Detached shock
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Detached shock is referred to situation in which shock isn't touching the body. This occurs when a supersonic flow is inclined to surface area (boundary conditions). If the inclined angle is exceeded maximum value the Bar-Meir solution to oblique shock results into a square root of negative number. The physical implication is that there isn't a shock angle that can exist that satisfies normal shock and the boundary conditions in the same time. Thus, a normal shock occurs. The normal shock occur same distance from the body which depends on the Mach number (flow velocity and speed of sound).
[edit] History
The detached shock has a significance in increasing the drag in super sonic flow. This phenomenon was discovered when researchers tried to increase the velocity of airplanes and the propeller show remarkable reduction in power above certain point which turn to shock and detached shock. This phenomenon is significant in reentry of space vehicle when the major contribution to the heating is due to normal shock (detached shock) temperature increase. The mathematical solution of this problem was found in 2004 that explain what physically was known since Mach discovery.
[edit] External links
- Fundamentals of compressible flow mechanics - Genick Bar-Meir, Ph.D.
- Shockwave calculator (Java applet).