Transition from laminar to turbulent flow around an airfoil

<p>"A computational fluid dynamics (CFD) code has been developed for two-dimensional incompressible turbulent flows and employed to solve the Navier Stokes equations around an airfoil of arbitrary shape. A low-Reynolds-number k — e turbulence model including curvature effect was used to consider the gain and loss of turbulent kinetic energy. To include laminar sublayer into the computational domain, a multi-layer grid and a cubic-slpine grid were introduced through a conservative form of coordinate transformation. The flow structure varies with the Reynolds numbers. For an airfoil at low Reynolds numbers (below ten thousand), distinct vortex shedding patterns can be found in the wake regions. The Strouhal number (vortex frequency) increases with Reynolds number. Simulation of boundary layer control (BLC) by suction on the upper surface and blowing at the trailing edge was conducted for improving aerodynamic performance. Various suction locations were investigated for an NACA 0015 airfoil at 10 deg of incidence and Reynolds numbers of 5 x 10⁴ and 5 x 10⁵. Small suction level near the leading edge has a minimal effect in improving aerodynamic performance. To avoid flow separation, high suction level is needed near the region of the trailing edge. At higher Reynolds numbers, transition from laminar to turbulent flow occurs around the airfoil. Increasing Reynolds number or angle of incidence moves the transition point further toward the leading edge. The computed velocity profiles and shear stresses are compatible with available experimental data for a Garabedian airfoil at 6 deg of incidence and an NACA 4412 airfoil at 13.87 deg of incidence with Reynolds numbers greater than 10⁶. The locations of transition, however, could not be verified because of lacking experimental data"--Abstract, p. iv</p>

Name thesis:degree_name

Ph. D. in Mechanical Engineering

Grantor

University of Missouri--Rolla

Year dc:date.available

2016

Author dc:creator

• Chen, Chang-Ren

• Mechanical Engineering

Repository record dc:identifier

https://scholarsmine.mst.edu/doctoral_dissertations/828

OAI identifier oai:identifier

oai:scholarsmine.mst.edu:doctoral_dissertations-1830