顺排微柱群内部层流流动特性

Laminar flow characteristics in in-line arranged micro-cylinder groups

The flow field, pressure filed and friction characteristics of laminar flow in in-line arranged micro-cylinder groups were numerically investigated using de-ionized water as working fluid at low Reynolds numbers.The friction factors in the micro-cylinder group (cylinder diameter D =0.5 mm, cylinder height H =1.00, 0.75, 0.50 and 0.25mm)were measured.It was found that the friction factor decreased with the increase of micro-cylinder height due to the end-wall effect, and the correlations available could not predict the friction characteristics very well.A 3-D model was employed to simulate the vortex distribution in the in-line micro-cylinder groups with different geometrical parameters, including the diameter (0.5 mm)and height (0.25, 0.50, 0.75, and 1.00 mm)of micro-cylinder, pitch (0.75, 1.00, and 1.25 mm), and number of rows (3, 5, 7, 9)and columns (5, 10, 15, 20)of micro-cylinder.It was found that the vortex number increased with the pitch ratio, so that the friction factor increased.The friction factor for the in-line arranged micro-cylinder group decreased with the increase of the cylinder height and the decrease of the column number, but the influence of the row number on the friction factor was negligible.A new correlation was obtained to predict the friction factor of laminar flow in the in-line arranged micro-cylinder group and the deviation of predictions from experimental results is 10%—25% at 40<Re<150.