Noise Reduction Method and Device for Duct Based on Electric Vertical Take-Off and Landing Design
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HANGZHOU INTERNATIONAL INNOVATION INSTITUTE OF BEIHANG UNIVERSITY
- Filing Date
- 2026-01-27
- Publication Date
- 2026-05-26
Smart Images
Figure CN121583231B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of aircraft noise reduction technology, and in particular to a ducted noise reduction method and device based on electric vertical take-off and landing design. Background Technology
[0002] With the acceleration of urbanization and the increasing severity of ground traffic congestion, Urban Air Mobility (UAM), as an innovative transportation solution, is gradually becoming an important direction for the future development of urban transportation.
[0003] However, compared to traditional aircraft (most of which fly at altitudes above 2,000 meters), eVTOL (Electric Vertical Take-off and Landing) aircraft fly at lower altitudes, approximately 300 to 1,000 meters, resulting in serious noise pollution problems that urgently need to be addressed. Summary of the Invention
[0004] This application provides a ducted noise reduction method and device based on electric vertical takeoff and landing (eVTOL) design to solve the serious noise pollution caused by eVTOL aircraft.
[0005] The first aspect of this application provides a duct noise reduction method based on an electric vertical takeoff and landing (EVTOL) design, comprising the following steps: determining the target noise to be reduced in the duct of a target EVTOL aircraft; obtaining target Helmholtz resonator units that meet different frequency requirements based on the target noise to be reduced and a preset resonant frequency expression of a Helmholtz resonator, and determining corresponding resonance noise reduction unit parameters according to the target Helmholtz resonator units; determining the distribution ratio of the target Helmholtz resonator units based on the resonance noise reduction unit parameters, and distributing the target Helmholtz resonator units inside the acoustic liner of the target EVTOL aircraft duct according to the distribution ratio to construct a target sound absorber; and performing noise reduction processing on the blade noise and tubular cavity resonance noise generated by the target EVTOL aircraft during operation based on the target sound absorber.
[0006] Optionally, in one embodiment of this application, determining the target noise to be reduced in the duct of the target electric vertical takeoff and landing aircraft includes: determining the noise frequency expressions corresponding to the blade passage noise and the tubular cavity resonance noise, and determining the duct characteristics corresponding to the target electric vertical takeoff and landing aircraft duct; and determining the target noise to be reduced corresponding to the blade passage noise and the tubular cavity resonance noise based on the noise frequency expressions, the duct characteristics, and a preset power-law attenuation model.
[0007] Optionally, in one embodiment of this application, the step of obtaining target Helmholtz resonator units that meet different frequency requirements based on the target noise to be reduced and a preset resonant frequency expression of the Helmholtz resonator, and determining the corresponding resonant noise reduction unit parameters based on the target Helmholtz resonator units, includes: determining target Helmholtz resonator units with different aperture diameters that meet different frequency requirements based on the resonant frequency expression, and constructing a corresponding noise reduction array using the target Helmholtz resonator units; and determining the resonant noise reduction unit parameters corresponding to the noise reduction array in the duct of the target electric vertical take-off and landing aircraft based on the target noise to be reduced and the resonant frequency expression.
[0008] Optionally, in one embodiment of this application, determining the distribution ratio of the target Helmholtz resonator unit based on the resonant noise reduction unit parameters, and distributing the target Helmholtz resonator unit inside the acoustic liner of the target electric vertical takeoff and landing aircraft duct according to the distribution ratio to construct a target sound absorber, includes: determining the distribution ratio of the target Helmholtz resonator unit in the noise reduction array based on the target noise to be reduced, so that the noise reduction array is distributed inside the acoustic liner of the target electric vertical takeoff and landing aircraft duct according to the distribution ratio and a preset staggered arrangement strategy to establish a corresponding duct liner model, and constructing the target sound absorber based on the duct liner model.
[0009] Optionally, in one embodiment of this application, the expression for the resonant frequency is:
[0010]
[0011] in, is the resonant frequency; c is the speed of sound; A is the orifice diameter; V is the cavity volume; L is the tube length.
[0012] A second aspect of this application provides a duct noise reduction device based on an electric vertical takeoff and landing (EVTOL) design, comprising: a first determining module for determining target noise to be reduced in the duct of a target EVTOL aircraft; a second determining module for obtaining target Helmholtz resonator units that meet different frequency requirements based on the target noise to be reduced and a preset Helmholtz resonator resonator frequency expression, so as to determine corresponding resonance noise reduction unit parameters according to the target Helmholtz resonator units; a construction module for determining the distribution ratio of the target Helmholtz resonator units based on the resonance noise reduction unit parameters, and distributing the target Helmholtz resonator units inside the acoustic liner of the target EVTOL aircraft duct according to the distribution ratio, so as to construct a target sound absorber; and a noise reduction module for performing noise reduction processing on blade passage noise and tubular cavity resonance noise generated by the target EVTOL aircraft during operation based on the target sound absorber.
[0013] Optionally, in one embodiment of this application, the first determining module includes: a first analysis unit, configured to determine the noise frequency expressions corresponding to the blade passing noise and the tubular cavity resonance noise, and to determine the duct characteristics corresponding to the target electric vertical takeoff and landing aircraft duct; and a second analysis unit, configured to determine the target noise to be reduced corresponding to the blade passing noise and the tubular cavity resonance noise based on the noise frequency expressions, the duct characteristics, and a preset power-law attenuation model.
[0014] Optionally, in one embodiment of this application, the second determining module includes: a component unit, configured to determine target Helmholtz resonator units with different aperture diameters that meet different frequency requirements according to the resonant frequency expression, and to construct a corresponding noise reduction array through the target Helmholtz resonator units; and a parameter determining unit, configured to determine the resonant noise reduction unit parameters corresponding to the noise reduction array in the duct of the target electric vertical take-off and landing aircraft based on the target noise to be reduced and the resonant frequency expression.
[0015] Optionally, in one embodiment of this application, the construction module includes: a building unit, configured to determine the distribution ratio of the target Helmholtz resonator unit in the noise reduction array based on the target noise to be reduced, so that the noise reduction array is distributed inside the acoustic liner of the duct of the target electric vertical take-off and landing aircraft according to the distribution ratio and a preset staggered arrangement strategy, so as to establish a corresponding duct liner model, and construct the target sound absorber based on the duct liner model.
[0016] Optionally, in one embodiment of this application, the expression for the resonant frequency is:
[0017]
[0018] in, is the resonant frequency; c is the speed of sound; A is the orifice diameter; V is the cavity volume; L is the tube length.
[0019] A third aspect of this application provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the ducted noise reduction method based on electric vertical take-off and landing design as described in the above embodiments.
[0020] A fourth aspect of this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described ducted noise reduction method based on an electric vertical takeoff and landing design.
[0021] A fifth aspect of this application provides a computer program product, including a computer program that is executed to implement the above-described ducted noise reduction method based on an electric vertical take-off and landing design.
[0022] Therefore, the embodiments of this application have the following beneficial effects:
[0023] The embodiments of this application can determine the target noise to be reduced in the duct of a target electric vertical takeoff and landing (eVTOL) aircraft; based on the target noise to be reduced and a preset Helmholtz resonator resonator frequency expression, target Helmholtz resonator units that meet different frequency requirements are obtained, and corresponding resonance noise reduction unit parameters are determined according to the target Helmholtz resonator units; based on the resonance noise reduction unit parameters, the distribution ratio of the target Helmholtz resonator units is determined, and the target Helmholtz resonator units are distributed inside the acoustic liner of the target eVTOL aircraft duct according to the distribution ratio to construct a target sound absorber; and the target sound absorber is used to reduce the blade noise and tubular cavity resonance noise generated by the target eVTOL aircraft during operation. This application significantly reduces noise pollution to the environment by installing an optimized noise reduction liner on the inner wall of the duct to efficiently reduce rotor noise generated by eVTOL. Thus, it solves the serious noise pollution problems caused by eVTOL aircraft.
[0024] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description
[0025] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:
[0026] Figure 1This is a flowchart illustrating a duct noise reduction method based on an electric vertical take-off and landing design, according to an embodiment of this application.
[0027] Figure 2 A schematic diagram of a silent culvert system provided for one embodiment of this application;
[0028] Figure 3 A schematic modeling diagram of an acoustically lined culvert system provided for one embodiment of this application;
[0029] Figure 4 A schematic diagram of the residuals of different parameters measured in a control group, provided for one embodiment of this application;
[0030] Figure 5 A schematic diagram of the residuals of different parameters measured in an experimental group, provided for one embodiment of this application;
[0031] Figure 6 An outlet flow rate diagram of a control group is provided as an embodiment of this application;
[0032] Figure 7 An experimental group outlet flow rate diagram is provided as an embodiment of this application;
[0033] Figure 8 A control group mass flow diagram is provided as an embodiment of this application;
[0034] Figure 9 An experimental group mass flow diagram is provided as an embodiment of this application;
[0035] Figure 10 This is an example diagram of a duct noise reduction device based on an electric vertical take-off and landing design according to an embodiment of this application;
[0036] Figure 11 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application.
[0037] Among them, 10-Culvert noise reduction device based on electric vertical take-off and landing design; 100-First determining module, 200-Second determining module, 300-Construction module, 400-Noise reduction module; 1101-Memory, 1102-Processor, 1103-Communication interface. Detailed Implementation
[0038] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.
[0039] The following describes a duct noise reduction method and apparatus based on an electric vertical takeoff and landing (eVTOL) design, with reference to the accompanying drawings. Addressing the problems mentioned in the background art, this application provides a duct noise reduction method based on an eVTOL design. In this method, the target noise to be reduced in the duct of a target eVTOL aircraft is determined; based on the target noise and a preset Helmholtz resonator frequency expression, target Helmholtz resonator units meeting different frequency requirements are obtained, and corresponding resonance noise reduction unit parameters are determined according to the target Helmholtz resonator units; based on the resonance noise reduction unit parameters, the distribution ratio of the target Helmholtz resonator units is determined, and the target Helmholtz resonator units are distributed inside the acoustic liner of the target eVTOL duct according to the distribution ratio to construct a target sound absorber; the target sound absorber is used to reduce the blade noise and tubular cavity resonance noise generated by the target eVTOL aircraft during operation. This application significantly reduces noise pollution to the environment by installing an optimized noise reduction liner on the inner wall of the duct to efficiently reduce rotor noise generated by eVTOL. This solved the serious noise pollution problem caused by eVTOL aircraft.
[0040] Specifically, Figure 1 A flowchart illustrating a duct noise reduction method based on an electric vertical take-off and landing design provided in this application embodiment.
[0041] like Figure 1 As shown, the duct noise reduction method based on electric vertical take-off and landing design includes the following steps:
[0042] In step S101, the target noise to be reduced in the duct of the target electric vertical take-off and landing aircraft is determined.
[0043] Those skilled in the art should understand that, regarding passive noise reduction, traditional passive sound absorbers typically include porous materials and resonant sound absorbers. The sound absorption mechanism of porous materials stems from the thermoelastic damping and viscous loss as sound waves propagate through the material's pores; for porous materials backed by a rigid wall, their size is limited by the target wavelength. Generally, they exhibit optimal sound absorption in the high-frequency range. However, to absorb low- and mid-frequency noise, the material thickness must be significantly increased. Therefore, due to space constraints, porous materials are unsuitable for small lined ducts in eVTOL (electrically driven aircraft). On the other hand, the acoustic damping mechanism of resonant sound absorbers primarily relies on viscous and thermal dissipation caused by the intense oscillation of air molecules at the neck at the resonant frequency. They perform well in attenuating low-frequency noise but are only effective within a narrow frequency band.
[0044] Therefore, the embodiments of this application take into account both traditional passive sound absorbers, comprehensively analyze their advantages and disadvantages, and finally select the optimized Helmholtz resonator as the basic noise reduction unit. Its compact structure enables it to produce a good noise reduction effect in the small duct space of the eVTOL aircraft. By setting a set of noise reduction units with different structural parameters, it can achieve a noise reduction effect in a wide noise frequency band.
[0045] In actual implementation, the embodiments of this application can first analyze the blade passage noise and tubular cavity resonance noise generated by the duct of the eVTOL aircraft to determine the target noise to be reduced that is suitable for duct noise reduction by the Helmholtz resonator in the embodiments of this application, thereby providing reliable data support for subsequent duct noise reduction.
[0046] Optionally, in one embodiment of this application, determining the target noise to be reduced in the duct of the target electric vertical takeoff and landing aircraft includes: determining the noise frequency expressions corresponding to the blade passage noise and the tubular cavity resonance noise, and determining the duct characteristics corresponding to the target electric vertical takeoff and landing aircraft duct; and determining the target noise to be reduced corresponding to the blade passage noise and the tubular cavity resonance noise based on the noise frequency expressions, the duct characteristics, and a preset power-law attenuation model.
[0047] It should be noted that the noise generated by the duct of the eVTOL aircraft is mainly divided into two parts: one is the noise generated by the rotation of the propeller inside the duct, that is, the noise of the blade passing through, which is the main source of duct noise; the other is the noise generated by the resonance of the duct cavity, that is, the resonance noise of the tubular cavity.
[0048] For blade passing noise, the fundamental frequency is defined as the frequency at which the propeller or fan blade passes a certain point. In this embodiment, the blade passing frequency can be calculated using the following formula:
[0049]
[0050] in, The fundamental frequency (i.e., the frequency at which the blade passes through) is measured in Hz. This refers to the number of leaves; The passing frequency of a single blade.
[0051] Because the blades transmit noise frequencies including fundamental frequency and higher harmonics. ... (n=1,2,3,.....), the embodiments of this application can determine the blade noise frequency by studying a 12-bladed propeller with a single blade passing through a frequency of 100 Hz (rotation speed of 6000 RPM). (This propeller parameter is typical of an eVTOL aircraft propeller and is representative. Subsequent simulations and physical experiments are also based on this propeller model.) Through calculation, it can be seen that the noise frequency generated by this propeller is a fundamental frequency of 1200 Hz and an overtone of 1200 Hz.
[0052] Furthermore, the energy of the noise's harmonics gradually decreases relative to the fundamental frequency as n increases, and this decrease follows a power-law attenuation model. ,k∈[1,3], where, Let be the amplitude of the noise. It is understandable that for small and medium-sized aircraft, such as eVTOLs, the k-value is approximately 2, indicating that the amplitude of the harmonics generating the noise decreases with the square of the frequency. Since the amplitude from the third harmonic onwards (n=4) is approximately only one-sixteenth of the fundamental frequency, its energy is much less than the fundamental frequency noise. Therefore, this application's embodiments only target the fundamental frequency noise and the first two harmonics (i.e., the target noise to be reduced corresponding to the blade passage noise) for noise reduction.
[0053] For resonant noise in tubular ducts, the origin is the repeated reflection and superposition of sound waves inside the cavity, forming standing waves. When the frequency of external disturbances (such as fan rotation or airflow pulsation) is exactly equal to the natural frequency of a certain resonant mode of the cavity, resonance occurs, resulting in a significantly amplified, sharp noise. For fan ducts, the resonant noise type is open-tube resonance (open at both ends), and the noise frequency satisfies the following formula:
[0054] n=1,2,3,.....,
[0055] Where L is the cavity length; c is the speed of sound; and n represents the order of the resonance mode.
[0056] For the duct model studied in the embodiments of this application, its fundamental frequency f The calculated frequency is 2450 Hz, and the multiplication factor is 2450. n, n = 2, 3, 4... Since its harmonics are almost all greater than 5000 Hz, this requires a large volume of the Helmholtz resonant unit to match it. However, this is difficult to implement due to the narrow space of the eVTOL duct. In addition, considering that the harmonic energy attenuation of the tubular cavity resonance noise also satisfies the power-law attenuation model, its energy is relatively small. Therefore, in the embodiments of this application, only the first-order resonance noise of the tubular cavity (i.e. the target noise to be reduced corresponding to the tubular cavity resonance noise) is considered.
[0057] In step S102, based on the target noise to be denoised and the preset resonant frequency expression of the Helmholtz resonator, a target Helmholtz resonator unit that meets different frequency requirements is obtained, so as to determine the corresponding resonant noise reduction unit parameters according to the target Helmholtz resonator unit.
[0058] Furthermore, embodiments of this application can construct target Helmholtz resonator units that meet different frequency requirements based on the above-mentioned target noise to be reduced and the resonant frequency expression of the Helmholtz resonator, thereby determining the resonant noise reduction unit parameters corresponding to the target Helmholtz resonator unit.
[0059] Optionally, in one embodiment of this application, based on the target noise to be reduced and a preset resonant frequency expression of the Helmholtz resonator, target Helmholtz resonator units that meet different frequency requirements are obtained, so as to determine the corresponding resonant noise reduction unit parameters according to the target Helmholtz resonator units, including: determining target Helmholtz resonator units with different aperture diameters that meet different frequency requirements according to the resonant frequency expression, and constructing a corresponding noise reduction array through the target Helmholtz resonator units; and determining the resonant noise reduction unit parameters corresponding to the noise reduction array in the duct of the target electric vertical take-off and landing aircraft based on the target noise to be reduced and the resonant frequency expression.
[0060] It should be noted that the embodiments of this application may use a Helmholtz resonator for resonance noise reduction. The sound absorption principle of the Helmholtz resonator is: when the frequency of the external sound wave is close to the natural frequency of the resonator, the air column vibrates and the energy is converted into heat energy in the cavity, thereby achieving the sound absorption effect. The embodiments of this application can construct a set of Helmholtz resonators with resonance frequencies of 1200HZ, 2400HZ and 3600HZ respectively by adjusting their structural parameters, thereby achieving resonance sound absorption of the three frequency bands of blade passing noise and the first-order resonance noise of the tubular cavity.
[0061] Optionally, in one embodiment of this application, the expression for the resonant frequency is:
[0062]
[0063] in, is the resonant frequency; c is the speed of sound; A is the orifice diameter; V is the cavity volume; L is the tube length.
[0064] In actual implementation, the resonant frequency formula of the Helmholtz resonator in this embodiment is:
[0065]
[0066] in, is the resonant frequency; c is the speed of sound (generally taken as 343m / s); A is the orifice diameter; V is the cavity volume; L is the tube length.
[0067] As shown in the above formula, under the condition of a fixed sound velocity, the resonant frequency depends only on the magnitudes of A, V, and L. In this embodiment, the Helmholtz resonators V and L are set to the same value, and only the orifice diameter A is used as the independent variable, setting up a noise reduction array composed of three Helmholtz resonators with different orifice diameters. To ensure that the resonant frequencies of the three structural units reach 1200Hz, 2400Hz, and 3600Hz respectively, and to make the three parameter values as small and uniform as possible, after multiple theoretical calculations, the following parameters (i.e., resonant noise reduction unit parameters) were finally determined in this embodiment, as shown in Table 1:
[0068] Table 1
[0069]
[0070] Furthermore, since the fundamental frequency, harmonic frequency, and first-order resonant noise of the blade passing through the tube cavity have different energies, the distribution of the three Helmholtz resonator units in the acoustic liner cannot be uniform. In order to achieve the highest sound absorption efficiency in a limited space, the distribution ratio of these three Helmholtz resonator units should follow their energy ratio. Through energy calculation of these different frequency bands of noise, it was finally determined that the proportion of Helmholtz resonators at resonant frequencies of 1200Hz, 2400Hz, and 3600Hz should be approximately 4:2:1.
[0071] Therefore, the embodiments of this application determine resonator units with different orifice diameters based on the resonant frequency expression, build a noise reduction array to adapt to multi-frequency noise reduction requirements, and accurately determine the parameters of the resonant noise reduction unit in the duct based on the noise to be reduced, thereby improving the targeting and effect of duct noise reduction for eVTOL aircraft.
[0072] In step S103, based on the parameters of the resonant noise reduction unit, the distribution ratio of the target Helmholtz resonator unit is determined, and the target Helmholtz resonator unit is distributed inside the acoustic liner of the target electric vertical take-off and landing aircraft duct according to the distribution ratio, so as to construct the target acoustic absorber.
[0073] In step S104, noise reduction processing is performed on the blade noise and tubular cavity resonance noise generated by the target electric vertical take-off and landing aircraft during operation based on the target sound absorber.
[0074] In actual implementation, the embodiments of this application mainly include two parts: passive noise reduction and active noise reduction. In terms of passive noise reduction, the embodiments of this application can design and demonstrate an optimal sound absorber with a compact size. The absorber is composed of an array of multiple heterogeneous Helmholtz resonators and is embedded in the inner wall of the duct. The absorber can effectively absorb sound within a predetermined frequency range. The sound absorber based on heterogeneous Helmholtz resonators provides reliable technical guidance and basis for achieving sound absorption in the compact size of eVTO.
[0075] Optionally, in one embodiment of this application, based on the parameters of the resonant noise reduction unit, the distribution ratio corresponding to the target Helmholtz resonator unit is determined, and the target Helmholtz resonator unit is distributed inside the acoustic liner of the target electric vertical takeoff and landing aircraft duct according to the distribution ratio to construct the target sound absorber. This includes: based on the target noise to be noise-reduced, determining the distribution ratio corresponding to the target Helmholtz resonator unit in the noise reduction array, so that the noise reduction array is distributed inside the acoustic liner of the target electric vertical takeoff and landing aircraft duct according to the distribution ratio and a preset staggered arrangement strategy to establish a corresponding duct liner model, and constructing the target sound absorber based on the duct liner model.
[0076] As one possible approach, the duct acoustic liner model in this embodiment can be created using Catia software. By selecting the dimensional parameters of the three Helmholtz resonator units from the table above, three different models were established, which are hollow cylindrical containers with openings (as shown in the figure). The tube length L and the internal volume V of these three noise reduction units are the same. The orifice diameters D from left to right are 2mm, 4mm, and 6mm, respectively.
[0077] Secondly, based on the ratio (4:2:1) of the three structural units analyzed above on the duct liner, a model of the duct liner was established through a staggered arrangement. This noise reduction unit was built on the smooth curved surface of the duct inner wall, with four 2mm diameter, two 4mm diameter, and one 6mm diameter, totaling seven Helmholtz resonant units, arranged alternately along the H-axis. Subsequently, in this embodiment, using seven units as a basic array, 36 resonant arrays (containing a total of 36*7 resonant units) were replicated at 10 equal angles along the central rotation axis of the duct, ensuring the resonant units were evenly distributed on the curved surface of the duct inner wall. The duct has an outer diameter of 110mm, an inner diameter of 100mm, and a length of 70mm, for subsequent simulation and 3D printing.
[0078] This application embodiment is based on a ducted noise reduction system model (including the duct and propeller) built on Catia, and performs physical simulation using the Fluent module in ANSYS. In the physical simulation, this application embodiment designed two sets of simulation objects, with the control group as follows: Figure 2 As shown, the experimental group is as follows Figure 3 As shown, the control group is a ducted system without an acoustic liner, and the experimental group is a ducted system with an acoustic liner. The two groups are identical except for the presence or absence of an acoustic liner. This embodiment simulates the noise energy and thrust generated by the ducted system under real-world operating conditions. The purpose is to compare the noise levels of the experimental group relative to the control group, to determine the sound absorption coefficient of the duct with the optimized acoustic liner, and simultaneously compare the thrust of the experimental and control groups to determine the impact of the optimized acoustic liner on the thrust of the ducted system.
[0079] Subsequently, embodiments of this application can import the models of the control group and the experimental group into the geometry module of Fluent, use Boolean operations in the geometry module to cut out the fluid domain and the rotation domain, perform mesh drawing, and name each region (e.g., inlet outlet wall rotation).
[0080] Next, in this embodiment of the application, the calculation parameters and calculation equations can be adjusted in the settings, as described below:
[0081] 1. Material setting: The fluid is air;
[0082] 2. Set stickiness: Modes: k-epsilon, realizable, Scalable Wall Functions;
[0083] 3. Set the parameters for the inlet (velocity inlet 200m / s) and outlet (pressure outlet 101kPa) as well as the parameters for the rotating body (6000rev / min);
[0084] 4. Set up acoustics: Use the FW-H mode of Acoustic in the rotating transient acoustic calculation, then define the noise source as a fan, i.e., a rotating body, and define 6 noise receivers to receive noise data. Set them to a three-dimensional symmetrical distribution to obtain uniform noise distribution information.
[0085] 5. Set up the calculation: Select simple mode;
[0086] 6. Set report type: Select reports such as mass average pressure, mass average velocity, and mass flow rate.
[0087] After setup, this embodiment can be initialized and calculations can begin. Once the simulation is complete, the generated ARD file can be imported into Fluent to generate simulation result graphs for the control and experimental groups, including the change in mass flow rate over time in the transient flow simulation; the change in fluid velocity at the outlet over time; residual plots; and graphs showing the change in sound pressure over time. The graphs also include the sound pressure over time curves and transient flow data.
[0088] in, Figure 4 This is a residual plot of different parameters measured in the control group. Figure 5 Residual plots for different parameters measured in the experimental group. For example... Figure 4 , Figure 5 As shown, the horizontal axis (X-axis) represents the number of iteration steps; the vertical axis (Y-axis) represents the order of magnitude of the residual (logscale), with the unit being the logarithmic scale. The smaller the residual, the smaller the deviation between the calculated solution and the previous iteration, and the more stable the system tends to be. Here, k represents turbulent kinetic energy; ε represents turbulent dissipation rate.
[0089] like Figure 4 , Figure 5 As shown, the residuals of most variables in the experimental and control groups are within 10. -7 Up to 10 -15 Between these values, the values are very small, and it is generally considered that the residual decreases to 10. -4 The following is the initial convergence, which indicates that the simulation is very stable and the solution has converged to a high degree.
[0090] Regarding the change of sound pressure over time in the control group and the experimental group, the simulation results of noise sound pressure at different detection points show that the experimental group has a better noise reduction effect than the control group at different detection points.
[0091] Figure 6 This is a flow velocity diagram at the outlet of the control group. Figure 7 This is a flow velocity diagram of the air outlet of the experimental group. Figure 8 This is a mass flow rate diagram for the control group. Figure 9 This is a mass flow rate diagram for the experimental group. (Example:) Figures 6-9 As shown, the horizontal axis (X-axis) represents time; the vertical axis (Y-axis) represents mass flow rate and fluid velocity, respectively.
[0092] At the beginning, there is a rapid oscillation in the mass flow rate and fluid velocity, which then quickly tends to reach equilibrium, indicating that the system is gradually entering a quasi-steady state.
[0093] The thrust of a ducted fan typically comes from the change in fluid momentum, and can be expressed in the following form:
[0094] F = ( - )
[0095] Where F is the thrust (N); The mass flow rate (kg / s) is shown in the graph of mass flow rate versus time. The outlet velocity (m / s) is shown in the graph as the magnitude of the fluid velocity at the outlet changes over time. The inlet velocity (m / s) can be set to 200 m / s. By calculating the steady-state data from the above figure, the thrust of the ducted system under normal operation can be obtained for both the control and experimental groups. For the control group, the calculated thrust is as follows: =55.887N; For the experimental group, the thrust calculation result is: F = 50.151N. According to the results, the addition of acoustic liner has a very small impact on the thrust of the duct, reducing it by about 8%. Moreover, considering that the acoustic liner is added by drilling holes, it actually reduces the weight of the duct. Therefore, the impact of adding acoustic liner on the thrust of the duct can be approximately ignored.
[0096] In the physical experiments, the embodiments of this application and the simulation experiments were conducted with the same control experiments (the control group was a ducted system without a sound liner, and the experimental group was a ducted system with a sound liner). The purpose was to verify whether the experimental group could achieve or meet the level of noise reduction under ideal working conditions as in the simulation experiments in a real working environment (meaning that all noise factors are taken into account).
[0097] This application embodiment first constructs a control group ducted system circuit, wherein the components selected for the control group ducted system circuit are as follows:
[0098] 1. Duct: 90mm in diameter, 70mm in length;
[0099] 2. Propeller: 12 blades;
[0100] 3. Brushless motor: Rated operating frequency is 100Hz (equivalent to 6000PRM);
[0101] 4. ESC: 80A brushless ESC;
[0102] 5. Battery: 6S5100mAh lithium battery.
[0103] In this embodiment, the duct noise was tested using the constructed circuit. Under the rated operating condition of 6000 RPM, a sound pressure meter was used to perform a three-dimensional symmetrical sound pressure measurement on the duct (measurements were made at intervals of approximately 10 cm for the air inlet, air outlet, and side of the duct). To ensure the reliability and consistency of the measurement results, this embodiment performed measurements with equal precision, repeating the same measurement steps five times, and recording the sound pressure levels displayed by the sound pressure meter under different groups and different measurement positions.
[0104] In subsequent embodiments of this application, experimental group experiments were conducted. Under otherwise identical conditions, the original duct's silent outer shell was replaced with a 3D-printed shell with an acoustic liner to investigate the impact of this single variable on the experimental results. After employing the same circuit construction method and performing the same three-dimensional symmetrical sound pressure measurements, the embodiments of this application also recorded the sound pressure meter readings at different measurement locations in different groups.
[0105] Based on the experimental results of the control group and the experimental group, the data recording tables for the control group (Table 2) and the experimental group (Table 3) were plotted.
[0106] Table 2
[0107]
[0108] Table 3
[0109]
[0110] For the control group, the average sound pressure in the three parts surrounding the duct is: =78.26dB =76.44dB, =80.96dB;
[0111] For the experimental group, the average sound pressure in the three parts surrounding the duct is: =73.88dB =74.84dB, =75.72dB;
[0112] The comparison shows that the noise sound pressure level in the experimental group is significantly lower. The following analysis examines the relationship between the noise energy levels of the control and experimental groups: sound pressure level and energy satisfy the formula: I = ,in, Atmospheric pressure; ρ is the density of the medium (air); c is the speed of sound. Under the experimental conditions (25°C)... Take the standard atmospheric pressure as 101 kPa. The air density at 25°C is taken as 1.18 kg / m³, and c is taken as the air speed of sound at 25°C as 346 m / s.
[0113] Calculations show that the sound intensity (sound energy) at the intake of the control group is about 2.72 times that of the intake of the experimental group; the sound intensity (sound energy) at the exhaust of the control group is about 1.44 times that of the exhaust of the experimental group; and the sound intensity (sound energy) at the side of the duct of the control group is about 3.35 times that of the side of the duct of the experimental group.
[0114] In summary, the experimental results show that, within the target frequency range, compared with rigid pipes, acoustically lined pipes achieve significant noise reduction in both point source and propeller noise source conditions. This reduction is particularly noticeable in terms of auditory perception, transforming harsh noise into soothing and acceptable noise.
[0115] The duct noise reduction method based on electric vertical takeoff and landing (EVTOL) design proposed in this application involves: determining the target noise to be reduced in the duct of a target EVTOL aircraft; obtaining target Helmholtz resonator units that meet different frequency requirements based on the target noise and a preset Helmholtz resonator frequency expression; determining corresponding resonance noise reduction unit parameters based on the target Helmholtz resonator units; determining the distribution ratio of the target Helmholtz resonator units based on the resonance noise reduction unit parameters; distributing the target Helmholtz resonator units inside the acoustic liner of the target EVTOL duct according to the distribution ratio to construct a target sound absorber; and using the target sound absorber to reduce the blade noise and tubular cavity resonance noise generated by the target EVTOL aircraft during operation. This application significantly reduces noise pollution to the environment by installing an optimized noise reduction liner on the inner wall of the duct to efficiently reduce rotor noise generated by EVTOL.
[0116] Secondly, the duct noise reduction device based on the electric vertical take-off and landing design proposed according to the embodiments of this application is described with reference to the accompanying drawings.
[0117] Figure 10 This is a block diagram of a duct noise reduction device based on an electric vertical take-off and landing design, according to an embodiment of this application.
[0118] like Figure 10 As shown, the duct noise reduction device 10 based on electric vertical take-off and landing design includes: a first determining module 100, a second determining module 200, a construction module 300, and a noise reduction module 400.
[0119] The first determining module 100 is used to determine the target noise to be reduced in the duct of the target electric vertical take-off and landing aircraft.
[0120] The second determining module 200 is used to obtain target Helmholtz resonator units that meet different frequency requirements based on the target noise to be denoised and the preset resonant frequency expression of the Helmholtz resonator, so as to determine the corresponding resonant noise reduction unit parameters according to the target Helmholtz resonator units.
[0121] The construction module 300 is used to determine the distribution ratio of the target Helmholtz resonator unit based on the resonant noise reduction unit parameters, and distribute the target Helmholtz resonator unit inside the acoustic liner of the target electric vertical take-off and landing aircraft duct according to the distribution ratio, so as to construct the target sound absorber.
[0122] The noise reduction module 400 is used to reduce the noise generated by the blades and the resonant noise of the tubular cavity of the target electric vertical take-off and landing aircraft during operation based on the target sound absorber.
[0123] Optionally, in one embodiment of this application, the first determining module 100 includes: a first analysis unit and a second analysis unit.
[0124] The first analysis unit is used to determine the noise frequency expressions corresponding to the blade passage noise and the tubular cavity resonance noise, and to determine the duct characteristics corresponding to the duct of the target electric vertical take-off and landing aircraft.
[0125] The second analysis unit is used to determine the target noise to be reduced corresponding to the blade passage noise and the tubular cavity resonance noise based on the noise frequency expression, duct characteristics and the preset power-law attenuation model.
[0126] Optionally, in one embodiment of this application, the second determining module 200 includes: a component unit and a parameter determining unit.
[0127] The assembly unit is used to determine the target Helmholtz resonator units with different aperture diameters that meet different frequency requirements according to the resonant frequency expression, and to assemble the corresponding noise reduction array through the target Helmholtz resonator units.
[0128] The parameter determination unit is used to determine the parameters of the resonant noise reduction unit corresponding to the noise reduction array in the duct of the target electric vertical take-off and landing aircraft based on the target noise to be reduced and the resonant frequency expression.
[0129] Optionally, in one embodiment of this application, the construction module 300 includes: a building unit, used to determine the distribution ratio of the target Helmholtz resonator unit in the noise reduction array based on the target noise to be reduced, so that the noise reduction array is distributed inside the acoustic liner of the duct of the target electric vertical take-off and landing aircraft according to the distribution ratio and a preset staggered arrangement strategy, so as to establish a corresponding duct liner model, and construct the target sound absorber based on the duct liner model.
[0130] Optionally, in one embodiment of this application, the expression for the resonant frequency is:
[0131]
[0132] in, is the resonant frequency; c is the speed of sound; A is the orifice diameter; V is the cavity volume; L is the tube length.
[0133] It should be noted that the foregoing explanation of the duct noise reduction method embodiment based on electric vertical take-off and landing design also applies to the duct noise reduction device based on electric vertical take-off and landing design in this embodiment, and will not be repeated here.
[0134] The duct noise reduction device based on electric vertical takeoff and landing (eVTOL) design proposed in this application includes a first determining module 100 for determining the target noise to be reduced in the duct of a target eVTOL aircraft; a second determining module 200 for obtaining target Helmholtz resonator units that meet different frequency requirements based on the target noise to be reduced and a preset Helmholtz resonator resonator frequency expression, so as to determine the corresponding resonance noise reduction unit parameters according to the target Helmholtz resonator units; a construction module 300 for determining the distribution ratio of the target Helmholtz resonator units based on the resonance noise reduction unit parameters, and distributing the target Helmholtz resonator units inside the acoustic liner of the target eVTOL duct according to the distribution ratio, so as to construct a target sound absorber; and a noise reduction module 400 for performing noise reduction processing on the blade passage noise and tubular cavity resonance noise generated by the target eVTOL aircraft during operation based on the target sound absorber. This application significantly reduces noise pollution to the environment by installing an optimized noise reduction liner on the inner wall of the duct to efficiently reduce rotor noise generated by eVTOL.
[0135] Figure 11 A schematic diagram of the structure of an electronic device provided in an embodiment of this application. The electronic device may include:
[0136] The memory 1101, the processor 1102, and the computer program stored on the memory 1101 and executable on the processor 1102.
[0137] When the processor 1102 executes the program, it implements the duct noise reduction method based on the electric vertical take-off and landing design provided in the above embodiments.
[0138] Furthermore, electronic devices also include:
[0139] Communication interface 1103 is used for communication between memory 1101 and processor 1102.
[0140] The memory 1101 is used to store computer programs that can run on the processor 1102.
[0141] The memory 1101 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage.
[0142] If the memory 1101, processor 1102, and communication interface 1103 are implemented independently, then the communication interface 1103, memory 1101, and processor 1102 can be interconnected via a bus to complete communication between them. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized into address buses, data buses, control buses, etc. For ease of representation, Figure 11 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.
[0143] Optionally, in a specific implementation, if the memory 1101, processor 1102, and communication interface 1103 are integrated on a single chip, then the memory 1101, processor 1102, and communication interface 1103 can communicate with each other through an internal interface.
[0144] The processor 1102 may be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application.
[0145] This application also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the above-described ducted noise reduction method based on an electric vertical take-off and landing design.
[0146] This application also provides a computer program product, including a computer program, which, when executed, is used to implement the above-described duct noise reduction method based on electric vertical take-off and landing design.
[0147] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.
[0148] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.
[0149] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or N executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.
[0150] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.
[0151] It should be understood that the various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. If implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.
[0152] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.
[0153] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.
[0154] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.
Claims
1. A duct noise reduction method based on electric vertical take-off and landing design, characterized in that, Includes the following steps: Identify the target noise to be reduced in the duct of the electric vertical takeoff and landing aircraft. Based on the target noise to be reduced and the preset resonant frequency expression of the Helmholtz resonator, target Helmholtz resonator units that meet different frequency requirements are obtained, so as to determine the corresponding resonant noise reduction unit parameters according to the target Helmholtz resonator units. Based on the parameters of the resonant noise reduction unit, the distribution ratio of the target Helmholtz resonator unit is determined, and the target Helmholtz resonator unit is distributed inside the acoustic liner of the duct of the target electric vertical take-off and landing aircraft according to the distribution ratio, so as to construct the target sound absorber. The target sound absorber is used to reduce the noise generated by the blades and the resonant noise of the tubular cavity during the operation of the target electric vertical take-off and landing aircraft. The noise to be reduced in the duct of the target electric vertical takeoff and landing aircraft includes: Determine the noise frequency expressions corresponding to the blade passage noise and the tubular cavity resonance noise, and determine the duct characteristics corresponding to the duct of the target electric vertical take-off and landing aircraft; Based on the noise frequency expression, the duct characteristics, and the preset power-law attenuation model, the target noise to be reduced is determined corresponding to the blade passage noise and the tubular cavity resonance noise. The process involves obtaining target Helmholtz resonator units that meet different frequency requirements based on the target noise to be denoised and a preset resonant frequency expression for the Helmholtz resonator, and determining the corresponding resonant noise reduction unit parameters based on the target Helmholtz resonator units, including: Based on the resonant frequency expression, the cavity volume and orifice length of different target Helmholtz resonator units are set to the same value. Only the orifice diameter is used as the independent variable. A noise reduction array composed of three target Helmholtz resonator units with different orifice diameters is set up. Through multiple preset theoretical calculation operations, the resonant noise reduction unit parameters corresponding to the noise reduction array in the duct of the target electric vertical take-off and landing aircraft are determined so that the resonant frequencies of the three target Helmholtz resonator units reach 1200HZ, 2400HZ and 3600HZ respectively. Energy calculations were performed on the noise of different frequency bands of the target Helmholtz resonator unit to determine that the ratio of the three Helmholtz resonator units with resonant frequencies of 1200Hz, 2400Hz and 3600Hz was 4:2:1, so that the target Helmholtz resonator unit met the preset sound absorption efficiency requirements. The step of determining the distribution ratio of the target Helmholtz resonator unit based on the parameters of the resonant noise reduction unit, and distributing the target Helmholtz resonator unit inside the acoustic liner of the target electric vertical takeoff and landing aircraft duct according to the distribution ratio to construct a target sound absorber includes: Based on the target noise to be reduced, the distribution ratio of the target Helmholtz resonator unit in the noise reduction array is determined so that the noise reduction array is distributed inside the acoustic liner of the target electric vertical take-off and landing aircraft duct according to the distribution ratio and the preset staggered arrangement strategy, so as to establish the corresponding duct liner model, and construct the target sound absorber based on the duct liner model. The expression for the resonance frequency is: in, is the resonant frequency; c is the speed of sound; A is the orifice diameter; V is the cavity volume; L is the tube length.
2. A duct noise reduction device based on an electric vertical take-off and landing design, characterized in that, The duct noise reduction method based on electric vertical take-off and landing design as described in claim 1 includes: The first determining module is used to determine the target noise to be reduced in the duct of the target electric vertical takeoff and landing aircraft. The second determining module is used to obtain target Helmholtz resonator units that meet different frequency requirements based on the target noise to be denoised and the preset resonant frequency expression of the Helmholtz resonator, so as to determine the corresponding resonant noise reduction unit parameters according to the target Helmholtz resonator units. The module is used to determine the distribution ratio of the target Helmholtz resonator unit based on the parameters of the resonant noise reduction unit, and to distribute the target Helmholtz resonator unit inside the acoustic liner of the target electric vertical take-off and landing aircraft duct according to the distribution ratio, so as to construct the target acoustic absorber. The noise reduction module is used to reduce the noise generated by the blades and the resonant noise of the tubular cavity during the operation of the target electric vertical take-off and landing aircraft based on the target sound absorber.
3. The duct noise reduction device based on electric vertical take-off and landing design according to claim 2, characterized in that, The first determining module includes: The first analysis unit is used to determine the noise frequency expressions corresponding to the blade passing noise and the tubular cavity resonance noise, and to determine the duct characteristics corresponding to the duct of the target electric vertical take-off and landing aircraft. The second analysis unit is used to determine the target noise to be reduced corresponding to the blade passage noise and the tubular cavity resonance noise based on the noise frequency expression, the duct characteristics and the preset power-law attenuation model.
4. An electronic device, characterized in that, include: The memory, the processor, and the computer program stored in the memory and executable on the processor, the processor executing the program to implement the duct noise reduction method based on an electric vertical take-off and landing design as described in any one of claims 1.
5. A computer-readable storage medium having a computer program stored thereon, characterized in that, The program is executed by the processor to implement the duct noise reduction method based on the electric vertical take-off and landing design as described in claim 1.
6. A computer program product, comprising a computer program, characterized in that, The computer program is executed to implement the duct noise reduction method based on electric vertical take-off and landing design as described in claim 1.