Systems Design - New Paradigm K Sudhakar Centre for Aerospace Systems Design & Engineering http://www.casde.iitb.ac.in/ January 28, 2004
Dec 25, 2015
Systems Design - New Paradigm
K SudhakarCentre for Aerospace Systems Design &
Engineering
http://www.casde.iitb.ac.in/January 28, 2004
Systems Engineering
Discipline-1 Discipline-2 Discipline-3
System
Systems Engineering?
Need to view things from one level
higher than your work requires
Designers Design Process
Meta DesignMeta Design
Meta-Design
• Increase breadth of knowledge used in decisions
• Increase depth of knowledge used in decisions
• Shorten design cycle time
• Ability to systematically explore design space
• - -
RequirementsCapture
Design theDesign Process
SpecifyDesign Process
Researcher’s Perception
• Multi-disciplinary : Increased breadth
• Design – process of translating requirements into product specifications.
• Optimization – Formal method of locating the ‘best’ under ‘constraints’
• Implies use of high fidelity tools. Increase depth.
Industry Perception
• Not a turnkey solution to design!
• Only a tool in the hands of designer to – State design problems formally
– Integrate appropriate fidelity analysis
– Explore design space
– Improve design starting from a baseline
If we can find an optima we will be happy!
If we find global optima we will celebrate!
Optimization
Systems Design
Parameters
Requirements asConstraints
Objective
Analysis
Aerodynamics
Structures
Controls
-ilities
Trajectory
An Example – HSCT (1991-’99)!
• HSCT-2– 5 design variables, 6 constraints – WINGDES, ELAPS, Range equation, engine deck – Time for one cycle = 10 minutes
• HSCT-3– 7 design variables, 6 constraints– ISAAC, COMET, Range equation. Engine deck– Time for one cycle = 3 hours
• HSCT-4– 271 design variables, 31,868 constraints– CFL3D, USSAERO, GENESIS, FLOPS, ENG10 – Time for one cycle = 3 days
HSCT - 4
• Detailed problem definition took more than 1 year to extract from people
• Requirements document touched 100 pages merely to define analysis process, tools used and data flow
• 90% of work went into preparing analysis codes for MDA and integrating them in a proper sequence
Where are we?
• Strengths exist in disciplinary analysis
• No focus on Analysis for Design
• No focus on verification / validation to
characterize uncertainties
• No attempt to capture knowledge with
traceability
CASDE @ Workshop on Framework for System Analysis, ISSA, New Delhi, October 13, 2003
Need for groups to
• Define design problem• Define needs for Analysis for Design• Extract / Establish traceability • Perform Verification / Validation to
characterize uncertainty• Explore design methodologies
New Paradigms• MDO – the process• Frame Works – to deploy the process• Multi-criteria decision making• Design under uncertainty
Components• Surrogate Modeling (DOE, RSM, DACE)• Sensitivity Analysis
Design Under Uncertainty
AnalysisXnom Ynom
Ynom Y
p
• V&V, levels of fidelity• How to fuse• Characterisation
XnomX
p
• Characterisation• How to propagate
• How to assemble System Analysis• How to state design problem?
Frame Work
• Essential infrastructure• Disciplinary autonomy, but system level
integration. (Distributed, heterogeneous environment)
• Tools availability• Requirement Capture for Frame Work?• Commercial Frame Works – iSIGHT,
Phoenix Integration, . . .• CASDE MDO FrameWork Version-II
(March 2004)
MDO Framework
Database
ConfigurationServer
ExecutionManager
MDOController
NameServer
DataServer
OPT1
Optimizer Manager
OPT2 OPT3
AM1
AnalysisManager
AM2 AM3
GUI
Control
Data
A1
A2
A3A4
A5
Execution sequence
A13
Execution Unit
A12 A13 A14
Execution sequence of execution units
A22A1
A2
A3
A4
A5
Parallel Execution
• Architectural design - Intuitive GUI, OO principles, standards based
• Problem formulation - Iterative & branching formulations, legacy codes, multiple optimizers
• Problem execution - Automatic execution, parallel & distributed
• Information access – DB management visualization, monitoring
3D-Duct : An Example
• Duct design in the past?• Is improvements in breadth, depth
possible?• Statement of design problem?• Analysis Tools - Identification, V&V and
Integration• Focus on shrinking design cycle time• Design process?
3D-Duct : Problem Formulation
Entry Exit Location and shape (Given)
Optimum geometry of duct from Entry to Exit ?
Objective/Constraints
• Pressure Recovery• Distortion• Swirl
3D-Duct : Automation for CFD
Generation of entry and exit sections using GAMBIT
Clustering Parameters
Conversion of file format to CGNS using FLUENT
Mesh file
Generation of structured volume grid using parametrization
Duct Parameters(β1, β2, αy, αz)
Entry & Exit sections
Conversion of structured grid to unstructured format
Unstructured CGNS file
CFD Solution using FLUENT
End-to-end (Parameters to DC60)
automated CFD Cycle. Objective/Constraints evaluationUsing UDFs (FLUENT)
DC60
CFD Solution
ContinuationSolution
3D-Duct : Automation for Design
Generation of structured volume grid using parametrizationEntry & Exit
sections
Conversion of structured grid to unstructured format
CFD Solution using FLUENT
Objective/Constraints evaluationUsing UDFs (FLUENT)
DC60
Optimization
Duct Parameters(β1, β2, αy, αz)
ContinuationSolution
Unstructured CGNS file
CFD Solution
3D-Duct : Design Space Reduction
6.19
1.42
(0.61, 0.31, 1.0, 1.0)
Optimized duct from low fidelity rules
24.2116.28DC60
3.532.0PLOSS
(-0.4, 1.5, 0.3, 0.6)
(0.1, 0.31, 0.2, 0.6)
P
Highly infeasibleFrom low fidelity rules
Marginally infeasible from low fidelity rules
P – Parameters; PLOSS – Total Pressure Loss
3D-Duct : Simulation Time
• Strategies– Continuation Method– Parallel execution of FLUENT on a 4-noded
Linux cluster
Time for simulation has been reduced to around 20%.
0 20 40 60 80 100
Time (hrs)
Time per CFD Run
Serial
Parallel
Slapping
3D-Duct : Design Process
Parametrization
Low fidelity Analysis
DOE in reduced space
CFD analysis at DOE points
RS for PR & DC60
OptimizationConstraint
s
LFA Optima
CONCURRENT ENGINEERING Vs MDO
Time into the process
Source: AIAA MDO White Paper, 1991
Life Cycle Emphasis
Design
Manufacturing
Supportability
CE
Systems Design Emphasis Aerodynamics
Propulsion
Structures
Controls
MDO