whateverWave source, whenMovement speedExceeds itswaveThis wave form can be called shock wave orshock wave。It is characterized by the jump change of wave front, that is, afrontal surface。The physical properties of the medium at the front have a sudden change, causing strong destruction.Shock waves usually propagate through the medium of matter.
Shock wave refers toDisturbancestayNonlinearPropagation in media.If itsmach numberandReynolds numberLarge enough,DispersionSmall enough,mediumDisturbances in may form discontinuities, which are related tophysical quantityJump occurs, and the motion of discontinuity forms shock wave.There are many disturbances that can form shock waves, such asBlast wave, ballistic wave, thunder, aircraft roar, etc.OnesineAn example of mathematical description is that Riemann Earnshaw wave formed by the disturbance of type F finally forms shock wave (seeNonlinear acoustics）。When Mach number is greater than 1, the disturbance is limited toconeIts surface can be used as a discontinuity.If media existsdissipation(e.gviscosity 、heat conductionEtc.),interruptedNot in anoodlesOn, but in athin layerThe latter is called interfault.[1]
Production principle
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shock waveIs a discontinuitypeakWhen propagating in the medium, this peak leads to the jump change of physical properties such as pressure, temperature and density of the medium.In nature, all explosions are accompanied by shock waves, and the shock waves always become larger than the local expansion speed of the materialsound velocityOccurs when.When in SoneThe wave source of the point is at the speed V exceeding the wave speedsWhen moving forward,Wave sourceThe motion of (an object) itself will excite the mediumDisturbance, thus arousing anotherwave。At this time, the moving object acts as the wave source of another wave, which is a series of waves centered on the moving track of the telecontrol objectspherical wave。
Since the velocity u of spherical wave is higher than the velocity V of objectsSmall, so it will form a V-shaped wave with the wave source as the vertex, which is called shock wave.
Usuallynuclear explosionExplosion centerpressureSharp rise makes the surrounding air violentshockFormed bywave。Shock waveSupersonic speedIt is one of the important killing and destructive factors of nuclear explosionBlast wave。It can also refer to the intensity caused by supersonic motioncompressAir flow.It is compared to the impact of a powerful force that affects something.
Common phenomenon
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Supersonic fighter
The speed of an aircraft exceeds 330 m/s“Sound barrier”Is broken, accompanied by aatmosphereThe shock wave propagates and produces a sound "explosion".
The shock wave isnuclear weaponThe main factors of killing and destroying.
The killing effect of shock wave on people can be divided into two types:
One is direct killing, that is, the damage caused by the direct action of the shock wave on the human body.
The second is indirect killing, which refers to the object orEjectionInjuries to people caused by objects, such as building collapse and human injury.Therefore, when encountering a nuclear attack, you should lie down in the nearest low-lying place, and do not hide in or behind buildings to avoid indirect injury.
