Methods for obtaining simultaneous field measurements of particle and gas velocity in relatively dilute turbulent flows will be presented. These measurements allow determination of local slip velocity, particle-induced flow modification, and particle-fluid spatial correlations. Thin sheets of flow laden with smoke tracers and glass beads are illuminated with pulsed light from Nd:YAG lasers and photographed with a single digital camera (two-dimensional measurements) or a pair of cameras (stereo measurements). Custom software is applied to separate the resulting images into smoke and glass files that are processed independently. Gas velocity fields are obtained by PIV cross correlation analysis, and particle velocities are obtained either by correlations or a tracking routine. These methods have been applied in a free jet, an impinging jet, and a fully-developed turbulent channel flow. Examples of the resulting measurements will be presented. In free and impinging jets, the methods were used to document locations of high slip velocity and the extent of vortex modification by particles. In the channel flow, the measurements are applied to determine statistical correlations in homogeneous fields. Details and limitations of the separation method and subsequent analysis will be discussed, including separation strategies, uncertainty and bias due to image digitization, and limitations on volumetric loading.
|Original language||English (US)|
|Title of host publication||Proceedings of the 1999 3rd ASME/JSME Joint Fluids Engineering Conference, FEDSM'99, San Francisco, California, USA, 18-23 July 1999 (CD-ROM)|
|Publisher||American Society of Mechanical Engineers|
|Number of pages||1|
|State||Published - 1999|