ADVANCED PROPELLER BLADE SECTIONS

IT IS PROPOSED TO INVESTIGATE AND DEVELOP INNOVATIVE PROPELLER BLADE SECTION GEOMETRY WHICH WILL RESULT IN IMPROVED ACOUSTIC AND POWERING PERFORMANCE OF SURFACE SHIPS THROUGH THE ATTAINMENT OF HIGHER CAVITATION INCEPTION SPEEDS AND REDUCE BLADE DRAG. THESE SECTIONS ARE CHARACTERIZED BY A BLUNT TRAILING EDGE WITH A SEPARATED, NONCAVITATING WAKE. THE EFFECT OF THE BLUNT TRAILING EDGE, WHEN COUPLED WITH AN APPROPRIATE SECTION PROFILE, IS TWOFOLD: 1) THE LOW PRESSURE ON THE BLADE SURFACE IS RELIEVED WHICH RESULTS IN A DELAY OF THE ONSET OF CAVITATION; 2) THE THICKENED TRAILING EDGE INCREASES THE SECTION MODULUS WHICH CAN LEAD TO A REDUCTION IN DRAG FOR A GIVEN STRENGTH REQUIREMENT. THE PROPOSED PHASE I WORK IS DIVIDED INTO TWO TASKS: TASK 1 WILL BE DIRECTED TO EXPLORATORY DEVELOPMENT THROUGH PARAMETRIC STUDIES AIMED AT DETERMINING THE MOST SUITABLE PROFILES WITH REGARD TO CAVITATION INCEPTION, STRENGTH, AND DRAG. THIS DATA WILL BE ANALUZED TO IDENTIFY DESIRABLE FOIL CHARACTERISTICS AND TRENDS. TASK 2 WILL QUANTIFY THE POTENTIAL GAINS IN EFFICIENCY AND/OR CAVITATION INCEPTION SPEED IN ACTUAL SHIP APPLICATIONS. IT IS PROPOSED TO CARRY OUT DESIGN STUDIES FOR TWO REPRESENTATIVE NAVY SHIPS WHICH PROVIDE AN ESTABLISHED BASELINE. WE HAVE TENTATIVELY SELECTED THE AO 177 AS REPRESENTATIVE OF A MODERATE SPEED AUXILLARY, AND THE DDG 51 FLIGHT III AS REPRESENTATIVE OF A MODERN COMBATANT.