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

Abstract

Direct numericalsimulationhas been carried out for turbulent flow over a rectangular trailing edge at a Reynolds number of 1x10(3) (based on the freestream quantities and the trailing-edge thickness) and ratio of boundarylayerdisplacement thickness to trailing-edge thickness close to unity. Two types of flow control were studied: base transpiration and secondary splitter plate. Simulation of base transpiration was performed using different slit heights and volume flow rates. It was found that even small flow rates could produce significant changes in overallaerodynamic performance, measured, for example, by the base pressure coefficient. It was also found that for the same volume flow rate, a greater increase in base pressure (drag reduction) was obtained by blowing slowly through a wide slit rather than quickly through a narrowslit. The effectiveness of a secondary splitter plate located on the trailing-edge centerline was investigated by varying the plate length from one to five times the trailing-edge thickness. A significant increase in the base pressure coefficient (about 25%) was achieved, even with the shortest splitter plate equal to the trailing-edge thickness. The base pressure coeffi cient increased monotonically with the splitter plate length, and no intermediate maximum value was found.