A flexible variable nacelle control method considering multi-state power matching requirements of electric propulsion ducted fans

Abstract

This invention provides a flexible variable casing control method that considers the multi-state power matching requirements of electric propulsion ducted fans, relating to the field of aerospace electric propulsion technology. It includes: receiving the inflow conditions, thrust requirements, and power constraints of the electric propulsion ducted fan; determining the throat radius of a flexible variable casing arranged in the flow channel downstream of the stator of the electric propulsion ducted fan; and changing the profile of the flexible variable casing by adjusting the pressure difference inside and outside the casing to achieve control over the operating conditions and power of the electric propulsion ducted fan, thereby meeting the multi-state power matching requirements of the electric propulsion ducted fan. This invention solves the problems of complex structure and difficult operation and control of existing nozzle adjustment schemes, and can effectively improve the comprehensive multi-state performance of electric propulsion ducted fans.

Description

Technical Field

[0001] This invention relates to the field of aviation electric propulsion technology, and specifically to a flexible variable casing control method that takes into account the multi-state power matching requirements of electric propulsion ducted fans. Background Technology

[0002] Driven by the development of all-electric / hybrid aircraft and new energy aircraft, electric propulsion ducted fans have become one of the mainstream propulsion devices in distributed propulsion systems and have received significant attention in recent years. Compared to propellers, electric propulsion ducted fans benefit from the airflow capture and organization effect of the duct lip, allowing them to provide high-quality air intake to the rotor and generate greater thrust or lift than propellers of the same diameter at the same input power. Simultaneously, the enclosed duct of the electric propulsion ducted fan provides physical safety protection and limits noise levels, thus aligning with the future development goals of green, efficient, and safe aviation.

[0003] The thrust ratio of high-speed electric ducted fans used in horizontal takeoff and landing aircraft to that in the ground and cruise conditions will exceed 7, even more so than the thrust ratio of electric ducted fans used in vertical takeoff and landing aircraft to that in the vertical hover and horizontal cruise conditions, which exceeds 12. This is far higher than the fan / compressor state in traditional turbofan engines. The excessive thrust difference may cause electric ducted fans to operate under extreme conditions such as deep stagnation and near stall during the ground, climb, cruise, or hover phases, affecting the matching efficiency of electric ducted fans. Electric ducted fans face the problem of matching thrust, power, and aerodynamic performance under multiple conditions.

[0004] To achieve multi-state power matching, electric propulsion ducted fans need to achieve flow matching under multiple states through geometric adjustments and other means. Compared to propellers, electric propulsion ducted fan rotors have higher aerodynamic loads and speeds, and are smaller in size and volume, making it difficult to implement propeller-like "variable pitch" technology on small-sized, high-load electric propulsion ducted fan rotors.

[0005] Therefore, electric propulsion ducted fans typically employ adjustable nozzles to achieve multi-state matching. For example, the use of "variable nozzles" effectively improves the aerodynamic efficiency of the ducted fan during cruise and hovering. This measure requires complex adjustment mechanisms and structural designs to achieve nozzle adjustment, including sealing structures, motion mechanisms, adjustment vanes, and hydraulic actuation systems. The structural design and high-precision, robust adjustment and control are challenging and costly, and also significantly increase the system's structural weight, which is detrimental to overall performance. Summary of the Invention

[0006] In view of this, the embodiments of this application provide a flexible variable casing control method that takes into account the multi-state power matching requirements of electric propulsion ducted fans. By actively and intelligently controlling the profile of the flexible variable casing under different states, the effective airflow and aerodynamic state adjustment of the electric propulsion ducted fan are realized, thereby achieving the purpose of multi-state power matching of the electric propulsion ducted fan.

[0007] This application provides the following technical solution: a flexible variable casing control method that takes into account the multi-state power matching requirements of electric propulsion ducted fans, including:

[0008] Obtain the inflow conditions of the electric propulsion ducted fan, wherein the inflow conditions include: the total inflow pressure p t0 Static pressure p0, total temperature T t0 Mach number Ma0 signal;

[0009] Based on the incoming flow conditions and the overall required thrust F, determine the constraint power P of the electric propulsion ducted fan under the current state;

[0010] The operating conditions of the electric propulsion ducted fan are determined based on the required thrust F and the constrained power P, and the required area and required radius R4 of the flexible variable casing throat are determined.

[0011] Obtain the static pressure p4 signal of the upstream channel of the flexible variable casing, adjust the static pressure pa of the outer cavity of the flexible variable casing, and determine the actual radius R41 of the throat of the flexible variable casing based on the static pressure p4 signal of the upstream channel and the static pressure pa of the outer cavity.

[0012] Determine whether the actual radius R41 of the flexible variable casing throat is equal to the required radius R4 under the current state. If yes, calculate the actual power P1 of the electric propulsion ducted fan under the current state. If no, reacquire the static pressure p4 signal of the upstream casing channel of the flexible variable casing and adjust the static pressure pa of the outer cavity of the flexible variable casing until the actual radius R41 of the flexible variable casing throat is equal to the required radius R4.

[0013] Determine whether the actual power P1 of the electric propulsion ducted fan in the current state is less than or equal to the constraint power P. If yes, fix the static pressure pa of the flexible variable casing outer cavity, and the flexible variable casing in the current state is adjusted. If no, redetermine the operating conditions and required radius R4 of the electric propulsion ducted fan, and readjust the flexible variable casing profile so that the actual radius R41 of the throat is equal to the required radius R4. Calculate the actual power P1 again until the actual power P1 is less than or equal to the constraint power P, and the flexible variable casing adjustment is completed. After the adjustment is completed, output the geometry of the flexible variable casing profile, the actual power of the electric propulsion ducted fan, and the actual thrust.

[0014] Preferably, the state of the electric propulsion ducted fan changes, i.e., the total incoming pressure p t0Static pressure p0, total temperature T t0 As the Mach number Ma0, the required thrust F, and the constraint power P change, the power matching of the electric propulsion ducted fan under the new state can be achieved by following the steps described above.

[0015] This invention provides a flexible variable casing control method that takes into account the multi-state power matching requirements of electric propulsion ducted fans. Based on receiving the incoming flow parameters of the electric propulsion ducted fan and the static pressure of the upstream inner channel of the flexible variable casing, the method adjusts the pressure of the outer cavity of the flexible variable casing to change the profile of the flexible variable casing, thereby changing the effective flow area, ducted fan pressure ratio and efficiency of the electric propulsion ducted fan. This achieves multi-state power matching of the electric propulsion ducted fan, solving the problems of complex structure, high precision and high robust modulation difficulty of existing nozzle adjustment methods.

[0016] According to one embodiment of the present invention, the electric propulsion ducted fan includes: a duct body, a flexible variable casing, a flexible variable casing outer cavity, a suction pipe, a control valve, a vacuum pump, a rotor, a stator, an intake cone, a drive motor, an exhaust cone, and an outlet total temperature-total pressure composite comb probe.

[0017] The duct body is located around the blades of the electric propulsion ducted fan and mainly plays the roles of rectification, noise reduction, blade protection, load bearing, and flow state regulation.

[0018] The rotor is directly mechanically connected to the drive motor. By rotating, it draws airflow into the electric propulsion ducted fan and performs work to pressurize the airflow.

[0019] The stator, located downstream of the rotor, mainly serves to guide flow and bear force.

[0020] The intake cone, connected to the rotor, mainly serves to rectify airflow and protect the equipment inside the hub cavity.

[0021] The drive motor is built into the stator flow channel and is the power source for the electric propulsion ducted fan. It drives the rotor to rotate through the output shaft.

[0022] The exhaust cone, located downstream of the drive motor, serves a rectifier function.

[0023] Preferably, the outlet of the electric propulsion ducted fan is equipped with a composite comb-shaped probe for total temperature and total pressure, which is fixed by an external bracket and used to measure the total temperature T at the outlet of the electric propulsion ducted fan. t5 Total pressure p t5 The static pressure p5 and flow velocity V5; wherein, the outlet total temperature-total pressure composite comb probe is a radial 5-point comb probe, distributed in an equal toroidal pattern in the radial direction; the total pressure probe of the outlet total temperature-total pressure composite comb probe is a three-hole probe, and the outlet total pressure p of the electric propulsion ducted fan is obtained by processing and calculating the data measured by the three pressure measuring holes. t5Static pressure p5, flow velocity V5;

[0024] Preferably, the duct body has a static pressure measuring hole arranged in the upstream casing of the flexible variable casing for measuring the static pressure p4 in the upstream casing of the flexible variable casing.

[0025] Preferably, the flexible variable casing is installed on the inner flow channel downstream of the stator of the duct body, and the throat of the flexible variable casing is the position where the radius of the flexible variable casing is the smallest.

[0026] Preferably, the flexible variable casing is made of a pressure differential driven intelligent composite material, so that the internal flow channel profile of the flexible variable casing changes under pressure differential drive and is a continuous and smooth sine function;

[0027] Preferably, the position with the smallest radius of the flexible variable casing is the throat of the flexible variable casing, and the variation range of the actual radius R41 of the throat of the flexible variable casing is: 0.90Rs≤R41≤1.02Rs, where Rs is the radius of the throat of the flexible variable casing when the pressure difference between the inside and outside of the flexible variable casing is zero.

[0028] Preferably, the axial length L of the flexible variable casing is in the range of: 0.10Rs≤L≤0.40Rs;

[0029] Preferably, the outer side of the flexible variable casing is an outer cavity, which is connected to the suction pipe and the vacuum pump. The suction pipe is equipped with a control valve. By adjusting the opening of the control valve, the static pressure pa of the outer cavity of the flexible variable casing is changed, thereby regulating the internal and external pressure difference of the flexible variable casing, changing the surface geometry of the flexible variable casing and the actual radius R41 of the throat of the flexible variable casing, and realizing the regulation of the operating conditions and power of the electric propulsion ducted fan.

[0030] Preferably, the actual radius R41 of the flexible variable casing throat is related to the static pressure pa of the flexible variable casing outer cavity, the static pressure p4 of the upstream casing inner channel of the flexible variable casing, and the material's own performance parameters, namely:

[0031] (1)

[0032] Optionally, in the method, the total incoming pressure p of the electric propulsion ducted fan... t0 Static pressure p0, total temperature T t0 The Mach number (Ma0) signal is emitted by the airborne equipment.

[0033] Preferably, the required thrust F and the constraint power P are determined based on the incoming flow state and overall requirements;

[0034] Optionally, the total pressure ratio of the electric propulsion ducted fan for:

[0035] (2)

[0036] Optionally, the thermal efficiency of the electric propulsion ducted fan... for:

[0037] (3)

[0038] Where k is the inlet adiabatic coefficient, which is taken as 1.4;

[0039] Optionally, the actual power P1 of the electric propulsion ducted fan is calculated by the following formula:

[0040] (4)

[0041] Where m is the mass flow rate of the electric propulsion ducted fan, in kg / s; c p T is the specific heat capacity of air, expressed in J / (kg·K); t5 The total outlet temperature of the electric propulsion ducted fan, in Kelvin (K), is measured by a composite comb probe measuring the total outlet temperature and total pressure (T). t0 The total incoming temperature is expressed in Kelvin (K).

[0042] Optionally, the actual thrust F1 of the electric propulsion ducted fan is calculated by the following formula:

[0043] (5)

[0044] Where m is the mass flow rate of the electric propulsion ducted fan, in kg / s; V0 is the incoming flow velocity, in m / s, calculated from the incoming flow Ma and ambient atmospheric parameters; V5 is the outlet velocity of the electric propulsion ducted fan, in m / s, calculated from the outlet total temperature-total pressure composite comb probe measurement data; and A5 is the outlet area of ​​the electric propulsion ducted fan, in m². 2 p5 is the static pressure at the outlet of the electric propulsion ducted fan, in Pa, calculated from the total temperature-total pressure composite comb probe measurement data at the outlet; p0 is the incoming static pressure, in Pa, obtained from ambient atmospheric parameters.

[0045] Preferably, the total outlet temperature T of the electric propulsion ducted fan is... t5 The outlet speed V5 and outlet static pressure p5 are related to the ducted fan's operating status, namely the pressure ratio and adiabatic efficiency.

[0046] Preferably, adjusting the actual radius R41 of the flexible variable casing throat can change the mass flow rate m and pressure ratio of the electric propulsion ducted fan. Insulation efficiency This further affects the actual power and actual thrust of the electric propulsion ducted fan, namely:

[0047] (6)

[0048] (7)

[0049] Where n is the rotational speed of the electric propulsion ducted fan, in r / min.

[0050] Compared with the prior art, the beneficial effects that can be achieved by at least one of the above-mentioned technical solutions adopted in the embodiments of this specification include at least the following: In the embodiments of this invention, a flexible variable casing is arranged in the flow channel of the downstream duct of the electric propulsion ducted fan stator. By adjusting the static pressure of the outer cavity of the flexible variable casing, the profile and throat radius of the flexible variable casing can be adjusted, thereby changing the mass flow rate, pressure ratio, and adiabatic efficiency of the electric drive ducted fan, and thus achieving the control of the power and thrust of the electric drive ducted fan, ultimately meeting the multi-state power matching requirements of the electric propulsion ducted fan; it is beneficial to improve the aerodynamic performance and multi-condition adaptability of the electric propulsion ducted fan, reduce the complexity of the additional system and the difficulty of operation and control, and provide technical support for the power matching of the electric propulsion ducted fan in multiple states such as ground takeoff, climb, cruise, and hovering. Attached Figure Description

[0051] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0052] Figure 1 This is a schematic diagram of a flexible variable casing control method for electric propulsion ducted fans that takes into account the multi-state power matching requirements of electric propulsion ducted fans according to the present invention.

[0053] Figure 2 This is a schematic diagram of an electric propulsion ducted fan with a flexible variable casing that takes into account the multi-state power matching requirements of the electric propulsion ducted fan in an embodiment of the present invention.

[0054] Figure 3 This is a schematic diagram of the flexible variable casing structure in an embodiment of the present invention;

[0055] Figure 4 The model used for numerical simulation in the embodiments of the present invention;

[0056] In the diagram: 1. Ductwork; 11. Flexible variable casing; 111. Flexible variable casing throat; 12. Flexible variable casing outer cavity; 13. Suction pipe; 131. Control valve; 14. Vacuum pump; 15. Static pressure measuring hole; 2. Rotor; 3. Stator; 4. Inlet cone; 5. Drive motor; 6. Exhaust cone; 7. Outlet total temperature-total pressure composite comb probe. Detailed Implementation

[0057] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0058] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0059] The flow chart of a flexible variable casing control method for electric propulsion ducted fans that takes into account multi-state power matching requirements is as follows: Figure 1 As shown, an implementation of an electric propulsion ducted fan applying the flexible variable casing method of the present invention is, for example... Figure 2 As shown, the structural schematic diagram and key geometric parameters of the flexible variable casing of this invention are as follows: Figure 3 As shown.

[0060] Specifically, such as Figure 1 As shown, the process of the flexible variable casing control method for the electric propulsion ducted fan of the present invention includes:

[0061] S101: Receives the total incoming pressure p of the electric propulsion ducted fan. t0 Static pressure p0, total temperature T t0 The Mach number Ma0 signal, specifically, the total incoming pressure p. t0 Static pressure p0, total temperature T t0 The Mach number (Ma0) signal is emitted by airborne equipment and is related to the actual operating / flight environment of the electric propulsion ducted fan.

[0062] S102: Based on the incoming flow conditions and the overall required thrust F, determine the constraint power P of the electric propulsion ducted fan under this condition. Specifically, the required thrust F and constraint power P of the electric propulsion ducted fan under this incoming flow condition are determined by the overall aircraft and power system based on the aircraft weight, lift-to-drag ratio, safety margin, etc.

[0063] S103: Determine the operating conditions of the electric propulsion ducted fan based on the required thrust F and constrained power P, and further determine the required area and radius R4 of the flexible variable casing throat. Specifically, the operating conditions of the electric propulsion ducted fan refer to the mass flow rate m and pressure ratio. and insulation efficiency The mass flow rate m and pressure ratio of the electric propulsion ducted fan in this state, satisfying the thrust F and constraint power P, are determined according to the following formulas. and insulation efficiency :

[0064] (8)

[0065] (9)

[0066] (10)

[0067] (11)

[0068] (12)

[0069] (13)

[0070] (14)

[0071] In the formula, P represents the constrained power of the electric propulsion ducted fan, in W; m represents the mass flow rate through the electric propulsion ducted fan, in kg / s; c p T represents the specific heat capacity of air, expressed in J / (kg·K); t0 and T t5 These represent the total incoming air temperature and the total outlet air temperature of the electric propulsion ducted fan, respectively, in K. The total pressure ratio of the electric propulsion ducted fan is the ratio of the total pressure at the outlet of the electric propulsion ducted fan to the total pressure of the incoming flow. The values ​​represent the adiabatic efficiency of the electric propulsion ducted fan; k represents the inlet adiabatic coefficient, taken as 1.4; V0 and V5 represent the inlet and outlet airflow velocities of the electric propulsion ducted fan, respectively, in m / s; p0 and p5 represent the inlet and outlet static pressures of the electric propulsion ducted fan, respectively, in Pa; and A5 represents the outlet area of ​​the electric propulsion ducted fan, in m². 2 λ5 represents the velocity factor of the airflow at the outlet of the electric propulsion ducted fan; q(λ5) represents the dimensionless dense flow of the airflow at the outlet of the electric propulsion ducted fan; R represents the gas constant, with a value of 287.06 J / (kg·K).

[0072] Specifically, the flexible variable casing is installed on the inner flow channel downstream of the stator of the ducted body. The throat of the flexible variable casing is the position with the smallest radius of the flexible variable casing. By adjusting the area of ​​the flexible variable casing throat (i.e., the throat radius R4), the mass flow rate m and pressure ratio of the electric propulsion ducted fan under the same incoming flow conditions and speed can be controlled. and insulation efficiency Specifically, based on the determined conditions under which the electric propulsion ducted fan satisfies the thrust F and the constraint power P, the mass flow rate m and pressure ratio... and insulation efficiency The required area and radius R4 of the flexible variable casing throat were initially determined.

[0073] S104: Receive the static pressure p4 signal of the upstream channel of the flexible variable housing, and adjust the static pressure pa of the outer cavity of the flexible variable housing. Specifically, the static pressure p4 of the upstream channel of the flexible variable housing is measured by a static pressure measuring hole arranged in the channel of the housing. The axial distance between the static pressure measuring hole and the flexible variable housing should be as small as possible while meeting the requirements of structural strength and assembly safety, and should not exceed 30% of the axial length of the flexible variable housing. Specifically, the outer side of the flexible variable housing is the outer cavity, which is connected to the suction pipe and the vacuum pump. The suction pipe is equipped with a control valve, which, together with the vacuum pump, can realize the regulation of the static pressure pa of the outer cavity of the flexible variable housing.

[0074] S105: The flexible variable casing changes its profile under the pressure difference between the inner and outer walls. The actual radius of the throat of the flexible variable casing is R41. Specifically, the flexible variable casing adopts a pressure difference-driven intelligent composite material. The material geometry can change under pressure difference. Under pressure difference, the inner flow channel profile of the flexible variable casing is a continuous and smooth sine function. Specifically, the actual radius R41 of the throat of the flexible variable casing is related to the static pressure pa of the outer cavity, the static pressure p4 of the upstream inner flow channel of the flexible variable casing, and the material's own performance parameters (such as material composition, micro-geometric parameters of porous materials, etc.), i.e., R41=f1(pa, p4, material parameters). Specifically, the variation range of the actual radius R41 of the throat of the flexible variable casing is: 0.90Rs≤R41≤1.02Rs, where Rs is the radius at the throat position when the pressure difference between the inner and outer walls of the flexible variable casing is zero. The value range of the axial length L of the flexible variable casing is: 0.10Rs≤L≤0.40Rs.

[0075] S106: Determine whether the actual radius R41 of the flexible variable casing throat is equal to the required radius R4 in this state. If yes, calculate the power P1 of the electric propulsion ducted fan in this state. If no, re-receive the static pressure p4 signal of the upstream casing channel of the flexible variable casing and adjust the static pressure pa of the outer cavity of the flexible variable casing until the actual radius R41 of the flexible variable casing throat is equal to the required radius R4. Specifically, if the actual radius R41 of the flexible variable casing throat is less than the required radius R4, receive the new static pressure p4 of the casing channel, increase the static pressure pa of the outer cavity of the flexible variable casing by increasing the opening of the control valve, and then reduce the pressure difference p4-pa between the inside and outside of the flexible variable casing, thereby increasing the throat radius of the flexible variable casing. Through feedback iteration, the expected throat radius R4 is achieved.

[0076] S107: Calculate the actual power P1 of the electric propulsion ducted fan in this state. Specifically, the actual power P1 of the electric propulsion ducted fan in this state is calculated as follows:

[0077] (15)

[0078] Specifically, the total temperature T of the electric propulsion ducted fan inlet. t0 The total temperature T of the electric propulsion ducted fan outlet airflow is related to the actual operating / flight environment of the ducted fan and is measured and received by onboard equipment. t5 The mass flow rate m of the electric propulsion ducted fan was obtained by measuring the total temperature and total pressure at the outlet using a composite comb probe.

[0079] S108: Determine whether the actual power P1 of the electric propulsion ducted fan in this state is less than or equal to the constraint power P. If yes, fix the static pressure pa of the outer cavity of the variable casing, and the flexible variable casing in this state completes the regulation. If no, redetermine the operating conditions and required radius R4 of the electric propulsion ducted fan, and then readjust the profile of the flexible variable casing so that the actual radius R41 of the throat is equal to the required radius R4. Calculate the actual power P1 again until the actual power P1 is less than or equal to the constraint power P, and the regulation of the flexible variable casing is completed. Specifically, if the actual power P1 is greater than the constraint power P, it indicates that the operating conditions of the electric propulsion ducted fan do not meet the working requirements. Based on the difference between the actual flow rate, total pressure ratio, and adiabatic efficiency of the electric propulsion ducted fan at this time and the operating conditions determined in S103, redetermine the required operating conditions of the electric propulsion ducted fan, and then proceed with S104, S105, S106, S107, and S108 in sequence until the actual power P1 is less than or equal to the constraint power P.

[0080] S109: Outputs the flexible variable casing geometry, power and thrust of the electric propulsion ducted fan. Specifically, after completing the power matching of the electric propulsion ducted fan in this state, it outputs the flexible variable casing geometry, the actual power and thrust of the electric propulsion ducted fan.

[0081] Specifically, such as Figure 2 and Figure 3 As shown, the electric propulsion ducted fan with a flexible variable casing in this embodiment includes: a duct body 1 of the electric propulsion ducted fan, a flexible variable casing 11, a flexible variable casing outer cavity 12, a suction pipe 13, a control valve 131, a vacuum pump 14, a rotor 2 of the electric propulsion ducted fan, a stator 3 of the electric propulsion ducted fan, an intake cone 4 of the electric propulsion ducted fan, a drive motor 5 of the electric propulsion ducted fan, an exhaust cone 6 of the electric propulsion ducted fan, and an outlet total temperature-total pressure composite comb probe 7 of the electric propulsion ducted fan.

[0082] Specifically, the duct 1, located around the rotor 2, mainly serves to rectify, reduce noise, protect blades, bear load, and regulate flow. In this embodiment, the air intake section of the duct 1 has an airfoil-shaped cross-section that is geometrically smooth and continuous.

[0083] Specifically, a flexible variable housing 11 is installed in the flow channel of the duct 1 downstream of the stator 3. The flexible variable housing 11 is made of pressure differential driven intelligent composite material, and its geometry can change under pressure differential drive. Under pressure differential drive, the inner flow channel profile of the flexible variable housing 11 is a continuous and smooth sine function. The position with the smallest radius of the flexible variable housing 11 is the flexible variable housing throat 111. The actual radius of the flexible variable housing throat 111 is R41: 0.90Rs≤R41≤1.02Rs, where Rs is the radius of the flexible variable housing throat 111 when the pressure difference between the inside and outside of the flexible variable housing 11 is zero. In this embodiment, Rs=160mm, 144mm≤R41≤163.2mm. The length of the flexible variable housing 11 is L: 0.10Rs≤L≤0.40Rs. In this embodiment, L=30mm. The outer side of the flexible variable housing 11 is the flexible variable housing outer cavity 12. The system is connected to the suction pipe 13 and the vacuum pump 14. The suction pipe 13 is equipped with a control valve 131, which, in conjunction with the vacuum pump 14, allows for the regulation of the static pressure pa in the outer cavity 12 of the flexible variable housing. A static pressure measuring hole 15 is arranged in the upstream flow channel of the flexible variable housing 11 to measure the static pressure p4 in the upstream flow channel of the flexible variable housing 11. By adjusting the opening of the control valve 131, the static pressure pa in the outer cavity 12 of the flexible variable housing is changed, thereby regulating the internal and external pressure difference p4-pa of the flexible variable housing 11. This, in turn, changes the profile geometry of the flexible variable housing 11 and the actual radius R41 of the throat 111 of the flexible variable housing, thus achieving the regulation of the operating conditions of the electric propulsion ducted fan. The actual radius R41 of the throat 111 of the flexible variable housing is related to the static pressure pa in the outer cavity 12 of the flexible variable housing, the static pressure p4 in the upstream flow channel of the flexible variable housing 11, and the material properties themselves. ;

[0084] Specifically, rotor 2 is directly mechanically connected to drive motor 5 via a transmission shaft. By rotating, it draws airflow into the electric propulsion ducted fan and performs work to pressurize the airflow.

[0085] Specifically, the stator 3, located downstream of the rotor 2, guides the airflow after passing through the rotor 2 and also serves as a load-bearing element; the stator 3 and the housing of the drive motor 5 are designed and manufactured as a single unit.

[0086] Specifically, the intake cone 4 is connected to the rotor 2 and rotates at the same speed, mainly serving to rectify airflow and protect the equipment inside the hub cavity;

[0087] Specifically, the drive motor 5 is built into the inner flow channel of the stator 3 and is the power source for the electric propulsion ducted fan. It drives the rotor 2 to rotate through the output shaft. Its housing and the stator 3 are designed and processed as a single unit.

[0088] Specifically, the exhaust cone 6, located downstream of the drive motor 5 and the duct body 1, serves a rectification function.

[0089] Specifically, the total temperature-total pressure composite comb probe 7 is arranged at the outlet of the duct body 1 of the electric propulsion ducted fan to measure the total temperature T at the outlet of the electric propulsion ducted fan. t5 Total pressure p t5 The static pressure is p5, and the flow velocity is V5. In this embodiment, the outlet total temperature-total pressure composite comb probe 7 is a radial 5-point comb probe, which is distributed in an equal toroidal pattern in the radial direction, that is, the toroidal patterns of adjacent measuring points are equal, and it is fixed by an external test piece bracket. The total pressure probe of the outlet total temperature-total pressure composite comb probe 7 is a three-hole probe. The outlet total temperature T of the electric propulsion ducted fan can be obtained by processing and calculating the data measured by the three pressure holes and the total temperature hole. t5 Total pressure p t5 Static pressure p5, flow velocity V5.

[0090] To verify the effectiveness of the present invention, a numerical simulation was performed on the control effect of the flexible variable casing described in the present invention. The specific implementation process is as follows:

[0091] (1) such as Figure 2 and Figure 4 As shown, a three-dimensional modeling software was used to model the aerodynamic calculation model of the electric propulsion ducted fan, which consists of duct 1, flexible variable casing 11, rotor 2, stator 3, inlet cone 4, and exhaust cone 6. The model was divided into three regions: the blade passage includes rotor 2 and stator 3; the near-field region includes duct 1, flexible variable casing 11, inlet cone 4, and exhaust cone 6; and... Figure 4 In the diagram, the far-field region is a simulated cylindrical region with a diameter 30 times the diameter (D) of rotor 2 (its radius is 15 times the diameter (D) of rotor 2, i.e., 15D), and an axial length 40 times the diameter (D) of rotor 2 (15D+25D in the diagram). The blade passage region is a single blade passage, while the near-field and far-field regions are 1 / 6 sector-shaped annulus. The radii of the flexible variable casing throat 111 are set to 160mm and 150mm, respectively.

[0092] (2) Use mesh generation software to divide the computational domain into meshes to generate a mixed structured and unstructured mesh.

[0093] (3) The three-dimensional steady Reynolds-averaged Navier-Stokes equations are solved based on the finite volume method combined with the SST k-ω turbulence model. The convection, turbulence and time terms in the equations are discretized using a high-resolution scheme. The rotational speeds of rotor 2 and intake cone 4 are given in the calculation. The inlet conditions in the far field are given the inflow velocity and ambient temperature. The outlet conditions in the far field are given the average static pressure. The far field conditions in the far field are given the ambient temperature and ambient pressure.

[0094] (4) Obtain the results of the numerical simulation and perform data processing.

[0095] As shown in Table 1, after adjusting the radius R41 of the flexible variable casing throat 111 from 160mm to 150mm, the relative change in the performance of the electric propulsion ducted fan can be seen. This embodiment of the flexible variable casing method that takes into account the multi-state power matching requirements of the electric propulsion ducted fan can achieve the change and matching of the operating conditions, performance, and power of the electric propulsion ducted fan by adjusting the radius R41 of the flexible variable casing throat 111.

[0096] Table 1. Relative Changes in the Performance of the Propulsion Ducted Fan

[0097]

[0098] Table 1 shows the converted flow rates. Calculated by the following formula:

[0099] (16)

[0100] In Table 1, the total pressure ratio The adiabatic efficiency is calculated using equation (11). Calculated by equation (12); the unit power thrust is the ratio of thrust F to power P, where thrust F is calculated by equation (9) and power P is calculated by equation (8).

[0101] As shown in Table 1, by changing the radius R41 of the flexible variable casing throat 111, specifically reducing it from 160mm to 150mm, the converted flow rate of the electric propulsion ducted fan under the same speed and incoming flow conditions decreased by 11.58%, the total pressure ratio increased by 6.60%, the adiabatic efficiency increased by 8.23%, and the thrust per unit power increased by 7.42%. Under these operating conditions, by adjusting the radius R41 of the flexible variable casing throat 111, the electric propulsion ducted fan using the flexible variable casing 11 successfully shifted its operating state from a congested condition of high flow rate, low pressure ratio, and low efficiency to a high-efficiency region of low flow rate, high pressure ratio, and high efficiency, thus increasing the thrust per unit power and achieving a match between the operating state and power of the electric propulsion ducted fan.

[0102] Thus, this invention provides a flexible variable casing control method that considers the multi-state power matching requirements of electric propulsion ducted fans. This method achieves matching between the operating conditions and power demands of the electric propulsion ducted fan. By adjusting the flexible variable casing profile to change its throat radius, the effective flow area of ​​the electric propulsion ducted fan is altered, thereby controlling the back pressure and ultimately achieving multi-state power matching. Therefore, this invention offers better operating condition adaptability and aerodynamic performance than traditional non-variable casings, and significantly reduces the complexity and weight of the additional system compared to the "nozzle adjustment" solution, providing a possible technical solution for improving the multi-state aerodynamic performance of electric propulsion ducted fans.

[0103] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A flexible variable casing control method that takes into account the multi-state power matching requirements of electric propulsion ducted fans, characterized in that, include: Obtain the inflow conditions of the electric propulsion ducted fan, wherein the inflow conditions include: the total inflow pressure p t0 Static pressure p0, total temperature T t0 Mach number Ma0 signal; Based on the incoming flow conditions and the overall required thrust F, determine the constraint power P of the electric propulsion ducted fan under the current state; The operating conditions of the electric propulsion ducted fan are determined based on the required thrust F and the constrained power P, and the required area and required radius R4 of the flexible variable casing throat are determined. Obtain the static pressure p4 signal of the upstream channel of the flexible variable casing, adjust the static pressure pa of the outer cavity of the flexible variable casing, and determine the actual radius R41 of the throat of the flexible variable casing based on the static pressure p4 signal of the upstream channel and the static pressure pa of the outer cavity. Determine whether the actual radius R41 of the flexible variable casing throat is equal to the required radius R4 under the current state. If yes, calculate the actual power P1 of the electric propulsion ducted fan under the current state. If no, reacquire the static pressure p4 signal of the upstream casing channel of the flexible variable casing and adjust the static pressure pa of the outer cavity of the flexible variable casing until the actual radius R41 of the flexible variable casing throat is equal to the required radius R4. Determine whether the actual power P1 of the electric propulsion ducted fan in the current state is less than or equal to the constraint power P. If yes, fix the static pressure pa of the flexible variable casing outer cavity, and the flexible variable casing in the current state is adjusted. If no, redetermine the operating conditions and required radius R4 of the electric propulsion ducted fan, and readjust the flexible variable casing profile so that the actual radius R41 of the throat is equal to the required radius R4. Calculate the actual power P1 again until the actual power P1 is less than or equal to the constraint power P, and the flexible variable casing adjustment is completed. After the adjustment is completed, output the geometry of the flexible variable casing profile, the actual power of the electric propulsion ducted fan, and the actual thrust.

2. The flexible variable casing control method according to claim 1, which takes into account the multi-state power matching requirements of the electric propulsion ducted fan, is characterized in that, The actual power P1 of the electric propulsion ducted fan in the current state is calculated by the following formula: Where m is the mass flow rate of the electric propulsion ducted fan, in kg / s; c p T is the specific heat capacity of air, expressed in J / (kg·K); t5 Total outlet temperature of the electric propulsion ducted fan, in K and T. t0 The total incoming temperature is expressed in Kelvin (K).

3. The flexible variable casing control method according to claim 1, which takes into account the multi-state power matching requirements of the electric propulsion ducted fan, is characterized in that, The actual thrust F1 of the electric propulsion ducted fan is calculated by the following formula: Where m is the mass flow rate of the electric propulsion ducted fan, in kg / s; V0 is the incoming flow velocity, in m / s; V5 is the outlet velocity of the electric propulsion ducted fan, in m / s; and A5 is the outlet area of ​​the electric propulsion ducted fan, in m². 2 p5 is the static pressure at the outlet of the electric propulsion ducted fan, in Pa; p0 is the incoming static pressure, in Pa.

4. The flexible variable casing control method for balancing the multi-state power matching requirements of the electric propulsion ducted fan according to claim 1, characterized in that, The electric propulsion ducted fan includes: a duct body, a flexible variable casing, a flexible variable casing outer cavity, a suction pipe, a control valve, a vacuum pump, a rotor, a stator, an intake cone, a drive motor, an exhaust cone, and an outlet total temperature-total pressure composite comb probe. The duct is located around the rotor. The flexible variable housing is installed in the internal flow channel of the duct downstream of the stator. The outer side of the flexible variable housing is the flexible variable housing outer cavity. The flexible variable housing outer cavity is connected to the suction pipe and the vacuum pump, and a control valve is installed on the suction pipe. The rotor is mechanically connected to the drive motor through a transmission shaft. The intake cone is connected to the rotor. The exhaust cone is located downstream of the drive motor and the duct. The outlet of the duct is provided with an outlet total temperature-total pressure composite comb probe.

5. The flexible variable casing control method according to claim 1, which takes into account the multi-state power matching requirements of the electric propulsion ducted fan, is characterized in that, The flexible variable casing uses a pressure differential driven intelligent composite material so that the internal flow channel profile of the flexible variable casing is a continuous and smooth sine function under pressure differential drive.

6. The flexible variable casing control method according to claim 1, which takes into account the multi-state power matching requirements of the electric propulsion ducted fan, is characterized in that, The upstream casing of the flexible variable casing has a static pressure measuring hole arranged in the flow channel for measuring the static pressure p4 in the upstream casing of the flexible variable casing.

7. The flexible variable casing control method according to claim 1, which takes into account the multi-state power matching requirements of the electric propulsion ducted fan, is characterized in that, The position with the smallest radius of the flexible variable casing is the flexible variable casing throat. The actual radius R41 of the flexible variable casing throat is: 0.90Rs≤R41≤1.02Rs, where Rs is the radius of the flexible variable casing throat when the pressure difference between the inside and outside of the flexible variable casing is zero.

8. The flexible variable casing control method for balancing the multi-state power matching requirements of electric propulsion ducted fans according to claim 1, characterized in that, The length L of the flexible variable casing is: 0.10Rs≤L≤0.40Rs, where Rs is the radius of the throat of the flexible variable casing when the pressure difference between the inside and outside of the flexible variable casing is zero.

9. The flexible variable casing control method according to claim 4, which takes into account the multi-state power matching requirements of the electric propulsion ducted fan, is characterized in that, The outlet total temperature-total pressure composite comb probe is a radially 5-point comb probe, distributed in an equal toroidal pattern in the radial direction; the total pressure probe of the outlet total temperature-total pressure composite comb probe is a three-hole probe, and the outlet total pressure p of the electric propulsion ducted fan is obtained by processing the data measured by the three pressure measuring holes. t5 Static pressure p5, flow velocity V5.

Images