Air suction type bottom concave cavity drag reduction structure and range-extending cannonball with air suction type bottom concave cavity drag reduction structure

Abstract

The invention discloses an air suction type bottom cavity drag reduction structure and a range-extending shell with the same, and belongs to the technical field of aircraft such as shells and missiles, the air suction type bottom cavity drag reduction structure comprises a V-shaped cavity bottom surface and an air suction lip cover; the bottom surface of the V-shaped concave cavity is arranged in the air suction lip cover, and the V-shaped concave cavity and the air suction lip cover are coaxially fixed through supporting ribs extending from the outer side of the bottom surface of the V-shaped concave cavity; a circular seam is formed between the outer surface of the bottom surface of the V-shaped concave cavity and the inner surface of the air suction lip cover, so that an annular flow channel is formed; the bottom surface of the V-shaped concave cavity comprises a plurality of circular seam concave cavities and a top concave cavity, the plurality of circular seam concave cavities are arranged at intervals along the outer surface of the bottom surface of the V-shaped concave cavity, and the top concave cavity is arranged at one end of the bottom surface of the V-shaped concave cavity. High-speed air flow kinetic energy is converted into pressure energy through oblique shock wave pressurization and aerodynamic deceleration diffusion principles, so that the bottom pressure of the projectile and rocket aircraft is improved, the bottom resistance is reduced, and meanwhile the requirement for low-wave-resistance appearance aerodynamic layout design of the projectile and rocket aircraft is lowered.

Description

Technical Field

[0001] The present invention belongs to the technical field of artillery shells, missiles and other aircraft, and more specifically, relates to an air-breathing bottom cavity drag reduction structure and an extended-range artillery shell having the structure. Background Art

[0002] When a missile-rocket aircraft flies at high speed in the atmosphere, its drag characteristics have a direct impact on the range, payload weight, thrust-to-weight ratio and other characteristics of the missile-rocket aircraft. Therefore, drag reduction has always been the primary task in the design of high-speed missile-rocket aircraft. In terms of the formation mechanism of the resistance encountered by the missile-rocket aircraft during high-speed flight, the drag of the missile-rocket aircraft is mainly composed of friction resistance, wave resistance and bottom resistance. Based on this, people have carried out a large number of drag reduction and lift increase designs from the aspects of optimizing the aircraft's appearance structure, increasing thrust and increasing bottom pressure. Patent application CN202010667681.2 proposes a coaxial parallel charge bottom discharge drag reduction and bottom separation and mass reduction design, which reduces drag and increases thrust while taking into account the weight of the payload, and has a certain beneficial effect. Patent application CN202011222265.8 rectifies the traditional cylindrical aerodynamic shape into a jujube-shaped aerodynamic layout from the perspective of passive rectification, achieving the beneficial effect of reducing flight resistance.

[0003] As an important component of the flight resistance of missile and rocket aircraft, the bottom resistance accounts for about 40% to 50% of the total resistance according to literature reports. Reducing the bottom resistance is of great significance to high-speed missile and rocket aircraft. From the technical route, the bottom resistance is currently mainly reduced by two means: bottom discharge (such as patent application CN201010594424.7 and patent application CN201010594415.8) and bottom concave. The bottom concave method has the characteristics of simple structure, good adaptability to the flight envelope, and no additional complex auxiliary components. It is still one of the main methods commonly used to reduce the bottom resistance, but the effect of reducing the bottom resistance by this method is not ideal. Therefore, how to further reduce the bottom resistance on the basis of the bottom concave method is a problem that needs to be solved urgently by technical personnel in this field. Summary of the invention

[0004] In view of the above defects or improvement needs of the prior art, the present invention provides an air-breathing bottom concave cavity drag reduction structure and an extended-range artillery shell having the structure, the purpose of which is to capture the high-speed incoming air on the surface of the aircraft by using parallel beveled air inlets at the tail of the rocket aircraft, thereby solving the technical problem that the bottom concave method has a poor effect in reducing bottom resistance.

[0005] To achieve the above-mentioned object, according to one aspect of the present invention, there is provided an air-intake bottom cavity drag reduction structure, comprising: a V-shaped cavity bottom surface and an air-intake lip cover; the V-shaped cavity bottom surface is arranged inside the air-intake lip cover, and the two are coaxially fixed by supporting ribs extending from the outside of the V-shaped cavity bottom surface; an annular gap is provided between the outer surface of the V-shaped cavity bottom surface and the inner surface of the air-intake lip cover to form an annular flow channel;

[0006] The bottom surface of the V-shaped cavity includes a plurality of annular slit cavities and a top cavity. The plurality of annular slit cavities are arranged at intervals along the outer surface of the bottom surface of the V-shaped cavity. The top cavity is arranged at one end of the bottom surface of the V-shaped cavity.

[0007] Preferably, the lip of the air suction lip mask is an annular beveled lip, the bevel angle of the annular beveled lip meets the aerodynamic conditions for forming a body-fitting oblique shock wave, and the bevel angle is 2° to 10°.

[0008] Preferably, an annular air intake inlet with a uniform gap is formed between the annular chamfered lip and the bottom surface of the V-shaped cavity.

[0009] Further preferably, the width of the annular air intake inlet satisfies a certain aerodynamic relationship with the bevel angle of the annular bevel lip and the semi-opening angle of the bottom surface of the V-shaped cavity, so that the body-fitting oblique shock wave generated at the annular bevel lip can intersect with the bottom surface of the V-shaped cavity.

[0010] Preferably, the cross-sectional area of ​​the annular flow channel gradually expands along the gas flow direction to meet the requirements of deceleration and expansion of the inhaled high-speed airflow; and the annular flow channel extends along the gas flow direction to the rear of the suction lip cover to form a bottom concave cavity.

[0011] Preferably, the half angle of the bottom surface of the V-shaped cavity is 15° to 30°.

[0012] Preferably, the shape of the inhalation lip mask forms a zero attack angle with the gas flow direction to avoid generating additional aerodynamic resistance.

[0013] Preferably, the diameter-to-depth ratio of the top cavity is 2-4:1.

[0014] Further preferably, the diameter-to-depth ratio of the concave cavity structure formed by the outward extension length of the suction lip shield and the end surface of the top concave cavity is 2-4:1.

[0015] Preferably, a plurality of annular slit cavities are distributed at equal intervals on the outer surface of the bottom surface of the V-shaped cavity.

[0016] Preferably, the ratio of the width to the depth of the annular cavity is 2 to 4:1.

[0017] According to another aspect of the present invention, there is provided an extended-range artillery shell, comprising the above-mentioned air-breathing bottom concave cavity drag reduction structure, and further comprising: a conical warhead, a first cylindrical body and a second cylindrical body, wherein one end of the conical warhead is provided with the first cylindrical body, one end of the first cylindrical body is provided with the second cylindrical body, and one end of the second cylindrical body is provided with the air-breathing bottom concave cavity drag reduction structure;

[0018] The body diameter of the first cylindrical body is greater than the body diameter of the second cylindrical body, so that a rear step is formed at the connection between the first cylindrical body and the second cylindrical body.

[0019] In general, compared with the prior art, the above technical scheme conceived by the present invention can achieve the following beneficial effects: the present invention provides an air-breathing bottom cavity drag reduction structure and an extended-range projectile with the structure, and an air intake lip cover is arranged at the tail end of a high-speed missile and arrow aircraft, so that the naturally existing high-speed airflow near the wall of the high-speed missile and arrow aircraft is sucked into the cross-sectional area expansion annular flow channel formed by the air intake lip cover and the bottom surface of the V-shaped cavity at the tail end, and the high-speed airflow is decelerated and expanded, and the pressure at the bottom of the aircraft is restored to a certain extent. At the same time, the high-speed airflow interacts with the annular beveled lip at the lip of the air intake lip cover to produce an oblique shock wave. The intersection of the oblique shock wave extension line and the bottom surface of the V-shaped cavity at the tail end will further increase the bottom pressure of the aircraft, thereby greatly reducing the bottom drag loss of the missile and arrow aircraft. While having the advantages of traditional bottom concave drag reduction technology, it has the advantages of no moving parts, strong adaptability to the flight envelope, and strong stability in bottom drag reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of a specific projectile embodiment of the air-breathing bottom concave cavity drag reduction structure of the present invention;

[0021] Figure 2 It is a structural schematic diagram of the bottom surface of the V-shaped concave cavity in the air-intake bottom concave cavity drag reduction structure of the present invention;

[0022] Figure 3 It is a schematic diagram of the air intake process of the air intake type bottom concave cavity drag reduction structure in the present invention.

[0023] In all the drawings, the same figure numbers are used to represent the same elements or structures, among which: 1-conical warhead; 2-first cylindrical body; 3-second cylindrical body; 4-annular beveled lip; 5-intake lip cover; 6-bottom cavity; 7-support ribs; 8-V-shaped cavity bottom surface; 9-annular cavity; 10-top cavity; 11-rear step; 12-oblique shock wave. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] like Figure 1-3 As shown, the present invention proposes an air-intake bottom cavity drag reduction structure, which breaks through the traditional bottom cavity design that relies on passive vortex supercharging, adopts active air intake, and uses the principle of oblique shock wave supercharging and gas deceleration and expansion to increase the bottom cavity pressure to reduce the bottom resistance. The structure mainly includes a V-shaped cavity bottom surface 8 and an air intake lip cover 5, the V-shaped cavity bottom surface 8 and the air intake lip cover 5 are coaxially arranged, the lip diameter of the air intake lip cover 5 is larger than the diameter of the V-shaped cavity bottom surface 8, and the annular seam structure formed constitutes an air intake inlet, and the outer surface of the V-shaped cavity bottom surface 8 is coaxially arranged with a plurality of annular seam cavities 9 and a top cavity 10, four supporting ribs 7 are arranged on the outside of the top cavity 10, and the supporting ribs 7 are connected to the air intake lip cover 5, so that the V-shaped cavity bottom surface 8 and the air intake lip cover 5 are fixed relative to each other as a whole, and the lip of the air intake lip cover 5 adopts an annular beveled lip and is coaxially arranged in the incoming flow direction.

[0026] Specifically, Figure 1 and Figure 2 As shown, an example of the present invention provides an extended-range projectile with an air-breathing bottom cavity drag reduction structure, including a conical warhead 1, a first cylindrical body 2, a second cylindrical body 3 and an air-breathing bottom cavity drag reduction structure. Furthermore, the air-breathing bottom cavity drag reduction structure is composed of a V-shaped cavity bottom surface 8 and an air-breathing lip cover 5, and the two are coaxially fixed relative to each other as a whole through four supporting ribs 7 extending outward from the outside of the top cavity 10, and the supporting ribs 7 are at an angle of 90°. In order to further enhance the drag reduction effect of the bottom cavity, a series of annular seam cavities 9 and top cavities 10 are arranged at equal intervals on the surface of the V-shaped cavity bottom surface 8. The lip of the air-breathing lip cover 5 is beveled to form an annular beveled lip 4.

[0027] Further explanation, the surface of the V-shaped concave cavity bottom surface 8 is arranged inside the air intake lip cover 5, and there is a uniform gap between the surface of the V-shaped concave cavity bottom surface 8 and the annular chamfered lip 4, forming an air intake inlet. The shell of the air intake lip cover 5 is arranged horizontally and forms a diffuser channel with a gradually increasing flow channel cross-sectional area between the surface of the V-shaped concave cavity bottom surface 8, and its further extended part forms a bottom concave cavity 6.

[0028] To further explain, the diameter of the second cylindrical body 3 is smaller than that of the first cylindrical body 2, forming a rear step 11. The rear step 11 is arranged before the annular beveled lip 4 to form an expansion reflux zone, which reduces the air flow velocity at the inlet of the annular beveled lip 4 to a certain extent and reduces the wave resistance of the projectile.

[0029] The technical solution of the present invention is further illustrated by means of specific embodiments below.

[0030] like Figure 3 As shown, after the shell is fired, a high-speed flow field will be generated around the first cylindrical body 2. After the rear step 11 between the first cylindrical body 2 and the second cylindrical body 3 expands, the high-speed flow field around the first cylindrical body 2 will be decelerated to a certain extent, and it will also have the beneficial effect of reducing the overall wave resistance loss of the shell. After being decelerated by the rear step 11, the air flow velocity around the surface of the second cylindrical body 3 will enter the subsonic region or the supersonic region with a small Mach number, and will be sucked into the air-intake bottom cavity drag reduction structure from the uniform annular gap between the surface of the V-shaped cavity bottom surface 8 and the annular beveled lip 4. If the suction flow is supersonic, an oblique shock wave 12 will be generated at the leading edge of the annular beveled lip 4, and the air flow velocity after the oblique shock wave 12 will be reduced to subsonic while the gas pressure increases. When the incoming air velocity is reduced to subsonic after the oblique shock wave 12 or is subsonic itself, the airflow velocity will be further decelerated after entering the cross-sectional area gradually expanding flow channel formed between the air intake lip cover 5 and the surface of the V-shaped concave cavity bottom surface 8, and the airflow kinetic energy will be further converted into gas pressure energy, thereby increasing the pressure on the surface of the V-shaped concave cavity bottom surface 8 and reducing the bottom resistance of the projectile. In order to maximize the drag reduction effect of the bottom concave structure on the bottom resistance of the projectile, a top concave cavity 10 and an annular seam concave cavity 9 are set at the top of the surface of the V-shaped concave cavity bottom surface 8. When the airflow flows through the surface of the V-shaped concave cavity bottom surface 8, a backflow will be generated in these concave cavities, so that the airflow pressure is further restored.

[0031] The salient features of the air-intake bottom cavity drag reduction structure of the present invention are as follows: a horizontal air-intake lip cover structure is arranged at the tail end of the missile-rocket aircraft, which actively inhales the high-speed airflow flowing around the missile-rocket aircraft without significantly increasing the friction and wave resistance of the aircraft, and converts the kinetic energy of the high-speed airflow into pressure energy through the oblique shock wave boost and aerodynamic deceleration and diffusion principles, thereby increasing the bottom pressure of the missile-rocket aircraft, reducing the bottom resistance and reducing the requirements for the aerodynamic layout design of the low wave resistance shape of the missile-rocket aircraft.

[0032] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An air-breathing bottom cavity drag reduction structure, characterized in that: include: A V-shaped concave cavity bottom surface (8) and an air suction lip cover (5); the V-shaped concave cavity bottom surface (8) is arranged inside the air suction lip cover (5), and the two are coaxially fixed by a supporting rib (7) extending outside the V-shaped concave cavity bottom surface (8); an annular gap is provided between the outer surface of the V-shaped concave cavity bottom surface (8) and the inner surface of the air suction lip cover (5) to form an annular flow channel; The V-shaped concave cavity bottom surface (8) comprises a plurality of annular slit concave cavities (9) and a top concave cavity (10), wherein the plurality of annular slit concave cavities (9) are arranged at intervals along the outer surface of the V-shaped concave cavity bottom surface (8), and the top concave cavity (10) is arranged at one end of the V-shaped concave cavity bottom surface (8).

2. The air-breathing bottom cavity drag reduction structure according to claim 1, characterized in that: The lip opening of the air suction lip mask (5) is an annular beveled lip opening (4), and the bevel angle of the annular beveled lip opening (4) is 2° to 10°.

3. The air-breathing bottom cavity drag reduction structure according to claim 2, characterized in that: An annular air intake inlet with a uniform gap is formed between the annular beveled lip and the surface of the bottom surface (8) of the V-shaped cavity.

4. The air-breathing bottom cavity drag reduction structure according to claim 1, characterized in that: The cross-sectional area of ​​the annular flow channel gradually expands along the gas flow direction, and the annular flow channel extends along the gas flow direction to the rear of the suction lip mask (5) to form a bottom concave cavity (6).

5. The air-breathing bottom cavity drag reduction structure according to claim 1, characterized in that: The half angle of the bottom surface (8) of the V-shaped cavity is 15° to 30°.

6. The air-breathing bottom cavity drag reduction structure according to claim 1, characterized in that: The shape of the suction lip mask (5) forms a zero attack angle with the incoming gas flow direction.

7. The air-breathing bottom cavity drag reduction structure according to claim 1, characterized in that: The diameter-to-depth ratio of the top concave cavity (10) is 2-4:

1.

8. The air-breathing bottom cavity drag reduction structure according to claim 1, characterized in that: A plurality of annular slit concave cavities (9) are distributed at equal intervals on the outer surface of the V-shaped concave cavity bottom surface (8).

9. The air-breathing bottom cavity drag reduction structure according to claim 8, characterized in that: The ratio of the width to depth of the annular concave cavity (9) is 2 to 4:

1.

10. An extended-range artillery shell, characterized in that: The invention comprises an air-breathing bottom cavity drag reduction structure as described in any one of claims 1 to 9, and further comprises: a conical bullet head (1), a first cylindrical bullet body (2) and a second cylindrical bullet body (3), wherein one end of the conical bullet head (1) is provided with the first cylindrical bullet body (2), one end of the first cylindrical bullet body (2) is provided with the second cylindrical bullet body (3), and one end of the second cylindrical bullet body (3) is provided with the air-breathing bottom cavity drag reduction structure; The diameter of the first cylindrical body (2) is greater than the diameter of the second cylindrical body (3), so that a rear step (11) is formed at the connection between the first cylindrical body (2) and the second cylindrical body (3).

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