Temporally and Spatially Resolved Reflected Overpressure Measurements in the Extreme Near Field

Area of Science:

• Explosion mechanics and structural engineering.
• Experimental fluid dynamics and shock wave physics.

Background:

• Accurate prediction of blast wave loadings is crucial for designing blast-resistant structures and protective systems.
• Existing empirical methods are reliable in the far field, but near-field pressure data is lacking, leading to significant discrepancies in numerical and semi-empirical models.
• Understanding extreme near-field blast pressures is vital for validating complex physics-based models and developing effective mitigation strategies.

Purpose of the Study:

• To present the design and capabilities of a novel experimental facility for measuring blast wave pressures in the extreme near field.
• To provide definitive, high-resolution spatial and temporal reflected pressure data in the extreme near field (Z<0.5 m/kg1/3).
• To enhance the understanding of blast loadings for improved design of protective structures and mitigation methods.

Main Methods:

• Design and implementation of the Mechanisms and Characterisation of Explosions (MaCE) facility, an evolution of the Characterisation of Blast Loading (CoBL) facility.
• Utilisation of an array of Hopkinson pressure bars embedded in a stiff target plate, employing maraging steel for enhanced measurement capacity (up to 1800 MPa).
• Improved spatial resolution (12.5 mm) using 33 pressure bars in a radial grid and reduced pressure bar diameter (4 mm) to minimize stress wave dispersion and increase bandwidth for observing high-frequency transient effects.

Main Results:

• The MaCE facility is designed to provide spatially and temporally resolved reflected pressure data in the extreme near field.
• Enhanced measurement capacity and spatial resolution significantly improve the fidelity of near-field blast pressure data compared to previous facilities.
• Reduced pressure bar diameter increases the effective bandwidth, enabling the capture of high-frequency transient phenomena crucial for model validation.

Conclusions:

• The MaCE facility provides a unique capability for obtaining definitive near-field blast pressure data.
• This data is essential for validating physics-based numerical models and refining semi-empirical engineering models of blast loadings.
• Improved understanding of near-field blast dynamics will directly contribute to the development of more effective blast-resistant structures and protective systems.