Understanding Blue Whirl Combustion for Fuel-Flexible Energy Extraction
Abstract
This work examines the physical underpinnings of the blue whirl: a new regime of soot-free combustion evolving naturally from fire whirls across a broad range of fuels and having potential as a fuel-flexible heat source for power generation. Experiments found blue whirl formation to depend more on fluid dynamics than chemical kinetics and requires both vortex-generating and surface airflows. Successful simulation of the blue whirl revealed a bubble-mode vortex breakdown flow structure and the presence of three distinct flame types. This structure persisted in simulations in which the flame was rotated up to 15 deg with respect to gravity, indicating dominance of rotational over axial inertial forces. An advanced experimental burner was designed and constructed, providing control over airflow rates, profiles and temperatures, fuel delivery, and burner height and diameter. Blue whirls produced with the burner could be sustained indefinitely, and flame stability with respect to radial and tangential airflow rates, fuel type, and fuel flow rates was mapped. Stable blue whirls were formed across a wide range of conditions, reaching heat release rates exceeding 750 W. Analysis found that the blue whirl resides in a non-dimensional parameter space sufficiently dominated by rotational airflow below the onset of turbulence.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2022
- Accession Number
- AD1164699
Entities
People
- Paul M. Anderson
Organizations
- United States Army