Experiments of transitional shock wave boundary layer interactions over a 6°and a 10°6 compression ramp were performed at a Mach number of 1.65. The unit Reynolds number was varied by a factor of two between 5.6 million per metre and 11 million per metre. Schlieren flow visualization was performed, and mean flow measurement were made using Pitot probes.

Free-interaction theory was verified from pressure measurements for all operating conditions.

A new non-dimensional parameter was developed for scaling the strength of the imposed shock, that incorporated free-interaction theory, and accounted for Reynolds number effects.

The validity of this new scaling was supported by the reconciliation of the large scatter in a diverse collection of experimental results on the length scales of transitional interactions.

Finally, a universal scaling for the length scales of shock induced separation with laminar or turbulent upstream conditions is proposed.