Design method for front-edge-passivated hypersonic-speed internal-contraction air inlet channel

Abstract

The invention discloses a design method for a front-edge-passivated hypersonic-speed internal contraction air inlet channel, and relates to the technical field of hypersonic-speed air inlet channels. The design method comprises the following steps that key design parameters are recognized and selected; parameterized modeling of the air inlet channel: drawing a shrinkage wall surface, segmenting the shrinkage wall surface by a shock wave cone, passivating the front edge of the air inlet channel, and drawing the solid shape of the air inlet channel; carrying out correlation analysis on design parameters; and optimization based on the proxy model. The method has the beneficial effects that parameterized design and multi-objective optimization of the air inlet duct structure can be realized, the performance of the air inlet duct can be effectively improved, the performance of the air inlet duct under different working conditions is improved, and the technical problems that the total pressure recovery coefficient is reduced and the shock wave shape is changed due to front edge passivation are solved.

Description

Technical Field

[0001] The invention relates to the technical field of hypersonic air inlets, and in particular to a design method for a hypersonic inward-retracting air inlet with a blunted leading edge. Background Art

[0002] The design of the inlet of a hypersonic vehicle is crucial to its aerodynamic performance and propulsion system. The existing hypersonic inward-contracting inlet adopts an inward-contracting structure, which has a smaller total pressure loss caused by shock waves and a higher compression efficiency than the traditional design method.

[0003] The existing inward-converging air intake design method designs a reference flow field according to certain design criteria, and then obtains the final air intake profile based on the reference flow field combined with streamline tracking technology.

[0004] The existing methods do not fully consider the impact of viscosity and leading edge passivation design. Leading edge passivation can effectively reduce the heat flux density, but it will reduce the total pressure recovery coefficient of the inlet and change the shock wave shape, deviating from the original design purpose.

[0005] In addition, existing methods do not consider the change in the angle of attack in the flight envelope. The weight of the aircraft changes during flight, causing the flight angle of attack to change, and the performance of the air inlet will change. The optimization of the entire hypersonic aircraft needs to take this change into account.

[0006] How to optimize the inlet design and take into account both aerodynamic performance and thermal protection has become a challenge in the design of hypersonic aircraft. Therefore, a design method for a hypersonic inward-retracted inlet with blunted leading edge is proposed to address the above problems. Summary of the invention

[0007] The purpose of the present invention is to provide a design method for a hypersonic inward-retracting inlet with blunted leading edge in order to solve the above-mentioned problems.

[0008] The present invention achieves the above-mentioned object through the following technical solutions, a method for designing a hypersonic inward-retracting inlet with blunted leading edge, comprising the following steps:

[0009] Step 1: Identification and selection of key design parameters;

[0010] Step 2: Parametric modeling of the air inlet: drawing the contraction wall, dividing the contraction wall with a shock cone, blunting the leading edge of the air inlet, and drawing the solid shape of the air inlet;

[0011] Step 3: Design parameter correlation analysis;

[0012] Step 4: Optimization based on proxy model.

[0013] Preferably, the guide line of the contraction wall is defined by six Bezier curve control points, wherein: the first control point is located at the leading edge of the air inlet; the second control point, the third control point, and the fourth control point are equidistantly distributed and are used to control the leading edge compression angle and adjust the curve shape; the fifth control point and the sixth control point are used to control the tangency of the air inlet curve with the isolation section and the outlet position and size of the air inlet.

[0014] Preferably, the bottom radius of the shock cone is set to be equal to the height of the inlet duct, and the height of the cone is used as an adjustable variable to control the contraction ratio in the inlet duct.

[0015] Preferably, the step of passivating the leading edge of the air inlet includes: drawing an extended elliptical section on the outside of the contraction wall surface; projecting the leading edge of the segmented contraction wall surface onto the outer contraction wall surface to obtain an outer reference curve with a rounded corner sweep; sweeping along the leading edge of the air inlet and the outer reference curve to form a passivation of the leading edge of the air inlet tangent to the inner wall surface.

[0016] Preferably, the identification and selection of key design parameters include: leading edge compression angle δ; position ratio h1 and h2 of inlet guide line control points; inlet total length scaling SL and outlet height scaling SH; and height scaling SC of the cone formed by the leading edge shock wave of the reference flow field.

[0017] Preferably, the design parameter correlation analysis step further includes: fitting the relationship between the inlet duct reference length Li and the outlet reference height Ho and the inlet height Hi according to the leading edge compression angle δ; fitting the shock wave cone length LC according to the relationship between the oblique shock wave angle and the fold angle; using a linear fitting method to derive the starting boundary equations of h1 and h2 to optimize the design parameter value range.

[0018] Preferably, the optimization steps based on the proxy model include: sampling design variables; analyzing sample solutions using aerodynamic analysis methods; establishing proxy models of total pressure recovery coefficient, flow coefficient, compression ratio and lift-to-drag ratio; evaluating the accuracy of the proxy model; increasing sample points to improve the accuracy of the proxy model; and iteratively updating the proxy model until the accuracy of the proxy model meets the requirements.

[0019] Preferably, after the optimization calculation is completed, a trade-off analysis is performed on the total pressure recovery coefficient, compression ratio, mass flow rate, and lift-to-drag ratio of each intake duct scheme based on the optimal solution set to determine a reasonable intake duct design scheme.

[0020] The beneficial effects of the present invention are: it can realize the parametric design and multi-objective optimization of the inlet structure, can effectively improve the performance of the inlet, enhance the performance of the inlet under different working conditions, and solve the technical problem that the leading edge passivation will lead to a decrease in the total pressure recovery coefficient and a change in the shock wave shape. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0022] Figure 1 , is a schematic diagram of the shrinkage wall in the present invention.

[0023] Figure 2 , is a schematic diagram of shock cone segmentation in the present invention.

[0024] Figure 3 , is a schematic diagram of the inlet leading edge passivation in the present invention.

[0025] Figure 4 , is a schematic diagram of the physical appearance of the air inlet duct in the present invention.

[0026] Figure 5 , is a schematic diagram of the guide line control point in the present invention.

[0027] Figure 6 , is an enlarged schematic diagram of the inlet leading edge passivation in the present invention.

[0028] Figure 7 , is a schematic diagram of the entire hypersonic aircraft of the present invention.

[0029] In the figure: 1. Contraction wall; 2. Guide line; 3. Shock cone; 4. Inlet leading edge blunting; 5. Inlet entity; 6. First control point; 7. Second control point; 8. Third control point; 9. Fourth control point; 10. Fifth control point; 11. Sixth control point; 12. Outer reference curve. DETAILED DESCRIPTION

[0030] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0032] In the description of the present invention, it is necessary to understand that the orientations or positional relationships indicated by the terms "upper", "lower", "top", "bottom", "inside", "outside", etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0033] See also Figure 1-7 As shown, a method for designing a hypersonic inward-retracted inlet with a blunted leading edge comprises the following steps:

[0034] Step 1: Identification and selection of key design parameters;

[0035] Step 2: parametric modeling of the air inlet: drawing the contraction wall 1, dividing the contraction wall 1 by the shock cone 3, blunting the leading edge of the air inlet 4, and drawing the shape of the air inlet entity 5;

[0036] Step 3: Design parameter correlation analysis;

[0037] Step 4: Optimization based on proxy model.

[0038] Furthermore, the guide line 2 of the contraction wall 1 is defined by six Bezier curve control points, wherein: the first control point 6 is located at the leading edge of the air inlet; the second control point 7, the third control point 8, and the fourth control point 9 are equidistantly distributed and used to control the leading edge compression angle and adjust the curve shape; the fifth control point 10 and the sixth control point 11 are used to control the tangency of the air inlet curve with the isolation section and the outlet position and size of the air inlet.

[0039] Furthermore, the bottom radius of the shock cone 3 is set to be equal to the height of the inlet duct, and the height of the cone is used as an adjustable variable to control the contraction ratio in the inlet duct.

[0040] Furthermore, the step of passivating the leading edge of the air inlet 4 includes: drawing an extended elliptical section on the outside of the contraction wall 1; projecting the leading edge of the segmented contraction wall 1 onto the outer contraction wall to obtain a rounded swept outer reference curve 12; sweeping along the leading edge of the air inlet and the outer reference curve to form a passivation of the leading edge of the air inlet 4 tangent to the inner wall.

[0041] Furthermore, the identification and selection of key design parameters include: leading edge compression angle δ; position ratio h1 and h2 of inlet guide line control points; inlet total length scaling S L and export height scale S H ; The height scaling S of the cone formed by the shock wave at the leading edge of the reference flow field C .

[0042] Furthermore, the design parameter correlation analysis step further includes: fitting the inlet duct reference length L according to the leading edge compression angle δ i The exit reference height H o And entrance height H i According to the relationship between the oblique shock wave angle and the fold angle, the shock wave cone length L is fitted. C ; The linear fitting method is used to derive the starting boundary equations of h1 and h2 and optimize the value range of design parameters.

[0043] Furthermore, the optimization steps based on the proxy model include: sampling design variables; analyzing the sample schemes using aerodynamic analysis methods; establishing proxy models of total pressure recovery coefficient, flow coefficient, compression ratio and lift-to-drag ratio; evaluating the accuracy of the proxy model; increasing sample points to improve the accuracy of the proxy model; and iteratively updating the proxy model until the accuracy of the proxy model meets the requirements.

[0044] Furthermore, after the optimization calculation is completed, a trade-off analysis is performed on the total pressure recovery coefficient, compression ratio, mass flow rate, and lift-to-drag ratio of each intake duct scheme based on the optimal solution set to determine a reasonable intake duct design scheme. Specific embodiments

[0046] A method for designing a hypersonic inward-retracting inlet with blunted leading edge comprises the following steps:

[0047] 1. Identification and selection of key parameters

[0048] In the process of inlet design, the key geometric parameters that affect the inlet performance must first be identified. These key parameters include the leading edge compression angle δ, the position ratio of the inlet guide line control points h1 and h2, the inlet total length scaling SL, the outlet height scaling SH, and the height scaling SC of the shock wave forming cone at the leading edge of the reference flow field. Selecting these parameters as design variables can effectively control the inlet geometry with a small number of parameters and provide sufficient design space for the subsequent optimization process.

[0049] 2. Parametric modeling of the air intake duct

[0050] The parametric modeling of the inlet includes four sub-steps: drawing the contraction wall, dividing the contraction wall with a shock cone, blunting the leading edge of the inlet, and drawing the solid shape of the inlet.

[0051] 2.1 Shrinkage wall drawing

[0052] In the process of parametric modeling of the air inlet, the contraction wall of the air inlet is first drawn. The inlet and outlet cross-sections are both elliptical, and their major and minor semi-axes are preliminarily determined according to the required thrust and the leading edge compression angle δ. The specific steps are as follows:

[0053] Define the inlet and outlet cross-sections: According to design requirements, set the major semi-axis ai and minor semi-axis bi of the inlet ellipse.

[0054] Draw guide lines: Use six Bezier curve control points to define the guide lines of the intake duct contraction wall. The first control point is located at the leading edge of the intake duct. The second, third, and fourth control points are equidistantly distributed to control the leading edge compression angle and adjust the curve shape. The fifth and sixth control points are used to control the tangency of the intake duct curve and the isolation section and the position and size of the intake duct outlet. According to the set section and guide line, the three-dimensional shape of the contraction wall is generated by the Bezier curve.

[0055] 2.2 Shock wave cone divides the contraction wall

[0056] After the contraction wall is drawn, a shock cone is constructed based on the leading edge shock wave shape of the reference flow field and used to segment the contraction wall to generate a three-dimensional inward contraction inlet wall. The bottom radius of the shock cone is set to be equal to the inlet inlet height, and the height of the cone is used as an adjustable variable SL to control the contraction ratio in the inlet. The contraction wall is segmented by the shock cone to form an inward contraction structure. By adjusting the height of the shock cone, the contraction ratio in the inlet is controlled to optimize the start-up performance of the inlet.

[0057] 2.3 Inlet leading edge passivation

[0058] In order to reduce the heat flux density at the leading edge of the inlet duct, the leading edge of the inlet duct needs to be passivated.

[0059] The specific steps are as follows:

[0060] Draw an extended elliptical section: Draw an extended elliptical section outside the contraction wall and increase the fillet radius of the leading edge;

[0061] Projection fillet reference curve: Project the leading edge of the segmented contraction wall onto the outer contraction wall to obtain the outer reference curve of the fillet sweep;

[0062] Forming a rounded leading edge: Sweep along the leading edge of the inlet and the outer reference curve to form a rounded leading edge blunting that is tangent to the inner wall surface.

[0063] 2.4 Drawing of the solid shape of the air intake

[0064] After completing the leading edge passivation, it is necessary to draw the solid shape of the air inlet for subsequent computational fluid dynamics simulation. The specific steps are as follows: join the various surfaces, join the inner wall of the air inlet with the outer shell to form a closed solid model suitable for CFD simulation calculation.

[0065] 3. Design parameter correlation analysis

[0066] After the parametric modeling is completed, it is necessary to analyze the correlation between the design parameters to determine the value range and optimization direction of each parameter; fit the relationship between the leading edge compression angle and the reference length: according to the leading edge compression angle δ, fit the relationship between the inlet duct reference length Li and the outlet reference height Ho and the inlet height Hi; fit the relationship between the shock cone length and the oblique shock wave angle: according to the relationship between the oblique shock wave angle and the fold angle, fit the shock cone length LC; derive the starting boundary equation: use the linear fitting method to derive the starting boundary equation of the inlet guide line control point positions h1 and h2 to optimize the value range of the design parameters and ensure that the inlet has good starting performance under different working conditions.

[0067] 4. Optimization based on proxy model

[0068] In order to improve the efficiency and optimization accuracy of the air intake design, the present invention adopts an optimization method based on a proxy model, and the specific steps are as follows:

[0069] 4.1 Design variable sampling: The Latin hypercube method is used to sample the design variables in the design space to obtain multiple sample design schemes.

[0070] 4.2 Aerodynamic analysis: Analyze the sample solutions and obtain the performance indicators of each sample solution, including total pressure recovery coefficient, flow coefficient, pressure increase ratio and lift-to-drag ratio;

[0071] 4.3 Establishing proxy models: Based on sample data, establish proxy models of total pressure recovery coefficient, flow coefficient, pressure increase ratio and lift-to-drag ratio;

[0072] 4.4 Add new sample points to improve the accuracy of the proxy model. Perform aerodynamic analysis on the newly added sample point scheme, add the analysis results to the sample data set, and update the proxy model;

[0073] 4.5 Iterative optimization: Repeat the process of adding sample points and updating the proxy model until the accuracy of the proxy model meets the requirements;

[0074] 4.6 Multi-objective optimization: A multi-objective genetic algorithm with non-dominated sorting is used to perform multi-objective optimization based on the agent model to obtain the optimal solution set of the total pressure recovery coefficient, flow coefficient, compression ratio and lift-to-drag ratio; based on the optimal solution set, a trade-off analysis is performed on the performance parameters of each inlet duct scheme to determine a reasonable inlet duct design scheme.

[0075] The benefit of the invention lies in that it can realize the parametric design and multi-objective optimization of the intake duct structure, can effectively improve the performance of the intake duct, and enhance the performance of the intake duct under different working conditions.

[0076] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0077] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A design method for a hypersonic inward-retracting inlet with blunted leading edge, characterized in that: The following steps are involved: Step 1: Identification and selection of key design parameters; Step 2, parametric modeling of the air inlet: drawing the contraction wall surface (1), dividing the contraction wall surface (1) with a shock cone (3), blunting the leading edge of the air inlet (4), and drawing the shape of the air inlet entity (5); Step 3: Design parameter correlation analysis; Step 4: Optimization based on proxy model.

2. The method for designing a hypersonic inward-retracting inlet with blunted leading edge according to claim 1, characterized in that: The guide line (2) of the contraction wall (1) is defined by six Bezier curve control points, wherein: the first control point (6) is located at the leading edge of the air inlet; the second control point (7), the third control point (8), and the fourth control point (9) are equidistantly distributed and used to control the leading edge compression angle and adjust the curve shape; the fifth control point (10) and the sixth control point (11) are used to control the tangency of the air inlet curve with the isolation section and the outlet position and size of the air inlet.

3. The method for designing a hypersonic inward-retracting inlet with blunted leading edge according to claim 1, characterized in that: The bottom radius of the shock cone (3) is set to be equal to the height of the air inlet entrance, and the height of the cone is used as an adjustable variable to control the contraction ratio in the air inlet.

4. The method for designing a hypersonic inward-retracting inlet with blunted leading edge according to claim 1, characterized in that: The step of blunting the leading edge of the air inlet (4) comprises: drawing an extended elliptical section on the outside of the contraction wall (1); projecting the leading edge of the segmented contraction wall (1) onto the outer contraction wall to obtain an outer reference curve (12) with rounded corners; and sweeping along the leading edge of the air inlet and the outer reference curve to form a blunting of the leading edge of the air inlet (4) tangent to the inner wall.

5. The method for designing a hypersonic inward-retracting inlet with blunted leading edge according to claim 1, characterized in that: The identification and selection of key design parameters include: leading edge compression angle δ; position ratio h1 and h2 of inlet guide line control points; inlet total length scaling S L and export height scale S H ; The height scaling S of the cone formed by the shock wave at the leading edge of the reference flow field C .

6. The method for designing a hypersonic inward-retracting inlet with blunted leading edge according to claim 1, characterized in that: The design parameter correlation analysis step further includes: fitting the inlet duct reference length L according to the leading edge compression angle δ i The exit reference height H o And entrance height H i According to the relationship between the oblique shock wave angle and the fold angle, the shock wave cone length L is fitted. C ; The linear fitting method is used to derive the starting boundary equations of h1 and h2 and optimize the value range of design parameters.

7. The method for designing a hypersonic inward-retracting inlet with blunted leading edge according to claim 1, characterized in that: The optimization steps based on the proxy model include: sampling design variables; analyzing sample solutions using aerodynamic analysis methods; establishing proxy models of total pressure recovery coefficient, flow coefficient, pressure ratio and lift-to-drag ratio; evaluating the accuracy of the proxy model; increasing sample points to improve the accuracy of the proxy model; and iteratively updating the proxy model until the accuracy of the proxy model meets the requirements.

8. The method for designing a hypersonic inward-retracting inlet with blunted leading edge according to claim 7, characterized in that: After the optimization calculation is completed, a trade-off analysis is performed on the total pressure recovery coefficient, compression ratio, mass flow rate, and lift-to-drag ratio of each intake duct scheme based on the optimal solution set to determine a reasonable intake duct design scheme.

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