THIS PROJECT INVOLVES A DESIGN STUDY AND DEVELOPMENT OF A MULTI-ELEMENT HIGH REYNOLDS NUMBER NLF AIRFOIL THAT MINIMIZES THE TURBULENT SEPARATION PROBLEM AT OFF DESIGN CONDITIONS.

THIS PROJECT INVOLVES A DESIGN STUDY AND DEVELOPMENT OF A MULTI-ELEMENT HIGH REYNOLDS NUMBER NLF AIRFOIL THAT MINIMIZES THE TURBULENT SEPARATION PROBLEM AT OFF DESIGN CONDITIONS. THE CONCEPT DEVELOPMENT WILL UTILIZE AN INTEGRATED MULTI-ELEMENT AIRFOIL SYSTEM TO BE DESIGNED TO FORM A SLOT BETWEEN THE UPPER AND LOWER SURFACE IN THE TURBULENT RECOVERY REGIONS. THIS SLOT BRINGS HIGHER ENERGY AIR FROM THE LOWER SURFACE TO RE-ENERGIZE THE TURBULENT BOUNDARY LAYER ON THE UPPER SURFACE. ALSO BECAUSE OF THE INTERACTION OF THE ELEMENTS FORMED BY THIS SLOT, THERE ARE ADDED BENEFITS IN REDUCING THE ONSET OF TURBULENT BOUNDARY LAYER SEPARATION. THE PRESSURE AT THE TRAILING EDGE OF THE MAIN ELEMENT IS REDUCED WHILE THE MAXIMUM VELOCITIES ON THE FLAP ARE REDUCED. BOTH THESE EFFECTS REDUCE THE TOTAL PRESSURE RISE IN THE RECOVERY REGIONS. THIS NEW NLF AIRFOIL IS TO BE DEVELOPED ITERATIVELY, BASED ON THE VIKEN-PFENNINGER NLF (1)-0414F AIRFOIL WITH 70% CHORD LAMINAR FLOW; USING POTENTIAL FLOW, BOUNDARY LAYER, AND LAMINAR FLOW STABILITY COMPUTER CODES. EMPHASIS WILL BE MADE TO GET EXTENSIVE LAMINAR FLOW FOR AS WIDE A LIFT RANGE AS POSSIBLE AND TO GET ACCEPTABLE ACCELERATION THRUGH THE SLOT AT NOT ONLY THE HIGH CLIMB LIFT COEFFICIENTS BUT ALSO AT THE LOW CRUISE LIFT COEFFICIENTS WHEN THERE IS VERY LITTLE PRESSURE DIFFERENCE BETWEEN THE SURFACES. LAMINAR BOUNDARY LAYER STABILITY WILL ALSO BE ANALYZED AND THE DESIGN WILL ACCOUNT FOR THE EFFECTS OF REYNOLDS NUMBER CHANGE ON THE AIRFOIL.