Date of Award

Summer 1997

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical & Aerospace Engineering

Program/Concentration

Mechanical Engineering

Committee Director

Surendra N. Tiwari

Committee Member

Sushil K. Chaturvedi

Committee Member

Ayodeji O. Demuren

Committee Member

Arthur C. Taylor

Call Number for Print

Special Collections; LD4331.E56 A78

Abstract

Extensive work in the field of drag reduction has been done in the past. However, this field of study is highly desirable today because of various high-speed research programs. The present study attempts to investigate the feasibility of drag reduction on a cylinder by flow injection from the rear stagnation region. A two-dimensional circular cylinder at Reynolds number l x105with a jet ejected from its tail is selected as a physical model. To tackle this problem, a numerical simulation as well as an experimental approach were used. Despite the recent development of computational fluid dynamics (CFD), computing a flow around a cylinder at a high Reynolds number is still difficult and expensive because of the massive separated region. A commercial CFD code was used in the present study after the various validations and sensitive analyses were performed. Full Navier-Stokes equations were solved in this code by the finite volume method and SIMPLE algorithm. To maximize the advantage of the implicit scheme used in the CFD code and to reduce the computational time, the computation was made under the steady­ state assumption. On the other hand, a static pressure measurement and a smoke wire visualization were conducted to observe the effect of the jet experimentally. It is found that the drag can be reduced by relatively small amount of the jet ejection. When the drag is decreased the pressure in the downstream portion of the cylinder is increased. This augmentation extends from the rear stagnation point to about ±120 ° where the minimum pressure is observed, while the jet has little effect on the front portion of the cylinder. It is also found that the flow behind the cylinder becomes rather symmetric when the drag reduction is being made. The numerical results show the same trend and reinforce the experimental results.

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DOI

10.25777/2j3x-7g59

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