Overview
Flame stabilization, local weakening of reactions and particle formation depend closely on nonuniform temperature, species and flow fields. Hydrogen–ammonia combustion, turbulent mixing and sprays also involve rapidly evolving reaction zones and structures across scales. We use nonintrusive optical measurements to locate and track these processes, providing experimental evidence for combustion mechanisms, fuel comparisons and model validation. Each diagnostic is designed around a specific scientific question, considering optical access, time response and the physical meaning of the signal.
Laser absorption spectroscopy (LAS) is the optical diagnostic in which our laboratory has the most extensive research experience. Our work on quantitative temperature and species measurements includes mid-infrared absorption tomography, reconstruction of nonuniform thermochemical fields, and spatially and temporally resolved thermometry. These studies are complemented by two-dimensional soot and temperature imaging and PIV measurements in unsteady counterflow flames. Alongside LAS, our facilities support laser-induced fluorescence (LIF), laser-induced incandescence (LII), particle image velocimetry (PIV) and phase Doppler particle analysis (PDPA), with tunable dye lasers, a Princeton Instruments PI-MAX4 intensified camera and high-speed imaging. Together, these complementary methods support temperature and species measurements, reaction-zone imaging, and flow and particle diagnostics.
Future directions
Future research will extend temporal resolution and spatial coverage in swirling combustion, low-carbon fuels and reaction environments closer to practical equipment. We plan to explore synchronized diagnostics, multiple viewing angles and three-dimensional reconstruction, including spatiotemporal registration and complementary signals. Physical constraints and data-based methods will help improve reconstruction. Comparable temperature, species, particle and velocity datasets will provide a broader basis for validating complex reacting-flow models and improving combustion design.
