COMPUTER SIMULATION AND DESIGN OF JET NOISE SUPPRESSORS

COMPUTATIONAL, RATHER THAN EXPERIMENTAL, METHODS ARE PROPOSED TO DEVELOP, DESIGN, AND TEST THE NOISE SUPPRESSORS THAT WILL BE NEEDED TO QUIET THE JET TURBULENCE NOISE PRODUCED BY THE HIGH SPEED CIVIL TRANSPORT AND OTHER SUPERSONIC VEHICLES. THE VIABILITY OF THIS APPROACH IS DUE TO RECENT ADVANCES IN TURBULENCE THEORY AND NUMERICAL METHODS THAT COMBINE RENORMALIZATION GROUP METHODS AND SPECTRAL ELEMENT TECHNIQUES SO THAT FULLY THREE-DIMENSIONAL, TIME-DEPENDENT FLOWS CAN BE TREATED AT HIGH REYNOLDS NUMBER. THE PHASE I PROGRAM WILL FOCUS ON MORE USER-FRIENDLY PROCEDURES FOR SPECIFYING THE COORDINATES OF THE SUPPRESSOR NOZZLES AND THE COMPUTATIONAL GRID. THE TURBULENT JET FLOWS OF SEVERAL COMPLEX, THREE-DIMENSIONAL NOZZLES WILL BE COMPUTED USING TIME-AVERAGED TURBULENT TRANSPORT METHODS. FULLY TIME-DEPENDENT COMPUTATIONS OF TURBULENCE, AND THE NEAR FIELD SOUND IT PRODUCES, WILL BE PERFORMED FOR PLANAR NOZZLES BOTH WITH AND WITHOUT UPSTREAM EXCITATION. THIS APPROACH WILL LEAD TO MORE RATIONAL AND SYSTEMATIC METHODS FOR THE OPTIMIZATION OF JET NOISE SUPPRESSORS AND ALLOW SIMULATION AT CONDITIONS INACCESSIBLE TO LABORATORY TEST FACILITIES.