MODELING OF ROTORCRAFT AND SHIP DYNAMIC INTERFACE

U.S. NAVY ROTORCRAFT HAVE THE UNIQUE PROBLEM OF MANEUVERING FOR SAFE LANDING ONBOARD SHIPS THAT ARE ROLLING, PITCHING, AND HEAVING (DEPENDING ON THE SHIP, ITS HEADING, AND THE SEA STATE) . THIS TWO-BODY DYNAMIC SITUATION IS FURTHER COMPLICATED BY THE AERODYNAMIC WAKES GENERATED FROM THE SHIP-S DECK AND SUPERSTRUCTURE. TO INSURE THE COMPATIBILITY OF A PARTICULAR ROTORCRAFT AND SHIP UNDER VARIOUS OPERATINGCONDITIONS (I.E., SEA STATE, WIND OVER DECK (WOD), AND WEATHER), THENAVY PERFORMS DYNAMIC INTERFACE (DI) TESTING USING FLEET ROTORCRAFT AND VARIOUS SHIPS OF OPPORTUNITY. THIS IS A COSTLY APPROACH AND IS SEVERELY LIMITED BY THE AVAILABILITY OF FLEET ASSETS AND THE WEATHER.THERE IS A NEED TO PERFORM A GREATER PORTION OF DI EVALUATION IN THELABORATORY AND TO RELY ON ACTUAL TESTING FOR VERIFICATION AND TRAINING. PAST EFFORTS TO SIMULATE THE AIRWAKE ENVIRONMENT THROUGH SCALE-MODEL WIND TUNNEL TESTING HAVE CORRECTLY MODELED THE STEADY WINDS AROUND THE SHIP BUT PRODUCED QUESTIONABLE RESULTS WITH RESPECT TO SHIP-INDUCED TURBULENCE. RECENT ADVANCES IN THE FIELD OF COMPUTATIONAL FLUID DYNAMICS (CFD) NOW MAKE IT POSSIBLE TO MODEL THE FULL-SCALEFLOW FIELD AROUND THE SHIP, INCLUDING TURBULENCE, EVEN FOR THE TWO-BODY PROBLEM OF A ROTORCRAFT LANDING ON A SHIP. SUCH CFD MODELS CAN BE USED TO SHOW THE EFFECTS OF SCALE ON TURBULENCE AND THEREBY TO CORRECT CURRENTLY DEFICIENT UIODEL-SCALE DATA. THE RESULTS OF THE WORK PROPOSED HEREIN WILL HE A COMPUTATIONAL PROCEDURE FOR SYNTHESIZING A SHIP-CORRELATED DYNAMIC MODEL OF AIRWAKE DISTURBANCES AND INTERFACING IT AERODYNAMICALLY WITH A ROTORCRAFT MODEL THAT IS CAPABLE OF REAL-TIME SIMULATION OF A SPECIFIC EXAMPLE OF DYNAMIC INTERFACE TESTING. THE PHASE I STUDY WILL IDENTIFY SPECIFIC COMPUTATIONAL UIETHODOLOGIESFOR MODELING THE DYNAMICS OF THE TWO BODIES AND THE ASSOCIATED AERODYNAMICS, WITH SUFFICIENT DATA TO DEMONSTRATE ITS FEASIBILITY. PHASE II WILL DEVELOP A COMPUTER CODE THAT CAN SIMULATE THIS ENVIRONMENT FOR SPECIFIC COMBINATIONS OF SHIPS, ROTORCRAFT, SEA STATE, AND WIND OVER DECK.