supersonic shockwaves

by Hugh

I’m not a gadget/gear junkie, but the mechanical engineer in me (I didn’t like much of my engineering courses, but I enjoyed fluid dynamics) thought this photo was pretty darned neat:

A closeup [below], notice the visual distortion caused by the shockwaves… cool huh? The jet is not yet supersonic, but is in the transonic region. The air around the plane is accelerated to supersonic speed when it encounters an obstruction (like a bump on the fuselage). Shocks within the supersonic flow (often causing it to decelerate to subsonic conditions) produce large gradients in air density and index of refraction, bending the light differentially on either side of the shock. Those pressure waves can be seen radiating from specific points on the aircraft (including the canopy). The above was compiled from various people who emailed me!

shockwaves image

[photo by BZ]