Computational Modeling of MEMS Microjets for Turbulent Boundary Layer Control

摘要

As a three year continuation of our earlier AFOSR work, we examine novel MEMS actuators for turbulent boundary layer control. The devices of interest are small and closely spaced and hence require detailed direct numerical simulation of the near surface flow to capture the physics. The devices we examine in most detail are arrays of discrete wall-normal jets to test a practical implementation of the opposition control schemes already shown to produce large drag reductions. We also performed some simple experiments examining pairs of small suction holes used to generate hairpin vortices. While the actuators are examined for their potential application for drag reduction, the emphasis of the work is more on studying the fundamental nature of the flows generated by such devices and how such small scale flows interact with the turbulent vortex structures in a wall-bounded flow. In this final report we emphasize results from simulations of arrays of 3-D slot-jet actuators triggered by practical wall-mounted sensors. Time averaged data show how the jet arrays affect the mean shear stress distribution over the controlled surface while instantaneous data show the interactions of the three-dimensional structures in detail.