CFD-BASED AEROSERVOELASTIC METHODOLOGY FOR SUPERSONIC AIRCRAFT FLUTTER SUPPRESSION GUST LOADS ALLEVIATION,&…

Public award description

CFD-BASED AEROSERVOELASTIC METHODOLOGY FOR SUPERSONIC AIRCRAFT FLUTTER SUPPRESSION GUST LOADS ALLEVIATION,& RIDE QUALITY AUGMENTATION (NRA PROPOSAL #06-SUP2-06-0015) **** THIS SOW DEFINES THE REQUIREMENTS FOR DEVELOPING AND DEMONSTRATING A METHODOLOGY FOR AEROSERVOELASTIC (ASE) CONTROL LAW DESIGN, BASED ON THE PROPOSED HIGH-LEVEL CFD TOOL CARTEULER. THIS METHODOLOGY SHALL BE APPLIED TO THE SUPERSONIC SEMI-SPAN TRANSPORT (S4T) WIND-TUNNEL MODEL TO SIMULTANEOUSLY SUPPRESS FLUTTER (FS), ALLEVIATE GUST LOADS (GLA) AND CONTROL RIDE QUALITY (RQC) AT TRANSONIC/LOW SUPERSONIC CONDITIONS DURING THE CONDUCT OF ASE WIND-TUNNEL TESTS IN THE LANGLEY TRANSONIC DYNAMICS TUNNEL (TDT). TO DESIGN SUCH ASE CONTROL LAWS, THE CONTRACTOR SHALL FOLLOW A BUILDING-BLOCK APPROACH AS FOLLOWS: (A) GENERATE A FAMILY OF LINEARIZED PLANTS (AT VARIOUS MACH NUMBERS AND DYNAMIC PRESSURES TO COVER THE ENTIRE EXPECTED RANGE OF TEST CONDITIONS) BY EXTRACTING THE LINEARIZED UNSTEADY AERODYNAMICS FROM CARTEULER; (B) FOR VARIOUS MACH NUMBERS AND DYNAMIC PRESSURES, DESIGN CLASSIC LINEAR CONTROLLERS BASED ON THE LINEARIZED PLANT. THE INTENT OF THESE CONTROLLERS IS TO ACHIEVE A 20% INCREASE IN FLUTTER SPEED, A 20% REDUCTION IN GUST LOADS, AND A 20% INCREASE IN A MEASURE OF RIDE QUALITY. (C) BASED ON THE KNOWLEDGE GAINED DURING THE DESIGN OF THE CLASSIC LINEAR CONTROLLERS, FOR VARIOUS MACH NUMBERS AND DYNAMIC PRESSURES, DESIGN ROBUST CONTROLLERS USING THE H AND U-DESIGN TECHNIQUES WITH THE GOAL OF ACHIEVING 20% INCREASE IN FLUTTER SPEED, 20% REDUCTION IN GUST LOADS, AND A 20% INCREASE IN A MEASURE OF RIDE QUALITY; (D) BASED ON THE KNOWLEDGE GAINED DURING THE DESIGN OF THE ROBUST CONTROLLERS, FOR VARIOUS MACH NUMBERS AND DYNAMIC PRESSURES, DESIGN LINEAR PARAMETER-VARYING CONTROLLERS WITH THE GOAL OF ACHIEVING 20% INCREASE IN FLUTTER SPEED, 20% REDUCTION IN GUST LOADS, AND A 20% INCREASE IN A MEASURE OF RIDE QUALITY; (E) IN A SIMULINK ENVIRONMENT EMPLOYING CARTEULER AERODYNAMICS, FOR VARIOUS MACH NUMBERS AND DYNAMIC PRESSURES, CONDUCT DIRECT NUMERICAL SIMULATIONS OF EACH OF THE CONTROL LAWS (CLASSIC LINEAR, ROBUST, LINEAR PARAMETER-VARYING) TO ASSESS THEIR STABILITY AND PERFORMANCE. 3.0 TECHNICAL REQUIREMENTS THE CONTRACTOR SHALL ATTEMPT TO MEET THE FOLLOWING TARGET CONTROL-LAW PERFORMANCE METRICS: A SET OF CONTROL LAWS OF VARYING COMPLEXITY SHALL BE DESIGNED OVER A MACH NUMBER RANGE FROM 0.6 TO 1.2 TO SIMULTANEOUSLY: ALLEVIATE GUST LOADS BY A TARGET OF 20%; IMPROVE RIDE QUALITY BY REDUCING A REPRESENTATIVE WING AEROELASTIC AMPLITUDE BY A TARGET OF 20%; AND SUPPRESS FLUTTER BY INCREASING FLUTTER SPEED BY A TARGET OF 20%. FINAL CONTROL-LAW PERFORMANCE METRICS SHALL BE ASSESSED AND REFINED BY NASA AND THE CONTRACTOR NO LATER THAN THE CONTROL LAW PRELIMINARY DESIGN REVIEW. THE CONTRACTOR SHALL ATTEMPT TO MEET THE FOLLOWING TARGET CONTROL-LAW ROBUSTNESS METRICS: THE GUST LOAD ALLEVIATION, RIDE QUALITY CONTROL, AND FLUTTER SUPPRESSION CONTROL LAWS OPERATING ONE AT A TIME AND IN ALL COMBINATIONS SHALL HAVE ADEQUATE GAIN AND PHASE MARGINS OR OTHER SUITABLE MEASURES OF ROBUSTNESS. FINAL CONTROL-LAW ROBUSTNESS METRICS SHALL BE ASSESSED AND REFINED BY NASA AND THE CONTRACTOR NO LATER THAN THE CONTROL LAW PRELIMINARY DESIGN REVIEW.