Utilizing spectroscopy to quantify Thermal transport In fLame sprEad

Introduction

Uncontrolled fire in the built and wild environment remains a major societal issue. Climate change and an increasing elderly population suggest a worsening of fire damage within the following years.

Importance of Flame Spread Rate

The flame spread rate (Vf) is the principal quantity to assess the danger of a fire. Accurately predicting thermal transport to the unburnt material is critical to predicting the Vf. Improved quantification of the modes by which flames spread can aid in the prevention and control of nonstationary fires.

Methodology

Combined simultaneous multi-dimensional temperature distributions of the gas with the condensed-phase are required to calculate heat flux to the surface. UTILE is tailored to understand flame spread (FS) by measuring heat flux with multi-dimensional ultrafast laser diagnostics.

Experimental Setup

A canonical FS configuration (flat plate) with well-known boundary conditions and optical access will be built. The following techniques will be employed:

1. Fs/ps Hybrid Rotational Coherent Anti-Stokes Raman Spectroscopy (HRCARS) for gas-phase measurements.
2. Phosphor thermometry to measure the surface temperature.
3. Particle Image Velocimetry (PIV) to measure the airflow boundary layer.
4. Chemiluminescence (CH or OH) to locate the reacting flame front.

Novel Contributions

No fire studies have used simultaneous multi-dimensional temperature measurements of the gas and condensed-phase to calculate heat flux.

UTILE is not limited to quantifying heat flux but is a platform to advance the state-of-the-art in ultrafast laser diagnostics. Pushing limitations in 2D HRCARS and ultra-broadband HCARS will decrease experimental time and increase species sensitivity to the opposed and concurrent FS studies.

Future Directions

Using multi-photon excitation for phosphor thermometry has the potential to improve multi-dimensional surface thermometry. Combining a modern experimental setup with tailored laser diagnostics will provide novel data quantifying heat flux leading to FS.

Conclusion

Improving Vf models will benefit fire safety and refine the predictability of Computational Fluid Dynamics (CFDs).