Direct Numerical Simulation of Turbulent Trailing-Edge Flow with Base Flow Control

Direct numerical simulationhas been carried out for turbulent  owovera rectangular trailing edge at aReynolds number of 1 £ £ 103 (based on the freestream quantities and the trailing-edge thickness) and ratio of boundarylayer displacement thickness to trailing-edge thickness close to unity. Two types of  ow control were studied: base transpiration and secondary splitter plate. Simulation of base transpiration was performed using different slit heights and volume  ow rates. It was found that even small  ow rates could produce signiŽ cant changes in overall aerodynamic performance, measured, for example, by the base pressure coefŽ cient. It was also found that for the same volume  ow rate, a greater increase in base pressure (drag reduction) was obtained by blowing slowly through a wide slit rather than quickly through a narrow slit. The effectiveness of a secondary splitter plate located on the trailing-edge centerline was investigated by varying the plate length from one to Ž ve times the trailing-edge thickness. A signiŽ cant increase in the base pressure coefŽ cient (about 25%) was achieved, even with the shortest splitter plate equal to the trailing-edge thickness. The base pressure coefŽ cient increased monotonically with the splitter plate length, and no intermediate maximum value was found.