Marseille, France,14-16 September 2004 WP1: NUMERICAL WHIRL-FLUTTER INVESTIGATION 1

ADYNADVANCED EUROPEAN TILTROTOR

DYNAMICS AND NOISE

Dr. Pierangelo MASARATI

Dipartimento di Ingnegneria AerospazialePolitecnico di Milano

30th European Rotorcraft ForumMarseille, France

September 14-16, 2004

NUMERICAL WHIRL-FLUTTER INVESTIGATIONOF THE EUROPEAN TILTROTOR CONCEPT:

CURRENT STATUS AND FUTURE PROSPECTS

Marseille, France,14-16 September 2004 WP1: NUMERICAL WHIRL-FLUTTER INVESTIGATION 2

Emanuele BianchiAgusta (I)

Anselmo RussoCIRA (I)

Fritz KießlingDLR (D)

Rogelio FerrerEurocopter (F)

Oliver DieterichEurocopter (D)

Consortium & Acknowledgments

Mauro FrosoniIDS (I)

Richard BakkerNLR (NL)

Vasilis RiziotisNTUA (GR)

Didier PetotONERA (F)

Massimiliano LanzPOLIMI (I)

Marseille, France,14-16 September 2004 WP1: NUMERICAL WHIRL-FLUTTER INVESTIGATION 3

EUROPEAN TILTROTOR CONCEPT

Marseille, France,14-16 September 2004 WP1: NUMERICAL WHIRL-FLUTTER INVESTIGATION 4

EUROPEAN TILTROTOR CONCEPT

� Nacelle tilting interconnected

� Outer portions of wing independently tiltable

Marseille, France,14-16 September 2004 WP1: NUMERICAL WHIRL-FLUTTER INVESTIGATION 5

ADYN description

WP1 Whirl-Flutter: Requirements and Preliminary CalculationsNumerical simulation of tiltrotor whirl flutter behaviourInvestigation on major design parameters Wind tunnel model requirements

WP2 Whirl-Flutter: Model Preparation and TestDesign and manufacture of a Dynamically-scaled half-span WT model Test campaign in a high speed WTValidation of computational tools with experimental database

WP3 Aeroacoustic Assessment and OptimisationWT tests of TILTAERO’ s rotor to explore its noise characteristicsDesign and manufacture of a new blade with improved noise characteristicsWT tests of the new blades Validation of computational tools with experimental database

WP4 High-Speed Performance AssessmentWT tests of rotors to measure and validate the performances

Marseille, France,14-16 September 2004 WP1: NUMERICAL WHIRL-FLUTTER INVESTIGATION 6

ADYN description

� Enhance the EU knowledge on tiltrotor technologies by deeply analyzing whirl-flutter

� Comparison of analytical and experimental results

� Tests of a half-span scaled model in high speed wind tunnel facilities

� The wind tunnel model will help optimize rotor blade design for low external noise

� The project will provide final recommendations for the design of a full-scale tiltrotor flight demonstrator (European Tiltrotor Concept)

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WP1 Whirl Flutter Task Objectives & Organization

WP 1: Whirl Flutter: Requirements & Preliminary Calculations

T 1.1: Mathematical modelsST 1.1.1: Preliminary WF and dynamic behavior prediction (C)ST 1.1.2: WT model stability and WF prediction (C)ST 1.1.3: Analysis of special aspects regarding WF (A)ST 1.1.4: WT model update and prediction of WF boundary (F)

T 1.2: Establishment of model requirements & variants to TILTAERO

WP 2: Whirl Flutter Model Preparation & Test

Marseille, France,14-16 September 2004 WP1: NUMERICAL WHIRL-FLUTTER INVESTIGATION 8

Software Tools

Partner Software Developed by Type

CIRA CIRANO CIRA MBDLR NASTRAN + ZAERO* Commercial FEMEC HOST EUROCOPTER Comp.ECD CAMRAD II Commercial Comp./MBIDS CAMRAD JA + NASTRAN Commercial Comp. + FEMNLR Flightlab Commercial Comp./MBNTUA GAST NTUA MBONERA HOST EUROCOPTER Comp.POLIMI DYMORE GaTech/POLIMI MB

MBDyn ( + NASTRAN) POLIMI MB ( + FEM)* Fixed wing only

Marseille, France,14-16 September 2004 WP1: NUMERICAL WHIRL-FLUTTER INVESTIGATION 9

Wing Design

movable wing actuators tube supports tube/nacelle actuator

nacelle

tube (outboard)movable wing fixed wing

tube (inboard)wing-fuselage connection

Marseille, France,14-16 September 2004 WP1: NUMERICAL WHIRL-FLUTTER INVESTIGATION 10

Wind Tunnel Model: Overview

Reflection Plane

DNW Closed Section Floor

Model Support Structure Fairing

Windmilling Rotor

Dynamically Scaled Wing

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Wind Tunnel Model: Nacelle Details

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Wind Tunnel Model Support

WT closed section floor

turn table

wind direction

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Numerical Model of the Rotor Hub

Multiple load path

Single load path

beamrigid

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Excitation System

Unbalanced mass

Motor 1Motor 2

Unbalanced mass

F1F2 Cres

2 counterrotating motorswith masses at 0 deg:beamwise excitation

Mass Summary:Motor: 1.3 Kg/motor Frames (aluminum):

8.6 KgAttachments: 1.8 Kg Max. rotating

masses: 1.6 Kg/motor

Total mass (max including frames): 16.6 Kg

Excitation forces:Max Flap excitation @ 6 Hz 150 N/motor 300 NMax Torsion excitation @ 12 Hz 600 N/motor 360 Nm

2 motors rotating in phasewith masses at 180 deg:

torsion excitation

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Excitation System (Cont.)

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Analyzed Configurations

Wing Blades Hub Nacelle

1 Full-scale European Tiltrotor Concept (ETRC)

2 Mach-scale ETRC

3 Mach-scale ETRC TILTAERO

4 Mach-scale ETRC TILTAERO ADYN

5 ADYN TILTAERO ADYN ADYN (overweight)

Marseille, France,14-16 September 2004 WP1: NUMERICAL WHIRL-FLUTTER INVESTIGATION 17

Whirl-Flutter Stability Results

Flight Speed - KTAS

Fre

quen

cy-H

z

0 100 200 300 400 5000

10

20

30

40

50

Elastic Rotor 1.0: Whirl Flutter

Flight Speed - KTAS

Dam

ping

0 100 200 300 400 500-0.2

0

0.2

0.4

0.6

0.8

1

Elastic Rotor 1.0: Whirl Flutter

Figure 1: Whirl flutter Mach scaled nacelle: critical mode: wing vertical bending (green)

Flight Speed - KTAS

Fre

quen

cy-

Hz

0 100 200 300 400 5000

10

20

30

40

50

Elastic Rotor 1.0: Whirl Flutter (Nacelle Overweight)

Flight Speed - KTAS

Dam

ping

0 100 200 300 400 500-0.2

0

0.2

0.4

0.6

0.8

1

Elastic Rotor 1.0: Whirl Flutter (Nacelle Overweight)

Figure 2: Whirl flutter overweight nacelle: critical mode: wing torsion (grey)

Mach-scale: critical mode is wing beam

Overweight nacelle: critical mode becomes wing torsion

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Model Design Issues

� Nacelle/hub mass is larger than Mach-scale

� Tailoring of the whirl-flutter mode to be wing beam

� Tailoring of the wing beam mode damping

� Wing will be stiffer than Mach-scale

� Kinematic/constitutive couplings are being investigated

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Future Work

� There are delays partially related to sibling projects

� Whirl-flutter tests in late 2005 in DNW (Marknesse)

� High-speed tests in early 2006 at ONERA (Modane)

� WP1/2 (and ADYN as a whole) is expected to proceed without further delays