A new approach to characterize firebrand showers using advanced 3D imaging techniques

Area of Science:

• Fire Science
• Fluid Dynamics
• Imaging Technology

Background:

• Wildland-Urban Interface (WUI) fires pose significant risks due to airborne firebrands.
• Accurate characterization of firebrand behavior is crucial for predicting fire spread and mitigating damage.
• Existing methods for firebrand analysis have limitations in capturing their full 3D nature and dynamics.

Purpose of the Study:

• To introduce a novel, field-deployable diagnostic tool for characterizing airborne firebrands.
• To enable simultaneous measurement of time-resolved firebrand fluxes and 3D size distributions.
• To provide a comprehensive understanding of firebrand transport and exposure in WUI fire scenarios.

Main Methods:

• Integration of 3D Particle Tracking Velocimetry (3D-PTV) for trajectory mapping.
• Incorporation of 3D Particle Shape Reconstruction (3D-PSR) using the Visual Hull principle.
• Development of a novel graphic representation for Cumulative Particle Count (CPC) and Particle Number Flux (PNF).

Main Results:

• Successful application of the diagnostic tool to an artificially generated firebrand shower.
• Demonstration of simultaneous measurement of 3D firebrand trajectories, fluxes, and size distributions.
• Comparison of airborne firebrand size distributions with ground collection data, highlighting the tool's capabilities.

Conclusions:

• The developed diagnostic tool offers unprecedented capabilities for studying airborne firebrands in 3D.
• This technology advances the assessment of firebrand exposure metrics (CPC, PNF) relevant to WUI fire safety.
• Further refinements to the particle shape reconstruction method are proposed for enhanced accuracy.