NASA 1996 SBIR Phase I

PROJECT TITLE : Closed Loop Flow Control System for Improved High Angle-of-Attack Maneuverability (7117-070)

TECHNICAL ABSTRACT (LIMIT 200 WORDS)

A program for the development of a closed-loop system for controlling transient separation and unsteady lift during high angle-of-attack maneuvers is proposed. The system utilizes an array of pulsed jet actuators near the airfoil leading edge. The control system will be developed and tested on a swept-wing model mounted in a low-speed subsonic wind tunnel at Physical Sciences Inc. The ability to control dynamic lift characteristics of a pitching wing will be evaluated in open-loop experiments. Surface pressure profile histories will be measured using conditional sampling and evaluated to identify appropriate control sensor positions. A closed-loop controller will be implemented on a high-speed digital signal processor and evaluated on-line for its ability to maximize unsteady lift during pitch-up. The experimental results will be used as guidelines for the design of a Phase II prototype control system for large-scale testing at flight conditions.

The development of a closed-loop system for controlling unsteady lift at high angle-of-attack will lead to improved performance and maneuverability for advanced aircraft. In addition, the control system could be used for controlling dynamic stall on helicopter rotors. It is anticipated that both commercial and military aircraft would benefit from an active control system for lift control due to its potential impact on improving lift/drag ratios and avoiding stall.

Dr. Keith R. McManus
Physical Sciences Inc.
20 New England Business Center
Andover, MA 01810-1077