A fan-nacelle interference sound field simulation test device

Abstract

This application provides a fan-cabin interference sound field simulation test device, relating to the field of aerospace acoustic testing technology, including a fan sound source assembly, a cabin model, a microphone measurement assembly, and a synchronous data acquisition system. The fan sound source assembly includes a fan test piece and an operating condition adjustment assembly for adjusting the rotational speed and gas flow rate of the rotating blade assembly; the cabin model is located on the air inlet side of the fan test piece and offset from the air inlet. The microphone measurement assembly includes a fan sound field microphone group, a bulkhead microphone group, and a cabin interior microphone group, used to measure the fan radiated sound field, bulkhead sound field, and cabin interior sound field, respectively. The synchronous data acquisition system simultaneously acquires the aforementioned sound field data. This application can simulate interference sound fields under different fan operating conditions and relative positions of the fan and cabin, achieving synchronous measurement of the noise source, bulkhead, and cabin interior sound fields, providing an experimental basis for research on fan noise propagation mechanisms and cabin sound insulation and noise reduction.

Description

Technical Field

[0001] This application relates to the field of aviation acoustic testing technology, and more specifically, to a fan-cabin interference sound field simulation test device. Background Technology

[0002] With the development of the civil aviation transportation industry and the continuous improvement of aircraft airworthiness noise requirements, aircraft noise has become a significant factor affecting aircraft environmental adaptability, cabin comfort, and market competitiveness. During operation, aircraft engine fans generate various noise components, including rotor-to-static interference noise, blade passage frequency noise, and broadband aerodynamic noise. This noise radiates outwards and propagates to the fuselage surface, causing acoustic responses in the fuselage walls and further affecting the cabin sound field. Therefore, accurately simulating fan noise and its propagation into the cabin is a crucial foundation for studying the formation mechanism of aircraft cabin noise and developing noise reduction designs.

[0003] Existing aircraft noise tests can be conducted using real aircraft, fuselage prototypes, or large-scale scale models. However, these tests typically suffer from problems such as large equipment scale, high testing costs, long preparation periods, and difficulty in repeatedly adjusting test conditions. Under laboratory conditions, external aircraft noise can be simulated using sound sources such as loudspeakers to conduct fuselage panel sound insulation or cabin sound field tests. This method is convenient for control and repeated testing, but the sound field generated by loudspeakers still differs from the actual aerodynamic noise generated by rotating fans in terms of spectral composition, radiation directionality, and operating condition variations, making it difficult to fully reflect the working characteristics of a real fan sound source.

[0004] For example, Chinese invention patent application CN103063402A discloses a test device for simulating the airflow and line spectrum noise of a turboprop aircraft propeller. This device drives a perforated rotating bladed disk to rotate via a transmission mechanism, and utilizes the rotating bladed disk to periodically cut the airflow provided by an external air source to generate line spectrum noise with an overtone relationship. By adjusting the intensity of the external air source and the rotational speed of the bladed disk, the sound pressure level and frequency distribution of the simulated noise can also be controlled. This solution improves upon the problem that traditional loudspeakers cannot simultaneously simulate propeller line spectrum noise and airflow pulsation, facilitating the conduct of aircraft panel sound insulation tests in the laboratory and improving the controllability and repeatability of the tests.

[0005] However, the aforementioned device primarily simulates propeller line spectrum noise by rotating bladed disks cutting airflow. Its test objects and sound field forms are relatively limited, mainly used to provide external excitation for panel sound insulation tests. The simulated noise generated by this device still differs somewhat from the actual noise generated by an aero-engine axial fan under different speed, flow rate, and pressure conditions. Furthermore, existing test methods typically study the noise source characteristics or local panel sound insulation performance separately, making it difficult to systematically reflect the continuous process of fan noise generation, radiation, propagation into the cabin, and eventual impact on the cabin sound field under unified and controllable test conditions.

[0006] Therefore, how to realistically generate controllable fan noise excitation under laboratory conditions and conduct comprehensive experimental research on the process of fan noise propagating into the cabin and affecting the cabin sound field has become a technical problem that needs to be solved in this field. Summary of the Invention

[0007] The purpose of this application is to provide a fan-nacelle interference acoustic field simulation test device to address the shortcomings of the prior art.

[0008] To achieve the above objectives, the technical solution adopted in this application is as follows: This application provides a fan-nacelle interference sound field simulation test device, including a fan sound source component, a nacelle model, a microphone measurement component, and a synchronous data acquisition system; The fan sound source assembly includes a fan test piece and a condition adjustment assembly. The fan test piece has an air inlet and an air outlet arranged opposite each other along the axial direction, and a rotating blade assembly located between the air inlet and the air outlet. The condition adjustment assembly is used to adjust the rotation speed of the rotating blade assembly and the gas flow rate through the fan test piece. The cabin model includes the fuselage section that encloses the cabin space. The cabin model and the fan test piece are set at intervals. The cabin model is located on the side of the air inlet away from the air outlet, and the orthographic projections of the cabin model and the air inlet on the projection plane perpendicular to the axis of the fan test piece do not overlap. The microphone measurement assembly includes a fan sound field microphone group, a bulkhead microphone group, and an in-cabin microphone group. The fan sound field microphone group includes a free-field microphone located outside the air inlet, used to measure the sound field radiated outward from the air inlet by the fan test piece. The bulkhead microphone group is located in the bulkhead of the fuselage section, and the in-cabin microphone group is located in the in-cabin space and spaced apart from the bulkhead of the fuselage section. The synchronous data acquisition system is connected to the fan sound field microphone group, the bulkhead microphone group, and the cabin microphone group respectively, and is used to synchronously acquire the radiated sound field data of the fan test piece, the bulkhead sound field data of the fuselage section, and the cabin space sound field data.

[0009] Furthermore, the fan test piece is an axial flow fan, which includes a fan housing and a stator blade assembly. An airflow channel connecting the inlet and outlet is formed inside the fan housing. The rotating blade assembly includes a rotor blade assembly rotatably disposed within the airflow channel. The stator blade assembly is fixedly disposed within the airflow channel, located downstream of the rotor blade assembly, and spaced apart from the rotor blade assembly along the airflow direction. The operating condition adjustment component includes a frequency converter drive assembly and a throttling device. The output end of the frequency converter drive assembly is connected to the rotating blade assembly for driving the rotating blade assembly to rotate and adjusting the rotational speed of the rotating blade assembly. The outlet is connected to an outlet channel. The throttling device is disposed within the outlet channel to adjust the effective flow area of ​​the outlet channel, thereby adjusting the gas flow rate through the axial flow fan.

[0010] Furthermore, it also includes a position adjustment support assembly, which includes a support frame, a lifting mechanism, and multiple omnidirectional casters. The nacelle model is mounted on the support frame via the lifting mechanism, which is used to move the nacelle model up and down relative to the support frame to adjust the vertical position of the nacelle model relative to the fan test specimen. Multiple omnidirectional casters are spaced apart at the bottom of the support frame so that the support frame can translate and rotate in the horizontal plane, thereby adjusting the horizontal position of the nacelle model relative to the fan test specimen, as well as the angle between the length direction of the nacelle model and the axis of the fan test specimen in the horizontal plane.

[0011] Furthermore, the cabin model also includes a fairing section connected to the fuselage section at the end facing the fan test piece; the fairing section has a connecting end connected to the fuselage section and a constricted end away from the fuselage section, and the cross-sectional dimensions of the fairing section gradually decrease from the connecting end to the constricted end to form a streamlined outer surface that smoothly transitions from the fuselage section to the constricted end.

[0012] Furthermore, the fuselage section includes a fixed frame and two end sealing members. The fixed frame includes multiple frame components spaced apart along the length of the fuselage section, multiple long stringers extending along the length of the fuselage section and connected to the multiple frame components, and a floor support structure located at the bottom of the fuselage section and connected to the multiple frame components. The two end sealing members are detachably located at both ends of the fuselage section along the length of the fuselage section to seal the cabin space. At least one of the two end sealing members is provided with an openable and closable hatch.

[0013] Furthermore, the fuselage section also includes skin panels and interior components. The skin panels are detachably connected to the side of the fixed frame facing outwards from the cabin. The interior components include a damping layer, a sound insulation layer, and a decorative panel. The damping layer is disposed on the surface of the skin panels facing the cabin space, the decorative panel is detachably connected to the side of the fixed frame facing the cabin space, and the sound insulation layer is disposed between the damping layer and the decorative panel.

[0014] Furthermore, the fan test piece also includes an air intake channel connected to the air inlet, the air intake channel including a rotating measurement section capable of rotating around the axis of the fan test piece; multiple free-field microphones are disposed outside the air inlet, the multiple free-field microphones forming an arc-shaped free-field microphone array, the arc-shaped free-field microphone array being arranged at intervals along an arc-shaped path in a plane including the axis of the fan test piece with the center of the plane where the air inlet is located as the center; the fan sound field microphone group also includes a circumferential microphone array and a rotating measurement microphone array, the circumferential microphone array including multiple wall microphones arranged at intervals along the circumferential direction along the inner wall of the air intake channel, the sound-sensing surface of each wall microphone being flush with the inner wall of the air intake channel; the rotating measurement microphone array is disposed in the rotating measurement section and includes multiple microphones arranged at intervals along the axial direction of the fan test piece, used to obtain the sound mode distribution of the fan inlet sound field.

[0015] Furthermore, multiple measurement sections are spaced apart along the length of the fuselage section, and each measurement section is equipped with multiple bulkhead microphones and multiple cabin microphones. The multiple bulkhead microphones are distributed circumferentially along the bulkhead of the fuselage section, and each bulkhead microphone is embedded in the bulkhead, with the sound-sensing surface of each bulkhead microphone flush with the inner surface of the bulkhead. The multiple cabin microphones are located within the corresponding measurement section and are distributed in a grid pattern along the width and height of the fuselage section to form an array of cabin measurement points corresponding to the measurement section.

[0016] Furthermore, the bulkhead microphone assembly includes multiple inner microphones and multiple outer microphones. The multiple inner microphones are disposed on the inner surface of the bulkhead, and the sound-sensing surface of the inner microphones is flush with the inner surface of the bulkhead. The multiple outer microphones are disposed on the outer surface of the bulkhead. The multiple outer microphones and multiple inner microphones are paired and disposed one-to-one at corresponding positions on the bulkhead to synchronously acquire the sound pressure signals on the inner and outer sides of the corresponding positions on the bulkhead.

[0017] Furthermore, at least some of the in-cabin microphones in the in-cabin microphone group are mounted on a movable measuring frame, which is located in the cabin space and can move the in-cabin microphones mounted on the movable measuring frame between multiple measurement positions in the cabin space, so as to obtain sound pressure signals at multiple measurement positions through the same group of in-cabin microphones.

[0018] The beneficial effects of this application include: This application provides a fan-nacelle interference acoustic field simulation test device. By setting up a fan sound source assembly and using a condition adjustment assembly to adjust the rotational speed of the rotating blade assembly and the gas flow rate through the fan test piece, the same fan test piece can form aerodynamic sound sources under different operating conditions. Compared with the method of using a fixed sound source or preset sound signal for excitation, this is more conducive to realistically reflecting the impact of changes in fan operating status on noise generation and radiation characteristics. At the same time, the nacelle model is set on the air inlet side of the fan test piece and is laterally offset from the air inlet, so that the main airflow of the fan does not directly impact the surface of the nacelle model, but mainly uses the sound field radiated outward from the air inlet to apply acoustic excitation to the nacelle model. With the help of a position adjustment support assembly that can adjust the vertical position, horizontal position and relative angle of the nacelle model, different fan-nacelle relative installation relationships can be simulated on the same test device, providing repeatable test conditions for studying the influence of installation position changes on interference acoustic fields.

[0019] This application establishes corresponding microphone measurement structures on the fan side, cabin bulkhead, and cabin interior, and performs synchronous data acquisition through a synchronous data acquisition system. Specifically, the arc-shaped free-field microphone array on the fan inlet side can acquire sound pressure and spectral information in different radiation directions, while the circumferential microphone array and rotating measurement microphone array can further acquire the sound field distribution and acoustic mode information inside the inlet channel. Multiple measurement sections are set along the length of the fuselage section, with bulkhead microphones and cabin microphones synchronously arranged at each section, allowing for the acquisition of the corresponding distribution of the bulkhead sound field and the cabin interior sound field at different locations. This establishes a continuous measurement link from the fan noise source, external radiation, propagation into the cabin, bulkhead response, to the cabin interior sound field, facilitating the analysis of the correlation between each propagation stage. Compared to acoustic measurements of only a single area, this approach more comprehensively reflects the propagation and attenuation process of fan-cabin interference noise.

[0020] The fuselage section of this application adopts a modular structure combining a fixed frame with replaceable skin panels and interior components. While maintaining the fixed frame and main test boundaries, skin panels of different materials, thicknesses, or structural forms can be replaced. Damping layers, sound insulation layers, and decorative panels can be replaced individually or in combination, thereby reducing structural differences introduced by replacing the entire cabin model. Furthermore, by pairing microphones at corresponding positions inside and outside the cabin wall, sound pressure signals from both sides of the cabin wall can be obtained simultaneously, and the sound insulation performance of the cabin wall can be evaluated. The microphones inside the cabin can also be installed on a movable test frame, allowing measurements to be taken at multiple spatial locations using the same set of microphones. This reduces the number of microphones and acquisition channels while improving the spatial measurement resolution of the cabin sound field. Therefore, this application enables relatively convenient, repeatable, and quantitative comparative evaluation of different cabin wall structures and sound insulation and noise reduction measures.

[0021] Furthermore, this application can acquire fan speed, inlet and outlet aerodynamic parameters, throttling device opening, and related operating and environmental parameters simultaneously with sound field data acquisition. This enables different acoustic measurement results to establish a clear relationship with the corresponding fan operating conditions, thereby reducing the problem of difficulty in determining the actual sound source state based solely on sound pressure results. It is beneficial to compare the directionality, spectral characteristics, acoustic modes, and changes in the propagation of fan noise into the nacelle under different speed, flow rate, and installation conditions.

[0022] In summary, this application integrates an adjustable fan aerodynamic sound source, a nacelle model with adjustable relative position, a modular and replaceable bulkhead structure, and a synchronous sound field measurement system covering the fan side, bulkhead side, and interior side of the nacelle into the same experimental device. This allows for the study of the effects of fan operating conditions, fan-nacelle installation positions, and bulkhead sound insulation and noise reduction schemes on the interference sound field while maintaining consistent main experimental benchmarks. It enables continuous experimental research on fan noise generation, radiation, propagation, and interior response, thereby improving the comparability between different experimental schemes and the reusability of the experimental platform. It also provides a reliable experimental basis for the study of fan-nacelle interference noise mechanisms and low-noise design. Attached Figure Description

[0023] Figure 1 A schematic diagram of the working environment of a fan-nacelle interference acoustic field simulation test device provided in this application; Figure 2 This application provides a schematic diagram showing the relative position of a fan test piece and a nacelle model. Figure 3(a) is a front view of a cabin model provided in this application; Figure 3(b) is a side view of a cabin model provided in this application; Figure 4 A two-dimensional structural schematic diagram of a cabin model provided in this application; Figure 5 This application provides a structural schematic diagram of a fairing section; Figure 6 A structural schematic diagram of a fuselage section provided in this application; Figure 7 This application provides a structural schematic diagram of a fuselage section fixed frame; Figure 8 This application provides a schematic diagram of the structure of a position adjustment support assembly; Figure 9 A schematic diagram of the arrangement of an arc-shaped free-field microphone array provided in this application; Figure 10 A schematic diagram of the arrangement of a rotating measuring microphone array provided in this application; Figure 11 A schematic diagram of the arrangement of a bulkhead microphone assembly provided in this application; Figure 12 This is a schematic diagram of the arrangement of an in-cabin microphone assembly provided in this application.

[0024] Reference numerals: 1-Fan test piece; 11-Intake passage; 12-Rotating measurement section; 2-Nacelle model; 21-Fuselage section; 22-Fairing section; 211-Front end frame; 212-Middle frame; 213-Rear end frame; 214-Stringer; 215-Skin panel; 216-End sealing component; 217-Door; 230-Position adjustment support assembly. Detailed Implementation

[0025] To facilitate the explanation of the spatial relationships between the structures in this embodiment, the axial direction of the fan test piece 1 is taken as the axial direction of the fan test piece 1; in the horizontal plane, the direction perpendicular to the axial direction of the fan test piece 1 is taken as the transverse direction, and the direction perpendicular to the horizontal plane is taken as the vertical direction. The length direction of the fuselage section 21 is the direction in which the fuselage section 21 extends from one end to the other, and the circumferential direction of the fuselage section 21 is the direction in which it extends along the arc-shaped bulkhead contour of the fuselage section 21. The measurement section referred to below refers to the section selected along the length direction of the fuselage section 21 and approximately perpendicular to the length direction of the fuselage section 21.

[0026] like Figure 1 and Figure 2 As shown, this embodiment provides a fan-nacelle interference sound field simulation test device, mainly used to simulate the process of fan noise propagating into the nacelle and acting on the nacelle walls and the interior space under controllable test conditions. The test device includes a fan sound source assembly, a nacelle model 2, a microphone measurement assembly, and a synchronous data acquisition system. The fan sound source assembly is used to form an aerodynamic sound source of the fan with adjustable operating conditions. The nacelle model 2 is used to form a simulated nacelle structure affected by the fan radiated sound field. The microphone measurement assembly is used to acquire the radiated sound field of the fan test piece 1, the sound field at the fuselage section 21 nacelle wall, and the sound field of the interior space, respectively. The synchronous data acquisition system is used to synchronously acquire acoustic signals from different measurement areas. Through the cooperation of the above parts, the processes of fan noise generation, outward radiation, propagation into the nacelle, action on the nacelle walls, and formation of a sound field in the interior space can be continuously studied on the same test platform.

[0027] The fan noise source assembly includes a fan test piece 1 and an operating condition adjustment assembly. The fan test piece 1 has an inlet and an outlet arranged opposite each other along its axial direction, and a rotating blade assembly is disposed between the inlet and outlet. During the test, external gas enters the fan test piece 1 through the inlet and flows towards the outlet along the axial direction of the fan test piece 1 under the action of the rotating blade assembly. The rotating blade assembly generates aerodynamic noise as it rotates and performs work on the airflow. Part of this sound energy can be radiated from the inlet to the outside of the fan test piece 1, thus forming an inlet radiation sound field outside the inlet.

[0028] The operating condition adjustment component is used to regulate the rotational speed of the rotating blade assembly and the gas flow rate through the fan test specimen 1, enabling the same fan test specimen 1 to generate acoustic excitation conditions under different operating conditions. Changing the rotational speed of the rotating blade assembly alters the acoustic characteristics related to blade rotation and periodic aerodynamics; changing the gas flow rate through the fan test specimen 1 changes the interaction state between the rotating blade assembly and the airflow. Therefore, while keeping the main structure of the fan test specimen 1 unchanged, different sound source conditions can be obtained by changing the fan operating conditions, providing an experimental basis for studying the impact of changes in fan operating parameters on noise generation, radiation, and propagation into the nacelle.

[0029] In this embodiment, the fan test piece 1 is a single-stage axial flow fan. The axial flow fan includes a fan housing and a stator blade assembly. An airflow channel connecting the inlet and outlet is formed within the fan housing. The rotating blade assembly includes a rotor blade assembly rotatably disposed within the airflow channel, and the rotor blade assembly includes multiple rotor blades. The stator blade assembly is fixedly disposed within the airflow channel, located downstream of the rotor blade assembly along the airflow direction, and spaced apart from the rotor blade assembly along the airflow direction. External air enters the airflow channel through the inlet, passes through the rotor blade assembly and the stator blade assembly, and is discharged through the outlet. The rotor blade assembly rotates relative to the stator blade assembly, enabling the fan test piece 1 to generate acoustic excitation with the aerodynamic characteristics of an axial flow fan under the action of actual airflow.

[0030] As a specific prototype, the rotor blade assembly can be configured with nineteen rotor blades, and the stator blade assembly can be configured with eighteen stator blades. The rotor blade assembly's rotational speed can be adjusted from 0 to 3000 rpm, the axial fan's pressure ratio can be 1.02, the inlet diameter can be 0.5 m, and the design flow rate can be 6.38 kg / s. The above parameters are a specific set of parameters used for conducting experiments in this embodiment, and other implementation methods are not required to use the same parameters.

[0031] The operating condition adjustment component includes a variable frequency drive assembly and a throttling device. The output end of the variable frequency drive assembly is connected to the rotating blade assembly for driving the rotor blade assembly to rotate and adjusting the speed of the rotor blade assembly. In one specific embodiment, the variable frequency drive assembly includes an AC variable frequency motor and a frequency converter that cooperates with the AC variable frequency motor. The output shaft of the AC variable frequency motor is connected to the rotating shaft of the rotating blade assembly via a coupling. The power of the AC variable frequency motor can be 18.5 kW. By adjusting the output state of the frequency converter, the operating speed of the AC variable frequency motor is changed, thereby changing the actual speed of the rotor blade assembly.

[0032] The air outlet of fan test piece 1 is connected to an air outlet channel, and a throttling device is disposed within the air outlet channel. In one specific embodiment, the throttling device is a throttling valve. By changing the opening degree of the throttling valve, the effective flow area of ​​the air outlet channel is changed, thereby adjusting the flow resistance of fan test piece 1 and the gas flow rate through the axial flow fan. The frequency converter drive assembly and the throttling device work together to adjust the rotational speed of the rotor blade assembly and the gas flow rate through the axial flow fan, respectively, so that fan test piece 1 reaches the preset operating conditions.

[0033] like Figure 1 and Figure 2 As shown, the nacelle model 2 and the fan test piece 1 are spaced apart and located on the side of the air inlet away from the air outlet, that is, the nacelle model 2 is arranged on the air inlet side of the fan test piece 1. The sound waves radiated outward from the air inlet propagate through the space between the fan test piece 1 and the nacelle model 2 and then act on the nacelle model 2. The main airflow generated by the fan test piece 1 enters through the air inlet and flows along the axis of the fan test piece 1 towards the air outlet. Therefore, the main airflow does not directly impact the surface of the nacelle model 2, so that the main excitation acting on the nacelle model 2 is the sound field radiated outward from the fan inlet.

[0034] Furthermore, the orthographic projections of the nacelle model 2 and the air inlet on the projection plane perpendicular to the axis of the fan test piece 1 do not overlap, so that the nacelle model 2 avoids the direct projection area of ​​the air inlet in the lateral direction. By adopting the above-mentioned staggered arrangement, the air intake state of the fan test piece 1 can be significantly changed by the nacelle model 2 directly blocking the air inlet, and the additional disturbances caused by the direct action of the fan airflow on the nacelle model 2 can be reduced, so that the test can be more focused on the acoustic process of the sound field radiated from the fan inlet propagating to the nacelle model 2.

[0035] As shown in Figure 3 to Figure 5 As shown, the cabin model 2 includes a fuselage section 21 and a fairing section 22. The fuselage section 21 encloses an interior space for simulating the internal environment of the cabin and adopts a straight structure with a basically consistent cross-section along its length. As a specific prototype, the fuselage section 21 can be 1200 mm long, 1200 mm wide, and 600 mm high.

[0036] The fairing section 22 is connected to the end of the fuselage section 21 facing the fan test piece 1. The fairing section 22 has a connecting end connected to the fuselage section 21 and a converging end away from the fuselage section 21. The cross-sectional dimensions of the fairing section 22 gradually decrease from the connecting end to the converging end, forming a streamlined outer surface that continuously transitions from the fuselage section 21 to the converging end. In this embodiment, the fairing section 22 can adopt a hyperbolic streamlined shape and an integral structure. As a specific dimension, the length of the fairing section 22 can be 900 mm, the width of its connecting end can be 1200 mm (matching the width of the fuselage section 21), and the height of its connecting end can be 600 mm (matching the height of the fuselage section 21). Along the direction from the connecting end to the converging end, the width of the fairing section 22 gradually decreases to 0 mm, and the height gradually decreases to 150 mm. The fuselage section 21 and the fairing section 22 are connected by a butt joint, ensuring structural connection while forming a continuous external profile.

[0037] In one specific assembly method, the connecting end of the fairing section 22 is connected to the frame assembly of the fuselage section 21 near the fairing section 22, and the relative assembly position between the fairing section 22 and the fuselage section 21 is determined by scribing and positioning, thereby ensuring that the two are aligned in the predetermined position. A reinforcing member is provided in the middle of the fairing section 22, and the reinforcing member is connected to the position adjustment support assembly 230 to support the fairing section 22 and improve the stability of the fairing section 22 during testing.

[0038] In an implementation that requires simulating external airflow conditions during flight, an air blowing device can be installed at the front of the cabin model 2, so that the airflow generated by the air blowing device flows through the outside of the cabin model 2, and the streamlined outer surface of the fairing section 22 guides the airflow at the front of the cabin model 2 to simulate the state of fan noise propagating to the cabin model 2 when there is external airflow.

[0039] As shown in Figure 3 and Figure 8 As shown, the cabin model 2 is supported by a position adjustment support assembly 230. The position adjustment support assembly 230 includes a support frame, a lifting mechanism, and multiple swivel casters. The support frame is located below the cabin model 2 and is used to support the cabin model 2. The cabin model 2 is installed on the support frame via the lifting mechanism, and the multiple swivel casters are spaced apart at the bottom of the support frame.

[0040] In one specific embodiment, the lifting mechanism employs a hydraulic lifting structure and is connected to the nacelle model 2 via a floor beam in the floor support structure and a reinforcing member in the middle of the fairing section 22. This allows the fuselage section 21 and the fairing section 22 to be jointly supported by the position adjustment support assembly 230, and their vertical positions can be changed along with the lifting mechanism as a whole. The adjustment range of the lifting mechanism can be 0–400 mm, used to change the vertical position of the nacelle model 2 relative to the fan test piece 1 and the vertical drop between the fan test piece 1 and the fuselage section 21. In one specific test state, the height of the retracted end of the fairing section 22 above the ground can be 1100 mm.

[0041] Multiple omnidirectional casters enable the support frame to translate and rotate within the horizontal plane of the test site. Moving the support frame along the axis of the fan test specimen 1 changes the axial distance between the nacelle model 2 and the fan test specimen 1; moving the support frame in a direction perpendicular to the axis of the fan test specimen 1 within the horizontal plane changes the lateral offset of the nacelle model 2 relative to the fan test specimen 1; rotating the support frame within the horizontal plane changes the angle between the length direction of the nacelle model 2 and the axis of the fan test specimen 1. Combined with the lifting mechanism, the axial distance, lateral offset, vertical position, and relative angle between the nacelle model 2 and the fan test specimen 1 can be adjusted, thereby simulating interference sound fields under different fan-nacelle installation conditions.

[0042] The bottom of the support frame of the position adjustment support assembly 230 is also equipped with multiple adjustable support feet, the support height of which can be adjusted. After the cabin model 2 is moved to the predetermined test position using the casters, the adjustable support feet can be adjusted to support it on the test site, and the support frame can be leveled and stabilized to reduce the possibility of unexpected movement of the support frame during the test. When it is necessary to readjust the horizontal position of the cabin model 2, the adjustable support feet can be released from their ground support state, allowing the casters to resume their function of moving the support frame.

[0043] like Figure 6 and Figure 7 As shown, fuselage section 21 adopts a modular configuration combining a fixed frame and replaceable bulkhead structure. The fixed frame includes multiple frame components spaced apart along the length of fuselage section 21, multiple stringers 214 extending along the length of fuselage section 21 and connected to the multiple frame components, and a floor support structure located at the bottom of fuselage section 21. The frame components form lateral support foundations at different length positions of fuselage section 21, the multiple stringers 214 span different frame components and form a longitudinal support structure extending along the length of fuselage section 21, and the floor support structure connects to the bottom area of ​​multiple frame components, so that the frame components, stringers 214, and floor support structure together constitute a fixed frame for maintaining the geometry of fuselage section 21 and supporting the bulkhead structure.

[0044] In the specific prototype of this embodiment, the fuselage section 21 is provided with three frame components spaced apart along its length: a front frame 211 located near the fairing section 22, a middle frame 212 located in the middle of the fuselage section 21, and a rear frame 213 located away from the fairing section 22. The front frame 211 has a T-shaped cross-section and is used to connect the fuselage section 21 and the fairing section 22. Its width can be 50 mm and its height can be 30 mm. The middle frame 212 and the rear frame 213 have Z-shaped cross-sections, and their width can be 25 mm. The middle frame 212 has a through hole on the side facing the skin panel 215 for the passage of the stringer 214. The height of the through hole can be 50 mm. The rear frame 213 does not have a corresponding stringer passage hole. The front frame 211, the middle frame 212, and the rear frame 213 are all integral structures. In the specific prototype of this embodiment, the length of each of the three frame components can be 1884 mm.

[0045] Multiple stringers 214 are arranged at intervals along the circumferential region of the fuselage section 21 and extend along the length of the fuselage section 21. In one specific embodiment, the stringers 214 are continuous structures with a length of up to 1200 mm, and the spacing between adjacent stringers 214 can be approximately 100 mm. Stringer corner pieces are provided at the connections between the stringers 214 and the front frame 211, the middle frame 212, and the rear frame 213. These corner pieces can be L-shaped, with a length of 100 mm, a height of 30 mm, and a width of 30 mm. Near the fairing section 22, stringer joints can also be provided at the ends of the stringers 214 to strengthen the connection between the stringers 214 and the front frame 211. When the stringer joint is L-shaped, its length can be 100 mm and its height can be 25 mm.

[0046] The floor support structure is located at the bottom of the fuselage section 21. In one specific embodiment, the floor support structure includes floor beams, vertical beams, and honeycomb flooring. The floor beams connect the bottom ends of the front frame 211, the middle frame 212, and the rear frame 213, and can have a C-shaped or Z-shaped cross-section, with a length of 1200 mm, a width of 30 mm, and a height of 80–100 mm. The vertical beams are installed vertically on the upper surface of the floor beams, and can also have a C-shaped or Z-shaped cross-section, with a length of 500 mm, a width of 40 mm, and a height of 60–80 mm. Guide rails are provided in the floor support area, and honeycomb flooring is laid in the area formed between the guide rails and the floor beams. The honeycomb flooring can have a width of 594 mm and a length of 1200 mm.

[0047] Connectors can also be installed between the floor support structure and the side panels of the fuselage section 21, forming a connection between the bottom structure and the side structure of the fuselage section 21. Sound-absorbing carpet is laid on the side of the honeycomb floor facing the cabin space. This carpet reduces the reflection of sound waves from the floor surface, thereby reducing the impact of floor-reflected sound on the cabin sound field measurement. It should be noted that the guide rail used for laying the honeycomb floor in the floor support area belongs to the floor structure of the fuselage section 21. This embodiment does not limit this guide rail to the movable guide structure of the movable test frame described later.

[0048] End sealing members 216 are respectively provided at both ends of the fuselage section 21 along its length. The two end sealing members 216 are detachably installed at the end openings of the fuselage section 21 to seal the fuselage section 21 and form relatively independent internal spaces. In one specific embodiment, the end sealing members 216 are made of wood with a thickness of approximately 30 mm. An openable and closable hatch 217 is provided on the end sealing member 216 on the side away from the fairing section 22. The hatch 217 is detachably connected to the end sealing member 216 by a latch, thereby facilitating access for test personnel to install microphones, lay wiring, disassemble and assemble bulkhead structures, and adjust measurement positions. The material of the end sealing members 216 can also be changed according to different sound insulation test schemes.

[0049] The fuselage section 21 also includes a skin panel 215 and interior trim components. The skin panel 215 is detachably connected to the side of the fixed frame facing outwards from the cabin and forms the external acoustic surface of the fuselage section 21. Sound waves radiated from the fan test piece 1 to the cabin model 2 propagate to the fuselage section 21 and act on the skin panel 215, resulting in corresponding acoustic and structural responses after being subjected to external sound pressure. In one specific embodiment, the skin panel 215 is an integral aluminum alloy panel with an arc-shaped structure adapted to the frame assembly of the fuselage section 21. The length of the skin panel 215 along the length direction of the fuselage section 21 can be 1200 mm, and the arc length can be 1884 mm.

[0050] Interior components are disposed on the side of the skin panel 215 facing the cabin space, including a damping layer, a sound insulation layer, and a decorative panel. The damping layer is disposed on the surface of the skin panel 215 facing the cabin space; in one specific embodiment, the damping layer is directly adhered to the inner surface of the skin panel 215. The sound insulation layer is disposed between the damping layer and the decorative panel, and may be made of sound insulation cotton. The decorative panel is located on the side of the sound insulation layer facing the cabin space and is detachably connected to the fixed frame. Viewed from outside the cabin to inside, the skin panel 215, the damping layer, the sound insulation layer, and the decorative panel sequentially form the external sound-receiving structure and the internal sound insulation and interior structure of the fuselage section 21.

[0051] The decorative panel can be connected to the fixed frame via connectors, and the connection points may include the front frame 211, the middle frame 212, the rear frame 213, and the stringer 214. In one specific connection method, the decorative panel includes two panels extending from both sides of the fuselage section 21 towards the top. The two panels are joined at the top of the fuselage section 21 and are detachably connected to the corresponding frame components via brackets, nuts, and bolts, thereby facilitating the installation and removal of the decorative panel. A sound insulation layer is filled between the damping layer and the decorative panel.

[0052] The fixed framework formed by the front frame 211, middle frame 212, rear frame 213, stringer 214, floor beams, vertical beams, and honeycomb floor remains unchanged throughout the same series of comparative tests. However, the skin panels 215 and interior components can be replaced according to the test objectives. Specifically, the decorative panels, sound insulation layer, and damping layer can be replaced individually or in combination; the skin panels 215 can be entirely replaced with panels of different materials, thicknesses, or structural forms. The material type, laying method, number of layers, or surface density of the damping and sound insulation layers can also be changed, as can the material of the end sealing components 216. This allows for testing of different bulkhead structures and sound insulation schemes while maintaining the main load-bearing structure of the fuselage section 21 unchanged.

[0053] In the replaceable bulkhead area, other sound-absorbing structures, sound-insulating structures, or active control units can be installed according to the test objectives. When conducting comparative tests of different noise reduction schemes, the fixed frame, fan sound source conditions, relative positions of the cabin model 2, and corresponding microphone measurement point positions can be kept consistent, while changing the skin panel 215, interior components, or other noise reduction structures to be evaluated. After the replaceable structure is reinstalled, it can be restored to the installation position corresponding to the corresponding test state, allowing different bulkhead schemes to be repeatedly compared under the same main geometric boundaries and measurement position conditions, reducing measurement differences introduced by changes in the overall test setup.

[0054] To measure the sound source and radiation characteristics of fan test piece 1, the fan sound field microphone group in the microphone measurement assembly includes multiple free-field microphones disposed outside the air inlet. These multiple free-field microphones can form an arc-shaped free-field microphone array. For example... Figure 9 As shown, the arc-shaped free-field microphone array is centered on the center of the plane containing the air inlet and lies within the plane including the axis of the fan test piece 1. Multiple free-field microphones are arranged at intervals along the arc-shaped path. Since different free-field microphones have different sound radiation observation directions relative to the air inlet, sound pressure signals corresponding to different radiation angles can be obtained.

[0055] In one specific arrangement of this embodiment, the radius of the arc-shaped free-field microphone array is not less than 2 m. Taking the axis of the fan test piece 1 along the air intake direction as the 0° direction, a free-field microphone is set at 6° intervals from 0° to 90°. Based on the sound pressure measurement results obtained at different radiation angles, the distribution of the fan inlet radiated sound field as a function of the radiation direction can be obtained, and the noise directivity index can be obtained according to the corresponding acoustic evaluation method. Furthermore, the sound pressure signals obtained at different measurement points can be subjected to spectral analysis to obtain the spectral characteristics of the fan inlet radiated noise under different operating conditions.

[0056] The fan test piece 1 also includes an air intake channel 11 communicating with the air inlet. The fan sound field microphone group also includes a circumferential microphone array, which includes multiple wall microphones spaced circumferentially along the inner wall of the air intake channel 11. In one specific embodiment, the multiple wall microphones are arranged at equal intervals circumferentially along the inner wall of the air intake channel 11, and the sensing surface of each wall microphone is flush with the inner wall of the air intake channel 11, thereby avoiding the sensing end of the microphone from protruding significantly into the airflow channel, reducing the disturbance of the microphone installation to the airflow and local sound field inside the air intake channel 11, and obtaining wall sound pressure data at different circumferential positions of the air intake channel 11.

[0057] The air intake passage 11 includes a rotating measuring section 12 capable of rotating about the axis of the fan test piece 1. For example... Figure 10 As shown, a rotating measuring microphone array is provided on the rotating measuring section 12, which includes multiple microphones spaced apart along the axial direction of the fan test piece 1. By rotating the rotating measuring section 12 around the axis of the fan test piece 1, the measuring positions of the microphones mounted on the rotating measuring section 12 in the circumferential direction of the air intake channel 11 can be changed, thereby acquiring sound pressure data at multiple spatial positions of the air intake channel 11 using a limited number of microphones.

[0058] In one specific embodiment, the rotating measuring microphone array includes two linear microphone arrays, which are respectively positioned at two radially opposite circumferential positions on the rotating measuring section 12 and spaced 180° apart circumferentially along the rotating measuring section 12. Each linear microphone array includes fourteen microphones spaced apart along the axial direction of the fan test piece 1, with an axial spacing of 24 mm between adjacent microphones. The two linear microphone arrays cooperate with the circumferential rotation of the rotating measuring section 12 to acquire sound pressure data at multiple axial and circumferential positions of the air intake channel 11, and based on this, perform circumferential and radial sound mode decomposition of the fan inlet sound field to obtain the modal composition of the fan inlet sound field under different operating conditions.

[0059] The arc-shaped free-field microphone array, the circumferential microphone array, and the rotating measurement microphone array have different measurement functions. The arc-shaped free-field microphone array is mainly used to characterize the radiation directionality and spectral characteristics of fan noise in the external space after leaving the air inlet; the circumferential microphone array is used to obtain the wall sound pressure at different circumferential positions within the air intake channel 11; and the rotating measurement microphone array is used to obtain multi-position data of the inlet sound field and perform acoustic modal analysis. Combining these different measurement results allows for the characterization of the sound field on the fan inlet side from both spatial radiation characteristics and inlet acoustic modal characteristics.

[0060] In some embodiments, an outlet free-field microphone array can be installed outside the outlet of the fan test specimen 1 to measure the sound field radiated outward from the outlet. The outlet free-field microphone array is signal-connected to a synchronous data acquisition system, enabling synchronous acquisition with the inlet-side fan sound field microphone group, the bulkhead microphone group, and the cabin microphone group. With the outlet free-field microphone array installed, external radiated sound field data from both the inlet and outlet sides can be obtained simultaneously.

[0061] On one side of the cabin model 2, the microphone measurement assembly includes bulkhead microphone groups and cabin microphone groups. Multiple measurement sections are spaced apart along the length of fuselage section 21, with multiple bulkhead microphones and multiple cabin microphones arranged simultaneously on each section. The bulkhead microphones and cabin microphones use corresponding measurement sections along the length of fuselage section 21; that is, bulkhead microphones and cabin microphones belonging to the same measurement section have the same or corresponding axial positions. This allows a correspondence to be established between the bulkhead sound field and the cabin space sound field in the same axial region. With multiple measurement sections distributed along the length of fuselage section 21, changes in the sound field at different axial positions can also be compared.

[0062] like Figure 11 As shown, at each measurement section, multiple bulkhead microphones are distributed circumferentially along the bulkhead of fuselage section 21. In one specific embodiment, the multiple bulkhead microphones are evenly arranged circumferentially along the skin panel 215. Each bulkhead microphone is embedded in the bulkhead, so that the sensing surface of the bulkhead microphone is flush with the inner surface of the bulkhead and does not protrude into the interior space. By adopting the above-mentioned flush embedding method, the sensing surface can obtain the local sound pressure at the inner surface of the bulkhead, and reduce the disturbance of the microphone protruding structure to the sound field near the bulkhead and the airflow near the bulkhead, thereby improving the accuracy of bulkhead sound pressure distribution measurement.

[0063] In the docking area between the fairing section 22 and the fuselage section 21, the density of bulkhead microphones can be increased. This area corresponds to the transition from the fairing section 22 to the fuselage section 21 when the fan inlet radiated sound field propagates along the outside of the cabin model 2 towards the fuselage section 21. By adding measuring points in this area, more detailed local sound pressure distribution information can be obtained.

[0064] To obtain the sound insulation characteristics of different locations or a large area of ​​the cabin bulkhead, the bulkhead microphone group can also include multiple inner microphones and multiple outer microphones. The bulkhead microphones located on the inner surface of the bulkhead can serve as inner microphones, with their sound-sensing surfaces flush with the inner surface of the bulkhead; outer microphones are placed at corresponding positions on the outer surface of the bulkhead, so that the outer microphones are paired with the inner microphones at corresponding positions on the bulkhead. Depending on the test objective, the aforementioned paired inner and outer microphones can be placed at corresponding positions on some measurement sections, or multiple sets of paired microphones can be placed over a large area of ​​the fuselage section 21.

[0065] The inner and outer microphones are synchronously acquired through a synchronized data acquisition system, enabling direct comparison of sound pressure signals from both sides within the same local bulkhead area. Based on the synchronously acquired sound pressure data from both sides of the corresponding location on the bulkhead, the sound pressure changes before and after the sound waves pass through the corresponding bulkhead structure can be compared. The transmission loss at the corresponding location or bulkhead area can be calculated using appropriate acoustic evaluation methods, thereby quantitatively evaluating the sound insulation performance of the bulkhead structure formed by the skin panel 215 and interior components. Furthermore, the sound pressure data from the inner and outer sides of the bulkhead can be correlated with the cabin sound field data at the same measurement section, establishing a correlation between the bulkhead sound pressure response and cabin sound radiation.

[0066] like Figure 12 As shown, the cabin microphones and bulkhead microphones share the aforementioned axial measurement cross-section. Within each measurement cross-section, multiple cabin microphones are arranged in a grid pattern along the width and height directions of the fuselage section 21 to form an array of cabin measurement points that matches the corresponding measurement cross-section. After multiple measurement cross-sections are distributed along the length direction of the fuselage section 21, the spatial distribution information of the cabin sound field along the length, width, and height directions of the fuselage section 21 can be obtained by combining the grid pattern of cabin measurement points in each measurement cross-section.

[0067] The in-cabin microphone is positioned within the cabin space and spaced apart from the bulkhead of fuselage section 21. This allows the in-cabin microphone to primarily acquire sound pressure within the cabin space, while the bulkhead microphone is primarily used to acquire sound pressure at the bulkhead boundaries. The two types of microphones perform different measurement tasks. In this embodiment, the in-cabin microphone is preferably positioned away from the bulkhead, and the sound-absorbing carpet laid on the honeycomb floor reduces the influence of sound reflections from the bulkhead and floor on the measurement results, making the measurement state of the in-cabin microphone closer to free-field measurement conditions.

[0068] In another method of measuring the cabin acoustic field, at least some of the cabin microphones in the cabin microphone array are mounted on a movable frame. The movable frame is positioned within the cabin space and can move the same set of cabin microphones mounted on it between multiple measurement locations within the cabin space. During measurement, the sound pressure signal at one measurement location can be acquired using this set of cabin microphones, and then the position of the movable frame can be changed to acquire the sound pressure signal at another measurement location. By repeatedly changing the position of the movable frame, the same set of cabin microphones can cover more spatial measurement points, thereby obtaining high spatial resolution cabin acoustic field data while reducing the number of microphones and acquisition channels used.

[0069] When using a movable measuring frame for multi-position measurements, the frame can be moved sequentially to different measurement positions and measurements can be taken while the fan test piece 1 maintains the same stable operating condition. If it is necessary to change the fan's operating state during the movement of the measuring frame, the fan test piece 1 can be brought back to the same preset operating condition before each measurement, and then the sound pressure signal at the corresponding position can be collected, ensuring that the data from different spatial measurement positions have comparable sound source conditions. The specific moving support structure of the movable measuring frame is not particularly limited, as long as it enables the cabin microphone it carries to move between multiple predetermined cabin measurement positions and complete the corresponding sound pressure measurements.

[0070] As one method of acoustic testing, each microphone and its corresponding acquisition channel can be calibrated before formal measurements begin to reduce the impact of differences in microphone sensitivity and acquisition channel on the measurement results. Measurement point numbers can also be established for each microphone on the fan side, bulkhead side, and interior side, and a correspondence can be established between these measurement point numbers and the spatial location of the corresponding microphone and the acquisition channel in the synchronous data acquisition system. This facilitates the identification and association of data obtained from different microphones according to the measurement location during subsequent data processing.

[0071] The synchronous data acquisition system is connected to the fan sound field microphone group, the bulkhead microphone group, and the cabin microphone group, respectively. Each microphone outputs a corresponding electrical signal after being subjected to sound pressure, and transmits this signal to the synchronous data acquisition system. In this embodiment, synchronous acquisition refers to different acoustic measurement channels acquiring and recording corresponding signals according to a unified time reference, enabling data obtained from different measurement points at the same sampling time or within corresponding sampling time periods to establish a time correspondence. Therefore, the sound field inside the fan inlet, the external radiated sound field of the air inlet, the bulkhead sound field of fuselage section 21, and the cabin space sound field can be acquired synchronously under the same fan operating conditions; when an outlet free-field microphone array is set, the radiated sound field on the fan outlet side can also be acquired synchronously.

[0072] Furthermore, this embodiment can also simultaneously acquire the operating condition parameters and test environment parameters of the fan test piece 1. In one specific embodiment, a speed monitoring instrument is installed at the shaft end of the rotating blade assembly to acquire the actual speed of the rotor blade assembly; static pressure rings and total pressure and temperature rakes are respectively installed at the corresponding sections of the air inlet and outlet of the fan test piece 1 to acquire the pressure and temperature parameters at the corresponding locations, and thereby determine the pressure ratio and temperature rise of the fan test piece 1, as well as calculate the gas flow rate and corresponding aerodynamic parameters.

[0073] The throttling device can also be equipped with an opening sensor to obtain the actual opening degree of the throttling device. When the throttling device is a throttling valve, the detection range of the opening degree sensor can correspond to 0-100% of the valve opening degree. Output frequency, voltage, current, and shaft power can also be read through the inverter communication interface in the frequency converter drive assembly, and atmospheric pressure, ambient temperature, and relative humidity in the test environment can be collected. Fan operating parameters and test environment parameters are recorded according to time information corresponding to the acoustic data, thereby establishing a clear data correspondence between different fan operating conditions and corresponding environmental conditions and acoustic measurement results.

[0074] In a specific test, the rotational speed of the rotor blade assembly can be adjusted first through the frequency converter drive component, and the effective flow area of ​​the outlet channel can be adjusted through the throttling device to bring the fan test piece 1 to the preset operating conditions. After the adjustment is completed, the operating status of the fan test piece 1 can be judged based on the detection results of the speed monitor, the throttling device opening sensor, and the inlet and outlet aerodynamic parameters. After the relevant operating parameters reach the preset operating condition range and remain stable, acoustic data acquisition begins.

[0075] After the fan test piece 1 is running stably, it generates aerodynamic noise. The arc-shaped free-field microphone array acquires sound pressure data in different radiation directions on the fan inlet side, the circumferential microphone array acquires the wall sound pressure at different circumferential positions in the air intake channel 11, and the rotating measuring microphone array acquires inlet sound field data at different circumferential angle positions and different axial positions through the rotation of the rotating measuring section 12, which is used to carry out acoustic modal analysis; when the outlet free-field microphone array is configured, the radiated sound field data outside the air outlet is also acquired simultaneously.

[0076] Sound waves radiated outward from the fan inlet propagate through the space between the fan test piece 1 and the nacelle model 2 before reaching the nacelle model 2. Bulkhead microphones acquire the bulkhead sound pressure at different measurement sections and circumferential positions of the fuselage section 21. Paired inner and outer microphones further acquire the sound pressure signals on both sides of the corresponding bulkhead positions. Sound energy entering the cabin space is measured by in-cabin microphones to obtain the cabin sound field at the corresponding measurement section. A synchronous data acquisition system simultaneously records acoustic signals from the fan side, bulkhead side, and in-cabin side, along with corresponding fan operating parameters and environmental parameters, ensuring that data from different propagation stages within the same test period can be correlated.

[0077] Based on data obtained synchronously in a single experiment, the relationship between fan operating conditions and the directionality, directivity index, spectral characteristics, and inlet acoustic modes of the radiated sound field can be analyzed. The difference between the sound field on the fan side and the sound field at location 2 in the nacelle model can be compared to analyze the changes in fan radiated noise during its propagation into the nacelle. The sound insulation performance of the corresponding bulkhead structure can be evaluated based on the sound pressure data and transmission loss on both the inner and outer sides of the bulkhead. Furthermore, the relationship between the bulkhead acoustic response and the sound field inside the nacelle can be analyzed by combining the bulkhead sound pressure and the sound pressure of the nacelle space at the same axial measurement section. Therefore, a continuous synchronous measurement link can be established from the fan noise source, external radiation, propagation into the nacelle, bulkhead sound insulation, to the sound field inside the nacelle space.

[0078] When it is necessary to study the influence of fan operating conditions on the interference sound field, the structure of the nacelle model 2 and its position relative to the fan test piece 1 can be kept unchanged, and the rotational speed and gas flow rate of the rotor blade assembly can be changed respectively. The sound field measurement can then be repeated under each preset stable operating condition. When it is necessary to study the influence of the relative installation position of the fan and the nacelle on the interference sound field, the fan operating conditions and the structure of the nacelle model 2 can be kept unchanged. The axial distance, lateral offset, vertical position, or relative angle of the nacelle model 2 relative to the fan test piece 1 can be changed by adjusting the position support component 230, and the measurement can then be repeated at the adjusted predetermined position.

[0079] When studying the effects of different bulkhead structures or noise reduction schemes, the fixed frame, fan operating conditions, relative positions of the cabin model 2, and corresponding measuring point arrangements can be kept unchanged. The skin panel 215, damping layer, sound insulation layer, decorative panel, end sealing component 216, or noise reduction structures located in replaceable areas can be replaced, and the sound field data before and after replacement can be compared. Alternatively, with different fan-side noise reduction measures applied to the fan test piece 1, the cabin model 2 and corresponding measuring arrangements can be kept unchanged. The fan radiation sound field, the bulkhead sound field of the fuselage section 21, and the cabin sound field under different fan sound source conditions can be compared. This allows for comparative studies of sound source conditions, relative installation positions, and sound insulation and noise reduction schemes using the same test platform.

[0080] Through the aforementioned structure and experimental methods, this embodiment sets up an adjustable-operation-condition fan aerodynamic sound source, an adjustable-position nacelle model 2, a modular and replaceable nacelle bulkhead structure, and a multi-region sound field measurement system covering the fan side, bulkhead side, and interior side of the nacelle, all within the same reusable experimental platform. By simultaneously acquiring acoustic data at different propagation stages and corresponding fan operating condition parameters, the generation, spatial radiation, propagation into the nacelle, bulkhead sound insulation, and sound field formation processes of fan noise can be studied. Furthermore, while maintaining consistent main experimental conditions, the acoustic performance of different sound source conditions, different fan-nacelle relative installation relationships, and different sound insulation and noise reduction schemes can be compared, providing repeatable experimental conditions for the study of fan-nacelle interference noise mechanisms and control.

[0081] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A fan-nacelle interference acoustic field simulation test device, characterized in that, This includes fan sound source components, a cabin model, microphone measurement components, and a synchronous data acquisition system; The fan sound source assembly includes a fan test piece and a condition adjustment assembly. The fan test piece has an air inlet and an air outlet arranged opposite each other along the axial direction, and a rotating blade assembly located between the air inlet and the air outlet. The condition adjustment assembly is used to adjust the rotation speed of the rotating blade assembly and the gas flow rate through the fan test piece. The cabin model includes the fuselage section that encloses the cabin space. The cabin model and the fan test piece are set at intervals. The cabin model is located on the side of the air inlet away from the air outlet, and the orthographic projections of the cabin model and the air inlet on the projection plane perpendicular to the axis of the fan test piece do not overlap. The microphone measurement assembly includes a fan sound field microphone group, a bulkhead microphone group, and an in-cabin microphone group. The fan sound field microphone group includes a free-field microphone located outside the air inlet, used to measure the sound field radiated outward from the air inlet by the fan test piece. The bulkhead microphone group is located in the bulkhead of the fuselage section, and the in-cabin microphone group is located in the in-cabin space and spaced apart from the bulkhead of the fuselage section. The synchronous data acquisition system is connected to the fan sound field microphone group, the bulkhead microphone group, and the cabin microphone group respectively, and is used to synchronously acquire the radiated sound field data of the fan test piece, the bulkhead sound field data of the fuselage section, and the cabin space sound field data.

2. The fan-nacelle interference acoustic field simulation test device according to claim 1, characterized in that, The fan test piece is an axial flow fan, which includes a fan housing and a stator blade assembly. An airflow channel is formed inside the fan housing, connecting the inlet and outlet. The rotating blade assembly includes a rotor blade assembly rotatably disposed within the airflow channel. The stator blade assembly is fixedly disposed within the airflow channel, located downstream of the rotor blade assembly, and spaced apart from the rotor blade assembly along the airflow direction. The operating condition adjustment assembly includes a frequency converter drive assembly and a throttling device. The output end of the frequency converter drive assembly is connected to the rotating blade assembly for driving the rotating blade assembly to rotate and adjusting the rotational speed of the rotating blade assembly. The outlet is connected to an outlet channel. The throttling device is disposed within the outlet channel to adjust the effective flow area of ​​the outlet channel, thereby adjusting the gas flow rate through the axial flow fan.

3. The fan-nacelle interference acoustic field simulation test device according to claim 1, characterized in that, It also includes a position adjustment support assembly, which includes a support frame, a lifting mechanism, and multiple swivel casters. The nacelle model is mounted on the support frame via the lifting mechanism, which is used to move the nacelle model up and down relative to the support frame to adjust the vertical position of the nacelle model relative to the fan test specimen. Multiple swivel casters are spaced apart at the bottom of the support frame so that the support frame can translate and rotate in the horizontal plane, thereby adjusting the horizontal position of the nacelle model relative to the fan test specimen, as well as the angle between the length direction of the nacelle model and the axis of the fan test specimen in the horizontal plane.

4. The fan-nacelle interference acoustic field simulation test device according to claim 1, characterized in that, The cabin model also includes a fairing section connected to the fuselage section at the end facing the fan test piece. The fairing section has a connecting end connected to the fuselage section and a constricted end away from the fuselage section. The cross-sectional dimensions of the fairing section gradually decrease from the connecting end to the constricted end to form a streamlined outer surface that smoothly transitions from the fuselage section to the constricted end.

5. The fan-nacelle interference acoustic field simulation test device according to claim 1, characterized in that, The fuselage section includes a fixed frame and two end sealing members. The fixed frame includes multiple frame components spaced apart along the length of the fuselage section, multiple long stringers extending along the length of the fuselage section and connected to the multiple frame components, and a floor support structure located at the bottom of the fuselage section and connected to the multiple frame components. The two end sealing members are detachably installed at both ends of the fuselage section along the length of the fuselage section to seal the cabin space. At least one of the two end sealing members is provided with an openable and closable hatch.

6. The fan-nacelle interference acoustic field simulation test device according to claim 5, characterized in that, The fuselage section also includes skin panels and interior components. The skin panels are detachably connected to the side of the fixed frame facing outwards from the cabin. The interior components include a damping layer, a sound insulation layer, and a decorative panel. The damping layer is disposed on the surface of the skin panels facing the cabin interior space. The decorative panel is detachably connected to the side of the fixed frame facing the cabin interior space. The sound insulation layer is disposed between the damping layer and the decorative panel.

7. The fan-nacelle interference acoustic field simulation test device according to claim 1, characterized in that, The fan test piece also includes an air intake channel connected to the air inlet, the air intake channel including a rotating measurement section capable of rotating around the axis of the fan test piece; multiple free-field microphones are set outside the air inlet, and the multiple free-field microphones form an arc-shaped free-field microphone array, the arc-shaped free-field microphone array is arranged at intervals along an arc-shaped path in a plane including the axis of the fan test piece with the center of the plane where the air inlet is located as the center; the fan sound field microphone group also includes a circumferential microphone array and a rotating measurement microphone array, the circumferential microphone array including multiple wall microphones arranged at intervals along the circumferential direction along the inner wall of the air intake channel, the sound-sensing surface of each wall microphone is flush with the inner wall of the air intake channel; the rotating measurement microphone array is set in the rotating measurement section and includes multiple microphones arranged at intervals along the axial direction of the fan test piece, used to obtain the sound mode distribution of the fan inlet sound field.

8. The fan-nacelle interference acoustic field simulation test device according to claim 1, characterized in that, Multiple measurement sections are spaced along the length of the fuselage section. Each measurement section is equipped with multiple bulkhead microphones and multiple cabin microphones. The multiple bulkhead microphones are distributed circumferentially along the bulkhead of the fuselage section. Each bulkhead microphone is embedded in the bulkhead, and the sound-sensing surface of each bulkhead microphone is flush with the inner surface of the bulkhead. The multiple cabin microphones are located within the corresponding measurement section and are distributed in a grid pattern along the width and height of the fuselage section to form an array of cabin measurement points corresponding to the measurement section.

9. The fan-nacelle interference acoustic field simulation test device according to claim 1, characterized in that, The bulkhead microphone assembly includes multiple inner microphones and multiple outer microphones. The inner microphones are located on the inner surface of the bulkhead, and their sound-sensing surfaces are flush with the inner surface of the bulkhead. The outer microphones are located on the outer surface of the bulkhead. The outer microphones and inner microphones are paired one-to-one at corresponding positions on the bulkhead to synchronously acquire the sound pressure signals from the inner and outer sides of the corresponding positions on the bulkhead.

10. The fan-nacelle interference acoustic field simulation test apparatus according to any one of claims 1 to 9, characterized in that, At least some of the in-cabin microphones in the in-cabin microphone group are mounted on a movable measuring frame, which is located in the cabin space and is capable of moving the in-cabin microphones mounted on the movable measuring frame between multiple measurement positions in the cabin space, so as to acquire sound pressure signals at multiple measurement positions through the same group of in-cabin microphones.

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