JP3124128B2 - Low noise wind tunnel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a wind tunnel test facilities, especially the blower
The present invention relates to a low-noise wind tunnel with reduced noise generated from a source .

[0002]

Conventionally, as the noise reduction measures such as wind tunnel test equipment, sound absorption duct 01, as shown in FIG. 7, sound-absorbing splitter 02, a silencer of the sound absorbing shaped like sound absorption cell 03, a portion of the air feed path Was provided. However, in order to obtain a sufficient sound-absorbing effect with this type of sound-absorbing silencer, the overall length of the sound-absorbing duct must be sufficiently long, and the thickness and surface area of the sound-absorbing lining must be sufficiently large. Inevitably it had to grow. Also, since the silencer allows gas to pass through,
It was necessary to pay attention to the secondary noise caused by pressure loss and airflow.

[0003]

The above conventional wind tunnel equipment has the following problems to be solved.

[0004] That is, noise generated from the rotor blades of a blower used in a wind tunnel mainly includes rotating blade rotation sounds and broadband sounds. The rotating sound is a pure sound having a frequency of nΩZ _r (Hz) at the observation point if the rotor blades have the same pitch. Generally, the lower-order sound has higher acoustic energy. Where n
Each represents an arbitrary integer, Omega rotational frequency (Hz), Z _r is the rotor blade number. On the other hand, broadband sound is a wideband random sound generated by wake vortex outflow and upstream turbulence, and is a sound that is generated irregularly over a wide frequency range.

[0005] Of these noises, especially low-order rotating sounds may have a large acoustic energy, so that a conventional sound-absorbing silencer requires an extremely large silencer to achieve sufficient noise reduction. However, there is a problem that the sound cannot be sufficiently reduced due to a space problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides at least one set of a plurality of blowers arranged side by side on the same surface substantially perpendicular to the flow of a blower as a blower source.
Units corresponding to the reciprocal of the number of fans that make up the fan group
The rotor blade is attached to the rotor rotor with
Equipped with multiple blowers , a rotating pulse detector is provided on the motor-side stationary part of the blower, and a mark that can be detected by the rotating pulse detector is provided on the rotor blade rotor, so that the number of rotations and phase of the motor can be controlled. measuring the noise of the control device and the blower source to a monitor microphone, lower order rotational noise generated in the fan (pure tone having a frequency nΩZ _r (Hz))
By controlling each blower with the same rotation speed and maintaining the above-mentioned phase difference by the control device so that each of the blowers is canceled at the position of the monitor microphone for each blower group, low-order rotation noise is largely reduced. The purpose is to provide a low-noise wind tunnel.

[0007]

SUMMARY OF THE INVENTION The present invention aims to provide the following low-noise wind tunnel as means for solving the above-mentioned problems. Ri Na in parallel to the substantially same plane perpendicular to the plurality of fan that is rotated to the flow of the air by an electric motor, motion of the blower
The blades move with a pitch phase difference that is the reciprocal of the number of the blowers.
A pair of a blower unit that is attached to the wing rotor, a blowing source comprising in parallel to the substantially same plane perpendicular to the flow of the blowing one or more sets of the blowers group, rotation provided in the stationary portion of the motor a pulse detector, a mark provided on the rotor blade rotor to be detected by the rotation pulse detector, said electric motor and rotational speed as well as controllable control the phase of the provided downstream of the blowing source A low-noise wind tunnel comprising a monitor microphone for measuring noise of a blowing source.

[0008]

The present invention is configured as described above and has the following effects. For example, if the blower group consists of two blowers
In this case, each blower is approximately one-half pitch of
Attached to the rotor blade with a phase difference,
If the group consists of three fans, each fan must be
To provide a phase difference of approximately 1/3 pitch to the rotor blade rotor
Installed, for this purpose each control is
When the blowers in the fan group are rotated the same number of times, two blowers
In the group of blowers consisting of air blowers, each blower
It always rotates by one pitch with a phase difference and is at the observation point.
Therefore, low-order rotation sounds are almost the same amplitude and opposite phase
Each other cancel each other, and consist of three blowers
In a group of blowers, each blower is approximately 1/3 pitch of the rotor blade
Rotation with a phase difference always
The transpositions are almost the same amplitude and are out of phase by approximately 120 °
Sound and cancel each other out, especially the blower
Among the noises that occur, low-order rotation noise can be reduced.
In other words, the pitch of the blades attached to the rotor
The pitch is the reciprocal 1 / n of the number n of the blowers that make up the airplane group
By attaching the rotor to the rotor with
At the observation point, the low-order rotation sounds
Sounds of opposite phase in width cancel each other out and greatly reduce sound
can do. In addition, a rotation pulse detector is provided on the motor-side stationary part of the blower, and a mark that can be detected is provided on the rotor blade rotor, and a control device that can control the rotation speed and phase of the motor, and measures the noise of the blower source because comprising a monitor microphone for low-order rotation noise produced in each blower (pure tone having a frequency nΩZ _r (Hz)), so that each cancel at the location of the monitor microphone for each fan group, the blower by the controller Can be operated at the same rotation speed and while maintaining the phase difference of the mounting pitch of the moving blades mounted on the moving blade rotor . Therefore, the blower having such a configuration can significantly reduce low-order rotation noise among the noises generated by the blower.

[0009]

Examples of low-noise wind tunnel EXAMPLES The invention will be described with reference to Figures 1-6.

FIG . 1 shows a low-noise wind as an embodiment of the present invention.
FIG. 2 is a side view of the tunnel, and FIG.
FIG. 3 is an example of a blower and the like constituting the blow source shown in FIG.
FIG. 3 (a) is a diagram showing a normal state without the control device.
3 (b) is a side view, and FIG. 4 is a control apparatus of FIG.
FIG. 5 is an explanatory view of the phase difference adjustment in FIG.
FIG. 6 is an exploded view showing another example of the blower to be formed, and FIG.
The qualitative noise level reduction effect of the blower shown in Fig. 5
Noise levels of these fans and conventional fans to show
FIG.

In the low-noise wind tunnel of this embodiment shown in FIG .
It is blown to the right side of the figure by the wind source 1 and passed through the rectifier 5 to be anechoic
The wind is sent into the measurement chamber 6. In addition, blast source 1
A sound absorbing material 7 is installed on the inner wall of the pipe between the
I have. In a low-noise wind tunnel configured in this way, anechoic measurement
The noise level of the chamber 6 can be kept low
It is possible to measure not only aerodynamic characteristics but also aerodynamic noise characteristics.
You. In FIG. 1, 15 is provided downstream of the air supply source 1.
Monitor microphone for measuring the noise of
Reference numeral 6 denotes a sound level meter for measuring the level of the noise of the air supply source 1.

In FIG. 2, reference numeral 1 denotes the air blower 4
To the same plane almost perpendicular to the direction of flow
An air supply source in which six blowers 4 are arranged in parallel on a parallel surface, and 2
The rotor blade 3 of the blower 4 is a rotor blade of the rotor rotor 2.
You. The blower 4 has nine blades 3 at a pitch p as shown in the drawing.
FIG. 5 is an exploded view of the rotor blade 2 provided around the central axis.
As shown in the figure, on the front side of the electric motor 8 in (a),
In the posture shown in (b) or (c), the key 10 of the rotor 9 is
The keyway 11 is engaged and fixed, but the rotor 9
And the rotor blade 2 may be integrally formed.

Next, the operation of the above configuration will be described.

[0014] That is, as shown in FIG. 2, the low Noise of this embodiment
A plurality of blower 4 constituting the blast source of the sound wind tunnel are disposed on the same plane, but the blowing source 1 is configured, the blowing source
In the case of 1 , since the number of the blowers 4 is six in total, either combination of three sets of the blowers including two blowers 4 or two sets of the blowers including three blowers 4 is possible.
In FIG. 2 , the upper and lower two blowers 4 constitute a blower group, and the description will be made.
Blower group 3 using blower 4 shown in FIG. 5 for simplification
The case where a set is used will be described. In the figure, p indicates the pitch of the moving blades 3, and θ _{1 to} θ ₆ indicate the angle between the reference position of the rotor 9 of each electric motor 8 and the reference moving blade a of each moving blade rotor 2.

, VI are arranged on the same plane.
The number for convenience of each blower 4 is shown. As shown in Figure 2
As described above, first, the blowers I and II constituting one blower group are formed by combining the rotor 9 of the electric motor 8 and the rotor blade 2 such that | θ ₁ −θ ₂ | = p / 2 is satisfied.
It is standing up. Similarly, blowers III and IV are assembled so that | θ ₃ −θ ₄ | = p / 2 , and blowers V and VI are assembled so as to satisfy | θ ₅ −θ ₆ | = p / 2 .

As described above, the moving blades 3 of the blowers 4 of the blower group shown in FIG. 5 are assembled so as to be shifted from each other by a predetermined angle , so that the rotor 9 of the electric motor 8 has a reference position. are you in so that the key 10 is provided to. Also, blades rotor 2 can angle θ management of the reference rotor blade a and the key groove 11 of the moving blade 3, constituting the blower unit as shown in FIG. 5 (b), each blade of the (c) in 3, | θ _a -θ _B |
The can be set to a predetermined angle, | positive to p / 2 | θ _A -θ _B
It can be shall be set to sure. That is,
Of the pitch p of the rotor blades 3 between the blowers 4 which is the main part of
Means that the number of blowers 4 constituting one set of blowers is two
In the case of, three fields are shifted from each other by 1/2 pitch.
In the case, it can be configured to be shifted by 1/3 pitch.
ing.

Thus, in the blower 4 shown in FIG.
Is a key 10 on the motor 8 side and a keyway 11 on the rotor blade rotor 2 side.
Satisfies 1/2, 1/3 pitch respectively
It was configured as follows. However, like this, key 10 and key
Determine the relationship with groove 11 to 1/2, 1/3 pitch
Between the rotor blades 2 of 1/2 pitch and 1/3 pitch
Does not lose compatibility, for example, the blower group of blower source 1
Change the number of blowers 4 from 2 to 3 or from 3 to 2
If you want to change it, the result is about 50-70% waste
Will happen. Also, no matter how high the accuracy,
Errors are inevitable. For example, the twist angle, pitch,
Minor errors such as the keyway position (angle with respect to the reference position)
Accumulation does not produce the intended phase shift and cancels the rotating sound.
May not be achieved sufficiently.

To solve such a problem at once
Prepares an appropriate number of rotor blade rotors 2 having no keyway 11,
For example, the rotor rotor 2 and the rotor 9 of the electric motor 8 are nuts
Or by tightening friction with the rotor 9
Taper to prevent axial force from nuts and other means.
Accordingly, the shaft hole on the rotor blade rotor 2 side and the rotor 9 are tightly fitted.
As a result, the rotor blade rotor 2 with respect to the rotor 9
It is conceivable to adopt a configuration that can adjust continuously in the rotation direction.
It is. However, even in this case,
Minor errors such as the twist angle, pitch, position of keyway, etc. of the rotor blade 3
The difference in pitch between the moving blades 3 that has accumulated the difference is
To 1/2 or 1/3 depending on the number of machines 4,
So that low-order rotation noise can be greatly reduced
I have.

The number of the blowers 4 constituting the blower group
The rotation pulse detector 13 and the mark 1
2, each blade row corresponding to the phase difference between the blowers 4
Temporary installation of the wind turbine 2 and trial run of the low noise wind tunnel shown in Fig. 1.
Therefore, noise is monitored by the monitor microphone 15 and the sound level meter 16 described later.
Check the level of sound reduction and if not, follow the above process
Repeatedly, when the noise reached the lowest level,
That is, a suitable pitch shift of the moving blade 3 determined by the number of the blowers 4
, The blade rotor 2, for example, the nut
Fully tightened (tightened with regular torque) for full mounting
It is. Thus, in the present embodiment, the rotor blade 2
And the rotor 9 are set by the keyway 11
Pitch setting of the moving blade
The method is not limited.

[0020] Thus, the theta ₁ through? ₆ shown in FIG. 2 described above
The final value is slightly different in this embodiment.
This difference is also caused by the control device
And so on.

Next, based on FIG. 3, one set of transmission of this embodiment will be described.
Control of the pitch p of the rotor blades 3 between the blowers 4 constituting the fan group
Will be described. In the figure, 12 is a moving blade of the blower 4
A mark provided on the rotor 2 for detecting a rotation pulse, 1
3 is a rotary pulse detector provided at a stationary portion of the electric motor 8,
14 is a control device for controlling the rotation speed and phase of the electric motor 8.
And 15 are provided at the downstream of the air source 1,
A monitor microphone for measuring sound, and 16 is a noise
It is a sound level meter that measures sound.

Next, the operation of the above configuration will be described.

First, a blower constituting one blower group
I and II show the low-order rotation noise generated by each blower 4 in FIG.
Cancel each other at the position of the monitor microphone 15 and the result
3 so that the indicated value of the sound level meter 16 becomes small.
The position between the moving blades 3 by means of the blower 4
The phase difference is adjusted. Similarly, blowers III and IV as well as blowers
The phase difference between the moving blades 3 of the wind turbines V and VI was also adjusted.
It is.

FIG . 4 is a perspective view of the rotor blade 3 between the blowers 4 described above.
Switch blades 3 of the blower 4 of the blower group
FIG. 4 is an explanatory diagram for operating while maintaining a proper phase difference.
That is, the rotation pulse detector 13 is attached to the stationary portion of the motor 8.
It is installed and the reference moving blade a is selected from the moving blades 3 in the moving rotor 2.
And the rotation pulse detector 13 can detect this portion
A mark 12 is provided. With the blower 4 configured in this way
Is the rotation speed Ω (Hz) of the rotor blade 3 as shown in FIG.
Rotation pulse at an interval of period T (= 1 / Ω) (sec)
Is detected. Therefore, the rotor 3 of one blower 4 is used as a reference.
The rotor blades 3 of the other blower 4 are shown in FIGS.
As shown, a time difference Δt occurs between the mutual rotation pulses.
Then, the control devices 14 of the respective electric motors 8 are adjusted. this
In this manner , each blade 3 has an appropriate phase difference Δθ (= 2π
Δt / T) (rad)
You.

In this embodiment, the number of blowers in the blower group is
Although the description has been given with two examples, the number of blowers constituting the blower group is
The number is not limited to two and deviates from the purpose of the invention
The number may be two or more and any number within a range not to be performed. Moving blade low
Setting of the rotor 2 and the rotor 9 by tightening with nuts etc.
, The pitch of the rotor blades between each blower is continuously variable.
So that it can be adjusted by the keyway 11
In addition to the effect of the blower, there is no limit on the number of blowers in the blower group
There is an advantage of not receiving. Also, the rotor blade 2 is keyed.
-Procurement because there is no groove 11 etc. and they are completely common to each other
Another advantage is that the quantity and spare parts can be significantly reduced.
There is also the advantage that the equipment can be obtained at low cost.
You.

In addition, the use of a monitor microphone and a sound level meter
And finally the lowest noise level is obtained.
The shape accuracy can be relaxed, and the defect rate can be reduced accordingly,
This has the advantage of reducing the cost.

As described above, according to this embodiment, the wind tunnel
Selection of the number of blowers of the wind source and the
By adjusting the deviation, low-order rotation noise is canceled
As a result, a wind tunnel with significantly lower noise compared to the conventional example can be obtained.
There is an advantage.

[0028]

The present invention is configured as described above.
Has the effect of

That is, according to the present invention, the wind tunnel test device
Noise radiated from the outlet, and low-order noise that is difficult to silence
The noise of a building without using a large silencer
Can be. Therefore, the background noise level at the aerodynamic characteristic measurement position
Aerodynamic noise measurement is compact because it can be greatly reduced
Can be realized with simple equipment.

[Brief description of the drawings]

FIG. 1 is a side view of a low noise wind tunnel according to the present invention;

FIG. 2 is a front view of a blowing source of the low noise wind tunnel shown in FIG . 1 ;

FIG. 3 is a view of a blower and the like of a blow source shown in FIG . 2;
Front view, (b) side view ,

FIG. 4 is a view showing a rotation device between blowers by a control device shown in FIG . 3;
Explanatory diagram of Luz phase difference adjustment ,

FIG. 5 shows another example of the blower constituting the blower shown in FIG .
Exploded view, (a) is a front view of the motor, (b) is a rotor blade low
(C) is a rotor blade with a ピ ッ チ pitch shifted attitude.
Positive side view of the over data,

FIG. 6 shows a qualitative noise in the blower shown in FIG . 3 or FIG.
Comparison diagram with the conventional example showing the sound level reduction effect,

FIG. 7 is a perspective view of various examples of a conventional silencer and the like.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 blower source 2 rotor blade 3 rotor blade 4 blower 5 rectifier 6 anechoic measurement chamber 7 sound absorbing material 8 motor 9 rotor 10 key 11 key groove 12 mark 13 rotation pulse detector 14 control device 15 monitor microphone 16 noise meter

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shigeru Takagi 5-717-1 Fukahoricho, Nagasaki-shi, Nagasaki Research Laboratory, Mitsubishi Heavy Industries, Ltd. (56) References JP-A-2-119612 (JP, A) (58) ) Surveyed field (Int.Cl. ⁷ , DB name) G01M 9/04

Claims (1)

(57) [Claims] 1. A Ri Na in parallel to the substantially same plane perpendicular to the plurality of fan that is rotated to the flow of the air by an electric motor, feeding each
The rotor blades of the blower have a pitch phase difference that is the reciprocal of the number of the blowers.
And a pair of blowers groups that are attached to the rotor blade rotor is, a blower source comprising in parallel to the substantially same plane perpendicular to the flow of the blowing one or more sets of the blowers group, provided in the stationary portion of the motor a rotation pulse detector has been, and mark provided on the detectably above rotor blade rotor by the rotation pulse detector, upper
Serial and motor speed as well as controllable control the phase of the low-noise wind tunnel, characterized by comprising; and a monitor microphone for measuring the noise of the blast source provided downstream of the blowing source.