The Flow Control and Shape Optimization, Różne lotnicze
[ Pobierz całość w formacie PDF ]
The Flow Control and Shape Optimization
program at FOI
Olivier Amoignon, Mattias Chevalier, Ardeshir Hanifi, Jan Pralits
FOI (Swedish Defence Research Agency)
In collaboration with
Linné Flow Centre and Mechanics, Royal Institute of Technology (KTH), Sweden
KATnet II - Drag Reduction Workshop, 14th – 16th October 2008, Ascot, UK
Topics
Accurate simulation tools for concept design
Adjoint-based optimization
Wave drag reduction
Viscous drag reduction
Applications
Transonic Natural and Hybrid Laminar Flow design (ALTTA)
Transonic multipoint airfoil design (CESAR)
High Aspect Ratio Low Sweep wing design (NACRE)
Low speed laminar airfoil design (CESAR)
Work in progress
References (reports & articles)
Accurate simulations in the conceptual design phase ?
Some objectives
Control the laminar-to-turbulent transition at cruise design
Control the flow separation in high-lift configurations
Include static aeroelastic effects in 3D shape optimization
Include mass flow interaction in the wing/fuselage design
Concept design
Large variations of the parameters
Large design space (many parameters)
KTH/FOI approach
Gradient optimization using optimal control theory (“adjoint methods”)
Adjoint-based gradient computation
Gradient-based optimization
Faster convergence than statistical methods (genetic algorithms …)
Accurate resolution of the constraints (each design can be made
feasible)
Convergence speed independent of number of design parameters
Adjoint-based gradient computation (=optimal control approach)
Cost efficient (independent of number of design parameters)
Accurate (finite differences suffer from round-off errors)
CFD
(Edge)
Flow
solver
Adjoint
Flow
solver
Gradient computation
of one functional
Prepro-
cessing
Adjoint
Prepro-
cessing
Mesh
algorithm
Optimization
AESOP
Adjoint
Mesh
algorithm
Mesh
algorithm
Shape
parameterization
Adjoint
Shape
parameterization
Optimizer
”adjoint” of explicit mappings
=
transposed-Jacobian x gradient vector
Adjoint
Flow
solver
Flow
solver
Adjoint
Prepro-
cessing
Prepro-
cessing
Adjoint
Mesh
algorithm
Adjoint
Shape
parameterization
Shape
parameterization
Optimizer
[ Pobierz całość w formacie PDF ]