The Application of Optimal Control to Boundary Layer Flow

摘要

Modern optimal control theory can be used to calculate the optimal steady suction needed to e.g. relaminarize the flow or to delay transition. This has been used to devise the best possible suction distributions for keeping the flow laminar, and applied for flat plate boundary layers as well as boundary layers on swept wings of airplanes. Optimal control theory can also be used to device the best possible measurement feedback control. Real time measurements of flow quantities at the wall is fed back to control the flow through wall actuation, using e.g. blowing and suction. We have applied modern control theory to channel flows as well as two-and three-dimensional boundary layers, and found that flow disturbances can be cancelled, transition delayed and low Reynolds number turbulence relaminarized.