Misplaced Pages

#839160

75-405: A bomb is an explosive weapon that uses the exothermic reaction of an explosive material to provide an extremely sudden and violent release of energy . Detonations inflict damage principally through ground- and atmosphere-transmitted mechanical stress , the impact and penetration of pressure-driven projectiles, pressure damage, and explosion-generated effects. Bombs have been utilized since

150-650: A Jurchen Jin army against a Chinese Song city. The term for this explosive bomb seems to have been coined the " thunder crash bomb " during a Jin dynasty (1115–1234) naval battle in 1231 against the Mongols . The History of Jin (金史) (compiled by 1345) states that in 1232, as the Mongol general Subutai (1176–1248) descended on the Jin stronghold of Kaifeng , the defenders had a " thunder crash bomb " which "consisted of gunpowder put into an iron container ... then when

225-404: A blasting cap containing a more sensitive primary explosive . A thermobaric bomb is a type of explosive that utilizes oxygen from the surrounding air to generate an intense, high-temperature explosion, and in practice the blast wave typically produced by such a weapon is of a significantly longer duration than that produced by a conventional condensed explosive. The fuel-air bomb is one of

300-486: A supersonic jet's flyby (directly underneath the meteor's path) and as a detonation wave , with the circular shock wave centred at the meteor explosion, causing multiple instances of broken glass in the city of Chelyabinsk and neighbouring areas (pictured). In the examples below, the shock wave is controlled, produced by (ex. airfoil) or in the interior of a technological device, like a turbine . The wave disk engine (also named "Radial Internal Combustion Wave Rotor")

375-580: A ban on exploding ammunition under customary international humanitarian law binding on all States. The 1997 Mine Ban Treaty and the 2008 Convention on Cluster Munitions also prohibit types of explosive weapons, anti-personnel landmines and cluster munitions , for states parties to these treaties . The Secretary-General of the United Nations has expressed increasing concern at "the humanitarian impact of explosive weapons, in particular when used in densely populated areas." The President of

450-593: A bomb exploding in a transport network often damages, and is sometimes mainly intended to damage, the network itself. This applies to railways , bridges , runways , and ports , and, to a lesser extent (depending on circumstances), to roads. In the case of suicide bombing , the bomb is often carried by the attacker on their body, or in a vehicle driven to the target. The Blue Peacock nuclear mines, which were also termed "bombs", were planned to be positioned during wartime and be constructed such that, if disturbed, they would explode within ten seconds. The explosion of

525-477: A bomb may be triggered by a detonator or a fuse . Detonators are triggered by clocks , remote controls like cell phones or some kind of sensor, such as pressure (altitude), radar , vibration or contact. Detonators vary in ways they work, they can be electrical, fire fuze or blast initiated detonators and others, In forensic science , the point of detonation of a bomb is referred to as its blast seat, seat of explosion, blast hole or epicenter . Depending on

600-499: A combination of negative shock wave effects and extreme temperature to incinerate objects within the blast radius. Fragmentation is produced by the acceleration of shattered pieces of bomb casing and adjacent physical objects. The use of fragmentation in bombs dates to the 14th century, and appears in the Ming Dynasty text Huolongjing . The fragmentation bombs were filled with iron pellets and pieces of broken porcelain. Once

675-407: A comparatively low explosive yield to scatter harmful material over a wide area. Most commonly associated with radiological or chemical materials, dirty bombs seek to kill or injure and then to deny access to a contaminated area until a thorough clean-up can be accomplished. In the case of urban settings, this clean-up may take extensive time, rendering the contaminated zone virtually uninhabitable in

750-407: A component vector analysis of the flow; doing so allows for the treatment of the flow in an orthogonal direction to the oblique shock as a normal shock. When an oblique shock is likely to form at an angle which cannot remain on the surface, a nonlinear phenomenon arises where the shock wave will form a continuous pattern around the body. These are termed bow shocks . In these cases, the 1d flow model

825-642: A configuration in which the rapidly moving material down the chute impinges on an obstruction wall erected perpendicular at the end of a long and steep channel. Impact leads to a sudden change in the flow regime from a fast moving supercritical thin layer to a stagnant thick heap. This flow configuration is particularly interesting because it is analogous to some hydraulic and aerodynamic situations associated with flow regime changes from supercritical to subcritical flows. Astrophysical environments feature many different types of shock waves. Some common examples are supernovae shock waves or blast waves travelling through

SECTION 10

#1732765502840

900-702: A distance (not coincidentally, since explosions create shock waves). Analogous phenomena are known outside fluid mechanics. For example, charged particles accelerated beyond the speed of light in a refractive medium (such as water, where the speed of light is less than that in a vacuum ) create visible shock effects, a phenomenon known as Cherenkov radiation . Below are a number of examples of shock waves, broadly grouped with similar shock phenomena: Shock waves can also occur in rapid flows of dense granular materials down inclined channels or slopes. Strong shocks in rapid dense granular flows can be studied theoretically and analyzed to compare with experimental data. Consider

975-411: A high burst pressure to be useful as a bomb. A high explosive bomb is one that employs a process called " detonation " to rapidly go from an initially high energy molecule to a very low energy molecule. Detonation is distinct from deflagration in that the chemical reaction propagates faster than the speed of sound (often many times faster) in an intense shock wave. Therefore, the pressure wave produced by

1050-444: A high explosive is not significantly increased by confinement as detonation occurs so quickly that the resulting plasma does not expand much before all the explosive material has reacted. This has led to the development of plastic explosive . A casing is still employed in some high explosive bombs, but with the purpose of fragmentation . Most high explosive bombs consist of an insensitive secondary explosive that must be detonated with

1125-402: A loud "crack" or "snap" noise. Over longer distances, a shock wave can change from a nonlinear wave into a linear wave, degenerating into a conventional sound wave as it heats the air and loses energy. The sound wave is heard as the familiar "thud" or "thump" of a sonic boom , commonly created by the supersonic flight of aircraft. The shock wave is one of several different ways in which a gas in

1200-574: A major military feature, and a number of novel delivery methods were introduced. These included Barnes Wallis 's bouncing bomb , designed to bounce across water, avoiding torpedo nets and other underwater defenses, until it reached a dam , ship , or other destination, where it would sink and explode. By the end of the war, planes such as the allied forces' Avro Lancaster were delivering with 50 yd (46 m) accuracy from 20,000 ft (6,100 m), ten ton earthquake bombs (also invented by Barnes Wallis) named " Grand Slam ", which, unusually for

1275-403: A medium, but is characterized by an abrupt, nearly discontinuous, change in pressure , temperature , and density of the medium. For the purpose of comparison, in supersonic flows, additional increased expansion may be achieved through an expansion fan , also known as a Prandtl–Meyer expansion fan . The accompanying expansion wave may approach and eventually collide and recombine with

1350-401: A mixture of an oxidizing salt, such as potassium nitrate (saltpeter), with solid fuel, such as charcoal or aluminium powder. These compositions deflagrate upon ignition, producing hot gas. Under normal circumstances, this deflagration occurs too slowly to produce a significant pressure wave; low explosives, therefore, must generally be used in large quantities or confined in a container with

1425-403: A partnership of NGOs, is calling for immediate action to prevent human suffering from the use of explosive weapons in populated areas. Shock wave In physics, a shock wave (also spelled shockwave ), or shock , is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through

1500-523: A range of offensive weaponry. For instance, in recent asymmetric conflicts, homemade bombs called " improvised explosive devices " (IEDs) have been employed by irregular forces to great effectiveness. The word comes from the Latin bombus , which in turn comes from the Greek βόμβος romanized bombos , an onomatopoetic term meaning 'booming', 'buzzing'. Gunpowder bombs had been mentioned since

1575-424: A shock wave. It is assumed the system is adiabatic (no heat exits or enters the system) and no work is being done. The Rankine–Hugoniot conditions arise from these considerations. Taking into account the established assumptions, in a system where the downstream properties are becoming subsonic: the upstream and downstream flow properties of the fluid are considered isentropic. Since the total amount of energy within

SECTION 20

#1732765502840

1650-407: A significant explosion can occur. Under the right circumstances, rapid consolidation can provoke a chain reaction that can proliferate and intensify by many orders of magnitude within microseconds. The energy released by a nuclear fission bomb may be tens of thousands of times greater than a chemical bomb of the same mass. A thermonuclear weapon is a type of nuclear bomb that releases energy through

1725-631: A single pylon. Some bombs are equipped with a parachute , such as the World War II "parafrag" (an 11 kg (24 lb) fragmentation bomb), the Vietnam War -era daisy cutters , and the bomblets of some modern cluster bombs . Parachutes slow the bomb's descent, giving the dropping aircraft time to get to a safe distance from the explosion. This is especially important with air-burst nuclear weapons (especially those dropped from slower aircraft or with very high yields), and in situations where

1800-561: A standard design out of standard components and intended to be deployed in a standard explosive device. IEDs are divided into three basic categories by basic size and delivery. Type 76, IEDs are hand-carried parcel or suitcase bombs, type 80, are "suicide vests" worn by a bomber, and type 3 devices are vehicles laden with explosives to act as large-scale stationary or self-propelled bombs, also known as VBIED (vehicle-borne IEDs). Improvised explosive materials are typically unstable and subject to spontaneous, unintentional detonation triggered by

1875-458: A supersonic flow can be compressed. Some other methods are isentropic compressions, including Prandtl –Meyer compressions. The method of compression of a gas results in different temperatures and densities for a given pressure ratio which can be analytically calculated for a non-reacting gas. A shock wave compression results in a loss of total pressure, meaning that it is a less efficient method of compressing gases for some purposes, for instance in

1950-496: A two-ton anchor which was hurled nearly two miles inland to embed itself in the parking lot of the Pan American refinery. To people who are close to a blast incident, such as bomb disposal technicians, soldiers wearing body armor, deminers, or individuals wearing little to no protection, there are four types of blast effects on the human body: overpressure (shock), fragmentation , impact , and heat . Overpressure refers to

2025-469: A wide range of environmental effects, ranging from impact and friction to electrostatic shock. Even subtle motion , change in temperature , or the nearby use of cellphones or radios can trigger an unstable or remote-controlled device. Any interaction with explosive materials or devices by unqualified personnel should be considered a grave and immediate risk of death or dire injury. The safest response to finding an object believed to be an explosive device

2100-459: Is a hypothetical nuclear weapon that does not require a primary fission stage to start a fusion reaction. Antimatter bombs can theoretically be constructed, but antimatter is very costly to produce and hard to store safely. The first air-dropped bombs were used by the Austrians in the 1849 siege of Venice . Two hundred unmanned balloons carried small bombs, although few bombs actually hit

2175-572: Is a kind of pistonless rotary engine that utilizes shock waves to transfer energy between a high-energy fluid to a low-energy fluid, thereby increasing both temperature and pressure of the low-energy fluid. In memristors , under externally-applied electric field, shock waves can be launched across the transition-metal oxides, creating fast and non-volatile resistivity changes. Advanced techniques are needed to capture shock waves and to detect shock waves in both numerical computations and experimental observations. Computational fluid dynamics

2250-481: Is commonly used to obtain the flow field with shock waves. Though shock waves are sharp discontinuities, in numerical solutions of fluid flow with discontinuities (shock wave, contact discontinuity or slip line), the shock wave can be smoothed out by low-order numerical method (due to numerical dissipation) or there are spurious oscillations near shock surface by high-order numerical method (due to Gibbs phenomena ). There exist some other discontinuities in fluid flow than

2325-437: Is created by the sudden release of heat caused by an explosion. Military bomb tests have documented temperatures of up to 2,480 °C (4,500 °F). While capable of inflicting severe to catastrophic burns and causing secondary fires, thermal wave effects are considered very limited in range compared to shock and fragmentation. This rule has been challenged, however, by military development of thermobaric weapons , which employ

Bomb - Misplaced Pages Continue

2400-408: Is not valid and further analysis is needed to predict the pressure forces which are exerted on the surface. Shock waves can form due to steepening of ordinary waves. The best-known example of this phenomenon is ocean waves that form breakers on the shore. In shallow water, the speed of surface waves is dependent on the depth of the water. An incoming ocean wave has a slightly higher wave speed near

2475-415: Is to get as far away from it as possible. Atomic bombs are based on the theory of nuclear fission , that when a large atom splits, it releases a massive amount of energy. Thermonuclear weapons , (colloquially known as "hydrogen bombs") use the energy from an initial fission explosion to create an even more powerful fusion explosion. The term " dirty bomb " refers to a specialized device that relies on

2550-851: The International Committee of the Red Cross (ICRC), Jakob Kellenberger has noted that "ICRC’s key operations in 2009 – in the Gaza Strip and in Sri Lanka – provided stark illustrations of the potentially devastating humanitarian consequences of military operations conducted in densely populated areas, especially when heavy or highly explosive weapons are used." According to the British NGO Action on Armed Violence (AOAV) , when explosive weapons are used in populated areas (towns, villages, residential neighbourhoods)

2625-541: The United States Air Force 's MOAB (officially Massive Ordnance Air Blast, or more commonly known as the "Mother of All Bombs"). Below is a list of five different types of bombs based on the fundamental explosive mechanism they employ. Relatively small explosions can be produced by pressurizing a container until catastrophic failure such as with a dry ice bomb . Technically, devices that create explosions of this type can not be classified as "bombs" by

2700-577: The "thunder-crash bombs" has been discovered in an underwater shipwreck off the shore of Japan by the Kyushu Okinawa Society for Underwater Archaeology. X-rays by Japanese scientists of the excavated shells confirmed that they contained gunpowder. Explosive shock waves can cause situations such as body displacement (i.e., people being thrown through the air), dismemberment , internal bleeding and ruptured eardrums . Shock waves produced by explosive events have two distinct components,

2775-681: The 11th century starting in East Asia . The term bomb is not usually applied to explosive devices used for civilian purposes such as construction or mining , although the people using the devices may sometimes refer to them as a "bomb". The military use of the term "bomb", or more specifically aerial bomb action, typically refers to airdropped, unpowered explosive weapons most commonly used by air forces and naval aviation . Other military explosive weapons not classified as "bombs" include shells , depth charges (used in water), or land mines . In unconventional warfare , other names can refer to

2850-803: The 11th century. In 1000 AD, a soldier by the name of Tang Fu (唐福) demonstrated a design of gunpowder pots (a proto-bomb which spews fire) and gunpowder caltrops, for which he was richly rewarded. In the same year, Xu Dong wrote that trebuchets used bombs that were like "flying fire", suggesting that they were incendiaries. In the military text Wujing Zongyao of 1044, bombs such as the "ten-thousand fire flying sand magic bomb", "burning heaven fierce fire unstoppable bomb", and "thunderclap bomb" ( pilipao ) were mentioned. However these were soft-shell bombs and did not use metal casings. Bombs made of cast iron shells packed with explosive gunpowder date to 13th century China. Explosive bombs were used in East Asia in 1221, by

2925-465: The Earth's atmosphere. The Tunguska event and the 2013 Russian meteor event are the best documented evidence of the shock wave produced by a massive meteoroid . When the 2013 meteor entered into the Earth's atmosphere with an energy release equivalent to 100 or more kilotons of TNT, dozens of times more powerful than the atomic bomb dropped on Hiroshima , the meteor's shock wave produced damage as in

3000-490: The aircraft releases a bomb at low altitude. A number of modern bombs are also precision-guided munitions , and may be guided after they leave an aircraft by remote control, or by autonomous guidance. Aircraft may also deliver bombs in the form of warheads on guided missiles , such as long-range cruise missiles , which can also be launched from warships . A hand grenade is delivered by being thrown. Grenades can also be projected by other means, such as being launched from

3075-427: The approach of the object. In this description, the shock wave position is defined as the boundary between the zone having no information about the shock-driving event and the zone aware of the shock-driving event, analogous with the light cone described in the theory of special relativity . To produce a shock wave, an object in a given medium (such as air or water) must travel faster than the local speed of sound. In

Bomb - Misplaced Pages Continue

3150-401: The best-known types of thermobaric weapons. Nuclear fission type atomic bombs utilize the energy present in very heavy atomic nuclei, such as U-235 or Pu-239. In order to release this energy rapidly, a certain amount of the fissile material must be very rapidly consolidated while being exposed to a neutron source. If consolidation occurs slowly, repulsive forces drive the material apart before

3225-533: The bomb explodes, the resulting fragments are capable of piercing the skin and blinding enemy soldiers. While conventionally viewed as small metal shards moving at super- supersonic and hypersonic speeds, fragmentation can occur in epic proportions and travel for extensive distances. When the SS Grandcamp exploded in the Texas City Disaster on April 16, 1947, one fragment of that blast was

3300-400: The bright timbre of the instruments. While shock formation by this process does not normally happen to unenclosed sound waves in Earth's atmosphere, it is thought to be one mechanism by which the solar chromosphere and corona are heated, via waves that propagate up from the solar interior. A shock wave may be described as the furthest point upstream of a moving object which "knows" about

3375-449: The case of an aircraft travelling at high subsonic speed, regions of air around the aircraft may be travelling at exactly the speed of sound, so that the sound waves leaving the aircraft pile up on one another, similar to a traffic jam on a motorway. When a shock wave forms, the local air pressure increases and then spreads out sideways. Because of this amplification effect, a shock wave can be very intense, more like an explosion when heard at

3450-868: The city. The first bombing from a fixed-wing aircraft took place in 1911 when the Italians dropped bombs by hand on the Turkish lines in what is now Libya , during the Italo-Turkish War . The first large scale dropping of bombs took place during World War I starting in 1915 with the German Zeppelin airship raids on London , England, and the same war saw the invention of the first heavy bombers . One Zeppelin raid on 8 September 1915 dropped 4,000 lb (1,800 kg) of high explosives and incendiary bombs, including one bomb that weighed 600 lb (270 kg). During World War II bombing became

3525-608: The combination of fission and fusion of the light atomic nuclei of deuterium and tritium. With this type of bomb, a thermonuclear detonation is triggered by the detonation of a fission type nuclear bomb contained within a material containing high concentrations of deuterium and tritium. Weapon yield is typically increased with a tamper that increases the duration and intensity of the reaction through inertial confinement and neutron reflection. Nuclear fusion bombs can have arbitrarily high yields making them hundreds or thousands of times more powerful than nuclear fission. A pure fusion weapon

3600-427: The control surfaces that bound this volume parallel to the shock wave (with one surface on the pre-shock side of the fluid medium and one on the post-shock side). The two surfaces are separated by a very small depth such that the shock itself is entirely contained between them. At such control surfaces, momentum, mass flux and energy are constant; within combustion, detonations can be modelled as heat introduction across

3675-409: The crest of each wave than near the troughs between waves, because the wave height is not infinitesimal compared to the depth of the water. The crests overtake the troughs until the leading edge of the wave forms a vertical face and spills over to form a turbulent shock (a breaker) that dissipates the wave's energy as sound and heat. Similar phenomena affect strong sound waves in gas or plasma, due to

3750-433: The definition presented at the top of this article. However, the explosions created by these devices can cause property damage, injury, or death. Flammable liquids, gasses and gas mixtures dispersed in these explosions may also ignite if exposed to a spark or flame. The simplest and oldest bombs store energy in the form of a low explosive . Black powder is an example of a low explosive. Low explosives typically consist of

3825-401: The dependence of the sound speed on temperature and pressure. Strong waves heat the medium near each pressure front, due to adiabatic compression of the air itself, so that high pressure fronts outrun the corresponding pressure troughs. There is a theory that the sound pressure levels in brass instruments such as the trombone become high enough for steepening to occur, forming an essential part of

SECTION 50

#1732765502840

3900-448: The explosive fireball as well as incendiary agents projected onto the body. Personal protective equipment, such as a bomb suit or demining ensemble, as well as helmets, visors and foot protection, can dramatically reduce the four effects, depending upon the charge, proximity and other variables. Experts commonly distinguish between civilian and military bombs. The latter are almost always mass-produced weapons, developed and constructed to

3975-462: The fuse was lit (and the projectile shot off) there was a great explosion the noise whereof was like thunder, audible for more than thirty miles, and the vegetation was scorched and blasted by the heat over an area of more than half a mou . When hit, even iron armour was quite pierced through." The Song Dynasty (960–1279) official Li Zengbo wrote in 1257 that arsenals should have several hundred thousand iron bomb shells available and that when he

4050-585: The general rules of international humanitarian law governing the conduct of hostilities apply to the use of all types of explosive weapons as means or methods of warfare. Taken in combination, Amended Protocol II and Protocol V to the United Nations Convention on Certain Conventional Weapons establish a responsibility on the users of explosive weapons to record and retain information on their use of such weapons (including

4125-451: The generic term bomb . Certain types of explosive weapons may be categorized as light weapons (e.g. grenades , grenade launchers , rocket launchers , anti-tank guided missile launchers , man-portable air-defense systems , and mortars of calibers of less than 100 mm). Many explosive weapons, such as aerial bombs , multiple rocket launchers , artillery , and larger mortars, are categorized as heavy weapons. In armed conflict,

4200-447: The insufficient aspects of numerical and experimental tools lead to two important problems in practices: (1) some shock waves can not be detected or their positions are detected wrong, (2) some flow structures which are not shock waves are wrongly detected to be shock waves. In fact, correct capturing and detection of shock waves are important since shock waves have the following influences: (1) causing loss of total pressure, which may be

4275-400: The intake of a scramjet . The appearance of pressure-drag on supersonic aircraft is mostly due to the effect of shock compression on the flow. In elementary fluid mechanics utilizing ideal gases , a shock wave is treated as a discontinuity where entropy increases abruptly as the shock passes. Since no fluid flow is discontinuous, a control volume is established around the shock wave, with

4350-571: The interim. The power of large bombs is typically measured in kilotons (kt) or megatons of TNT (Mt) . The most powerful bombs ever used in combat were the two atomic bombs dropped by the United States to attack Hiroshima and Nagasaki , and the most powerful ever tested was the Tsar Bomba . The most powerful non-nuclear bomb is Russian " Father of All Bombs " (officially Aviation Thermobaric Bomb of Increased Power (ATBIP)) followed by

4425-427: The internal organs. When the overpressure wave impacts the body it can induce violent levels of blast-induced acceleration. Resulting injuries may range from minor to unsurvivable. Immediately following this initial acceleration, deceleration injuries can occur when a person impacts directly against a rigid surface or obstacle after being set in motion by the force of the blast. Finally, injury and fatality can result from

4500-402: The interstellar medium, the bow shock caused by the Earth's magnetic field colliding with the solar wind and shock waves caused by galaxies colliding with each other. Another interesting type of shock in astrophysics is the quasi-steady reverse shock or termination shock that terminates the ultra relativistic wind from young pulsars . Shock waves are generated by meteoroids when they enter

4575-436: The location of use and the type and quantity of weapons used), to provide such information to parties in control of territory that may be affected by UXO , and to assist with the removal of this threat. Certain types of explosive weapons have been subject to prohibition in international treaties. The Saint Petersburg Declaration of 1868 prohibits the use of certain explosive rifle projectiles. This prohibition has evolved into

SECTION 60

#1732765502840

4650-437: The matter's properties manifests itself as a decrease in the energy which can be extracted as work, and as a drag force on supersonic objects ; shock waves are strongly irreversible processes . Shock waves can be: Some other terms: The abruptness of change in the features of the medium, that characterize shock waves, can be viewed as a phase transition : the pressure–time diagram of a supersonic object propagating shows how

4725-462: The muzzle of a rifle (as in the rifle grenade ), using a grenade launcher (such as the M203 ), or by attaching a rocket to the explosive grenade (as in a rocket-propelled grenade (RPG)). A bomb may also be positioned in advance and concealed. A bomb destroying a rail track just before a train arrives will usually cause the train to derail . In addition to the damage to vehicles and people,

4800-450: The overwhelming majority (91% in 2012) of direct casualties are civilians . Action on Armed Violence has also charted a dramatic rise in the use of suicide bombing and improvised explosive devices globally. Their data showed the number of civilians killed or injured by car and suicide bombs and other improvised explosive devices rising by 70 percent in the three years to 2013. The International Network on Explosive Weapons (INEW) ,

4875-482: The positive and negative wave. The positive wave shoves outward from the point of detonation, followed by the trailing vacuum space "sucking back" towards the point of origin as the shock bubble collapses. The greatest defense against shock injuries is distance from the source of shock. As a point of reference, the overpressure at the Oklahoma City bombing was estimated in the range of 28 MPa . A thermal wave

4950-443: The shock wave, creating a process of destructive interference. The sonic boom associated with the passage of a supersonic aircraft is a type of sound wave produced by constructive interference . Unlike solitons (another kind of nonlinear wave), the energy and speed of a shock wave alone dissipates relatively quickly with distance. When a shock wave passes through matter, energy is preserved but entropy increases. This change in

5025-458: The shock wave. The slip surface (3D) or slip line (2D) is a plane across which the tangent velocity is discontinuous, while pressure and normal velocity are continuous. Across the contact discontinuity, the pressure and velocity are continuous and the density is discontinuous. A strong expansion wave or shear layer may also contain high gradient regions which appear to be a discontinuity. Some common features of these flow structures and shock waves and

5100-419: The sudden and drastic rise in ambient pressure that can damage the internal organs, possibly leading to permanent damage or death. Fragmentation can also include sand, debris and vegetation from the area surrounding the blast source. This is very common in anti-personnel mine blasts. The projection of materials poses a potentially lethal threat caused by cuts in soft tissues, as well as infections, and injuries to

5175-404: The surrounding air. At the region where this occurs, sound waves travelling against the flow reach a point where they cannot travel any further upstream and the pressure progressively builds in that region; a high-pressure shock wave rapidly forms. Shock waves are not conventional sound waves; a shock wave takes the form of a very sharp change in the gas properties. Shock waves in air are heard as

5250-412: The system is constant, the stagnation enthalpy remains constant over both regions. However, entropy is increasing; this must be accounted for by a drop in stagnation pressure of the downstream fluid. When analyzing shock waves in a flow field, which are still attached to the body, the shock wave which is deviating at some arbitrary angle from the flow direction is termed oblique shock. These shocks require

5325-438: The thickness of shock waves in air have resulted in values around 200 nm (about 10 in), which is on the same order of magnitude as the mean free path of gas molecules. In reference to the continuum, this implies the shock wave can be treated as either a line or a plane if the flow field is two-dimensional or three-dimensional, respectively. Shock waves are formed when a pressure front moves at supersonic speeds and pushes on

5400-515: The time, were delivered from high altitude in order to gain high speed, and would, upon impact, penetrate and explode deep underground (" camouflet "), causing massive caverns or craters, and affecting targets too large or difficult to be affected by other types of bomb. Modern military bomber aircraft are designed around a large-capacity internal bomb bay , while fighter-bombers usually carry bombs externally on pylons or bomb racks or on multiple ejection racks, which enable mounting several bombs on

5475-462: The transition induced by a shock wave is analogous to a dynamic phase transition . When an object (or disturbance) moves faster than the information can propagate into the surrounding fluid, then the fluid near the disturbance cannot react or "get out of the way" before the disturbance arrives. In a shock wave the properties of the fluid ( density , pressure , temperature , flow velocity , Mach number ) change almost instantaneously. Measurements of

5550-840: The type, quantity and placement of explosives, the blast seat may be either spread out or concentrated (i.e., an explosion crater ). Other types of explosions , such as dust or vapor explosions, do not cause craters or even have definitive blast seats. Explosive weapon In the common practice of states , explosive weapons are generally the preserve of the military , for use in situations of armed conflict , and are rarely used for purposes of domestic policing . When explosive weapons fail to function as designed they are often left as unexploded ordnance (UXO). Explosive weapons may be subdivided by their method of manufacture into explosive ordnance and improvised explosive devices (IEDs). Certain types of explosive ordnance and many improvised explosive devices are sometimes referred to under

5625-631: Was in Jingzhou , about one to two thousand were produced each month for dispatch of ten to twenty thousand at a time to Xiangyang and Yingzhou. The Ming Dynasty text Huolongjing describes the use of poisonous gunpowder bombs, including the "wind-and-dust" bomb. During the Mongol invasions of Japan , the Mongols used the explosive "thunder-crash bombs" against the Japanese. Archaeological evidence of

#839160