ADVANCED DYNAMICS

ADVANCED DYNAMICS, INC - SBIR PH II

RESEARCH IS PROPOSED FOR THE DEVELOPMENT OF A STATE-OF-THE-ART COMPUTATIONAL AEROELASTIC TOOL. THIS TOOL WILL INCLUDE VARIOUS LEVELS OF FIDELITY AND THE ABILITY TO PERFORM COMPUTATIONAL UNCERTAINTY QUANTIFICATION FOR DATA-DRIVEN RISK ANALYSIS AND CERTIFICATION. A NUMBER OF NOVEL REDUCED-ORDER IN TIME METHODS WILL BE IMPLEMENTED INTO THE CODE ALLOWING FOR EFFICIENT AND ACCURATE AEROELASTIC SIMULATION WHICH WILL ENABLE BOTH THE EXPLORATION OF COMPLEX PHYSICS, POINT DESIGN AND FAST GENERATION OF "TRAINING DATA" FOR REDUCED ORDER SPATIAL AEROELASTIC MODELS. THE VARIOUS LEVELS OF FIDELITY AVAILABLE IN THE CODE FOR AEROELASTIC MODELING WILL RANGE FROM CFD-BASED (BOTH GRID-BASED AND A NOVEL PARTICLE-BASED METHOD) SIMULATION TO REDUCED-ORDER AEROELASTIC MODELS BASED UPON VOLTERRA SERIES REPRESENTATIONS AND PROPER ORTHOGONAL DECOMPOSITION (POD). THE APPLICATION OF THE PROPOSED INNOVATIONS SPANS THE RANGE OF FLIGHT, FROM HIGH-SPEED TRANSPORT VEHICLES, TO SMALL-SCALE, FLAPPING MICRO-AIR VEHICLES. ANTICIPATED RESULTS INCLUDE 1) THE FURTHER VALIDATION AND IMPLEMENTATION OF THE PROPOSED NOVEL TIME-REDUCED ORDER MODELS INTO THE EXISTING ASTE-P SOLVER FRAMEWORK (WHICH ALREADY INCLUDES THE VARIOUS LEVEL FIDELITY MENTIONED ABOVE), 2) APPLICATION OF THE PROPOSED WORK TO LARGE-SCALE SIMULATION AND COMPARISON WITH EXPERIMENT, AND 3) ADVANCEMENT OF THE STATE OF KNOWLEDGE FOR NONLINEAR PROBLEMS IN AEROELASTICITY IN BOTH THE SUBSONIC, LOW REYNOLDS NUMBER REGIME AND TRANSONIC HIGH REYNOLDS NUMBER REGIME.

INTEGRATED VARIABLE-FIDELITY TOOL SET FOR MODELING AND SIMULATION OF AEROSERVOTHERMOELESTICITY- PROPULSION (ASTE-P) EFFECTS FOR AEROSPACE VEHICLES RANGING FROM SUBSONIC TO HYPERSONIC FLIGHT

FINAL REPORT AND PROJECT SUMMARY - SBIR PHASE I

(STTR PHASE 1) NOVEL, OPTIMAL, PHYSICS-BASED REDUCED ORDER MODELS FOR NONLINEAR AEROELASTICITY

AEROELASTIC MODEL UPDATING

STTR PHASE I - AN INNOVATIVE SOFTWARE TOOL FOR BLADES STRESS ESTIMATION DURING MULTIPLE SIMULTANEOUS VIBRATORY MODE

RESEARCH IS PROPOSED FOR THE DEVELOPMENT AND IMPLEMENTATION OF STATE OF THE ART, REDUCED ORDER MODELS FOR PROBLEMS IN NONLINEAR AEROELASTICITY. HIGHLY EFFICIENT AND ACCURATE AEROELASTIC SIMULATION TOOLS WILL BE CONSTRUCTED BASED UPON THE MATHEMATICAL FORMALISM OF OPTIMAL PREDICTION THEORY AND A NOVEL IMPLEMENTATION OF A FILTERED HARMONIC BALANCE SOLUTION METHODOLOGY. THE IMPLICATIONS OF THE PROPOSED WORK INCLUDE ORDERS OF MAGNITUDE REDUCTION IN COMPUTATIONAL TIME, WITH MINIMAL LOSS OF ACCURACY, FOR TIME PERIODIC PROBLEMS IN NONLINEAR AEROELASTICITY. THE APPLICATION OF THE PROPOSED INNOVATIONS SPANS THE RANGE OF FLIGHT, FROM HIGH-SPEED TRANSPORT VEHICLES, TO SMALL-SCALE, FLAPPING MICRO-AIR VEHICLES. ANTICIPATED RESULTS INCLUDE 1) THE IMPLEMENTATION OF THE PROPOSED REDUCED ORDER METHODOLOGY INTO BOTH A STANDARD GRID-BASED AEROELASTIC TOOL AND A MATERIAL POINT METHOD MONOLITHIC AEROELASTIC SOLVER FOR THE PRODUCTION OF TECHNOLOGY READY, MULTI-FLOW REGIME AEROELASTIC SIMULATION TOOLS 2) APPLICATION OF THE PROPOSED WORK TO LARGE-SCALE SIMULATION AND COMPARISON WITH EXPERIMENT AND "FULL-ORDER" AEROELASTIC SIMULATIONS AND 3) ADVANCEMENT OF THE STATE OF KNOWLEDGE FOR NONLINEAR PROBLEMS IN AEROELASTICITY IN BOTH THE SUBSONIC, LOW REYNOLDS NUMBER REGIME AND TRANSONIC HIGH REYNOLDS NUMBER REGIME.

PHYSICS-BASED IDENTIFICATION, MODELING AND RISK MANAGEMENT FOR AEROELASTIC FLUTTER AND LIMIT-CYCLE OSCILLATIONS (LCO) THE PROPOSED RESEARCH PROGRAM WILL DEVELOP A PHYSICS-BASED IDENTIFICATION, MODELING AND RISK MANAGEMENT INFRASTRUCTURE FOR AEROELASTIC TRANSONIC FLUTTER AND LIMIT-CYCLE OSCILLATIONS (LCO). THIS CAPABILITY WILL BE BUILT UPON HIGH FIDELITY STATE-OF-THE-ART THEORETICAL/COMPUTATIONAL METHODS AS VALIDATED AND VERIFIED BY AVAILABLE EXPERIMENTAL DATA BASES, AND WILL INCLUDE (1) RAPID FLUTTER BOUNDARY DETERMINATION FOR A WIDE RANGE OF CONFIGURATIONS; (2) AN ASSESSMENT OF THE RELATIVE IMPORTANCE OF VARIOUS AERODYNAMIC AND STRUCTURAL NONLINEARITIES FOR AIRCRAFT AND AEROSPACE CONFIGURATIONS THAT ARE DETERMINED TO BE FLUTTER CRITICAL AND HENCE POTENTIALLY CAPABLE OF LCO; (3) AN ASSESSMENT OF EXPECTED LCO AMPLITUDES BASED UPON HIGH FIDELITY COMPUTATIONAL MODELS; (4) AN ASSESSMENT OF THE POTENTIAL FOR ACTIVE AND/OR PASSIVE ALLEVIATION OF LCO; AND (5) A PROPOSED RISK MANAGEMENT METHODOLOGY THAT INCORPORATES A PREDICTION OF TOLERABLE LCO AMPLITUDES AND THE CAPABILITY FOR REDUCING UNACCEPTABLE LCO RESPONSE. KEY CHALLENGES AND MILESTONES TO BY MET INCLUDE (1) A DEMONSTRATION OF THE USE OF NAVIER-STOKES BASED CFD MODELS AND NONLINEAR STRUCTURAL MODELS, INCLUDING THE USE OF SYSTEM IDENTIFICATION METHODS AS APPROPRIATE AND NEEDED TO PREDICT FLUTTER AND LCO; (2) A DEMONSTRATION OF ACCURATE MODELING OF AERODYNAMIC AND STRUCTURAL NONLINEARITIES SUCH AS LARGE SHOCK WAVE MOTION, SEPARATED FLOW, STRUCTURAL FREEPLAY AND LARGE GEOMETRIC STRUCTURAL DEFLECTIONS AND THEIR IMPACT ON FLUTTER AND LCO; (3) CHARACTERIZATION AND EVALUATION OF NONLINEAR DAMPERS AND NONLINEAR STIFFNESS DEVICES FOR ALLEVIATING LCO; (4) CHARACTERIZATION AND EVALUATION OF ACTIVE CONTROL SYSTEMS FOR ALLEVIATING LCO; AND (5) DESIGN AND DEMONSTRATION IN WIND TUNNEL TEST AND FLIGHT TEST OF AN LCO ALLEVIATION DEVICE.

TOWARDS EFFICIENT VISCOUS MODELING BASED ON CARTESIAN METHODS FOR AUTOMATED FLOW SIMULATION THE PROPOSED WORK AIMS AT DEVELOPING TECHNIQUES THAT WILL ADDRESS THE CURRENT LIMITATIONS OF CARTESIAN-BASED NAVIER-STOKES CFD SCHEMES BY EXPLORING THREE PROMISING METHODS OF IMPLEMENTING IMPROVED WALL BOUNDARY CONDITIONS. THE THREE METHODS ARE BASED ON: (1) THE DIAMOND STENCIL APPROACH OF DELANAYE ET AL., (2) THE EXTRAPOLATION BOUNDARY CONDITION WORK BY MARSHALL AND RUFFIN, AND (3) THE MATERIAL POINT METHOD DEVELOPED BY ADVANCED DYNAMICS. THE KNOWLEDGE GAINED FROM PROTOTYPE IMPLEMENTATIONS OF THESE SCHEMES WILL LEAD TO THE DEVELOPMENT OF AN EFFICIENT VISCOUS MODELING ALGORITHM SUITABLE TO GENERAL CARTESIAN CFD CODES AT THE END OF PHASE I. PHASE II WILL INTEGRATE THIS ALGORITHM INTO A LARGE-SCALE CARTESIAN CFD CODE IN CONSULTATION WITH NASA TECHNICAL REPRESENTATIVE. PHASE III WILL COMMERCIALIZE THE RESULTING TECHNIQUES TO BE DEVELOPED IN PHASES I AND II AND DEMONSTRATE THEIR APPLICABILITY TO A WIDE RANGE OF PROBLEMS.

THE NEED TO ACCURATELY PREDICT AEROELASTIC PHENOMENON FOR A WIDE RANGE OF MACH NUMBERS IS A CRITICAL STEP IN THE DESIGN PROCESS OF ANY AEROSPACE VEHICLE. COMPLEX AERODYNAMIC PHENOMENON SUCH AS VORTEX SHEDDING, SHOCK-TURBULENCE INTERACTION, SEPARATION, ETC. DOMINATE AT TRANSONIC AND SUPERSONIC MACH NUMBERS AND HENCE THE NEED TO ADDRESS THESE PHENOMENA IS OF UTMOST IMPORTANCE IN THE MODELING PROCESS. RESEARCH IS PROPOSED FOR THE DEVELOPMENT AND IMPLEMENTATION OF STATE OF THE ART, LARGE-EDDY-SIMULATION (LES) BASED COMPUTATIONAL MODELS FOR PROBLEMS IN NONLINEAR AEROELASTICITY. HIGHLY EFFICIENT AND ACCURATE SUBGRID-SCALE (SGS) MODELS WILL BE INCORPORATED INTO THE FLOW SOLVER AND COUPLED WITH HIGH FIDELITY STRUCTURE SOLVERS TO PREDICT AEROELASTIC PHENOMENA SUCH AS TRANSONIC FLUTTER, LIMIT CYCLE OSCILLATIONS, ETC. THE SGS MODELS PROPOSED ARE BASED ON EDDY-VISCOSITY AND NON-EDDY-VISCOSITY MODELS AND THEY WILL BOTH BE ASSESSED FOR ACCURACY AND ROBUSTNESS IN THE CONTEXT OF NONLINEAR AEROELASTICITY. THE IMPLICATIONS OF THE PROPOSED WORK INCLUDE USING HIGHLY ACCURATE TURBULENCE MODELS WITH EFFICIENT FINITE ELEMENT MODELS OF STRUCTURE TO SOLVE PROBLEMS IN NONLINEAR AEROELASTICITY. THE APPLICATION OF THE PROPOSED INNOVATIONS SPANS THE RANGE OF FLIGHT, FROM SUBSONIC TO SUPERSONIC TRANSPORT VEHICLES. ANTICIPATED RESULTS INCLUDE 1) THE IMPLEMENTATION OF THE PROPOSED LES METHODOLOGY INTO CURRENT AEROELASTIC TOOLSET 2) APPLICATION OF THE PROPOSED WORK TO LARGE-SCALE SIMULATION AND COMPARISON WITH EXPERIMENT AND LOWER FIDELITY RANS-BASED AEROELASTIC SIMULATIONS AND 3) ADVANCEMENT OF THE STATE OF KNOWLEDGE FOR NONLINEAR PROBLEMS IN AEROELASTICITY.

THE PROPOSED WORK WILL ESTABLISH HIGH FIDELITY COMPUTATIONAL METHODS AND WIND TUNNEL TEST MODEL IN SUPPORT OF NEW FREEPLAY CRITERIA FOR THE DESIGN, CONSTRUCTION AND CONTROLLED ACTUATION OF CONTROL SURFACES WITH VARYING AMOUNTS OF FREEPLAY AND THEIR AEROELASTIC RESPONSE. THESE METHODS WILL BE VALIDATED WITH WIND TUNNEL AND FLIGHT TEST DATA. IN PHASE I A NONLINEAR COMPUTATIONAL AEROSERVOELASTIC METHODOLOGY WILL BE DEVELOPED FOR FREEPLAY INDUCED FLUTTER/LCO AND GUST RESPONSE. VALIDATION WILL BE ACHIEVED BY COMPARISONS WITH LEGACY AND NEW WIND TUNNEL TEST DATA. IN PHASE II THE METHODOLOGY WILL BE GENERALIZED TO CREATE A MATURE SOFTWARE CAPABILITY FOR CLOSED-LOOP AEROELASTIC SYSTEMS IN THE TRIMMED/UNTRIMMED STATE INCLUDING GUST, STICK OR RANDOM AEROACOUSTIC EXCITATIONS. AN ALL MOVABLE TAIL WING WIND TUNNEL TEST ARTICLE WILL BE DESIGNED AND BUILT WITH VARIABLE FREEPLAY WITH INITIAL TEST EVALUATION COMPLETED IN PHASE I AND A THOROUGH PARAMETER VARIATION DATA SET AND WILL BE DEVELOPED IN PHASE II FOR COMPUTATIONAL CODE VALIDATION IN PHASE II. SUBJECT TO AVAILABLE FUNDING CONSTRAINTS BOTH HIGH SPEED TRANSONIC AS WELL AS SUBSONIC WILL TUNNEL TESTS WILL BE UNDERTAKEN. IN PHASE III THE COMPUTATIONAL METHODOLOGY IN COMBINATION WIND TUNNEL TEST RESULTS WILL BE USED TO SUPPORT THE IMPROVEMENT OF THE CURRENT FAA AND/OR MIL-SPEC FREEPLAY AEROELASTIC RESPONSE CRITERIA. FOLLOWING THE SUCCESSFUL DEMONSTRATION AND VALIDATION OF THE NEW COMPUTATIONAL METHODS, THE METHODOLOGY WILL BE PROPOSED FOR ADOPTION BY FAA FOR COMMERCIAL APPLICATIONS AND THE DOD FOR MILITARY APPLICATIONS WITH THE EXPECTATION THAT ALL MAJOR CIVILIAN AND MILITARY AEROSPACE INDUSTRIES WILL ADOPT THE DESIGN/ANALYSIS METHODOLOGY FOR FREEPLAY INDUCED LCO/FLUTTER PREVENTION.

R&D STTR TOPIC N10A-T003

R&D STTR TOPIC N10A-T010

RESEARCH AND DEVELOPMENT IN THE PHYSICAL, ENGINEERING, AND LIFE SCIENCES (EXCEPT BIOTECHNOLOGY)

RESEARCH AND DEVELOPMENT IN THE PHYSICAL, ENGINEERING, AND LIFE SCIENCES (EXCEPT BIOTECHNOLOGY)

MATLAB/SIMULINK SOFTWARE MODULE WITH MULTI-FIDELITY REDUCED ORDER MODELS FOR FLUTTER/LCO PREDICTION AND SUPPRESSION