CN114211826A - Double-freedom-degree acoustic liner in engine case and design and processing method thereof - Google Patents

Double-freedom-degree acoustic liner in engine case and design and processing method thereof Download PDF

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CN114211826A
CN114211826A CN202111442928.1A CN202111442928A CN114211826A CN 114211826 A CN114211826 A CN 114211826A CN 202111442928 A CN202111442928 A CN 202111442928A CN 114211826 A CN114211826 A CN 114211826A
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sound
absorbing plate
freedom
degree
perforated
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CN114211826B (en
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侯鹏
商旭静
郑文涛
董阳
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AECC Shenyang Engine Research Institute
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/02—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by structural features of a fibrous or filamentary layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
    • B32B3/10—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a discontinuous layer, i.e. formed of separate pieces of material
    • B32B3/12—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a discontinuous layer, i.e. formed of separate pieces of material characterised by a layer of regularly- arranged cells, e.g. a honeycomb structure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
    • B32B37/06—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the heating method
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
    • B32B37/10—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the pressing technique, e.g. using action of vacuum or fluid pressure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
    • B32B37/12—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by using adhesives
    • B32B37/1284—Application of adhesive
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/08—Interconnection of layers by mechanical means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
    • F02C7/00—Features, components parts, details or accessories, not provided for in, or of interest apart form groups F02C1/00 - F02C6/00; Air intakes for jet-propulsion plants
    • F02C7/24—Heat or noise insulation
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
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    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/10—Properties of the layers or laminate having particular acoustical properties
    • B32B2307/102—Insulating
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/10—Noise analysis or noise optimisation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation

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Abstract

The application relates to a method for designing a double-freedom-degree sound liner in an engine casing, which comprises the following steps: the method for checking the resonance frequency of the sound liner with two degrees of freedom specifically comprises the following steps:
Figure DDA0003383962950000011
Figure DDA0003383962950000012
at frLess than or equal to f of noise frequency of engine main bodyr1Checking the resonance frequency of the two-degree-of-freedom acoustic liner; wherein f isrChecking a lower limit for the resonance frequency of the acoustic liner with two degrees of freedom; f. ofr1Checking the upper limit of the resonance frequency of the acoustic liner with two degrees of freedom; c is the equivalent sound velocity of the noise static flow field of the engine main body; sigma 1 is the perforation rate of the sound absorption holes on the inner side perforated sound absorption plate; sigma 2 is the perforation rate of the sound absorption holes on the outer perforated sound absorption plate; k1 is the thickness of the inside honeycomb core; k2 is the thickness of the outside honeycomb core; t1 is the thickness of the inside perforated sound deadening plate; t2 is the thickness of the outer perforated sound deadening plate. In addition, the invention relates to a double-freedom-degree acoustic liner in an engine case, which is designed by the design method of the double-freedom-degree acoustic liner in the engine case, and relates to a machining method of the double-freedom-degree acoustic liner in the engine case, which is used for machining the double-freedom-degree acoustic liner in the engine case.

Description

Double-freedom-degree acoustic liner in engine case and design and processing method thereof
Technical Field
The application belongs to the technical field of double-freedom-degree sound linings in engine casings and design and processing of the double-freedom-degree sound linings, and particularly relates to a double-freedom-degree sound lining in an engine casing and a design and processing method of the double-freedom-degree sound lining.
Background
In order to reduce the influence of the noise of the aircraft engine, a double-freedom-degree sound liner is arranged in a casing and mainly comprises an inner side perforated sound-absorbing plate 1, an inner side honeycomb core 2, an outer side perforated sound-absorbing plate 3, an outer side honeycomb core 4 and a back plate 5 which are sequentially bonded, as shown in figure 1, for the convenience of assembly, the sound liner is mostly designed into a sectional type, and each section is assembled into the casing in a push-in or plug-in mode and is connected into the casing through a screw, as shown in figure 2.
The two-degree-of-freedom sound lining in the current engine case is made of composite materials, the strength of the designed inner and outer perforated sound-absorbing boards and the anti-stripping performance of the sound lining cannot be effectively guaranteed, the sound absorption performance of the two-degree-of-freedom sound lining cannot be effectively guaranteed, the two-degree-of-freedom sound lining obtained by scaling design is easy to deform along with the change of curvature, in addition, the two-degree-of-freedom sound lining is difficult to guarantee that the blocking rate of the sound hole in the outer perforated sound-absorbing board 3 is at a lower level during processing, when the blocked sound hole is processed, the sound lining structure is easy to be damaged, and the sound lining structure is easy to be misplaced during processing.
The present application has been made in view of the above-mentioned technical drawbacks.
It should be noted that the above background disclosure is only for the purpose of assisting understanding of the inventive concept and technical solutions of the present invention, and does not necessarily belong to the prior art of the present patent application, and the above background disclosure should not be used for evaluating the novelty and inventive step of the present application without explicit evidence to suggest that the above content is already disclosed at the filing date of the present application.
Disclosure of Invention
The present application is directed to a two degree of freedom acoustic liner in an engine case and a method of designing and machining the same to overcome or alleviate at least one of the known deficiencies.
The technical scheme of the application is as follows:
on the one hand, the design method of the double-freedom-degree sound liner in the engine casing comprises the following steps:
the resonance frequency of the acoustic liner with two degrees of freedom is checked, and the method specifically comprises the following steps:
Figure BDA0003383962930000021
Figure BDA0003383962930000022
at frLess than or equal to f of noise frequency of engine main bodyr1Checking the resonance frequency of the two-degree-of-freedom acoustic liner;
wherein the content of the first and second substances,
frchecking a lower limit for the resonance frequency of the acoustic liner with two degrees of freedom;
fr1for a double degree of freedom acoustic liner resonance frequencyRate checking the upper limit;
c is the equivalent sound velocity of the noise static flow field of the engine main body;
sigma 1 is the perforation rate of the sound absorption holes on the inner side perforated sound absorption plate;
sigma 2 is the perforation rate of the sound absorption holes on the outer perforated sound absorption plate;
k1 is the thickness of the inside honeycomb core;
k2 is the thickness of the outside honeycomb core;
t1 is the thickness of the inside perforated sound deadening plate;
t2 is the thickness of the outer perforated sound deadening plate.
According to at least one embodiment of the application, in the above two-degree-of-freedom acoustic liner design method in the engine case, when Ma is less than or equal to 0.2, C is equal to C0；
In Ma>0.2, forward flow noise C ═ 1+ Ma) C0The reverse flow noise C ═ 1-Ma) C0；
Wherein the content of the first and second substances,
C0the sound velocity of the noise static flow field of the engine body.
According to at least one embodiment of the present application, when the sound absorbing holes on the inner perforated sound absorbing plate and the outer sound absorbing plate are arranged in a triangle in the above-mentioned method for designing the two-degree-of-freedom acoustic liner in the engine casing:
σ1＝(0.95·d1/a1)2；
σ2＝(0.95·d2/a2)2；
when the sound absorbing holes on the inner side perforated sound absorbing plate and the outer side sound absorbing plate are arranged in a square shape:
Figure BDA0003383962930000031
Figure BDA0003383962930000032
wherein the content of the first and second substances,
d1 is the diameter of the sound absorbing hole on the sound absorbing plate with the inner side perforated;
a1 is the distance between sound absorbing holes on the sound absorbing plate with inner side holes;
d2 is the diameter of the sound absorbing hole on the sound absorbing plate with the perforated outer side;
a2 is the distance between sound holes on the outer perforated sound absorbing plate.
According to at least one embodiment of the present application, the above method for designing a two-degree-of-freedom acoustic liner in an engine casing further includes:
checking the prepreg fiber integrity of the inner side perforated sound-absorbing plate and the outer side perforated sound-absorbing plate specifically as follows:
when the sound absorption holes on the inner side perforated sound absorption plate and the outer side sound absorption plate are arranged in a triangular mode, the integrity rates of weft and warp fibers of the inner side perforated sound absorption plate and the outer side sound absorption plate are calculated according to the following formulas:
the prepreg fiber laying angle beta is 0 degree or +/-60 degrees:
weft integrity rate: (sin60 °. a-d)/(sin60 °. a);
warp integrity rate: (a-2 d)/a;
the prepreg fiber lay-up angles β are ± 30 ° and 90 °:
weft integrity rate: (a-2d)/a
Warp integrity rate: (sin60 °. a-d)/(sin60 °. a);
when the sound absorption holes on the inner side perforated sound absorption plate and the outer side sound absorption plate are arranged in a square shape, the integrity rates of weft and warp fibers of the inner side perforated sound absorption plate and the outer side sound absorption plate are calculated according to the following formulas:
the prepreg fiber lay-up angle β is 0 ° or 90 °:
weft integrity rate: (a-d)/a;
warp integrity rate: (a-d)/a;
the prepreg fiber lay-up angle beta is +/-45 degrees:
weft integrity rate: (a-2d sin45 °)/a;
warp integrity rate: (a-2d sin45 °)/a;
when the fiber integrity of the weft and warp of the inner side perforated sound-absorbing plate is greater than the fiber integrity threshold of the inner side perforated sound-absorbing plate, checking the fiber integrity of the weft and warp of the inner side perforated sound-absorbing plate;
when the fiber integrity of the weft and warp of the outer perforated sound-absorbing plate is greater than the fiber integrity threshold of the outer perforated sound-absorbing plate, the fiber integrity of the weft and warp of the inner perforated sound-absorbing plate is checked;
wherein the content of the first and second substances,
a is the distance between sound absorbing holes on the inner side perforated sound absorbing plate and the outer side perforated sound absorbing plate;
d is the diameter of the sound absorbing hole on the inner side perforated sound absorbing plate and the outer side perforated sound absorbing plate.
According to at least one embodiment of the application, in the method for designing the acoustic liner with two degrees of freedom in the engine case, the threshold value of the fiber integrity of the inner perforated sound absorption plate is 50%;
the fiber integrity threshold of the outer perforated acoustical panel is 40%.
According to at least one embodiment of the present application, the above method for designing a two-degree-of-freedom acoustic liner in an engine casing further includes:
when the two-degree-of-freedom acoustic liner is subjected to scaling design, the curvature of the two-degree-of-freedom acoustic liner after scaling is M times of the original curvature, the circumferential length of each section of the two-degree-of-freedom acoustic liner after scaling is not less than M times of the original length, and the number of sections is no more than the number of original sections/M.
On the other hand, the double-freedom-degree sound lining in the engine case is designed by any one of the above design methods for the double-freedom-degree sound lining in the engine case, wherein the inner perforated sound-absorbing plate, the inner honeycomb core, the outer perforated sound-absorbing plate, the outer honeycomb core and the back plate are bonded by glue films.
In another aspect, a method for processing a two-degree-of-freedom acoustic liner in an engine case is provided, which is used for processing the two-degree-of-freedom acoustic liner in the engine case, and includes:
bonding the outer honeycomb core, the outer perforated sound-absorbing plate and the outer honeycomb core by using adhesive films;
punching adhesive films among the lateral honeycomb core, the lateral perforated sound-absorbing plate and the lateral honeycomb core by using a high-pressure air source to ensure that the blocking rate of sound absorbing holes on the lateral perforated sound-absorbing plate is lower than the blocking rate threshold of the sound absorbing holes of the lateral perforated sound-absorbing plate;
bonding the inner perforated silencing plate and the inner honeycomb core by using an adhesive film;
punching a glue film between the inner side perforated sound-absorbing plate and the inner side honeycomb core to ensure that the blocking rate of sound absorbing holes on the inner side perforated sound-absorbing plate is lower than the blocking rate threshold value of the sound absorbing holes of the inner side perforated sound-absorbing plate;
bonding the outer honeycomb core and the back plate by using a glue film;
and placing the inner side perforated sound-absorbing plate, the inner side honeycomb core, the outer side perforated sound-absorbing plate, the outer side honeycomb core and the back plate in a female die and a male die for pressing, heating and pressurizing to melt and bond the inner side perforated sound-absorbing plate, the inner side honeycomb core, the outer side perforated sound-absorbing plate, the outer side honeycomb core and the glue film between the back plates.
According to at least one embodiment of the application, in the machining method for the acoustic liner with two degrees of freedom in the engine case, the blocking rate threshold value of the sound-absorbing hole of the inner perforated sound-absorbing plate is 2%;
the threshold value of the blockage rate of the silencing holes of the outer perforated silencing plate is 2%.
According to at least one embodiment of the application, in the above method for processing the two-degree-of-freedom acoustic liner in the engine casing, after the inner perforated sound-absorbing plate, the inner honeycomb core, the outer perforated sound-absorbing plate, the outer honeycomb core and the back plate are placed in the female die and the male die and pressed tightly, a plurality of positioning pins are connected to the female die or the male die, and each positioning pin correspondingly extends into one bolt hole in the two-degree-of-freedom acoustic liner.
Drawings
FIG. 1 is a schematic illustration of a two degree of freedom acoustic liner in an engine case according to an embodiment of the present disclosure;
FIG. 2 is a schematic illustration of a two degree of freedom acoustic liner assembled into an engine case provided by an embodiment of the present application;
FIG. 3 is a schematic diagram of an inner perforated sound absorbing plate and outer sound absorbing holes arranged in a triangle according to an embodiment of the present application;
FIG. 4 is a schematic diagram of an inner perforated sound absorbing panel and an outer sound absorbing panel with holes arranged in a square pattern according to an embodiment of the present application;
FIG. 5 is a schematic illustration of a scaled design of a two degree-of-freedom acoustic liner within an engine case as provided by an embodiment of the present application;
FIG. 6 is a schematic illustration of a two degree of freedom acoustic liner machining within an engine case provided by an embodiment of the present application;
wherein:
1-inner side perforated sound-absorbing board; 2-inner honeycomb core; 3-perforating the silencing plate on the outer side; 4-an outer honeycomb core; 5-a back plate; 6-female die; 7-a male die; 8-positioning pin.
For the purpose of better illustrating the embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; further, the drawings are for illustrative purposes, and terms describing positional relationships are limited to illustrative illustrations only and are not to be construed as limiting the patent.
Detailed Description
In order to make the technical solutions and advantages of the present application clearer, the technical solutions of the present application will be further clearly and completely described in the following detailed description with reference to the accompanying drawings, and it should be understood that the specific embodiments described herein are only some of the embodiments of the present application, and are only used for explaining the present application, but not limiting the present application. It should be noted that, for convenience of description, only the parts related to the present application are shown in the drawings, other related parts may refer to general designs, and the embodiments and technical features in the embodiments in the present application may be combined with each other to obtain a new embodiment without conflict.
In addition, unless otherwise defined, technical or scientific terms used in the description of the present application shall have the ordinary meaning as understood by one of ordinary skill in the art to which the present application belongs. The terms "upper", "lower", "left", "right", "center", "vertical", "horizontal", "inner", "outer", and the like used in the description of the present application, which indicate orientations, are used only to indicate relative directions or positional relationships, and do not imply that the devices or elements must have a specific orientation, be constructed and operated in a specific orientation, and when the absolute position of the object to be described is changed, the relative positional relationships may be changed accordingly, and thus, should not be construed as limiting the present application. The use of "first," "second," "third," and the like in the description of the present application is for descriptive purposes only to distinguish between different components and is not to be construed as indicating or implying relative importance. The use of the terms "a," "an," or "the" and similar referents in the context of describing the application is not to be construed as an absolute limitation on the number, but rather as the presence of at least one. The word "comprising" or "comprises", and the like, when used in this description, is intended to specify the presence of stated elements or items, but not the exclusion of other elements or items.
Further, it is noted that, unless expressly stated or limited otherwise, the terms "mounted," "connected," and the like are used in the description of the invention in a generic sense, e.g., connected as either a fixed connection or a removable connection or integrally connected; can be mechanically or electrically connected; they may be directly connected or indirectly connected through an intermediate medium, or they may be connected through the inside of two elements, and those skilled in the art can understand their specific meaning in this application according to the specific situation.
The present application is described in further detail below with reference to fig. 1 to 6.
On the one hand, the design method of the double-freedom-degree sound liner in the engine casing comprises the following steps:
the resonance frequency of the acoustic liner with two degrees of freedom is checked, and the method specifically comprises the following steps:
Figure BDA0003383962930000071
Figure BDA0003383962930000072
at frLess than or equal to f of noise frequency of engine main bodyr1Checking the resonance frequency of the two-degree-of-freedom acoustic liner;
wherein the content of the first and second substances,
frchecking a lower limit for the resonance frequency of the acoustic liner with two degrees of freedom;
fr1checking the upper limit of the resonance frequency of the acoustic liner with two degrees of freedom;
c is the equivalent sound velocity of the noise static flow field of the engine main body;
σ 1 is the perforation rate of the upper perforation hole of the inner perforated sound absorption plate 1;
σ 2 is the perforation rate of the upper perforation hole of the outer perforated sound-absorbing plate 3;
k1 is the thickness of the inner honeycomb core 2;
k2 is the thickness of the outer honeycomb core 4;
t1 is the thickness of the inner perforated sound-absorbing panel 1;
t2 is the thickness of the outer perforated sound-absorbing panel 3.
For the method for designing a two-degree-of-freedom acoustic liner in an engine case disclosed in the above embodiment, it can be understood by those skilled in the art that, in the design of the two-degree-of-freedom acoustic liner in the engine case, the two-degree-of-freedom acoustic liner is subjected to resonance frequency calibration, and when the requirement for resonance frequency calibration cannot be met, the corresponding parameters are adjusted, specifically, the perforation rate σ 1 of the sound absorbing hole in the inner perforated sound absorbing plate 1, the perforation rate σ 2 of the sound absorbing hole in the outer perforated sound absorbing plate 3, the thickness K1 of the inner honeycomb core 2, the thickness K2 of the outer honeycomb core 4, and the thickness t1 of the inner perforated sound absorbing plate 1 can be adjusted until the requirement for resonance frequency calibration is met, so as to ensure that the obtained two-degree-of-freedom acoustic liner in the engine case has better sound absorbing performance.
In some optional embodiments, in the above method for designing a two-degree-of-freedom acoustic liner in an engine casing, when Ma is less than or equal to 0.2, C is equal to C0；
In Ma>0.2, forward flow noise C ═ 1+ Ma) C0The reverse flow noise C ═ 1-Ma) C0；
Wherein the content of the first and second substances,
C0the sound velocity of the noise static flow field of the engine body.
In some optional embodiments, when the sound holes on the inner perforated sound-absorbing plate 1 and the outer sound-absorbing plate 3 are arranged in a triangle in the above-mentioned design method for the two-degree-of-freedom acoustic liner in the engine casing:
σ1＝(0.95·d1/a1)2；
σ2＝(0.95·d2/a2)2；
when the sound absorbing holes on the inner side perforated sound absorbing plate 1 and the outer side sound absorbing plate 3 are arranged in a square shape:
Figure BDA0003383962930000091
Figure BDA0003383962930000092
wherein the content of the first and second substances,
d1 is the diameter of the sound absorbing hole on the sound absorbing plate 1 with the inner side perforated;
a1 is the distance between sound absorbing holes on the sound absorbing plate 1 with inner side holes;
d2 is the diameter of the sound absorbing hole on the sound absorbing plate 3 with the perforated outer side;
a2 is the distance between sound holes on the outer perforated sound-absorbing panel 3.
In some optional embodiments, the above method for designing a two-degree-of-freedom acoustic liner in an engine casing further includes:
checking prepreg fiber integrity of the inner side perforated sound-absorbing plate 1 and the outer side perforated sound-absorbing plate 3, and specifically comprising the following steps:
when the sound absorbing holes of the inner side perforated sound absorbing plate 1 and the outer side sound absorbing plate 3 are arranged in a triangular shape, as shown in fig. 3, the weft and warp fiber integrity of the inner side perforated sound absorbing plate 1 and the outer side sound absorbing plate 3 is calculated by the following formula:
the prepreg fiber laying angle beta is 0 degree or +/-60 degrees:
weft integrity rate: (sin60 °. a-d)/(sin60 °. a);
warp integrity rate: (a-2 d)/a;
the prepreg fiber lay-up angles β are ± 30 ° and 90 °:
weft integrity rate: (a-2d)/a
Warp integrity rate: (sin60 °. a-d)/(sin60 °. a);
when the sound absorbing holes of the inner perforated sound absorbing plate 1 and the outer sound absorbing plate 3 are arranged in a square shape, as shown in fig. 4, the weft and warp fiber integrity of the inner perforated sound absorbing plate 1 and the outer sound absorbing plate 3 is calculated by the following formula:
the prepreg fiber lay-up angle β is 0 ° or 90 °:
weft integrity rate: (a-d)/a;
warp integrity rate: (a-d)/a;
the prepreg fiber lay-up angle beta is +/-45 degrees:
weft integrity rate: (a-2d sin45 °)/a;
warp integrity rate: (a-2d sin45 °)/a;
when the fiber integrity of the weft and warp of the inner side perforated sound-absorbing plate 1 is greater than the fiber integrity threshold of the inner side perforated sound-absorbing plate, the fiber integrity of the weft and warp of the inner side perforated sound-absorbing plate 1 is checked;
when the fiber integrity of the weft and warp of the outer perforated sound-absorbing plate 3 is greater than the fiber integrity threshold of the outer perforated sound-absorbing plate, the fiber integrity of the weft and warp of the inner perforated sound-absorbing plate 3 is checked;
wherein the content of the first and second substances,
a is the distance between the sound absorbing holes on the inner side perforated sound absorbing plate 1 and the outer side perforated sound absorbing plate 3;
d is the diameter of the sound absorbing hole on the inner side perforated sound absorbing plate 1 and the outer side perforated sound absorbing plate 3.
For the method for designing a two-degree-of-freedom acoustic liner in an engine casing disclosed in the above embodiment, it can be understood by those skilled in the art that, in the design of the two-degree-of-freedom acoustic liner in the engine casing, the prepreg fiber integrity of the inner perforated sound-absorbing plate 1 and the outer perforated sound-absorbing plate 3 is checked, and when the requirement for checking the fiber integrity is not met, the arrangement form of the sound-absorbing holes on the inner perforated sound-absorbing plate 1 and the outer perforated sound-absorbing plate 3, the distance a between the sound-absorbing holes, and the diameter d of the sound-absorbing hole are specifically adjusted by adjusting corresponding parameters until the requirement for checking the fiber integrity is met, so as to ensure that the obtained two-degree-of-freedom acoustic liner in the engine casing is obtained. The inner side perforated sound-absorbing plate and the outer side sound-absorbing plate have better strength and stripping resistance.
In some optional embodiments, the fiber integrity threshold of the inner perforated sound-absorbing plate in the above method for designing a two-degree-of-freedom acoustic liner in an engine casing is 50%;
the fiber integrity threshold of the outer perforated acoustical panel is 40%.
In some optional embodiments, the above method for designing a two-degree-of-freedom acoustic liner in an engine casing further includes:
when the two-degree-of-freedom acoustic liner is subjected to scaling design, the curvature of the two-degree-of-freedom acoustic liner after scaling is M times of the original curvature, the circumferential length of each section of the two-degree-of-freedom acoustic liner after scaling is not less than M times of the original length, and the number of sections is no more than the number of original sections/M.
The circumferential length of each section of the sound liner with two degrees of freedom is pi · DI/number of sound liner sections, and the curvature K is 2/DI, wherein DI is the radial dimension of the sound liner with two degrees of freedom, the smaller the curvature of the sound liner with two degrees of freedom is, the stronger the deformation resistance is, when the scaling design is performed on the sound liner with two degrees of freedom, the radial dimension of the sound liner with two degrees of freedom becomes smaller, and the curvature can increase, for example: when the 1:2 scaling design is performed on the two-degree-of-freedom acoustic liner, as shown in fig. 5, the radial dimension of the two-degree-of-freedom acoustic liner is reduced by half, the curvature of the two-degree-of-freedom acoustic liner is increased by 1 time K to 4/DI, the two-degree-of-freedom acoustic liner deforms in the direction in which the curvature becomes smaller after being subjected to the demolding, and when the scaling design is performed on the two-degree-of-freedom acoustic liner, if the curvature after the scaling of the two-degree-of-freedom acoustic liner becomes M times of the original curvature, the circumferential length of each section of the two-degree-of-freedom acoustic liner after the scaling is designed to be not less than M times of the original length, and the number of sections is equal to the original number of sections/M, so that the deformation caused by the curvature change of the two-degree-of freedom acoustic liner can be effectively reduced.
On the other hand, the double-freedom-degree sound lining in the engine case is designed by any one of the above design methods for the double-freedom-degree sound lining in the engine case, wherein the inner perforated sound-absorbing plate 1, the inner honeycomb core 2, the outer perforated sound-absorbing plate 3, the outer honeycomb core 4 and the back plate 5 are bonded by glue films.
In another aspect, a method for processing a two-degree-of-freedom acoustic liner in an engine case is provided, which is used for processing the two-degree-of-freedom acoustic liner in the engine case, and includes:
the outer honeycomb core 2, the outer perforated sound-absorbing plate 3 and the outer honeycomb core 4 are bonded by adhesive films;
punching adhesive films among the lateral honeycomb core 2, the outer side perforated sound-absorbing plate 3 and the outer side honeycomb core 4 by using a high-pressure air source to ensure that the blocking rate of sound absorbing holes on the outer side perforated sound-absorbing plate 3 is lower than the blocking rate threshold value of the sound absorbing holes of the outer side perforated sound-absorbing plate;
bonding the inner perforated sound-absorbing plate 1 and the inner honeycomb core 2 by using adhesive films;
punching a glue film between the inner side perforated sound-absorbing plate 1 and the inner side honeycomb core 2 to ensure that the blocking rate of sound absorbing holes on the inner side perforated sound-absorbing plate 1 is lower than the blocking rate threshold value of the sound absorbing holes of the inner side perforated sound-absorbing plate;
bonding the outer honeycomb core 4 and the back plate 5 by using adhesive films;
and placing the inner side perforated sound-absorbing plate 1, the inner side honeycomb core 2, the outer side perforated sound-absorbing plate 3, the outer side honeycomb core 4 and the back plate 5 in a female die 6 and a male die 7 for pressing, heating and pressurizing to melt and bond adhesive films among the inner side perforated sound-absorbing plate 1, the inner side honeycomb core 2, the outer side perforated sound-absorbing plate 3, the outer side honeycomb core 4 and the back plate 5.
For the processing method of the two-degree-of-freedom acoustic liner in the engine case disclosed in the above embodiment, it can be understood by those skilled in the art that when the two-degree-of-freedom acoustic liner in the engine case is processed, the outer honeycomb core 2, the outer perforated acoustic panel 3, and the outer honeycomb core 4 are bonded by the adhesive films, then the adhesive films between the outer honeycomb core 2, the outer perforated acoustic panel 3, and the outer honeycomb core 4 are pierced by the high pressure air source, the blocking rate of the acoustic holes in the outer perforated acoustic panel 3 is lower than the blocking rate threshold of the acoustic holes in the outer perforated acoustic panel, and simultaneously the damage to the two-degree-of-freedom acoustic liner structure can be avoided, then the adhesive films are bonded to the inner perforated acoustic panel 1 and the inner honeycomb core 2 to pierce the adhesive films between the inner perforated acoustic panel 1 and the inner honeycomb core 2, so as to ensure that the blocking rate of the acoustic holes in the inner perforated acoustic panel 1 is lower than the blocking rate threshold of the acoustic holes in the inner perforated acoustic panel, and after the outer honeycomb core 4 and the back plate 5 are bonded by glue films, placing the inner perforated sound-absorbing plate 1, the inner honeycomb core 2, the outer perforated sound-absorbing plate 3, the outer honeycomb core 4 and the back plate 5 in a female die 6 and a male die 7 for pressing, heating and pressurizing to melt and bond the glue films among the inner perforated sound-absorbing plate 1, the inner honeycomb core 2, the outer perforated sound-absorbing plate 3, the outer honeycomb core 4 and the back plate 5, and finishing the processing of the two-degree-of-freedom sound lining in the engine case.
In some optional embodiments, in the above processing method for the acoustic liner with two degrees of freedom in the engine case, the threshold value of the blockage rate of the silencing hole of the inner perforated silencing plate is 2%;
the threshold value of the blockage rate of the silencing holes of the outer perforated silencing plate is 2%.
In some optional embodiments, in the above method for processing a two-degree-of-freedom acoustic liner in an engine casing, after the inner perforated acoustic panel 1, the inner honeycomb core 2, the outer perforated acoustic panel 3, the outer honeycomb core 4, and the back panel 5 are placed in the female die 6 and the male die 7 and compressed, a plurality of positioning pins 8 are connected to the female die 6 or the male die 7, and each positioning pin 8 correspondingly extends into one bolt hole on the two-degree-of-freedom acoustic liner, so as to avoid the two-degree-of-freedom acoustic liner structure from being dislocated in the processing process, and the bolt holes existing on the two-degree-of-freedom acoustic liner are utilized, so that the two-degree-of-freedom acoustic liner structure is not damaged additionally.
The embodiments are described in a progressive manner in the specification, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
Having thus described the present application in connection with the preferred embodiments illustrated in the accompanying drawings, it will be understood by those skilled in the art that the scope of the present application is not limited to those specific embodiments, and that equivalent modifications or substitutions of related technical features may be made by those skilled in the art without departing from the principle of the present application, and those modifications or substitutions will fall within the scope of the present application.

Claims (10)

1. A design method of a double-freedom-degree sound liner in an engine case is characterized by comprising the following steps:
the resonance frequency of the acoustic liner with two degrees of freedom is checked, and the method specifically comprises the following steps:
Figure FDA0003383962920000011
Figure FDA0003383962920000012
at frLess than or equal to f of noise frequency of engine main bodyr1Checking the resonance frequency of the two-degree-of-freedom acoustic liner;
wherein the content of the first and second substances,
frchecking a lower limit for the resonance frequency of the acoustic liner with two degrees of freedom;
fr1checking the upper limit of the resonance frequency of the acoustic liner with two degrees of freedom;
c is the equivalent sound velocity of the noise static flow field of the engine main body;
sigma 1 is the perforation rate of the upper vent hole of the inner side perforated sound-absorbing board (1);
sigma 2 is the perforation rate of the upper vent hole of the outer perforated sound-absorbing board (3);
k1 is the thickness of the inner honeycomb core (2);
k2 is the thickness of the outer honeycomb core (4);
t1 is the thickness of the inner perforated sound-absorbing panel (1);
t2 is the thickness of the outer perforated sound-absorbing panel (3).
2. The method of claim 1, wherein the method further comprises the step of designing a two-degree-of-freedom acoustic liner in an engine case,
when Ma is less than or equal to 0.2, C is equal to C0；
In Ma>0.2, forward flow noise C ═ 1+ Ma) C0The reverse flow noise C ═ 1-Ma) C0；
Wherein the content of the first and second substances,
C0the sound velocity of the noise static flow field of the engine body.
3. The method of claim 1, wherein the method further comprises the step of designing a two-degree-of-freedom acoustic liner in an engine case,
when the sound absorbing holes on the inner side perforated sound absorbing plate (1) and the outer side sound absorbing plate (3) are arranged in a triangle shape:
σ1＝(0.95·d1/a1)2；
σ2＝(0.95·d2/a2)2；
when the sound absorbing holes on the inner side perforated sound absorbing plate (1) and the outer side sound absorbing plate (3) are arranged in a square shape:
Figure FDA0003383962920000021
Figure FDA0003383962920000022
wherein the content of the first and second substances,
d1 is the diameter of the sound absorbing hole on the sound absorbing plate (1) with a through hole at the inner side;
a1 is the distance between the sound absorbing holes on the sound absorbing plate (1) with the inner side perforated;
d2 is the diameter of the sound absorbing hole on the sound absorbing plate (3) with the perforated outer side;
a2 is the distance between the sound holes on the outer perforated sound-absorbing plate (3).
4. The method of claim 1, wherein the method further comprises the step of designing a two-degree-of-freedom acoustic liner in an engine case,
further comprising:
checking the prepreg fiber integrity of the inner side perforated sound-absorbing plate (1) and the outer side perforated sound-absorbing plate (3), and specifically comprising the following steps:
when the sound absorbing holes in the inner side perforated sound absorbing plate (1) and the outer side sound absorbing plate (3) are arranged in a triangular mode, the weft and warp fiber integrity of the inner side perforated sound absorbing plate (1) and the outer side sound absorbing plate (3) is calculated according to the following formula:
the prepreg fiber laying angle beta is 0 degree or +/-60 degrees:
weft integrity rate: (sin60 °. a-d)/(sin60 °. a);
warp integrity rate: (a-2 d)/a;
the prepreg fiber lay-up angles β are ± 30 ° and 90 °:
weft integrity rate: (a-2d)/a
Warp integrity rate: (sin60 °. a-d)/(sin60 °. a);
when the sound absorbing holes in the inner side perforated sound absorbing plate (1) and the outer side sound absorbing plate (3) are arranged in a square shape, the weft and warp fiber integrity of the inner side perforated sound absorbing plate (1) and the outer side sound absorbing plate (3) is calculated according to the following formula:
the prepreg fiber lay-up angle β is 0 ° or 90 °:
weft integrity rate: (a-d)/a;
warp integrity rate: (a-d)/a;
the prepreg fiber lay-up angle beta is +/-45 degrees:
weft integrity rate: (a-2d sin45 °)/a;
warp integrity rate: (a-2d sin45 °)/a;
when the fiber integrity of the weft and warp of the inner side perforated sound-absorbing plate (1) is larger than the fiber integrity threshold of the inner side perforated sound-absorbing plate, the fiber integrity of the weft and warp of the inner side perforated sound-absorbing plate (1) is checked;
when the fiber integrity of the weft and warp of the outer perforated sound-absorbing plate (3) is greater than the fiber integrity threshold of the outer perforated sound-absorbing plate, the fiber integrity of the weft and warp of the inner perforated sound-absorbing plate (3) is checked;
wherein the content of the first and second substances,
a is the distance between the upper sound absorbing holes of the inner side perforated sound absorbing plate (1) and the outer side perforated sound absorbing plate (3);
d is the diameter of the sound absorbing hole on the inner side perforated sound absorbing plate (1) and the outer side perforated sound absorbing plate (3).
5. The method of designing a two degree of freedom acoustic liner in an engine case of claim 4,
the fiber integrity threshold of the inner perforated sound-absorbing plate is 50%;
the fiber integrity threshold of the outer perforated acoustical panel is 40%.
6. The method of claim 1, wherein the method further comprises the step of designing a two-degree-of-freedom acoustic liner in an engine case,
further comprising:
when the two-degree-of-freedom acoustic liner is subjected to scaling design, the curvature of the two-degree-of-freedom acoustic liner after scaling is M times of the original curvature, the circumferential length of each section of the two-degree-of-freedom acoustic liner after scaling is not less than M times of the original length, and the number of sections is no more than the number of original sections/M.
7. The double-freedom-degree sound lining in the engine case is characterized by being designed by the design method of the double-freedom-degree sound lining in the engine case according to any one of claims 1 to 6, wherein an inner side perforated sound-absorbing plate (1), an inner side honeycomb core (2), an outer side perforated sound-absorbing plate (3), an outer side honeycomb core (4) and a back plate (5) are bonded by glue films.
8. A processing method of a double-freedom-degree acoustic liner in an engine case is characterized by comprising the following steps:
the outer honeycomb core (2), the outer perforated sound-absorbing plate (3) and the outer honeycomb core (4) are bonded by adhesive films;
punching adhesive films among the lateral honeycomb core (2), the outer side perforated sound-absorbing plate (3) and the outer side honeycomb core (4) by using a high-pressure air source to ensure that the blocking rate of sound absorbing holes on the outer side perforated sound-absorbing plate (3) is lower than the blocking rate threshold value of the sound absorbing holes of the outer side perforated sound-absorbing plate;
an inner perforated sound-absorbing plate (1) and an inner honeycomb core (2) are bonded by an adhesive film;
punching a glue film between the inner side perforated sound-absorbing plate (1) and the inner side honeycomb core (2) to ensure that the blocking rate of the sound absorbing hole on the inner side perforated sound-absorbing plate (1) is lower than the blocking rate threshold value of the sound absorbing hole of the inner side perforated sound-absorbing plate;
the outer honeycomb core (4) and the back plate (5) are bonded by a glue film;
and placing the inner side perforated sound-absorbing plate (1), the inner side honeycomb core (2), the outer side perforated sound-absorbing plate (3), the outer side honeycomb core (4) and the back plate (5) in a female die (6) and a male die (7) for pressing, heating and pressurizing to melt and bond the glue films among the inner side perforated sound-absorbing plate (1), the inner side honeycomb core (2), the outer side perforated sound-absorbing plate (3), the outer side honeycomb core (4) and the back plate (5).
9. The method of claim 8, wherein the two degrees of freedom acoustic liner machining within the engine case,
the blocking rate threshold value of the silencing holes of the inner side perforated silencing plate is 2%;
the threshold value of the blockage rate of the silencing holes of the outer perforated silencing plate is 2%.
10. The method of claim 8, wherein the two degrees of freedom acoustic liner machining within the engine case,
after an inner side perforated sound-absorbing board (1), an inner side honeycomb core (2), an outer side perforated sound-absorbing board (3), an outer side honeycomb core (4) and a back plate (5) are placed in a female die (6) and a male die (7) to be compressed, a plurality of positioning pins (8) are connected to the female die (6) or the male die (7), and each positioning pin (8) correspondingly extends into one bolt hole on a double-freedom-degree sound lining.
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