Aerodynamics of Vehicles and Airplanes, and Hydrodynamics of Ships - Decreasing Fuel Consumption and Exhaust Gas Emissions in Transportation - page 109

smooth
surface

wingtip device

laminar wing

riblets

laminar fin

integrated
design

laminar horizontal
tail fin

variable
chamber

engine installation
PAI (CFD design)

rear fuselage

PAI - Propulsion Airframe Integration CFD - Computational Fluid Dynamics

Fig. 7.3 Main elements of airplanes with laminar flow

wing profiles regulated by high capacity micro controllers, fast sensors, and high
speed actuators.

7.2.1 Laminar Flow

The drag depends particularly on the shape and on the surface of the airplane's
body. Smooth laminar flow over the body produces less drag than turbulent flow.
Current aircraft design generally produces turbulent flow. Slotted airfoils or
actively heated, and cooled surfaces that encourage laminar flow are being
explored, but their benefits still need to be proven [ 6 ].
If wing-mounted propfans and un-ducted fans are increasingly used in the
future laminar flow airfoils that could tolerate the effects of propeller efflux over
the wing surface also need to be developed. Alternative mounting arrangements,
such as fuselage-mounted propfans may also be considered; see Fig. 7.3 [ 7 ].
Laminar flow without turbulence for wings, fuselage, stabilizers and nacelles is
continuously reviewed and evaluated. Besides technology, the key consideration is
the cost of laminar flow systems and their power requirements compared with
savings obtained through drag reduction.

7.2.2 Nacelle Efficiency

Suboptimal integration of the engine and the nacelle which does not incorporate
the air inlet can be a source of significant drag. Effective nacelle-oriented wing and
tail constructions reduce turbulent flow areas [ 8 ]. The effect can be supported
through the use of advanced passive flow control devices, e.g., vortex generators to