Aero-Propulsive-Elastic Modeling Using OpenVSP

Transcription

1 Aero-Propulsive-Elastic Modeling Using OpenVSP August 8, 213 Kevin W. Reynolds Intelligent Systems Division, Code TI NASA Ames Research Center

2 Our Introduction To OpenVSP

3 Overview! Motivation and Background! OpenVSP Modeling and Tools! Aerodynamics! Structures! Propulsion! Modeling Aeroelasticity! Flutter Analysis! Flight Dynamic Modeling! Future Work

4 Motivation and Background! Lightweight Materials introduce (1) wing flexibility and (2) significant changes in aircraft weight! Synergistic benefits using lightweight materials (i.e. induced drag reduction)! Spanwise lift distribution control Potential Benefits! Structural weight reduction! Fuel burn reduction! Advanced Propulsion seeks to (1) improve propulsive efficiency and (2) eliminate control surfaces! Synergistic benefits with more electric propulsion systems (i.e. rapid response)! Potential vertical tail weight reduction Potential Benefits! Increase by-pass ratio! Fuel burn reduction! Opportunity: Exploit multidisciplinary interactions while maintaining aero-structural stability! Mission adaptive wing shaping! Improved off-design performance! Potential reduction in system and aircraft weight! Exploitation of aeroelastic instabilities Can a synergistic benefit of fuel burn reduction be achieved over a mission profile?

5 Design Tool For Analyzing Advanced Aircraft Concepts High Aspect Ratio Wings Hybrid Electric Distributed Propulsion Electric Aircraft Unmanned Aerial Vehicles Flexible materials and advanced propulsion will be an integral part of future aircraft concepts.

6 Multidisciplinary Optimization Tools Optimizer Objective Design Variables X wing = {a 4,a 3,a 2,b 4,b 3,b 2 }, Geometry Y prop = {d,u,d 1,u 1,d 2,u 2,...,d n,u n,} Z traj = {h 1,v 1,h 2,v 2,...,h n,v n,} Atmosphere Aerodynamics Lift Distribution, Performance Propulsion Vorlax/CBAero Structures NPSS/WATE Stability Finite Element Model Weight Estimation Control Performance Estimation

7 Overview! Motivation and Background! OpenVSP Modeling and Tools! Aerodynamics! Structures! Propulsion! Modeling Aeroelasticity! Flutter Analysis! Flight Dynamic Modeling! Future Work

8 Aerodynamic Analysis Using OpenVSP and Vorlax 2 3 Run Vorlax Export.out file Pressure Distribution 1 Install Vorlax Planform Geometry Lift Curves Drag Polars Vertical Lift Distribution The Vorlax engine can rapidly generate lift curves and drag polars across various Mach numbers.

9 Propulsion Layout and Design Effects Wing Aerodynamics Clean Wing Concept 1 Baseline GTM Concept 2 Higher fidelity tools can be used to redesign the propulsion layout and geometry for minimizing aerodynamic penalties.

10 2 Mass Properties and Moments of Inertia 1 Baseline Aircraft Define mass properties Calculate moments of inertia Wing Weight Distribution Moments of Inertia Mass [slug-ft 2 ] Weight [lb-ft 2 ] Roll, I xx 1,77, 56,947,97 Pitch, I yy 5,68, 182,748,287 Yaw, I zz 7,27, 233,94,937 Spanwise weight distributions can either be specified or estimated using structural analysis techniques.

11 Structural Modeling of the Wing Upgraded Finite-Element Model and Geometry Generation Tools Integrated aeroelastic model for flapwise and chordwise deformation capability

12 Propulsion System Modeling An analytical model for fan performance was developed as a complement to the NPSS/WATE tools.

13 Hybrid Electric Propulsion Modeling More Electric Aircraft Design (787 Example) Legend - Battery - Turbo generator - Generator - Transformer - Fan - Fan Motor - Motor Controller - Wire OpenVSP Modeling of a Hybrid Electric Distributed Propulsion Concept

14 Overview! Motivation and Background! OpenVSP Modeling and Tools! Aerodynamics! Structures! Propulsion! Modeling Aeroelasticity! Flutter Analysis! Flight Dynamic Modeling! Future Work

15 Modeling Aeroelasticity Objective: Conduct static and dynamic aeroelastic analysis to model aircraft wing flexibility. Aeroelasticity represents the coupled relationship between unsteady aerodynamics and structural properties.

16 Static Aeroelasticity Solutions Θ (deg), twist positive nose-down W (ft), vertical bending deflection positive up V (ft), chordwise bending deflection positive aft (left wing) V x (deg), bending slope Structural Deflection assuming no coupling W x (deg), bending slope BBL (ft) BBL (ft) BBL (ft) BBL (ft) BBL (ft) Θ (deg), twist positive nose-down W (ft), vertical bending deflection positive up V x (deg), bending slope W x (deg), bending slope V (ft), chordwise bending deflection positive aft (left wing) BBL (ft) BBL (ft) BBL (ft) 6 x BBL (ft).1 Aeroelastic deflection assuming no coupling BBL (ft) Static aeroelasticity represents the response of an undeformed wing to inertial and aerodynamic loads.

17 Flutter Analysis and Unstable 3, feet Cantilever Modes Symmetric Modes Antisymmetric Modes Flutter boundary: Mach = Flutter boundary: Mach = Flutter boundary: Mach = Frequency Response Frequency Response Frequency Response A Mach sweep is required in order to analyze flutter boundaries and the associated frequencies.

18 Dynamic Aeroelastic Solutions Flutter boundaries: Flutter frequencies, rad/s: A Mach sweep is required in order to analyze flutter boundaries and the associated frequencies.

19 Overview! Motivation and Background! OpenVSP Modeling and Tools! Aerodynamics! Structures! Propulsion! Modeling Aeroelasticity! Flutter Analysis! Flight Dynamic Modeling! Future Work

20 Tool Integration for Aero-propulsive-elastic Modeling Coupled Geometry Generation, Structural FEM, and Aerodynamic Modeling! To model flight performance over a mission profile! To capture important multidisciplinary interactions Individual Engine Sizings and SL Thrusts: T SL,i W e,i x e,i y e,i z e,i Thrust-Altitude- Mach Model Propulsion System Model Individual Engine Thrusts: T i Geometry Generation Tool Structural FEM coupled with Vortex Lattice Aero Model Vortex Lattice Aero Model Total Sea Level Thrust : T SL Thrust-Altitude- Mach Model Total Thrust Value: T Flexible Wing Trim Tool (for multiple engines) Structural Finite Element Model

21 Aero-Servo-Propulsive-Elastic Flight Dynamic Modeling

22 Future Work We envision OpenVSP being used as a geometry modeling platform for conceptual design, detailed design, and performance modeling within the context of a mission. Couple Geometry Generation, Structural FEM, and Aerodynamic Modeling! To capture important multidisciplinary interactions! To model performance benefits over a mission profile! Fuel burn reduction! Low speed performance Model Complex Interactions Between Lightweight Structures and Advanced Propulsion! To account for wing flexibility and structural deformation! To investigate flutter conditions and unstable modes! To analyze propulsion response and performance Quantify Mission Performance Benefits Based on Design and Analysis! To analyze on-design mission performance! To analyze off-design mission performance! To build pilot intuition for flying future aircraft concepts

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