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

Abstract

Directnumericalsimulationhasbeencarriedoutforturbulentè owoverarectangulartrailingedgeataReynolds number of 1 ££ 103 (based on the freestream quantities and the trailing-edge thickness ) and ratio of boundary- layer displacement thickness to trailing-edge thickness close to unity. Two types of è ow control were studied: base transpiration and secondary splitter plate. Simulation of base transpiration was performed using different slit heights and volume è ow rates. It was found that even small è ow rates could produce signié cant changes in overall aerodynamic performance, measured, for example, by the base pressure coefé cient. It was also found that for the same volume è ow rate, a greater increase in base pressure (drag reduction ) was obtained by blowing slowly through a wide slitratherthan quickly through a narrowslit. Theeffectivenessof a secondary splitterplatelocated on the trailing-edge centerline was investigated by varying the plate length from one to é ve times the trailing-edge thickness. A signié cant increase in the base pressure coefé cient (about25%) was achieved, even with the shortest splitter plate equal to the trailing-edge thickness. The base pressure coefé cient increased monotonically with the splitter plate length, and no intermediate maximum value was found. = length of secondary splitter plate n = current time step p = instantaneous pressure pb = base pressure pref = reference pressure qb = base volume è ow rate Reh = Reynolds number based on freestream velocity and trailing-edge thickness Re±¤ = Reynolds number based on freestream velocity and displacement thickness t