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The Mach angle is acute, showing that the body exceeds Mach 1. The angle of the Mach wave (~59 degrees) indicates a velocity of about Mach 1.17. In fluid dynamics, a Mach wave, also known as a weak discontinuity, [1] [2] is a pressure wave traveling with the speed of sound caused by a slight change of pressure added to a compressible flow.
A blast wave reflecting from a surface and forming a mach stem. The air burst is usually 100 to 1,000 m (330 to 3,280 ft) above the hypocenter to allow the shockwave of the fission or fusion driven explosion to bounce off the ground and back into itself, combining two wave fronts and creating a shockwave that is more forceful than the one resulting from a detonation at ground level.
English: Chronological sequence of the Mach-reflected detonation wave of a 20 kiloton air burst (burst height 540 metres equivalent to a maximized 15 psi or 103 kPa range) at 0.5, 1.25 and 3 seconds after detonation. The blue curve indicates the propagating shock front (refraction due to fireball is neglected here).
The picture shows a 20 kiloton air burst at 540 meters, to optimize the area covered by at least 15 psi blast damage. Mach stem formation occurs when a blast wave reflects off the ground and the reflection catches up with the original shock front, therefore creating a high pressure zone that extends from the ground up to a certain point called ...
This is caused by the nonlinear behavior of shock waves. When the blast wave from an air burst reaches the ground it is reflected. Below a certain reflection angle, the reflected wave and the direct wave merge and form a reinforced horizontal wave, known as the '"Mach stem" and is a form of constructive interference.
Shock diamonds are the bright areas seen in the exhaust of this statically mounted Pratt & Whitney J58 engine on full afterburner.. Shock diamonds (also known as Mach diamonds or thrust diamonds, and less commonly Mach disks) are a formation of standing wave patterns that appear in the supersonic exhaust plume of an aerospace propulsion system, such as a supersonic jet engine, rocket, ramjet ...
As a result of the data gathered on the size of the blast, the detonation height for the bombing of Hiroshima was set at 1,885 feet (575 m) to take advantage of the Mach stem blast reinforcing effect. [137] The final Nagasaki burst height was 1,650 feet (500 m) so the Mach stem started sooner. [138]
Mach reflection can exist in steady, pseudo-steady and unsteady flows. When a shock wave, which is moving with a constant velocity, propagates over a solid wedge, the flow generated by the shock impinges on the wedge thus generating a second reflected shock, which ensures that the velocity of the flow is parallel to the wedge surface.