Circulation control: A comparative study of experimental and numerical investigation

Abstract

Circulation Control is an aerodynamic method in which the Coanda effect is induced in specific sections of the airfoil, typically near the trailing edge on the suction side in such away that, the aerodynamic properties of an airfoil are improved. Although the Coanda effect was discovered in the 1930s, research on Circulation Control can be tracked to the 1960s. The bases for Circulation Control technology are mainly empirical given by: the experiments performed in those days, the use of aerodynamic tools and the use of numerical methods. Since its discovery, this technology has not been used widely but nowadays it is thought that it is mature enough to be applied to the next generation aircrafts. As an example, the goal of some NASA Subsonic Fixed Wing projects such as the Cruise Efficient Short Take Off and Landing program (Couluris et al. 2010), is to apply this technology to design aircrafts that can take-off in much smaller distances than the typical airport runway. The key for the development of this technology is the understanding, simulation and control of the flowfield around the airfoil; for this purpose physical experiments are required for validation of numerical methods and such methods will be used then for design purposes. On the other hand, various numerical methods lead to different ranges of uncertainty in the flowfield simulation. This article presents a review of the state of the art on circulation control research, a comparative study of articles from the 1960s to 2014 of different physical experiments, numerical methods, simulations of the Coanda effect and Circulation Control and its results. Finally, the conclusion of the work is a complete vision of the usage of the analyzed techniques in future applications.