Far-field directivity measuring device for fan noise and application

Abstract

The invention belongs to the technical field of aero-engine noise testing, and particularly relates to a fan noise far-field directivity measuring device and application thereof.The fan noise far-field directivity measuring device comprises an anechoic chamber, a single-stage low-speed fan device and a far-field array microphone measuring device.The anechoic chamber comprises an anechoic chamber wall face and an anechoic piece; the silencing pieces are laid on the wall face of the silencing chamber in an array mode, the silencing pieces are sound absorption wedges, one end of the single-stage low-speed fan device is provided with an air inlet horn mouth, and the single-stage low-speed fan device is provided with a front sound liner casing section. The sound absorption performance is excellent, the test precision is guaranteed, the sound absorption wedges laid in the anechoic chamber effectively suppress background noise, it is ensured that the wide-band acoustic test environment meets the requirement, the influence of external interference on the measurement result is avoided, the data reliability is improved, a complex special test bed is not needed, the device building process is simplified, and the cost is reduced. The requirement for special facilities is lowered, construction cost and time are saved, multi-angle noise collection can be directly carried out, and debugging steps are reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft engine noise testing, and in particular relates to a device for measuring far-field directivity of fan noise and its application. Background Art

[0002] Before entering the civil aviation market, new passenger aircraft must undergo flight trials and obtain certification, and noise certification is a crucial component of this process. As the bypass ratio of civil turbofan engines continues to increase, the noise generated by the massive, high-speed rotating fans has become the primary noise source in aircraft engines. Fan noise seriously impacts cabin comfort and also creates significant noise disturbance for residents near airports during takeoff and landing. Furthermore, airworthiness certification methods generally measure the effective perceived noise level in the far field during three operating conditions: flyover, lateral, and approach. To effectively suppress fan noise, it is necessary to understand the source of fan noise. Based on its spectral characteristics, fan noise can be divided into pure tone noise and broadband noise at the blade pass frequency and its harmonics, generated by the interference of the rotor's periodic wake with the stator blade row or outlet guide vanes. In today's engine design, advanced fan blade design, rotor-stator cutoff design, and passive sound absorption measures (including the installation of acoustic liners at the engine inlet and outer duct) have gradually become a design standard, which greatly reduces the fan pure sound. In order to meet more stringent noise certification standards, the study of fan duct broadband noise has become increasingly important. The classification, quantitative analysis and ultimate noise reduction measures of duct broadband noise have become research hotspots. The generation mechanism, propagation sound power, far-field radiation characteristics and effective acoustic liner design of broadband noise all require detailed modal characteristic information in the duct.

[0003] To this end, the present invention provides a device for measuring the far-field directivity of fan noise and its application. Summary of the Invention

[0004] In order to remedy the deficiencies of the prior art and solve the technical problems raised by the above-mentioned background technology, the present invention proposes a device for measuring the far-field directivity of fan noise and its application.

[0005] The technical solution adopted by the present invention to solve its technical problem is: a device for measuring the far-field directivity of fan noise described in the present invention includes an anechoic chamber, a single-stage low-speed fan device and a far-field array microphone measurement device, the anechoic chamber includes an anechoic chamber wall and a anechoic member, the anechoic member array is laid on the anechoic chamber wall, the anechoic member is a sound-absorbing wedge, an air intake bell is provided at one end of the single-stage low-speed fan device, a front sound lining casing section is provided on the single-stage low-speed fan device, a rotor is provided inside the single-stage low-speed fan device, a stator casing is provided on the single-stage low-speed fan device, a stator is provided inside the stator casing, a rear sound lining casing section is provided on the single-stage low-speed fan device, a rear support bearing frame is provided on the single-stage low-speed fan device, a drive motor is provided inside the single-stage low-speed fan device, an output end of the drive motor is fixedly connected to a rotor shaft, and the other end of the rotor shaft is fixedly connected to the center position of the rotor, and the far-field array microphone measurement device is arranged inside the anechoic chamber.

[0006] Preferably, a load-bearing frame and a slide rail are provided below the single-stage low-speed fan device.

[0007] Preferably, the rotor is a single-stage integral blade disk structure with 100 blades, formed by integral casting, with an outer diameter of mm and a tip clearance of mm.

[0008] Preferably, the stator is a single-stage integral casting structure with 100 blades.

[0009] Preferably, the stator casing serves as the main load-bearing frame of the test bench, and is fixedly connected to the front acoustic liner casing section and the rear acoustic liner casing section through flange stops. At the same time, a reinforcing rib is designed between the front and rear flanges to ensure the rigidity of the load-bearing frame.

[0010] Preferably, the front acoustic liner casing section is used to install an acoustic liner for suppressing the forward noise of the fan in the circular duct, and can also be installed with a hard wall section for measuring the sound field in the rigid wall circular duct.

[0011] Preferably, the rear acoustic liner casing section adopts a split casing structure to facilitate installation and disassembly.

[0012] Preferably, the rotor shaft adopts two-point simple support, the front support point is located at the inner ring of the stator casing, and the rear support point is located at the inner ring of the rear support bearing frame.

[0013] Preferably, the front end of the rotor shaft is connected to the rotor through a flange, which is plum blossom-shaped to facilitate the installation of the front fulcrum bearing cover, and the rear end of the rotor shaft is connected to the motor shaft through a coupling to achieve power transmission.

[0014] An application method of a device for measuring far-field directivity of fan noise, comprising:

[0015] S1. First, when measuring the far-field directivity of fan noise, after the air intake bell mouth enters the anechoic chamber, the drive motor will start to drive the rotor shaft to rotate, and the rotation of the rotor shaft will cause the rotor to move;

[0016] S2. When the rotor moves, wind flow enters the anechoic chamber. The noise can be measured using a far-field microphone array. 21 far-field microphones are evenly distributed on a circular arc trajectory 6150mm from the fan center, covering a radiation angle of 0°-180°. 16 wall microphones are synchronously arranged circumferentially in the front and rear sound transmission measurement sections for acoustic mode identification.

[0017] S3. The silencer is a sound-absorbing wedge with good sound absorption effect. It can meet the requirements of background noise, cutoff frequency, etc. in the acoustic environment required for noise testing. There is no need to build a special test bench. The measurement is convenient and the measurement cost is low, which is convenient for noise testing of aircraft engines.

[0018] The beneficial effects of the present invention are as follows:

[0019] The present invention has excellent sound absorption performance to ensure test accuracy. The sound-absorbing wedges laid in the anechoic chamber effectively suppress background noise, ensure that the wide-band acoustic test environment meets the requirements, avoid the influence of external interference on the measurement results, and improve data reliability. No complex special test bench is required. The free-field characteristics of the anechoic chamber replace the traditional pipeline test bench, simplifying the device construction process, reducing the need for special facilities, saving construction costs and time. The far-field microphone array layout combined with the anechoic chamber environment can directly perform multi-angle noise collection, reduce complex debugging steps, and achieve efficient and low-cost noise directivity measurement. It supports rapid replacement of sound lining sections or hard wall sections, which is convenient for comparing the effects of different noise reduction measures, meets the test needs of multiple working conditions and multiple configurations, and improves experimental flexibility. While ensuring high-precision measurement, it significantly reduces the implementation threshold and cost, providing an efficient and universal solution for aircraft engine noise research. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described below with reference to the accompanying drawings.

[0021] Figure 1 1. It is a schematic structural diagram of a device for measuring far-field directivity of fan noise according to the present invention;

[0022] Figure 2 It is a structural schematic diagram of a single-stage low-speed fan in the present invention.

[0023] In the figure: 1. Anechoic chamber; 11. Anechoic chamber wall; 12. Anechoic components; 2. Single-stage low-speed fan; 21. Air intake bell; 22. Front acoustic liner casing section; 23. Rotor; 24. Stator casing; 25. Rear acoustic liner casing section; 26. Rear support bearing frame; 27. Drive motor; 28. Bearing frame and slide rail; 29. Rotor shaft. DETAILED DESCRIPTION

[0024] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0025] like Figure 1 and Figure 2 As shown, a device for measuring the far-field directivity of fan noise according to an embodiment of the present invention comprises an anechoic chamber 1, a single-stage low-speed fan device 2 and a far-field array microphone measuring device 3, the anechoic chamber 1 comprises an anechoic chamber wall 11 and a anechoic member 12, the anechoic member 12 array is laid on the anechoic chamber wall 11, the anechoic member 12 is a sound-absorbing wedge, an air inlet bell mouth 21 is provided at one end of the single-stage low-speed fan device 2, a front sound lining casing section 22 is provided on the single-stage low-speed fan device 2, a rotor 23 is provided inside the single-stage low-speed fan device 2, a stator casing 24 is provided on the single-stage low-speed fan device 2, a stator is provided inside the stator casing 24, a rear sound lining casing section 25 is provided on the single-stage low-speed fan device 2, a rear support bearing frame 26 is provided on the single-stage low-speed fan device 2, and the single-stage low-speed fan device 2 is provided. 2 is provided with a drive motor 27, the output end of which is fixedly connected to the rotor shaft 29, and the other end of the rotor shaft 29 is fixedly connected to the center of the rotor 23. The far-field full-array microphone measurement device 3 is arranged inside the anechoic chamber 1. The single-stage fan device 2 adopts a rotor-stator layout with reference to the structure of a high-bypass-ratio turbofan engine, without inlet guide vanes. Experimental sections for installing acoustic liners are designed in front and behind the single-stage fan, and test sections are also equipped. The anechoic chamber 1 combines a far-field 21-point microphone array with circumferential modal measurement points to achieve simultaneous and high-precision capture of sound pressure levels and acoustic modes across the entire frequency band, meeting the stringent requirements of airworthiness certification. The free-field characteristics of the anechoic chamber 1 avoid the need to build a dedicated duct test bench. Combined with replaceable acoustic liners, a single test can complete the simultaneous evaluation of acoustic liners insertion loss and radiation directivity changes.

[0026] A load-bearing frame and a slide rail 28 are provided below the single-stage low-speed fan device 2 , and the load-bearing frame and the slide rail 28 facilitate the movement of the single-stage low-speed fan device 2 .

[0027] The rotor 23 is a single-stage integral blade disk structure with 11 blades and is integrally cast. The outer diameter of the rotor 23 is 406 mm and the tip clearance is 2 mm. The stator is a single-stage integral casting structure with 18 blades. The stator casing 24 serves as the main load-bearing frame of the test bench and is fixedly connected to the front acoustic liner casing section 22 and the rear acoustic liner casing section 25 through flange stoppers. At the same time, 12 reinforcing ribs are designed between the front and rear flanges to ensure the rigidity of the load-bearing frame.

[0028] The front sound liner casing section 22 is used to install the sound liner to suppress the forward noise of the fan in the circular duct. The hard wall section can also be installed to measure the sound field in the rigid wall circular duct. The rear sound liner casing section 25 adopts a split casing structure, which is easy to install and disassemble.

[0029] The rotor shaft 29 is simply supported at two points, with the front fulcrum located on the inner ring of the stator casing 24 and the rear fulcrum located on the inner ring of the rear fulcrum bearing frame 26. The front end of the rotor shaft 29 is connected to the rotor 23 through a flange. The flange is plum blossom-shaped, which is convenient for the installation of the front fulcrum bearing cover. The rear end of the rotor shaft 29 is connected to the motor shaft through a coupling to realize power transmission.

[0030] An application method of a device for measuring far-field directivity of fan noise, comprising:

[0031] S1. First, when measuring the far-field directivity of the fan noise, after the air intake bell mouth 21 enters the anechoic chamber 1, the drive motor 27 is operated to drive the rotor shaft 29 to rotate, and the rotation of the rotor shaft 29 causes the rotor 23 to move;

[0032] When the rotor 23 moves, wind flow enters the anechoic chamber 1. The noise can be measured by the far-field microphone array measurement device 3. 21 far-field microphones are evenly distributed on a circular arc trajectory 6150 mm from the fan center, covering a radiation angle of 0°-180°. 16 wall microphones are synchronously arranged circumferentially in the front and rear sound transmission measurement sections for acoustic mode identification.

[0033] S3 and the silencer 12 are sound-absorbing wedges with good sound absorption effect. They can meet the requirements of background noise, cutoff frequency, etc. in the acoustic environment required for noise testing. There is no need to build a special test bench, the measurement is convenient, and the measurement cost is low.

[0034] Working principle: First, when measuring the far-field directivity of fan noise, after the air intake bell mouth 21 enters the anechoic chamber 1, the drive motor 27 will drive the rotor shaft 29 to rotate and make the rotor 23 move. The noise can be measured by the far-field microphone array measurement device 3. 16 wall microphones are synchronously arranged circumferentially in the front sound transmission measurement section and the rear sound transmission measurement section for sound mode identification. The silencer 12 is a sound-absorbing wedge with good sound absorption effect, which can meet the requirements of background noise, cutoff frequency and other aspects in the acoustic environment required for noise testing. There is no need to build a special test bench, the measurement is convenient and the measurement cost is low.

[0035] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A device for measuring the far-field directivity of fan noise, characterized by: The invention comprises an anechoic chamber (1), a single-stage low-speed fan device (2) and a far-field array microphone measurement device (3), wherein the anechoic chamber (1) comprises an anechoic chamber wall surface (11) and an anechoic member (12), wherein the anechoic member (12) is arranged in an array on the anechoic chamber wall surface (11), and the anechoic member (12) is a sound-absorbing wedge, an air intake bell mouth (21) is provided at one end of the single-stage low-speed fan device (2), a front sound lining casing section (22) is provided on the single-stage low-speed fan device (2), a rotor (23) is provided inside the single-stage low-speed fan device (2), and the single-stage low-speed fan device (2) is provided with a plurality of anechoic chambers. ) is provided with a stator casing (24), a stator is provided inside the stator casing (24), a rear sound lining casing section (25) is provided on the single-stage low-speed fan device (2), a rear support bearing frame (26) is provided on the single-stage low-speed fan device (2), a driving motor (27) is provided inside the single-stage low-speed fan device (2), an output end of the driving motor (27) is fixedly connected to a rotor shaft (29), and the other end of the rotor shaft (29) is fixedly connected to the center position of the rotor (23), and the far-field array microphone measurement device (3) is provided inside the anechoic chamber (1).

2. The device for measuring far-field directivity of fan noise according to claim 1, characterized in that: A load-bearing frame and a slide rail (28) are provided below the single-stage low-speed fan device (2).

3. The device for measuring far-field directivity of fan noise according to claim 2, characterized in that: The rotor (23) is a single-stage integral blade disk structure with 11 blades, which is integrally cast. The outer diameter of the rotor (23) is 406 mm, and the blade tip clearance is 2 mm.

4. The device for measuring far-field directivity of fan noise according to claim 3, characterized in that: The stator is a single-stage integral casting structure with 18 blades.

5. The device for measuring far-field directivity of fan noise according to claim 4, characterized in that: The stator casing (24) serves as the main load-bearing frame of the test bench and is fixedly connected to the front acoustic liner casing section (22) and the rear acoustic liner casing section (25) through flange stoppers. At the same time, 12 reinforcing ribs are designed between the front and rear flanges to ensure the rigidity of the load-bearing frame.

6. The device for measuring far-field directivity of fan noise according to claim 5, characterized in that: The front acoustic liner casing section (22) is used to install an acoustic liner for suppressing the forward noise of the fan in the circular duct, and can also be installed with a hard wall section for measuring the sound field in the rigid wall circular duct.

7. The device for measuring far-field directivity of fan noise according to claim 6, characterized in that: The rear acoustic liner casing section (25) adopts a split casing structure, which is convenient for installation and disassembly.

8. The device for measuring far-field directivity of fan noise according to claim 7, characterized in that: The rotor shaft (29) is simply supported at two points, with the front support point located at the inner ring of the stator casing (24) and the rear support point located at the inner ring of the rear support bearing frame (26).

9. The device for measuring far-field directivity of fan noise according to claim 8, characterized in that: The front end of the rotor shaft (29) is connected to the rotor (23) through a flange. The flange is plum blossom-shaped and convenient for installing the front fulcrum bearing cover. The rear end of the rotor shaft (29) is connected to the motor shaft through a coupling to achieve power transmission.

10. An application method of a device for measuring far-field directivity of fan noise, applicable to the device for measuring far-field directivity of fan noise according to any one of claims 1 to 9, characterized in that: include: S1. First, when measuring the far-field directivity of the fan noise, after the air intake bell mouth (21) enters the anechoic chamber (1), the driving motor (27) is operated to drive the rotor shaft (29) to rotate, and the rotation of the rotor shaft (29) causes the rotor (23) to move; When the S2 rotor (23) moves, the wind flow enters the anechoic chamber (1). The noise can be measured by a far-field array microphone measurement device (3). 21 far-field microphones are evenly distributed on a circular arc track 6150 mm away from the center of the fan, covering a radiation angle of 0°-180°. 16 wall microphones are synchronously arranged circumferentially on the front sound transmission measurement section and the rear sound transmission measurement section for acoustic mode identification. S3, the muffler (12) is a sound-absorbing wedge with good sound-absorbing effect, which can meet the requirements of the acoustic environment required for noise testing on background noise, cutoff frequency, etc., without the need to build a special test bench, and the measurement is convenient and the measurement cost is low.

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