Laminar-Turbulent transition delay by means of passive control

Research Area: Fluid mechanics
Project Members:
Brandt, L.B.
Cossu, C.
Fransson, J. H. M.
Talamelli, A.
Sponsor: KTH,   VR 

Project Description

The design of wing profiles able to support a laminar boundary layer flow has been the object of many research efforts owing to the high potential benefits in term of drag reduction. We have recently found that the primary viscous linear instability of a boundary layer flow can be delayed by forcing finite amplitude spanwise modulations (streamwise streaks) of the streamwise velocity profile. We propose to evaluate the impact of this strategy on transition delay by new wind tunnel experiments. The aim of this project is to perform experiments in order to delay transition to turbulence in boundary layer flows. The MTL tunnel, which is considered to be one of the best wind tunnels in the world of its kind, will be used together with flow visualization and modern measurement techniques. The tunnel is located at KTH Mechanics and is of low speed type with a very low background disturbance level, which makes it suitable for transition studies. Control of wall-bounded transitional flows is the object of the present investigation owing to the high potential benefits. Any reduction of the skin-friction drag, for example, implies relevant savings of the operational cost of commercial aircrafts.

Publications related to the project

2006Delaying transition to turbulence by a passive mechanism
Physical Review Letters 96 064501 (Published)
2005Experimental study of the stabilization of Tollmien-Schlichting waves by finite amplitude streaks
Phys. Fluids 17 (5) 054110 (Published)
2004Experimental and theoretical investigation of the non-modal growth of steady streaks in a flat plate boundary layer
Phys. Fluids 16 3627-3638 (Published)

Internal Reports related to the project

YearTitleDocument Type