Overview of NASA Vertical Lift Noise Research and Facilities

Transcription

1 National Aeronautics and Space Administration Overview of NASA Vertical Lift Noise Research and Facilities Susan A. Gorton Project Manager, Revolutionary Vertical Lift Technology April 20-21, 2017 Aircraft Noise and Emissions Reduction Symposium Alexandria, VA

2 Outline NASA Vision and Strategy for Vertical Lift NASA Acoustics Research NASA Acoustic Facilities Summary and Web References 2

3 Aeronautics Research Mission Directorate Strategic Implementation Plan (SIP) Community Vision Community Outcomes Research Themes Link to SIP: Roadmaps for each of the six Thrusts in the SIP have been developed: 3

4 Envisioned Common Civil Configurations and Missions in 2030 & beyond Conventional helicopters perform specific missions today, as shown in the black text. New vehicles will expand the missions of vertical lift vehicles across the size spectrum. Autonomous capability in varying degrees will be applied across the spectrum to enable new missions Missions Overarching Vertical Lift Strategy Very Light Light Medium Heavy UltraHeavy Inspection Photography Filming Spraying Mapping Weather Surveillance Delivery Police Training Traffic/news Power line service Spraying Personal Air Taxi Cargo Police EMS Traffic/news Tourism Executive Charter Oil Platforms SAR Cargo autonomous capability Oil platforms Disaster relief Cargo Logging Construction Firefighting Commuter (30 pax) Commercial transport ( pax) Disaster relief Civil reserve aircraft fleet Cargo Enable a broad expansion of vertical lift applications Improve current configuration cost, speed, payload, safety, and noise Open new markets with new configurations and capability Capitalize on convergence of technology in electric propulsion, autonomy and flight controls Blue Highlight: New mission and/or new configuration Link to SIP: 4

5 Notional NASA Vertical Lift Acoustics Roadmap FY16 FY17 FY18 FY19 FY20 FY21 Helicopters UAS/ Drones Electrified Aircraft Initial optimization demo Phase 2 optimization demo Validate low noise flight ops Phase 3 optimization demo Validation of analysis methods Validate low noise flight ops Acquire validation data (flight or laboratory) Initial optimization demo Validate low noise flight ops Develop semi-empirical and 1 st principle methods Develop low noise flight operation profiles Develop optimization methods Develop human response methods and metrics 5

6 NASA Acoustics Research for Vertical Lift Acoustics has been a major investment area for every NASA rotorcraft project for several decades Source noise physics Flight aeroacoustics Rotorcraft noise mitigation science Cabin noise Human response to noise NASA investment in tools and hardware WOP-WOP Rotorcraft Noise Model (RNM) ANOPP2 (Aircraft NOise Prediction Program 2nd Gen) Coupling CAMRADII/OVERFLOW/ANOPP2 FRAME (Fundamental Rotorcraft Acoustic Modeling from Experiments) Flight acoustic hardware (Wireless microphone system, vans, weather station) Wind tunnel acoustics treatment (14x22 upgrade, NFAC treatment) Exterior Effects Room upgrades for human response testing Measured Predicted Freestream Rotor disk 6

7 Demonstration of Design and Flight Operation Methods for Reduced VTOL Aircraft Noise Impact (FY19 Completion) Objective Develop, demonstrate, and validate optimization and noise reduction methods that enable 50% reduction in the area defined by the 70dB contour of Sound Exposure Level (SEL) footprint area of a rotary wing vehicle through a combination of rotor/vehicle design, flight operation methods and understanding the human response to rotorcraft noise. Flight Test Technical Areas and Approaches 3 Elements to the Approach Flight Operations (likely near term benefits) Design for Low Noise (likely mid and far term benefits) Human Perception (can be used to assess success of design and ops methods) Benefit/Pay-off Increases in community acceptance are expected to reduce the noise complaints and aid in reducing the restrictions currently being placed on rotorcraft operations. Enable design and flight operation methods that significantly reduce the community impacts of noise while simultaneously maintaining or improving high aerodynamic performance. Lateral distance [m] Moving Map 65 dba Annoyance Threshold Source Noise Intensity SEL X-position [m] Partners: FAA; U.S. Army ADD-AFDD Predicted SEL contours db Lateral distance [m] SEL-A Climb / Accel BVI Avoidance Guidance Descend / Decel X-position [m] 7 dba

8 Initial Design Optimization Demo APPROACH: Implement rotorcraft acoustic prediction method within the OpenMDAO framework. Demonstrate the method by optimizing a blade planform to simultaneously minimize low- and mid-frequency noise for a blade vortex interaction (descent) flight condition for an isolated rotor. ACCOMPLISHMENTS: Using CAMRADII, ANOPP2 and OpenMDAO, interfaces and methods were developed for user-defined rotorcraft configurations and flight conditions. Outboard blade chord, dihedral, sweep, radius, and twist were varied while maintaining key rotor similarity parameters. The acoustic objective function used an equally weighted combination of low- and mid-frequency acoustic pressure time history. The figures show the noise calculated at a key point under the rotor. The low- and midfrequency noise was reduced by 2.2dB and 13.0dB, respectively. Acoustic Pressure (Pa) Acoustic Pressure (Pa) Low Frequency Noise Baseline Optimized ROBIN-mod7 in 14- by 22-FST Rotor Rev Fraction Mid Frequency Noise Rotor Rev Fraction POC: Dr. Doug Boyd, LaRC 8

9 Fundamental Rotorcraft Acoustic Modeling from Experiments (FRAME) 7,500ft Sea Level 180 o 270 o 60 o 90 o 90 o 30 o 0 o 0 o 0 o Experimental Data Classified by Non- Dimensional Parameters (e.g. μ, λ, C T, M H ) Inverse Modeling of Individual Noise Sources POC: Dr. Eric Greenwood, LaRC 15,000ft Generalization to Other Operating Conditions using Non-Dimensional Models 9

10 Acoustic Impact of Flight Procedures Using FRAME-QS SEL, dba SEL, dba Steady Level Turn 175 ms computation time 80 second maneuver 0.25 second intervals 2500 observers 10 POC: Dr. Eric Greenwood, LaRC SEL, dba

11 Major NASA Experimental Facilities for Vertical Lift Acoustic Research Langley Research Center Mobile Acoustic Facility Exterior Effects Synthesis & Sim Lab 14- by 22-Foot Subsonic Tunnel Low Speed Aeroacoustic Tunnel Structural Acoustic Loads and Transmission Facility Ames Research Center National FullScale Aerodynamics Complex (NFAC) 11

12 Mobile Acoustic Facility Control Trailer with Satellite Wireless Acoustic Microphone Systems (WAMS) Microphone Inverted over Ground Board WAMS Deployed Aircraft Navigation and Tracking Precision Approach Path Indicator 12

13 Mobile Acoustic Facility Weather System Weather Balloon with temperature measured every 10 ft 1 of 5 weather sondes; measures temperature, pressure, humidity, wind speed and wind direction ZephIR 300 Portable LIDAR system; measures wind speed and direction at 13 user selectable heights up to 900 ft 13

14 Wireless Acoustic Microphone Systems 36 channels available Up to 50 mile range Data storage on compact flash card System health monitored in real time GPS card provides time code as well as position Simultaneous sampling on all channels (<8 µsec diff) Onboard embedded controller 80 khz max. sample rate 96 db dynamic range Battery operation w/solar power augmentation Weather data at each microphone location 14

15 Summary NASA has significant effort in developing advanced tools to predict vertical lift vehicle acoustics NASA capability in high quality experimental facilities ranges from small laboratories to the Mobile Acoustic Facility Future work - Community acceptance metric for multiple concepts - Optimization methods and design tools - Noise characteristics of small systems Outdoor UAV Acoustic Testing NASA RFI: Designing Next Generation VTOL UAS open now. Responses by May

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