Multidisciplinary Design Optimization Activities at CASDE, I I T, Bombay

February 7, 2003 MDO MDO - 1

Multidisciplinary Design Optimization

Activities at CASDE, I I T, Bombay

http://www.casde.iitb.ac.in/MDO/activities-at-a-glance.ppthttp://www.casde.iitb.ac.in/MDO/activities-at-a-glance.ppt


Aug 1999 - CASDE initiates MDO activities

Aug 2000 - First meeting of SIG-MDO

Jan 2001 - Professional Development Course on MDO

Jun 2002 - Second meeting of SIG-MDO, Workshop

on MDO

Feb 2003 - Third Meeting of SIG-MDO

Sep 2003 - International Conference on MDO

MDO@CASDE Over the Years


Design / MDO Studies @CASDE

AEW System Level Optimization

Aero-elastic Design of Transport A/C wings

Aircraft Intake (3D-Duct) design Low Fidelity Analysis High Fidelity Analysis (CFD)


Design / MDO Studies @CASDE

MDO Studies in formative stages

Hypersonic Vehicles - Integrated System Optimization (with DRDL)

Launch Vehicles - Reliability Based Design (with VSSC)

Launch Vehicle – Simultaneous optimization of trajectory & system (with VSSC)


Rotodome PlatformRadar Heat exchanger

AEW System

P, H, V, CL

Mission

D2 D3

P H, V

D4

H, V, CL

D1

E

WHX CD,H D, T L, W EWR QrBAntLAnt

WAnt

WRot CD,RWds

User requirements

DC

Design Optimization of AEW


Stage I : Analysis based on empirical formulae

Stage II : semi-empirical analysis realistic aerodynamic loading - VLM simplified structural analysis - EPM

Stage III : Hi-fidelity analysis with aeroelasticity

VLM FEM - NASTRAN

MDO of Transport Aircraft Wing


~150 seater aircraft Mission profile shown B 737-200 candidate for numerical study

1 2

3 4

5

67 8

Takeoff at sea leveld ≤ 2150 m

Climb to 11000 mat best

ROC ≥ 11 m/s

Loiter 45 min(Reserve)

Land at sea leveld ≤ 1220 m

Descend to1500 m

Cruise for 3000 Km at best range M ≥ 0.74

MDO of Transport Aircraft Wing – Baseline Problem


Simultaneous aerodynamic and structural optimization variables - wing aerodynamic shape + wing structural sizing constraints - mission, aerodynamics, structural, aeroelastic

Optimizers : FFSQP / NPSOL (SQP) Aerodynamic analysis : Vortex Lattice Method (VLM) Structural analysis :

Medium fidelity – Equivalent Plate Method (EPM) High fidelity – Finite Element Method (MSC NASTRAN)


Analysis tools

MDO Problem


Aerodynamic Geometry

• Planform• Geometric Pre-twist• Camber• Wing t/c

y

x

• single sweep, tapered wing

• divided into stations

• S, AR, ,

citp

b/2

croot

AR = b2/S

= citp/croot

Wing stations




Structural Geometry

• Cross-section• Box height• Skin thickness• Spar/ribs

yA

A

A

x

A

• symmetric

• front, mid & rear boxes

• r1, r2

l1 l2

c

r1 = l1/c

r2 = l2/c



Function Evaluations

Structural Stresses (x , y , xy ) Structural Weight (Wt) Deformation Function (W(x,y)) / Nodal displacements

Aerodynamic & Mission CL ,sectional Cl , CDi (VLM)

Mdiv (semi-empirical) & CDo (empirical)

Vstall, , Takeoff & Landing Distance Ceiling, ROC, Cruise Mach No.

Geometric Fuel volume (Vf)



Loads

Load case - quasi-static pull-up maneuver Aerodynamic pressure loads Engine loads Inertia Relief

Fuel Weight Inertia Relief Wing Mass Inertia Relief Both are distributed as equivalent uniform pressures over

wing stations



Aerodynamic

Arstsh’2h’

1hrootr2r1d/ch/ciARW/S

StructuralAerodynamic

System Analysis

Structural

VfWtMdddtoRCLCl Cdo



Aerodynamic

Arstsh’2h’



Structural

VfWtMdddtoRCLCl

VLM

FEM

Cdo



Aerodynamic

Arstsh’2h’



Structural

VfWtMdddtoRCLCl

VLM

FEM

Cdo

Fidelity level forMdd and Cdo ?


Optimizer FSQP

I

N

T

E

R

F

A

C

E

History Block

Input Processor

Output Processor

Aerodynamics(VLM)

Structures MSC/

NASTRANNASTRANI

nterface

Analysis Block

AeroelasticityIterator

Optimization Framework ArchitectureMDO of Transport Aircraft of Wing



• For more information

http://www.casde.iitb.ac.in/MDO/

• Contact : [email protected]


3D-Duct Design

Composite team ADA, Bangalore CFD Centre, IIT Bombay CASDE, IIT Bombay

Bring in CFD into Optimization loop Commercial codes? In-house codes?


3-D Duct DesignDesign Problem in Brief

Entry Exit Location and shape known

Geometry of duct from Entry to Exit ?

• Pressure Recovery?• Distortion?• Swirl?


3D-Duct Design Parametrization

Y

X

Z

XDuct Centerline

A

X

Control / Design Variables

• Ym, Zm

• AL/3, A2L/3

Cross Sectional Area


Y

X

Z

XDuct Centerline

A

X

Control / Design Variables

• Ym, Zm

• AL/3, A2L/3

Cross Sectional Area

3D-Duct Design Parametrization


Typical 3D-Ducts Generated


3D-Duct Design Using Low Fidelity Analysis

Low Fidelity Design Criteria (Constraints) Wall angle < 6° Diffusion angle < 3° 6 * Equivalent Radius < ROC of Centerline

Low fidelity analysis for pressure recovery (Objective function)

No low fidelity analysis for distortion or swirl

For results & discussionhttp://www.casde.iitb.ac.in/MDO/3d-duct/


3D-Duct Design Using High Fidelity Analysis

Low Fidelity Design Criteria (Constraints) Wall angle < 6° Diffusion angle < 3° 6 * Equivalent Radius < ROC of Centreline

CFD (Fluent) for pressure recovery & distortion Doyle Knight’s Group @Rutger’s University

Optimization of width-depth of bump for minimising distortion.

Grid quality required to capture distortion?



?

X1-MINX1-MAX

X2-MAX

X2-MIN

Domain for search using high fidelity code is large



Low Fidelity Design Criteria Wall angle < 6° Diffusion angle < 3° 6 * REQ < ROC

Fluent for CFD RSM / DOE DACE

X1-MINX1-MAX

X2-MAX

X2-MIN



Low Fidelity Design Criteria Wall angle < 6° Diffusion angle < 3° 6 * REQ < ROC

Fluent for CFD RSM / DOE DACE

X1-MINX1-MAX

X2-MAX

X2-MIN

http://www.casde.iitb.ac.in/MDO/3d-duct/


MDO Framework

Easy integration of analysis modules Support for distributed analysis Optimization environment . . .

Salas & Townsend AIAA-98-4740 Commercial Frameworks are available


Why do you want my program?

I have a new version of analysis software

You have to know my code to be able to execute it!

(it’s all in Russian)

System Designer’s Nightmare!

I cannot find the correct tuning parameters!

MDO Framework Issues


MDO Framework Issues

Aerodynamics Expert

Structures Expert Controls ExpertSystem Analysis

Analysis codes should reside with experts.

System analysis should execute analysis codes on experts’ computers.


Framework Development @CASDE

Distributed computing (CORBA based)

Database driven Tools to integrate analysis modules

using wrappers Automatic data exchange between

analysis modules


Framework Architecture

Database

ConfigurationManager

ExecutionManager

Sequence Logic

MDOController

NameServer

DataServer

OPT1

Optimizer Manager

OPT2 OPT3

AM1

AnalysisManager

AM2 AM3

GUI


Optimization Issues

• Gradient based optimization

• Evaluation of gradients? Finite Difference. Requirements on convergence more severe than that required for engineering analysis.

• Noisy functions?

X

f


User Supplied Gradients

Complex AnalysisCode in Fortran

Manually extractsequence of mathematical

operations

Code the complex derivative evaluator

in Fortran

Manually differentiatemathematical

functions - chain rule

FORTRANsource code

that can evaluategradients



Manually extractsequence of mathematical

operations

Use symbolic math packages to automate derivative evaluation


in Fortran

Complex AnalysisCode in FORTARN

FORTRANsource code




Parse and extract the sequence

of mathematical operations

Use symbolic math packages to automate derivative evaluation


in Fortran


FORTRANsource code



Gradients by ADIFOR


FORTRANsource code


Automated Differentiation

PackageEuler


Presentation made on behalf of

CASDEPM Mujumdar, K Sudhakar

Amitay Isaacs, SK Sane, AG Marathe

VISIT

http://www.casde.iitb.ac.in/

for information on MDO & Other activities

Multidisciplinary Design Optimization Activities at CASDE, I I T, Bombay

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