Acoustic measuring system

Abstract

An acoustic measuring system for investigating a jet engine exhaust nozzle, comprising: a chamber comprising a composite wall; an inlet channel connected to the jet engine exhaust nozzle, the inlet channel disposed through the composite wall and configured to introduce a fluid through the jet engine exhaust nozzle into the interior space of the chamber; an outlet channel disposed through the composite wall and opposite the inlet channel, the outlet channel configured to conduct the fluid to leave the interior space of the chamber; a positioning mechanism disposed within the interior space of the chamber; and a data acquisition unit comprising an acoustic receiver and a recorder communicatively connected to the acoustic receiver.

Description

ACOUSTIC MEASURING SYSTEMTECHNICAE FIEED

[0001] The present disclosure generally relates to systems utilized for carrying out acoustic experimental investigations of various objects, and more particularly to systems utilized for measuring acoustic characteristics of various jet engine components such as exhaust nozzles.BACKGROUND

[0002] Physiological and psychological disease may be a result of acoustically polluted environment. Various objects, from household appliances to jet engine components, may contribute to environmental pollution by producing vibrations and acoustic noises. Manufacturers attempt to reduce acoustic pollution by modifying designs and improving manufacturing quality based on the experimental data obtained from acoustic investigations.

[0003] Acoustic examinations may be conducted using an array of acoustic transducers positioned at a distance of an object (i.e., acoustic source) to acquire the desired data. During said examinations, the transducers array may be shifted and repositioned in space to investigate different locations around the object, aiming for results with minimum error. Moving the array of transducers may be done manually which is time-consuming and prone to inaccuracy. Additionally, using an array of acoustic transducers may intensify interaction effects and alter the acoustic pressure field. Therefore, there is need for acoustic measuring systems comprising a single transducer in combination with a precise mechanism for positioning the transducer.SUMMARY

[0004] This summary is intended to provide an overview of the subject matter of one or more exemplary embodiments, and is not intended to identify essential elements or keyelements of the subject matter, nor is it intended to be used to determine the scope of the claimed implementations. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later. The proper scope of one or more exemplary embodiments may be ascertained from the claims set forth below in view of the detailed description below and the drawings.

[0005] In one general aspect, the present disclosure may describe an exemplary acoustic measuring system for investigating an exemplary jet engine exhaust nozzle. In an exemplary embodiment, an exemplary acoustic measuring system may comprise an exemplary chamber comprising an exemplary composite wall. In an exemplary embodiment, an exemplary composite wall may comprise an exemplary inner wall surrounding an exemplary interior space of an exemplary chamber. In an exemplary embodiment, an exemplary inner wall may comprise a plurality of exemplary acoustic polyurethane panels covering an exemplary interior side of an exemplary inner wall. In an exemplary embodiment, an exemplary composite wall may further comprise an exemplary external wall surrounding an exemplary inner wall. In an exemplary embodiment, an exemplary external wall may comprise a plurality of exemplary wooden panels configured to allow acoustic energy that is not absorbed by an exemplary inner wall to penetrate an exemplary external wall and leave an exemplary chamber.

[0006] In an exemplary embodiment, an exemplary acoustic measuring system may further comprise an exemplary inlet channel connected to an exemplary jet engine exhaust nozzle. In an exemplary embodiment, an exemplary inlet channel may be disposed through an exemplary composite wall and may be configured to introduce an exemplary fluid through an exemplary jet engine exhaust nozzle into an exemplary interior space of an exemplary chamber.

[0007] In an exemplary embodiment, an exemplary acoustic measuring system may further comprise an exemplary outlet channel disposed through an exemplary composite walland opposite an exemplary inlet channel. In an exemplary embodiment, an exemplary outlet channel may be configured to conduct an exemplary fluid to leave an exemplary interior space of an exemplary chamber.

[0008] In an exemplary embodiment, an exemplary acoustic measuring system may further comprise an exemplary positioning mechanism disposed within an exemplary interior space of an exemplary chamber. In an exemplary embodiment, an exemplary positioning mechanism may comprise an exemplary first mechanism. In an exemplary embodiment, an exemplary first mechanism may comprise an exemplary Z-linear motion mechanism having an exemplary end-effector. In an exemplary embodiment an exemplary Z-linear motion mechanism may be configured to move an exemplary end-effector along a height of an exemplary chamber. In an exemplary embodiment, an exemplary first mechanism may comprise an exemplary X-linear motion mechanism connected to an exemplary Z-linear motion mechanism. In an exemplary embodiment, an exemplary X-linear motion mechanism may be configured to move an exemplary Z-linear motion mechanism along a width of an exemplary chamber. In an exemplary embodiment, an exemplary first mechanism may comprise an exemplary Y-linear motion mechanism connected to an exemplary X-linear motion mechanism and may be configured to simultaneously move an exemplary X-linear and Z-linear motion mechanisms along a length of an exemplary chamber.

[0009] In an exemplary embodiment, an exemplary positioning mechanism may further comprise an exemplary second mechanism comprising an exemplary arm connected to an exemplary end-effector via an exemplary rotatable joint. In an exemplary embodiment, an exemplary rotatable joint may be configured to relatively rotate an exemplary arm with respect to an exemplary first mechanism and an exemplary jet engine exhaust nozzle.

[0010] In an exemplary embodiment, an exemplary acoustic measuring system may further comprise an exemplary data acquisition unit comprising an exemplary acoustic receiver connected to an exemplary arm and being capable of acquiring various acoustic characteristics of an exemplary jet engine exhaust nozzle. In an exemplary embodiment, an exemplary data acquisition unit may further comprise an exemplary recorder communicatively connected to an exemplary acoustic receiver and may be configured to save and export a plurality of exemplary data received from an exemplary acoustic receiver.

[0011] This Summary may introduce a number of concepts in a simplified format; the concepts are further disclosed within the “Detailed Description” section. This Summary is not intended to configure essential / key features of the claimed subject matter, nor is intended to limit the scope of the claimed subject matter.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The novel features which are believed to be characteristic of the present disclosure, as to its structure, organization, use and method of operation, together with further objectives and advantages thereof, will be better understood from the following drawings in which a presently preferred embodiment of the present disclosure will now be illustrated by way of example. It is expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the present disclosure. Embodiments of the present disclosure will now be described by way of example in association with the accompanying drawings in which:

[0013] FIG. 1A illustrates a perspective view of an acoustic measuring system, consistent with one or more embodiments of the present disclosure;

[0014] FIG. IB illustrates a schematic view of a second mechanism of a positioning mechanism, consistent with one or more embodiments of the present disclosure;

[0015] FIG. 2 illustrates a schematic view of a composite wall, consistent with one or more embodiments of the present disclosure;

[0016] FIG. 3 illustrates a schematic view of measurement points, consistent with one or more embodiments of the present disclosure;

[0017] FIG. 4 illustrates a box diagram of an acoustic measuring system, consistent with one or more embodiments of the present disclosure; and

[0018] FIG. 5 illustrates a flowchart of an acoustic measuring process, consistent with one or more embodiments of the present disclosure.DETAILED DESCRIPTION

[0019] In the following detailed description, numerous specific details are set forth by way of examples to provide a thorough understanding of the relevant teachings related to the exemplary embodiments. However, it should be apparent that the present teachings may be practiced without such details. In other instances, well known methods, procedures, components, and / or circuitry have been described at a relatively high-level, without detail, in order to avoid unnecessarily obscuring aspects of the present teachings.

[0020] The following detailed description is presented to enable a person skilled in the art to make and use the methods and devices disclosed in one or more exemplary embodiments of the present disclosure. For purposes of explanation, specific nomenclature is set forth to provide a thorough understanding of the present disclosure. However, it will be apparent to one skilled in the art that these specific details are not required to practice the disclosed exemplary embodiments. Descriptions of specific exemplary embodiments are provided only as representative examples. Various modifications to the exemplary implementations will be plain to one skilled in the art, and the general principles defined herein may be applied to other implementations and applications without departing from the scope of the present disclosure.The present disclosure is not intended to be limited to the implementations shown, but is to be accorded the widest possible scope consistent with the principles and features disclosed herein.

[0021] Disclosed herein is an exemplary acoustic measuring system for investigating acoustic characteristics of various exemplary objects comprising from household appliances to jet engine components such as exhaust nozzles. In an exemplary embodiment, exemplary objects may be in their real size and dimension or being scaled for laboratory experimentations.

[0022] FIG. 1A illustrates a perspective view of an acoustic measuring system 100, consistent with one or more embodiments of the present disclosure. In an exemplary embodiment, acoustic measuring system 100 may be utilized for investigating object 120. In an exemplary embodiment, acoustic measuring system 100 may comprise chamber 102. in an exemplary embodiment, chamber 102 may comprise height 104, width 106, length 108, and composite wall 112 that surrounds interior space 110 of chamber 102. In an exemplary embodiment, composite wall 112 may comprise a plurality of exemplary acoustic panels such as perforated metal panels 114 to absorb an exemplary acoustic energy emitted inside interior space 110 of chamber 102.

[0023] In an exemplary embodiment, acoustic measuring system 100 may further comprise inlet channel 116, and outlet channel 118. In an exemplary embodiment, acoustic measuring system may further comprise an exemplary positioning mechanism, and an exemplary data acquisition unit. In an exemplary embodiment, an exemplary positioning mechanism may be disposed within interior space 110 of chamber 102. In an exemplary embodiment, interior space 110 of chamber 102 may refer to an exemplary space encompassed by composite wall 112.

[0024] In an exemplary embodiment, an exemplary positioning mechanism may comprise any mechanism utilized for conducting and holding an exemplary acoustic receiverto a desired and determined position in interior space 110 of chamber 102. In an exemplary embodiment, an exemplary positioning mechanism may comprise an exemplary robotic arm configured to move in different directions, or any mechanism configured to transform an exemplary rotational motion of an exemplary motor or actuator to linear motions along at least three exemplary independent axes that are mutually orthogonal, for the purpose of positioning.

[0025] In an exemplary embodiment, with further reference to FIG. 1A, an exemplary positioning mechanism may comprise first mechanism 122 and second mechanism 130. In an exemplary embodiment, first mechanism 122 may comprise end-effector 125, and at least three exemplary linear motion mechanisms connected to each other. In an exemplary embodiment, “linear motion mechanism” may refer to any mechanism that generates linear or translational motion along an exemplary predefined linear direction or axis. In an exemplary embodiment, at least three exemplary linear motion mechanisms may be mutually orthogonal such that each one of the at least three exemplary linear motion mechanisms may move end-effector 125 along height 104, width 106, and length 108 of chamber 102, respectively.

[0026] In an exemplary embodiment, first mechanism 122 of an exemplary positioning mechanism may comprise Z-linear motion mechanism 124. In an exemplary embodiment, Z- linear motion mechanism may comprise end-effector 125. In an exemplary embodiment, Z- linear motion mechanism 124 may be configured to move end-effector 125 along height 104 of chamber 102. In an exemplary embodiment, Z-linear motion mechanism 124 may comprise any mechanism that generates linear or translational motion along height 104 of chamber 102. In an exemplary embodiment, Z-linear motion mechanism 124 may comprise an exemplary ball screw or leadscrew mechanism that converts rotary motion of an exemplary drive motor to linear motion of an exemplary nut through engaging exemplary nut with exemplary screw shaft.

[0027] In an exemplary embodiment, with further reference to FIG. 1A, first mechanism 122 of an exemplary positioning mechanism may further comprise X-linear motion mechanism 126 connected to Z-linear motion mechanism 124. In an exemplary embodiment, X-linear motion mechanism 126 configured to move Z-linear motion mechanism 124 along width 106 of chamber 102. In an exemplary embodiment, X-linear motion mechanism 126 may comprise any mechanism that generates linear or translational motion along width 106 of chamber 102. In an exemplary embodiment, X-linear motion mechanism 126 may comprise an exemplary ball screw or leadscrew mechanism that converts rotary motion of an exemplary drive motor to linear motion of an exemplary nut through engaging exemplary nut with exemplary screw shaft. In an exemplary embodiment, an exemplary nut of X-linear motion mechanism 126 may be connected to Z-linear motion mechanism 124 such that X-linear motion mechanism 126 may be capable of moving Z-linear motion mechanism 124 and end-effector 125 along width 106 of chamber 102.

[0028] In an exemplary embodiment, with further reference to FIG. 1A, first mechanism 122 of an exemplary positioning mechanism may further comprise Y -linear motion mechanism 128 connected to X-linear motion mechanism 126. In an exemplary embodiment, Y-linear motion mechanism 128 may be configured to move X-linear motion mechanism 126 along length 108 of chamber 102. As a result, Z-linear motion mechanism 124 may be simultaneously moved along length 108 of chamber 102. In an exemplary embodiment, Y-linear motion mechanism 128 may comprise any mechanism that generates linear or translational motion along length 108 of chamber 102. In an exemplary embodiment, Y-linear motion mechanism 128 may comprise an exemplary ball screw or leadscrew mechanism that converts rotary motion of an exemplary drive motor to linear motion of an exemplary nut through engaging exemplary nut with exemplary screw shaft. In an exemplary embodiment, an exemplary nut ofY-linear motion mechanism 128 may be connected to X-linear motion mechanism 126 such that Y-linear motion mechanism 128 may be capable of simultaneously moving X-linear and Z-linear motion mechanisms 126,124 and end-effector 125 along length 108 of chamber 102. In an exemplary embodiment, an exemplary positioning mechanism may further comprise second mechanism 130 on which an exemplary acoustic receiver may be mounted.

[0029] In an exemplary embodiment, an exemplary data acquisition unit may comprise an exemplary acoustic receiver such as an exemplary microphone connected to second mechanism 130. In an exemplary embodiment, an exemplary acoustic receiver may be capable of acquiring various acoustic characteristics of object 120. In an exemplary embodiment, an exemplary data acquisition unit may further comprise an exemplary recorder. In an exemplary embodiment, an exemplary recorder may be communicatively connected to an exemplary acoustic receiver and may be configured to save and export a plurality of data received from an exemplary acoustic receiver.

[0030] In an exemplary embodiment, an exemplary fluid flow is needed for obtaining acoustic features of an exemplary object. In such circumstances, an exemplary acoustic measuring system may further comprise an exemplary fluid inlet and outlet to direct an exemplary fluid to flow through or around an exemplary object. In an exemplary embodiment, an exemplary compressor may be connected to an exemplary fluid inlet to supply pressurized fluid needed during an examination process. In an exemplary embodiment, with further reference to FIG. 1A, acoustic measuring system 100 may further comprise inlet channel 116 and outlet channel 118. In an exemplary embodiment, inlet channel 116 may be connected to object 120 whose acoustic characteristics are under investigation. In an exemplary embodiment, object 120 may comprise an exemplary jet engine component such as anexemplary exhaust nozzle. In an exemplary embodiment, an exemplary exhaust nozzle may be a chevron nozzle.

[0031] In an exemplary embodiment, inlet channel 116 may be disposed through composite wall 112. In an exemplary embodiment, inlet channel 116 may be configured to introduce an exemplary fluid through an exemplary jet engine exhaust nozzle and conduct an exemplary fluid into interior space 110 of chamber 102. In an exemplary embodiment, outlet channel 118 may be disposed through composite wall 112, opposite inlet channel 116. In an exemplary embodiment, outlet channel 118 may be configured to conduct an exemplary fluid to leave interior space 110 of chamber 102. In an exemplary embodiment, outlet channel 118 may comprise an exemplary funnel-shaped entrance, placed within chamber 102. In an exemplary embodiment, an exemplary funnel-shaped entrance may be connected to an exemplary cylindrical channel to direct an exemplary fluid to leave interior space 110 of chamber 102.

[0032] FIG. IB illustrates a schematic view 101 of a second mechanism 130 of a positioning mechanism, consistent with one or more embodiments of the present disclosure. In an exemplary embodiment, an exemplary positioning mechanism may further comprise second mechanism 130 connected to Z-linear motion mechanism 124 of first mechanism 122. In an exemplary embodiment, second mechanism 130 may comprise arm 132 which is connected to end-effector 125 via rotatable joint 134. In an exemplary embodiment, an exemplary acoustic receiver such as microphone 136 may be connected to arm 132. In an exemplary embodiment, rotatable joint 134 may be configured to relatively rotate arm 132 with respect to first mechanism 122 and jet engine exhaust nozzle 120 such that microphone 136 may be located in desired exemplary measuring points. In an exemplary embodiment, rotatable joint 134 may comprise first joint 134a having at least a single rotational degree of freedom about anexemplary Z-axis which is parallel to height 104 of chamber 102 so that first joint 134a may rotate arm 132 about an exemplary Z-axis. In an exemplary embodiment, rotatable joint 134 may further comprise a second joint 134b having at least a single rotational degree of freedom about an exemplary arbitrary axis which is perpendicular to an exemplary Z-axis.

[0033] FIG. 2 illustrates a schematic view 200 of a composite wall 212, consistent with one or more embodiments of the present disclosure. In an exemplary embodiment, an exemplary chamber of an exemplary acoustic measuring system may comprise an exemplary composite wall to construct an exemplary isolated environment inside an exemplary chamber such that an interior space of an exemplary chamber may resemble a free field.

[0034] In an exemplary embodiment, with further reference to FIGs. 1A-2, composite wall 212 may comprise inner wall 202 and external wall 204. In an exemplary embodiment, inner wall 202 may surround interior space 110 of chamber 102. In an exemplary embodiment inner wall 202 may comprise a plurality of acoustic panels (e.g., acoustic panel 206) that covers interior side 210 of inner wall 202. In an exemplary embodiment, interior side 210 of inner wall 202 may refer to an exemplary side of inner wall 202 which faces toward interior space 110 of chamber 102. In an exemplary embodiment, acoustic panels may absorb almost all acoustic energy in an exemplary operating frequency range to construct an exemplary free field. In an exemplary embodiment, at least one acoustic panel 206 may comprise an exemplary egg-crate- shaped panel, in an exemplary embodiment, at least one acoustic panel 206 may be made of porous or spongy materials. In an exemplary embodiment, at least one acoustic panel 206 may comprise polyurethane open cell panel.

[0035] In an exemplary embodiment, with further reference to FIGs. 1A-2, external wall 204 may be adjacent to inner wall 202 and may surround inner wall 202. In an exemplary embodiment, an acoustic energy produced by object 120 may not be thoroughly absorbed byinner wall 202. As a result, some of the acoustic energy may pass through inner wall 202, while some of that may reflect backward and propagate in interior space 110 of chamber 102. In an exemplary embodiment, various materials may be used as an exemplary liner to cover interior side 210 of inner wall 202, in order to absorb or transmit maximum amount of acoustic energy and prevent reflections. In an exemplary embodiment, exemplary perforated panels or tiles (e.g., perforated metal panel 114 depicted in FIG. 1A) may partially cover inner side 210 of inner wall 202. In an exemplary embodiment, an exemplary frequency above which acoustic energy is absorbed by exemplary perforated panels or tiles may be determined by the size and density of exemplary perforations.

[0036] In an exemplary embodiment, acoustic penetrability may be dependent on frequency. In an exemplary embodiment, inner wall 202 may absorb an acoustic energy above an exemplary frequency and transmit energy below the exemplary frequency. In an exemplary embodiment, external wall 204 may comprise a plurality of panels configured to allow acoustic energy that is not absorbed by inner wall 202 to penetrate external wall 204 and leave chamber 102. In an exemplary embodiment, external wall 204 may comprise a plurality of wooden panels (e.g., wooden panel 208).

[0037] FIG. 3 illustrates a schematic view 300 of measurement points, consistent with one or more embodiments of the present disclosure. In an exemplary embodiment, for measuring acoustic features of an exemplary object an exemplary set of points needed to be determined at which acoustic measurements may be performed. In an exemplary embodiment, exemplary loci of exemplary measurement points may lie on an outer surface of an exemplary sphere whose center coincides with a center of an exemplary object under investigation.

[0038] In an exemplary embodiment, an exemplary acoustic receiver, such as microphone 302, may be moved on outer surface of several spheres (e.g., sphere 310a, 310b)and halted at regular intervals to obtain data about different acoustic features of exhaust nozzle 312. In an exemplary embodiment, an exemplary positioning mechanism may be capable of moving microphone 302 on an exemplary imaginary sphere. In an exemplary embodiment, an exemplary imaginary sphere may have an exemplary center that coincides an exemplary center of jet engine exhaust nozzle 312 and may have an exemplary diameter in a range of about 40 to 50 times an exemplary diameter of jet engine exhaust nozzle 312.

[0039] In an exemplary embodiment, a set of exemplary measurement points (e.g., measurement point 304) may comprise a plurality of exemplary measurement points which are located on outer surface of spheres 310a-310b whose center 306 coincide with an exemplary center of exhaust nozzle 306. In an exemplary embodiment, angle 308 may be defined between an exemplary radius of sphere 310a or 310b passing measurement point 304, and exhaust nozzle’s central axis 314. In an exemplary embodiment, angle 308 may be between about O’ and 180° and microphone 302 may be dwelled on outer surface of sphere 310a or 310b at regular intervals of l 0°to acquire data. In an exemplary embodiment, angle 308 may be between about 3CT and 120° and microphone 302 may be dwelled on outer surface of sphere 310a or 310b at regular intervals of 10° to acquire data. In an exemplary embodiment, the diameter of sphere 310a and 310b may be respectively 40 times and 50 times the diameter of exhaust nozzle 312 to allow microphone 302 measures acoustic parameters in an exemplary far field.

[0040] FIG. 4 illustrates a box diagram 400 of an acoustic measuring system, consistent with one or more embodiments of the present disclosure. In an exemplary embodiment, an exemplary acoustic measuring system may be utilized to acquire acoustic features of an exemplary jet engine exhaust nozzle, chevron nozzle 406 disposed within an exemplary anechoic or acoustic chamber (e.g., chamber 402). In an exemplary embodiment, for the purpose of investigating acoustic characteristics of chevron nozzle 406, an exemplary acousticmeasuring system may comprise compressor unit 404 to supply an exemplary pressurized fluid which flows through chevron nozzle 406 and produces acoustic waves 416. In an exemplary embodiment, compressor unit 404 may be communicatively connected to control & processing unit (CPU) 424. In an exemplary embodiment, an exemplary user may apply commands 426 in associated with fluid flow parameters such as flow pressure, temperature, velocity, etc., to compressor unit 404 through CPU 424.

[0041] In an exemplary embodiment, with reference to FIG. 4, an exemplary acoustic measuring system may further comprise positioning mechanism 408 and data acquisition 418 which are communicatively connected to control & processing unit (CPU) 424. In an exemplary embodiment, data acquisition unit 418 may comprise acoustic receiver 420, such as an exemplary microphone, which may be capable of receiving and transmitting acoustic waves 416 to recorder 422. In an exemplary embodiment, recorder 422 may be capable of saving, analyzing and exporting various data received from acoustic receiver 420. In an exemplary embodiment, recorder 422 may comprise any recorder at least capable of recording sounds with sample rate and bit depth higher than 96kHz / 24-bit. In an exemplary embodiment, exemplary outputs of data acquisition unit 418 may be transmitted to CPU 424 for further process.

[0042] In an exemplary embodiment, with further reference to FIG. 4, acoustic receiver 420 may be positioned inside chamber 402 via positioning mechanism 408. In an exemplary embodiment, positioning mechanism 408 may comprise first mechanism 412 and second mechanism 414. In an exemplary embodiment, first mechanism 412 may comprise an exemplary end-effector and at least three exemplary linear motion mechanisms. In an exemplary embodiment, at least three exemplary linear motion mechanisms may be connected to each other and being mutually orthogonal such that each one of the at least three exemplary linear motion mechanisms moves an exemplary end-effector along a width, length, and heightof chamber 402, respectively. In an exemplary embodiment, at least three exemplary linear motion mechanisms may receive user commands 426 applied to CPU 424 based on starting or pausing motion along three orthogonal directions (e.g., a width, length, and height of chamber 402), through driver unit 410. In an exemplary embodiment, each exemplary linear motion mechanism may comprise any mechanism which is capable of producing linear motion such as leadscrew or ball-screw mechanism. In an exemplary embodiment, driver unit 410 may be connected to an exemplary power generating component (e.g., electric motor) of a corresponding exemplary linear motion mechanism to control the motion thereof.

[0043] In an exemplary embodiment, acoustic receiver 420 may be connected to first mechanism 412 of positioning mechanism 402 via second mechanism 414. In an exemplary embodiment, second mechanism 414 may be capable of rotating acoustic receiver 420 inside chamber 402 in order to position acoustic receiver 420 in an exemplary far field with respect to chevron nozzle 406. In an exemplary embodiment, an exemplary user may determine exemplary measurement points and transmit corresponding orders to positioning mechanism 408 through CPU 424 for locating acoustic receiver 420 at said exemplary measurement points.

[0044] FIG. 5 illustrates a flowchart of an acoustic measuring process 500, consistent with one or more embodiments of the present disclosure. In an exemplary embodiment, acoustic measuring process 500 may comprise: determining measurement points (step 502); performing acoustic measurements at measurement points (step 504); and analyzing acoustic measurements (step 506).

[0045] In further detail with respect to step 502, step 502 may include determining an exemplary set of measurement points to position an exemplary acoustic receiver at said measurement points and obtain data about acoustic parameters of an exemplary object under observation. In an exemplary embodiment, in order to acquire precise and reliable data aboutacoustic features of an exemplary object, an exemplary measurement points may be located at a distance of the exemplary object so that far field noises may be measured. In an exemplary embodiment, “far field” may refer to an exemplary region where pressure and velocity of sound align and are in phase. In an exemplary embodiment, considering an exemplary jet engine exhaust nozzle as an exemplary object under investigation, exemplary measurement points may lie on an outer surface of an exemplary sphere whose center may coincide with the center of an exemplary exhaust nozzle exit, and the diameter may be greater than 40 times the exemplary exhaust nozzle diameter. In an exemplary embodiment, exemplary measurement points may be distributed on outer surface of an exemplary sector of an exemplary sphere. In an exemplary embodiment, an exemplary angle between exemplary radii defining an exemplary sector of an exemplary sphere may be in the range about (T to 180°.

[0046] In further detail with respect to step 504, step 504 may include performing exemplary acoustic measurements at exemplary measurement points. In an exemplary embodiment, exemplary acoustic measurements may include a plurality of data about sound directivity, sound pressure levels, etc. In an exemplary embodiment, an exemplary positioning mechanism may be used to move an exemplary acoustic receiver (e.g., a microphone) among exemplary measurement points. In an exemplary embodiment, an exemplary acoustic receiver (e.g., a microphone) may dwell at a single measurement point during an experiment to obtain desired data about said measurement point, and then move to next measurement point, repeating the process.

[0047] In further detail with respect to step 506, step 506 may include analyzing acoustic measurements which is performed by an exemplary data acquisition unit. In an exemplary embodiment, an exemplary data acquisition unit may comprise an exemplary recorder capable of saving, analyzing and exporting various data received from an exemplary acoustic receiver(e.g., a microphone). In an exemplary embodiment, an exemplary recorder may comprise any recorder at least capable of recording sounds with sample rate and bit depth higher than 96kHz / 24-bit.

[0048] While the foregoing has described what are considered to be the best mode and / or other examples, it is understood that various modifications may be made therein and that the subject matter disclosed herein may be implemented in various forms and examples, and that the teachings may be applied in numerous applications, only some of which have been described herein. It is intended by the following claims to claim any and all applications, modifications and variations that fall within the true scope of the present teachings.

[0049] Unless otherwise stated, all measurements, values, ratings, positions, magnitudes, sizes, and other specifications that are set forth in this specification, including in the claims that follow, are approximate, not exact. They are intended to have a reasonable range that is consistent with the functions to which they relate and with what is customary in the art to which they pertain.

[0050] The scope of protection is limited solely by the claims that now follow. That scope is intended and should be interpreted to be as broad as is consistent with the ordinary meaning of the language that is used in the claims when interpreted in light of this specification and the prosecution history that follows and to encompass all structural and functional equivalents. Notwithstanding, none of the claims are intended to embrace subject matter that fails to satisfy the requirement of Sections 101, 102, or 103 of the Patent Act, nor should they be interpreted in such a way. Any unintended embracement of such subject matter is hereby disclaimed.

[0051] Except as stated immediately above, nothing that has been stated or illustrated is intended or should be interpreted to cause a dedication of any component, step, feature, object,benefit, advantage, or equivalent to the public, regardless of whether it is or is not recited in the claims.

[0052] It will be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein. Relational terms such as first and second and the like may be used solely to distinguish one entity or action from another without necessarily requiring or implying any actual such relationship or order between such entities or actions. An element proceeded by “a” or “an” does not, without further constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0053] It will be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study, except where specific meanings have otherwise been set forth herein. Relational terms such as “first” and “second” and the like may be used solely to distinguish one entity or action from another without necessarily requiring or implying any actual such relationship or order between such entities or actions.

[0054] The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it may be seen that various features are grouped together in various implementations. This is for purposes of streamlining the disclosure, and is not to be interpreted as reflecting an intention that the claimed implementations require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed implementation. Thus, the following claimsare hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter.

[0055] While various implementations have been described, the description is intended to be exemplary, rather than limiting and it will be apparent to those of ordinary skill in the art that many more implementations and implementations are possible that are within the scope of the implementations. Although many possible combinations of features are shown in the accompanying figures and discussed in this detailed description, many other combinations of the disclosed features are possible. Any feature of any implementation may be used in combination with or substituted for any other feature or element in any other implementation unless specifically restricted. Therefore, it will be understood that any of the features shown and / or discussed in the present disclosure may be implemented together in any suitable combination. Accordingly, the implementations are not to be restricted except in light of the attached claims and their equivalents. Also, various modifications and changes may be made within the scope of the attached claims.

Claims

What is claimed is:

1. An acoustic measuring system for investigating a jet engine exhaust nozzle, the acoustic measuring system comprising: a chamber comprising: a composite wall comprising: an inner wall surrounding an interior space of the chamber, the inner wall comprising a plurality of acoustic polyurethane panels covering an interior side of the inner wall; and an external wall surrounding the inner wall, the external wall comprising a plurality of wooden panels configured to allow acoustic energy that is not absorbed by the inner wall to penetrate the external wall and leave the chamber; an inlet channel connected to the jet engine exhaust nozzle, the inlet channel disposed through the composite wall and configured to introduce a fluid through the jet engine exhaust nozzle into the interior space of the chamber; an outlet channel disposed through the composite wall and opposite the inlet channel, the outlet channel configured to conduct the fluid to leave the interior space of the chamber; a positioning mechanism disposed within the interior space of the chamber, the positioning mechanism comprising: a first mechanism comprising: a Z-linear motion mechanism having an end-effector, the Z-linear motion mechanism configured to move the end-effector along a height of the chamber; an X-linear motion mechanism connected to the Z-linear motion mechanism, the X-linear motion mechanism configured to move the Z-linear motion mechanism along a width of the chamber; anda Y-linear motion mechanism connected to the X-linear motion mechanism and configured to simultaneously move the X-linear and Z-linear motion mechanisms along a length of the chamber; and a second mechanism comprising an arm connected to the end-effector via a rotatable joint, the rotatable joint configured to relatively rotate the arm with respect to the first mechanism and the jet engine exhaust nozzle; and a data acquisition unit comprising: an acoustic receiver connected to the arm and being capable of acquiring various acoustic characteristics of the jet engine exhaust nozzle; and a recorder communicatively connected to the acoustic receiver and configured to save and export a plurality of data received from the acoustic receiver.

2. An acoustic measuring system for investigating an object, the acoustic measuring system comprising: a chamber comprising: a composite wall comprising: an inner wall surrounding an interior space of the chamber; and an external wall surrounding the inner wall, the external wall configured to allow acoustic energy that is not absorbed by the inner wall to penetrate the external wall and leave the chamber; a positioning mechanism disposed within the interior space of the chamber, the positioning mechanism comprising: a first mechanism comprising: an end-effector; andat least three linear motion mechanisms connected to each other and being mutually orthogonal such that each one of the at least three linear motion mechanisms moves the end-effector along a width, length, and height of the chamber, respectively; and a second mechanism comprising an arm connected to the first mechanism via a rotatable joint, the rotatable joint configured to rotate the arm with respect to the first mechanism and the object; and a data acquisition unit comprising: an acoustic receiver connected to the arm and being capable of acquiring various acoustic characteristics of the object; and a recorder communicatively connected to the acoustic receiver and configured to save and export a plurality of data received from the acoustic receiver.

3. The acoustic measuring system of claim 2, wherein the inner wall comprises a plurality of acoustic polyurethane panels covering an interior side of the inner wall.

4. The acoustic measuring system of claim 3, wherein the plurality of acoustic polyurethane panels are egg-crate- shaped panels.

5. The acoustic measuring system of claim 2, wherein the external wall comprising a plurality of wooden panels.

6. The acoustic measuring system of claim 2 further comprising an inlet channel connected to the object, the inlet channel disposed through the composite wall and configured to introduce a fluid through the object into the interior space of the chamber.

7. The acoustic measuring system of claim 6 further comprising an outlet channel disposed through the composite wall and opposite the inlet channel, the outlet channel configured to conduct the fluid to leave the interior space of the chamber.

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