FAA CENTER OF EXCELLENCE FOR ALTERNATIVE JET FUELS & ENVIRONMENT

Project manager: Rick Riley, FAALead investigator: Kenneth S. Brentner, Penn State

Rotorcraft Noise Abatement Operating Conditions Modeling

ASCENT 6

Advisory Committee MeetingOctober 13-15, 2015

Seattle, WA

Opinions, findings, conclusions and recommendations expressed in this material are those of the author(s)and do not necessarily reflect the views of ASCENT sponsor organizations.

2

Motivation

• Rotorcraft noise becoming an increasingly larger issue

with general public– HAI’s “Fly Neighborly Guide” helpful for community noise

• Since publication, new rotorcraft and operations have been developed

– Need for more detailed data and information about noise produced

from the operation of rotorcraft

– Need for detailed and specific noise abatement procedures

• This project is to investigate noise abatement flight

procedures of rotorcraft through modeling– Physics based modeling of noise leveraging previous research

performed for NASA and DoD

– Comprehensive modeling of the many sources of rotor noise

– Complete vehicle modeling during example flight procedures • Flyover

• Approach, departure

• Turn maneuvers, etc.

3

Objectives

• Long-term

– Develop rotorcraft noise abatement procedures

– Demonstrate the ability of physics based modeling to provide vehicle noise data for advanced technology vehicles

• Near term (next 6 months)– Objective 1: Develop abatement procedures and flight test plan

• Complete noise predictions for S-76C+ helicopter

• Finalize flight test plan

– Objective 2: Provide vehicle noise data for notional vehicles with advanced technology (for AEDT)

• Finish PSU-WOPWOP templates and post processing for AEDT noise inputs

• Perform noise prediction for Bell 430 aircraft and compare predicted NPD and spectral class data with currently available data

• Demonstrate capability with notional advanced rotorcraft configurations

4

Outcomes and Practical Applications

• Outcomes– Validation of rotorcraft noise prediction system– Development of rotorcraft noise abatement procedures

• Methodology to propose and test potential procedures• Procedures

– Development of flight test plan to validate procedures– Prediction of noise data from advanced technology vehicles

(relevant for potential AEDT use)

• Practical applications– Demonstrate the value and ability of physics based tools for the

development of flight procedures• For rotorcraft manufacturers• For Government (FAA)

– This capability will provide data for AEDT and related tools• For system wide impact considerations• For users that need to understand the noise implications, but are not

rotorcraft experts (i.e., regulatory bodies, airports, consultants, academia, etc.)

5

Approach

• Couple and validate noise prediction system: flight simulation (HeloSim) + rotor wake and airloads (CHARM) + rotor noise (PSU-WOPWOP)

• Use noise prediction system to test and refine abatement procedures

• Develop flight test plan to validate noise abatement procedures

• Demonstrate noise prediction capabilities for notional advanced technology rotorcraft

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Schedule:

Status:

• Noise prediction system assembled and validated– Validated with Bell 430 flight test data[1] – good agreement– Simple comparison of operations and how noise is abated

• Flight test plan development underway

• Developing post processing needed to provide AEDT inputs

Schedule and Status

0 3 6 9 12 15 18

Set up noise prediction system

Perform validation noise computations

Evaluate abatement procedures

Develop flight test plan

Review input for AEDT & develop post processing

Develop notional advanced configurations

Predict advanced configurations' noise

Objective 1: Develop abatement procedures and flight test plan

Objective 2: Provide vehicle noise data for notional vehicles with advanced technology

Month

7

Recent Accomplishments and Contributions (1 of 3)

• Validation of noise prediction system: Bell 430 flight data

– 80 kts level flight• All noise sources (except engine)• OASPL agrees well, except uprange• Uprange underprediction common

– 3 deg descent (100 kts – mild BVI)• BVI peaks predicted• Amplitude of BVI peaks low

(probably due to small trim difference)

4-bladed MR; 2-bladed TR

Flight test data

Predicted

Observer Time (s)

To

talA

co

us

tic

Pre

ss

ure

(Pa

)

0.05 0.1 0.15 0.2-2

-1

0

1

2

3

4

BVI from test data

Predicted BVI

Observer time, (s)

8

Recent Accomplishments and Contributions (2 of 3)

• Noise predictions made for Bell 430 helicopter

– Changes in altitude• Noise reduces below helicopter as altitude increases• Along the sidelines, noise does not reduce significantly (and may

increase)

– Reduction in forward speed• EPNL reduces along sidelines; only small effect centerline (due to

increased duration of flyover time)

Altitude Sweep Speed Sweep

EPNL Contours

100 kts, 150 m

baseline

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Recent Accomplishments and Contributions (3 of 3)

– Descent angle

• SEL levels higher for 6 deg than 3 deg descent (BVI & distance)

– Climb angle

• SEL changes primarily due to distance changes6 deg

climb

3 deg

climb

Level

flight

Y location, ft

6 deg

descent

3 deg

descentLevel

flight

Y location, ft

(350m)

(150m)

Distance is the

same on these

lines

350 m

150 m

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Interfaces and Communications

• External– Conference paper: Li, Y.; Brentner, K.S.; Wachspress, D.A.;

Horn, J.F.; Saetti, U.; and Sharma, K., “Tools for Development and Analysis of Rotorcraft Noise Abatement,” presented at AHS “Sustainability 2015,” Montreal, Sept 22-24, 2015.

– Juliet Page and David Senzig, VOLPE (especially helpful in our AEDT input development)

– Penn State Vertical Lift Research Center of Excellence

– U. S. Army

– NASA

• Within ASCENT– None at this time

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Summary

• Summary statement– Physics-based noise prediction system has been formed from

previously existing tools– Bell 430 noise predictions validated with flight test data– Analysis of the impact of simple operational changes on noise has

been performed: altitude, speed, descent angle, climb angle– Flight test plan development underway– Prediction of input data for AEDT in progress

• Next steps?– Finish S-76C+ computations– Pick notional advanced configuration– Compute NPD curves and spectral class for Bell 430 and

advanced configuration

• Key challenges/barriers– Complex problem with several tools (but we are the developers

of most of those tools)– Short time to accomplish (but we have a GREAT team!)

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References

Contributors

[1] Watts, M. E.; Greenwood, E.; Smith, C. D.; Snider, R.; and Conner, D. A.; “Maneuver Acoustic Flight Test of the Bell 430 Helicopter Data Report,” NASA/TM–2014-218266, May 2014.

• PI: Kenneth S. Brentner, The Pennsylvania State University (PSU)• Co-Pis: Daniel Wachspress (CDI); Joseph F. Horn (PSU)• Students:

• Yaowei Li (MS, graduated Aug 2015)• Willca Villafana (MS, expected graduation Aug 2016)• Umberto Saetti (MS, expected graduation Aug 2016)

• Industrial Partners: • Continuum Dynamics, Inc. (CDI)• Bell Helicopter Textron, Inc. (BHTI) – Ben Goldman• Sikorsky Aircraft Corporation (SAC) – Eric Jacobs