DIRECT COMPUTATION OF TURBULENCE NOISE

DIRECT COMPUTATION OF TURBULENCE NOISE IS A LOGICAL APPLICATION FOR ADVANCED COMPUTATIONAL FLUID DYNAMICS, CFD, PROGRAMS RUN ON SUPERCOMPUTERS. THIS WOULD ELIMINATE THE HIGHLY EMPIRICAL ASPECTS OF PRESENT NOISE PREDICTION TECHNIQUES AND ENABLE STUDY OF ADVANCED HYPERSONIC PROPULSION SYSTEMS. HOWEVER, MANY OF THE SAME PERSISTENT PROBLEMS OF IMPLEMENTATION THAT EXIST IN AEROACOUSTIC THEORY AND MEASUREMENT WILL ALSO PREVAIL IN A FULLY NUMERICAL APPROACH. A FUNDAMENTAL STUDY OF THE MEANS OF APPLYING CFD TECHNIQUES TO NOISE COMPUTATIONS IS THEREFORE IMPERATIVE. JUST AS THERE ARE MANY CFD TECHNIQUES, THERE ARE ALSO MANY WAYS TO DETERMINE THE ACOUSTIC FIELD GIVEN THEFLOW RESULTS. WE WILL ASSESS THE BEST ACOUSTIC TECHNIQUE FOR EACH OF SEVERAL GENERAL CFD APPROACHES, I.E., THOSE USING FINITE DIFFERENCE, VORTICITY, AND SPECTRAL METHODS. PHASE I WILL FOCUS ON THE CONNECTION BETWEEN CFD AND AEROACOUSTIC THEORY, RECOMMEND MODIFICATIONS AND IMPROVEMENTS IN CFD TECHNIQUES USED FOR NOISE CALCULATIONS, EVALUATE THE COMPUTATIONAL POTENTIAL FOR HYPERSONIC FLOWS, AND RECOMMEND SPECIFIC COMPUTATIONAL TECHNIQUES TO BE STUDIED AND DEVELOPED IN PHASE II.