Shock-tube studies with incident liquefaction shocks
Incident liquefaction shock waves, with a superheated-vapor upstream state, are studied in shock-tube experiments. Such a shock can occur in any gas, such as n-octane, with a sufficient number of vibrational degrees of freedom: the test fluids in these experiments are fluorocarbons. The shock tube is heated to a test temperature in the range 40-170 C, and a lightweight driver piston is used to avoid Rayleigh-Taylor instabilities at the contact surface. Photographs show the emerging liquefaction-shock structure in an observation chamber at the end of the shock-tube test section. The incident shock splits into a gas-phase forerunner shock and a following condensation shock. At the triple point, where the splitting occurs, the state downstream of the forerunner shock is critically supersaturated, i.e., far from equilibrium. The three-dimensional liquefaction-shock structure shows an approximately self-similar form, which permits experimental determination of the mixture soundspeed. At sufficiently high shock velocities, transition from a smooth liquefaction shockfront to a turbulent front is observed.
Shock Tubes and Waves
- Pub Date:
- Shock Tubes;
- Shock Wave Propagation;
- Shock Fronts;
- Fluid Mechanics and Heat Transfer