Author's School

School of Engineering & Applied Science

Author's Department/Program

Mechanical Engineering and Materials Science


English (en)

Date of Award

January 2010

Degree Type


Degree Name

Master of Arts (MA)

Chair and Committee

Ramesh Agarwal


The fundamental effects of micro-ramp, synthetic-jet, and hybrid flow control devices are studied through the use of numerical simulations. The beneficial flow control effect is then optimized using the response surface methodology. The effectiveness of each device is judged based on how it influences the shape factor of the boundary layer far downstream of the device. The mechanism of flow control action of each device is a pair of streamwise oriented counter rotating vortices; however, the nature of the vortices produced is unique in each case. The micro-ramp reduced the shape factor by 3.31%, the synthetic-jet by 3.32%, and the hybrid device reduced the shape factor by 3.44% from the baseline. Considering a three factor face-centered central composite design, the hybrid device is optimized capitalizing on the positive effects produced by the micro-ramp and synthetic-jet individually. The deviceΓÇÖs performance is shown to be insensitive to the spacing between the micro-ramp and the synthetic-jet. There is, however, a significant sensitivity to the ratio of jet length to jet momentum coefficient. At the optimum value of this ratio: 1.33ΓÇ¥) the shape factor is decreased by 5.7%.


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