Balaji Gopalan, Mehrdad Shahnam, Rupen Panday, Jonathan Tucker, Frank Shaffer, Lawrence Shadle, Joseph Mei, William Rogers, Chris Guenther, Madhava Syamlal, Measurements of pressure drop and particle velocity in a pseudo 2-D rectangular bed with Geldart Group D particles, Powder Technology, Available online 31 December 2015, ISSN 0032-5910, http://dx.doi.org/10.1016/j.powtec.2015.12.040.
Abstract: A small scale pseudo 2-D bed of dimension 0.075 m × 0.23 m × 1.22 m was utilized to measure the pressure drop and velocity statistics of Geldart Group D nylon beads. The pressure drop was measured using a fast-response pressure transducer and the particle velocities were measured with high speed particle image velocimetry, with particle tracking, in a slugging flow regime for three different superficial gas velocities (2, 3 & 4 times the minimum fluidization velocity (Umf)). At superficial gas velocity of 3 Umf, the measured slugging frequency was about 2.5 Hz, while at conditions close to 2 Umf and 4 Umf, the slugging frequency was about 1.5 and 1.7 Hz. Additionally, at 3 Umf condition, the bed exhibited a much higher root mean square (RMS) of pressure drop fluctuations than those at 2 Umf and 4 Umf. The varying trend suggested an existence of a complicated regime change for these shallow bed measurements that had not been previously explored. The measurement of millions of individual particle velocities at the vicinity of the wall had enabled accurate measurement of higher order statistics including RMS, granular temperature, skewness, and kurtosis of particle velocity. The measured skewness and kurtosis of the velocity distribution indicated that the particle velocity distribution deviated substantially from a normal distribution as the intersection of walls of the rectangular bed was approached.
Keywords: Fluidization; Granular flow; Experiment; Granular temperature; High speed PIV