### High-enthalpy shock/boundary-layer interaction on a double wedge

Jean-Paul Davis, Caltech
Interaction between a shock wave and a boundary layer at a compression
corner can produce a region of separated flow, the size of which is
important in determining aerodynamic forces. Real gas effects (e.g.,
in a high enthalpy dissociating flow) on the length of the separated
region are not well known. Experiments to measure separation length
are performed in the T5 Hypervelocity Shock Tunnel on a double wedge
configuration with nitrogen test gas. The double wedge geometry allows
greater control over local flow conditions at separation and, at high
incidence angle, can produce stronger real gas effects due to dissociation
behind the leading shock. Local flow conditions at separation
are found by computational reconstruction of the external nonequilibrium
flow field. Analysis of separation length
for a laminar non-reacting boundary layer leads to a new scaling based on
triple-deck theory, extending a previous result to arbitrary viscosity
law and non-adiabatic walls. A classification is introduced which
divides mechanisms for real gas effects into mechanisms acting internal
and external to the boundary layer. External mechanisms are shown to
decrease separation length in high enthalpy dissociating flows. Internal
mechanisms are considered qualitatively. A limited numerical study
shows that internal mechanisms for real gas effects are
relatively unimportant in the present experiments. Correlations are
presented of experimentally measured separation length against
reattachment pressure ratio and Reynolds Number using the new scaling law
(which includes external mechanisms for real gas effects). Real
gas effects on reattachment heat flux will also be discussed.

For more details, see my ISSW
21 paper.

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Last Modified: March 20, 1998