High-density flow front fuselage shell for abdomen air inlet aircraft and front fuselage

Abstract

The invention relates to a high-density flow front fuselage shell and a front fuselage for an abdomen air inlet aircraft, and the high-density flow front fuselage shell comprises a front fuselage back structure and a front fuselage abdomen structure; the front end of the front fuselage back structure and the front end of the front fuselage abdomen structure are connected with each other in the longitudinal direction of the high-density flow front fuselage shell; in the transverse direction of the high-density flow front fuselage shell, the left and right ends of the front fuselage back structure are connected with the left and right ends of the front fuselage abdomen structure respectively; in the direction from the front end to the rear end of the front fuselage back structure, the back exterior molded surface of the front fuselage back structure is a convex curved surface protruding in the normal direction; in the direction from the front end to the rear end of the front fuselage belly structure, the belly outer molded surface of the front fuselage belly structure comprises a pre-compression molded surface and a dense flow enhanced surface which are connected in sequence; and a transition structure is arranged at the connecting position of the pre-compression molded surface and the dense flow enhanced surface. The compression efficiency of incoming air flow is high, the flow loss is small, and the aerodynamic resistance is low.

Description

Technical Field

[0001] The invention relates to the field of aerospace, and in particular to a high-density flow front fuselage shell and a front fuselage for a belly-intake aircraft. Background Art

[0002] For practical high-speed aircraft, it is necessary to comprehensively consider multiple performance indicators such as internal loading space, external geometric envelope, integrated aerodynamic characteristics, air capture efficiency, etc. The abdominal air intake layout scheme is the easiest to meet the above requirements at the same time.

[0003] The front fuselage is the most critical component of the aircraft with a belly air intake layout. In engineering practice, on the one hand, the front fuselage is required to have excellent aerodynamic performance, such as high lift and low drag; on the other hand, the front fuselage is required to have good loading capacity and structural performance, such as large space volume, easy processing, easy heat protection, etc. For high-speed aircraft, it is often necessary to integrate the front fuselage and the air intake into an integrated design, which puts higher requirements on the front fuselage. In addition to meeting the basic aerodynamic performance requirements and loading and structural performance requirements, it should also ensure that the air intake can capture enough high-quality incoming flow. Furthermore, since the air intake of high-speed aircraft often has problems with starting and not starting, when the air intake does not start, it will seriously threaten flight safety, and the design of the front fuselage is also directly related to the starting ability of the air intake.

[0004] At present, the research and engineering practice on the design of the front fuselage of the belly-intake high-speed aircraft are relatively common, as follows: The United States' X43A and X51A hypersonic aircraft are representative belly-intake high-speed aircraft. Both adopt an integrated solution of the front fuselage of the lifting body and the two-dimensional air inlet (Reference: Wang Zhenguo, Liang Jianhan, Fan Xiaoqiang, et al. Integrated solution of air-breathing high-speed aircraft: review and prospect [J]. Acta Aerodynamica Sinica, 2023, 41(8):13-25.). Among them, the front fuselage of the X43A provides three-stage wedge compression (reference: Meng Yupeng, Yang Hui, Man Yanjin. Development of integrated design technology for hypersonic inlet aircraft [J]. Gas Physics, 2021, 6(4): 66-83.), while the compression of the gas by the front fuselage of the X51A is achieved by two-stage plane compression, and there is an overflow window between the inlet and the front fuselage (reference: HANK J. The X-51A scramjet engine flight demonstration program; BORG M P. Effect of freestream noise on roughnessinduced transition for the X-51A forebody). In addition, the difference between the X43A and X51A is also reflected in the leading edge profile: the leading edge of the X43A is a straight line, and the leading edge of the X51A is a quasi-elliptical curve. Due to the single compression direction, the dense flow at the inlet entrance of the X43A and X51A is not high.

[0005] In addition, the HSSW aircraft represents another type of high-speed aircraft with ventral air intake. In order to increase the loading space, this type of aircraft generally adopts an axisymmetric or quasi-axisymmetric convex forebody, which results in a low density flow at the inlet entrance. In order to compensate for this defect, the HSSW arranges a three-dimensional inward-turning air intake on the ventral surface (reference: Wu Hui, Niu Wen. The United States actively develops hypersonic weapons [J]. Cruise Missile, 2014 (8): 4.). This air intake effectively increases the density flow through multi-directional three-dimensional compression, but there are problems such as heavy air intake structure and difficult heat protection of sharp leading edge. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a high-density flow front fuselage shell and a front fuselage for a belly-intake aircraft.

[0007] To achieve the above-mentioned object of the invention, the present invention provides a high-density flow front fuselage shell for a belly-intake aircraft, comprising: a front fuselage back structure and a front fuselage belly structure; Along the longitudinal direction of the high-density flow front fuselage shell, the front end of the front fuselage back structure and the front end of the front fuselage belly structure are connected to each other; Along the transverse direction of the high-density flow front fuselage shell, the left and right ends of the front fuselage back structure are respectively connected to the left and right ends of the front fuselage belly structure; Along the direction from the front end to the rear end of the front fuselage back structure, the back outer surface of the front fuselage back structure is an outward convex curved surface that bulges along the normal direction; Along the direction from the front end to the rear end of the front fuselage belly structure, the belly outer profile of the front fuselage belly structure includes: a pre-compression profile and a dense flow enhancement profile connected in sequence; A transition structure is arranged at a position where the pre-compression profile and the dense flow enhancement profile are connected.

[0008] According to one aspect of the present invention, along the longitudinal direction of the high-density flow front fuselage shell, the back outer surface and the belly outer surface are respectively axisymmetric surfaces.

[0009] According to one aspect of the present invention, the dense flow enhancement surface comprises: a forward compression surface portion, a lateral compression surface portion, and a straightening surface portion; Along the transverse direction of the high-density flow front fuselage shell, the lateral compression surface portion is respectively arranged at the left and right ends of the forward compression surface portion, and the straightening surface portion is arranged at one end of the lateral compression surface portion away from the forward compression surface portion; Along the direction from the front end to the rear end of the front fuselage belly structure, the position where the lateral compression surface portion is connected to the fairing surface portion is at least partially protruding in the direction away from the front fuselage back structure in the normal direction.

[0010] According to one aspect of the present invention, along the direction from the front end to the rear end of the front fuselage belly structure, the protruding height of the position where the lateral compression surface portion is connected to the fairing surface portion along the direction normal away from the front fuselage back structure is variable; and the front end width of the lateral compression surface portion is greater than the rear end width thereof, and the front end width of the fairing surface portion is less than the rear end width thereof.

[0011] According to one aspect of the present invention, along the transverse direction of the high-density flow front fuselage shell, the lateral compression surface portion is provided with mutually connected concave structures and convex structures; wherein the concave structure is arranged adjacent to the forward compression surface portion; and the convex structure is arranged adjacent to the straightening surface portion.

[0012] According to one aspect of the present invention, the back profile is generated by using one of the CST modeling method, PARSEC method, B-spline curve method, Hicks-Henne basis function method, FFD free deformation method, and streamline tracing method; The abdominal outer profile is generated by using one of the following methods: CST modeling method, PARSEC method, B-spline curve method, Hicks-Henne basis function method, FFD free deformation method, and streamline tracing method; According to one aspect of the present invention, the pre-compression profile is a combination of one or more of a flat surface, a convex curved surface, and a concave curved surface; The projection of the pre-compression profile is one of a semi-ellipse, a semi-ellipse-like shape, a triangle, a triangle-like shape, a square, and a square-like shape.

[0013] According to one aspect of the present invention, the back outer profile and the abdomen outer profile are obtained based on the following steps, which include: Constructing a two-dimensional cross-sectional shape of the corresponding outer profile, wherein the basic outer shape features of the corresponding outer profile are described based on a first-type function, and the basic outer shape features are locally corrected by a first shape function to obtain the two-dimensional cross-sectional shape; Constructing a variation rule of the two-dimensional cross-sectional shape along the flow direction, wherein the variation rule is constructed based on a second shape function and a second type function; Based on the two-dimensional cross-sectional shape and the variation rule, a plurality of external profile sections with different shapes are sequentially discretized in the three-dimensional space along the flow direction, and the aerodynamic configuration of the corresponding external profile is fitted based on the external profile sections.

[0014] According to one aspect of the present invention, the two-dimensional cross-sectional shape is expressed as: ; in, is the first shape function, is a first-class function, , , They are , , The dimensionless parameter of direction, is the intermediate function, is the intermediate function; The variation rule is expressed as: ; in, It is the longitudinal length of the high-density flow front fuselage shell from the front end to the rear end, is the second shape function, is a second-class function, is the first shape function, is a first-class function, is the section height, is the cross-section width, , , is an intermediate function.

[0015] To achieve the above-mentioned purpose, the present invention provides a front fuselage, including: a front fuselage shell and airborne equipment; the front fuselage shell is the aforementioned high-density flow front fuselage shell for belly-intake aircraft.

[0016] According to one solution of the present invention, the high-density flow front fuselage shell of the present invention can increase the dense flow at the inlet entrance on the one hand, and on the other hand will not bring about excessive structural, volumetric, resistance, flow loss and other costs, effectively ensuring the performance of the aircraft using the present invention while fully reducing its processing difficulty.

[0017] According to one solution of the present invention, the present invention realizes a high-density flow of gas at the inlet of the air intake duct, and after the density flow is improved, the three-dimensional inward-turning air intake duct can be mismatched.

[0018] According to one solution of the present invention, the configuration of the high-density flow front fuselage shell of the present invention has high compression efficiency for incoming air flow, small flow loss and low aerodynamic resistance.

[0019] According to one solution of the present invention, the curved surface used to enhance the dense flow in the high-density flow front fuselage shell of the present invention can be integrated with the front fuselage body, and the aerodynamic surface is round and smooth without sharp corners, which has advantages in structural realization, loading efficiency, weight and heat protection.

[0020] According to one solution of the present invention, the outer surface of the abdomen of the present invention performs the first compression on the gas by the pre-compression type surface, and the dense flow enhancement type surface performs the second compression on the gas after the first compression; wherein the secondary compression process of the gas is based on two dimensions, firstly, under the lateral compression of the lateral compression surface part, the gas is collected in the middle, and secondly, the positive compression surface part in the middle also realizes the three-dimensional compression of the gas. Therefore, the high-density flow of the gas at the inlet of the air intake is fully realized through the above two compressions.

[0021] According to one solution of the present invention, the rectifying surface portion provided in the abdominal outer profile of the present invention can be used for smooth connection between the lateral compression surface portion and the back outer profile, thereby effectively reducing aerodynamic resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a perspective view schematically showing a high-density flow front fuselage shell according to an embodiment of the present invention; Figure 2 is a front view schematically showing a high-density flow front fuselage shell according to an embodiment of the present invention; Figure 3 is a side view schematically showing a high-density flow front fuselage shell according to an embodiment of the present invention; Figure 4 Schematically shows a projection shape diagram of a pre-compression profile according to an embodiment of the present invention; Figure 5 is a diagram schematically showing a projection shape of a pre-compression profile according to another embodiment of the present invention; Figure 6is a diagram schematically showing a projection shape of a pre-compression profile according to another embodiment of the present invention; Figure 7 is a structural diagram schematically showing a plurality of symmetrical parts of the outer profile cross section with different shapes discretized based on the two-dimensional cross-sectional shape and the variation rule in the abdominal outer profile according to an embodiment of the present invention; Figure 8 is a three-dimensional diagram schematically showing the outer profile of a high-density flow front fuselage shell fitted according to an embodiment of the present invention; Fig. 9 is a bottom view schematically showing the outer profile of a high-density flow front fuselage shell fitted according to an embodiment of the present invention; Fig.10 is an enlarged view schematically showing a dense flow enhancement profile fitted according to an embodiment of the present invention; Fig.11 It is a bottom view schematically showing a dense flow enhancement profile fitted according to an embodiment of the present invention. DETAILED DESCRIPTION

[0023] 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 are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] When describing the embodiments of the present invention, the orientation or positional relationship expressed by the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or positional relationship shown in the relevant drawings and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0025] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the embodiments of the present invention are not therefore limited to the following embodiments.

[0026] Combination Figure 1 , Figure 2 and Figure 3As shown, according to an embodiment of the present invention, a high-density flow front fuselage shell for a belly-intake aircraft of the present invention comprises: a front fuselage back structure 11 and a front fuselage belly structure 12; in this embodiment, along the longitudinal direction (i.e., the front-to-back direction) of the high-density flow front fuselage shell, the front end of the front fuselage back structure 11 and the front end of the front fuselage belly structure 12 are connected to each other; along the transverse direction (i.e., the left-right direction) of the high-density flow front fuselage shell, the left and right ends of the front fuselage back structure 11 are respectively connected to the left and right ends of the front fuselage belly structure 12; thus, a hollow structure with a rear end opening is formed between the front fuselage back structure 11 and the front fuselage belly structure 12. In this embodiment, along the direction from the front end to the rear end of the front fuselage back structure 11, the back outer profile 111 of the front fuselage back structure 11 is an outward convex curved surface that bulges along the normal direction (i.e., the direction perpendicular to the longitudinal and transverse directions); wherein, by setting the back outer profile 111 of the front fuselage back structure 11 as an outward convex curved surface, the rear end of the high-density flow front fuselage shell is enlarged to facilitate its matching installation with other structures.

[0027] In this embodiment, along the direction from the front end to the rear end of the front fuselage belly structure 12, the belly outer surface 121 of the front fuselage belly structure 12 includes: a pre-compression surface 121a and a dense flow enhancement surface 122a connected in sequence; wherein, a transition structure (wherein, the transition structure may adopt an arc structure or a chamfered structure) is provided at the position where the pre-compression surface 121a and the dense flow enhancement surface 122a are connected. When an arc transition is adopted, the connecting position of the pre-compression surface 121a and the dense flow enhancement surface 122a is made into an arc transition, so that the connecting position is smoother and rounder, which is more beneficial to ensuring the smooth flow of the airflow; when a chamfered transition is adopted, the shock wave generated by the folded corner is used to quickly compress the airflow, thereby shortening the compression distance.

[0028] Combination Figure 1 , Figure 2 and Figure 3 As shown, according to one embodiment of the present invention, along the longitudinal direction of the high-density flow front fuselage shell, the back outer surface 111 and the belly outer surface 121 are respectively axially symmetrical surfaces; wherein, the projections of the back outer surface 111 and the belly outer surface 121 are consistent.

[0029] Combination Figure 1 , Figure 2 and Figure 3As shown, according to one embodiment of the present invention, the dense flow enhanced surface 122a includes: a forward compression surface portion 122a1, a lateral compression surface portion 122a2, and a straightening surface portion 122a3; in this embodiment, along the transverse direction of the high-density flow front fuselage shell, the lateral compression surface portion 122a2 is respectively arranged at the left and right ends of the forward compression surface portion 122a1, and the straightening surface portion 122a3 is arranged at one end of the lateral compression surface portion 122a2 away from the forward compression surface portion 122a1. In this embodiment, along the direction from the front end to the rear end of the front fuselage belly structure 12, the position where the lateral compression surface portion 122a2 is connected to the straightening surface portion 122a3 is at least partially protruded along the direction normal to away from the front fuselage back structure 11; wherein, along the direction from the front end to the rear end of the front fuselage belly structure 12, the position where the lateral compression surface portion 122a2 is connected to the straightening surface portion 122a3 can be selected to partially protrude along the direction normal to away from the front fuselage back structure 11, and of course, the position where the lateral compression surface portion 122a2 is connected to the straightening surface portion 122a3 can also be entirely protruded along the direction normal to away from the front fuselage back structure 11.

[0030] Combination Figure 1 , Figure 2 and Figure 3 As shown, according to an embodiment of the present invention, along the direction from the front end to the rear end of the front fuselage belly structure 12, the protruding height of the position where the lateral compression surface part 122a2 is connected to the straightening surface part 122a3 along the direction away from the front fuselage back structure 11 in the normal direction is variable; and the front end width of the lateral compression surface part 122a2 is greater than its rear end width, and the front end width of the straightening surface part 122a3 is less than its rear end width. Through the above arrangement, in the direction from the front end to the rear end of the front fuselage belly structure 12, the combined structure of the lateral compression surface part 122a2 and the straightening surface part 122a3 realizes the structure of the lateral contraction of the fuselage shell in the high-density flow, so that the front fuselage belly structure 12 of the present invention can more easily realize the compression enhancement of the incoming flow, and the straightening surface part 122a3 on the outside is easier for the airflow to flow through, which is more beneficial to the rapid and stable flow of the airflow.

[0031] Combination Figure 1 , Figure 2 and Figure 3 As shown, according to one embodiment of the present invention, along the lateral direction of the high-density flow front fuselage shell, the lateral compression surface portion 122a2 is provided with a recessed structure 122a21 and a raised structure 122a22 that are interconnected; wherein, the recessed structure 122a21 is arranged adjacent to the forward compression surface portion 122a1; the raised structure 122a22 is arranged adjacent to the straightening surface portion 122a3; along the direction from the front end to the rear end of the front fuselage belly structure 12, the recessed structure 122a21 and the raised structure 122a22 are arranged in sequence.

[0032] like Figure 1 As shown, according to an embodiment of the present invention, the back outer profile 111 is generated by one of the CST modeling method, PARSEC method, B-spline curve method, Hicks-Henne basis function method, FFD free deformation method, and streamline tracing method. Correspondingly, the abdominal outer profile 121 is generated by one of the CST modeling method, PARSEC method, B-spline curve method, Hicks-Henne basis function method, FFD free deformation method, and streamline tracing method.

[0033] like Figure 1 As shown, according to one embodiment of the present invention, the pre-compression profile 121a is a combination of one or more of a plane, a convex curved surface, and a concave curved surface; According to one embodiment of the present invention, the projection of the pre-compression profile 121a is an ellipse or a quasi-ellipse (e.g. Figure 4 ), triangle, quasi-triangle (such as Figure 5 ), square, quasi-square (such as Figure 6 )

[0034] Combination Figure 7 , Figure 8 , Fig. 9 , Fig.10 and Fig.11 As shown, according to one embodiment of the present invention, the back outer profile 111 and the abdomen outer profile 121 are obtained based on the following steps, which include: A two-dimensional cross-sectional shape of a corresponding outer profile (such as the back outer profile 111 or the abdomen outer profile 121) is constructed, wherein the basic shape features of the corresponding outer profile are described based on a first-class function, and the basic shape features are locally modified using a first shape function to obtain a two-dimensional cross-sectional shape; wherein the two-dimensional cross-sectional shape is expressed as: ; in, is the first shape function, is a first-class function, , , They are , , The dimensionless parameter of direction, is the intermediate function, In this embodiment, the intermediate function can be a function of various forms, such as a polynomial, an exponential, a logarithm, a power function, a trigonometric function, a piecewise function, etc., and can be selected accordingly according to the specific two-dimensional cross-sectional shape.

[0035] In this embodiment, the structural shape of each part of the abdominal outer surface 121 (such as the pre-compression surface 121a and the dense flow enhancement surface 122a) can be precisely adjusted based on the adjustment of the parameters in the two-dimensional cross-sectional shape. Therefore, each part can be further deformed in the preset spacing direction based on the following change rules to match the overall shape change of the abdominal outer surface 121.

[0036] The variation law of the two-dimensional cross-sectional shape along the flow direction is constructed, wherein the variation law is constructed based on the second shape function and the second type function; wherein the variation law is expressed as: ; in, is the longitudinal length of the high-density flow front fuselage shell from the front end to the rear end (i.e. the length direction is direction), is the second shape function, is a second-class function, is the first shape function, is a first-class function, is the section height, is the cross-section width, , , is an intermediate function, and In this embodiment, the intermediate function may adopt various forms of functions, such as polynomial, exponential, logarithm, power function, trigonometric function, piecewise function, etc., and may be selected according to the specific two-dimensional cross-sectional shape.

[0037] Based on the two-dimensional cross-sectional shape and change law, multiple external surface sections with different shapes are discretized in turn along the flow direction in three-dimensional space (see Figure 7 ), and the aerodynamic configuration of the corresponding outer surface is fitted based on the outer surface cross section (see Figure 8 , Fig. 9 , Fig.10 and Fig.11 ).

[0038] According to one embodiment of the present invention, the present invention provides a front fuselage, comprising: a front fuselage shell and airborne equipment; wherein the front fuselage shell is the aforementioned high-density flow front fuselage shell for belly-intake aircraft.

[0039] To further illustrate this solution, further examples are given.

[0040] Example 1 Based on the high-density flow front fuselage shell of the present invention, the front fuselage of a high-speed aircraft is optimized and designed. Before and after the optimization design, the overall outline and the air inlet of the two configurations are consistent. CFD calculations are carried out for the configurations before and after the optimization. Table 1 shows the average dimensionless dense flow at the inlet inlet, the flow coefficient of the inlet, and the total pressure recovery coefficient at the inlet outlet under two typical conditions.

[0041] Table 1 Dense flow and intake duct coefficient at the intake duct entrance before and after optimization by the present invention

[0042] It can be seen from Table 1 that the present invention can not only effectively improve the flow capture of the air inlet, but also reduce the flow loss.

[0043] The above contents are merely examples of specific solutions of the present invention. For devices and structures not described in detail therein, it should be understood that they can be implemented by adopting general devices and general methods available in the art.

[0044] The above is only one solution of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high-density flow front fuselage shell for a belly-intake aircraft, characterized in that: include: a forward fuselage dorsal structure (11) and a forward fuselage ventral structure (12); Along the longitudinal direction of the high-density flow front fuselage shell, the front end of the front fuselage back structure (11) and the front end of the front fuselage belly structure (12) are connected to each other; Along the lateral direction of the high-density flow front fuselage shell, the left and right ends of the front fuselage back structure (11) are respectively connected to the left and right ends of the front fuselage belly structure (12); Along the direction from the front end to the rear end of the front fuselage back structure (11), the back outer profile surface (111) of the front fuselage back structure (11) is an outward convex curved surface that bulges along the normal direction; Along the direction from the front end to the rear end of the front fuselage belly structure (12), the belly outer profile (121) of the front fuselage belly structure (12) comprises: a pre-compression profile (121a) and a dense flow enhancement profile (122a) connected in sequence; A transition structure is provided at a position where the pre-compression profile (121a) and the dense flow enhancement profile (122a) are connected.

2. The high-density flow front fuselage shell for a belly-intake aircraft according to claim 1, characterized in that: Along the longitudinal direction of the high-density flow front fuselage shell, the back outer profile (111) and the belly outer profile (121) are respectively axisymmetric profiles.

3. The high-density flow front fuselage shell for a belly-intake aircraft according to claim 2, characterized in that: The dense flow enhancement surface (122a) comprises: a forward compression surface portion (122a1), a lateral compression surface portion (122a2), and a flow straightening surface portion (122a3); Along the lateral direction of the high-density flow front fuselage shell, the lateral compression surface portion (122a2) is respectively arranged at the left and right ends of the forward compression surface portion (122a1), and the straightening surface portion (122a3) is arranged at one end of the lateral compression surface portion (122a2) away from the forward compression surface portion (122a1); Along the direction from the front end to the rear end of the front fuselage belly structure (12), the position where the lateral compression surface portion (122a2) is connected to the fairing surface portion (122a3) is at least partially protruding in a direction away from the front fuselage back structure (11) in the normal direction.

4. The high-density flow front fuselage shell for a belly-intake aircraft according to claim 3, characterized in that: Along the direction from the front end to the rear end of the front fuselage belly structure (12), the protruding height of the position where the lateral compression surface portion (122a2) is connected to the fairing surface portion (122a3) along the direction away from the front fuselage back structure (11) in the normal direction is variable; and the front end width of the lateral compression surface portion (122a2) is greater than the rear end width thereof, and the front end width of the fairing surface portion (122a3) is less than the rear end width thereof.

5. The high-density flow front fuselage shell for a belly-intake aircraft according to claim 4, characterized in that: Along the transverse direction of the high-density flow front fuselage shell, the lateral compression surface portion (122a2) is provided with a concave structure (122a21) and a convex structure (122a22) that are connected to each other; wherein the concave structure (122a21) is arranged adjacent to the forward compression surface portion (122a1); and the convex structure (122a22) is arranged adjacent to the straightening surface portion (122a3); Along the direction from the front end to the rear end of the front fuselage belly structure (12), the recessed structure (122a21) and the raised structure (122a22) are arranged in sequence.

6. The high-density flow front fuselage shell for a belly-intake aircraft according to claim 5, characterized in that: The back outer profile surface (111) is generated by using one of a CST modeling method, a PARSEC method, a B-spline curve method, a Hicks-Henne basis function method, a FFD free deformation method, and a streamline tracing method; The abdominal outer profile (121) is generated by using one of a CST modeling method, a PARSEC method, a B-spline curve method, a Hicks-Henne basis function method, a FFD free deformation method, and a streamline tracing method.

7. The high-density flow front fuselage shell for a belly-intake aircraft according to claim 6, characterized in that: The pre-compression profile (121a) is a combination of one or more of a plane, a convex curved surface, and a concave curved surface; The projection of the pre-compression profile (121a) is one of a semi-ellipse, a quasi-semi-ellipse, a triangle, a quasi-triangle, a square, and a quasi-square.

8. The high-density flow front fuselage shell for a belly-intake aircraft according to claim 7, characterized in that: The back outer profile (111) and the abdomen outer profile (121) are respectively obtained based on the following steps, which include: Constructing a two-dimensional cross-sectional shape of the corresponding outer profile, wherein the basic outer shape features of the corresponding outer profile are described based on a first-type function, and the basic outer shape features are locally corrected by a first shape function to obtain the two-dimensional cross-sectional shape; Constructing a variation rule of the two-dimensional cross-sectional shape along the flow direction, wherein the variation rule is constructed based on a second shape function and a second type function; Based on the two-dimensional cross-sectional shape and the variation rule, a plurality of external profile sections with different shapes are sequentially discretized in the three-dimensional space along the flow direction, and the aerodynamic configuration of the corresponding external profile is fitted based on the external profile sections.

9. The high-density flow front fuselage shell for a belly-intake aircraft according to claim 8, characterized in that: The two-dimensional cross-sectional shape is expressed as: in, is the first shape function, is a first-class function, , , They are , , The dimensionless parameter of direction, is the intermediate function, is the intermediate function; The variation rule is expressed as: in, It is the longitudinal length of the high-density flow front fuselage shell from the front end to the rear end, is the second shape function, is a second-class function, is the first shape function, is a first-class function, is the section height, is the cross-section width, , , is an intermediate function.

10. A front fuselage, characterized in that: include: A front fuselage shell and airborne equipment; the front fuselage shell is a high-density flow front fuselage shell for a belly-intake aircraft as described in any one of claims 1 to 9.

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