constrained aero-elastic multi-point optimization using the … · 2013. 9. 24. · design the...
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www.DLR.de • Chart 1 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Constrained Aero-elastic Multi-Point Optimization Using the Coupled Adjoint Approach
M. Abu-Zurayk MUSAF II Colloquium 20th Sept. 2013, Toulouse
www.DLR.de • Chart 2 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Table of Contents
Ø Motivation
Ø Formulation of the Coupled Adjoint Approach
Ø Test Case Description
Ø Unconstrained Single-Point Optimization
Ø Constrained Single- and Multi-Point Optimizations
Ø Future Work: Gradient Correction due to Trimming Ø Conclusions
www.DLR.de • Chart 3 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Motivation
Ø During the flight, the wing deforms due to the aero-elastic effects.
Ø The aero-elastic deformation significantly modifies the wing shape (twist and bending) and impacts the aerodynamic coefficients
=> need to take them into account in the design phase.
Jig Shape
Flight Shape
Courtesy of Stefan Keye
www.DLR.de • Chart 4 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Motivation
Ø During the flight, the wing deforms due to the aero-elastic effects.
Ø The aero-elastic deformation significantly modifies the wing shape (twist and bending) and impacts the aerodynamic coefficients
=> need to take them into account in the design phase.
Jig Shape
Flight Shape
Courtesy of Stefan Keye
Ø The effect becomes more evident
towards the wing tip
www.DLR.de • Chart 5 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Motivation
Ø During the flight, the wing deforms due to the aero-elastic effects.
Ø The aero-elastic deformation significantly modifies the wing shape (twist and bending) and impacts the aerodynamic coefficients
=> need to take them into account in the design phase. Ø Several approaches for dealing with elasticity in wing design
Jig Shape
Flight Shape
www.DLR.de • Chart 6 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Motivation
Ø During the flight, the wing deforms due to the aero-elastic effects.
Ø The aero-elastic deformation significantly modifies the wing shape (twist and bending) and impacts the aerodynamic coefficients
=> need to take them into account in the design phase. Ø Several approaches for dealing with elasticity in wing design
Jig Shape
Flight Shape
1. Stiffer wing reduces the deformation (elastic effects)
www.DLR.de • Chart 7 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Motivation
Ø During the flight, the wing deforms due to the aero-elastic effects.
Ø The aero-elastic deformation significantly modifies the wing shape (twist and bending) and impacts the aerodynamic coefficients
=> need to take them into account in the design phase. Ø Several approaches for dealing with elasticity in wing design
Jig Shape
Flight Shape
…. BUT this increases the weight 1. Stiffer wing reduces the deformation (elastic effects)
www.DLR.de • Chart 8 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Motivation
Ø During the flight, the wing deforms due to the aero-elastic effects.
Ø The aero-elastic deformation significantly modifies the wing shape (twist and bending) and impacts the aerodynamic coefficients
=> need to take them into account in the design phase. Ø Several approaches for dealing with elasticity in wing design
Jig Shape
Flight Shape
…. BUT this increases the weight 1. Stiffer wing reduces the deformation (elastic effects)
2. Design the Fight shape and inversely compute the Jig shape
www.DLR.de • Chart 9 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Motivation
Ø During the flight, the wing deforms due to the aero-elastic effects.
Ø The aero-elastic deformation significantly modifies the wing shape (twist and bending) and impacts the aerodynamic coefficients
=> need to take them into account in the design phase. Ø Several approaches for dealing with elasticity in wing design
Jig Shape
Flight Shape
…. BUT this increases the weight 1. Stiffer wing reduces the deformation (elastic effects)
2. Design the Fight shape and inversely compute the Jig shape …. Requires experience …. What about multipoint ? Aeroelastic deformation is dependent on the flow condition (Mach, lift,…)
www.DLR.de • Chart 10 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Motivation
Ø During the flight, the wing deforms due to the aero-elastic effects.
Ø The aero-elastic deformation significantly modifies the wing shape (twist and bending) and impacts the aerodynamic coefficients
=> need to take them into account in the design phase. Ø Several approaches for dealing with elasticity in wing design
Jig Shape
Flight Shape
…. BUT this increases the weight 1. Stiffer wing reduces the deformation (elastic effects)
2. Design the Fight shape and inversely compute the Jig shape
3. Start with Jig shape and design Flight shape
…. Requires experience …. What about multipoint ? Aeroelastic deformation is dependent on the flow condition (Mach, lift,…)
www.DLR.de • Chart 11 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Motivation
Ø During the flight, the wing deforms due to the aero-elastic effects.
Ø The aero-elastic deformation significantly modifies the wing shape (twist and bending) and impacts the aerodynamic coefficients
=> need to take them into account in the design phase. Ø Several approaches for dealing with elasticity in wing design
Jig Shape
Flight Shape
…. BUT this increases the weight 1. Stiffer wing reduces the deformation (elastic effects)
2. Design the Fight shape and inversely compute the Jig shape
3. Start with Jig shape and design Flight shape …. Works for multipoint. However, requires coupled CFD-CSM simulations
…. Requires experience …. What about multipoint ? Aeroelastic deformation is dependent on the flow condition (Mach, lift,…)
www.DLR.de • Chart 12 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Motivation
Ø The aero-elastic equilibrium is obtained after several couplings between aerodynamics and structure and incurs high-computational cost => in case of optimization efficient strategies are required
Aerodynamics
Structure
Loads Deformations
www.DLR.de • Chart 13 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Motivation
Ø The aero-elastic equilibrium is obtained after several couplings between aerodynamics and structure and incurs high-computational cost => in case of optimization efficient strategies are required
Ø Gradient-based optimization algorithms are known to be efficient but computing the gradients is expensive with the standard finite differences approach.
Aerodynamics
Structure
Loads Deformations Loop over number of design variables
Design Variables
Gradients
Traditional Finite Differences Approach
www.DLR.de • Chart 14 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Motivation
Ø The aero-elastic equilibrium is obtained after several couplings between aerodynamics and structure and incurs high-computational cost => in case of optimization efficient strategies are required
Ø Gradient-based optimization algorithms are known to be efficient but computing the gradients is expensive with the standard finite differences approach.
=> need for an efficient approach to determine the gradients: the coupled aero-structural adjoint approach
Aerodynamics
Structure
Loads Deformations Loop over number of design variables
Design Variables
Gradients
Traditional Finite Differences Approach
Design Variables
Gradients
Coupled Aero-Structural Adjoint computation
Adjoint approach is independent on the
number of design variables
Coupled Adjoint Approach
www.DLR.de • Chart 15 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Formulation of the Coupled Adjoint Approach
www.DLR.de • Chart 16 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Components of the Coupled System
Ø Loose aero-structural coupling is employed at DLR
TAU ANSYS
www.DLR.de • Chart 17 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Components of the Coupled System
Ø Loose aero-structural coupling is employed at DLR
TAU ANSYS TAU
www.DLR.de • Chart 18 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Components of the Coupled System
Ø Loose aero-structural coupling is employed at DLR
TAU ANSYS TAU
www.DLR.de • Chart 19 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Components of the Coupled System
Ø Loose aero-structural coupling is employed at DLR
TAU
transfer loads from CFD mesh to CSM mesh using :
Linear Interpolation Tool
ANSYS TAU TAU
www.DLR.de • Chart 20 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Components of the Coupled System
Ø Loose aero-structural coupling is employed at DLR
TAU
transfer loads from CFD mesh to CSM mesh using :
Linear Interpolation Tool
ANSYS ANSYS TAU TAU
www.DLR.de • Chart 21 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Components of the Coupled System
Ø Loose aero-structural coupling is employed at DLR
TAU
transfer loads from CFD mesh to CSM mesh using :
Linear Interpolation Tool
ANSYS ANSYS TAU TAU
www.DLR.de • Chart 22 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Components of the Coupled System
Ø Loose aero-structural coupling is employed at DLR
TAU
transfer loads from CFD mesh to CSM mesh using :
Linear Interpolation Tool
ANSYS
transfer deformation from CSM mesh to CFD mesh using : Radial Basis Function
ANSYS TAU TAU ANSYS
www.DLR.de • Chart 23 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Components of the Coupled System
Ø Loose aero-structural coupling is employed at DLR
TAU
transfer loads from CFD mesh to CSM mesh using :
Linear Interpolation Tool
ANSYS
transfer deformation from CSM mesh to CFD mesh using : Radial Basis Function
ANSYS TAU TAU ANSYS
www.DLR.de • Chart 24 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Components of the Coupled System
Ø Loose aero-structural coupling is employed at DLR
TAU
transfer loads from CFD mesh to CSM mesh using :
Linear Interpolation Tool
ANSYS
transfer deformation from CSM mesh to CFD mesh using : Radial Basis Function
ANSYS TAU TAU ANSYS TAU ANSYS Jig Shape
Flight Shape
5 Couplings
www.DLR.de • Chart 25 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Formulation of the Coupled Adjoint Equations
Ø Motivation: Efficient computation of the gradient of a cost function (I) w.r.t the design parameters (D). Ø The aero-structural coupled system is defined by:
⎥⎦
⎤⎢⎣
⎡=uw
W
⎥⎦
⎤⎢⎣
⎡=RsRa
R
⎥⎦
⎤⎢⎣
⎡=TA
D
Aerodynamic residual Structural residual
Shape design variables
Structural deformation
Flow variables
Structural thickness
State variables Vector
Design variables Vector
Residual Vector I=I (W,D) ; R=R (W,D)=0
Where and are the aerodynamic and the structure Lagrange multipliers. aψ
The Coupled Adjoint Equation
The Gradients
⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
∂
∂∂
∂
−=⎭⎬⎫
⎩⎨⎧
⎥⎥⎥⎥
⎦
⎤
⎢⎢⎢⎢
⎣
⎡
∂
∂
∂
∂∂
∂
∂
∂
u
wψsψa
uRs
wRs
uRa
wRa
I
I
TT
TT
⎟⎟⎟⎟
⎠
⎞
⎜⎜⎜⎜
⎝
⎛
⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
∂∂
∂∂
∂∂
∂∂
⎭⎬⎫
⎩⎨⎧
+⎪⎭
⎪⎬
⎫
⎪⎩
⎪⎨
⎧
∂∂∂∂
=⎭⎬⎫
⎩⎨⎧=
⎭⎬⎫
⎩⎨⎧
TRs
ARs
TRa
ARa
ψsψa
T
ADD
T
T
TT
I
I
ddL
ddI
sψ
RIL Ψ+=Ø Define the Lagrange:
www.DLR.de • Chart 26
Test case description
Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
www.DLR.de • Chart 27 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Test Case Description
Ø Wing-Body configuration based on the DO728 geometry used as a test case. Ø Reynolds number : 21e06 Ø Lift is kept constant by varying angle of attack (implicit lift constraint à requires gradient correction)
Ø CFD Ø One-Equation turbulence model Spalart-Allmaras
www.DLR.de • Chart 28 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Test Case Description
Ø Wing-Body configuration based on the DO728 geometry used as a test case. Ø Reynolds number : 21e06 Ø Lift is kept constant by varying angle of attack (implicit lift constraint à requires gradient correction)
Ø CFD Ø One-Equation turbulence model Spalart-Allmaras Ø CFD structured mesh; 1.2 Million nodes
www.DLR.de • Chart 29 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Test Case Description
Ø Wing-Body configuration based on the DO728 geometry used as a test case. Ø Reynolds number : 21e06 Ø Lift is kept constant by varying angle of attack (implicit lift constraint à requires gradient correction)
Ø CFD Ø One-Equation turbulence model Spalart-Allmaras Ø CFD structured mesh; 1.2 Million nodes Ø Parameterization: 30 parameters fixing the body 150/2 FFD parameters on the wing (implicit thickness constraint)
www.DLR.de • Chart 30 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Test Case Description
Ø Wing-Body configuration based on the DO728 geometry used as a test case. Ø Reynolds number : 21e06 Ø Lift is kept constant by varying angle of attack (implicit lift constraint à requires gradient correction)
Ø CFD Ø One-Equation turbulence model Spalart-Allmaras Ø CFD structured mesh; 1.2 Million nodes Ø Parameterization: 30 parameters fixing the body 150/2 FFD parameters on the wing (implicit thickness constraint)
dAdC
ddC
ddC
dAdC
dACd LLDDD )/(Liftconstant @)(
αα−=
www.DLR.de • Chart 31 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Test Case Description
Ø Wing-Body configuration based on the DO728 geometry used as a test case. Ø The Structure model: 27 Ribs 2 Spars
Lower & Upper Skin
www.DLR.de • Chart 32 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Test Case Description
Ø Wing-Body configuration based on the DO728 geometry used as a test case.
Ø The Structure model: 27 Ribs 2 Spars
Lower & Upper Skin Ø CSM Ø The CSM mesh:
4000 nodes. Modeled using rectangular shell elements, each node has 6 DOFs.
www.DLR.de • Chart 33 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Optimizations
www.DLR.de • Chart 34 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Optimizations
Ø Three optimizations were performed
www.DLR.de • Chart 35 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Optimizations
Ø Three optimizations were performed
Ø 1. Unconstrained Single-point optimization at the design point
CL
Mach
0.417
0.500
0.340
0.80 0.82 0.78
www.DLR.de • Chart 36 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Optimizations
Ø Three optimizations were performed
Ø 1. Unconstrained Single-point optimization at the design point Ø 2. Constrained Single-point optimization at the design point
CL
Mach
0.417
0.500
0.340
0.80 0.82 0.78
www.DLR.de • Chart 37 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Optimizations
Ø Three optimizations were performed
Ø 1. Unconstrained Single-point optimization at the design point Ø 2. Constrained Single-point optimization at the design point Ø 3. Constrained Multi-Point Optimization
CL
Mach
0.417
0.500
0.340
0.80 0.82 0.78
www.DLR.de • Chart 38 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Optimizations
Ø Three optimizations were performed
Ø 1. Unconstrained Single-point optimization at the design point Ø 2. Constrained Single-point optimization at the design point Ø 3. Constrained Multi-Point Optimization
Ø The objective is drag reduction at constant CL and wing thickness. (Aerodynamic objective with elastic effects taken into account)
CL
Mach
0.417
0.500
0.340
0.80 0.82 0.78
www.DLR.de • Chart 39 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Unconstrained Single-point Optimization
Ø The optimization employed a quasi-Newton gradient-based algorithm.
www.DLR.de • Chart 40 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Unconstrained Single-point Optimization
Ø The optimization employed a quasi-Newton gradient-based algorithm. Ø Optimization converged after 41 aero-structural couplings
and 25 coupled adjoint computations. Ø The optimization reduced the drag by 15 drag counts
while keeping the lift and the thickness constant.
www.DLR.de • Chart 41 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Unconstrained Single-point Optimization
Optimized Baseline
Ø The optimization employed a quasi-Newton gradient-based algorithm. Ø Optimization converged after 41 aero-structural couplings
and 25 coupled adjoint computations. Ø The optimization reduced the drag by 15 drag counts
while keeping the lift and the thickness constant.
www.DLR.de • Chart 42 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Unconstrained Single-point Optimization
Ø The optimization employed a quasi-Newton gradient-based algorithm. Ø Optimization converged after 41 aero-structural couplings
and 25 coupled adjoint computations. Ø The optimization reduced the drag by 15 drag counts
while keeping the lift and the thickness constant.
Baseline Optimized
www.DLR.de • Chart 43 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Unconstrained Single-point Optimization
η=0.45
η=0.55 η=0.75
η=0.25
Op+mized
Baseline
www.DLR.de • Chart 44 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Unconstrained Single-point Optimization
www.DLR.de • Chart 45 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Unconstrained Single-point Optimization
This (at constant lift) increases the bending moment at the Wing’s root Keep CMx constant during the aero-elastic optimization
www.DLR.de • Chart 46 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Constrained Single-point Optimization
Ø The optimization employed SQP gradient-based algorithm. Ø Optimization converged after 31 aero-structural couplings
and 19 coupled adjoint computations. Ø The optimization reduced the drag by 13 drag counts
while keeping the lift and the thickness constant.
www.DLR.de • Chart 47 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Constrained Single-point Optimization
Ø The optimization employed SQP gradient-based algorithm. Ø Optimization converged after 31 aero-structural couplings
and 19 coupled adjoint computations. Ø The optimization reduced the drag by 13 drag counts
while keeping the lift and the thickness constant.
www.DLR.de • Chart 48 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Constrained Single-point Optimization
Ø The optimization employed SQP gradient-based algorithm.
www.DLR.de • Chart 49 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Constrained Multi-point Optimization
Ø The points were equally weighted.
∑=
=5
1
*2.0ionCost_Functi
DiC
CL
Mach
0.417
0.500
0.340
0.80 0.82 0.78
www.DLR.de • Chart 50 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Constrained Multi-point Optimization
Ø The points were equally weighted.
∑=
=5
1
*2.0ionCost_Functi
DiC
Mach 0.80 0.82 0.78
CL
0.417
0.500
0.340
www.DLR.de • Chart 51 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Constrained Multi-point Optimization
Ø The points were equally weighted.
∑=
=5
1
*2.0ionCost_Functi
DiC
Mach 0.80 0.82 0.78
Constraint applied on design point only
CL
0.417
0.500
0.340
www.DLR.de • Chart 52 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Constrained Multi-point Optimization
Ø The points were equally weighted.
∑=
=5
1
*2.0ionCost_Functi
DiC
Mach 0.80 0.82 0.78
Highest gradients bring highest change (drag reduction)
CL
0.417
0.500
0.340
Ø 25 design iterations
Ø 20 gradient computations
Ø 260 hrs on 48 processors
www.DLR.de • Chart 53 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Constrained Multi-point Optimization
Ø The points were equally weighted.
∑=
=5
1
*2.0ionCost_Functi
DiC
Mach 0.80 0.82 0.78
Highest gradients bring highest change (drag reduction)
-7
CL
0.417
0.500
0.340
Ø 25 design iterations
Ø 20 gradient computations
Ø 260 hrs on 48 processors
-5 drag counts
-7 -32
-22
www.DLR.de • Chart 54 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Constrained Multi-point Optimization
Ø The points were equally weighted.
∑=
=5
1
*2.0ionCost_Functi
DiC
Highest gradients bring highest change (drag reduction)
Ø 25 design iterations
Ø 20 gradient computations
Ø 260 hrs on 48 processors
www.DLR.de • Chart 55 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Constrained Multi-point Optimization
www.DLR.de • Chart 56 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Constrained Multi-point Optimization
www.DLR.de • Chart 57 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Future Work: Gradient Correction due to Trimming
Ø Trimming the flight with a horizontal tailplane (to reach a target pitching moment) will be considered during the Optimization.
Ø The gradients of our cost function need to be corrected if the flight is trimmed using horizontal tailplane. (similar to correcting gradients of drag when running for target lift).
Ø Use the Lagrange formulation to predict the correction term in the gradients.
www.DLR.de • Chart 58 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Ø Trimming the flight with a horizontal tailplane (to reach a target pitching moment) will be considered during the Optimization.
Ø The gradients of our cost function need to be corrected if the flight is trimmed using horizontal tailplane. (similar to correcting gradients of drag when running for target lift).
Ø Use the Lagrange formulation to predict the correction term in the gradients. Ø If our cost function is drag then:
Correction Term
"↓$ : far-field angle of attack "↓& : tail’s angle of incidence
Future Work: Gradient Correction due to Trimming
www.DLR.de • Chart 59 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Ø Tested on 2D Euler case
Future Work: Gradient Correction due to Trimming
www.DLR.de • Chart 60 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Ø Tested on 2D Euler case
Future Work: Gradient Correction due to Trimming
www.DLR.de • Chart 61 Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013
Conclusions
Ø The coupled aero-structural adjoint approach was employed to efficiently obtain the gradients employed in single- and multi-point aero-elastic optimizations.
Ø The approach employs DLR’s TAU code to solve the flow equations and ANSYS Mechanical to solve the structure equations, and deals with inviscid as well as viscous turbulent flows.
Ø The coupled adjoint approach could save around 75% of computational time, which makes it now possible to perform aero-elastic optimizations using the gradient-based techniques, even for multi-point optimizations.
Ø A single- and multi-point optimizations with constrained rolling moment were performed and expected to have better effect on the structure (less weight).
Ø Future optimizations will include aerodynamic to structure cross sensitivities
Ø Future optimizations will include (horizontal tail) trimming effect
www.DLR.de • Chart 62
THANK YOU FOR YOUR ATTENTION
Aero-elastic Multi-point Optimization, M.Abu-Zurayk, MUSAF II, 20.09.2013