CN109376385A - The boundary layer suction-type air intake duct of controllable wall pressure gradient - Google Patents
The boundary layer suction-type air intake duct of controllable wall pressure gradient Download PDFInfo
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- CN109376385A CN109376385A CN201811087541.7A CN201811087541A CN109376385A CN 109376385 A CN109376385 A CN 109376385A CN 201811087541 A CN201811087541 A CN 201811087541A CN 109376385 A CN109376385 A CN 109376385A
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/10—Geometric CAD
- G06F30/15—Vehicle, aircraft or watercraft design
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- 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
- F02C7/04—Air intakes for gas-turbine plants or jet-propulsion plants
- F02C7/042—Air intakes for gas-turbine plants or jet-propulsion plants having variable geometry
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T17/00—Three dimensional [3D] modelling, e.g. data description of 3D objects
Abstract
Present disclose provides a kind of boundary layer suction-type air intake duct of controllable wall pressure gradient, the outlet shape of the air intake duct is circle；The import cross sectional shape of the air intake duct is made of upper and lower two half-oval shapeds；Being made of along journey cross sectional shape upper and lower two half-oval shapeds between the export and import of the air intake duct；The width along journey section is equal；The height of the upside of ellipse in the import section is greater than the elliptical height of lower half；The height of upside of ellipse at the half way section of the air intake duct is greater than the elliptical height of lower half.
Description
Technical field
This disclosure relates to aircraft gas handling system field more particularly to a kind of boundary layer suction-type of controllable wall pressure gradient
Air intake duct.
Background technique
With the continuous development of aeronautical technology, some new aircraft distribution forms are occurred gradually in the people visual field, wherein
Blended wing-body (Blended Wing Body, BWB) is exactly a kind of distribution form with wide application prospect.Blended wing-body
Body is due to the fuselage wing integrated design of height, and often half flush type is mounted on wing top or machine behind to gas handling system
Portion, this inevitably takes in the boundary-layer that fuselage or wing develop, therefore corresponding air intake duct is referred to as boundary
Layer suction-type (boundary layer ingestion, BLI) air intake duct.Compared with traditional air intake duct, BLI air intake duct is same
Using S type air intake duct, but it is with significant advantage.From aeroperformance, BLI air intake duct accelerates while sucking boundary-layer
Fuselage upper surface air-flow reduces upper surface pressure, increases lift, improves lift resistance ratio；Since speed of incoming flow reduces, engine is
It is fewer to reach the energy that enough thrust requirements need to input gas, is expected to reduce its oil consumption rate.Structurally, by
In the design of BLI engine insertion fuselage, wetted area can be further decreased, reduces frictional resistance；In addition, BLI air intake duct
For compact S-shaped bend, motor length and length of aircraft are significantly reduced, mitigates the weight of aircraft.For military aircraft
For, BLI air intake duct can effectively improve the Stealth Fighter of aircraft, this is because BLI air intake duct is mounted on fuselage afterbody, in addition
It is embedded in the S-shaped design of fuselage, radar scattering area can be effectively reduced.For seating plane, this installation side of BLI air intake duct
Formula and structure reduce the propagation forward of noise, eliminate reflection of the wing lower surface to engine exhaust noise wave.Wing body melts
Close airplane have very big potential advantages, but the embedded air intake duct of BLI of deep camber, short diffusion can exist normal pressure and
The dual adverse pressure gradient of axial compressive force causes air-flow so that air-flow is difficult to the wall surface that docile changes in air intake duct in air intake duct
Separation and whirlpool generation, additionally, due to sucking fuselage boundary-layer, be further exacerbated by outlet distortion, this necessarily will cause into
The decline of air flue aeroperformance, and then influence the performance of fan.
It is proposed that domestic and foreign scholars have conducted extensive research BLI air intake duct till now from the concept of blended wing-body, for
Its design method has following achievement.The design of early stage S-shaped air intake duct is mostly using the group of center line variation and variable area given rule
Conjunction mode is based primarily upon traditional empirical equation.The design of air intake duct is carried out according to traditional changing rule equation people
A large amount of trial needs to reasonably select center line and area according to design point parameter and state of flight when being specifically designed
The regular equation of variation, can just be such that inlet characteristic is optimal in this way.Rodriguez etc. has carried out more mesh to BLI air intake duct
Optimization design is marked, using the incoming flow angle of attack, outlet back pressure, lip molded line etc. as optimized variable, total pressure recovery coefficient, total pressure distortion
Coefficient, lift coefficient, resistance coefficient oil consumption rate etc. are used as optimization aim, are obtained by the optimization algorithm iteration based on barometric gradient
Optimal air intake duct geometry.Lee etc. carries out the optimization design of S-shaped air intake duct with the method based on adjoint matrix, and many are set
Meter parameter is indicated with adjoint matrix, equally improves the performance of air intake duct.Knight etc. develops the new method of one kind to collect
It is analyzed at state-of-the-art Fluid Mechanics Computation (Computational Fluid Dynamics, CFD), by non-uniform rational B sample
Technology carries out the design and optimization of three-dimensional S shape air intake duct in conjunction with optimum theory, and this method can carry out automatically setting again
Meter.Berrier etc. devises different the ratio of width to height, inlet mass flow-rate ratio, Reynolds number, the BLI air intake duct under import the ratio of width to height, it
After carried out numerical simulation and experimental study, obtained BLI inlet characteristic parameter with the changing rule of these variables, this to
Research afterwards has important directive significance.Zhang etc. uses Hicks Henne function as calculating center line, cross in its research
Sectional area and the basic function of change in shape optimize center line and variable area given rule, with card than proper orthogonal decomposition most
Optimal solution is generated under small square law, air intake duct aeroperformance has clear improvement after optimization.
To sum up, current common BLI Design of Inlet method is using center line and variable area given rule or on its basis
It is upper to carry out certain improvement or optimization, there is a degree of promotion for inlet characteristic, but it is important there are still one
Problem, i.e., the dynamics that do not establish directly between wall surface geometry and aerodynamic parameter are associated with, so that BLI air inlet cannot be solved very well
The problems such as flow separation that road faces is serious, outlet distortion is big, restricts the application of BLI air intake duct and grinding for BWB layout aircraft
System.
Summary of the invention
In order to solve at least one above-mentioned technical problem, the present disclosure proposes a kind of boundary layers of controllable wall pressure gradient
Suction-type air intake duct.
According to one aspect of the disclosure, the outlet shape of the boundary layer suction-type air intake duct of controllable wall pressure gradient
Shape is circle；
The import cross sectional shape of the air intake duct is made of upper and lower two half-oval shapeds；
Being made of along journey cross sectional shape upper and lower two half-oval shapeds between the export and import of the air intake duct；
The width along journey section is equal；
The height of the upside of ellipse in the import section is greater than the elliptical height of lower half；
The height of upside of ellipse at the half way section of the air intake duct is greater than the elliptical height of lower half.
According at least one embodiment of the disclosure, the area along journey section passes through the height along journey section
It is calculated, the geometry along journey section is determined by the height ratio of upper and lower two semiellipses, wherein described along journey section
Area meets following relational expression:
In above formula, A (x) indicates the area along journey section, h0Indicate the upside of ellipse height along journey section, hiIt indicates along journey
The lower semiellipse height in section, hx=ho+hiIndicate the height along journey section.
According at least one embodiment of the disclosure, when being designed to the center line of the air intake duct, using segmentation
Design, the parting expression of the center line are shown below:
In above formula, a0、a1、a2、a3Respectively indicate first half term wall surface curved dies coefficient to be asked, b0、b1、b2、b3It respectively indicates
The second half wall surface curved dies coefficient to be asked, xO1Indicate the direction import x coordinate, xO2Indicate the outlet direction x coordinate, xOcIndicate disconnected
The direction point x coordinate.
According at least one embodiment of the disclosure, the shape of the two-dimentional runner of the air intake duct is according to dimensionless groupWithIt determines, whereinFor the pressure load coefficient of the inner wall of the air intake duct,It is the two of the air intake duct
The flare factor of runner is tieed up,WithMeet following relational expression:
Wherein,WithRespectively indicate the import coordinate of the inner wall surface curve of the two-dimentional runner, outlet is sat
Mark and waypoint coordinate；WithRespectively indicate the import coordinate of the outer wall surface curve of the two-dimentional runner, outlet is sat
Mark and waypoint coordinate.
According at least one embodiment of the disclosure, the height ratio of two semiellipses up and down in the import section is 9:
1。
According to another aspect of the present disclosure, a kind of design side of the boundary layer suction-type air intake duct of controllable wall pressure gradient
Method, comprising the following steps:
Two-dimentional inner wall molded line and two-dimentional outside wall surface molded line to the air intake duct are designed respectively, obtain the air inlet
The two-dimentional wall model in road；
By adjusting the expansion of the two-dimentional runner of the pressure load coefficient and air intake duct of the inner wall of the air intake duct
Coefficient optimizes the two-dimentional wall model；
The outlet shape of the air intake duct is designed as circle, import section and the shape along journey section are designed as
It is made of upper and lower two half-oval shapeds；
Outlet, import based on the two-dimentional wall model and the air intake duct and the shape along journey section, pass through institute
It states the area along journey section and obtains the distribution mode along journey cross sectional shape, to obtain the threedimensional model of the air intake duct；
The height ratio for adjusting the semiellipse up and down at half way section, optimizes the threedimensional model；And
Based on the threedimensional model after optimization, using air intake duct geometric data establish the boundary layer suction-type of parametrization into
Air flue.
According at least one embodiment of the disclosure, to the two-dimentional inner wall molded line and outside wall surface molded line of the air intake duct
The step of being designed respectively, comprising:
The inner wall molded line and outside wall surface molded line are divided into two sections of camber lines respectively；
Curve continuous and derivable at the inner wall molded line segmentation and at the outside wall surface molded line segmentation, the inner wall
The slope and curvature of the waypoint of molded line and the outside wall surface molded line are equal.According at least one embodiment of the disclosure, institute
Stating pressure load coefficient indicates deflection situation of the air-flow at the air intake duct inner wall, and the pressure load coefficient meets as follows
Relational expression:
Wherein,WithRespectively indicate the import coordinate of the inner wall surface curve of the two-dimentional runner, outlet is sat
Mark and waypoint coordinate；
The flare factor indicates the degrees of expansion of the two-dimentional runner, and the flare factor meets following relational expression:
Wherein,WithRespectively indicate import coordinate, the exit coordinates of the outer wall surface curve of the two-dimentional runner
With waypoint coordinate.
According at least one embodiment of the disclosure, the height of the semiellipse up and down at the half way section is than meeting such as
Lower relational expression:
Wherein,Indicate the height ratio of the semiellipse up and down at the half way section,It indicates at the half way section
The height of upside of ellipse,Indicate the elliptical height of lower half at the half way section, NcIndicate the upper top in the half way section
Point, OcIndicate the half way section and center line intersection point, McIndicate the lower vertex in the half way section.
According at least one embodiment of the disclosure, it is described along journey section that acquisition is obtained by the center line of the air intake duct
The distribution mode of face shape；
The center line indicates the midpoint in the line of demarcation of the import section or more semiellipse, above and below the section Cheng Suoyou
The line in the center of circle of the midpoint in semiellipse line of demarcation and the outlet.
Detailed description of the invention
Attached drawing shows the illustrative embodiments of the disclosure, and it is bright together for explaining the principles of this disclosure,
Which includes these attached drawings to provide further understanding of the disclosure, and attached drawing is included in the description and constitutes this
Part of specification.
Fig. 1 is the boundary layer suction-type air inlet according to the controllable wall pressure gradient of at least one embodiment of the disclosure
The double stator leaf grating schematic diagram in road.
Fig. 2 is the boundary layer suction-type air inlet according to the controllable wall pressure gradient of at least one embodiment of the disclosure
The air intake duct two dimension wall model of the simplification in road.
Fig. 3 is the boundary layer suction-type air inlet according to the controllable wall pressure gradient of at least one embodiment of the disclosure
The two dimensional model of the boundary layer suction-type air intake duct in road.
Fig. 4 is the boundary layer suction-type air inlet according to the controllable wall pressure gradient of at least one embodiment of the disclosure
Road along journey Arbitrary Shape Cross Section schematic diagram.
Fig. 5 is the boundary layer suction-type air inlet according to the controllable wall pressure gradient of at least one embodiment of the disclosure
Road changes schematic diagram along journey cross sectional shape.
Fig. 6 is the boundary layer suction-type air inlet according to the controllable wall pressure gradient of at least one embodiment of the disclosure
The import section molded line schematic diagram in road.
Fig. 7 is the boundary layer suction-type air inlet according to the controllable wall pressure gradient of at least one embodiment of the disclosure
Road it is differentTwo-dimentional wall surface molded lines under value.
Fig. 8 is the boundary layer suction-type air inlet according to the controllable wall pressure gradient of at least one embodiment of the disclosure
RoadShi ButongCorresponding air intake duct three-dimensional model diagram.
Fig. 9 is the boundary layer suction-type air inlet according to the controllable wall pressure gradient of at least one embodiment of the disclosure
The total divisor in road test lower total pressure recovery coefficient withWithVariation diagram.
Figure 10 be according to the boundary layer suction-type of the controllable wall pressure gradient of at least one embodiment of the disclosure into
Air flueShi ButongCorresponding total pressure recovery coefficient and total pressure distortion charts for finned heat.
Figure 11 be according to the boundary layer suction-type of the controllable wall pressure gradient of at least one embodiment of the disclosure into
The comparison diagram of wall surface molded line inside and outside the Pressure control model and conventional model of air flue.
Figure 12 be according to the boundary layer suction-type of the controllable wall pressure gradient of at least one embodiment of the disclosure into
The three-dimensional modeling schematic diagram of the Pressure control model BLI air intake duct of air flue.
Figure 13 be according to the boundary layer suction-type of the controllable wall pressure gradient of at least one embodiment of the disclosure into
The conventional model plane of symmetry velocity vector distribution map of air flue.
Figure 14 be according to the boundary layer suction-type of the controllable wall pressure gradient of at least one embodiment of the disclosure into
The Pressure control model plane of symmetry velocity vector distribution map of air flue.
Figure 15 be according to the boundary layer suction-type of the controllable wall pressure gradient of at least one embodiment of the disclosure into
The Pressure control model of air flue and the outlet stagnation pressure cloud atlas of conventional model.
Figure 16 be according to the boundary layer suction-type of the controllable wall pressure gradient of at least one embodiment of the disclosure into
The performance comparison figure of Pressure control model and conventional model under 25% inlet distortion of air flue.
Specific embodiment
The disclosure is described in further detail with embodiment with reference to the accompanying drawing.It is understood that this place
The specific embodiment of description is only used for explaining related content, rather than the restriction to the disclosure.It also should be noted that being
Convenient for description, part relevant to the disclosure is illustrated only in attached drawing.
It should be noted that in the absence of conflict, the feature in embodiment and embodiment in the disclosure can
To be combined with each other.The disclosure is described in detail below with reference to the accompanying drawings and in conjunction with embodiment.
In order to which the mathematical physics established between wall pressure distribution and Curvature varying contacts, it is necessary to comprehensively consider S-shaped air inlet
Road two dimension wall surface locality normal direction curvature and influence of the one-dimensional area distributions to wall pressure distribution.Super across sound aircraft air intake duct is past
Toward being all diffusion channel, it is being in axially counter-pressure distribution that the introducing of axial pressure gradient, which will lead to inside and outside wall surface, at this point, in axial direction
Under pressure and the dual adverse pressure gradient effect of normal pressure, how to optimize air intake duct axial " load " distribution, control S-shaped air intake duct wall
The rule of surface pressure distribution and Curvature varying just becomes the key problem that S-shaped Design of Inlet obtains good aeroperformance.
For BLI air intake duct, air-flow is flowed into export to flow out successively to undergo from import and deflect twice, in runner front half section
Certain angle is deflected by axial admission first, then deflects into axial outlet again by the runner second half section.Existing research shows that
BLI air intake duct mean curvature variation size, front and back curvature distribution and flow to area distributions can convection current road normal pressure gradient and
Axial pressure gradient affects, and also directly decides the deflection angle of air-flow.From physical essence, BLI air intake duct and leaf
Turbine stator leaf grating is similar in terms of internal gas flow flowing, therefore the two-dimensional flow of BLI air inlet passage center stream interface completely may be used
To be equivalent to the superposition of two rows of stator diffuser grid S1 stream interface flowings.The design method of middle camber line in Design of Cascade is used for reference to design
The two-dimentional wall surface molded line of BLI air intake duct, while can also be by arbitrarily adjusting front and rear row leaf grating bent angle size and inlet and outlet face
Product changes to control the normal direction and axial gradient changing rule of air intake duct, to realize the Parametric designing to air intake duct.
In an optional embodiment of the disclosure, the arbitrarily middle camber line of the design reference leaf grating of air intake duct wall surface molded line
Design philosophy, while no longer using simple axial symmetry it is assumed that inner wall and outside wall surface molded line are designed respectively, that is, it uses
The thought of camber line " dividing half " design in forward and backward row's leaf grating.As shown in Figure 1, using for reference the design method of middle camber line in Design of Cascade
To design the two-dimentional wall surface molded line of BLI air intake duct.BLI air inlet passage center stream interface can be equivalent to camber line in two rows of stator leaf gratings and be formed
Two-dimentional runner, the middle camber line of front and rear row leaf grating shown in Fig. 1 is designed respectively, then approximate can obtain it is as shown in Figure 2 into
Air flue two dimension wall model, wherein N1-Nc、M1- Mc indicates camber line in front-seat leaf grating, Nc-N2、Mc-M2It then indicates in heel row leaf grating
Camber line.Specifically, it is assumed that the axial length of upstream leaf grating and downstream leaf grating is equal, as shown in figure 3, for Inlet wall surface
The design of two-dimentional molded line can determine the geometrical condition of import and export by basic air inlet track data.In addition, being segmented in leaf grating
Locate curve continuous and derivable, therefore waypoint position coordinates, slope and curvature are equal.It can thus be concluded that following 7 known conditions: import
Coordinate, import slope, exports continuous slope, anterioposterior curve waypoint, waypoint slope rate continuity and waypoint curvature at exit coordinates
Continuously.If a definite condition can be re-introduced into, the forward and backward half way wall surface molded line of air intake duct has 4 known conditions, can be true
Thus fixed 4 undetermined coefficients can then establish 3 order polynomial models to it respectively and guarantee that model is closed.Being segmented cubic equation can
It is described as following formula 1:
Wherein, xO1Indicate the direction import x coordinate, xO2Indicate the outlet direction x coordinate, xOcIndicating breakpoint, (half way section is in
Heart line intersection point) direction x coordinate；a1、a2、a3、a0Respectively indicate the first half term wall surface curved dies coefficient to be asked of air intake duct；b1、b2、
b3、b0Respectively indicate the second half wall surface curved dies coefficient to be asked.
According to the equation group of the available such as following formula 2 of above-mentioned 7 known conditions:
Wherein, ZM1、ZN1Respectively indicate the inner wall surface curve of two-dimentional runner and the import coordinate of outer wall surface curve, ZM2、ZN2Point
Not Biao Shi the two-dimentional inner wall surface curve of runner and the exit coordinates of outer wall surface curve, x1、x2、xcIt respectively indicates import, outlet, break
The direction x coordinate at point (half way section and center line intersection point).
Inner wall and the segmental cubic polynomials curve of outside wall surface have 8 unknowm coefficients, i.e. a0-a3And b0-b3, but mesh
Preceding only 7 boundary conditions need additionally to increase a boundary condition to allow equation 1 to close.As shown in figure 3, certain
Inlet and outlet under the conditions of, the setting angle of leaf grating influences the deflection angle of air-flow, and then influences the gas of front-seat leaf grating and heel row leaf grating
Dynamic load.The tangent value of leaf grating established angle is expressed as follows formula 3 and 4:
Wherein, tan (χ11)、tan(χ12) the established angle tangent value of inner wall front row leaf grating and heel row leaf grating is respectively indicated,
tan(χ21)、tan(χ22) the established angle tangent value of outside wall surface front row leaf grating and heel row leaf grating is respectively indicated,Indicate two-dimensional flow
The waypoint coordinate of the inner wall surface curve in road,Indicate that the waypoint coordinate of the outer wall surface curve of two-dimentional runner, L indicate leaf grating
Axial length.
With the tangent value of front-seat leaf grating established angle divided by the tangent value of heel row leaf grating, then two dimensionless groups are obtained, such as
Following formula 5 and 6:
Wherein,WithRespectively indicate the import coordinate of the inner wall surface curve of two-dimentional runner, exit coordinates and point
Section point coordinate；WithRespectively indicate import coordinate, exit coordinates and the waypoint of the outer wall surface curve of two-dimentional runner
Coordinate.
Due to normal pressure gradient variation it is directly related to deflection angle of the air-flow in runner, i.e., with inside and outside wall surface
The Curvature varying of molded line is related.AndDeflection situation of the air-flow at inner wall can be indicated, thus before quantitative description air intake duct
The relationship of second half section normal pressure gradient and Curvature varying, while determining the pressure load distribution of half way before and after inner wall, because
HereIt is defined as the load coefficient of front and back half way.On the other hand, air intake duct along journey area distributions determines axial pressure
Force gradient, so that the aeroperformance of air intake duct is significantly affected, under the conditions of specific inner wall,Variation influence half way position
The area in place section is set, to influence the variation along journey area of section.As half way area of section (AC) it is greater than intake area
(A1) and exit area (A2) when, it is meant that air intake duct two dimension runner is first expanded to be shunk again.Work as ACGreater than A1And it is less than A2When,
Mean that air intake duct two dimension runner is expanding channel.Work as ACLess than A1And it is greater than A2When, it is meant that air intake duct two dimension runner is first shunk
Further expansion, thus hereIt is defined as flare factor.By adjusting load coefficientAnd flare factorValue, can
To realize the optimization of two-dimentional S-shaped air intake duct.
BLI air intake duct is usually oval or hyperelliptic along journey cross sectional shape, and import is similar to " D " shape so that it is convenient to attached
The intake of surface layer.In an optional embodiment of the disclosure, it will be designed as being made of upper and lower double semiellipses along journey section, give
Fixed elliptical height up and down compares for 9:1.Air intake port (fan inlet) be circular section, therefore the three-dimensional structure of air intake duct be from
Import double-ellipse cross-section smoothly transits to outlet circular section.It enables air intake duct equal along Cheng Kuandu, to establish the three-dimensional of S-shaped air intake duct
Model needs know the shape along journey section.As shown in figure 4, the midpoint O in upper and lower semiellipse line of demarcation is regarded as " the center in section
Point " connects and composes " center line " of air intake duct along the central point in the section Cheng Suoyou and the center of circle of outlet.As shown in figure 5, bent
Line O1OCO2It is the center line of BLI air intake duct.When center line is decided, so that it may which the three-dimensional geometry for obtaining air intake duct opens up benefit
Structure.According to the calculation formula along journey area of section, as shown in following formula 7 and 8, air intake duct can be by along journey along journey area of section A (x)
Height hxIt is calculated, the geometry of arbitrary section is only determined by the height ratio ho/hi of upper and lower semiellipse.
hx=ho+hiFormula 8
Wherein, D indicates the boundary line length of semiellipse up and down.
The design for using for reference BLI air intake duct two dimension wall surface, to air intake duct upstream center line O1OcWith downstream central line OcO2Respectively
It is designed, the parting expression of center line is as shown in Equation 9:
It is similar to the solution mode of inside and outside wall surface molded line, 7 equation groups can be constructed by known conditions, it is only necessary to draw
Entering a boundary condition can be such that equation group closes.Here dimensionless group distribution coefficient is introduced On at half way section
The elliptical height ratio of lower half, expression formula is as shown in following formula 10:
Wherein,Indicate the height of the upside of ellipse at half way section,Indicate the elliptical height of lower half at half way section
Degree, NcIndicate the upper vertex in half way section, OcIndicate half way section and center line intersection point, McIndicate the lower vertex in half way section.
Any given one groupJust can obtain it is a kind of along journey cross sectional shape distribution mode, therefore, by adjustingIt may be implemented
The optimization of three-dimensional S shape air intake duct model.
It is several using specific air intake duct the following detailed description of the method for building up based on above-mentioned air intake duct three-dimensional parametric modeling
What data establishes the BLI air intake duct of parametrization, and optimizes under the BLI effect of 25% boundary-layer intake.
The disclosure is required with meeting design discharge when average flight state as design point, design point design parameter such as 1 institute of table
Show:
1 BLI Design of Inlet point parameter of table
According to design point condition, inlet throat area, import and export offset distance Δ H, air intake duct axial length L can be determined
Equal parameter values.Wherein, consider that the range of L/D in placement constraint grade bibliography, L value are 3.8m.The selection of △ H is mainly joined
The value in pertinent literature is examined, L/D ≈ 2.2 in present embodiment, △ H/L ≈ 0.18, while choosing venturi Mach number Mth and being
0.75 is designed, and taking the flow gross blockage factor of Fighter Inlet is 1.01, the specific basic geometric parameters of available air intake duct
Number is as shown in table 2:
2 BLI air intake duct basic geometric parameters of table
For air intake duct embedded for BLI, it is contemplated that it is mounted on fuselage back and is embedded in fuselage intake fuselage surface
The characteristics of boundary-layer, entry shape use hyperelliptic or Ellipse design.For the aeroperformance for improving the embedded air intake duct of BLI, drop
Influence of the low Fighter Inlet shape to air intake duct, disclosure Fighter Inlet shape are designed using double semiellipses and are carried out to it
Optimization.To match fan, air intake port is designed using full circle.Therefore, the embedded air intake duct of the BLI of the disclosure is double semiellipses
0.863m is kept to the transition of full circle, and along Cheng Kuandu (R2).According to ellipse area formula it is available along journey area of section with
The relationship of depth of section, such as following formula 11:
Wherein, huFor height oval on import section, hdFor height oval under import section, R2It is air intake duct along Cheng Kuandu,
H is entrance height.Fighter Inlet section molded line schematic diagram is as indicated with 6.
According to table 2, inlet -duct area A1=1.7808m2, it is known that air intake duct is along Cheng Kuandu R2=0.863m, therefore can find out
Fighter Inlet height h=1.3134.Due to the intake of boundary-layer, the ratio between the upper and lower oval height in import section affect into
The aeroperformance of air flue, if hu/hd=K, present embodiment takes K=9.
According to above-mentioned BLI air intake duct three-dimensional parametric modeling method for building up, under specific air intake duct geometrical conditions
Carry out the moulding of air intake duct.
Inside and outside wall surface molded line and " center line " are subjected to segment design, enable the coordinate x=0 at air intake duct half way position, it is right
Claim the coordinate y=0 at section, according to the above-mentioned air intake duct basic geometric parameters acquired, the import and export of available three molded line
Coordinate.Introduce 3 control parameters The curved dies of three control parameters can be obtained, to obtain air inlet
The parameterized model in road.
If Fig. 7 is three kinds differentThe lower inside and outside wall surface molded lines of air intake duct is combined, can intuitively be found outDetermine the curved whole deflection situation of air intake duct S and along journey area of section situation of change.
As Fig. 8 isDifferentIt is worth corresponding air intake duct three-dimensional parametric modeling,
It can be seen thatInfluence above and below import semiellipse to outlet full circle transient condition,Edge can be all caused when too large or too small
The variation of journey cross sectional shape is violent.
Using correlation values means and genetic algorithm, above-mentioned 3 control parameters are selectedWith total pressure recovery
Coefficient and outlet distortion factor carry out relevant optimization as air intake duct internal flow characteristics parameter is measured.
Total pressure recovery coefficient σ and outlet distortion factor DC (θ) formula such as following formula 12 and 13:
Wherein,Expression is worked off one's feeling vent one's spleen the equal stagnation pressure of levelling；Indicate undisturbed section air-flow stagnation pressure.
Wherein,Indicate outlet average total pressure；Indicate θ0Outlet fan-shaped region average total pressure, this reality
The mode of applying takes 150 °；Indicate that outlet is averaged dynamic pressure.
Firstly, observationWithInfluence to inlet characteristic.It is tentatively selected using the DOE approach for optimizing super Latin square
It takes so that the optimal parameter combination of two-dimentional air intake duct model, testing site number is taken as 80, total pressure recovery coefficient highest ten
Design point is correspondingWithIt is averaged, obtains?It is interior to take a testing site every 0.1,It is interior to take a test every 0.1
Point, by total divisor design to obtain total pressure recovery coefficient withWithThe three-dimensional figure of variation, as shown in Figure 9.It can from Fig. 9
To find out, the total pressure recovery coefficient of two-dimensional parameter model withWithChange and there are certain rules.In a certain range
It is interior, withWithIncrease, total pressure recovery coefficient first increases and then decreases, therefore can find in the range optimal
Parameter combination makes two-dimentional inlet characteristic best.WithIt compares,It is the principal element for influencing total pressure recovery coefficient.WhenThe total pressure recovery coefficient of two dimensional model is obviously improved when close to 0, and When total pressure recovery system
Number reaches peak value.The mean parameter taken after the parameter combination and optimal Latin hypercube experimental design is close, to demonstrate
The validity of mean parameter method is taken with optimal Latin hypercube experimental design.
Secondly, observationInfluence to inlet characteristic.It enablesAdjustmentValue can
To obtain differenceThe calculated result of lower threedimensional model.Total pressure recovery coefficient and total pressure distortion coefficient as shown in Figure 10 with's
Changing rule.It can be seen that withIncrease, total pressure recovery coefficient first increases to be reduced afterwards, and total pressure distortion coefficient first reduces to be increased afterwards.
?Neighbouring inlet characteristic is best, too low or excessively highWill inlet characteristic be declined.
Then, structure adjustingWithValue, BLI air intake duct is optimized.When being optimized using Isight
The preliminary selection for carrying out these three parameters by the experimental design of optimal Latin hypercube first, is then carried out using genetic algorithm
Optimization, parameter area include the parameter combination tentatively chosen.Testing site number is taken as 80 when optimal Latin hypercube experimental design,
Highest ten design points of total pressure recovery coefficient are correspondingWithIt is averaged, obtains respectivelyIt is taken respectively with the range of three parameters when genetic algorithm optimization
ForOptimization object function is total pressure recovery
Coefficient.Optimum results areTotal pressure recovery coefficient at this time
It is 0.9586.
Two geometrical models are designed using unified geometric parameter (inlet -duct area, length, offset distance, section molded line etc.).One
Using the control wall pressure distribution method after optimization, abbreviation Pressure control model (Pressure Control Model,
PCM)；Secondly using conventional centre lines, variable area given rule empirical equation choosing method as benchmark model, center line and area
It is all made of the comparable changing rule of emergency, abbreviation conventional model (Traditional, T).By the BLI air intake duct (pressure after optimization
Controlling model/PCM) with traditional design method design BLI air intake duct (conventional model/T) compare.Figure 11 is conventional model
It is compared with Pressure control model two dimension wall surface molded line.Wherein dotted portion representative pressure Controlling model, bold portion represent tradition
Model.It can be seen that the result of two kinds of design methods has a visibly different wall surface curvature variation, Pressure control model due to
Strict control imports and exports slope, curvature, and apparent curvature variation is presented in internal and external walls face molded line, therefore air-flow flows through wall surface
When, the deceleration, acceleration effect at curvature obviously protrudes relatively, this helps to provide radial pressure ladder appropriate to air-flow
Degree generated centrifugal force when being turned round with airflow balancing.Delay after urgency before the variable area given rule of Pressure control model is intended to, it is preceding
Half way undertakes biggish diffusion, has mitigated the adverse pressure gradient of the second half.Pressure control model BLI air intake duct three-dimensional modeling such as Figure 12
It is shown.
Present embodiment is by the BLI air intake duct of controllable wall pressure gradient and conventional model BLI air intake duct, in flow separation
It is compared with two aspects of outlet distortion, while being also compared for total pressure recovery coefficient and outlet distortion factor.Figure
13 and Figure 14 is that conventional model and Pressure control model are distributed in the velocity vector of central cross-section, it can be seen that in big boundary-layer
Both occurs more serious flow separation phenomenon under intake, but the separation of Pressure control model attaches wall again earlier
Face, this makes Pressure control model relatively more uniform in the VELOCITY DISTRIBUTION of outlet.Figure 15 is the outlet stagnation pressure of two kinds of models
Cloud atlas, it can be seen that the area of the Pressure control model low-pressure area after optimization is slightly less than conventional model.
In order to compare the difference of disclosure design method and traditional design method, present embodiment to above two model into
It has gone numerical simulation, has calculated total pressure recovery coefficient and outlet total pressure distortion coefficient under different operating conditions.Figure 16 is two kinds of models
Total pressure recovery coefficient and total pressure distortion coefficient with discharge coefficient change curve, it can be seen that the S based on wall pressure control
Shape air intake duct model has lower total pressure distortion and higher total pressure recovery coefficient than the BLI air intake duct that conventional method designs, and
And biggest quality flow can be improved, total pressure recovery coefficient improves 0.41% at design point, and total pressure distortion coefficient reduces
7.6%.
In conclusion the disclosure is associated with by the dynamics established between wall surface geometry and aerodynamic parameter, control wall is formed
BLI air intake duct is carried out Parametric designing and optimized, the controllable wall surface of acquisition by the BLI Design of Inlet method of surface pressure distribution
The BLI air intake duct of barometric gradient can inhibit flow separation situation well, weaken outlet distortion.
It will be understood by those of skill in the art that above embodiment is used for the purpose of clearly demonstrating the disclosure, and simultaneously
Non- be defined to the scope of the present disclosure.For those skilled in the art, may be used also on the basis of disclosed above
To make other variations or modification, and these variations or modification are still in the scope of the present disclosure.
Claims (10)
1. a kind of boundary layer suction-type air intake duct of controllable wall pressure gradient, which is characterized in that
The outlet shape of the air intake duct is circle；
The import cross sectional shape of the air intake duct is made of upper and lower two half-oval shapeds；
Being made of along journey cross sectional shape upper and lower two half-oval shapeds between the export and import of the air intake duct；
The width along journey section is equal；
The height of the upside of ellipse in the import section is greater than the elliptical height of lower half；
The height of upside of ellipse at the half way section of the air intake duct is greater than the elliptical height of lower half.
2. air intake duct according to claim 1, which is characterized in that the area along journey section is by described along journey section
Height be calculated, the geometry along journey section is determined by the height ratio of upper and lower two semiellipses, wherein the edge
Journey area of section meets following relational expression:
In above formula, A (x) indicates the area along journey section, h0Indicate the upside of ellipse height along journey section, hiIt indicates along journey section
Lower semiellipse height, hx=ho+hiIndicate the height along journey section.
3. air intake duct according to claim 1 or 2, which is characterized in that when being designed to the center line of the air intake duct,
Using segment design, the parting expression of the center line is shown below:
In above formula, a0、a1、a2、a3Respectively indicate first half term wall surface curved dies coefficient to be asked；b0、b1、b2、b3It respectively indicates later half
Journey wall surface curved dies coefficient to be asked, xO1Indicate the direction import x coordinate, xO2Indicate the outlet direction x coordinate, xOcIndicate the breakpoint side x
To coordinate.
4. air intake duct according to claim 3, which is characterized in that the shape of the two-dimentional runner of the air intake duct is according to immeasurable
Guiding principle parameterWithIt determines, whereinFor the pressure load coefficient of the inner wall of the air intake duct,For the air inlet
The flare factor of the two-dimentional runner in road,WithMeet following relational expression:
Wherein,WithRespectively indicate the import coordinate of the inner wall surface curve of the two-dimentional runner, exit coordinates and point
Section point coordinate；WithRespectively indicate the import coordinate of the outer wall surface curve of the two-dimentional runner, exit coordinates and point
Section point coordinate.
5. air intake duct according to claim 4, which is characterized in that
The height ratio of two semiellipses up and down in the import section is 9:1.
6. a kind of design method of the boundary layer suction-type air intake duct of controllable wall pressure gradient, which is characterized in that including following
Step:
Two-dimentional inner wall molded line and two-dimentional outside wall surface molded line to the air intake duct are designed respectively, obtain the air intake duct
Two-dimentional wall model；
By adjusting the flare factor of the two-dimentional runner of the pressure load coefficient and air intake duct of the inner wall of the air intake duct,
Optimize the two-dimentional wall model；
The outlet shape of the air intake duct is designed as circle, import section and the shape along journey section are designed as by upper
Lower two half-oval shapeds composition；
Outlet, import based on the two-dimentional wall model and the air intake duct and the shape along journey section, pass through the edge
The area in journey section obtains the distribution mode along journey cross sectional shape, to obtain the threedimensional model of the air intake duct；
The height ratio for adjusting the semiellipse up and down at half way section, optimizes the threedimensional model；And
Based on the threedimensional model after optimization, the boundary layer suction-type air inlet of parametrization is established using air intake duct geometric data
Road.
7. according to the method described in claim 6, it is characterized in that, two-dimentional inner wall molded line and outside wall surface to the air intake duct
The step of molded line is designed respectively, comprising:
The inner wall molded line and outside wall surface molded line are divided into two sections of camber lines respectively；
Curve continuous and derivable at the inner wall molded line segmentation and at the outside wall surface molded line segmentation, the inner wall molded line
It is equal with the slope of the waypoint of the outside wall surface molded line and curvature.
8. method according to claim 6 or 7, which is characterized in that
The pressure load coefficient indicates deflection situation of the air-flow at the air intake duct inner wall, and the pressure load coefficient is full
The following relational expression of foot:
Wherein,WithRespectively indicate the import coordinate of the inner wall surface curve of the two-dimentional runner, exit coordinates and point
Section point coordinate；
The flare factor indicates the degrees of expansion of the two-dimentional runner, and the flare factor meets following relational expression:
Wherein,WithRespectively indicate the import coordinate of the outer wall surface curve of the two-dimentional runner, exit coordinates and point
Section point coordinate.
9. according to the method described in claim 8, it is characterized in that, the height of the semiellipse up and down at the half way section is than full
The following relational expression of foot:
Wherein,Indicate the height ratio of the semiellipse up and down at the half way section,Indicate that the upper half at the half way section is ellipse
Round height,Indicate the elliptical height of lower half at the half way section, NcIndicate the upper vertex in the half way section, OcTable
Show the half way section and center line intersection point, McIndicate the lower vertex in the half way section.
10. according to the method described in claim 9, it is characterized in that,
It is obtained by the center line of the air intake duct and obtains the distribution mode along journey cross sectional shape；
The center line indicates the midpoint, ellipse along the upper lower half in the section Cheng Suoyou in the import section line of demarcation of semiellipse up and down
The line in the center of circle at the midpoint and outlet in circle line of demarcation.
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