Actual problems of the subsonic flows aerodynamics

(prospects of shear flows control)

A.V.Boiko, A.V.Dovgal, V.V.Kozlov

Institute of Theoretical and Applied Mechanics

Siberian Branch of the Russian Academy of Science

Novosibirsk, Russia

Scientific problems related to modern aeronautical engineering and dealing with basic properties of shear flows and the associated fluid mechanics phenomena are emphasized. In this context some recent experimental results on subsonic aerodynamics are considered.

Optimization of aerodynamics of modern and perspective air vehicles needs the solution of several fluid mechanics problems. They are related to studying the flow phenomena occurring close to a body surface with further elaboration of new methods to control local and global flow characteristics. As a result, it becomes possible to increase lift of wings, reduce drag of the vehicles and their acoustic radiation. As a whole, flow control is aimed at improvement of economy and operational functionality of air vehicles of different destination.

A phenomenon which is crucial for the near-wall flow pattern is hydrodynamic instability one can observe in two- and three-dimensional attached and separated boundary layers. Amplification of the laminar flow disturbances results, finally, in transition to turbulence, generation of vortex structures close to the body surface, and has a strong effect on formation of separated flow regions.

Thus, solution of the aerodynamic problems is integrated to studying various aspects of flow instability. In what follows, exploration results obtained recently on this topic are discussed from the standpoint of the main, by the author sight, problems of fluid mechanics involved in progress of commercial aviation. Most likely, perfection of the existing methods of jets control and elaboration of perspective ones are related to oncoming studies on origination and dynamics of the vortex structures dominating the perturbed flow pattern.