Showing papers by "Sreenivas Jayanti published in 2002"
••
TL;DR: In this article, a mechanically stirred eight-blade paddle impeller in an unbaffled vessel over a range of Reynolds numbers covering laminar, transitional and turbulent flow regimes is presented.
Abstract: CFD-based computations of the flow field, power consumption and mixing time are presented for a mechanically stirred eight-blade paddle impeller in an unbaffled vessel over a range of Reynolds numbers covering laminar, transitional and turbulent flow regimes. The flow field calculations were performed using the sliding mesh technique to account for the motion of the impeller, and mixing time studies were done using a simulated tracer injection experiment. The effect of grid density and the choice of the turbulence model were investigated. The results are compared with flow field data from Dong et al . 1 , and power and mixing time correlations from the literature and show satisfactory agreement. It is shown that the product of mixing time and rotational speed remains constant for paddle impellers for laminar flow and that the use of a low Reynolds number turbulence model is necessary for good prediction of mixing time in the transitional flow.
87 citations
••
TL;DR: In this article, measurements of the pressure gradient, film thickness and down flow rate were made for a range of air and water flow rates under pre- and post-flooding conditions.
14 citations
••
TL;DR: In this paper, the authors studied the post-flooding situation in air-water countercurrent flow in a tube of 0.025 m internal diameter with smooth inlet and outlet conditions for the two phases.
Abstract: Systematic experiments were conducted to study the postflooding situation in air–water countercurrent flow in a tube of 0.025 m internal diameter with smooth inlet and outlet conditions for the two phases. The downflow rate of water and the pressure gradient were measured over a range of flow rates for test-section lengths of 0.6, 1.2 and 2.0 m. Additional experiments were conducted with increasing and decreasing water flow rates at a constant air flow rate. The length of the test section or the way the flooding point was approached did not significantly affect the onset of flooding. The data show that, as the gas flow rate is increased, the pressure gradient can fall significantly in the postflooding situation due to depleting the downflow rate of liquid. Dimensionless correlations are proposed to calculate the downflow rate and the pressure gradient given for overall flow parameters.
8 citations