Question

A given flow can be laminar all over an airfoil in a real case. Select the correct statement for the assumption given above.

(a) Always true

(b) Always false

(c) True only for symmetric airfoils

(d) Depends on the Reynolds number

I have been asked this question in final exam.

This key question is from Turbulent Flow topic in section Incompressible Flow over Airfoils of Aerodynamics

Answer 1

Right answer is (b) Always false

The best explanation: The boundary layer over any body has both laminar and turbulent parts. For an airfoil, the flow encounters laminar skin- friction when it starts near the leading edge and there’s a transition to turbulent skin- friction near the trailing edge in real cases. In ideal cases, we sometimes assume a fully laminar or turbulent flow depending on the Reynolds number.