Fast diaphragmless shock tube driver design for Richtmyer-Meshkov instability experiments

The Los Alamos National Laboratory Vertical Shock Tube (VST) facility studies the Richtmyer-Meshkov instability, providing data for improvement of theoretical understanding, model development, and validation of simulations. Traditional shock tubes use a diaphragm to separate a high-pressure region from a low pressure driven region; puncturing the diaphragm results in the generation of a shock. Our team developed a diaphragmless piston-operated driver to allow for high shot repetition rates, increasing the shot rate from ~1 per hour to ~5-10 per hour. This approach also has the benefit of providing a cleaner flow to the system, compared to conventional shock tubes where contaminants are introduced from the diaphragm itself. Our previous design suffered from a change in volume during piston motion that occurred on the order of milliseconds, creating suction in the driven section that impacted the initial conditions of the system downstream. To reduce the effects of the driver motion on the system, a new piston design was engineered to eliminate volume change before breach, and provide more control of speed and movement through improved chamber isolation.