Effect of Rotating Cylinder at Variable Location to Control Base Flows at Mach 2

The effect of the cylinder being turned counter-clockwise inside the dead zone at different positions near its base to adjust base pressure for varying levels of expansion for area ratio 9 has been investigated experimentally. When viewed from the top, a 2 mm diameter cylinder moving counter-clockwise is placed as a controller. To attach the controller, three positions are chosen from the square duct sidewall, namely 2, 4, and 6 mm, respectively, and one from the square nozzle exit, namely 8 mm in the base region. With and without control, base pressure in the recirculation zone and wall pressure along the square duct length were monitored. For NPR 2, 3, 6, 7.8, and 8.5, the trials were conducted at Mach 2. The base drag was reduced by 62 percent when the cylinder was rotated counter-clockwise as an active controller near the duct wall and 50 percent when it was spun clockwise as an active controller distant from the duct wall for the same NPR. The reduction in base drag at the duct wall for perfectly expanded flows at NPR 7.8 ranged from 44 to 53 percent, depending on the location of the controller. For over-expanded flows near the duct wall, the active controller was up to 19% effective, and for over-expanded flows away from the duct wall, it was up to 12 percent effective. The base drag reduction was between 49 and 64 percent for under expanded flows at NPR 8.5, depending on the placement of the controller. Furthermore, the control had no negative impact on the flow field. A shadowgraph was used to record additional flow visualisation inside the duct.

Author(s) Details

Mohammed Asadullah
Department of Mechanical Engineering, Lords Institute of Engineering & Technology, Hyderabad, India.

S. A. Khan
Department of Mechanical Engineering, International Islamic University Malaysia, Kuala Lumpur, Malaysia.

Waqar Asrar
Department of Mechanical Engineering, International Islamic University Malaysia, Kuala Lumpur, Malaysia.

E. Sulaeman
Department of Mechanical Engineering, International Islamic University Malaysia, Kuala Lumpur, Malaysia.

Syed Azam Pasha Quadri
Department of Mechanical Engineering, Lords Institute of Engineering & Technology, Hyderabad, India.

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