Three-dimensional combined pyrometric sizing and velocimetry of combusting coal particles I Velocimetry

Knowledge of the in situ temperature, size, velocity, and number density of a population of burning coal particles yields insight into the chemical and aerodynamic behavior of a pulverized-coal flame, e.g., through means of combustion model validation. Sophisticated and reasonably accurate methods are available for the simultaneous measurement of particle velocity and temperature; however, these methods typically produce single particle measurements in small analyzed volumes and require extensive instrumentation. We present a simple and inexpensive method for the simultaneous, in situ, three-dimensional (3D) measurement of particle velocity, number density, size, and temperature. The proposed method utilizes a combination of stereo imaging, 3D reconstruction, multicolor pyrometry, and digital image processing techniques. The details of theoretical and algorithmic backgrounds are presented, along with examples and validation experiments. By utilizing numerical simulations, rigorous uncertainty quantification is performed in order to estimate the accuracy of the method and explore how different parameters affect measurement uncertainty. The method is described in two parts. The first part, presented in this paper, describes particle velocity and population density mapping by stereo streaking velocimetry using overexposed emission images.