A Ludwieg tube is a cheap and efficient way of producing supersonic flow. Mach numbers up to 4 are easily obtained without any additional heating of the flow. With heating, Mach numbers of up to 11 can be reached.
Famous quotes containing the word tube:
“One of the great natural phenomena is the way in which a tube of toothpaste suddenly empties itself when it hears that you are planning a trip, so that when you come to pack it is just a twisted shell of its former self, with not even a cubic millimeter left to be squeezed out.”
—Robert Benchley (1889–1945)