Detailed Analysis of the Velocity Fields from 60 kW Swirl-Stabilized Coal Flames in CO_2/O_2- and N_2/O_2-Atmospheres by Means of Laser Doppler Velocimetry and Particle Image Velocimetry

摘要

This work presents experimental results from flow field measurements of swirl stabilized pulverized-coal flames in oxy-fuel conditions and in conventional atmospheres to characterize the influence of the mixture upon flame aerodynamics. Experiments were carried out on flames inside a cylindrical combustion chamber equipped with a pulverized-coal swirl burner. Flow fields for different flame configurations were measured by means of laser Doppler velocimetry (LDV) and are complemented by particle image velocimetry (PIV). The experimental setups and results are presented, compared, and discussed. LDV measurements provide radial profiles for mean and RMS axial and tangential velocity components at different cross sections inside the combustion chamber. PIV measurements provide planar two-dimensional flow field information about mean values for the axial and the radial velocity components of the flow, as well as qualitative information about solid particle distribution inside the combustion chamber. The performance of LDV and PIV as optical measurement techniques is evaluated for the present case. Coal particles with a wide size distribution are used as flow tracers in the experiments. The influences of particle size upon obtained results, the measured flow fields, and qualitative particle distributions are discussed in detail.