Ludwieg tube

A Ludwieg tube is a wind tunnel that produces supersonic flow for short periods of time.

A large evacuated dump tank is separated from the downstream end of a convergent-divergent nozzle by a diaphragm or fast acting valve.

To start the tunnel, the diaphragm is ruptured, e.g., by piercing it with a suitable cutting device, or opening the valve respectively.

However, by taking advantage of multiple quasi-static flows between expansion wave reflections, experimentation times of up to 6 seconds can be achieved.

Professor Ludwieg was also responsible for the experimental demonstration and explanation of the large effect of sweep on the drag of transonic wings (his dissertation in 1937).