The Characterization and Feasibility of a Low-Duty-Cycle Diaphragmless Shock Tube

The feasibility and characterization of a novel diaphragmless shock tube was examined at the National Aerothermochemistry Laboratory at Texas A&M University. The goal was to design a facility that reliably produces shock waves through air in a repeatable manner sufficient for statistical analysis. The device is modular, automated, and compact. The proposed diaphragmless shock tube uses a shock wave generating mechanism that consists of a rotating door and locking cam-shaft system. The facility produced the desired driver gas pressures repeatedly to within 0.31% at low-duty-cycle of 6 seconds. The driven gas pressure profiles within the test-section suggest that shock waves may be forming within test section for a driver gas pressure of 200 psig and above, which corresponds to shock wave Mach numbers of 1.7 to 2.0. The measured wave speeds were within 3.1% of that predicted by ideal shock tube theory; however, the induced driven gas pressures within the constant pressure region were approximately half that expedited from ideal shock tube theory.