Shock Tube Design for High Intensity Blast Waves for Laboratory Testing of Armor and Combat Materiel

TL;DR

This paper explores three methods to enhance shock tube peak pressures from about 1 MPa to over 5 MPa, enabling more realistic laboratory testing of armor and combat materiel against blast waves.

Contribution

It introduces and evaluates three techniques—Shchelkin spiral, bottleneck design, and solid fuel addition—to significantly increase shock tube pressure capabilities.

Findings

Shchelkin spiral increased peak pressure to 5.33 MPa.

Bottleneck design raised peak pressure to over 2.6 MPa.

Adding solid fuel increased peak pressure to 1.70 MPa.

Abstract

Shock tubes create simulated blast waves which can be directed and measured to study blast wave effects under laboratory conditions. It is desirable to increase available peak pressure from ~1 MPa to ~5 MPa to simulate closer blast sources and facilitate development and testing of personal and vehicle armors. Three methods were investigated to increase peak simulated blast pressure produced by an oxy-acetylene driven shock tube while maintaining suitability for laboratory studies. The first method is the addition of a Shchelkin spiral priming section which works by increasing the turbulent flow of the deflagration wave, thus increasing its speed and pressure. This approach increased the average peak pressure from 1.17 MPa to 5.33 MPa while maintaining a relevant pressure-time curve (Friedlander waveform). The second method is a bottleneck between the driving and driven sections. Coupling a 79 mm diameter driving section to a 53 mm driven section increased the peak pressure from 1.17 MPa to 2.25 MPa. Using a 103 mm driving section increased peak pressure to 2.64 MPa. The third method, adding solid fuel to the driving section with the oxy-acetylene, resulted in a peak pressure increase to 1.70 MPa.