Investigation of transonic Ludwieg tubes. I - Starting process in the case of an upstream valve

The starting process of a transonic Ludwieg tube with a quick-opening valve upstream of the transonic test section was studied over a range of plenum chamber volumes and flow rates using a plenum exhaust system. Results show that a steady and uniform flow in the test section is established when the mass flow rate through the porous wall of the test section becomes equal to that through the plenum exhaust system. Wave diagrams showing the starting process are given, and the flow mechanism of the starting process is examined.