Natural Supercavitation Characteristic Simulation of Small-Caliber Projectile

2014 ◽  
Vol 488-489 ◽  
pp. 1243-1247 ◽  
Author(s):  
Shou Li Pan ◽  
Qiang Zhou
Keyword(s):  
Drag Coefficient ◽  
Structure Design ◽  
Cavitation Number ◽  
Multiphase Model ◽  
Surface Moisture ◽  
Bernoulli’S Equation ◽  
Military Applications ◽  
Projectile Technology ◽  
Underwater Projectile ◽  
The Military

Based on the multiphase model of FLUENT 6.3,a underwater projectile cavitation model is established for a new designed underwater projectile which have a disc cavitator.Then the cavitation number influence on cavitation form is concerned and contrast with the empirical formula of cavitation form.The conclusion is：with the increase of cavitation number,the drag coefficient will increase non-linear;the cavitation slenderness radio is greater,the drag coefficient is smaller. Supercavitation phenomenon is that when a object moves in water and it’s speed increases constantly, according to Bernoulli's equation, this will make the hydrostatic pressure that it bears drop. And when the pressure down to the vaporization pressure of water at that temperature, the surface moisture of the object will change into steam, form bubbles and wrap it. Due to the density of water and steam has magnitude deviation, the viscous resistance acting on the underwater moving object will reduce greatly, that can make the performance of underwater weapon enhance markedly. In the military applications, there are represented by Russia, the torpedo of “snowstorm” used the ventilation supercavitation theory and, represented by USA, the “20mm Supercavitation projectile” used the nature supercavitation theory. Facing the daily intelligentized contrail guided torpedo and mine, the small caliber supercavitation projectile technology has provided a new method for the short-range defense of surface vessel. As the nature supercavition projectile is a kind of uncontrolled, unpowered underwater weapon, the formation and stability of cavitation are more significative for performing the properties of projectile. The paper has done same simulate calculation for a new designed subcaliber supercavitation projectile, focused on the cavitation morphology and drag reduction ability under several different projectile velocity circumstance. This research can provide same basis for reasonable structure design of new projectiles.

Resistance Characteristics of Underwater Supercavity

2014 ◽  
Vol 889-890 ◽  
pp. 336-340
Author(s):  
De Xin Zhang ◽  
Gang Liu ◽  
Jian Ming Guo ◽  
Wen Liang Yang ◽  
Zhen Gui Zhao
Keyword(s):  
Multiphase Flow ◽  
Drag Reduction ◽  
Drag Coefficient ◽  
High Speed ◽  
Cavitation Number ◽  
Homogeneous Equilibrium ◽  
Fluent Software ◽  
Natural Formation ◽  
Underwater Projectile ◽  
Reduction Characteristics

This paper based on the Homogeneous equilibrium multiphase flow theory.By using FLUENT software the high-speed underwater projectile resistance characteristics were studied.Analyzed the influence of cavitator diameter and Cavitation number on drag reduction characteristics of the projectile,and compared with the empirical formula.The results showed that the larger the diameter of cavitation,the easier supercavitation natural formation,but the drag coefficient be greater.

Military Applications of Adaptive Training Technology

2008 ◽  
pp. 304-347 ◽  
Author(s):  
James E. McCarthy
Keyword(s):  
Case Studies ◽  
Interactive Multimedia ◽  
Intelligent Tutoring ◽  
Technology Enhanced Learning ◽  
Multimedia Instruction ◽  
Comprehensive Review ◽  
Adaptive Training ◽  
Military Applications ◽  
The Military ◽  
Enhanced Learning

This chapter provides an overview of the use of adaptive training technology within the military domain. Throughout the chapter, we will discuss the use of intelligent tutoring, adaptive interactive multimedia instruction, and their combination to form closed-loop adaptive training. Frequently, the discussion of a particular approach will be illustrated with one or more case-studies. Moreover, we will explore impediments to widespread adoption of these interventions throughout the military, methods to overcome these impediments, and the migration of this technology into other domains. We will conclude by summarizing trends that are likely to characterize on-going development. Rather than providing a comprehensive review of technology-enhanced learning in the military, which is likely to be outdated before it is published, the author hopes that this illustrative review will open new avenues of thought for researchers, developers, and purchasers of these systems.

The Optimum Design of a Cavitator for High-Speed Axisymmetric Bodies in Partially Cavitating Flows

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
I. Rashidi ◽  
Mo. Passandideh-Fard ◽  
Ma. Pasandideh-Fard
Keyword(s):  
Boundary Element Method ◽  
Numerical Simulations ◽  
Drag Coefficient ◽  
Boundary Element ◽  
Cavitation Number ◽  
The Body ◽  
Total Drag ◽  
Conical Section ◽  
Disk Cavitator ◽  
Element Method

In this paper, the partially cavitating flow over an axisymmetric projectile is studied in order to obtain the optimum cavitator such that, at a given cavitation number, the total drag coefficient of the projectile is minimum. For this purpose, the boundary element method and numerical simulations are used. A large number of cavitator profiles are produced using a parabolic expression with three geometric parameters. The potential flow around these cavitators is then solved using the boundary element method. In order to examine the optimization results, several cavitators with a total drag coefficient close to that of the optimum cavitators are also numerically simulated. Eventually, the optimum cavitator is selected using both the boundary element method and numerical simulations. The effects of the body radius and the length of the conical section of the projectile on the shape of the optimized cavitator are also investigated. The results show that for all cavitation numbers, the cavitator that creates a cavity covering the entire conical section of the projectile with a minimum total drag coefficient is optimal. It can be seen that increasing the cavitation number causes the optimum cavitator to approach the disk cavitator. The results also show that at a fixed cavitation number, the increase in both the radius and length of the conical section causes the cavitator shape to approach that of the disk cavitator.

scholarly journals Adaptation of a Small Commercial Fan Jet Trainer for Military Applications

1990 ◽  
Author(s):  
D. I. Boyd
Keyword(s):  
Field Experience ◽  
Development Program ◽  
Test Facility ◽  
Special Test ◽  
Design Features ◽  
Reliable Service ◽  
Military Applications ◽  
History Of ◽  
The Military ◽  
Military Combat

The JTI5D-4 engine is a successful small fan jet with a history of reliable service in fast, economical executive jet aircraft. This paper describes the unique design features which were necessary to convert it to the military combat trainer role, together with the associated development program. It includes details of a special test facility constructed to simulate aerobatic flight conditions, and discusses some aspects of field experience in a single engine trainer application.

scholarly journals Modified Energy Efficient with ACO Routing Protocol for MANET

2021 ◽  
Vol 12 (2) ◽  
pp. 1739-1745
Author(s):  
Uppalapati Srilakshmi, Et. al.
Keyword(s):  
Routing Protocol ◽  
Energy Efficient ◽  
Ad Hoc ◽  
Mobile Ad Hoc Network ◽  
Path Selection ◽  
Delivery Ratio ◽  
Military Applications ◽  
Optimum Path ◽  
Mobile Ad Hoc ◽  
The Military

Due to the specific design of the network upon the requirements of the demands as well as the situation at which the setting up of a physical network is impossible, a significant role is played by mobile ad-hoc network (MANET) in the applications of military. Various critical tasks like robust & dynamic military workstations, devices as well as smaller sub-networks within the battle field are handled by the presented network type controls the infrastructure less communication. A highly demand of the efficient routing protocol’s design is existing which ensures safety as well as reliability to transmit the extremely vulnerable as well as the secret military data within the defense networks. The designing of an energy efficient layer routing protocol within the network on behalf of the military applications is done in this method and the simulation is done with the help of a novel cross layer approach of design for increasing the reliability as well as the lifetime of the network. However, the optimum path selection is not allowed by PDO-AODV technique. Therefore, a novel ACO-DAEE (Ant colony optimization with delay aware energy efficient) to select an optimum path as well as to mitigate the delay time within the network system is proposed. Maintaining the optimum paths within the network while transmitting the data effectively is the major objective. With respect to packet delivery ratio, end to end delay, and throughput, it is indicated by the simulation outputs that the performance of ACO-ADEE is quite good. The efficiency of this technique is verified in the simulation outcomes using NS2 software.

scholarly journals An Intelligent Gain based Ant Colony Optimisation Method for Path Planning of Unmanned Ground Vehicles

2019 ◽  
Vol 69 (2) ◽  
pp. 167-172 ◽  
Author(s):  
Sangeetha Viswanathan ◽  
K. S. Ravichandran ◽  
Anand M. Tapas ◽  
Sellammal Shekhar
Keyword(s):  
Path Planning ◽  
Optimal Path ◽  
Computation Time ◽  
Ant Colony ◽  
Ant Colony Optimisation ◽  
Ground Vehicles ◽  
Optimal Path Planning ◽  
Military Applications ◽  
The Military ◽  
Reduction Cost

 In many of the military applications, path planning is one of the crucial decision-making strategies in an unmanned autonomous system. Many intelligent approaches to pathfinding and generation have been derived in the past decade. Energy reduction (cost and time) during pathfinding is a herculean task. Optimal path planning not only means the shortest path but also finding one in the minimised cost and time. In this paper, an intelligent gain based ant colony optimisation and gain based green-ant (GG-Ant) have been proposed with an efficient path and least computation time than the recent state-of-the-art intelligent techniques. Simulation has been done under different conditions and results outperform the existing ant colony optimisation (ACO) and green-ant techniques with respect to the computation time and path length.

scholarly journals Cavitation Number As a Function of Disk Cavitator Radius: A Numerical Analysis of Natural Supercavitation

2019 ◽  
Author(s):  
Reid Prichard ◽  
Wayne Strasser ◽  
Thomas Eldredge
Keyword(s):  
Numerical Analysis ◽  
Drag Coefficient ◽  
Skin Friction ◽  
Cavitation Number ◽  
Maximum Speed ◽  
Friction Drag ◽  
Disk Cavitator ◽  
Density Of Water

Abstract Due to the greater viscosity and density of water compared to air, the maximum speed of underwater travel is severely limited compared to other methods of transportation. However, a technology called supercavitation — which uses a disk-shaped cavitator to envelop a vehicle in a bubble of steam — promises to greatly decrease skin friction drag. While a large cavitator enables the occurrence of supercavitation at low velocities, it adds substantial drag at higher speeds. Based on CFD results, we propose a new relationship between drag coefficient and disk cavitator radius, and we predict the optimum cavitator radius for a particular torpedo design.

scholarly journals Urânio Exaurido: Origem, aplicações e suas consequências

2020 ◽  
pp. 219-240
Author(s):  
PF Poveda
Keyword(s):  
Heavy Metals ◽  
Reproductive System ◽  
Chronic Exposure ◽  
Nuclear Reactors ◽  
Natural Uranium ◽  
Depleted Uranium ◽  
Laboratory Studies ◽  
Suitable Material ◽  
Military Applications ◽  
The Military

Depleted uranium is almost entirely composed of the 238U isotope (uranium-238) and is a residue of the enrichment or reprocessing process of natural uranium to obtain the 235U isotope (Uranium-235), used in fission in nuclear reactors and bombs. Its high density (19,050 kg / m³), 67% higher than that of lead, makes depleted uranium a suitable material for various civil and military applications. In the civilian field it is used mainly as ballast in aircraft, boats and submarines and as a shield against radiation. In the military, it is used in projectiles (called "penetrators"), physical armor and artillery pieces in general. Such uses are controversial. Although it is less toxic than other heavy metals (such as arsenic and mercury) and weakly radioactive, due to its long half-life of about 4.5 billion years, it emits the equivalent of about 60% of the radiation emanating from the natural uranium, it has been proven, from several laboratory studies, that it is toxic to mammals, attacks the reproductive system and the development of the fetus, causing reduced fertility, abortions and deformities in newborns. Cytological tests show that, with chronic exposure, DU is leukogenic, mutagenic and also neurotoxic.

scholarly journals The strategic paradox of autonomous weapons

2018 ◽  
Author(s):  
Marko Kovic
Keyword(s):  
Negative Impact ◽  
Positive Impact ◽  
Humanitarian Law ◽  
Security Risk ◽  
Security Risks ◽  
Autonomous Weapons ◽  
Military Applications ◽  
Chain Of Command ◽  
Potential Impact ◽  
The Military

Progress in artificial intelligence makes the technology increasingly relevant to military applications. In particular, autonomous weapons could be of great military use: Autonomous weapons could achieve goals more effectively and more efficiently than humans or human-operated weapons. In this policy brief, the potential impact of implementing autonomous weapons on the behavior and decision-making of the military is discussed. The most probable positive impact, greater adherence to humanitarian law on the battlefield, is outweighed by the most probable negative impact, a disruption of the military chain of command and the security risks that follow from that disruption. This creates a strategic paradox: Even though autonomous weapons could help the military achieve goals more effectively and more efficiently, autonomous weapons would strategically undermine the military by disrupting the chain of command and by creating a great security risk.

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