exploration of distributed propeller regional aircraft design · exploration of distributed...

Exploration of distributed propeller regional aircraft design

Baizura Bohari1,2, Emmanuel Benard1, Murat Bronz2

1University of Toulouse - ISAE Supaero, Dept. of Aeronautic andSpace Vehicles Design (DCAS)

2University of Toulouse - ENAC, UAV Laboratory F-31055

10 juillet 2018

Baizura Bohari (ISAE/ENAC) 5th Drone Garden Workshop 2018 10 juillet 2018 1 / 43

Outline

1 IntroductionThe big picture

2 Multidisciplinary Design Analysis (MDA)General frameworkFixed-wing Aircraft Sizing Tool - FAST

3 Aerodynamic ModuleModeling Frameworks

4 Verification and Synthesis ResultsValidation - Aerodynamic modelPropeller-Wing Interaction -LinearPropeller-Wing Interaction - Non-linear with high lift deviceValidation - FAST

5 Conclusions and Future WorksConclusionsFuture Works

6 References


Plan

1 Introduction

2 Multidisciplinary Design Analysis (MDA)

3 Aerodynamic Module

4 Verification and Synthesis Results

5 Conclusions and Future Works

6 References


Plan

1 IntroductionThe big picture


Distributed Propellers Aircraft Concept

FIGURE 1 – ESAero NASA X-57 Maxwell [2] 1FIGURE 2 – Vahana, the self-piloted, EVTOLAircraft from A3 by Airbus. 2

Features :- Multiple propellers distributed along the

wing span

- OEI condition less stringent

- Wing area reduced/Shorter Takeoff FieldLength

- High CL,max

Issues : Unconventional configuration- No semi-empirical formula

- Need cheap prediction tools ) low fidelity

1. NASA Illustration, Scalable Convergent Electric Propulsion Technology Operations Research (SCEPTOR) project,https://www.nasa.gov/centers/armstrong/features/CAS_showcase.html, Feb 2017

2. Vahana, the self-piloted, EVTOL Aircraft from A3 by Airbus, https://www.airbus.com, Jun 2018


https://www.nasa.gov/centers/armstrong/features/CAS_showcase.html

https://www.airbus.com

Transformation

Objectives :Determine the viability of a concept andoptimize it in a limited domainMonitor a large number of parameters andinteraction between disciplines

Estimate the aircraft performance for agiven mission

Reduce the number of late modifications

Expected outcomes :New weight distribution

Propellers-wing interaction,Propellers-control surfaces interaction

Specific modules integration


Transformation

Objectives :Determine the viability of a concept andoptimize it in a limited domain

Monitor a large number of parameters andinteraction between disciplines

Estimate the aircraft performance for agiven mission

Reduce the number of late modifications

Expected outcomes :New weight distribution

Propellers-wing interaction,Propellers-control surfaces interaction

Specific modules integration


Plan

1 Introduction





6 References


Plan



Framework

General multidisciplinary analysis framework[3] 3

AircraftDesign

Variables

Missionrequirements

0, 5!1:MDO:

Optimization

1:Fuel weight

t

SFC

t

2:Total weight

t

Load

t

3:Lift

t

Drag

t

Optimizedpropulsioncoe↵cients

5:SFC

1:Propulsionsystem

sizing andintegration

2:Propulsionmass/weight

3:Propulsion

powerand thrustcoe�cients

4:SFC

Optimizedmass/weightparameters

5:Total and fuel

weight

2:Mass/weight

analysis

3:Displacements

4:Total weightFuel weight

Optimizedaerodynamiccoe�cients

5:Lift and Drag

Load

3:Low,

Medium,Highfidelityanalysis

4:LiftDrag

Finaloperating

costs

4:MissionAnalysis

FIGURE 3 – Multidisciplinary design analysis workflow.

3. A.B. Lambe et al., Extensions to the Design Structure Matrix for the Description of Multidiplinary Design, Analysis, and Optimization Processes,Structural and Multidisciplinary Optimization, 2012


Plan



Fixed-wing Aircraft Sizing Tool - FAST

In-house multidisciplinary design analysis tool for aircraft with distributed propulsionsystem

Specific modules :Propulsion moduleGeometry initialization moduleAerodynamic moduleMass breakdown moduleGlobal flight and performance prediction module

Input :Top level aircraft requirements (TLAR)Aircraft geometry descriptionPropulsive parameters

Output :Mission profilesAircraft geometry sizingAerodynamic components’characteristicsWeight and balance


Fixed-wing Aircraft Sizing Tool (FAST)

Preliminary design tool (ONERA & ISAE-Supaero)[4] 4

Initial input

Wing sizing

Geometry

Aerodynamics and Weight estimation

Performance evaluation

xmlfile Vapproach

Npax

SMreq

Req. range, Cruise option Range, Mach, Altitude

0:Initiator 1 : PL(0), MTOW (0), MLW (0), MZFW (0), S

(0)w

1, 9æ2:MDA:FAST

2 : mt

f

, MLW t, Ct

L

max

3 : MTOW t 4 : Massest 9 : Massest, A/Ct, CL

(CD

)t, CL

(–)t

2:Wingsizing

3 : ywing

3:Compute

initialgeometry

4 : A/C(0)

A/C 9 : A/C4:

Resizegeometry

5 : A/C 6 : A/C

CL

(CD

), CL

(–) 9 : CL

(CD

), CL

(–)5:

Computeaerody-namics

7 : CL

(CD

), CL

(–)

Masses 9 : Masses

6:Massbreak-down

7 : Masses 8 : OWE

Sizing mission performances 9 : mf

7:Globalflight

8 : mf

, OWEm

9 : MTOW8:

UpdateMTOW

Operational mission performances9:

Opera-tional

mission

4. P. Schmollgruber et al., Use of a Certification Constraints Module for Aircraft Design Activities, AIAA Aviation Meeting, 2017


Plan

1 Introduction





6 References


State of the art

[Weiberg 1958]

! Wind tunnel test

! Twin-engine model with TE flap, high AR, thick and straight wing

[Witkowski 1988]

! Wind tunnel test

! Semi empirical ! Vortex Lattice

Method

[Veldhuis 2004]

! VLM-BEM model

! Navier-Stokes model

[Chatot 2014]

! Extended of steady actuator disk to unsteady flows

[Agostinelli 2015]

! RANS-Actuator Disk model combined with the BEMT

1958 1968

1988 2001

2004 2006

2014 2014

2015 2015

[Page 1968]

! Wind tunnel test

! Four propeller STOL transport aircraft

! Wing of various AR

[Moens 2001]

! Euler and 3D Navier Stokes

! Actuator Disk Model

[Hunsaker 2006]

! BET combined with Momentum Conservation equations

! Lifting Line Theory

[Ferraro 2014]

! Truckenbrodt 3D lifting surface method coupled with MSES

[Borer 2015]

! Blade shape profile and airfoil shape using MATLAB® and then fed into Xfoil

! Post-processing results with XROTOR

FIGURE 4 –


Plan

3 Aerodynamic ModuleModeling Frameworks


Proposed framework model

Op#mal

Update model

Wing variables

Propeller variables

Coupling design sensitivity analysis

STOP

POST-PROCESSOR

OpenVSP 3.9.1

Weight reduction

Lift/Drag distribution

Airfoil variables

MSES/Xfoil

Applicable requirements;

•  Take-off •  Climb-out •  Cruise

performance

Convergence delta CP, CL, CDi

Python / MATLAB

Optimization

Design changes

Blade Element Theory

Actuator Disk Theory Vortex Lattice Method

Lifting Line Theory

GEOMETRY MODELER

MATLAB

Python


Proposed framework model

FIGURE 5 – Workflow of aerodynamic module (linear)


Workflow

FIGURE 6 – Workflow of aerodynamic module (non-linear with high lift devices)


Propellers induced velocity

Propellers induced velocity :Uniform blade loadingFroude and Blade Element Theory

FIGURE 7 – Example of propellers induced velocities with the BET


Vortex Lattice Method

Reduced computational costs ) avoid chord-wise discretizationLift curve slope fixed by distance between vortex bound and collocation pointZero-lift angle in the VLM right-hand-side termAdditional mesh for defining the wake path [7] 5

FIGURE 8 – Classical VLM configuration FIGURE 9 – Modified VLM configuration

5. Yahyaoui, M. and al., Generalized Vortex Lattice Method for Predicting Characteristics of Wings with Flapand Aileron Deflection, International Journal of Mechanical, Aerospace, Industrial, Mechatronic andManufacturing Engineering ; Vol. 8, num. 10, 2014


Plan

1 Introduction





6 References


Plan



Test case - NASA TN D4448 [5] 6

TABLE 1 – Specifications of the model [5].

Dimension Shortwing span

Mediumwing span

Span, m 13.21 14.61Area, m2 30.6 32.8Mean aerodynamicchord, m

2.38 2.32

Aspect ratio 5.71 6.52Taper ratio 0.554 0.507NACA airfoil section 632-415 632-415Sweep of leadingedge, deg

2.88 2.88

Root chord, m 2.98 2.98Tip chord, m 1.65 1.51

FIGURE 10 – Geometry model [5]

6. Page et al., Large-scale wind-tunnel tests of a deflected slipstream STOL model with wings of variousaspect ratios, NASA TN D4448, 1968


Plan



CL � ↵ curves for three different tools

FIGURE 11 – Tc’ = 1.0 FIGURE 12 – Tc’ = 2.4


Lift and drag polars of medium wing span

FIGURE 13 – Tc’ = 3.8 FIGURE 14 – CL � CD curves for 3 Tc’


Lift and drag polars for short wing span

FIGURE 15 – Tc’=1.0


Lift and drag polars for short wing span

FIGURE 16 – Tc’=4.9


Plan



Aircraft - Smooth configuration - Propellers on

Angle of attack [deg]-10 -5 0 5 10 15 20

Lift

coeffic

ient

-1

-0.5

0

0.5

1

1.5

2

2.5Lift coefficient vs. angle of attack

NumericalExperimental

Drag coefficient0 0.1 0.2 0.3 0.4 0.5 0.6

Lift

coeffic

ient

-1

-0.5

0

0.5

1

1.5

2

2.5Lift coefficient vs. drag coefficient


FIGURE 17 – Full a/c configuration - no flaps - Tc = 0.90 - NACA TN 4365 [6] 7.

Validation of the model for propellers’ induced velocity : ✏%,cl,max = 8%No convergence for steep stall

7. Weiberg and al., Large scale wind-tunnel tests of an airplane model with an unswept, aspect-ratio 10 wing,two propellers and area-suction flaps, NACA TN 4365, 1958


Aircraft - High-lift configuration - Propellers on

Angle of attack [deg]-10 -5 0 5 10 15 20

Lift

coeffic

ient

0

0.5

1

1.5

2

2.5

3

3.5Lift coefficient vs. angle of attack


Drag coefficient0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

Lift

coeffic

ient

0

0.5

1

1.5

2

2.5

3

3.5Lift coefficient vs. drag coefficient


FIGURE 18 – Full a/c configuration - flaps 40� - Tc 0.75 - NACA TN 4365 [6] 11.

Lack of accuracy on ↵L,max , but not on cl,max : ✏%,cl,max = 1%

7. Weiberg and al., Large scale wind-tunnel tests of an airplane model with an unswept, aspect-ratio 10 wing,two propellers and area-suction flaps, NACA TN 4365, 1958


Plan



Test case - ATR 72-600

Number of passengers 70Range 825 NM

Cruise Mach number 0.4Approach speed 117.5 kts

TABLE 2 – Test case ATR 72-600 [1] 7

FIGURE 19 – Flight mission profile

Output ATR 72 FASTWing surface [m2] 61 61.1

Wing span [m] 27.05 27.08MPL [kg] 7850 7770OWE [kg] 12950 12801.8

MTOW [kg] 23000 24278.9MLW [kg] 22350 21801.9MFW [kg] 5000 4324.23

Mission fuel [kg] 2750.1 2689.1

TABLE 3 – Test case ATR 72-600 [1]

7. ATR 72-600, www.atr-aircraft.com/datas/download_center/27/fiche72_27.pdf/, Feb 2017Baizura Bohari (ISAE/ENAC) 5th Drone Garden Workshop 2018 10 juillet 2018 33 / 43

www.atr-aircraft.com/datas/download_center/27/fiche72_27.pdf/

Output

FIGURE 20 – Climb profile FIGURE 21 – Descent profile


Plan

1 Introduction





6 References


Plan



Conclusions

We have seen :Linear prediction of BVLM code in the presence of slipstream isvery well predicted and validatedThe effects of the spanwise variation of propeller thrust onlongitudinal characteristicsNon-linear with high lift device aerodynamic analysis for thepropeller wing interaction with a very minimum computational costsFAST has been validated for regional aircraft with conventionalpropulsive systems (A320 & ATR72-600)Aerodynamic module provides results good in agreement withexperimental measurements for preliminary design stepBoth FAST and aerodynamic module are able to take multiplepropellers along the wing

Limitations of aerodynamic module :High dependency in 2D aerodynamic dataPost-stall convergence if soft stall


Plan



Future Works

In the future :To integrate the updated specific modules, aerodynamic, mass, etc.with FASTTo continue with the MDO process focusing on the optimzation ofthe propeller numbers, location and size along the wing span.To expand the current aircraft model to hybrid electric configuration.


Thank you

- All models are wrong, and the value of any model is only to the extent to which itsupports the purpose for which it was built.- George E. P. Box


Plan

1 Introduction





6 References


References I

ATR.ATR 72-600.https://www.atr-aircraft.com/datas/download_center/27/

fiche72_27.pdf/.

NASA Illustration.Scalable convergent electric propulsion technology operations research (sceptor)project.https:

//www.nasa.gov/centers/armstrong/features/CAS_showcase.html,Available online since 11/4/15, consulted the 16/12/17.

Lambe, Andrew B. and Martins, Joaquim R. R. A.Extensions to the design structure matrix for the description of multidisciplinarydesign, analysis, and optimization processes.Structural and Multidisciplinary Optimization, 46(2) :273–284, 2012.

A. Sgueglia S. Defoort R. Lafarge N. Bartoli Y. Gourinat P. Schmollgruber,J. Bedouet and E. Benard.Use of Certification Constraints Module for Aircraft Design Activities.In AIAA Aviation Forum, number AIAA 2017-3762, 2017.


https://www.atr-aircraft.com/datas/download_center/27/fiche72_27.pdf/

https://www.atr-aircraft.com/datas/download_center/27/fiche72_27.pdf/



References II

V. Robert Page, Stanley O. Dickinson, and Wallace H. Deckert.Large-scale wind-tunnel tests of a deflected slipstream STOL model with wings ofvarious aspect ratios.Technical report, National Aeronautics and Space Administration, Washington, D.C., 1968.

Weiberg James A., Friggin Roy N. Jr.Florman Georges L. .Large scale wind-tunnel tests of anairplane model with an unswept, aspect-ratio10 wing, two propellers and area-suction flaps.NACA Technical Note, 4365, 1958.

M. Yahyaoui.Generalized vortex lattice method for predicting characteristics of wings with flapand aileron deflection.International Journal of Mechanical, Aerospace, Industrial, Mechatronic andManufacturing Engineering, 8(10), 2014.


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