Benchmarking ceasiom software to predict flight control and flying qualities of the b 747
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Benchmarking CEASIOM Software to Predict Flight Control and Flying Qualities of the B-747 A. Da Ronch The University of Liverpool, UK C. McFarlane, C. Beaverstock Bristol University, UK J. Oppelstrup, M. Zhang, A. Rizzi Royal Institute of Technology, Sweden. Introduction

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Benchmarking CEASIOM Software to Predict Flight Control and Flying Qualities of the B-747

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Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

Benchmarking CEASIOM Software to Predict Flight Control and Flying Qualities of the B-747

A. Da Ronch

The University of Liverpool, UK

C. McFarlane, C. Beaverstock

Bristol University, UK

J. Oppelstrup, M. Zhang, A. Rizzi

Royal Institute of Technology, Sweden


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

  • Introduction

  • Contemporary aircraft conceptual design

    • Handbook methods, semi-empirical theory

    • Need to recalibrate these empirical methods

    • Augmented-stability & extended flight envelope

      • More accurate flight dynamics modelling

      • Computational methods based on first principle

      • First-Time-Right with the FCS design architecture


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

  • CEASIOM

  • Computerized Environment for Aircraft Synthesis and Integrated Optimization Methods

    • SimSAC project under the European Commission 6th Framework Programme

    • Integrates discipline-specific tools for conceptual design to predict flying & handling qualities

    • http:/www.simsacdesign.eu

    • http:/www.ceasiom.com


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

Objectives


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

CEASIOM main GUI


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

  • Test Case: Boeing 747

  • Large 4-engined turbofan; 350+ pax

  • Multiple control surfaces: Krueger LE flaps, triple-slotted TE flaps

  • Flight dynamics with FCSDT to evaluate different fidelity-level approx


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

  • Adaptive Fidelity CFD

    • DATCOM

      • Semi-empirical

    • TORNADO

      • Vortex-Lattice method

    • EDGE

      • CFD solver

Fidelity

CPU Time

Geometry


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

  • Adaptive Fidelity CFD

    • DATCOM

      • Semi-empirical

    • TORNADO

      • Vortex-Lattice method

    • EDGE

      • CFD solver

  • For conventional aircraft, estimate aero derivatives based on geometry details and flight conditions

  • Suspect results for new configuration

  • Handbook


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

  • Adaptive Fidelity CFD

    • DATCOM

      • Semi-empirical

    • TORNADO

      • Vortex-Lattice method

    • EDGE

      • CFD solver

      • http:/www.redhammer.se/tornado/

  • Modified horse-shoe vortex singularity method

  • Steady & low reduced-freq harmonic unsteady flows

  • Prandtl-Glauert similarity role for compressibility

  • Fuselage can be modelled


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

  • Adaptive Fidelity CFD

    • DATCOM

      • Semi-empirical

    • TORNADO

      • Vortex-Lattice method

    • EDGE

      • CFD solver

  • 3D NS/Euler, compressible flow solver from FOI, Sweden

  • Unstructured grids with arbitrary elements; node-centred FV

  • Explicit Runge-Kutta integration to steady state

  • Semi-implicit, dual-time method for unsteady problem

  • Acceleration techniques, turbulence models, parallel implementation


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

  • CFD Code - EDGE

    • Deflection of control surfaces

      • Generation of a new grid for every new configuration of deflected control surfaces

      • clean geometry

      • tens of grids needed

      • Transpiration BCs

      • only one single grid needed

      • limits on min/max deflection


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

Challenges

How to automate grid generation for CFD?

How to do 100k CFD?

How to do S&C analysis early in design phase?

“...whether CFD can participate in the design process with sufficient speed to drive down the design cycle time”, Dawes et al.


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

Challenges

How to automate grid generation for CFD?

How to do 100k CFD?

How to do S&C analysis early in design phase?


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

From Geometry to CFD Grid (1)

  • AcBuilder: sketch-pad

  • Edit XML file to match new design

  • Visual interpretation


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

  • From Geometry to CFD Grid (2)

  • SUMO* (SUrfaceMOdeler)

  • Rapid generation of 3D water-tight geometry

  • Automated generation of unstructured surface mesh

  • Triangulation based on in-sphere criterion, better than Delaunay, for skewed surfaces

  • Volume mesh using TetGen

    • *http:/www.larosterna.com/dwfs.html


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

From Geometry to CFD Grid (2)

SUMO surface grid


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

From Geometry to CFD Grid (2)

SUMO volume grid


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

From Geometry to CFD Grid


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

TORNADO Geometry


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

TORNADO Geometry

Munk’s theory

Sink/source distribution


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

TORNADO Geometry


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

Challenges

How to automate grid generation for CFD?

How to do 100k CFD?

How to do S&C analysis early in design phase?


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

Aerodynamic Table Format

Non-conventional controls


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

  • Brute Force Approach

  • Simple example; let’s assume:

    • 10 values for AoA, Mach, Beta, Elev, Rud, Ail

    • More than 100k entries needed in table

    • 10 seconds each calculation using TORNADO


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

  • Brute Force Approach

  • Simple example; let’s assume:

    • 10 values for AoA, Mach, Beta, Elev, Rud, Ail

    • More than 100k entries needed in table

    • 10 seconds each calculation using TORNADO

    • 106 / (24 * 60 * 60) > 10 days

    • Brute force approach not feasible to fill-in aero tables!


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

Sampling & Data Fusion

Flight Dynamics

Database

Existing

Table

Increments to

Design

Aerodynamic Tables

Data Fusion for Aerodynamic Increments

Kriging

Sampling

New Design

Journal of Aircraft, 46 (3), 2009


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

  • Sampling & Data Fusion

  • STATIC effects:

    • Sampling for M-α-β dependence

    • Co-Kriging to calculate increments (controls)

  • DYNAMIC effects:

    • No frequency dependence

    • Alpha dependence only

    • Replace unsteady time-accurate with HB method? *

    • Stability derivatives from DATCOM

* AIAA Journal, 47 (4), 2009


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

Challenges

How to automate grid generation for CFD?

How to do 100k CFD?

How to do S&C analysis early in design phase?


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

  • FCSDT

  • FCSDT (Flight Control System Design Toolkit)

    • Design of the FCS, FCS architecture design

    • Reliability analysis, failure mode analysis

    • Control allocation, response simulation

    • S&C analysis, HQ assessment, control laws design, control laws definition, flight simulation


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

  • Aerodynamic Predictions

  • Low speed aerodynamics

  • Transonic regime

    • DATCOM

    • TORNADO

    • TORNADO with compressibility correction

    • EDGE in Euler mode

  • More comparisons in the paper; exp data from Rodney, C.H., Nordwall, D.R., 1970


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

CL vsα, Mach = 0.80


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

CD vs CL, Mach = 0.80


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

Cm vsα, Mach = 0.80


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

Mach = 0.80

AoA = 1.0 deg

Positive elev deflection


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

  • Results

  • Cruise condition

    • Trim & Stability analysis

    • Eigen-structure assignment for feedback controller A + B *K

    • Flight Handling Qualities

  • Failed lower rudder segment

    • Trim & Stability analysis


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

Trimmed AoA


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

Trimmed elevator


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

Pole plot, Mach = 0.8

  • Short Period

  • Dutch-Roll

  • Phugoid


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

  • Results

  • Cruise condition

    • Trim & Stability analysis

    • Eigen-structure assignment for feedback controller A + B *K

    • Flight Handling Qualities

  • Failed lower rudder segment

    • Trim & Stability analysis

  • Eigen value: -2 ± i *2 for Short Period mode


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

Kα: gain value of feedback AoA to elevator

Kq: gain value of feedback pitch rate to elevator


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

  • Results

  • Cruise condition

    • Trim & Stability analysis

    • Eigen-structure assignment for feedback controller A + B *K

    • Flight Handling Qualities

  • Failed lower rudder segment

    • Trim & Stability analysis


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

Short Period mode

  • Eigenvalue: ƞ + i *ωT1/2 = ln(2) / |ƞ|


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

Phugoid mode

  • ξ: damping ratioωn: undamped circular freq


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

Dutch Roll mode

  • ξ: damping ratioωn: undamped circular freq


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

  • Results

  • Cruise condition

    • Trim & Stability analysis

    • Eigen-structure assignment for feedback controller A + B *K

    • Flight Handling Qualities

  • Failed lower rudder segment

    • Trim & Stability analysis

  • Lower rudder segment failed at -10o for range of Mach numbers


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

  • Conclusions

  • Aero tables for flight mechanics

    • Automated generation of CFD grid

    • From low-fidelity methods to CFD

    • Multiple control surfaces

    • Smart procedure to fuse data

  • Test case: Boeing 747, trim analysis & poles plot

    • Cruise condition

    • Failure analysis: lower rudder segment jammed

  • Demonstrated

    • Robust process for S&C analysis in early design

    • CFD needed for good prediction for a realistic test case


Benchmarking ceasiom software to predict flight control and flying qualities of the b 747

  • Future Works

  • Flight manoeuvre replay

    • Aero table with dynamic derivatives from HB

    • Replay with CFD

    • When does prediction fail? * Unsteady effects?

  • Need to review model for flight mechanics

    • System ID

    • Indicial (successfully used in gust analyses)

    • State Space

    • Towards modelling of unsteady effects

* AIAA-2009-6273


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