Plane embedded type air inlet channel considering comprehensive performance under multiple working conditions and optimization method

Abstract

The invention relates to a plane embedded type air inlet channel considering comprehensive performance under multiple working conditions and an optimization method, belongs to the technical field of aircrafts, and solves the problem that the comprehensive performance of the air inlet channel in a cruise state, different engine working conditions and external flow field conditions is poor in measurement. And no good improvement strategy is provided. The plane embedded type air inlet channel comprises a lip, an inlet flow guide section and a diffusion section. The inlet flow guide section is arranged between the lip and the diffusion section, and the joint of the inlet flow guide section and the diffusion section is a first interface; an outlet section is arranged at the joint of the diffusion section and the aircraft engine inlet; a second interface is arranged at the joint of the lip and the aircraft fuselage.

Description

Technical Field

[0001] The present invention belongs to the technical field of aircraft, and in particular relates to a planar embedded air inlet taking into account comprehensive performance under multiple working conditions and an optimization method. Background Art

[0002] Compared with traditional precision strike weapons, such as precision-guided bombs and cruise missiles, cruise missiles have shown their unique advantages, such as long-term air lingering ability and flexible target selection. These characteristics make cruise missiles an efficient means of precision strikes on key battlefield nodes and high-value targets.

[0003] The performance of the air inlet directly affects the propulsion efficiency and working stability of the engine, and plays a vital role in the flight performance of the jet cruise missile. The plane embedded air inlet can effectively shield the fan blades and compressor blades downstream of the air inlet, significantly reducing the radar scattering area of ​​the aircraft, and has a better stealth effect than the conventional S-bend air inlet.

[0004] However, since the plane embedded air inlet has no boundary layer separator, and its lip side edge will produce a suction effect on the boundary layer of the front fuselage, it is easy to suck in the low-energy boundary layer of the front fuselage of the aircraft. After these low-energy boundary layers enter the air inlet, the airflow in the air inlet will be greatly distorted, reducing the total pressure recovery coefficient of the air inlet, which is not conducive to the stable operation of the engine. Therefore, optimizing the design of the plane embedded air inlet will help improve the stealth performance of the aircraft, improve the engine propulsion efficiency, and expand the flight envelope of the cruise missile, which has important practical significance.

[0005] The existing optimization design methods for planar embedded inlet ducts are mainly aimed at the performance of the inlet duct under the cruise state of the aircraft. Considering the mission requirements of jet cruise missiles, it is necessary to ensure that the engine can work stably when it is in the cruise state, performing maneuvers and being disturbed by the outside world. This requires that the inlet duct has a smaller intake distortion and a larger total pressure recovery coefficient not only at the design point of the cruise state, but also under different engine operating conditions and external flow field conditions (mainly angle of attack and sideslip angle). Therefore, it is necessary to establish a more comprehensive inlet aerodynamic performance evaluation method to measure the comprehensive performance of the inlet duct under different working conditions, and optimize the design of the inlet duct with the comprehensive performance under multiple working conditions as the goal. Summary of the invention

[0006] In view of the above problems, the present invention provides a planar embedded inlet and an optimization method that considers the comprehensive performance under multiple working conditions. The problem that the comprehensive performance of the inlet under the cruise state, different engine working conditions and external flow field conditions (mainly the angle of attack and sideslip angle) is poor and there is no better improvement strategy when improving the comprehensive performance of the inlet under multiple working conditions is solved.

[0007] The present invention provides a planar embedded air inlet that takes into account comprehensive performance under multiple working conditions, comprising a lip, an inlet guide section and a diffuser section; the inlet guide section is arranged between the lip and the diffuser section, and the connection between the inlet guide section and the diffuser section is interface 1; an outlet section is arranged at the connection between the diffuser section and the aircraft engine inlet; and interface 2 is arranged at the connection between the lip and the aircraft fuselage.

[0008] Optionally, the ratio of the cross-sectional area of ​​the second interface to the cross-sectional area of ​​the outlet cross section is the pressure diffusion ratio.

[0009] Optionally, the angle between the side wall of the inlet guide section and a line parallel to the axis of the inlet guide section is the lip side angle.

[0010] The present invention also provides a method for optimizing a planar embedded air intake duct that takes into account comprehensive performance under multiple working conditions, and optimizes the aforementioned planar embedded air intake duct, which is characterized by the following specific steps:

[0011] S1. Establish a parametric surface model of the plane embedded air inlet;

[0012] S2. Initialize the parameters of the parametric surface model of the plane embedded air inlet;

[0013] The parameterized surface model includes the first-stage model parameters and the second-stage model parameters;

[0014] S3. Let k = 0. When k = 0, it is the initial moment of the first stage;

[0015] S4. Based on the parameters of the parametric surface model of the plane embedded air inlet at the kth moment and the parametric surface model of the plane embedded air inlet in step S1, a first-stage plane embedded air inlet at the kth moment is generated; meshing the plane embedded air inlet surface model at the kth moment to obtain a first-stage mesh at the kth moment;

[0016] S5. Based on the first-stage grid and the first-stage boundary conditions at the k-th moment in step S4, aerodynamic numerical simulation is performed on the air inlet to obtain the flow field data at each point on the outlet cross section of the air inlet at the k-th moment;

[0017] S6. Input the flow field data obtained in S5 into the simulation data post-processing module to obtain the first stage evaluation index at the kth moment;

[0018] S7. Based on the first-stage evaluation index, determine whether the first-stage embedded air intake duct at the kth moment has reached the first-stage optimization target. If it has reached the first-stage optimization target, obtain the first-stage optimized air intake duct and proceed to step S8. If it has not reached the first-stage optimization target, obtain the first-stage model parameters at the k+1th moment, set k=k+1, and return to step S4.

[0019] S8. Initializing the second stage model parameters of the air intake after the first stage optimization;

[0020] S9. Let t = 0. When t = 0, it is the initial time of the second stage;

[0021] S10. Based on the second stage model parameters of the first stage optimized air intake at time t and the parameterized surface model of the plane embedded air intake in step S1, a second stage plane embedded air intake at time t is generated;

[0022] S11. Meshing the second-stage planar embedded air inlet at time t to obtain the second-stage mesh at time t;

[0023] S12. Based on the second-stage grid and the second-stage boundary conditions at the t-th time in step S11, a batch of aerodynamic numerical simulations are performed on the air intake duct to obtain the total pressure at each point on the outlet cross section of the air intake duct under the corresponding boundary conditions and the second-stage grid at the t-th time;

[0024] S13. The total pressure at each point on the outlet cross section of the inlet duct under the second-stage grid corresponding to the boundary conditions and the t-th time is input into the simulation data post-processing module, and the post-processing module outputs the evaluation index of the second-stage inlet duct at the t-th time;

[0025] S14. Based on the evaluation index of the second-stage air intake duct, determine whether the performance of the second-stage air intake duct at the t-th time reaches the second-stage optimization target. If the second-stage optimization target is reached, obtain the optimized plane embedded air intake duct surface model and proceed to step S15. If the second-stage optimization target is not reached, obtain the second-stage model parameters of the first-stage optimized air intake duct at the t+1th time, set t=t+1, and return to step S10.

[0026] S15. Output the optimized plane embedded air inlet surface model.

[0027] Optionally, the first stage model parameters include a diffuser centerline shape control coefficient and a diffuser cross-sectional area distribution law control coefficient;

[0028] The second stage model parameters include lip side angle and diffusion ratio.

[0029] Optionally, the first-stage boundary condition in step S5 is the state of the external gas in the air inlet when the aircraft is in a cruising state.

[0030] Optionally, the process data in step S5 are the total pressure and dynamic pressure of the flow field at each point on the outlet cross section of the inlet duct at the kth moment and the far-field free flow total pressure of the flow field outside the inlet duct.

[0031] Optionally, the first stage evaluation index at the kth moment includes the inlet total pressure distortion index DC60 k and total pressure recovery coefficient PR k .

[0032] Optionally, the parameters of the parameterized surface model of the planar embedded air inlet include coefficients of the first-stage air inlet centerline expression and coefficients of the diffuser section area distribution law expression.

[0033] Optionally, the second stage evaluation index includes the performance index at the inlet design point of the second stage inlet at time t, the inlet performance index considering the change of the inlet angle under the outlet flow of the inlet when the aircraft is in the cruising state, and the inlet stability index considering the engine operating conditions and the changes of the inlet flow state.

[0034] Compared with the prior art, the present invention has at least the following beneficial effects:

[0035] 1. The comprehensive performance evaluation method of the air inlet in the optimization method of the present invention comprehensively considers the comprehensive performance of the air inlet in the cruising state, different engine operating conditions and external flow field conditions, and can be used to evaluate the comprehensive performance of the air inlet of the aircraft in the cruising state and when performing maneuvers, and the method is applicable to air inlets of different shapes.

[0036] 2. The present invention divides the optimization process of the planar embedded air inlet into a pre-optimization stage with the performance under the cruising state as the optimization target and a comprehensive optimization stage with the comprehensive performance under various working conditions as the optimization target, thereby reducing the dimension of the design space, saving the time required for optimization, and improving the optimization efficiency.

[0037] 3. The optimization method of the present invention takes into account the air intake principle of the plane embedded inlet, and aims at the negative impact of the low total pressure area at the inlet outlet caused by the lip suction vortex and the separation of the diffuser section on the aerodynamic performance of the inlet, and associates the inlet lip parameters with the diffuser section parameters to achieve comprehensive optimization that takes into account the coupled effects of the lip shape and the diffuser section shape on the inlet performance, thereby achieving more comprehensive optimization of the inlet performance and improving the optimization effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings are only for the purpose of illustrating particular embodiments and are not to be construed as limiting the invention.

[0039] Figure 1 It is a schematic structural diagram of the planar embedded air inlet of the present invention;

[0040] Figure 2 It is a schematic diagram of the centerline of the diffuser section of the planar embedded air inlet of the present invention;

[0041] Figure 3 is a schematic diagram of the lip side edge angle μ of the plane embedded air inlet of the present invention;

[0042] Figure 4 is a flow chart of the planar embedded air inlet optimization method of the present invention;

[0043] Figure 5 It is a schematic diagram of the total pressure distortion index DC60 solution principle of the post-processing module. DETAILED DESCRIPTION

[0044] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. In addition, the present invention can also be implemented in other ways different from those described herein, and therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0045] A specific embodiment of the present invention, as Figure 1-5 , discloses a planar embedded air inlet that takes into account comprehensive performance under multiple working conditions, comprising a lip 1, an inlet guide section 2 and a diffuser section 3; the inlet guide section 2 is arranged between the lip 1 and the diffuser section 3, and the connection between the inlet guide section 2 and the diffuser section 3 is an interface 1 5; an outlet section 6 is arranged at the place where the diffuser section 3 is connected to the inlet of the aircraft engine; an interface 2 4 is arranged at the place where the lip 1 is connected to the aircraft fuselage.

[0046] Furthermore, the ratio of the cross-sectional area of ​​the interface 2 4 to the cross-sectional area of ​​the outlet cross section 6 is the diffusion ratio Ad.

[0047] Further, see Figure 3 The angle between the side wall 7 of the inlet guide section 2 and the line 8 parallel to the axis of the inlet guide section 2 is the lip side edge angle μ.

[0048] Another specific embodiment of the present invention, as Figure 4 , discloses an optimization method for a planar embedded air intake duct considering comprehensive performance under multiple working conditions, and the specific steps are as follows:

[0049] S1. Establish a parametric surface model of the planar embedded air inlet.

[0050] Furthermore, the parameterized surface model includes first-stage design variables and second-stage design variables.

[0051] Furthermore, the first-stage design variables include a diffuser centerline shape control coefficient and a diffuser cross-sectional area distribution law control coefficient.

[0052] Among them, the control coefficient of the centerline shape of the diffuser section includes the fourth power coefficient n1, the cubic coefficient p1, and the quadratic coefficient q1 of the centerline shape of the diffuser section; the control coefficient of the cross-sectional area distribution law of the diffuser section includes the fourth power coefficient n2, the cubic coefficient p2, and the quadratic coefficient q2 of the cross-sectional area distribution law of the diffuser section.

[0053] Among them, the expression of the centerline shape of the diffuser section is:

[0054] Y=n1X 4 +p1X 3 +q1X 2

[0055] Wherein, Y represents the y-axis coordinate value of any point on the center line of the diffuser in the inlet body coordinate system; X represents the x-axis coordinate value of the corresponding point in the inlet body coordinate system.

[0056] Understandably, see Figure 2 The origin O of the coordinate system is located at the geometric center point of the intake duct interface 24, the x-axis is located in the intake duct symmetry plane, and its direction points to the intake duct outlet; the y-axis is located in the intake duct symmetry plane, perpendicular to the x-axis, and points to the top of the intake duct; the z-axis is perpendicular to the intake duct symmetry plane.

[0057] The expression of the cross-sectional area distribution law of the diffuser section is:

[0058] A=n2X 4 +p2X 3 +q2X 2

[0059] Wherein, A represents the cross-sectional area of ​​the diffuser corresponding to a plane passing through any point on the centerline of the diffuser and perpendicular to the centerline of the diffuser; X represents the x-axis coordinate value of the corresponding point in the inlet body coordinate system.

[0060] Furthermore, the second-stage design variables include the lip side angle μ and the diffusion ratio Ad.

[0061] S2. Initialize the parameters of the parametric surface model of the planar embedded air inlet.

[0062] Specifically, the initial diffuser centerline shape control coefficient is n 10 、p 10 ,q 10 , the control coefficient of the cross-sectional area distribution law of the diffuser section is n 20 、p 20 ,q 20 .

[0063] Set the target value of the total pressure distortion index of the inlet duct to be achieved in the first stage DC60 1 and total pressure recovery coefficient target value PR 1 . Enter the first stage of optimization.

[0064] S3. Let k = 0. When k = 0, it is the initial moment of the first stage.

[0065] S4. Based on the centerline shape control coefficient of the diffuser at the kth moment and the parameterized surface model of the plane embedded inlet in step S1, a first-stage plane embedded inlet at the kth moment is generated; meshing the plane embedded inlet surface model at the kth moment is performed to obtain a first-stage mesh at the kth moment;

[0066] S5. Import the first-stage grid at the kth moment in step S4 into the aerodynamic numerical simulation software, take the state of the external gas in the inlet duct in the cruise state of the aircraft as the first-stage boundary condition, perform aerodynamic numerical simulation on the inlet duct, and obtain the total pressure and dynamic pressure of the flow field at each point (i.e., each grid point) on the outlet cross section 6 of the inlet duct at the kth moment and the far-field free flow total pressure of the external flow field of the inlet duct;

[0067] S6. Input the flow field data (i.e., total pressure, dynamic pressure, and far-field free stream total pressure) obtained in S5 into the simulation data post-processing module to obtain the inlet total pressure distortion index DC60 at the kth moment k and total pressure recovery coefficient PR k .

[0068] The specific steps are:

[0069] S61. Based on the flow field data obtained in S5, the total pressure and dynamic pressure of each point on the outlet section 6 of the flow field at the kth moment are averaged to obtain the average total pressure p of the outlet section at the kth moment. av，k The average dynamic pressure q of the outlet section av，k .

[0070] S62. Figure 5 As shown, on the outlet section 6 at the kth moment, with the center of the outlet section 6 at the kth moment as the center of the circle, set the step length to r, and establish A sector area with a central angle of 60°.

[0071] S63. The average total pressure of the flow field in the fan-shaped area is solved, and the average total pressure in each fan-shaped area is compared to obtain the minimum average total pressure (p min，k ) 60° .

[0072] S64. Average total pressure p of the outlet section based on the kth moment av，k , average dynamic pressure at the outlet section q av，k and the minimum average total pressure (p min，k ) 60° Get the total pressure distortion index DC60 of the inlet at the kth moment k , the expression is:

[0073]

[0074] S65. Average total pressure p of the outlet section based on the kth moment av，k , obtain the total pressure recovery coefficient PR of the inlet duct at the kth moment k , the expression is:

[0075]

[0076] Among them, p t∞，k represents the far-field free stream total pressure of the inlet duct external flow field at the kth moment.

[0077] S7. Inlet total pressure distortion index DC60 based on the kth moment k and total pressure recovery coefficient PR k , determine whether the first-stage plane embedded air intake duct reaches the first-stage optimization target at the kth moment. If it reaches the first-stage optimization target, obtain the first-stage optimized air intake duct and enter step S8. If it does not reach the first-stage optimization target, obtain the first-stage air intake duct centerline expression coefficient n at the k+1th moment by the optimization algorithm. 1(k+1) 、p 1(k+1) ,q 1(k+1) , the coefficient n of the expression of the distribution law of the diffuser area 2(k+1) 、p 2(k+1) ,q 2(k+1) , let k=k+1, and return to step S4;

[0078] Furthermore, the optimization target of the first stage is DC60 k ≤DC60 1 , P.R. k ≥PR 1 ,DC60 1 Indicates the target value of the total pressure distortion index in the first stage; PR 1 Indicates the target value of the total pressure recovery coefficient in the first stage.

[0079] S8. Initialize the second stage parameters of the intake duct after the first stage optimization.

[0080] Specifically, initially, the inlet lip side angle is μ0, and the diffusion ratio is Ad0.

[0081] The present invention uses the lip side angle μ, a control parameter of the inlet lip shape, and the diffusion ratio Ad, a parameter for coupling the lip shape and the diffuser section shape, as design variables for the second-stage optimization, thereby effectively avoiding the degradation of the aerodynamic performance of the planar embedded inlet caused by the low total pressure area at the inlet outlet caused by the separation of the low total pressure area at the inlet outlet caused by the lip entrainment vortex of the designed planar embedded inlet and the diffuser section.

[0082] Obtain the second-stage optimization target and enter the second-stage optimization.

[0083] Preferably, the optimization objectives of the second stage include the performance index at the inlet design point, the inlet performance index considering the change of the inlet angle under the inlet outlet flow rate when the inlet is in the cruising state of the aircraft, and the inlet stability index considering the engine operating conditions and the change of the inlet flow state.

[0084] It can be understood that the design point refers to the external flow field conditions of the inlet duct in the cruising state and the flow conditions at the outlet of the inlet duct (at the outlet section 6); the performance index at the design point of the inlet duct refers to the performance index of the inlet duct when the inlet duct is working at the design point (cruising state).

[0085] Preferably, the performance index at the design point of the inlet duct includes a total pressure distortion index DP_DC60 at the design point and a total pressure recovery coefficient DP_PR at the design point.

[0086] Furthermore, the design point is (β0, α0), which means that the sideslip angle of the external flow of the inlet is β0 and the angle of attack is α0 under the designed cruising state.

[0087] Preferably, the inlet performance index considering the change of the inlet angle at the inlet outlet flow rate when the aircraft is in the cruising state includes the total pressure distortion index WM_DC60 considering the change of the inlet angle at the design point DPmassflow and total pressure recovery coefficient WM_PR DPmassflow

[0088] Furthermore, within the inlet flow angle range, the total pressure distortion index WM_DC60 considering the change of the inlet flow angle at the design point is DPmassflow and total pressure recovery coefficient WM_PR DPmassflow The expression is:

[0089]

[0090]

[0091] Where W DC60 (β, α) represents the weight of the total pressure distortion index DP_DC60(β, α) at ​​the design point under the working point (β, α) in the total pressure distortion index considering the change of the incoming flow angle; W PR(β, α) represents the weight of the total pressure recovery coefficient DP_PR(β, α) in the total pressure recovery coefficient at the working point (β, α); β represents the sideslip angle at the working point; α represents the angle of attack at the working point; β min and β max Respectively represent the lower and upper bounds of the sideslip angle of the working point; α min and α max They represent the lower and upper limits of the angle of attack of the working point respectively.

[0092] It will be appreciated that the operating point is the operating condition of the intake duct.

[0093] Since the air inlet works for a longer time at a working point close to the design point in the aircraft mission profile, the working point will deviate significantly from the design point only when it is subject to greater external disturbances and when climbing or diving at a large angle of attack. Therefore, the performance of the air inlet at a working point close to the design point has a greater impact on the flight performance of the aircraft's full mission process. The present invention assigns a higher weight to the air inlet performance at a working point near the design point, and a lower weight to the air inlet performance at a working point far from the design point, so that the weight decreases faster as the distance of the working point from the design point increases. This ensures that the optimized air inlet meets the mission requirements of the adapted aircraft.

[0094] Furthermore, using a quadratic function as the weight function, the expression is:

[0095]

[0096]

[0097] In the formula, l(β,α) represents the distance between the working point (β,α) and the design point (β0,α0), l max Indicates the farthest distance between the design point and the working point, b DC60 With b PR They represent the total pressure distortion index DC60 at the farthest working point and the total pressure recovery coefficient PR when considering the change of the incoming flow angle. DPmassflow and total pressure recovery coefficient WM_PR DPmassflow The weight of DC60 With b PR The value range is (0, 1).

[0098] Further DC60 With b PR Take 0.5 for both.

[0099] Further, l(β,α)=|(β0,α0)-(β,α)|;

[0100] Total pressure distortion index considering the change of the incoming flow angle at the flow rate at the design point of the present invention

[0101] WM_DC60 DPmassflow The total pressure recovery coefficient WM_PR considering the change of the flow angle at the design point flow rate DPmassflow It measures the global performance of the inlet at the design point flow rate over a specified range of sideslip angles and angles of attack. DPmassflow The smaller the global total pressure distortion, the better the inlet performance; WM_PR DPmassflow The larger the value, the greater the global total pressure recovery coefficient and the better the inlet performance.

[0102] The optimization method of the present invention measures the comprehensive aerodynamic performance of the inlet at different inlet angles (angle of attack and sideslip angle) by taking into account the inlet performance index of the change in the inlet angle at the inlet outlet flow rate when the inlet is in the cruising state of the aircraft, thereby ensuring that the selected inlet can have relatively good performance even when it deviates from the working state within a certain range.

[0103] Furthermore, the inlet stability index considering the engine operating conditions and the changes in the incoming flow state includes the total pressure distortion index change rate WM_DC60 Sensitivity and the total pressure recovery coefficient change rate WM_PR Sensitivity .

[0104] The present invention considers the total pressure distortion index of the flow angle change at the design point

[0105] WM_DC60 DPmassflow and total pressure recovery coefficient WM_PR DPmassflow Based on this, we further consider the total pressure distortion index change rate WM_DC60 Sensitivity and the total pressure recovery coefficient change rate WM_PR Sensitivity , which is used to measure the stability of the comprehensive aerodynamic performance of the air inlet under different working conditions of the engine and different external flow angles. Considering that the cruise missile adapted by the air inlet has not only the design point of the cruise stage, but also the design requirement of high-speed penetration at full throttle, when the engine switches from the cruise throttle to the full throttle in the acceleration stage, the air inlet faces the situation of working point switching. At this time, it is necessary to consider the stability of the air inlet operation to avoid excessive changes in performance parameters of the air inlet when the working point is switched, resulting in unstable engine operation and even surging. This ensures that the performance parameters of the selected air inlet change little when the engine working state is switched under different flow angles.

[0106] Furthermore, the total pressure distortion index change rate WM_DC60 Sensitivity and the total pressure recovery coefficient change rate WM_PR Sensitivity The expression is:

[0107]

[0108]

[0109] Among them, WM_DC60 DPmassflow with WM_PR DPmassflow They represent the total pressure distortion index and total pressure recovery coefficient of the inlet duct at the design flow rate considering the change of the incoming flow angle; WM_DC60 full thr ottle massflow with WM_PR full thr ottle massflow They respectively represent the total pressure distortion index and total pressure recovery coefficient considering the change of the incoming flow angle at the working point when the engine is at full throttle.

[0110] S9. Let t=0. When t=0, it is the initial moment of the second stage.

[0111] S10. Based on the control coefficient of the cross-sectional area distribution law of the diffuser section at the tth moment and the parameterized surface model of the planar embedded air inlet of step S1, a second-stage planar embedded air inlet at the tth moment is generated.

[0112] S11. Meshing the second-stage planar embedded air inlet at time t to obtain the second-stage mesh at time t;

[0113] S12. Import the second-stage grid at the tth moment in step S11 into the aerodynamic numerical simulation software; take the sideslip angle matrix, angle of attack matrix and outlet flow matrix with equal steps within the preset sideslip angle range, angle of attack range and inlet outlet flow range of the inlet external flow field; use the combination of the elements of the sideslip angle matrix, angle of attack matrix and outlet flow matrix as the second-stage boundary conditions, perform batch aerodynamic numerical simulation of the inlet, and obtain the total pressure at each point on the outlet section 6 of the inlet under different boundary conditions and the second-stage grid at the tth moment.

[0114] S13. The total pressure at each point on the outlet section 6 of the inlet duct under different boundary conditions and the second-stage grid at time t is input into the simulation data post-processing module, and the post-processing module outputs the performance index at the inlet duct design point of the second-stage inlet duct at time t: the total pressure distortion index DP_DC60 at the design point t and the total pressure recovery coefficient DP_PR at the design point t 2. Inlet performance index considering the change of inlet angle under the outlet flow of the inlet when the aircraft is in the cruising state: inlet global total pressure distortion index WM_DC60 DPmassflow，t , the inlet total pressure recovery coefficient WM_PR DPmassflow，t And the inlet stability index considering the engine operating conditions and the changes in the incoming flow state: the total pressure distortion index sensitivity WM_DC60Sensitivity，t and total pressure recovery coefficient sensitivity WM_PR Sensitivity，t .

[0115] S14. Performance index of the inlet design point of the second stage inlet based on the time t Total pressure distortion index DP_DC60 at the design point t and the total pressure recovery coefficient DP_PR at the design point t 2. Inlet performance index considering the change of inlet angle under the outlet flow of the inlet when the aircraft is in the cruising state: inlet global total pressure distortion index WM_DC60 DPmassflow，t , the inlet total pressure recovery coefficient WM_PR DPmassflow，t And the inlet stability index considering the engine operating conditions and the changes in the incoming flow state: the total pressure distortion index sensitivity WM_DC60 Sensitivity，t and total pressure recovery coefficient sensitivity WM_PR Sensitivity，t , determine whether the performance of the second-stage air intake duct at time t reaches the second-stage optimization target. If the second-stage optimization target is reached, obtain the optimized plane embedded air intake duct surface model and enter step S15. If the second-stage optimization target is not reached, obtain the lip side edge angle μ of the second-stage air intake duct at time t+1 by the optimization algorithm. (t+1) , expansion ratio Ad (t+1) Let t=t+1, and return to step S10;

[0116] S15. Output the optimized plane embedded air inlet surface model.

[0117] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A planar embedded air intake duct considering comprehensive performance under multiple working conditions, characterized in that: It includes a lip, an inlet guide section and a diffuser section; the inlet guide section is arranged between the lip and the diffuser section, and the connection between the inlet guide section and the diffuser section is interface 1; an outlet section is arranged at the connection between the diffuser section and the aircraft engine inlet; and interface 2 is arranged at the connection between the lip and the aircraft fuselage.

2. The planar embedded air intake according to claim 1, characterized in that: The ratio of the cross-sectional area of ​​interface 2 to the cross-sectional area of ​​the outlet cross section is the expansion ratio.

3. The planar embedded air intake according to claim 1, characterized in that: The angle between the side wall of the inlet guide section and the line parallel to the axis of the inlet guide section is the lip side angle.

4. A method for optimizing a planar embedded air intake duct considering comprehensive performance under multiple working conditions, wherein the planar embedded air intake duct of the aforementioned claims 1-3 is optimized, characterized in that: The specific steps are as follows: S1. Establish a parametric surface model of the plane embedded air inlet; S2. Initialize the parameters of the parametric surface model of the plane embedded air inlet; The parameterized surface model includes the first-stage model parameters and the second-stage model parameters; S3. Let k = 0. When k = 0, it is the initial moment of the first stage; S4. Based on the parameters of the parametric surface model of the plane embedded air inlet at the kth moment and the parametric surface model of the plane embedded air inlet in step S1, a first-stage plane embedded air inlet at the kth moment is generated; meshing the plane embedded air inlet surface model at the kth moment to obtain a first-stage mesh at the kth moment; S5. Based on the first-stage grid and the first-stage boundary conditions at the k-th moment in step S4, aerodynamic numerical simulation is performed on the air inlet to obtain the flow field data at each point on the outlet cross section of the air inlet at the k-th moment; S6. Input the flow field data obtained in S5 into the simulation data post-processing module to obtain the first stage evaluation index at the kth moment; S7. Based on the first-stage evaluation index, determine whether the first-stage embedded air intake duct at the kth moment has reached the first-stage optimization target. If it has reached the first-stage optimization target, obtain the first-stage optimized air intake duct and proceed to step S8. If it has not reached the first-stage optimization target, obtain the first-stage model parameters at the k+1th moment, set k=k+1, and return to step S4. S8. Initializing the second stage model parameters of the air intake after the first stage optimization; S9. Let t = 0. When t = 0, it is the initial time of the second stage; S10. Based on the second stage model parameters of the first stage optimized air intake at time t and the parameterized surface model of the plane embedded air intake in step S1, a second stage plane embedded air intake at time t is generated; S11. Meshing the second-stage planar embedded air inlet at time t to obtain the second-stage mesh at time t; S12. Based on the second-stage grid and the second-stage boundary conditions at the t-th time in step S11, a batch of aerodynamic numerical simulations are performed on the air intake duct to obtain the total pressure at each point on the outlet cross section of the air intake duct under the corresponding boundary conditions and the second-stage grid at the t-th time; S13. The total pressure at each point on the outlet cross section of the inlet duct under the second-stage grid corresponding to the boundary conditions and the t-th time is input into the simulation data post-processing module, and the post-processing module outputs the evaluation index of the second-stage inlet duct at the t-th time; S14. Based on the evaluation index of the second-stage air intake duct, determine whether the performance of the second-stage air intake duct at the t-th time reaches the second-stage optimization target. If the second-stage optimization target is reached, obtain the optimized plane embedded air intake duct surface model and proceed to step S15. If the second-stage optimization target is not reached, obtain the second-stage model parameters of the first-stage optimized air intake duct at the t+1th time, set t=t+1, and return to step S10. S15. Output the optimized plane embedded air inlet surface model.

5. The optimization method of the planar embedded air intake considering comprehensive performance under multiple working conditions according to claim 4 is characterized in that: The first stage model parameters include the diffuser centerline shape control coefficient and the diffuser cross-sectional area distribution law control coefficient; The second stage model parameters include lip side angle and diffusion ratio.

6. The optimization method of the planar embedded air intake considering comprehensive performance under multiple working conditions according to claim 5, characterized in that: The first-stage boundary condition in step S5 is the state of the external gas in the air inlet when the aircraft is in the cruising state.

7. The optimization method of the planar embedded air intake considering comprehensive performance under multiple working conditions according to claim 5, characterized in that: The process data in step S5 are the total pressure and dynamic pressure of the flow field at each point on the outlet cross section of the inlet duct at the kth moment and the far-field free stream total pressure of the flow field outside the inlet duct.

8. The optimization method of the planar embedded air intake considering comprehensive performance under multiple working conditions according to claim 5, characterized in that: The first stage evaluation index at the kth moment includes the inlet total pressure distortion index DC60 k and total pressure recovery coefficient PR k .

9. The optimization method of the planar embedded air intake considering comprehensive performance under multiple working conditions according to claim 5, characterized in that: The parameters of the parametric surface model of the plane embedded inlet include the coefficients of the centerline expression of the first stage inlet and the coefficients of the expression of the area distribution law of the diffuser section.

10. The optimization method of the planar embedded air intake considering comprehensive performance under multiple working conditions according to claim 5, characterized in that: The second-stage evaluation indicators include the performance indicators of the second-stage inlet at the inlet design point at time t, the inlet performance indicators considering the change of the inlet angle under the outlet flow of the inlet when the aircraft is in the cruising state, and the inlet stability indicators considering the engine operating conditions and the changes in the inlet flow state.

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