Active flow control for high lift with steady blowing

Abstract

The general picture of research in active flow control for aircraft applications has been continuously changing over the last 20 years. Researchers can now obtain design sensitivities by using numerical flow simulations, and new optical experimental methods can be used that measure flow field data non-intrusively in planes and volumes. These methodological advances enabled significant knowledge increase. The present paper reviews recent progress in active flow control by steady blowing. It appears that two strategies of blowing deserve particular attention. The first uses tangential blowing of thin wall jets to overcome the adverse pressure gradients from locally very large flow turning rates. This approach exploits the potentials of the Coanda effect. The second strategy employs oblique blowing of air jets designed to generate longitudinal vortices in the boundary layer. The longitudinal vortices provide convective redistribution of momentum in the boundary layer, and they also enhance turbulent momentum transport. The sensitivities of these two approaches as observed in fundamental flow investigations and in applications to high-lift aerofoils are described and suited efficiency parameters of blowing are analysed.

Adaptive Nonlinear Flight Control of STOL-Aircraft Based on Incremental Nonlinear Dynamic Inversion

“…As a consequence, a nonlinear controller stabilizing this instability is essential. The latter and other aerodynamic effects were previously researched [1,[5][6][7][8] and are briefly presented in section III.…”

A New VTOL Propelled Wing for Flying Cars: Critical Bibliographic Analysis

“…Radelspiel [50] has developed an important variable geometry wing jet discharge concept that uses tangential blowing of thin wall jets to overcome the adverse pressure gradients from locally very large flow turning rates increasing the Coandă effect. It also uses oblique blowing of air jets to generate longitudinal vortices in the boundary layer and to provide a convective redistribution of momentum in the boundary layer with an increase of turbulent momentum transport.…”

The application of passive air jet vortex-generators to stall suppression on wind turbine blades

“…Various flow control methods that aim to re‐energize tired boundary layers and thereby suppress flow separation have been successfully developed. These include techniques such as vane vortex‐generators, steady air jet blowing, pulsed blowing and synthetic jets and acoustic excitation . The technique of intensifying the fluid mixing rates by the artificial formation of boundary layer‐embedded longitudinal vortices has been found to be a particularly powerful method.…”