JP3603088B2 - Acoustic test equipment and jet nozzle used for it - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an acoustic test facility for an aircraft, a rocket, and the like, and a jet nozzle used for the facility.
[0002]
[Prior art]
For example, when launching or flying a rocket, strong noise is generated from around the engine and the airframe, affecting the onboard satellites and the like. Therefore, an acoustic test facility is used in advance to create an acoustic environment close to the actual environment on the ground, and to examine whether artificial satellites and the like can withstand the acoustics and what kind of vibration occurs.
[0003]
The outline of the acoustic test equipment will be described with reference to FIG. 14. Reference numeral 1 denotes a reverberation room in which a diffused sound field is created and a specimen 2 such as an artificial satellite is placed. A loading carriage 3 that moves inward is provided. Reference numeral 4 denotes an acoustic converter for generating a sound pressure spectrum of a high-frequency component in the reverberation room 1, and reference numeral 5 denotes an air pressure generator for supplying compressed air to the acoustic converter 4 through a compressed air supply path 6, and is driven by an electric motor 7. And a compressor 8. Reference numeral 9 denotes an acoustic control device for controlling the sound pressure spectrum level in the reverberation room 1, comprising a computer 10 and a signal generator 11 controlled by the computer 10. 10 and controls the signal generator 11 based on the sound pressure signal to generate a signal. The signal is amplified by the amplifier 13 and sent to the acoustic converter 4 as a drive signal. The sound pressure spectrum of the high-frequency component generated in the reverberation chamber 1 is controlled by controlling the flow rate of the compressed air ejected from the 14 to the horn 15.
[0004]
The acoustic transducer 4 for controlling the flow rate of compressed air ejected from the air chamber 14 to the horn 15 has a fixed slit 16 provided at the base end of the horn 15 as shown in FIG. A movable slit 17 is provided in the chamber 14 so as to be able to move up and down, and the movable slit 17 is moved up and down by an electric signal as a drive signal from the amplifier 13, and the opening area of the fixed slit 16 is changed. It emits compressed air to generate sound. FIG. 16 shows a state in which when the electric signal V = V ₁ at t ₁ , the movable slit 17 rises to the maximum and coincides with the fixed slit 16, and the fixed slit 16 is fully opened to maximize the compressed air flow rate. Show. FIG. 17 shows a state in which when the electric signal V = V ₂ = 0 at t ₂ , the movable slit 17 is lowered, the fixed slit 16 is half closed, and the compressed air flow rate is reduced by half. 18, when the electric signal V = V ₃ at t _3, the movable slit 17 is maximally lowered, showing a state where the fixed slit 16 is compressed air flow is completely closed becomes only a slight leak.
[0005]
By the way, the high frequency range that can be controlled by the acoustic transducer 4 used as the sound source of the acoustic test equipment is 1.25 KHz at the maximum, and the frequency component required for the acoustic test up to 10 KHz is high frequency up to 1.25 KHz. The test has been performed by expanding the permissible range of the target sound pressure spectrum level for the acoustic spectrum in a high frequency range. Therefore, the accuracy of an acoustic test that required generation of a frequency component up to 10 KHz was not satisfactory.
[0006]
[Problems to be solved by the invention]
Therefore, the present invention is to provide an acoustic test facility improved so as to be able to generate a high frequency sound that cannot be covered by an acoustic transducer with high power and automatically controlled, and a jet nozzle used for the same. Things.
[0007]
[Means for Solving the Problems]
An acoustic test facility according to the present invention for solving the above-mentioned problems comprises an echo chamber in which a diffuse sound field is created and a specimen is placed, an acoustic transducer for generating a sound pressure spectrum of a high-frequency component in the echo chamber, An air pressure generator that supplies compressed air to the transducer, and the sound pressure of the reverberation room is taken into a computer, and a signal generator is controlled based on the air pressure to generate a signal. This signal is amplified and driven to the acoustic transducer. An acoustic test equipment comprising a signal, a sound control device for controlling the flow rate of compressed air ejected into the reverberation chamber and controlling a sound pressure spectrum of a high-frequency component generated in the reverberation chamber. A high-pressure air ejection device is provided for branching the supplied compressed air in a branch passage and ejecting the jetted air as a jet stream into the reverberation chamber, and the acoustic air is provided in a branch of the compressed air to the high-pressure air ejection device. By comprising providing a pressure regulating valve opening is controlled by a control signal from the computer of the control device is intended, characterized.
[0008]
The jet nozzle of the present invention is used for a high-pressure air ejection device in the acoustic test equipment, and is provided at a tip of a branch where compressed air is supplied in the reverberation chamber, and ejects compressed air into the reverberation chamber. This is characterized in that it is configured to narrow down immediately before performing.
[0009]
The jet nozzle according to the present invention includes a jet nozzle that is bent into a crank shape in two steps, an jet nozzle that is bent into an L shape and a spoiler is provided inside the vicinity of the tip opening, and a tapered nozzle body disposed on one side. In contrast to this, a barrier plate is arranged on the other side to prevent obstruction of the jet flow to be ejected, and a jet nozzle ejected by attaching a tapered nozzle body to oppose to collide with the jet flow There is. Various sizes of the tapered nozzle body are prepared so that the diameter of the nozzle body can be changed and the interval between the nozzle body and the opposed nozzle body can be changed.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of an acoustic test facility of the present invention and a jet nozzle used for the same will be described. First, the acoustic test facility will be described with reference to FIG. 1. This acoustic test facility is an improvement of the conventional acoustic test facility described with reference to FIG. 9, and the same components in FIG. The description is omitted. The improved portion will be described. High-pressure air jetting in which compressed air supplied from the air pressure generating device 5 to the acoustic transducer 4 through the compressed air supply channel 6 is branched at the branch channel 18 and jetted into the echo chamber 1 as a jet stream. In addition to the device 19, a pressure regulating valve 20 whose opening is controlled by a control signal from the computer 10 of the acoustic control device 9 is provided in the branch 18 of the compressed air to the high-pressure air ejection device 19.
[0011]
A jet nozzle is used for the high-pressure air ejection device 19 in the acoustic test facility of the present invention. The jet nozzle is provided in the reverberation chamber 1 and is provided at the tip of a branch 18 to which compressed air is supplied. In the following, various specific examples of the jet nozzle will be described with reference to the drawings. The jet nozzle 21 shown in FIG. And a square pipe 22 which is bent into a crank shape in two stages in the reverberation room 1. The jet nozzle 23 shown in FIG. 3 is configured such that a spoiler 26 is provided inside the vicinity of a distal end opening 25 of a square pipe 24 bent into an L shape in the reverberation chamber 1. The jet nozzle 27 shown in FIG. 4 is detachably attached to the tip of a U-shaped tube 30 which connects a tapered nozzle body 28 to one side of a manifold 29 connected to the tip of the branch passage 18 in the echo chamber 1. A stop plate 31 is disposed on the other side of the nozzle body 28 so as to oppose the nozzle body 28 so as to obstruct the jet flow to be jetted. The jet nozzle 32 shown in FIG. 5 is configured such that, in the reverberation chamber 1, the tip ends of U-shaped tubes 30, 30 for connecting the opposed tapered nozzle bodies 33, 33 to both sides of the manifold 29 connected to the tip of the branch passage 18. , Which is detachably mounted on the nosepiece so as to collide with the jet stream to be ejected. The tapered nozzle body 28 and the nozzle bodies 33, 33 are prepared in various sizes so that the diameters thereof can be changed, and the gaps between the opposing stop plate 31 and the nozzle body 33 can be changed.
[0012]
In the acoustic test equipment of the present invention configured as shown in FIG. 1, a sound source in a high frequency range up to about 1.25 KHz can be obtained by controlling the sound transducer 4 in the same manner as in the related art. Is obtained by strong sound generated by a jet stream ejected from the jet nozzle of the high-pressure air ejection device 19 into the echo chamber 1. The performance test of the jet nozzle 21 shown in FIG. 2, the jet nozzle 23 shown in FIG. 3, the jet nozzle 27 shown in FIG. 4, and the jet nozzle 32 shown in FIG. 5 in the high-pressure air jet device 19 is shown in FIG. Shown in the graph. As can be seen from this graph, each jet nozzle exceeded 100 dB in a high frequency range exceeding 1.25 KHz, and was able to obtain a strong sound of 124 to 134 dB near 10 KHz. The control of the acoustic spectrum in the high frequency range by the jet nozzle of the high-pressure air jet device 19 of the acoustic test equipment is linked with the computer control of the acoustic transducer 4, that is, the acoustic spectrum is controlled in advance by the computer 10 of the acoustic control device 9. The opening degree of the pressure regulating valve 20 is controlled by a control signal based on the set band frequency, and thereby the acoustic spectrum is automatically adjusted. An outline of the automatic control of the acoustic spectrum in the high frequency range by the jet nozzle is shown in the flowchart of FIG.
[0013]
However, when the jet nozzle of the high-pressure air jet device 19 of the acoustic test equipment is the jet nozzle 27 shown in FIG. 4, a nozzle body 28 having a different diameter can be used, or a nozzle body having a different length that can change the distance from the stop plate 31 can be used. In the case of the jet nozzle 32 shown in FIG. 5, the nozzle bodies 33 having different diameters can be used, or the nozzle bodies 33 having different lengths can change the interval between the opposed nozzle bodies 33. , 33, the required frequency can be controlled. The sound pressure level can be controlled by adjusting the supply pressure of the compressed air to each jet nozzle. FIG. 8 is a graph showing acoustic characteristics when the sound pressure level is controlled by adjusting the supply pressure of the compressed air in the jet nozzle 32 of FIG.
[0014]
In the jet nozzle 21 of FIG. 2, a shutter 34 is provided slidably up and down near the nozzle outlet as shown in FIG. 9 and this shutter 34 is moved up and down by an actuator 35. It can be adjusted arbitrarily and the required frequency can be easily controlled. Further, in the jet nozzle 23 shown in FIG. 3, a shutter 34 is provided so as to be horizontally slidable back to back with the spoiler 26, and the shutter 34 is horizontally moved by an actuator 35 as shown in FIG. The area can be arbitrarily adjusted, and the required frequency can be easily controlled. Further, in the jet nozzle 27 of FIG. 4 and the jet nozzle 32 of FIG. 5, near the outlet of the tapered nozzle main body 28 and the nozzle main bodies 33, 33, a shutter 36 of a type equipped with a camera as shown in FIG. If the opening of the shutter 36 is adjusted by an actuator (not shown), the exit cross-sectional areas of the nozzle body 28 and the nozzle bodies 33, 33 can be arbitrarily adjusted, and the required frequency can be easily controlled. In the jet nozzle 27 shown in FIG. 4 and the jet nozzle 32 shown in FIG. 5, the tapered nozzle body 28 and one of the nozzle bodies 33 are made slidable as shown in FIG. When the nozzle length is adjusted by moving the nozzle back and forth by 37, the interval between the nozzle body 28 and the opposing stop plate 31 can be arbitrarily changed, and the interval between the nozzle body 33 and the opposing nozzle body 33 can be arbitrarily adjusted. Thus, the required frequency can be easily controlled. As shown in FIG. 12, a camera as shown in FIG. 11 is provided near the outlet of the slidable tapered nozzle body 28 and the nozzle body 33 (in this case, both of the opposed nozzle bodies 33, 33). When the opening degree of the shutter 36 is adjusted by an actuator (not shown), the exit cross-sectional areas of the nozzle body 28 and the nozzle bodies 33, 33 can be arbitrarily adjusted. In addition to being able to arbitrarily change the distance between the nozzle and the nozzle body 33, the required frequency can be easily controlled with higher accuracy. Although the number of the shutters 34 shown in FIG. 9 is one, two L-shaped shutters 38 as shown in FIG. 13 or three or more shutters of an appropriate shape may be used. In the case of the jet nozzle 27 shown in FIG. 4 and the jet nozzle 32 shown in FIG. 5, since the cross section is circular, a camera as shown in FIG. Although a shutter 36 of a model type is provided, when the jet nozzle 27 and the jet nozzle 32 are square in cross section, a shutter 34 as shown in FIG. 9 or an L-shaped shutter 38 as shown in FIG. 13 may be used. Three or more shutters having a shape may be used.
[0015]
【The invention's effect】
As can be seen from the above description, according to the acoustic test equipment of the present invention, an acoustic spectrum in a high frequency range of 1.25 KHz or more, which could not be covered by the conventional acoustic transducer, can be generated by the high-pressure air ejection device. An accurate acoustic test can be performed. Further, the acoustic test equipment of the present invention automatically adjusts the acoustic spectrum in the high frequency range by controlling the supply amount and the supply pressure of the compressed air to the high-pressure air ejection device in conjunction with the computer control of the acoustic transducer. Therefore, it is possible to prevent an artificial control error and improve operability. Further, the acoustic test equipment of the present invention includes a high-pressure air ejection device for branching compressed air supplied to the acoustic transducer and ejecting the compressed air as a jet stream into the reverberation chamber without significantly modifying the conventional acoustic test equipment. It can be obtained simply by providing a compressed air pressure regulating valve whose opening is controlled in conjunction with computer control of the vessel, so that the problems of the conventional acoustic test equipment can be solved at low cost.
[0016]
The jet nozzle of the present invention used in the high-pressure air ejection device of the acoustic test equipment is configured to be narrowed immediately before ejecting the compressed air in the reverberation chamber, so that the compressed air is ejected as a jet stream, and from the jet stream, By generating strong sound, a sound source in a high frequency range can be obtained. In particular, a jet nozzle that has a tapered nozzle body on one side and a blocking plate on the other side to oppose it so as to obstruct the jet flow to be ejected, or a nozzle body that is tapered opposite to each other In the case of a jet nozzle that causes a jet stream to be ejected to collide with a jet nozzle, the required frequency can be controlled by changing the diameter of the tapered nozzle body or changing the interval between the nozzle body and the opposing one. . In the case where the cross-sectional area of the nozzle outlet can be adjusted arbitrarily or the length of the nozzle can be arbitrarily adjusted so that the distance between the nozzle and the opposing nozzle can be arbitrarily changed, it is necessary. The frequency can be easily controlled, and particularly in the case where both the cross-sectional area of the nozzle outlet and the nozzle length can be arbitrarily adjusted, the required frequency can be easily and precisely controlled.
[Brief description of the drawings]
FIG. 1 is a diagram showing an outline of an acoustic test facility of the present invention.
FIG. 2 is a perspective view showing an example of a jet nozzle used in a high-pressure air ejection device of the acoustic test equipment of the present invention.
FIG. 3 is a perspective view showing another example of the jet nozzle used in the high-pressure air ejection device of the acoustic test equipment of the present invention.
FIG. 4 is a perspective view showing still another example of the jet nozzle used in the high-pressure air ejection device of the acoustic test equipment of the present invention.
FIG. 5 is a plan view showing another example of the jet nozzle used in the high-pressure air ejection device of the acoustic test equipment of the present invention.
FIG. 6 is a graph showing performance test results of each jet nozzle shown in FIGS. 2 to 5;
FIG. 7 is a flowchart showing an outline of automatic control of an acoustic spectrum in a high frequency range by a jet nozzle.
8 is a graph showing acoustic characteristics when the sound pressure level is controlled by adjusting the supply pressure of compressed air in the jet nozzle of FIG.
FIG. 9 is a perspective view showing a modified example of the jet nozzle of FIG. 2;
FIG. 10 is a perspective view showing a modified example of the jet nozzle of FIG.
FIG. 11 is a front view of a shutter provided near an outlet of a tapered nozzle body in the jet nozzle of FIGS. 4 and 5;
FIG. 12 is a plan view showing a modified example of the tapered nozzle body in the jet nozzle of FIGS. 4 and 5;
FIG. 13 is a front view showing a modified example of the shutter in the jet nozzle of FIG. 9;
FIG. 14 is a diagram showing an outline of a conventional acoustic test facility.
FIG. 15 is a system diagram of an acoustic transducer in an acoustic test facility.
FIG. 16 is a schematic diagram showing a state in which the movable slit and the fixed slit of the acoustic transducer of FIG. 10 coincide with each other and the fixed slit is fully opened to maximize the compressed air flow rate.
FIG. 17 is a schematic diagram showing a state where the movable slit of the acoustic transducer of FIG. 10 is lowered, the fixed slit is half closed, and the compressed air flow rate is reduced by half.
FIG. 18 is a schematic view showing a state in which the movable slit of the acoustic transducer of FIG. 10 is lowered to the maximum and the fixed slit is fully closed, so that the compressed air flow is only slightly leaked.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 reverberation room 2 specimen 3 carry-in trolley 4 acoustic transducer 5 air pressure generator 6 compressed air supply path 7 motor 8 compressor 9 acoustic controller 10 computer 11 signal generator 12 microphone 13 amplifier 14 air chamber 15 horn 16 fixing slit 17 Movable slit 18 Branch path 19 High-pressure air jetting device 20 Pressure regulating valve 21 Jet nozzle 22 Square pipe 23 Jet nozzle 24 Square pipe 25 Tip opening 26 Spoiler 27 Jet nozzle 28 Tapered nozzle body 29 Manifold 30 U-shaped pipe 31 Stopper plate 32 Jet nozzle 33 Tapered nozzle body 34, 36 Shutter 35, 37 Actuator 38 L-type shutter

Claims (12)

A reverberation chamber in which a diffused sound field is created and a specimen is placed, an acoustic transducer for generating a sound pressure spectrum of a high-frequency component in the reverberation chamber, an air pressure generator for supplying compressed air to the acoustic transducer, and a reverberation chamber The sound pressure is taken into the computer to control the signal generator to generate a signal based thereon, amplify this signal and send it to the acoustic transducer as a drive signal, and control the flow rate of compressed air ejected to the reverberation chamber. And a sound control device for controlling a sound pressure spectrum of a high-frequency component generated in the reverberation chamber. A high-pressure air ejection device that ejects the jet air as a jet stream, and the opening is controlled by a control signal from a computer of the acoustic control device in the middle of the branch of the compressed air to the high-pressure air ejection device. Acoustic test equipment, characterized by comprising providing a pressure regulating valve. A high-pressure air ejection device in the acoustic test equipment according to claim 1, which is provided at a tip of a branch passage in the reverberation chamber to which compressed air is supplied, and immediately before the compressed air is ejected into the reverberation chamber. A jet nozzle configured to be narrowed down. 3. The jet nozzle according to claim 2, wherein the jet nozzle is bent into a crank shape in two steps. 3. The jet nozzle according to claim 2, wherein the jet nozzle is bent into an L-shape, and a spoiler is provided inside the vicinity of a tip end opening. The jet nozzle according to claim 2, wherein a tapered nozzle body is disposed on one side, and a blocking plate is disposed on the other side so as to obstruct the jet flow to be jetted. Jet nozzle. 3. A jet nozzle according to claim 2, wherein the jet nozzles are provided with tapered nozzle bodies facing each other so as to collide with a jet stream to be jetted. 7. The jet nozzle according to claim 5, wherein the tapered nozzle body is prepared in various sizes so that the diameter of the nozzle body can be changed and the interval between the nozzle body and the opposed nozzle body can be changed. Jet nozzle. 4. The jet nozzle according to claim 3, wherein a cross-sectional area of the nozzle outlet can be changed by a shutter provided near the nozzle outlet and operated by an actuator. 5. The jet nozzle according to claim 4, wherein a cross-sectional area of the nozzle outlet can be changed by a shutter provided back to back with the spoiler and operated by an actuator. 7. The jet nozzle according to claim 5, wherein a cross-sectional area of an outlet of the nozzle body is changeable by a shutter provided near the nozzle body outlet and operated by an actuator. 7. The jet nozzle according to claim 5, wherein the tapered nozzle main body is slidable, and the tapered nozzle main body is moved forward / backward by an actuator so that the interval between the tapered nozzle main body and the opposing nozzle main body can be changed. The jet nozzle characterized by the above. The jet nozzle according to claim 11, wherein a cross-sectional area of a tapered outlet of a pipe slidably connected to a tip end portion of the nozzle body is changeable by a shutter operated by an actuator.

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