Effects of Multiple Cylinders on the Formation of Von Karman Vortex Streets.

This study investigated the effect of multiple cylinders positioned within 6 diameters on the formation of von Karman vortex streets. This research used a water tunnel and a modified free jet to create desired flow conditions. Both flow visualization and hot film data were obtained under various conditions. Circular cylinders were used as models for the creation of the vortex street. A water table was modified into a water tunnel which was run at various flow velocities to produce flow conditions at Re sub D or 10,000. Shadowgraph-type photos were taken of the water flow field. A free jet was run at various flow velocities to produce flow condition at a higher at Re sub D. A diverging dead-wake pattern was created by .794 cm diameter rods placed at the exit of a 1 cm by 10 cm free jet at M .1 and .6. Classical vortex streets were created using the same size cylinder and a 5 cm by 5 cm free jet nozzle with an attached channel. Both schlieren photographs and hot film measurements were taken of the flow fields at Re sub D 110,000 and 18,800 respectively. Water tunnel results indicate the formation of the von Karman vortex street has no dependence on either the absence or presence of other cylinders.