Application of Optical Diagnostics Techniques to a Laboratory-Scale Turbulent Pulverized Coal Flame

TLDR

Optical diagnostics provide noninvasive measurements of velocity, density, temperature, pressure, and species concentration, enabling clarification of combustion mechanisms and validation of computational models. This study investigates the combustion characteristics of a pulverized coal flame using advanced optical diagnostics. A laboratory‑scale pulverized coal burner was fabricated, and velocity, shape, and temperature of nonspherical particles were measured with a shadow Doppler particle analyzer, multicolor integrated receiving optics, and a two‑color radiation pyrometer, while simultaneous OH‑PLIF and Mie scattering images examined the spatial relationship between the combustion reaction zone and the particles. The SDPA accurately measured size‑classified diameter and velocity of coal particles, and the combined OH chemiluminescence, CH band emission, and simultaneous OH‑PLIF/Mie scattering measurements effectively evaluated the flame and revealed its detailed structure.

Abstract

Combustion measurements based on optical diagnostics techniques, which allow noninvasive measurements of velocity, density, temperature, pressure, and species concentration, have recently become of major interest as tools not only for clarifying the combustion mechanism but also for validating the computational results for the combustion fields. In this study, the combustion characteristics of a pulverized coal flame are investigated using advanced optical diagnostics. A laboratory-scale pulverized coal combustion burner is specially fabricated. Velocity and shape of nonspherical pulverized coal particles, light emissions from a local point, and temperature in the flame are measured by shadow Doppler particle analyzer (SDPA), a specially designed receiving optics (multicolor integrated receiving optics, MICRO), and a two-color radiation pyrometer, respectively. The simultaneous measurement of OH planar laser-induced fluorescence (OH−PLIF) and Mie scattering image of pulverized coal particles is performed to examine spatial relation of combustion reaction zone and pulverized coal particle. The results show that the size-classified diameter and velocity of the pulverized coal particles in the flame can be measured well by SDPA. The measurements of the OH chemiluminescence and CH band light emission from a local point in the flame using MICRO and the simultaneous measurement of the instantaneous OH−PLIF and Mie scattering image of pulverized coal are effective for evaluating the pulverized coal flames and investigating their detailed flame structure.