Shock wave

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A shock wave is a term used in fluid mechanics . It describes an unsteady (abrupt) change in the flow condition that only occurs with supersonic flow in compressible media:

• The density , pressure and temperature of the medium increase
• the flow velocity and thus the Mach number decrease.

Depending on the position of the shock front relative to the direction of flow, one differentiates:

• a vertical shock wave always brings supersonic flow to subsonic while maintaining the direction of flow
• an oblique shock wave reduces the speed (but not necessarily to subsonic speed) and changes the direction of flow.

Compression shocks occur when the supersonic flow has to avoid an obstacle or the counter pressure increases too much, e.g. B. inlet on a subsonic engine . Since pressure disturbances propagate at the local speed of sound , the information about them cannot be carried upstream in a supersonic flow. An adaptation of the flow condition takes place abruptly with one shock.

See also

• Shock wave
• compression
• Supersonic flight
• Jump - similar behavior of liquids in open channels

literature

• JD Anderson: Modern Compressible Flow. McGraw-Hill, Boston 2003, ISBN 0-07-112161-7 .
• K. Oswatitsch: Gas dynamics. Springer, Vienna 1952, DNB 453668356 .