W. Müller, M. Kloker, H. Bestek

The effect of local suction on laminar-turbulent transition phenomena in flat-plate boundary layers with streamwise pressure gradient is investigated by direct numerical simulation using the complete Navier-Stokes equations for 3-D incompressible flows. The numerical method allows for simulations of spatially growing 3-D disturbance waves in a 2-D growing boundary layer. The integration domain is located downstream of the leading edge of the flat plate. First, the 2-D steady base flow is calculated, i.e. a boundary layer with strong adverse pressure gradient affected by suction through a discrete porous strip. Then, 2-D and 3-D disturbance waves are introduced into the domain within a narrow disturbance strip located upstream of the suction strip, and their spatial linear and nonlinear evolution is calculated by numerical integration of the Navier-Stokes equations. In this paper, results from simulations for a Falkner-Skan-type boundary layer with strong adverse pressure gradient (BFs = -0.18) are presented. The effect of a suction strip on the 3-D subharmonic development in the transition process is investigated for two different streamwise positions of the suction strip. It was found that early suction can considerably delay transition even in flows with strong adverse pressure gradient, while late suction cannot prevent the nonlinear 3-D disturbance development. A simulation of the steady mean-flow over a NACA 642-A-215 airfoil with distributed suction compared well with experimental results and demonstrates that the numerical method may also be applied for flows of practical interest.

First European Forum on Laminar Flow Technology, Hamburg, 1992

Conference Paper

englisch

21,0 x 29,7 cm, 8 Seiten

DGLR-Bericht, 1992, 1992-06, First European Forum on Laminar Flow Technology; S.59-66; 1992; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

aerodynamics, laminar flow, turbulent flow

Bestellbar

1992