Why is laminar flow preferred during flight? The answer relates to two of the four primary aerodynamic forces acting on an airfoil and the aircraft as a whole:ĭrag in the boundary layer: Once the flow crosses into the turbulent regime, fluid flow in the boundary layer becomes turbulent and creates additional drag during flight. Regardless, we would prefer the flow rate across the aircraft to always be laminar. What exactly constitutes a “low” Reynolds number depends on the shape and roughness of the wing, as is briefly discussed below. At low Reynolds number flows, the airflow is laminar and sets up a boundary layer along the surface of the wing.
BOUNDARY LAYER AIRFOIL SKIN
Thrust exerted by the aircraft can create additional lift and drag due to skin friction along the surface of the craft, and particularly along the airfoil. Why Laminar Flow Over Airfoils?ĭuring flight, airflow across the wing of an aircraft creates drag and lift. We’ll discuss these aspects of laminar flow over airfoils and examine the limits of laminar flow across airfoils in this article. The reasons for this are varied, but they relate to the main aerodynamic forces acting on an aircraft, and particularly on the airfoil itself. Together, these are the main determining factors used to design aircraft to reach engineering and performance goals once an aircraft is put into operation.ĭuring flight, an aircraft would prefer to encounter laminar flow. The flow regime is important in aircraft design and engineering, as it determines the amount of lift and drag acting on an airfoil. On an aircraft, an airfoil is the structure responsible for moderating lift and drag created by oncoming airflow. Typical laminar-to-turbulent flow transitions over airfoils occur at Reynolds numbers of approximately 500,000.Īir traffic wouldn’t be possible without laminar flow and airfoils. When airflow transitions to turbulent at high Reynolds numbers, the result is greater drag. Airflow over airfoils generates lift and drag, and the amount of lift depends on the flow regime.
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