A NOVEL POTENTIAL/VISCOUS FLOW COUPLING TECHNIQUE FOR COMPUTING HELICOPTER FLOW FIELDS

BECAUSE OF THE COMPLEXITY OF THE HELICOPTER FLOW FIELD, A ZONAL METHOD OF ANALYSIS OF COMPUTATIONAL AERODYNAMICS IS REQUIRED. IN THIS RESEARCH, A NEW PROCEDURE FOR COUPLING POTENTIAL AND VISCOUS FLOW CALCULATION SCHEMES IS PROPOSED. AN OVER-LAPPING, VELOCITY-COUPLING TECHNIQUE IS TO BE DEVELOPED WITH THE UNIQUE FEATURE THAT THE POTENTIAL FLOW SURFACE SINGULARITY STRENGTHS ARE OBTAINED DIRECTLY FROM THE NAVIER-STOKES SOLUTION AT A SMOOTHER INNER FLUID BOUNDARY. THE CLOSED-LOOP INTERATION METHOD PROCEEDS UNTIL THE VELOCITY FIELD IS CONVERGED. THIS COUPLING SHOULD PROVIDE THE MEANS OF MORE ACCURATE VISCOUS COMPUTATIONS OF THE NEAR-BODY AND ROTOR FLOW FIELDS WITH RESULTANT IMPROVED ANALYSIS OF SUCH IMPORTANT PERFORMANCE PARAMETERS AS HELICOPTER FUSELAGE DRAG AND ROTOR AIRLOADS.