Application of Circulation Control to Advanced Subsonic Transport Aircraft, Part I - Airfoil Development

Abstract

An experimental/ analytical research program was undertaken to develop advanced versions of circulation control wing (CCW) blown high-lift airfoils, and to address specific issues related to their application to subsonic transport aircraft. The primary goal was to determine the feasibility and potential of these pneumatic airfoils to increase high-lift system performance in the terminal area while reducing system complexity. A four-phase program was completed, including 1) experimental development and evaluation of advanced CCW high-lift configurations, 2) development of effective pneumatic leading-edge devices, 3) computational evaluation of CCW airfoil designs plus high-lift and cruise capabilities, and 4) investigation of the terminal-area performance of transport aircraft employing these airfoils. The first three phases of this program are described in Part I of this article. Applications to the high-lift and control systems of advanced subsonic transport aircraft and resulting performance are discussed in the continuation of this article, Part II. Experimental lift coefficient values approaching 8.0 at zero incidence and low blowing rates were demonstrated by two-dimensional CCW configurations that promised minimal degradation of the airfoil's performance during cruise. These results and experimental/CFD methods will be presented in greater detail in the following discussions.