Area 3

At Area 3 is a 2.4-m-diameter (8-ft), 78-m-long (257-ft) shock tube, used for airblast testing of structures up to 1-m wide at pressures up to 760 kPa (110 psi). It is among the largest privately owned and operated shock tubes in the United States available for contract research. The 27-m-long explosive driver section is made of 2.4-m-long AS16-70 steel tubes with wall thickness up to 44 mm, accommodating a maximum pressure of 17 MPa (2500 psi). A 9-m-long floor ramp section provides a smooth transition from the driver to the 21-m flat floor section, which in turn permits the formation of a uniform shock wave in the tube before the wave reaches the 3-m test section.

The test section is shock isolated from the rest of the tube to prevent disturbances from the explosion from reaching the target and associated instrumentation. This section also has a door to permit easy access and several ports with glass windows for photography. Explosive charges are distributed along the driver section of the tube. The relative amplitudes of static overpressure and dynamic pressure are controlled by introducing gases lighter or heavier than air into different compartments in the tube, separated by thin plastic membranes. Several tests performed on scale-model structures have involved up to 60 channels of active instrumentation for pressure, acceleration, strain, displacement, and high-speed photography.

A smaller shock tube at Area 3, measuring 0.6-m in diameter (2-ft) and 15-m long (50-ft) is used primarily to develop simulation techniques for producing unique airblast environments, including techniques for use in the larger shock tube.

Also at Area 3 is a gas-propelled rail-sled facility for launching aircraft or other models weighing up to 100 kg at velocities up to 175 m/s or 50 kg to 250 m/s. This facility uses a 300-mm-diameter piston in a 12-m-long tube and a high-strength cable and pulley system to gradually accelerate the sled. After the projectile is released from the sled, the sled is diverted from the projectile and target, and the piston enters a soft-recovery chamber. Rearrangement of the launch tube and piston allows the facility to be used directly as a 300-mm-diameter gas gun.

Another facility at Area 3 is the natural-gas pipeline test facility used for evaluating the effects of deflagration and detonation of gas from accidental releases. Storage tanks for 15 cubic meters of gas at 7 MPa (1000 psi) are connected to various arrangements of pipes and valves for tests under precisely controlled conditions of gas composition, pressure, and flow rate.