A $55 Shock Tube for Simulated Blast Waves

TL;DR

This paper presents a low-cost, easily assembled shock tube using a modified air pistol and standard pipe to generate controlled blast waves for testing sensors and materials, with pressures tunable by the number of pumps used.

Contribution

It introduces a simple, inexpensive shock tube design that can produce repeatable blast pressures suitable for sensor calibration and testing, using common household items.

Findings

Peak pressures ranged from 30.13 kPa to 101.99 kPa depending on pumps used.

Cycle time between shots was 30 to 45 seconds.

Design is cost-effective and easily accessible for field testing.

Abstract

Shock tubes are commonly employed to test candidate armor materials, validate numerical models, and conduct simulated blast experiments in animal models. As DoD interests desire to field wearable sensors as blast dosimeters, shock tubes may also serve for calibration and testing of these devices. The high blast pressures needed for experimental testing of candidate armors are unnecessary to test these sensors. An inexpensive, efficient, and easily available way of testing these pressure sensors is desirable. It is known that releasing compressed gas suddenly can create a repeatable shock front, and the pressures can be finely tuned by changing the pressure to which the gas is compressed. A Crosman 0.177 caliber air pistol was used (without loading any pellets) to compress and release air in one end of a 24 inch long 3/4 inch diameter standard pipe nipple to simulate a blast wave at the other end of the tube. A variable number of pumps were used to vary the peak blast pressure. As expected, the trials where 10 pumps were used to compress the air resulted in the largest average peak pressure of 101.99 kPa (+/- 2.63 kPa). The design with 7 pumps had the second biggest peak pressure, with an average peak pressure of 89.11 kPa (+/-1.77 kPa). The design with 5 pumps had the third largest peak pressure, with an average peak pressure of 78.80 kPa (+/-1.74 kPa). 3 pumps produced an average peak pressure of 61.37 kPa (+/-2.20 kPa). 2 pumps produced an average peak pressure of 48.11 kPa (+/-1.57 kPa). The design with just 1 pump had the smallest peak pressure and produced an average peak pressure of 30.13 kPa (+/-0.79 kPa). This inexpensive shock tube design had a shot-to-shot cycle time of between 30 and 45 seconds.