Investigations of Transonic Ludwieg Tubes : Part3 Effects of Plenum Exhaust System on Starting Process of Tunnel Test Section

Abstract

The starting time of a transonic Ludwieg tube is dependent on the timing of opening the main tunnel valve and the plenum exhaust valve, as well as the plenum chamber volume, the exhaust rate, the opening times of the main and the exhaust valves, and so on. In the previous paper, the starting process of the transonic Ludwieg tube with a main valve downstream of the transonic test section was studied in the case that the main and the exhaust valves started to open simultaneously. In the present paper, starting to open the plenum exhaust valve was delayed or advanced from the opening of the main valve, and the effect of plenum exhaust delays on the staring time of the transonic test section was discussed. Further, the effect of the orifice position in the plenum exhaust system on the starting time was experimentally investigated. The starting time becomes a little smaller by locating the orifice at the downstream section of the exhaust valve.