A
shock wave (also called
shock front or simply "
shock") is a type of propagating disturbance. Like an ordinary
waveA wave is a disturbance that propagates through space and time, usually with transference of energy. A mechanical wave is a wave that propagates or travels through a medium due to the restoring forces it produces upon deformation. There also exist waves capable of traveling through a vacuum,...
, it carries energy and can propagate through a medium (
solidMatter is generally found in three different forms: solid, liquid, and gas . The solid state of matter is characterized by a distinct structural rigidity and resistance to deformation . Most solids have high values both of Young's modulus and of the shear modulus of elasticity...
,
liquidLiquid is one of the principal states of matter. A liquid is a fluid that has the particles loose and can freely form a distinct surface at the boundaries of its bulk material. The surface is a free surface where the liquid is not constrained by a container....
or
gasThis page is about the physical properties of gas as a state of matter. For the uses of gases, and other meanings, see Gas .A gas is one of four states of matter. Near absolute zero, a substance exists as a solid...
) or in some cases in the absence of a material medium, through a
fieldIn physics, a field is a physical quantity associated to each point of spacetime. A field can be classified as a scalar field, a vector field, or a tensor field, according to whether the value of the field at each point is a scalar, a vector, or, more generally, a tensor, respectively...
such as the
electromagnetic fieldThe electromagnetic field is a physical field produced by electrically charged objects. It affects the behavior of charged objects in the vicinity of the field. Light is the electromagnetic field in a certain frequency range...
. Shock waves are characterized by an abrupt, nearly discontinuous change in the characteristics of the medium. Across a shock there is always an extremely rapid rise in
pressurePressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
,
temperatureIn physics, temperature is a physical property of a system that underlies the common notions of hot and cold; something that feels hotter generally has the higher temperature. Temperature is one of the principal parameters of thermodynamics...
and
densityThe density of a material is defined as its mass per unit volume. The symbol of density is ρ .- Formula :Mathematically:where: is the density, is the mass, is the volume....
of the flow. In supersonic flows, expansion is achieved through an expansion fan. A shock wave travels through most media at a higher speed than an ordinary wave.
Unlike
solitonIn mathematics and physics, a soliton is a self-reinforcing solitary wave that maintains its shape while it travels at constant speed. Solitons are caused by a cancellation of nonlinear and dispersive effects in the medium. "Dispersive effects" refer to dispersion relations between the frequency...
s (another kind of nonlinear wave), the energy of a shock wave dissipates relatively quickly with distance. Also, the accompanying expansion wave approaches and eventually merges with the shock wave, partially cancelling it out. Thus the
sonic boomThe term sonic boom is commonly used to refer to the shocks caused by the supersonic flight of an aircraft. Sonic booms generate enormous amounts of sound energy, sounding much like an explosion...
associated with the passage of a supersonic aircraft is the sound wave resulting from the degradation and merging of the shock wave and the expansion wave produced by the aircraft.
When a shock wave passes through matter, the total energy is preserved but the energy which can be extracted as work decreases and entropy increases. This, for example, creates additional
dragWave drag is an aerodynamics term that refers to a sudden and very powerful form of drag that appears on aircraft and blade tips moving at high-subsonic and supersonic speeds.- Overview :...
force on aircraft with shocks.
Terminology
Shock waves can be:
- Normal
A surface normal, or simply normal, to a flat surface is a vector which is perpendicular to that surface. A normal to a non-flat surface at a point P on the surface is a vector perpendicular to the tangent plane to that surface at P. The word "normal" is also used as an adjective: a line normal to...
: at 90° (perpendicular) to the shock medium's flow direction.
- Oblique
An oblique shock wave, unlike a normal shock, is inclined with respect to the incident upstream flow direction. It will occur when a supersonic flow encounters a corner that effectively turns the flow into itself and compresses. The upstream streamlines are uniformly deflected after the shock wave...
: at an angle to the direction of flow.
- Bow
A bow shock, also called a detached shock, is a curved, stationary shock wave that is found in supersonic flow past a finite body. Unlike an oblique shock, the bow shock is not necessarily attached to the tip of the body. Oblique shock angles are limited in formation based on the corner angle and...
: Occurs upstream of the front (bowThe bow is a nautical term that refers to the forward part of the hull of a ship or boat, the point that is most forward when the vessel is underway. Both of the adjectives fore and forward mean towards the bow...
) of a blunt object when the upstream velocity exceeds Mach 1.
Some other terms
- Shock Front: an alternative name for the shock wave itself
- Contact Front: in a shock wave caused by a driver gas (for example the "impact" of a high explosive on the surrounding air), the boundary between the driver (explosive products) and the driven (air) gases. The Contact Front trails the Shock Front.
In supersonic flows
When an object (or disturbance) moves faster than the information about it can be propagated into the surrounding fluid, 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 (
densityThe density of a material is defined as its mass per unit volume. The symbol of density is ρ .- Formula :Mathematically:where: is the density, is the mass, is the volume....
,
pressurePressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
,
temperatureIn physics, temperature is a physical property of a system that underlies the common notions of hot and cold; something that feels hotter generally has the higher temperature. Temperature is one of the principal parameters of thermodynamics...
,
velocityIn physics, velocity is the rate of change of position. It is a vector physical quantity; both speed and direction are required to define it. In the SI system, it is measured in meters per second: or ms-1. The scalar absolute value of velocity is speed...
,
Mach numberMach number is the speed of an object moving through air, or any fluid substance, divided by the speed of sound as it is in that substance...
) change almost instantaneously. Measurements of the thickness of shock waves have resulted in values approximately one
order of magnitudeAn order of magnitude is the class of scale or magnitude of any amount, where each class contains values of a fixed ratio to the class preceding it. In its most common usage, the amount being scaled is 10 and the scale is the exponent being applied to this amount...
greater than the
mean free pathIn physics the mean free path of a particle is the average distance covered by a particle between successive impacts.. Alternatively, it is the distance at which the intensity of particles drops by 1/e.-Derivation:...
of the gas investigated.
Shock waves form when the speed of a gas changes by more than the
speed of soundSound is a vibration that travels through an elastic medium as a wave. The speed of sound describes how far this wave travels in a given amount of time. In dry air at , the speed of sound is . This equates to , or about one mile in five seconds...
. At the region where this occurs sound waves traveling against the flow reach a point where they cannot travel any further upstream and the pressure progressively builds in that region, and 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 on the order of a few
mean free pathIn physics the mean free path of a particle is the average distance covered by a particle between successive impacts.. Alternatively, it is the distance at which the intensity of particles drops by 1/e.-Derivation:...
s (roughly micro-meters at atmospheric conditions) in thickness. Shock waves in air are heard as 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 boomThe term sonic boom is commonly used to refer to the shocks caused by the supersonic flight of an aircraft. Sonic booms generate enormous amounts of sound energy, sounding much like an explosion...
, commonly created by the
supersonicThe term supersonic is used to define a speed that is over the speed of sound . In dry air at 20 °C , the threshold value required for an object to be traveling at a supersonic speed is approximately 343 m/s, . Speeds greater than 5 times the speed of sound are often referred to as hypersonic...
flight of aircraft.
The shock wave is one of several different ways in which a gas in a
supersonicThe term supersonic is used to define a speed that is over the speed of sound . In dry air at 20 °C , the threshold value required for an object to be traveling at a supersonic speed is approximately 343 m/s, . Speeds greater than 5 times the speed of sound are often referred to as hypersonic...
flow can be compressed. Some other methods are isentropic compressions, including
PrandtlLudwig Prandtl was a German scientist. He was a pioneer in the development of rigorous systematic mathematical analyses which he used to underlay the science of aerodynamics, which have come to form the basis of the applied science of aeronautical engineering...
-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 the intake of a
scramjetA scramjet is a variation of a ramjet distinguished by supersonic combustion. A scramjet, like a ramjet, essentially consists of a constricted tube through which inlet air is compressed by the high speed of the vehicle, a combustion chamber where fuel is combusted, and a nozzle through which the...
. The appearance of pressure-drag on supersonic aircraft is mostly due to the effect of shock compression on the flow.
Due to nonlinear steepening
Shock waves can form due to steepening of ordinary waves. The best-known example of this phenomenon is ocean waves that form
breaker*Breaker , an engineering vehicle attachment*Breaker , a shallow over which waves break*Breaker , from the G.I. Joe comic universe*Breaker , by heavy metal band Accept*The Breaker, a book by Minette Walters...
s on the
shoreA shore or shoreline is the fringe of land at the edge of a large body of water, such as an ocean, sea, or lake. In Physical Oceanography a shore is the wider fringe that is geologically modified by the action of the body of water past and present, while the beach is at the edge of 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 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 the dependence of the sound speed on
temperatureIn physics, temperature is a physical property of a system that underlies the common notions of hot and cold; something that feels hotter generally has the higher temperature. Temperature is one of the principal parameters of thermodynamics...
and
pressurePressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
. 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. While shock formation by this process does not normally happen to sound waves in Earth's atmosphere, it is thought to be one mechanism by which the
solarThe Sun is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 99.86% of the Solar System's mass....
chromosphereThe chromosphere is a thin layer of the Sun's atmosphere just above the photosphere, roughly 2,000 kilometres deep....
and
coronaA corona is a type of plasma "atmosphere" of the Sun or other celestial body, extending millions of kilometres into space, most easily seen during a total solar eclipse, but also observable in a coronagraph...
are heated, via waves that propagate up from the solar interior.
Analogies
A shock wave may be described as the furthest point upstream of a moving object which "knows" about 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 coneA Light cone is the path that a flash of light would take through spacetime. As time progresses, the light from the flash spreads out in a circle, and the result is a cone...
described in the theory of
special relativitySpecial relativity is the physical theory of measurement in inertial frames of reference proposed in 1905 by Albert Einstein in the paper "On the Electrodynamics of Moving Bodies"...
.
To get a shock wave something has to be travelling faster than the local speed of sound. In that case some parts of the air around the aircraft are travelling at exactly the speed of sound with the aircraft, so that the sound waves leaving the aircraft pile up on each other, similar to a tailback on a road, and a shock wave forms, the pressure increases, and then spreads out sideways. Because of this amplification effect, a shock wave is very intense, more like an explosion when heard (not coincidentally, since explosions create shock waves).
Analogous phenomena are known outside fluid mechanics. For example, particles accelerated beyond the
speed of lightIn physics, the speed of light is a physical constant, the speed at which electromagnetic radiation, such as light, travels in free space . Its value is 299,792,458 metres per second...
in a
refractive mediumRefraction is the change in direction of a wave due to a change in its velocity. This is most commonly observed when a wave passes from one medium to another...
(where the speed of light is less than that in a
vacuumIn everyday usage, vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure. The word comes from the Latin term for "empty," but in reality, no volume of space can ever be perfectly empty...
, such as
waterWater is an ubiquitous chemical substance that is composed of hydrogen and oxygen and is essential for all known forms of life.In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71%...
) create visible shock effects, a phenomenon known as
Cherenkov radiationCherenkov radiation is electromagnetic radiation emitted when a charged particle passes through an insulator at a constant speed greater than the speed of light in that medium. The characteristic "blue glow" of nuclear reactors is due to Cherenkov radiation...
.
Examples
Below are a number of examples of shock waves, broadly grouped with similar shock phenomena:
Moving shock
- usually consists of a shockwave propagating into a stationary medium
- In this case, the gas ahead of the shock is stationary (in the laboratory frame), and the gas behind the shock is supersonic in the laboratory frame. The shock propagates with a wave front which is normal (at right angles) to the direction of flow. The speed of the shock is a function of the original pressure ratio between the two bodies of gas.
- Moving shock
In fluid dynamics, a moving shock is a shock wave that is traveling through a fluid medium with a velocity relative to the velocity of the fluid already making up the medium. As such, the normal shock relations require modification to calculate the properties before and after the moving shock...
s are usually generated by the interaction of two bodies of gas at different pressure, with a shock wave propagating into the lower pressure gas, and an expansion wave propagating into the higher pressure gas.
- Examples: Balloon bursting, Shock tube
A shock tube is a device used primarily to study gas phase combustion reactions. Shock tubes can also be used to study aerodynamic flow under a wide range of temperatures and pressures that are difficult to obtain in other types of testing facilities.- Working :A simple shock tube is a metal tube...
, shock wave from explosionA blast wave in fluid dynamics is the pressure and flow resulting from the deposition of a large amount of energy in a small very localised volume...
Detonation wave
- A detonation
Detonation is a process of combustion in which a supersonic shock wave is propagated through a fluid due to an energy release in a reaction zone. It is the more powerful of the two general classes of combustion, the other one being deflagration. In a detonation, the shock compresses the material...
wave is essentially a shock supported by a trailing exothermic reaction. It involves a wave traveling through a highly combustible or chemically unstable medium, such as an oxygen-methane mixture or a high explosive. The chemical reaction of the medium occurs following the shock wave, and the chemical energy of the reaction drives the wave forward.
- A detonation wave follows slightly different rules from an ordinary shock since it is driven by the chemical reaction occurring behind the shock wave front. In the simplest theory for detonations, an unsupported, self-propagating detonation wave proceeds at the Chapman-Jouguet
The Chapman-Jouguet condition holds approximately in detonation waves. It states that the detonation proceeds at a velocity at which the reacting gases just reach sonic velocity as the reaction ceases....
velocity. A detonation will also cause a shock of type 1, above to propagate into the surrounding air due to the overpressure induced by the explosion.
- When a shockwave is created by high explosives such as TNT
Trinitrotoluene , or more specifically, 2,4,6-trinitrotoluene, is a chemical compound with the formula C
6H
23CH
3. This yellow-coloured solid is a reagent in chemistry but is best known as a useful explosive material with convenient handling properties...
(which has a detonation velocity of 6,900 m/s), it will always travel at high, supersonicThe term supersonic is used to define a speed that is over the speed of sound . In dry air at 20 °C , the threshold value required for an object to be traveling at a supersonic speed is approximately 343 m/s, . Speeds greater than 5 times the speed of sound are often referred to as hypersonic...
velocityIn physics, velocity is the rate of change of position. It is a vector physical quantity; both speed and direction are required to define it. In the SI system, it is measured in meters per second: or ms-1. The scalar absolute value of velocity is speed...
from its point of origin.
Detached shock
- These shocks are curved, and form a small distance in front of the body. Directly in front of the body, they stand at 90 degrees to the oncoming flow, and then curve around the body. Detached shocks allow the same type of analytic calculations as for the attached shock, for the flow near the shock. They are a topic of continuing interest, because the rules governing the shock's distance ahead of the blunt body are complicated, and are a function of the body's shape. Additionally, the shock standoff distance varies drastically with the temperature for a non-ideal gas, causing large differences in the heat transfer to the thermal protection system of the vehicle. See the extended discussion on this topic at Atmospheric reentry
Atmospheric reentry refers to the movement of human-made or natural objects as they enter the atmosphere of a planet from outer space, in the case of Earth from an altitude above the "edge of space." This article primarily addresses the process of controlled reentry of vehicles which are intended...
. These follow the "strong-shock" solutions of the analytic equations, meaning that for some oblique shocks very close to the deflection angle limit, the downstream Mach number is subsonic. See also bow shockA bow shock, also called a detached shock, is a curved, stationary shock wave that is found in supersonic flow past a finite body. Unlike an oblique shock, the bow shock is not necessarily attached to the tip of the body. Oblique shock angles are limited in formation based on the corner angle and...
or oblique shockAn oblique shock wave, unlike a normal shock, is inclined with respect to the incident upstream flow direction. It will occur when a supersonic flow encounters a corner that effectively turns the flow into itself and compresses. The upstream streamlines are uniformly deflected after the shock wave...
- Such a shock occurs when the maximum deflection angle is exceeded. A detached shock is commonly seen on blunt bodies, but may also be seen on sharp bodies at low Mach numbers.
- Examples: Space return vehicles (Apollo, Space shuttle), bullets, the boundary (Bow shock
A bow shock is a boundary between a magnetosphere and an ambient medium. For stars, this is typically the boundary between their stellar wind and the interstellar medium....
) of a magnetosphereA magnetosphere is a highly magnetized region around and possessed by an astronomical object. Earth is surrounded by a magnetosphere, as are the magnetized planets Mercury, Jupiter, Saturn, Uranus, and Neptune. Jupiter's moon Ganymede is magnetized, but too weak to trap solar wind plasma. Mars has...
. The name "bow shock" comes from the example of a bow waveA bow wave is the wave that forms at the bow of a ship when it moves through the water. As the bow wave spreads out, it defines the outer limits of a ship's wake. A large bow wave slows the ship down, poses a risk to smaller boats, and in a harbor can cause damage to shore facilities and moored ships...
, the detached shock formed at the bow (front) of a ship or boat moving through water, whose slow surface wave speed is easily exceeded (see ocean surface waveIn fluid dynamics, wind waves or, more precisely, wind-generated waves are surface waves that occur on the free surface of oceans, seas, lakes, rivers, and canals or even on small puddles and ponds. They usually result from the wind blowing over a vast enough stretch of fluid surface. Some waves...
).
Attached shock
- These shocks appear as "attached" to the tip of a sharp body moving at supersonic speeds.
- Examples: Supersonic wedges and cones with small apex angles
- The attached shock wave is a classic structure in aerodynamics because, for a perfect gas and inviscid flow field, an analytic solution is available, such that the pressure ratio, temperature ratio, angle of the wedge and the downstream Mach number can all be calculated knowing the upstream Mach number and the shock angle. Smaller shock angles are associated with higher upstream Mach numbers, and the special case where the shock wave is at 90 degrees to the oncoming flow (Normal shock), is associated with a Mach number of one. These follow the "weak-shock" solutions of the analytic equations.
Recompression shock
- These shocks appear when the flow over a transonic body is decelerated to subsonic speeds.
- Examples: Transonic wings, turbines
- Where the flow over the suction side of a transonic wing is accelerated to a supersonic speed, the resulting re-compression can be by either Prandtl-Meyer compression or by the formation of a normal shock. This shock is of particular interest to makers of transonic devices because it can cause separation of the boundary layer at the point where it touches the transonic profile. This can then lead to full separation and stall on the profile, higher drag, or shock-buffet, a condition where the separation and the shock interact in a resonance condition, causing resonating loads on the underlying structure.
Shock in a pipe flow
- This shock appears when supersonic flow in a pipe is decelerated.
- Examples: Supersonic ramjet
A ramjet, sometimes referred to as a stovepipe jet, or an athodyd, is a form of jet engine using the engine's forward motion to compress incoming air, without a rotary compressor...
, scramjetA scramjet is a variation of a ramjet distinguished by supersonic combustion. A scramjet, like a ramjet, essentially consists of a constricted tube through which inlet air is compressed by the high speed of the vehicle, a combustion chamber where fuel is combusted, and a nozzle through which the...
, needle valve
- In this case the gas ahead of the shock is supersonic (in the laboratory frame), and the gas behind the shock system is either supersonic (oblique shocks) or subsonic (a normal shock) (Although for some oblique shocks very close to the deflection angle limit, the downstream Mach number is subsonic.) The shock is the result of the deceleration of the gas by a converging duct, or by the growth of the boundary layer on the wall of a parallel duct.
Shock waves in rapid granular flows
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 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. Such study is important in estimating impact pressures exerted by avalanches and granular flows on defense structures or infrastructure along the channel and in the run-out zones, and to study the complex flow dynamics around the obstacles and in depositions when the mass comes suddenly to a standstill.
Shock waves in astrophysics
Astrophysical environments feature many different types of shock waves. Some common examples are Supernovae shock waves or blast waves traveling through the interstellar medium, the
bow shockA bow shock is a boundary between a magnetosphere and an ambient medium. For stars, this is typically the boundary between their stellar wind and the interstellar medium....
caused by the earth's magnetic field colliding with the
solar windThe solar wind is a stream of charged particles ejected from the upper atmosphere of the sun. It consists mostly of electrons and protons with energies of about 1 keV. The stream of particles varies in temperature and speed with the passage of time...
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.
See also
- Atmospheric focusing
Atmospheric focusing is a phenomenon occurring when a large shockwave is produced in the atmosphere, as in a nuclear explosion or large extraterrestrial object impact. The shockwave is refracted horizontally by density variations in the atmosphere so that it can have impacts in localized areas much...
- Atmospheric reentry
Atmospheric reentry refers to the movement of human-made or natural objects as they enter the atmosphere of a planet from outer space, in the case of Earth from an altitude above the "edge of space." This article primarily addresses the process of controlled reentry of vehicles which are intended...
- Čerenkov radiation
- Explosions
- Hydraulic jump
A hydraulic jump is a phenomenon in the science of hydraulics which is frequently observed in open channel flow such as rivers and spillways. When liquid at high velocity discharges into a zone of lower velocity, a rather abrupt rise occurs in the liquid surface...
- Mach wave
In fluid dynamics, a Mach wave is a pressure wave traveling with the speed of sound caused by a slight change of pressure added to a compressible flow. These weak waves can combine in supersonic flow to become a shock wave if sufficient Mach waves are present at any location. Such a shock wave is...
- Magnetopause
The magnetopause is the abrupt boundary between a magnetic field, and surrounding plasma. The magnetopause ripples, flaps, and moves inward and outward in response to varying solar wind conditions....
- Normal shock tables
The Normal shock tables are a series of tabulated data listing the various properties before and after the occurrence of a normal shock wave. With a given upstream Mach number, the post-shock Mach number can be calculated along with the pressure, density, temperature, and stagnation pressure ratios...
- Shocks and Discontinuities (MHD)
- Shock (mechanics)
A mechanical or physical shock is a sudden acceleration or deceleration caused, for example, by impact, drop, kick, earthquake, or explosion. Shock is a transient physical excitation....
- Sonic boom
The term sonic boom is commonly used to refer to the shocks caused by the supersonic flight of an aircraft. Sonic booms generate enormous amounts of sound energy, sounding much like an explosion...
- Undercompressive shock wave
An undercompressive shock wave is a shock wave that does not fulfill the Peter Lax conditions.-Details:Ordinary shock waves are compressive, that is, they fulfill the Peter Lax conditions: the characteristic speed behind the shock is greater than the speed of the shock, which is greater than the...
- Shock diamond
Shock diamonds is a formation of stationary wave patterns that appears in the exhaust plume of an aerospace propulsion system, such as a supersonic jet engine, rocket, ramjet, or scramjet when it is operated in an atmosphere.Shock diamonds are formed when the supersonic exhaust from a nozzle is...
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