Investigation of drag reduction on a two-dimensional circular cylinder by ejecting a jet from the rear stagnation region

Abstract

Numerical and experimental studies were conducted to determine the feasibility of drag reduction through blowing from the rear stagnation region. The physical model was a two dimensional circular cylinder with a jet ejected from its tail. The Reynolds number based on diameter was 1x10 for the numerical simulation as well as experimental study. Static pressures were measured and a smoke wire was used to visualize the effect of the jet on the flow field. Both numerical simulations and experimental results show that relatively small amounts of the jet decrease drag. With decrease in drag, the separation points move downstream and the pressure in the base of the cylinder increases. The flow structure behind the cylinder is seen to become rather symmetric when drag reduction occurs. NOMENCLATURE a convection/diffusion coefficient Cp pressure coefficient CD drag coefficient CL lift coefficient C blowing-jet momentum coefficient d cylinder diameter 'Graduate Research Assistant, Department of Mechanical Engineering, Old Dominion University, Now Senior Engineer, adapco, LTD., 60 Broadhollow Rd., Melville, NY 11747, Member, AIAA. . Eminet Professor, Department of Mechanical Engineering, Old Dominion University, AIAA Associate Fellow. PrincipaI Engineer, Innovative Aerodynamic Technologies, Poquoson, VA 23662. Now Ph.D. Candidate, Department of Mechanical Engineering, Old Dominion University, Member, AIAA. Copyright C 1998 by the American Institute of Aeronautics and Astronautics. p pressure q dynamic pressure (-pw^) u streamwise velocity v normal velocity w siit J sht width bCp uncertainty of pressure coefficient 9 angle from the front stagnation point [Rad] a standard deviation ()> general field property function Subscript / friction / jet condition P cell center oo freestream