Transition flight experiments on a swept wing with suction

Abstract

Flight boundary-layer transition experiments were conducted on a 30 degree swept wing with a perforated leading-edge suction panel. The transition location on the panel wm changed by systematically varying the location and amount of suction. Transition from laminar to turbulent flow was due to leading-edge turbulence contamination or crossflow disturbance growth and/or Tollmien-Schlichting disturbance growth-depending on flight condition and suction variation. Amplification factor correlations with transition location were made for various suction configurations using a state-of-the-art linear stability theory which accounts for body and streamline curvature and compressibility.

Simulation of nonlinear instabilities in an attachment-line boundary layer

“…If the Reynolds number of the attachment-line boundary layer is greater than some critical value, then this contamination inevitably leads to turbulent ow over the complete wing; this phenomenon has been demonstrated by Maddalon et al (1990) and others. To correct this problem, Gaster (1965) placed a bump on the leading edge to prevent the turbulent attachment-line boundary layer from sweeping over the entire wing.…”

A reduced-order approach for optimal control of fluids using proper orthogonal decomposition

“…First M 'snapshots' were recorded at constant time intervals Dt* (= 200Dt) with a prescribed linear profile c(t)= t in the time interval [0,10]. Then the test functions were defined as follows:…”

Evolution of stationary crossflow vortices in boundary layers on swept wings

“…and boundary conditions u = 0 at y = 0 and u -» < as (3) The Reynolds number Re = 2#5/v is based on the boundary-layer thickness in the jcy plane defined as 8 = */vx c / U () (where x c is the chordwise coordinate normalized by the chord length) and the local edge velocity Q R = go at the computational inflow.…”

“…The fuel savings translates directly into reduced operating costs in terms of millions of dollars over the life of a single aircraft. 1 Improvements in wing designs 2 and the implementation of devices such as suction for laminar flow control 3 and Caster's bump 4 successfully reduce aircraft drag. These technological advances are successful because they are based (in part) on a fundamental understanding of three-dimensional boundary-layer flow physics.…”