IMPROVED ALGORITHMS FOR ANALYSIS OF CIRCULATION CONTROL ROTORS

SUBSONIC AND TRANSONIC AERODYNAMIC ANALYSIS PROCEDURES HAVE BEEN DEVELOPED FOR APPLICATION TO CIRCULATION CONTROL AIRFOILS. WHILE THESE METHODS PERFORM WELL IN COMPARISON WITH EXPERIMENTS FOR LOW BLOWING COEFFICIENTS, AT HIGH BLOWING COEFFICIENTS, WITH THE NOZZLES CHOKED AND PRODUCING UNDEREXPANDED SUPERSONIC JETS, THE RESULTING SHOCK CELL STRUCTURE CANNOT BE PREDICTED BY THE PRESENT ANALYSES. A SECOND LIMITATION OF PRESENT PROGRAMS RESULTS FROM THE WAY IN WHICH NORMAL PRESSURE GRADIENT EFFECTS ARE MODELED. THE SEMI-EMPIRICAL APPROACH IS NOT SUFFICIENTLY SENSITIVE TO DETECT CHANGES IN PRESSURE DISTRIBUTIONS ARISING FROM SMALL CHANGES IN GEOMETRY. WITH THE X-WING, STOPPABLE-ROTOR AIRCRAFT IN AN ADVANCED STAGE OF DEVELOPMENT, AND WITH OTHERAPPLICATIONS OF CIRCULATION CONTROL UNDER CONSIDERATION THERE EXISTS A NEED FOR AN IMPROVED VERSION OF THE ANALYSIS METHODS. THE OBJECTIVE OF THIS EFFORT IS TO EVALUATE NEW COMPONENT METHODS AND COUPLING PROCEDURES THAT WOULD ELIMINATE THE SHORTCOMINGS OF THE EXISTING CODE. INCORPORATION OF THESE PROCEDURES IN THE TRANSONIC VISCOUS/INVISCID CIRCULATION CONROL AIRFOIL CODE WOULD THEN BEGIN.