In the reflection of shock waves off a surface von
Neumann’s theory assumes compressible and inviscid flow. It
also assumes the reflecting surface to be perfectly smooth, nonporous,
and adiabatic. It is found to be accurate for a wide
range of regular reflection patterns and limited to very strong
shocks in the case of Mach reflection. However experiments
have shown that regular reflection persists beyond the
theoretical limit. It has been postulated that this is due to the
development of a viscous boundary layer behind the reflection
point, an explanation now well accepted. However, the
assumption of an adiabatic wall has persisted over many years.
An experiment has been devised where two inclined surfaces
on either side of a symmetry plane and impacted by a
propagating shock wave normal to the plane would show any
differences in reflection behaviour, if they were equally smooth
but of different conductivities. Tests were conducted at incident
shock Mach numbers from 1.30 to 1.59, and shock incidence
angles of 20 to 55 degrees with a copper surface on one side
and a glass surface on the other. Detectable differences in
reflection geometry were established in most cases, indicating a
possible small influence on reflection patterns.
Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016.