Fig 261; Ogive cylinder in free flight at M=1.7
This shadowgraph shows in remarkable detail the supersonic flow past a body of 2 centimeter radius at small incidence: an initial straight bow wave from a conical tip, weak shock waves generated by roughness on nose, a growing turbulent boundary layer over the cylindrical midsection, expansion fans at the start of the 2-degree conical boat tail and at the base, and transient shock waves from an unsteady turbulent wake.
Photograph from Aerodynamics Range facility, US
army Ballistic Research Laboratory
Fig 266; Sphere at M=1.53
A shadowgraph catches a 1.25-cm sphere in free flight through air. The flow is subsonic behind the part of the bow wave that is ahead of the sphere, and over its surface back to 45o. At about 90 o the laminar boundary layer separates through an oblique shock wave, and quickly becomes turbulent. The fluctuating wake generates a system of weak disturbances that merge into the second shock wave. This is a remarkable picture as it shows a detached normal shock, laminar boundary layer separation, an oblique shock, a turbulent wake, and a system of disturbances merging into an oblique shock.
Photograph by A .C. Charters.
Fig 271 Sphere flying over a perforated plate.
A shadowgraph shows a 9/16 inch sphere shot past
a plate with a line of 1/16 inch holes spaced 1/4 inch apart. The pressure
of the bow wave produces below the plate the classical diagram of the
Mach cone as the envelope of a series of expanding spherical acoustic
waves. This was used to measure the Mach number, which is seen to be 3.
A tiny vortex ring moving downward is formed at each hole, followed at
the right by a secondary ring moving upward.
This picture also shows (1) the reflection of an oblique shock from a
plate, and (2) the interaction of two oblique shock waves.
Photograph from U.S. Army Ballistic Research Laboratory