A review of diaphragmless shock tubes for interdisciplinary applications

Shock tubes have emerged as an effective tool for applications in various fields of research and technology. The conventional mode of shock tube operation employs a frangible diaphragm to generate shock waves. The last half-century has witnessed significant efforts to replace this diaphragm-bursting method with fast-acting valves. These diaphragmless methods have good repeatability, quick turnaround time between experiments, and produce a clean flow, free of diaphragm fragments, in contrast to the conventional diaphragm-type operation. The constantly evolving valve designs target shorter opening times for improved performance and efficiency. The present review is a compilation of the different diaphragmless shock tubes that have been conceptualized, developed, and implemented for various research endeavors. The discussions focus on essential factors, including the actuation mechanism, driver-driven configurations, valve opening time, shock formation distance, and operating pressure range, that ultimately influence the shock wave parameters obtained in the shock tube. A generalized mathematical model to study the behavior of these valves is developed. The advantages, limitations, and challenges in improving the performance of the valves are described. Finally, the present-day applications of diaphragmless shock tubes have been discussed, and their potential scope in expanding the frontiers of shock wave research and technology is presented.