A wind tunnel test method for EVTOL tilt-rotor aerodynamic noise

Abstract

A wind tunnel test method for aerodynamic noise of an EVTO tilt-rotor belongs to the technical field of wind tunnel test. In order to establish a wind tunnel test method for aerodynamic noise of an EVTO tilt-rotor, the present invention includes performing a hovering empty hub background noise test: rotating the rotor platform so that the rotor axis is perpendicular to the wind tunnel axis, performing an empty hub aerodynamic and noise test, and then performing aerodynamic data collection and noise data collection at various rotation speeds to obtain hovering empty hub background noise data; performing a tilt-rotor hovering noise test: installing the blades, setting the rotor axis to be perpendicular to the wind tunnel axis, and then performing aerodynamic data collection and noise data collection at various collective pitches and rotation speeds to obtain the tilt-rotor hovering noise data, which is corrected with the hovering empty hub background noise data to obtain the static pull and static power at various collective pitches and rotation speeds of the tilt-rotor hovering; performing a transition state and axial flow forward flight empty hub noise characteristic test: performing a transition state and axial flow forward flight tilt-rotor noise characteristic test.

Description

Technical Field

[0001] The invention belongs to the technical field of wind tunnel tests, and in particular relates to an EVTOL tiltrotor aerodynamic noise wind tunnel test method. Background Art

[0002] With the development of low-altitude economy, electric vertical take-off and landing aircraft (EVTOL) as a new means of transportation is gradually becoming a research hotspot for urban low-altitude aircraft. Among them, the distributed multi-tilt-rotor configuration realizes the conversion of lift and propulsion through the tilt-rotor, reduces the aerodynamic drag during level flight, and improves energy efficiency, making it an important representative configuration in the field of EVTOL. However, the typical flight conditions of EVTOL tilt-rotors are more complicated than those of traditional axial-flow propellers, including hovering, transition and forward flight states, which leads to complex aerodynamic and noise characteristics, making noise problems one of the key factors restricting the widespread application of EVTOL aircraft. Therefore, it is particularly important to carry out noise testing of EVTOL tilt-rotors. As an important means of noise testing, wind tunnel testing has the characteristics of stable test conditions and low price compared with flight testing. It is necessary to establish a wind tunnel test method for EVTOL tilt-rotor aerodynamic noise, deeply understand the noise generation mechanism, and thus provide technical support for EVTOL tilt-rotor design verification. Summary of the invention

[0003] The problem to be solved by the present invention is to establish an EVTOL tilt-rotor aerodynamic noise wind tunnel test method, and propose an EVTOL tilt-rotor aerodynamic noise wind tunnel test method.

[0004] To achieve the above object, the present invention is implemented through the following technical solutions:

[0005] An EVTOL tilt-rotor aerodynamic noise wind tunnel test method comprises the following steps:

[0006] S1. Conduct hovering empty hub background noise test: rotate the rotor platform so that the rotor axis is perpendicular to the wind tunnel axis, conduct empty hub aerodynamic and noise tests, and then collect aerodynamic data and noise data at various speeds to obtain hovering empty hub background noise data;

[0007] S2. Perform a tilt-rotor hovering noise test: install the blades, set the rotor axis to be perpendicular to the wind tunnel axis, and then collect aerodynamic data and noise data at each collective pitch and speed to obtain the tilt-rotor hovering noise data. Use the hovering empty hub background noise data obtained in step S1 to correct it, and obtain the static pull of the tilt-rotor hovering at each collective pitch and speed, and the static power of the tilt-rotor hovering at each collective pitch and speed;

[0008] S3. Conduct transition state and axial flow forward flight air hub noise characteristic tests: In the empty hub state, the lateral sideslip angle of the rotor platform is used instead of the longitudinal main shaft inclination angle of the rotor. The data acquisition system is used to collect the empty hub aerodynamic data and background noise data at different wind speeds and rotation speeds in the transition state test. The data acquisition system is used to collect the empty hub aerodynamic data and background noise data at different wind speeds and rotation speeds in the axial flow forward flight state test.

[0009] S4. Conduct transition state and axial flow forward flight tiltrotor noise characteristic tests: collect aerodynamic data of the transition state and axial flow forward flight state, and then subtract the aerodynamic data of the corresponding state of the empty hub obtained in step S3 to obtain the net aerodynamic force of the transition state and axial flow forward flight state after the empty hub is corrected.

[0010] Furthermore, the correction method in step S2 is to subtract the aerodynamic data of the empty hub in hovering from the aerodynamic data at each collective pitch and rotation speed in the tiltrotor hovering noise data.

[0011] Furthermore, the aerodynamic data collection method in steps S1-S4 is to collect aerodynamic data using azimuth synchronous triggering, and the noise data collection method is to use array sensors on an arc array for measurement. The arc array moves at equal intervals from upstream to downstream on one side of the wind tunnel, and collects noise data at each position.

[0012] Furthermore, the specific implementation method of step S4 includes the following steps:

[0013] S4.1. Change the lateral sideslip angle of the rotor platform instead of the longitudinal main axis inclination angle of the rotor to the initial tilt state;

[0014] S4.2. When the collective pitch is 0°, increase the rotor speed to the test speed, start the wind tunnel, and gradually increase the collective pitch as the wind speed increases. Monitor the rotor load in real time to ensure that the rotor thrust is positive and not greater than 50N.

[0015] S4.3. After reaching the initial wind speed, collect aerodynamic and noise data, increase the collective pitch in steps until the rotor power coefficient approaches or exceeds the power coefficient corresponding to the rotor drive motor power of the real aircraft, monitor the balance tension, torque, pitch moment and roll moment in real time to ensure that they are less than the balance design load, and collect aerodynamic and noise data at each collective pitch state;

[0016] S4.4. Change the rotor speed and repeat step S4.3 until the aerodynamic data and noise data are collected at all speeds;

[0017] S4.5. Change the test wind speed and repeat steps S4.3 and S4.4 until the aerodynamic data and noise data under all wind speed conditions are collected;

[0018] S4.6. Change the rotor platform to the next side slip angle, repeat steps S4.2 to S4.5, until the aerodynamic data and noise data collection under all transition state tests are completed, and the transition state tilt rotor aerodynamic data is calculated;

[0019] S4.7. Change the rotor platform sideslip angle to 0°, conduct a tiltrotor axial flow forward flight noise characteristic test, and repeat steps S4.2 to S4.5 until the aerodynamic data and noise data collection under all axial flow forward flight test conditions are completed;

[0020] S4.8. Calculate the aerodynamic data of the tiltrotor in the forward flight test state;

[0021] S4.9. When the wind tunnel is shut down, the collective pitch is gradually reduced to prevent excessive tension and torque overload. At the same time, the tension is kept at a small positive value. After the wind speed stabilizes, the collective pitch returns to zero and the rotor platform stops rotating.

[0022] S4.10. Perform empty hub correction on the transition state tiltrotor aerodynamic data collected in step S4.6 and the tiltrotor aerodynamic data in the forward flight test state collected in step S4.8 to obtain the net aerodynamic force in the transition state and axial flow forward flight state after the empty hub correction.

[0023] Furthermore, the method for the transition state tilt rotor aerodynamic data in step S4.6 is as follows:

[0024] For the array on the right side of the wind tunnel, the calculation formula for the counterclockwise rotation of the rotor platform when looking down is:

[0025] ;

[0026] in, They are the actual vertical force, pulling force, lateral force, pitch moment, rolling moment and yaw moment of the rotor hub and body axis. For torque balances to measure torque, is the nominal sideslip angle of the mechanism, is the rotor balance heading elastic angle, They are the actual vertical force, pulling force, lateral force, pitch moment, rolling moment and yaw moment of the rotor hub axis, is the actual rotor torque is the actual rotor axis inclination angle;

[0027] For the array on the left side of the wind tunnel, the calculation formula for the clockwise rotation of the rotor platform when viewed from above is:

[0028] .

[0029] Furthermore, the calculation formula for calculating the aerodynamic data of the tiltrotor in the forward flight test state in step S4.8 is:

[0030] .

[0031] Beneficial effects of the present invention:

[0032] The present invention discloses an EVTOL tilt-rotor aerodynamic noise wind tunnel test method, based on a traditional propeller test bench and a movable circular arc array, to propose an EVTOL tilt-rotor hover, transition and forward flight wind tunnel test method, which realizes hovering state measurement by changing the sideslip angle of the rotor platform to make the rotor axis perpendicular to the wind tunnel axis, and avoids the axial flow state rotor downwash inducing wind tunnel to generate wind speed, thereby reducing the rotor hovering efficiency; tilt-rotor transition state measurement is realized by changing the sideslip angle of the rotor platform instead of changing the tilt-rotor angle of attack, and through the movable circular arc array on one side of the wind tunnel, the measurement of the hovering rotor below, transition and forward flight rotor jump noise is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a flow chart for measuring the aerodynamic noise of a tiltrotor;

[0034] Figure 2 This is a schematic diagram of noise measurement for a tilt-rotor in hovering state;

[0035] Figure 3 This is a schematic diagram of the tiltrotor transition noise measurement;

[0036] Figure 4 This is a schematic diagram of the noise measurement of the tiltrotor in forward flight;

[0037] Figure 5 This is a schematic diagram of the circular array movement;

[0038] Figure 6 This is a three-dimensional schematic diagram of tiltrotor noise measurement;

[0039] Figure 7 This is a schematic diagram of the arrangement of the array microphone;

[0040] Among them, 1 is the wind tunnel contraction section, 2 is the arc array, 3 is the rotor platform, and 4 is the wind tunnel collector. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the specific embodiments described are only part of the embodiments of the present invention, rather than all of the specific embodiments. The components of the specific embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations, and the present invention can also have other embodiments.

[0042] Therefore, the following detailed description of the specific embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents the selected specific embodiments of the present invention. Based on the specific embodiments of the present invention, all other specific embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0043] In order to further understand the content, features and effects of the present invention, the following specific implementation methods are given as examples, and the attached Figure 1 -Attachment 7 is described in detail as follows:

[0044] Embodiment 1:

[0045] An EVTOL tilt-rotor aerodynamic noise wind tunnel test method comprises the following steps:

[0046] S1. Conduct hovering empty hub background noise test: rotate the rotor platform so that the rotor axis is perpendicular to the wind tunnel axis, conduct empty hub aerodynamic and noise tests, and then collect aerodynamic data and noise data at various speeds to obtain hovering empty hub background noise data;

[0047] Furthermore, the tilt-rotor test bench was prepared as follows before the test began:

[0048] Step 1. Complete the preparation of the tilt-rotor test bench balance system: measure the force and moment generated by the tilt-rotor through the rotor balance, and measure the torque generated by the tilt-rotor through the torque balance;

[0049] Step 2. Complete the control system preparation of the tilt-rotor test bench: ensure that the rotor collective pitch is continuously adjustable and the rotor platform sideslip angle is continuously adjustable;

[0050] Step 3. Complete the preparation of the tilt-rotor noise measurement array: the measurement array is a circular array, located on one side of the wind tunnel, and can move along the axis of the wind tunnel;

[0051] Step 4. Complete the preparation of the tilt-rotor data acquisition system and use the data acquisition system to synchronously collect performance and noise data;

[0052] Step 5. Complete the acoustic packaging of the tilt-rotor platform support and other airflow internal components.

[0053] Furthermore, the aerodynamic data collection method in steps S1-S4 is to collect aerodynamic data by using an azimuth synchronous triggering method, and the noise data collection method is to use an array sensor on an arc array for measurement, and the arc array moves from the upstream of the wind tunnel to the downstream at equal intervals on one side of the wind tunnel, and collects noise data at each position;

[0054] Furthermore, the aerodynamic data collection method uses azimuth synchronous triggering to collect performance data, collecting 80 circles, with no less than 64 points in each circle. The noise data is measured using an arc array. The arc array moves from 4.5 meters upstream of the hub center on one side of the wind tunnel to 4.5 meters downstream from the hub center, with an interval of 0.5 meters. Noise data is collected at each position. The collection time of the original noise data is not less than 10 seconds, and the collection frequency is not less than 2.56 times the upper limit of the frequency of concern.

[0055] Furthermore, the calculation method of aerodynamic noise is as follows:

[0056] ;

[0057] in, is the sound pressure level, is the effective sound pressure, is the reference sound pressure, Take 2×10 -5 Pa;

[0058] S2. Perform a tilt-rotor hovering noise test: install the blades, set the rotor axis to be perpendicular to the wind tunnel axis, and then collect aerodynamic data and noise data at each collective pitch and speed to obtain the tilt-rotor hovering noise data. Use the hovering empty hub background noise data obtained in step S1 to correct it, and obtain the static pull of the tilt-rotor hovering at each collective pitch and speed, and the static power of the tilt-rotor hovering at each collective pitch and speed;

[0059] Furthermore, the correction method in step S2 is to subtract the aerodynamic data of the empty hub in hovering from the aerodynamic data at each collective pitch and speed in the tiltrotor hovering noise data;

[0060] S3. Conduct transition state and axial flow forward flight air hub noise characteristic tests: In the empty hub state, the lateral sideslip angle of the rotor platform is used instead of the longitudinal main shaft inclination angle of the rotor. The data acquisition system is used to collect the empty hub aerodynamic data and background noise data at different wind speeds and rotation speeds in the transition state test. The data acquisition system is used to collect the empty hub aerodynamic data and background noise data at different wind speeds and rotation speeds in the axial flow forward flight state test.

[0061] S4. Conduct transition state and axial flow forward flight tiltrotor noise characteristic tests: collect aerodynamic data of the transition state and axial flow forward flight state, and then subtract the aerodynamic data of the corresponding state of the empty hub obtained in step S3 to obtain the net aerodynamic force of the transition state and axial flow forward flight state after the empty hub is corrected.

[0062] Furthermore, the specific implementation method of step S4 includes the following steps:

[0063] S4.1. Change the lateral sideslip angle of the rotor platform instead of the longitudinal main axis inclination angle of the rotor to the initial tilt state;

[0064] S4.2. When the collective pitch is 0°, increase the rotor speed to the test speed, start the wind tunnel, and gradually increase the collective pitch as the wind speed increases. Monitor the rotor load in real time to ensure that the rotor thrust is positive and not greater than 50N.

[0065] S4.3. After reaching the initial wind speed, collect aerodynamic and noise data, increase the collective pitch in steps until the rotor power coefficient approaches or exceeds the power coefficient corresponding to the rotor drive motor power of the real aircraft, monitor the balance tension, torque, pitch moment and roll moment in real time to ensure that they are less than the balance design load, and collect aerodynamic and noise data at each collective pitch state;

[0066] S4.4. Change the rotor speed and repeat step S4.3 until the aerodynamic data and noise data are collected at all speeds;

[0067] S4.5. Change the test wind speed and repeat steps S4.3 and S4.4 until the aerodynamic data and noise data under all wind speed conditions are collected;

[0068] S4.6. Change the rotor platform to the next side slip angle, repeat steps S4.2 to S4.5, until the aerodynamic data and noise data collection under all transition state tests are completed, and the transition state tilt rotor aerodynamic data is calculated;

[0069] Furthermore, the method for the transition state tilt rotor aerodynamic data in step S4.6 is as follows:

[0070] For the array on the right side of the wind tunnel, the calculation formula for the counterclockwise rotation of the rotor platform when looking down is:

[0071] ;

[0072] in, They are the actual vertical force, pulling force, lateral force, pitch moment, rolling moment and yaw moment of the rotor hub and body axis. For torque balances to measure torque, is the nominal sideslip angle of the mechanism, is the rotor balance heading elastic angle, They are the actual vertical force, pulling force, lateral force, pitch moment, rolling moment and yaw moment of the rotor hub axis, is the actual rotor torque is the actual rotor axis inclination angle;

[0073] For the array on the left side of the wind tunnel, the calculation formula for the clockwise rotation of the rotor platform when viewed from above is:

[0074] ;

[0075] S4.7. Change the rotor platform sideslip angle to 0°, conduct a tiltrotor axial flow forward flight noise characteristic test, and repeat steps S4.2 to S4.5 until the aerodynamic data and noise data collection under all axial flow forward flight test conditions are completed;

[0076] S4.8. Calculate the aerodynamic data of the tiltrotor in the forward flight test state;

[0077] Furthermore, the calculation formula for calculating the aerodynamic data of the tiltrotor in the forward flight test state in step S4.8 is:

[0078] ;

[0079] S4.9. When the wind tunnel is shut down, the collective pitch is gradually reduced to prevent excessive tension and torque overload. At the same time, the tension is kept at a small positive value. After the wind speed stabilizes, the collective pitch returns to zero and the rotor platform stops rotating.

[0080] S4.10. Perform empty hub correction on the transition state tiltrotor aerodynamic data collected in step S4.6 and the tiltrotor aerodynamic data in the forward flight test state collected in step S4.8 to obtain the net aerodynamic force in the transition state and axial flow forward flight state after the empty hub correction.

[0081] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0082] Although the present application has been described above with reference to specific embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, as long as there is no structural conflict, the various features in the specific embodiments disclosed in the present application may be used in combination with each other in any manner, and the fact that these combinations are not exhaustively described in this specification is only for the sake of omitting space and saving resources. Therefore, the present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An EVTOL tilt-rotor aerodynamic noise wind tunnel test method, characterized in that: The steps include: S1. Conduct hovering empty hub background noise test: rotate the rotor platform so that the rotor axis is perpendicular to the wind tunnel axis, conduct empty hub aerodynamic and noise tests, and then collect aerodynamic data and noise data at various speeds to obtain hovering empty hub background noise data; S2. Perform a tilt-rotor hovering noise test: install the blades, set the rotor axis to be perpendicular to the wind tunnel axis, and then collect aerodynamic data and noise data at each collective pitch and speed to obtain the tilt-rotor hovering noise data. Use the hovering empty hub background noise data obtained in step S1 to correct it, and obtain the static pull of the tilt-rotor hovering at each collective pitch and speed, and the static power of the tilt-rotor hovering at each collective pitch and speed; S3. Conduct transition state and axial flow forward flight air hub noise characteristic tests: In the empty hub state, the lateral sideslip angle of the rotor platform is used instead of the longitudinal main shaft inclination angle of the rotor. The data acquisition system is used to collect the empty hub aerodynamic data and background noise data at different wind speeds and rotation speeds in the transition state test. The data acquisition system is used to collect the empty hub aerodynamic data and background noise data at different wind speeds and rotation speeds in the axial flow forward flight state test. S4. Conduct transition state and axial flow forward flight tiltrotor noise characteristic tests: collect aerodynamic data of the transition state and axial flow forward flight state, and then subtract the aerodynamic data of the corresponding state of the empty hub obtained in step S3 to obtain the net aerodynamic force of the transition state and axial flow forward flight state after the empty hub is corrected.

2. The EVTOL tiltrotor aerodynamic noise wind tunnel test method according to claim 1, characterized in that: The correction method in step S2 is to subtract the aerodynamic data of the empty hub in hovering from the aerodynamic data at each collective pitch and rotation speed in the tilt-rotor hovering noise data.

3. The EVTOL tiltrotor aerodynamic noise wind tunnel test method according to claim 2, characterized in that: The aerodynamic data collection method in steps S1-S4 is to collect aerodynamic data using azimuth synchronous triggering, and the noise data collection method is to use array sensors on an arc array for measurement. The arc array moves at equal intervals from the upstream to the downstream of the wind tunnel on one side of the wind tunnel, and collects noise data at each position.

4. The EVTOL tiltrotor aerodynamic noise wind tunnel test method according to claim 3, characterized in that: The specific implementation method of step S4 includes the following steps: S4.

1. Change the lateral sideslip angle of the rotor platform instead of the longitudinal main axis inclination angle of the rotor to the initial tilt state; S4.

2. When the collective pitch is 0°, increase the rotor speed to the test speed, start the wind tunnel, and gradually increase the collective pitch as the wind speed increases. Monitor the rotor load in real time to ensure that the rotor thrust is positive and not greater than 50N. S4.

3. After reaching the initial wind speed, collect aerodynamic and noise data, increase the collective pitch in steps until the rotor power coefficient approaches or exceeds the power coefficient corresponding to the rotor drive motor power of the real aircraft, monitor the balance tension, torque, pitch moment and roll moment in real time to ensure that they are less than the balance design load, and collect aerodynamic and noise data at each collective pitch state; S4.

4. Change the rotor speed and repeat step S4.3 until the aerodynamic data and noise data are collected at all speeds; S4.

5. Change the test wind speed and repeat steps S4.3 and S4.4 until the aerodynamic data and noise data under all wind speed conditions are collected; S4.

6. Change the rotor platform to the next side slip angle, repeat steps S4.2 to S4.5, until the aerodynamic data and noise data collection under all transition state tests are completed, and the transition state tilt rotor aerodynamic data is calculated; S4.

7. Change the rotor platform sideslip angle to 0°, conduct a tiltrotor axial flow forward flight noise characteristic test, and repeat steps S4.2 to S4.5 until the aerodynamic data and noise data collection under all axial flow forward flight test conditions are completed; S4.

8. Calculate the aerodynamic data of the tiltrotor in the forward flight test state; S4.

9. When the wind tunnel is shut down, the collective pitch is gradually reduced to prevent excessive tension and torque overload. At the same time, the tension is kept at a small positive value. After the wind speed stabilizes, the collective pitch returns to zero and the rotor platform stops rotating. S4.

10. Perform empty hub correction on the transition state tiltrotor aerodynamic data collected in step S4.6 and the tiltrotor aerodynamic data in the forward flight test state collected in step S4.8 to obtain the net aerodynamic force in the transition state and axial flow forward flight state after the empty hub correction.

5. The EVTOL tiltrotor aerodynamic noise wind tunnel test method according to claim 4, characterized in that: The method for the transition state tilt rotor aerodynamic data in step S4.6 is as follows: For the array on the right side of the wind tunnel, the calculation formula for the counterclockwise rotation of the rotor platform when looking down is: ； in, They are the actual vertical force, pulling force, lateral force, pitch moment, rolling moment and yaw moment of the rotor hub and body axis. For torque balances to measure torque, is the nominal sideslip angle of the mechanism, is the rotor balance heading elastic angle, They are the actual vertical force, pulling force, lateral force, pitch moment, rolling moment and yaw moment of the rotor hub axis, is the actual rotor torque is the actual rotor axis inclination angle; For the array on the left side of the wind tunnel, the calculation formula for the clockwise rotation of the rotor platform when viewed from above is: 。 6. The EVTOL tiltrotor aerodynamic noise wind tunnel test method according to claim 5, characterized in that: The calculation formula for calculating the aerodynamic data of the tiltrotor in the forward flight test state in step S4.8 is: 。

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