The main objective of this thesis is to study the flow characteristics of a rotary cylinder with a symmetric end plate. We performed the simulations for different velocity ratios (0, 5, 10, and 15), aspect ratios (9.053 and 18) at high Reynolds numbers (1.15 x 104 ≤ Re ≥ 6.44 x 105). We then studied the wake structure, the vortices formed in the wake region, the effect of vortex formation on the aerodynamic forces such as lift and drag. We performed computational fluid dynamics (CFD) simulations using a CFD solver, STAR-CCM+ from CD-Adapco. The results show that when the circular cylinder is stationary, the vortex shedding frequency is high; the upper and lower vortices show an asymmetrical process with the wake centerline. A significant vortex pairing can also be seen. But, with the rotation and increase in velocity ratio, the strength of vortex shedding decreases and after velocity ratio 5 the periodic vortex shedding is suppressed. The structure of the wake also modifies depending on the direction of the rotation. When aspect ratio of the circular cylinder is increased, the lift force generated on the cylinder surface is decreased. When an end plate is introduced in the region close to the stationary circular cylinder, it creates interference in the vortex formation and hence, the instabilities in the fluid flow due to vortices are decreased. The geometry of the stationary circular cylinder with an end plate seems to behave similar to a symmetric airfoil at zero angle of attack. Hence, aerodynamic forces generated on the geometry are constant. When the circular cylinder with the end plate is given a constant rotation, then the vortex formation is suppressed, the wake moves further downstream due to the end plate, the lift force generated on the surface increases and a significant decrease in drag force is also observed.
|Advisor:||Rahai, Hamid R.|
|Commitee:||Jang, Larry, Shankar, Praveen|
|School:||California State University, Long Beach|
|Department:||Mechanical and Aerospace Engineering|
|School Location:||United States -- California|
|Source:||MAI 51/05M(E), Masters Abstracts International|
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