-3 section can be calculated by the total pressure ratio of the design point of the electrically driven ducted fan.

[0029] In a specific embodiment, S3, the absolute velocity of the airflow at the outlet of the nozzle is obtained based on the total temperature and total pressure of the outlet airflow and the converging-diverging nozzle flow equation, including: After the airflow enters the nozzle, it undergoes isentropic expansion, and the absolute velocity of the airflow at the outlet of the nozzle can be calculated according to the converging-diverging nozzle flow equation.

[0030] The formula for calculating the absolute velocity of the airflow at the outlet of the nozzle C 4is is formula (3): (3) P4 is the static pressure of the 4-4 section, P4=P0, and P0 is the static pressure of the 0-0 section.

[0031] In a specific embodiment, S4, the ducted fan thrust is obtained based on the absolute velocity of the airflow at the outlet of the nozzle, the outlet Mach number, and the continuity equation of the mass flow of the electrically driven ducted fan; the ducted fan force efficiency is obtained based on the ducted fan thrust; the ducted fan rotational speed is obtained based on the ducted fan wheel rim work; the ducted fan torque is obtained based on the ducted fan rotational speed and the ducted fan power, including: At this time, the total temperature, total pressure, and static pressure of the airflow at the 4-4 section of the electrically driven ducted fan are known, and the static temperature T4 of the airflow at the outlet of the nozzle can be calculated by the total parameter equation of the airflow, and the Mach number , of the airflow at the outlet of the nozzle can be calculated.

[0032] Specifically, it includes: S401, the outlet flow coefficient is calculated based on the outlet Mach number, and the calculation formula of the outlet flow coefficient is formula (4): (4) Ma4 is the outlet Mach number, and λ4 is the outlet flow coefficient. ​​​S402, obtaining an outlet flow function based on the outlet flow coefficient; The formula of the outlet flow function is formula (5): ; (5) Wherein, q (λ4) is the outlet flow function; S403, the outlet flow function is brought into the continuity equation of the electric drive duct fan mass flow, and the duct fan thrust is obtained.

[0033] The formula of the duct fan thrust is formula (6): ; (6) Wherein, F fan is the duct fan thrust, α4 is the angle between the airflow flow direction at 4-4 section and the axial direction, V0 is the incoming flow speed of the electric drive duct fan; Wherein, ; Wherein, ; Wherein, m4 is the mass flow at 4-4 section, and A4 is the area through which the airflow passes at 4-4 section.

[0034] In addition, the duct fan force efficiency obtained from the duct fan thrust in S4 includes: S404, calculating the duct fan power P fan , which is formula (7): ; (7) S405, obtaining the duct fan force efficiency based on the duct fan power and the duct fan thrust, and the formula of the duct fan force efficiency is formula (8): ; (8) g is the acceleration of gravity.

[0035] In addition, the duct fan wheel rim power is obtained from the duct fan speed, and the formula for calculating the duct fan torque T based on the duct fan speed combined with the duct fan power is formula (9): ; (9) Wherein, ; Wherein, , r ref is the reference radius of the electric drive duct fan, r hub is the hub radius of the electric drive duct fan hub, r shr is the casing radius, is the load coefficient.

[0036] As Figure 3The flow parameters of the electric ducted fan under any operating condition are known, and the one-dimensional aerodynamic-propulsion coupled direct problem analysis method can be used to calculate the propulsion performance. The three-dimensional numerical simulation of the rotational speed, total pressure ratio, and efficiency is given as the known quantity, the actual geometric size of the electric ducted fan is given, the one-dimensional direct problem analysis method is input, and the characteristic curve of the electric ducted fan is obtained.

[0037] From Figure 3 (a) and 3(b), the one-dimensional analysis and the three-dimensional numerical simulation results are parallel in the outlet axial velocity, mass flow, thrust, and power characteristic curves, and the change trend is consistent with the rotational speed, and each parameter increases with the increase of the rotational speed. From the observation of Figure 3 (b), it is found that under the same rotational speed, the thrust calculated by the one-dimensional analysis is slightly larger than the ground test result, and the relative deviation is within 4%.

[0038] The electric ducted fan force efficiency obtained by the two methods is calculated, respectively, as shown in Figure 3 (c). In the ground state, when the flight speed is 0, the duct force efficiency decreases with the increase of the rotational speed. From formula 10 in section 2.3, the electric ducted fan force efficiency is inversely proportional to the total pressure ratio, and the electric ducted fan total pressure ratio increases with the increase of the rotational speed. Further analysis shows that the reason for the decrease of the electric ducted fan force efficiency is that the increase of the electric ducted fan total pressure ratio causes the increase of the outlet axial velocity, which in turn leads to the increase of the kinetic energy carried by the outlet airflow, i.e. the residual velocity loss increases. In order to improve the propulsion performance of the electric ducted fan, appropriate design point parameters should be selected in the design stage, especially the design point total pressure ratio should not be too high.

[0039] The selection of the electric ducted fan total pressure ratio is also limited by two other factors. On the one hand, the electric ducted fan total pressure ratio cannot be too low, so that the outlet axial airflow velocity is less than the flight speed, at which the electric ducted fan cannot produce effective thrust in the flight direction. On the other hand, with the decrease of the electric ducted fan total pressure ratio, the thrust that can be generated by the electric ducted fan per unit flow area decreases, in order to meet the requirement of the aircraft thrust, the size of the electric ducted fan flow passage or the number of electric ducted fans must be increased, which affects the structure and layout design of the aircraft.

[0040] The direct problem analysis method realizes the paradigm conversion of the electric ducted fan flow parameters to the propulsion characteristic parameters, the analysis and calculation results are consistent with the change trend of the three-dimensional numerical simulation and the ground test results, the relative deviation of the thrust and the test conversion result is effectively controlled within 5%. The relative deviation of the force efficiency and the three-dimensional numerical simulation result is less than 1.5%. In addition, this method is based on one-dimensional direct problem analysis, which can quickly calculate the electric ducted fan force efficiency and torque.

[0041] The following points need to be explained: (1) The drawings of the embodiments of the present application only relate to the structures involved in the embodiments of the present application, and other structures can be referred to the general design.

[0042] (2) In the drawings used to describe the embodiments of the present application, the thickness of a layer or region is exaggerated or reduced for clarity, i.e., the drawings are not drawn according to the actual scale. It can be understood that when an element such as a layer, film, region or substrate is referred to as being "on" or "under" another element, it can be "directly" on or under the other element or there can be an intermediate element.

[0043] (3) In the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other to obtain new embodiments.

[0044] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for performance evaluation of an electrically driven ducted fan based on one-dimensional direct problem analysis, characterized in that, Performance evaluation parameters of the electrically-driven ducted fan include ducted fan torque and ducted fan force efficiency, and the method comprises: S1, four calculation stations are arranged along the flow line in the electrically-driven ducted fan control body to obtain an electrically-driven ducted fan parameterization model; S2, according to the electrically-driven ducted fan parameterization model, outlet gas total temperature and total pressure and ducted fan hub work are obtained; S3, according to the outlet gas total temperature and total pressure and the converging nozzle flow equation, the absolute velocity of the gas flow at the nozzle outlet is obtained; S4, according to the absolute velocity of the gas flow at the nozzle outlet, the outlet Mach number and the continuity equation of the electrically-driven ducted fan mass flow, the ducted fan thrust is obtained; the ducted fan force efficiency is obtained according to the ducted fan thrust; the ducted fan rotational speed is obtained according to the ducted fan hub work, and the ducted fan torque is obtained based on the ducted fan rotational speed and the ducted fan power.

2. The method for performance evaluation of an electrically-driven ducted fan based on one-dimensional direct problem analysis according to claim 1, characterized in that, The four calculation stations in S1 include: The four calculation stations include 1-1 section, 2-2 section, 3-3 section and 4-4 section; The 1-1 section is the inlet section of the electrically-driven ducted fan; The 2-2 section is the leading edge section of the electrically-driven ducted fan; The 3-3 section is the outlet guide vane trailing edge section of the electrically-driven ducted fan; The 4-4 section is the nozzle outlet section of the electrically-driven ducted fan; The 0-0 section is located in front of the electrically-driven ducted fan.

3. The method for performance evaluation of an electrically-driven ducted fan based on one-dimensional direct problem analysis according to claim 2, characterized in that, The electrically-driven ducted fan parameterization model in S1 includes: The gas flow is set as steady flow, the flow loss in the inlet duct and the nozzle is defined as 0, and the gas flow is isentropically expanded in the converging nozzle.

4. The method for performance evaluation of an electrically-driven ducted fan based on one-dimensional direct problem analysis according to claim 3, characterized in that, The outlet gas total temperature and total pressure obtained according to the electrically-driven ducted fan parameterization model in S2 include: S201、According to the isentropic efficiency expression, the total temperature at the outlet guide vane tail edge section is obtained The formula includes formula (1): ；（1） wherein, is the isentropic efficiency, is the design point total pressure ratio, is the total temperature at the 1-1 cross section; is the total temperature at the 3-3 cross section; k is the gas specific heat ratio; S202、According to the design point total pressure ratio , get 3-3 cross-section airflow total pressure ; S203, the total temperature and total pressure at the 4-4 section of the outlet airflow, based on the isentropic expansion of the airflow in the nozzle, T3 =T4 , P3 =P4 .

5. The method for performance evaluation of an electrically-driven ducted fan based on one-dimensional direct problem analysis according to claim 4, characterized in that, The ducted fan hub work calculation formula in S2 includes formula (2): ；（2） where L u is the work of the fan wheel; R is the gas constant.

6. The method for performance evaluation of an electrically-driven ducted fan based on one-dimensional direct problem analysis according to claim 5, characterized in that, The absolute velocity C of the gas flow at the outlet of the nozzle is obtained by combining the total temperature and total pressure of the outlet gas flow in S3 with the flow equation of the converging-diverging nozzle 4is The formula is formula (3): ；（3） P4 is the gas static pressure at the 4-4 section, P4=P0, and P0 is the gas static pressure at the 0-0 section.

7. The method for performance evaluation of an electrically-driven ducted fan based on one-dimensional direct problem analysis according to claim 6, characterized in that, The ducted fan thrust obtained according to the absolute velocity of the gas flow at the nozzle outlet in S4 includes: S401, the outlet flow coefficient is calculated based on the outlet Mach number, and the calculation formula of the outlet flow coefficient is formula (4): ；（4） Ma4 is the outlet Mach number, and λ4 is the outlet flow coefficient; S402, the outlet flow function is obtained based on the outlet flow coefficient; S403, the outlet flow function is brought into the continuity equation of the electrically-driven ducted fan mass flow to obtain the ducted fan thrust.

8. The method for performance evaluation of an electrically-driven ducted fan based on one-dimensional direct problem analysis according to claim 7, characterized in that, The formula for obtaining the outlet flow function based on the outlet flow coefficient in S402 is formula (5): ；（5） Wherein, q(λ4) is the outlet flow function; The formula for the ducted fan thrust in S403 is formula (6): ；（6） where F fan is the ducted fan thrust, a4 is the angle between the airflow direction at the 4-4 section and the axial direction, and V0 is the incoming airflow speed of the electrically driven ducted fan. wherein ; wherein ; Wherein, m4 is the mass flow at the 4-4 section, and A4 is the area through which the gas flow passes at the 4-4 section.

9. The method for performance evaluation of an electrically-driven ducted fan based on one-dimensional direct problem analysis according to claim 8, characterized in that, The ducted fan force efficiency obtained according to the ducted fan thrust in S4 includes: S404、calculate the bypass fan power P fan The bypass fan power P is formula (7): ；（7） S405, the ducted fan force efficiency is obtained based on the ducted fan power and the ducted fan thrust, and the formula of the ducted fan force efficiency is formula (8): ；（8） g is the acceleration of gravity.

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