Free-Piston Shock Tunnel Test Technique Development: An AEDC/DLR Cooperative Program

Computational Simulation of Scramjet Combustors - A Comparison between Quasi-One Dimensional and 2-D Numerical Simulations

“…In a free-piston shock tunnel (as shown in Figure 27), the driver is a piston that slides freely within the compression tube [30]. The piston is driven through the force of a highly compressed driving gas in the gas reservoir.…”

“…The piston is driven through the force of a highly compressed driving gas in the gas reservoir. The compression tube is generally filled with light gas typically helium at a low pressure with respect to the gas in the reservoir [30]. A heavy metal diaphragm (P) separates the compression tube and shock tube.…”

“…A heavy metal diaphragm (P) separates the compression tube and shock tube. The shock tube is usually filled with air as a test gas and is separated from the facility nozzle by a second diaphragm (s) made out of a very thin and light material [30]. To start the tunnel, a force is applied on the piston by the high pressure gas in the gas reservoir which causes it to traverse through the compression tube, pressurizing the light gas inside it.…”

“…To start the tunnel, a force is applied on the piston by the high pressure gas in the gas reservoir which causes it to traverse through the compression tube, pressurizing the light gas inside it. When the pressure within the compression tube reaches a certain level, it will result in the rupture of diaphragm (P) which will initiate a normal shock wave to propagate through the shock tube [30]. The shock wave compresses the test gas within the shock tube as it propagates until the point where it hits the secondary diaphragm (S), ruptures it, reflects back and propagates in the opposite direction.…”

“…This compresses the test gas second time, causing a further increase in the temperature and pressure [30]. In AEDC FPST facility, test gas can achieve a high pressure up to 2000 atm and high temperature of 10,000 K [30].…”