CALCULATION OF SURFACE PRESSURE FLUCTUATIONS BASED ON TIME- AVERAGED, TURBULENT FLOW COMPUTATIONS

THE STRUCTURAL DYNAMIC ANALYSIS OF A SPACE VEHICLE DURING ATMOSPHERIC FLIGHT REQUIRES KNOWLEDGE OF THE MEAN FLUCTUATING PRESSURE DISTRIBUTION OVER THE SURFACE OF THE VEHICLE. COMPUTATIONAL FLUID DYNAMIC TECHNIQUES CAN READILYCALCULATE THE MEAN PRESSURE COMPONENT BUT NOT THE FLUCTUATING COMPONENT. EXPERIENCE WITH THE TURBULENCE ANALYSIS (TURBAN) SOFTWARE MODEL WILL BE APPLIED TO DEVELOP AN ACCURATE AND EFFICIENT METHOD TO PREDICT THE INTENSITY OFSURFACE-PRESSURE FLUCTUATIONS BASED ON THE PROPERTIES OF THEMEAN FLOW FIELD AS COMPUTED BY STANDARD CFD PROCEDURES. SPECIFIC OBJECTIVES FOR PHASE I ARE: TO ESTABLISH THE BASICGOVERNING EQUATION FOR THE COVARIANCE OF PRESSURE FLUCTUATIONS; TO DETERMINE THE MOST PRACTICAL MUMERICAL PROCEDURE; TO DEVELOP COMPUTATIONAL ALGORITHMS; TO SELECT CANDIDATE TWO-DIMENSIONAL INCOMPRESSIBLE FLOW PROBLEMS WHICHHAVE CFD SOLUTIONS; AND TO PREDICT DISTRIBUTION OF SURFACE PRESSURE FLUCTUATIONS. DURING PHASE II, THE TECHNIQUE WOULD BE EXPANDED TO APPLY, FIRST, TO THREE-DIMENSIONAL INCOMPRESSIBLE FLOW AND, THEN, TO TWO-DIMENSIONAL AND THREE-DIMENSIONAL COMPRESSIBLE FLOW. IN ITS FINAL STAGE OF DEVELOPMENT, THE CONCEPT WOULD TAKE THE FORM OF A CFD POST- PROCESSOR WHICH COULD BE USED IN CONJUNCTION WITH A VARIETY OF CFD SOFTWARE PROGRAMS. COMMERCIAL APPLICATIONS WOULD BE THROUGH THE SALE OF THE SOFTWARE AS A POST PROCESSOR TO COMPANIES DEVELOPING AND UTILIZING CFD SOFTWARE.