EFFECTS OF THE VARIATIONS IN THE CUMULATIVE LINER WALL THICKNESS ON THE PARAMETERS OF CUMULATIVE JET FORMATION PROCESS

The aim of the research is to study the formation of cumulative jets in charges with cumulative facings with a wall thickness of the order of the thickness of the jet-forming layer in classical charges. Based on mathematical modeling and experiments, it is shown that in such charges, the detonation products of explosives can play the role of an additional body that affects the axial velocity of the lin-ing throwing and leads to a collapse angle of more than 180 degrees. In this process, the mass of the jet is greater than the mass of the pestle. For the first time, corrugations were experimentally detected on the surface of the lining during its explosive compression. Corrugations may occur on the surface of the lining, leading to instability of the cumulative jet formation process. As a result of the study, it was found that the minimum wall thickness of the cladding is mainly determined by the instability of its surface (the appearance of corrugations on its surface).

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First Evidence of Flux Transfer Events Caused by Mangetosheath Jets

10.5194/egusphere-egu2020-811 ◽

2020 ◽

Author(s):

Simon Thor ◽

Anita Kullen ◽

Tomas Karlsson ◽

Savvas Raptis

Keyword(s):

Formation Process ◽

Statistical Study ◽

Dynamic Pressure ◽

Background Level ◽

Jet Formation ◽

Flux Transfer Events ◽

Reconnection Region ◽

Close Proximity ◽

Flux Transfer ◽

First Time

Magnetosheath jets are local enhancements of dynamic pressure above the background level. Hietala et al. (2018) recently presented observational evidence of a jet collision with the magnetopause causing magnetic field line reconnection. In the present study, we show data which, for the first time, strongly indicates that magnetosheath jets can even create localized transient reconnection events, so-called flux transfer events (FTEs).FTEs are commonly observed in cascades with an average separation time of 8-10 minutes, but may also appear as isolated events. Despite the fact that FTEs have gained major attraction during recent years, the formation process of FTEs is not yet fully understood. We showed in a recent statistical study (Kullen, Thor, and Karlsson; 2019) that isolated FTEs and FTE cascades occur during different IMF conditions and are differently distributed along the magnetopause. The results of the statistical study strongly suggest that the majority of the FTEs formed along the expected reconnection region for each respective IMF condition. However, for a subset of isolated FTEs, we proposed a different formation process. These events may have been caused by magnetosheath jets, as they occur during IMF conditions favorable for jet formation. Simulation results by Karimabadi et al. (2014) has shown that such a creation mechanism is possible. In his simulation, a magnetosheath jet collides with the magnetopause, creating an FTE.In the present investigation, FTEs that may have been caused by magnetosheath jets were identified. To achieve this, we examined measurements from all four Cluster satellites, and searched for magnetosheath jets that appear in close proximity to FTEs listed in Wang et al. (2005)&#8217;s FTE list. Our results show that approximately 15% of isolated FTEs appear in the vicinity of jets. These FTEs are further examined based on IMF and location across the magnetopause. For two of the FTEs, the associated jet appears close to the magnetopause. We present a detailed data analysis of these two events and discuss a possible formation mechanism for the FTEs, as there is strong evidence that the two FTEs are indeed caused by jets.

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Influence of material viscosity on the jet formation process during collisions of metal plates

Combustion Explosion and Shock Waves ◽

10.1007/bf00742849 ◽

1976 ◽

Vol 11 (1) ◽

pp. 1-13 ◽

Cited By ~ 18

Author(s):

S. K. Godunov ◽

A. A. Deribas ◽

V. I. Mali

Keyword(s):

Formation Process ◽

Jet Formation ◽

Metal Plates

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Methodology for simulation of the jet formation process in an elongated shaped charge

Combustion Explosion and Shock Waves ◽

10.1134/s0010508214030150 ◽

2014 ◽

Vol 50 (3) ◽

pp. 362-367 ◽

Cited By ~ 4

Author(s):

A. Wojewódka ◽

T. Witkowski

Keyword(s):

Formation Process ◽

Shaped Charge ◽

Jet Formation

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Kinematics of the shaped charge jet formation process

Journal of Physics Conference Series ◽

10.1088/1742-6596/1666/1/012017 ◽

2020 ◽

Vol 1666 ◽

pp. 012017

Author(s):

E M Grif ◽

A V Guskov ◽

K E Milevskii

Keyword(s):

Formation Process ◽

Shaped Charge ◽

Jet Formation ◽

Shaped Charge Jet

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Formation and Penetration Capability of an Annular-Shaped Charge

Mathematical Problems in Engineering ◽

10.1155/2021/6660189 ◽

2021 ◽

Vol 2021 ◽

pp. 1-14

Author(s):

Zhecheng Hu ◽

Zhijun Wang ◽

Jianping Yin ◽

Jianya Yi

Keyword(s):

Formation Process ◽

High Energy ◽

Calculation Model ◽

Shaped Charge ◽

High Energy Density ◽

Damage Effect ◽

Jet Formation ◽

Annular Jet ◽

Underwater Structure ◽

Two Parameters

Shaped charges are widely used in the field of national defense because of their high energy density and strong directivity; however, one of their limitations is that the penetration diameter is small. Compared with a traditional shaped charge, an annular-shaped charge can create a larger penetration aperture at the target, thereby causing more damage to underwater targets. To enhance the damage effect of a shaped charge on an underwater structure, we designed an annular-shaped charge structure. To end this, we first established a velocity calculation model of the liner and analyzed its formation process. The hydrocode software Autodyn was used to simulate the jet formation process. Second, two parameters of the annular liner height and thickness of the bottom and their effect on the annular jet formation were analyzed. Finally, an experiment was conducted to validate the penetration capability of this charge. The experimental results indicate that the annular-shaped charge can penetrate a typical underwater structure and form a large penetration aperture with a diameter of 420 mm, which is 1.4 times the charge diameter. Furthermore, the numerical results show good agreement with the experimental data; only a 1.67% deviation was observed.

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Some Possibilities of Hypercumulative Regime of Jet Formations

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.782.42 ◽

2015 ◽

Vol 782 ◽

pp. 42-48 ◽

Cited By ~ 1

Author(s):

Vladilen Minin ◽

Oleg Minin ◽

Igor Minin

Keyword(s):

Stagnation Point ◽

Formation Process ◽

Constant Pressure ◽

Dead Zone ◽

Smoothing Effect ◽

Jet Formation ◽

Classical Scheme ◽

Physical Problems ◽

Different Types ◽

Rayleigh Taylor Instability

Basic physical problems of jet formation process on the basis of Lavrentiev-Birkhoff classical scheme are analyzed. It is shown that in process of realization of hypercumulation conditions for jet formation without complete stagnation point involving formation of the inner zone of constant pressure (dead zone), the flow mass is always greater than slug mass, that is unachievable in the known models. Smoothing effect of this zone on the development of different types disturbances, particularly, smoothing Rayleigh-Taylor instability for thin liner may be expected and shown in simulations.

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Numerical Study on the Electrohydrodynamic Jet Printing

Journal of Micro and Nano-Manufacturing ◽

10.1115/1.4049820 ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

Xue Yang ◽

Shuobang Wang ◽

Zhifu Yin ◽

Jili Wang ◽

Wei Hu

Keyword(s):

Flow Rate ◽

Applied Voltage ◽

Formation Process ◽

High Efficiency ◽

Numerical Study ◽

Low Cost ◽

Element Model ◽

Jet Formation ◽

Electrohydrodynamic Jet Printing ◽

Jet Printing

Abstract Electrohydrodynamic (EHD) printing is an alternative method to fabricate high-resolution micro- and nanostructures with high efficiency, low cost, and low pollution. Numerical simulation is an effective approach to systematically investigate the formation process of EHD jet. However, there are a few articles performing this work. In this study, a finite element model was established. The jet formation process and jetting modes were analyzed. The influence of applied voltage and printing distance on the maximum electric field near the nozzle tip was investigated. The effect of flow rate on the jet diameters was studied. Comparison between numerical and experimental results demonstrated that the proposed simulation model had a high potential for EHD jet analysis. According to the optimized printing conditions (printing distance of 200–300 μm, applied voltage of ∼1100 V, and flow rate of 0.1–0.3 ml/h), stable EHD jet can generate and polyvinyl pyrrolidone (PVP) lines with minimum line-width of 0.9 μm can be printed onto the glass slide.

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