An Adaptive Waverider Design Method Based on Flight Speed ​​and Gas Model

Abstract

This application proposes an adaptive waverider design method. For hypersonic waverider design across a wide velocity range (Ma6–Ma25), an appropriate gas model is selected based on the different characteristics of applicable gas models in different velocity ranges. For the mid-velocity range (around Ma10–15) where the applicability of gas models is ambiguous, waveriders based on both a complete gas model and a realistic gas model are generated. A multi-component non-equilibrium PNS fast calculation method adapted to blunt-nosed body calculations is used to evaluate the lift-to-drag ratio performance, and the final waverider shape is determined by selecting the optimal model. Thus, an appropriate reference flow field gas model can be adaptively selected according to the velocity range, making the reference flow field closer to the actual flow field environment of the waverider in each velocity range. Theoretically, this method can obtain a waverider with superior performance compared to a single complete gas model.

Description

Technical Field

[0001] This application relates to the technical field of aerodynamic layout design of aircraft, and in particular to an adaptive waverider design method for flight speed and gas model. Background Technology

[0002] The waverider is an aerodynamic layout design concept for aircraft that meets the requirements of high lift-to-drag ratio, and it has received widespread attention and application in aircraft design. A waverider refers to an aircraft whose leading edge is closely aligned with a shock wave, completely confining the high-pressure zone behind the shock wave to the lower surface of the aircraft, thereby achieving extremely high lift and lift-to-drag ratio. To enable the aircraft to "ride the wave," the lower surface and leading edge of the waverider are obtained from a reference flow field through streamline tracing. This design ensures that the flow field of the aircraft at the design point is consistent with the reference flow field used in the design, thus guaranteeing accurate waveriding. It is conceivable that if the characteristics of the reference flow field used in the design differ from the characteristics of the actual flight flow field, even at the design point, the actual flight flow field cannot be consistent with the reference flow field, thus affecting the aircraft's waveriding performance. In flow field calculations, the gas model is one of the most important parameters affecting flow field characteristics.

[0003] When an aircraft flies at low speeds (Ma < 10), a complete gas model can accurately describe the thermodynamic properties of the gas. However, as the aircraft's speed increases, the complete gas model becomes inapplicable, and a realistic gas model becomes closer to the actual gas properties. Traditional waverider design uses a complete gas flow field as the reference flow field, without considering the applicability of the gas model to the real flight environment. When the aircraft's speed is very high, the difference between the realistic gas flow field and the complete gas flow field is significant, especially the shock wave separation distance, which is much smaller in the realistic gas flow field. This directly affects the leading edge shape of the generated waverider. Therefore, a mismatch between the reference flow field gas model used in waverider design and the gas model of the real flight environment may lead to the designed waverider not accurately riding the wave, resulting in a decrease in aerodynamic performance. Summary of the Invention

[0004] This application provides an adaptive waverider design method based on flight speed and gas model. The aim is to overcome the mismatch between the reference flow field gas model and flight speed in existing waverider design methods, and to provide a reference flow field simulation tool for multiple gas models, including complete gas, equilibrium gas, and five-component non-equilibrium gas. By designing a reasonable velocity range and gas model matching method, it ensures that waveriders designed for different velocity ranges in hypersonic flight can accurately ride the wave, achieving higher aerodynamic performance.

[0005] Firstly, a waverider design method is provided, including:

[0006] Based on the design Mach number, the gas model is determined from the full gas model and the real gas model;

[0007] Generate a reference flow field according to the gas model;

[0008] Generate a target waverider corresponding to the designed Mach number according to the reference flow field.

[0009] Combined with the first aspect, in some implementation manners of the first aspect, the determining the gas model from the perfect gas model and the real gas model according to the designed Mach number includes:

[0010] When 6 ≤ Ma ≤ 10, the gas model is the perfect gas model;

[0011] When 15 < Ma ≤ 25, the gas model is the real gas model;

[0012] When 10 < Ma ≤ 15, the gas model is the perfect gas model and the real gas model, where Ma is the designed Mach number.

[0013] Combined with the first aspect, in some implementation manners of the first aspect, the determining the gas model from the perfect gas model and the real gas model according to the designed Mach number includes:

[0014] Determine the gas model according to the waverider design gas model decision function Ma is the designed Mach number; c is an empirical parameter; where,

[0015] When Z < 5000, the gas model is the perfect gas model;

[0016] When Z > 10000, the gas model is the real gas model;

[0017] When 5000 < Z < 10000, the gas model is the perfect gas model and the real gas model.

[0018] Combined with the first aspect, in some implementation manners of the first aspect, in the case where the gas model is the perfect gas model and the real gas model, the generating the target waverider corresponding to the designed Mach number according to the reference flow field includes:

[0019] Generate a perfect gas model waverider according to the reference flow field corresponding to the perfect gas model;

[0020] Generate a real gas model waverider according to the reference flow field corresponding to the real gas model;

[0021] Select one with better aerodynamic performance from the perfect gas model waverider and the real gas model waverider as the target waverider.

[0022] In conjunction with the first aspect, in certain implementations of the first aspect, the aerodynamic performance preferably satisfies any one of the following:

[0023] The target waverider has a better lift-to-drag ratio at a specified angle of attack;

[0024] The target waverider has a better maximum lift-to-drag ratio.

[0025] In conjunction with the first aspect, in some implementations of the first aspect, the method further includes:

[0026] Obtain the inviscid flow field of a unit sphere corresponding to the design Mach number;

[0027] Based on the leading edge passivation size and flight angle of attack of the waverider, the inviscid flow field of the unit sphere is transformed to obtain the leading edge passivated spherical head flow field;

[0028] Based on the data of the flow field of the leading-edge passivated ball head on the leading-edge passivation fusion section, the PNS calculation method is used to obtain the PNS flow field of the waverider, wherein the leading-edge passivation fusion section extends beyond the subsonic region of the ball head;

[0029] By fusing the flow field data of the leading-edge blunted ball head and the PNS flow field, the complete flow field data of the waverider is obtained.

[0030] The aerodynamic performance of the waverider is evaluated based on the complete flow field data of the waverider.

[0031] Secondly, a method for evaluating the aerodynamic performance of a waverider is provided, including:

[0032] Obtain the inviscid flow field of a unit sphere corresponding to the design Mach number;

[0033] Based on the leading edge passivation size and flight angle of attack of the waverider, the inviscid flow field of the unit sphere is transformed to obtain the leading edge passivated spherical head flow field;

[0034] Based on the data of the flow field of the leading-edge passivated ball head on the leading-edge passivation fusion section, the PNS calculation method is used to obtain the PNS flow field of the waverider, wherein the leading-edge passivation fusion section extends beyond the subsonic region of the ball head;

[0035] By fusing the flow field data of the leading-edge blunted ball head and the PNS flow field, the complete flow field data of the waverider is obtained.

[0036] The aerodynamic performance of the waverider is evaluated based on the complete flow field data of the waverider.

[0037] In conjunction with the second aspect, in some implementations of the second aspect, the transformation of the inviscid flow field of the unit sphere based on the passivation size of the waverider's leading edge and the angle of attack includes:

[0038] The radius of the unit sphere inviscid flow field is increased by a factor of R / r to obtain an inviscid flow field with a radius of R. The radius of the unit sphere inviscid flow field is r, and the radius of the passivation dimension of the waverider leading edge is R.

[0039] Based on the flight angle of attack, the inviscid flow field with radius R is rotated by the same angle as the flight angle of attack.

[0040] In conjunction with the second aspect, in certain implementations of the second aspect, the method satisfies at least one of the following:

[0041] The angle between the vertical direction of the leading edge passivation fusion section and the airflow direction corresponding to the angle of attack is -15 to 15°.

[0042] The passivation radius of the leading edge of the waverider is 5 to 50 mm.

[0043] Thirdly, an electronic device is provided for performing the method as described in any of the implementations of the first to second aspects above.

[0044] Compared with the prior art, the solution provided in this application has at least the following beneficial technical effects:

[0045] (1) Break through the limitations of existing shock wave assembly methods that can only simulate a complete gas, overcome the limitations of classical wave rider design based on the assumption of a complete gas, develop the calculation capabilities of equilibrium gas, 5-component non-equilibrium gas and complete gas models, and provide a reference flow field that meets the requirements for accurate wave rider design in different velocity domains.

[0046] (2) Based on the design point velocity range, an appropriate gas model is adaptively selected to carry out wave rider design, automatically realize the accurate wave rider design of wave riders in different velocity ranges, and improve the design performance of wave riders with a wider velocity range in hypersonic speeds.

[0047] (3) When designing a waverider, reduce the amount of calculation required for aerodynamic performance evaluation by adjusting the leading edge passivation radius, and improve the efficiency of aerodynamic performance evaluation. Attached Figure Description

[0048] Figure 1 This is a schematic diagram showing the location of shock waves in a perfect gas and a real gas.

[0049] Figure 2 This is a schematic diagram of waverider generation;

[0050] Figure 3 The difference between the incoming flow state of real gas and the pure gas waverider. Detailed Implementation

[0051] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0052] The embodiment of this application provides a design method for an adaptive waverider with flight speed and gas model, including the following steps.

[0053] Step 101: Determine the gas model according to the given design Mach number. The gas model is used to generate a reference flow field in combination with the shock assembly method.

[0054] Step 102: Generate a reference flow field by the shock assembly method according to the gas model selected in step 101.

[0055] Step 103: Generate a waverider by streamline tracing according to the generated reference flow field.

[0056] In some embodiments, the gas model can be determined according to the value range of the design Mach number.

[0057] The Mach numbers from 6 to 25 are divided into three speed ranges, namely the low-speed range of 6 - 10, the medium-speed range of 10 - 15, and the high-speed range of 15 - 25. When 6 ≤ Ma ≤ 10, the perfect gas model is adopted; when 15 < Ma ≤ 25, the real gas model is adopted. When 10 < Ma ≤ 15, the perfect gas model and the real gas model can be used to generate reference flow fields respectively, and the waverider of the perfect gas model and the waverider of the real gas model are generated. Then, by evaluating the aerodynamic performance of the waverider, one of the waveriders of the perfect gas model and the waverider of the real gas model is selected as the final waverider shape.

[0058] In some other embodiments, the gas model can be determined according to the decision function of the waverider design gas model.

[0059] The decision function of the waverider design gas model can satisfy:

[0060]

[0061] where Ma is the design Mach number; c is an empirical parameter, usually taking values from 0.5 to 2, for example, taking the value of 1. In one embodiment, Z can be used to indicate the temperature after the shock wave.

[0062] When Z < 5000, the perfect gas model is adopted. When Z > 10000, the real gas model is adopted. When 5000 < Z < 10000, the perfect gas model and the real gas model can be used to generate reference flow fields respectively, and the waverider of the perfect gas model and the waverider of the real gas model are generated. Then, by evaluating the aerodynamic performance of the waverider, one of the waveriders of the perfect gas model and the waverider of the real gas model is selected as the final waverider shape.

[0063] In some embodiments, the shock wave assembly method can simulate both complete gases and real gases. In one embodiment, the shock wave assembly method can simulate the following gases: complete gases, equilibrium gases, and five-component non-equilibrium gases. Both equilibrium gases and five-component non-equilibrium gases are real gases; the five-component non-equilibrium gas can refer to a mixture of five components (N2, O2, N, O, NO) in air.

[0064] In some embodiments, the shock wave assembly method treats the external shock wave as the computational boundary. At the shock wave boundary, the Rankine-Hugoniot relation is used to satisfy the shock wave jumping relationship under the condition of a complete gas. Appropriate shock wave jumping relationships are established for equilibrium gas and five-component non-equilibrium gas based on different thermochemical assumptions. At the same time, the wavefront and waveback characteristic compatibility relationship of complete gas, equilibrium gas and five-component non-equilibrium gas is established to ensure the correct calculation of the shock wave boundary flow field parameters and avoid the occurrence of non-physical solutions.

[0065] In some embodiments, the shape of the reference flow field can be selected before generating the reference flow field using the shock wave assembly method. The shape of the reference flow field can be selected based on experience or waverider design requirements (e.g., aspect ratio requirements, volume ratio requirements, etc.). The shape of the reference flow field can be a single cone, a double cone, a single elliptical cone, a double elliptical cone, or other general three-dimensional shapes. In some embodiments, when the reference shape is a three-dimensional shape with a sharp head, such as a single cone or a double cone, a blunt-headed shape can be selected to blunt the sharp head of the three-dimensional shape.

[0066] In some embodiments, the leading edge of the waverider needs to be passivated to ensure it meets engineering requirements. This necessitates adjustments to the calculation of the waverider's gas properties.

[0067] This application also provides a method for evaluating the shape of a waverider.

[0068] 201. Obtain the inviscid flow field of a unit sphere corresponding to the design Mach number. This inviscid flow field of the unit sphere is used to generate the passivation flow field data of the waverider leading edge.

[0069] In some embodiments, to adapt to waverider designs with various design Mach numbers, the inviscid flow field of a unit sphere can be pre-calculated and stored every 1 Ma in the range of Ma6-Ma25. When the user needs to use the system, the inviscid flow field of the unit sphere at the corresponding design Mach number can be directly retrieved.

[0070] Depending on design requirements, the Mach number interval can be reduced when calculating the inviscid flow field on a unit sphere. For ease of subsequent application, the mesh size for the inviscid flow field on a unit sphere should be sufficiently dense to minimize interpolation errors during application.

[0071] 202. Based on the leading edge passivation size of the waverider and the flight angle of attack to be evaluated, the unit spherical inviscid flow field obtained in step 201 is transformed in size and coordinate. The transformed flow field is then extracted through the leading edge passivation fusion section to obtain the leading edge passivated spherical head flow field data of the waverider.

[0072] The passivation dimension of the waverider's leading edge corresponds to the radius of the inviscid flow field of a unit sphere. Assuming the radius of the inviscid flow field of a unit sphere corresponding to the design Mach number is *r*, and the radius of the passivation dimension of the waverider's leading edge is *R*, then increasing the radius of the inviscid flow field of the unit sphere by a factor of *R* / *r* yields an inviscid flow field with radius *R*. Combined with the angle of attack, this results in an inviscid flow field with a rotation radius of *R*. In some embodiments, the passivation radius of the waverider's leading edge is, for example, 5–50 mm; further, it is 10–30 mm.

[0073] The leading-edge passivation fusion section can be the intersection of the waverider's spherical head and the passivated leading edge. To ensure the waverider's shape meets engineering requirements, the leading-edge passivation region is smoothly connected by the spherical head and the passivated leading edge. In some embodiments, the angle between the vertical direction of the leading-edge passivation fusion section and the airflow direction corresponding to the angle of attack is -15° to 15°.

[0074] The leading-edge passivation fusion section needs to extend beyond the subsonic region of the ball head. If the leading-edge passivation fusion section does not extend beyond the subsonic region, the evaluation results may be inaccurate. Possible factors affecting this result include excessive angle of attack and an excessively small waverider ball head region.

[0075] 203. Based on the data of the flow field of the leading-edge blunted spherical head at the leading-edge blunted fusion section, the PNS flow field of the waverider is obtained using the PNS calculation method. The data of the flow field of the leading-edge blunted spherical head at the leading-edge blunted fusion section can be the initial cross-sectional flow field of the PNS flow field.

[0076] 204. By fusing the flow field data of the leading edge blunted ball head and the PNS flow field data, the complete flow field data of the waverider is obtained, and the aerodynamic performance of the waverider is evaluated.

[0077] Theoretically, after performing step 202, especially for scenarios with relatively large angles of attack, it is necessary to verify whether the leading-edge passivation fusion section extends beyond the subsonic region. Specifically, after obtaining the flow field parameters of the leading-edge passivation fusion section, it is possible to assess whether this section includes a subsonic region. If the leading-edge passivation fusion section does not extend beyond the subsonic region, the assessment result may be inaccurate. Possible factors affecting this result include excessively large angles of attack and excessively small ball-head regions.

[0078] In some embodiments, if the waverider evaluation does not meet the requirements, the shape of the reference flow field can be redesigned, the passivation size of the waverider leading edge can be updated, a suitable gas model can be selected, a new waverider shape can be redesigned, and steps 201 to 204 can be repeated until the waverider design meets the requirements.

[0079] As described above, in some embodiments, it is necessary to compare whether a full gas model waverider or a real gas model waverider is more suitable. After step 204, the aerodynamic performance of both the full gas model waverider and the real gas model waverider can be obtained through evaluation. By comparing the two aerodynamic performances, a suitable waverider shape can be selected. For example, a suitable waverider shape can be selected by comparing the lift-to-drag ratio of the waveriders.

[0080] In one embodiment, given a specified angle of attack, if the lift-to-drag ratio of the full gas model waverider is greater than that of the real gas model waverider, then the full gas model waverider is selected; if the lift-to-drag ratio of the real gas model waverider is greater than that of the full gas model waverider, then the real gas model waverider is selected.

[0081] In another embodiment, if the maximum lift-to-drag ratio of the full gas model waverider is greater than that of the real gas model waverider, then the full gas model waverider is selected; if the maximum lift-to-drag ratio of the real gas model waverider is greater than that of the full gas model waverider, then the real gas model waverider is selected. The aircraft can be used at the angle of attack corresponding to the maximum lift-to-drag ratio.

[0082] This application's embodiments overcome the limitations of the complete gas shock wave assembly method and establish a multi-gas model shock wave assembly method with complete gas, equilibrium gas, and 5-component non-equilibrium gas, providing a general three-dimensional shape reference flow field calculation tool for waverider design.

[0083] This application establishes a performance evaluation method based on rapid PNS spatial propulsion calculation with coupled spherical head inviscid flow field, realizing flow field calculation and performance evaluation of blunt-leading waveriders. To address the issue that the PNS rapid calculation method cannot calculate the subsonic region of the blunt-head body, the spherical head inviscid flow field at Ma6-Ma25 is pre-calculated. Through similarity principles and coordinate transformation methods, the spherical head inviscid flow field is transformed into a spherical head flow field of a given state, providing the initial field for the PNS rapid calculation method, which then completes the subsequent flow field calculations.

[0084] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims of the present invention.

Claims

1. A waverider design method, characterized in that, Comprising: Determine a gas model from a perfect gas model and a real gas model according to the design Mach number; Generate a reference flow field according to the gas model; Generate a target waverider corresponding to the design Mach number according to the reference flow field; The method further comprises: Obtain an inviscid flow field of a unit sphere corresponding to the design Mach number; Transform the inviscid flow field of the unit sphere according to the leading-edge blunting size of the waverider and the flight angle of attack to obtain a leading-edge blunted sphere-head flow field; Obtain the PNS flow field of the waverider by using the PNS calculation method according to the data of the leading-edge blunted sphere-head flow field on the leading-edge blunted fusion cross-section, and the leading-edge blunted fusion cross-section is outside the subsonic region of the sphere head; Fuse the data of the leading-edge blunted sphere-head flow field and the PNS flow field to obtain the complete flow field data of the waverider; Evaluate the aerodynamic performance of the waverider according to the complete flow field data of the waverider.

2. The method according to claim 1, characterized in that, The determining a gas model from a perfect gas model and a real gas model according to the design Mach number comprises: When 6 ≤ Ma ≤ 10, the gas model is a perfect gas model; When 15 < Ma ≤ 25, the gas model is a real gas model; When 10 < Ma ≤ 15, the gas model is a perfect gas model and a real gas model, where Ma is the design Mach number.

3. The method according to claim 1, characterized in that, The determining a gas model from a perfect gas model and a real gas model according to the design Mach number comprises: Decision function for designing a gas model based on waveriders The gas model is determined, where Ma is the design Mach number and c is an empirical parameter; where, When Z < 5000, the gas model is a perfect gas model; When Z > 10000, the gas model is a real gas model; When 5000 <Z <10000, the gas model is a complete gas model and a real gas model.

4. The method according to claim 2 or 3, characterized in that, In the case where the gas model is a perfect gas model and a real gas model, the generating a target waverider corresponding to the design Mach number according to the reference flow field comprises: Generate a perfect gas model waverider according to the reference flow field corresponding to the perfect gas model; Generate a real gas model waverider according to the reference flow field corresponding to the real gas model; Select one with better aerodynamic performance from the perfect gas model waverider and the real gas model waverider as the target waverider.

5. The method according to claim 4, characterized in that, The better aerodynamic performance satisfies any one of the following: The lift-to-drag ratio of the target waverider at a specified angle of attack is better; The maximum lift-to-drag ratio of the target waverider is better.

6. A method for evaluating the aerodynamic performance of a waverider, characterized in that, Comprising: Obtain an inviscid flow field of a unit sphere corresponding to the design Mach number; Transform the inviscid flow field of the unit sphere according to the leading-edge blunting size of the waverider and the flight angle of attack to obtain a leading-edge blunted sphere-head flow field; Obtain the PNS flow field of the waverider by using the PNS calculation method according to the data of the leading-edge blunted sphere-head flow field on the leading-edge blunted fusion cross-section, and the leading-edge blunted fusion cross-section is outside the subsonic region of the sphere head; Fuse the data of the leading-edge blunted sphere-head flow field and the PNS flow field to obtain the complete flow field data of the waverider; Evaluate the aerodynamic performance of the waverider according to the complete flow field data of the waverider.

7. The method according to claim 6, characterized in that, The transforming the inviscid flow field of the unit sphere according to the leading-edge blunting size of the waverider and the flight angle of attack comprises: The radius of the unit sphere inviscid flow field is increased by a factor of R / r to obtain an inviscid flow field with a radius of R. The radius of the unit sphere inviscid flow field is r, and the radius of the passivation dimension of the waverider leading edge is R. Based on the flight angle of attack, the inviscid flow field with radius R is rotated by the same angle as the flight angle of attack.

8. The method according to claim 6 or 7, characterized in that, The method satisfies at least one of the following: The angle between the vertical direction of the leading edge passivation fusion section and the airflow direction corresponding to the angle of attack is -15~15°. The passivation radius of the leading edge of the waverider is 5~50mm.

9. An electronic device, characterized in that, The electronic device is used to perform the method as described in any one of claims 1 to 8.

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