CN110542354B

CN110542354B - Design method of energy-gathered charge supercavity projectile

Info

Publication number: CN110542354B
Application number: CN201910829237.3A
Authority: CN
Inventors: 荣光; 王康健; 王金相; 赵子杰
Original assignee: Nanjing University of Science and Technology
Current assignee: Nanjing University of Science and Technology
Priority date: 2019-09-03
Filing date: 2019-09-03
Publication date: 2022-10-21
Anticipated expiration: 2039-09-03
Also published as: CN110542354A

Abstract

The invention discloses a design method of an energy-gathered charge supercavity projectile, which aims to improve the end penetration performance of an underwater supercavity uncontrolled kinetic energy projectile, realizes the functions of remote navigation and efficient damage by combining an energy-gathered charge technology with good damage performance in the air with a supercavity technology with range-extending resistance reduction capability, and provides a new idea for designing underwater supercavity projectiles.

Description

Design method of energy-gathered charge supercavity projectile

Technical Field

The invention relates to the field of design of underwater supercavitation ammunition, in particular to a design method of an underwater supercavitation projectile structure for efficient damage.

Background

The shaped charge technology has a plurality of excellent properties and a wide application field. But the jet type underwater damage prevention device is mainly used for land battles, and even if the jet type underwater damage prevention device is used for underwater damage, the jet type underwater damage prevention device is only launched on the water surface, the action effect of jet flow is limited by water media, the damage range is limited in a shallow water area, and the due penetration power of the jet type underwater damage prevention device is greatly reduced. How to enable the energy-collecting explosive charge to play the due damage effect underwater becomes one of the major problems to be solved, and the method has important significance for expanding the application field of the energy-collecting explosive charge.

In the middle of the 20 th century, the proposal of the underwater supercavitation projectile technology provides a new development idea for the range-increasing drag reduction of the underwater projectile. The supercavity projectile technology is a technology that when the projectile moves at high speed underwater, the surface pressure of the projectile is reduced, cavitation bubbles generated after the fluid is vaporized completely wrap the projectile, the contact between the projectile and the water is isolated, and the fluid friction resistance on the surface of the projectile is reduced to 0. The projectile greatly reduces the consumption of the kinetic energy of the projectile and achieves the purpose of increasing the range and reducing the drag. If the energy-collecting charge technology can be combined with the super-cavity projectile technology, the damage performance of the projectile can be increased on the basis of increasing the range of the projectile, and the application prospect is good.

Disclosure of Invention

The invention aims to provide a design method of an energy-collecting charge supercavity projectile structure, aiming at realizing the perfect combination of an energy-collecting charge technology and a supercavity technology by reasonably designing the projectile structure.

The technical solution for realizing the invention is as follows: the design method of the energy-gathered charge supercavity projectile structure comprises the following steps:

step 1, determining the advantageous explosive height of a V-shaped liner by using computer simulation according to the V-shaped liner structure, and determining the length of the head of a supercavitation projectile;

and 2, setting the diameter of the initial cavitator to be consistent with the diameter of the cartridge, calculating the size of the cavitation bubble at the maximum section of the projectile under the designed projectile length through a Lobvionch independent expansion equation, continuously reducing the size of the cavitator, and circularly calculating until the size of the cavitation bubble at the maximum section of the projectile meets the design requirement.

Compared with the prior art, the invention has the remarkable advantages that: 1) The design of the invention perfectly combines the advantages of two technologies, enhances the damage performance of the resistance-reducing and the range-increasing simultaneously, and 2) the design process of the invention is simple and easy to operate, the whole design process can be realized by a computer, and the computer analysis can be carried out on the design result. 3) The invention improves the shot launching method, does not increase the shot launching difficulty and the water entering difficulty, transfers the damage mode of the kinetic energy shot, is convenient for low-speed launching and reduces overload.

Drawings

FIG. 1 is a flow chart of the method of the present invention.

Figure 2 is a three-dimensional structure of a shaped charge.

FIG. 3 is a cloud of air shaped charge jet densities.

FIG. 4 is an integral of a velocity time course curve of 1000m/s or more.

Figure 5 is a typical supercavitation shot configuration.

FIG. 6 is a static simulated density cloud of penetration of air and underwater shaped charge supercavitation shots.

FIG. 7 is a pressure cloud and damage scenario for air (left) and underwater (right) targets.

Detailed Description

The invention will be further described with reference to the accompanying drawings and specific examples.

Referring to fig. 1, a method of designing a shaped charge supercavity projectile includes the steps of:

step 1, according to the sizes of a V-shaped liner and a loading cylinder, carrying out energy-gathering jet simulation calculation in the air by using a computer, simultaneously carrying out a jet penetration test in the air and comparing the result with a corresponding simulation result, if the simulation result is consistent with the test result, integrating an independent variable with a jet head speed time-course curve function value of more than 1000m/s to obtain a favorable explosion height h, and using the favorable explosion height h obtained by calculation as the head length of the supercavity projectile;

and 3, setting the diameter of the initial cavitator to be consistent with the diameter of the loading cylinder, calculating the size of the cavitation bubble at the maximum section of the projectile under the designed projectile length through a Lobvivich independent expansion equation, continuously reducing the size of the cavitator, and circularly calculating until the size of the cavitation bubble at the maximum section of the projectile reaches 3-5 times of the maximum size, wherein the design requirement is met.

Example 1

Fig. 2 is a vertical design of a shaped charge, which itself is designed to have good damage performance and jet morphology in air, and table 1 is the geometric dimensions of the shaped charge. In order to save computing resources and accelerate the computing speed, the model needs to be properly simplified, and the model is in an axisymmetric structure, so that 1/4 modeling is adopted. ANSYS LS-DYNA is used for three-dimensional modeling, and a g-cm-mus unit system is adopted. The calculation model comprises an aluminum cartridge, a PBX-9010 explosive, a red copper shaped charge cover, air/water and the like, wherein the cartridge is modeled by a Lagrange grid, the rest part of the cartridge is modeled by an Euler grid due to excessive deformation, the Euler grid is used for achieving the purpose of coupling, and the grids are all SOLID164 calculation units.

TABLE 1 calculation of model parameters

Medicine loading per gram	31.8
		Liner thickness/mm	2.0
Thickness of the outer shell/mm	2.0
		Diameter of charge/mm	26
Diameter/mm of warhead	30.0
		Charge diameter/mm	26.0
Distance/mm between ignition point and shaped charge liner	11

When the energy-gathered jet penetrates the target, the damage effect is mainly in the head area of the jet, so the most critical factor for determining the high explosion benefit of the energy-gathered jet is the speed of the head of the jet, and fig. 3 is a density cloud chart of the air energy-gathered charge jet. Fig. 4 is an integration of the velocity time course curve over 1000m/s, it can be seen that the velocity peaks are concentrated between 0-0.0002s, and thus the advantageous burst height lies within this time interval. In order to ensure that the homogeneous charge jet has better penetration performance, the lowest penetration speed of the head speed of the homogeneous charge jet is limited to 1000m/s, so that the integral of the speed time curve of the speed of 0-0.0002s and more than or equal to 1000m/s can obtain the lower limit of favorable explosion height of 13.7cm and the caliber of a warhead part of the homogeneous charge jet in the range of 3-8 times of the favorable explosion height of the homogeneous charge jet, wherein the caliber of the warhead part of the homogeneous charge is 9-24cm for the warhead part of the homogeneous charge, as shown in FIG. 4. The calculation result is basically consistent with the experience within the interval, namely 9-13.7cm. The design calculation herein takes 12cm as the internal length of the shaped charge supercavitation bullet.

Table 2 shows the calculation results of the cavitation diameter at the maximum diameter of the projectile (the maximum diameter of the projectile is 30 mm) under three conditions, the cavitation device of the three sizes meets the calculation requirements in terms of numerical values, from the practical point of view, the difference between the cavitation generated by the cavitation device No. 1 and the diameter of the projectile is small, under the condition, the shaped charge super-cavitation projectile is easy to contact with the wall surface of the cavitation due to small disturbance, and the good resistance reduction performance of the super-cavitation projectile is completely lost. Although the No. 2 cavitator has a reasonable cavitation diameter, the size of the cavitator is too small from the perspective of the penetration of the energy-gathered jet, the energy-gathered jet cannot move strictly according to a designed track in the actual forming process, and the jet forms are not uniform due to the non-uniformity of explosive ignition, so when the cavitator is too small, the jet possibly penetrates out from the side surface of a projectile and penetrates into the target after moving in water for a period of time, the penetration performance of the energy-gathered jet is reduced, and the designed hollow head loses the function of enabling the jet to form the optimal penetration form. In order to ensure the penetration performance of the energy-gathered jet and simultaneously meet the resistance reduction requirement of the movement of the supercavitation projectile, a 20mm cavitator is adopted as a design size. The traditional supercavity projectile head cavitator usually has certain size and thickness as shown in figure 5, but the damage mechanism of the traditional supercavity projectile is mainly the kinetic energy of the supercavity projectile, while the main damage mechanism of the energy-gathered charge supercavity projectile is energy-gathered jet flow.

TABLE 2 calculation of the cavitation diameter at the maximum diameter of the projectile

Serial number	Diameter of cavitator (mm)	Diameter of cavity (mm) at maximum diameter of projectile
			1	5	64.4
2	10	94.15
			3	20	138.78

The wall thickness of the head of the supercavity projectile is designed to be 2mm by considering the factor of convenient processing, and the head of the projectile can be ensured to be well matched with a cartridge case of shaped charge from the aspect of the other aspect.

Fig. 6 is a density comparison cloud of the penetration of the air and the underwater shaped jet, and it can be seen that there is no difference between the air and the water when the detonation waves generated after the ignition of the explosive do not reach the shaped charge cartridge and the shaped charge liner, the cartridge in the air is rapidly broken at 3 μ s when the detonation waves reach the shaped charge cartridge, while the underwater cartridge is flexed by the presence of the "support" of the water and is broken after 6 μ s as time progresses, while a metal jet is formed in both media and moves forward at high speed, the underwater shaped jet penetrates the cavitator first at 40 μ s to penetrate the target, the shaped jet in the air also starts to penetrate the target at 44.99 μ s, comparing the penetration of the jet at 44.99 μ s and 51 μ s, it can be seen that the underwater shaped jet has higher kinetic energy at the penetration, has larger opening at the moment of striking the target than the shaped jet in the air (fig. 7), and the reason for this phenomenon is: for the explosion of the shaped charge in the air, the media at the back of the charge cylinder and the liner are the same, so that the difference between the reflected pressure wave and the transmitted pressure wave generated by the detonation wave at the back of the charge cylinder and the liner is very small, and the detonation wave is uniform on the whole; however, under water, the medium on the back of the medicine cylinder is water, the medium on the back of the shaped charge cover is air, so that the expanding speed of explosive gas is different, the energy generated by explosion can be quickly dissipated due to low air density, but the density of water is far greater than that of air, so that the energy can be gathered in a short time, the energy dissipated by explosion is slow, the time acting on the shaped charge cover is slightly longer than that in the air, so that the damage performance of energy-gathered jet under water is better than that of air, meanwhile, the underwater situation of the head of the bullet is greatly deformed at the part connected with the aluminum medicine cylinder, and the internal pressure of the head of the bullet is unequal due to different fluid media, so that the deformation of the head of the bullet is caused by radial pressure.

In view of the above example, it can be seen that the two techniques combined provide greater damage capability under water than in air.

Claims

1. A method of designing a shaped charge supercavity projectile comprising the steps of:

step 1, determining the advantageous explosive height of a V-shaped liner by using computer simulation according to the V-shaped liner structure, and determining the length of the head of a supercavitation projectile; the geometric dimensions of the shaped charge are: the charge amount is 31.8g, the thickness of the shaped charge liner is 2.0 mm, the thickness of the shell is 2.0 mm, the charge diameter is 26 mm, the diameter of the warhead is 30.0 mm, the charge diameter is 26.0 mm, and the distance between the ignition point and the shaped charge liner is 11 mm;

step 2, setting the diameter of the initial cavitator to be consistent with the diameter of the loading cylinder, calculating the size of the cavitation bubble at the maximum section of the projectile under the designed projectile length through a Lobvivich independent expansion equation, continuously reducing the size of the cavitator, and circularly calculating until the size of the cavitation bubble at the maximum section of the projectile meets the design requirement; the diameter of the cavitator is 5 mm, the diameter of the cavitation bubble at the maximum diameter of the projectile is 64.4 mm, the diameter of the cavitator is 10 mm, the diameter of the cavitation bubble at the maximum diameter of the projectile is 94.15 mm, the diameter of the cavitator is 20mm, and the diameter of the cavitation bubble at the maximum diameter of the projectile is 138.78 mm.