Control of Base Pressure with Variable Location of Clockwise Rotating Cylinder
7 Pages Posted: 16 Feb 2018
Date Written: December 21, 2017
The effect of cylinder when rotated clockwise inside the recirculation zone at different locations near its base to reduce base drag for over and perfectly expansion flows at Mach 2 have been experimentally investigated for area ratio 9. Dynamic cylinder of 2 mm diameter rotated clockwise when seen from top, at three locations from side wall of square duct at 2, 4, 6 mm respectively and 8 mm from square nozzle exit in the base region is mounted as a controller. Base pressure in dead zone and wall pressure along the square duct length has been measured with and without control. The experiments were carried out for NPR 2, 3, 6 and 7.8. Cylinder when rotated clockwise as an active controller was found to increase the base pressure up to 56 percent at NPR 7.8. located near to duct wall and 43 percent when located away from duct wall for the same NPR. The active controller was up to 17 percentage effective for over expanded flows near to duct wall and up to 14 percent when located away from duct wall. Also, the control does not affect the flow field in the duct. Rotating cylinder near the wall was found to be more effective for higher NPRs and that too near the wall.
Keywords: Base pressure; Wall pressure; Nozzle pressure ratio; Mach number; Active control
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