PARAMETER OPTIMIZATION FOR AN INTERACTIVE AIRCRAFT DESIGN

AERO – AIRCRAFT DESIGN AND SYSTEMS GROUP

PARAMETER OPTIMIZATION FOR AN

INTERACTIVE AIRCRAFT DESIGN

Mihaela

Ni

ță

Hamburg University of Applied Sciences

Dieter Scholz

Hamburg University of Applied Sciences

10

th

_{European Workshop on Aircraft Design Education 2011}

Naples, Italy, 24-27.05.2011

EWADE 2011

Hochschule für Angewandte Wissenschaften Hamburg

Background



PreSTo – Preliminary Sizing Tool

was developed

at Hamburg University of Applied Sciences

http://PreSTo.ProfScholz.de



PreSTo is divided into several modules:

preliminary sizing, cabin and fuselage, wing, high lift,

empennage, landing gear, mass and CG, drag and

DOC calculation.



Right figure: one possibility of sequencing and

iterating these design steps

EWADE

Dipl.-Ing. Mihaela Nita 26.05.2011, Page 3

The Problem



Design

requirements

are given: landing distance, take-off distance, cruise Mach

number, ...



Other design

parameters

are required: aspect ratio, maximum lift coefficients, ...



The

best combination of design parameters

leading to a good design needs to be found.

The Solution



To

formally optimize

the

aircraft design

parameters and present these optimized values to

the users as a starting point.



To combine formal optimization with a subsequent

interactive and experienced driven

aircraft design.

The Starting Point



Two-dimensional optimization problem

:

thrust-to-weight ratio (for jets) versus wing

loading…



…

for five requirements

: landing distance,

take-off distance, second segment and missed

approach climb gradients and cruise Mach

number.

Application of a Formal Optimization Program



Optimus

®

_{was connected to the Excel preliminary sizing sheet from PreSTo. This made it}

possible

to optimize any design output parameter for any combination of design input

parameters

.



Optimus

®

_{by Noesis Solutions (Belgium) is a Process Integration and Design Optimization}

software. It bundles design exploration and numerical optimization methods.



The original Excel preliminary sizing sheet was

extended.

Thrust-to-weight ratio Wing Loading W MTO S m g m T MTO TO ⋅ Permissible region Landing Take-off Cruise Missed Approach Second Segment

EWADE

Dipl.-Ing. Mihaela Nita 26.05.2011, Page 5

Extensions of PreSTo



Incorporation of both benefits (L/D, SFC, …) and penalties (structural mass, drag, …). For

example:

Optimus

W

redesign

W

y

preliminar

OE

OE

m

m

m

m

=

_,

−

_,

+

_,

From thrust-to-weight

ratio, based on Loftin

Based on the parameters of the

redesigned baseline aircraft

From Torenbeek

Based on the parameters

found by Optimus

®

Extensions of PreSTo



Automation of the cruise line in the matching chart by adjusting the value of

V/V

_m

.



In this way we are sure that the

most demanding

requirements are met

in the same time

.



Implementation and testing of

different SFC calculation models

.

Thrust-to-weight ratio Wing Loading W MTO S m g m T MTO TO ⋅ Permissible region Landing Take-off Cruise Missed Approach Second Segment

EWADE

Dipl.-Ing. Mihaela Nita 26.05.2011, Page 7

SFC Calcullation Models



Mattingly 1996

where M is the Mach number at the engine inlet



Svoboda 2000

BPR

ref

T

T

M

TSCF

=

(

0

.

4

+

0

.

45

)

θ

,

θ

=

/

where

α

is

SFC Calcullation Models



Isikveren 2002

calibrated for BPR = 5.2 with k

₁

= 1.586 lb/lb.hr; k

₂

= -0.303; k

₃

= 8.40 X 10

-4

_{per FL;}

k

₄

= -0.760; k

₅

= 5.45 X 10

-4

_{lb/lb.hr.FL; k}

6

= -0.307 lb/lb.hr; k

7

= -9.54 X 10

-5

lb/lb.hr .FL;

k

₈

= 0.694 lb/lb.hr



Sforza 2004



Howe 2000

where

c

₁

=

0.85

N/Nh

for low

λ

(BPR)

and

c

₁

= 0.7

N/Nh

for high

λ

(BPR)

)

/

/

(

10

7

.

0

T

₅

lbm

h

lbf

TSCF

=

−

CR













_⋅

=

2

10

sin

3

.

14

TO₅

π

CR

T

T

EWADE

Dipl.-Ing. Mihaela Nita 26.05.2011, Page 9

SFC Calcullation Models



Herrmann 2010

necessary parametrs: BPR, OAPR, TET, ΔP/P and engine component efficiencies:

η

_ventilator

, η

_compressor

, η

_turbine

, η

_nozzle

, η

_inlet

, where

)

1

(

)

2

.

0

(

)

1

(

5

)

(

697

.

0

2 0

BPR

M

BPR

M

G

BPR

t

t

turbine ventilator compressor turbine ventilator nozzle compressor

SFC

+

⋅

−

⋅

⋅

⋅

⋅

+

⋅

⋅

⋅

+

⋅

⋅

−

−

⋅

⋅

=

η

η

η

η

η

η

η

χ

ϑ

φ

2 2 1 2 1

2

.

0

1

)

1

(

7

.

0

1

;

1

;

2

1

1

/

;

)

1

(

)

(

01

.

1

1

)

(

M

M

OAPR

M

t

T

G

inlet gasgen turbine compressor gasgen compressor

+

−

−

=

















−

⋅

=

⋅

−

+

=

=

























⋅

⋅

−

⋅

+

⋅

−

⋅

−

=

− −

η

η

ϑ

χ

κ

φ

η

η

φ

χ

ϑ

χ

η

η

χ

φ

κ κ κ κ

SFC Calcullation Models



Herrmann 2010

Known parameters:

Thrust, M, H, BPR,

Δ

P/P

Calculated parameters:

TET, OAPR,

η

_ventilator

,

η

_compressor

, η

_turbine

, η

_nozzle

χ

,

υ

,

ϕ

, G,

η

_inlet

,

η

_gasgen

Calculation model

SFC

Input parameters:

BPR, TET, OAPR,

Δ

P/P

η

_ventilator

, η

_compressor

, η

_turbine

, η

_nozzle

H, M

EWADE

Dipl.-Ing. Mihaela Nita 26.05.2011, Page 11

Selected Results



Tests were performed starting from the parameters of an

Airbus A320

redesigned as

closely as possible to the real aircraft.

Parameter

Symbol

Original

A320

Redesigned

A320

Deviation

Matching chart

Max. lift coefficient, landing

C

_L,max,L

-

2.9

-Max. lift coefficient, take-off

C

L,max,TO

-

2.07

-Mass ratio, landing-take-off

m

_ML

/m

_MTO

0.878

0.878

-Aspect ratio

A

9.5

9.5

-Max lift-to-drag ratio

L/D

_max

17.88

18.59

-By-Pass ratio

BPR

6

6

-Speed-to-speed minimum drag

V/V

_m

-

0.94

-Relative operating empty mass

m

_OE

/m

_MTO

0.550

0.551

-Mission fuel fraction

M

_ff

-

0.171

-Max. take-off mass

m

_MTO

73500 kg

71960 kg

-2.10 %

Max. landing mass

m

L

64500 kg

63180 kg

-2.05 %

Operating empty mass

m

_OE

40430 kg

39654 kg

-1.92 %

Fuel mass

m

F

12500 kg

12305 kg

-1.56 %

Wing area

S

_W

122.4 m

2

_{119.8 m}

2

_{-2.15 %}

Wing mass

m

_W

-

7037.4 kg

-Take-off thrust of one engine

T

_TO

11000 N

108965 N

-1.83 %

Fuel volume needed

V

_F

-

16.8 m

3

-Approach

Baseline aircraft redesigned

with PreSTo: A320

Single parameter variation:

C

_LmaxL

, C

_LmaxTO

, m

_ML

/m

_MTO

, BPR

,

nE, A

Coupled parameters variation

Additional parameters: the

fixed requirements set free:

M

, S

_LFL

, S

_TOFL

Parameters

Objectives

Minimum m

_MTO

Minimum m

_F

Minimum DOC

Minimum m

_F

/ V,

m

_MTO

/ V

EWADE

Dipl.-Ing. Mihaela Nita 26.05.2011, Page 13

Influence of

C

_LmaxL

and

C

_LmaxTO



C

_LmaxL

varied in the interval [1.9, 3.5]



C

_LmaxTO

= 80 % ∙

C

_LmaxL



The rest of the parameters were kept as for the A 320

coupled

0.27

0.275

0.28

0.285

0.29

0.295

0.3

1.9 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5

T/W

C

_LmaxL

Thrust-to-weight ratio, T/W as

a function of maximum lift

coefficient for landing

configuration, C

LmaxL

Influence of

C

_LmaxL

and

C

_LmaxTO

m

_MTO

[kg]

C

_LmaxL

Maximum take-off mass, m

MTO

as a function of maximum lift

coefficient for landing

configuration, C

LmaxL

63000

64000

65000

66000

67000

68000

69000

70000

1.9 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5

EWADE

Dipl.-Ing. Mihaela Nita 26.05.2011, Page 15

Influence of

C

_LmaxL

and

C

_LmaxTO

m

_W

[kg]

C

_LmaxL

Wing mass, m

W

as a function

of maximum lift coefficient

for landing configuration,

C

LmaxL

5600

6100

6600

7100

7600

8100

1.9 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5

Influence of

C

_LmaxL

and

C

_LmaxTO

S

_W

C

_LmaxL

Wing areq, S

W

as a function

of maximum lift coefficient

for landing configuration,

C

LmaxL

90

100

110

120

130

140

150

160

170

1.9 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5

EWADE

Dipl.-Ing. Mihaela Nita 26.05.2011, Page 17

Influence of

C

_LmaxL

and

C

_LmaxTO

L/D

C

_LmaxL

Lift-to-drag ratio, L/D

as a

function of maximum lift

coefficient for landing

configuration, C

LmaxL

16

16.5

17

17.5

18

18.5

19

1.9 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5

Influence of

C

_LmaxL

and

C

_LmaxTO

V/V

_m

C

_LmaxL

Wing mass, m

W

as a function

of maximum lift coefficient

for landing configuration,

C

LmaxL

0.8

0.9

1

1.1

1.2

1.3

1.9 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5

EWADE

Dipl.-Ing. Mihaela Nita 26.05.2011, Page 19

Influence of

C

_LmaxL

and

C

_LmaxTO

SFC

C

_LmaxL

Specific Fuel Consumption,

SFC

as a function of maximum

lift coefficient for landing

configuration, C

LmaxL

1.58E-05

1.59E-05

1.59E-05

1.60E-05

1.60E-05

1.61E-05

1.9 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5

13.4 % mass improvement

with a

C

_LmaxL

= 2.82

Influence of

m

_ML

/m

_MTO

m

_MTO

/S

_W

m

_ML

/m

_MTO

Wing loading, m

MTO

/S

W

as a

function of maximum landing

mass ratio, m

ML/

m

MTO

560

610

660

710

760

0.68

0.73

0.78

0.83

0.88

0.93

EWADE

Dipl.-Ing. Mihaela Nita 26.05.2011, Page 21

Influence of

m

_ML

/m

_MTO

m

_MTO

m

_ML

/m

_MTO

Maximum take-off mass, m

MTO

as a function of maximum

landing mass ratio, m

ML/

m

MTO

60000

70000

80000

90000

100000

110000

120000

0.68 0.7 0.72 0.74 0.76 0.78 0.8 0.82 0.84 0.86 0.88 0.9 0.92

Influence of both

m

_ML

/m

_MTO

and

C

_LmaxL

,

C

_LmaxTO

m

_ML

/m

_MTO

Variation of m

ML

/m

MTO

and

C

LmaxL

. Results shown are

m

MTO

(bubble diameter)

and T/W (color).

C

_LmaxL

1

0.9

0.8

0.7

1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 3.5

T/W

EWADE

Dipl.-Ing. Mihaela Nita 26.05.2011, Page 23

Influence of both

m

_ML

/m

_MTO

and

C

_LmaxL

,

C

_LmaxTO

m

_ML

/m

_MTO

Variation of m

ML

/m

MTO

and

C

LmaxL

. Results shown are

m

MTO

(bubble diameter)

and S

W

(color).

C

_LmaxL

1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 3.5

1

0.9

0.8

0.7

S

_W

Influence of both

m

_ML

/m

_MTO

and

C

_LmaxL

,

C

_LmaxTO

for

C

_LmaxL

= 2.61 and

m

_ML

/

m

_MTO

= 0.95

0.000 0.100 0.200 0.300 0.400 0.500 0.600 0.700 0 100 200 300 400 500 600 700 800 Th rus t-to -w e igh t ra ti o [-] Wing loading in kg/m² Matching Chart 2nd Segment Missed appr. Take-off Cruise Landing

17.9 % mass improvement

EWADE

Dipl.-Ing. Mihaela Nita 26.05.2011, Page 25

Influence of

BPR,

on the redesigned aircraft (i.e. with

C

_LmaxTO

= 2.07

)

m

_MTO

Maximum take-off mass,

m

MTO

as a function of BPR

BPR

1.8 % mass improvement

for

BPR

= 13.8

67000

68000

69000

70000

71000

72000

73000

2

4

6

8

10

12

14

Influence of

BPR,

with

C

_LmaxTO

= 80 % C

_LmaxL

of the redesigned aircraft, i.e.

C

_LmaxTO

= 2.32

m

_MTO

Maximum take-off mass,

m

MTO

as a function of BPR

BPR

14.1 % mass improvement

for

BPR

= 11.3

63000

63200

63400

63600

63800

64000

64200

64400

4

5

6

7

8

9

10

11

12

13

EWADE

Dipl.-Ing. Mihaela Nita 26.05.2011, Page 27

Influence of

BPR

with

C

_LmaxTO

= 2.07 , model Herrmann

m

_MTO

Maximum take-off mass,

m

MTO

as a function of BPR

BPR

11.5 % mass improvement

for

BPR

= 11.2

65000

65500

66000

66500

67000

67500

68000

4

6

8

10

12

14

Influence of

BPR ,

with

C

_LmaxTO

= 2.07 , model Herrmann

V

_CR

Cruise speed, V

CR

as a

function of BPR

BPR

224

226

228

230

232

234

236

238

4

6

8

10

12

14

EWADE

Dipl.-Ing. Mihaela Nita 26.05.2011, Page 29

Influence of

BPR ,

with

C

_LmaxTO

= 2.32 model Herrmann

m

_MTO

Maximum take-off mass,

m

MTO

as a function of BPR

BPR

19.7 % mass improvement

for

BPR

= 9.5

59000

59200

59400

59600

59800

60000

60200

60400

4

5

6

7

8

9

10

11

12

13

Influence of both

BPR

and

C

_LmaxL

,

C

_LmaxTO

, model Herrmann

BPR

C

_LmaxL

Variation of BPR and

C

LmaxL

. Results shown are

m

MTO

(bubble diameter)

and m

F

(color).

20.0 % mass improvement

for

BPR

= 10.6 and

C

_LmaxL

=

3.13

14

11

8

4

1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 3.5

m

_F

EWADE

Dipl.-Ing. Mihaela Nita 26.05.2011, Page 31

Influence of both

BPR

and

M,

with

C

_LmaxTO

= 2.32,

model Herrmann

M

BPR

Variation of BPR and M.

Results shown are m

MTO

(bubble diameter) and m

F

(color).

15.7 % mass improvement

for

BPR

= 7.6 and

M

= 0.86

0.9

0.8

0.7

0.6

0.5

0.4

4 5 6 7 8 9 10 11 12 13 14 15

m

_F

Influence of

BPR

,

M, C

_LmaxL

and

m

_ML

/m

_MTO

model Herrmann

Objective: min m

_MTO

/ V

17.4 % mass improvement

for

BPR

= 10.7,

M

= 0.76,

C

_LmaxL

=2.53, m

_ML

/m

_MTO

=

EWADE

Dipl.-Ing. Mihaela Nita 26.05.2011, Page 33

Outlook



To question additional parameter variations for innovative configurations (

S

_TOFL

, S

_LFL

)



To test further objective functions:

DOC

,

m

_F

,

m

_F

/V

,

m

_MTO

/V



To include the nacelle drag penalty and landing gear weight penalty for high BPR



The final goal is to offer formal optimization of aircraft design parameters as a starting

point for further interactive parameter changes in PreSTo

independent from a commercial

tool like Optimus

®

_.



This shall be achieved by programming a suitable optimization algorithm with VBA in

PreSTo. The user can then "on pressing a button" find a "pre-optimized" design in the

preliminary sizing module.



This "pre-optimized" design can then be manually improved and made ready for airline

operation considering further expert knowledge.

Thank you!

[email protected]

http://PreSTo.ProfScholz.de

http://OPerA.ProfScholz.de

Contact

Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences