Boundary-Layer Suction System Design for Laminar-Flying-Wing Aircraft

Abstract

DOI: 10.2514/1.C031283 The present study aims to provide insight into the parameters affecting practical laminar-flow-control suction power requirements for a commercial laminar-flying-wing transport aircraft. It is shown that there is a minimum power requirement independent of the suction system design, associated with the stagnation pressure loss in the boundary layer. This requirement increases with aerofoil section thickness, but depends only weakly on Mach number and (for a thick, lightly loaded laminar flying wing) lift coefficient. Deviation from the optimal suction distribution, due to a practical chamber-based architecture, is found to have very little effect on the overall suction coefficient;hence,toagoodapproximation,thepowerpenaltyisgivenbytheproductoftheoptimalsuction flowrate coefficient and the average skin pressure drop. In the spanwise direction, through suitable choice of chamber depth, the pressure drop due to frictional and inertial effects may be rendered negligible. Finally, if there are fewer pumps than chambers, the average pressure drop from the aerofoil surface to the pump collector ducts, rather than to the chambers,determinesthepowerpenalty.Fortherepresentativelaminar-flying-wingaircraftparametersconsidered here, the minimum power associated with boundary-layer losses alone contributes some 80–90% of the total power requirement.