Systems Analysis of Community Noise Impacts of Advanced Flight Procedures for Conventional and Hybrid Electric Aircraft
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Systems Analysis of Community Noise Impacts of Advanced Flight Procedures for Conventional and Hybrid Electric Aircraft This report is based on the PhD Thesis of Jacqueline L. Thomas submitted to the Department of Aeronautics and Astronautics in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology Jacqueline Thomas Committee: Dr. R. John Hansman Dr. Mark Drela Dr. Robert H. Liebeck Report No. ICAT-2020-06 June 2020 MIT International Center for Air Transportation (ICAT) Department of Aeronautics & Astronautics Massachusetts Institute of Technology Cambridge, MA 02139 USA 1 Systems Analysis of Community Noise Impacts of Advanced Flight Procedures for Conventional and Hybrid Electric Aircraft by Jacqueline Thomas Abstract Recent changes to aircraft approach and departure procedures enabled by more precise navigation technologies have created noise concentration problems for communities beneath flight tracks. There may be opportunities to reduce community noise impacts under these concentrated flight tracks through advanced operational approach and departure procedures and advanced aircraft technologies. A modeling method to assess their impacts must consider the contributions of aircraft engine and airframe noise sources as they vary with the position, thrust, velocity, and configuration of the aircraft during the flight procedure. The objective is to develop an analysis method to design, model, and assess the community noise reduction possibilities of advanced operational flight procedures performed by conventional aircraft and advanced procedures enabled by future aircraft concepts. An integrated analysis framework is developed that combines flight dynamics and noise source models to determine the community noise impacts of aircraft performing advanced operational approach and departure procedures. Aircraft noise due to the airframe and engine is modeled using an aircraft source noise module as each noise component varies throughout the flight procedure and requires internal engine performance states, the flight profile, and aircraft geometry. An aircraft performance module is used to obtain engine internal performance states and aircraft flight performance given the aircraft technology level. A force- balance-kinematics flight profile generation module converts the flight procedure definition into altitude, position, velocity, configuration, and thrust profiles given flight performance on a segment-by-segment basis. The system generates single-event surface noise grids that are combined with population census data to estimate population noise exposure for a given aircraft technology level and procedure. The framework was demonstrated for both advanced approach and departure procedures and advanced aircraft technologies. The advanced procedure concepts include modified speed and thrust departures as well as continuous descent, steep, and delayed deceleration approaches for conventional aircraft. The ability to model advanced aircraft technologies was demonstrated in the evaluation of using windmilling drag by hybrid electric aircraft on approach to allow the performance of steep and delayed deceleration approaches for noise reduction beyond the performance capability of standard gas-turbine aircraft. Acknowledgments This work is funded by the US Federal Aviation Administration (FAA) Office of Environment and Energy as a part of ASCENT Project 23 and Project 44. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author and do not necessarily reflect the views of the FAA or other ASCENT Sponsors. The author would like to acknowledge the support of Chris Dorbian, Joseph DiPardo, and Bill He of the FAA Office of Environment and Energy as well as the Massachusetts Port Authority andHMMH. The author would also like to acknowledge the support and flight test collaboration with Boeing, including the help of Gail Barker and Terry Christenson, as well as with the FAA Technical Center, including Ian Levitt and Andrew Cheng. Finally, the author would like to acknowledge the technical support of NASA. 4 Contents 1 Introduction and Objectives 16 1.1 Problem Introduction . 16 1.1.1 The Community Noise Problem Caused by Approaching and Departing Aircraft . 16 1.2 Noise Reduction Opportunities of Conventional Aircraft Performing Advanced Operational Approach and Departure Procedures . 19 1.3 Reduction Opportunities of Future Aircraft, Including Hybrid Electric Aircraft with Windmilling Drag . 20 1.4 Full Flight Procedure Analysis Requires System Approach . 21 1.5 Thesis Objective . 24 1.6 Thesis Outline . 25 2 Literature Review 26 2.1 Primary Aircraft Noise Sources . 26 2.2 Aircraft Noise Improvements Since 1969 and Present Considerations . 30 2.3 Existing Aircraft Noise Models . 34 2.4 Noise Abatement with Advanced Operational Flight Procedures . 38 2.4.1 Lateral Profile Adjustments for Noise Abatement . 38 2.4.2 Vertical Flight Profile Adjustments for Noise Abatement . 40 2.5 Noise Reduction Opportunities of Advanced Configurations . 46 2.5.1 Quiet Drag Concepts . 46 2.5.2 Background on Hybrid Electric Aircraft . 51 3 Framework for Analyzing Performance and Noise of Advanced Operational Flight Procedures of Conventional Aircraft 58 3.1 Aircraft Performance Model . 60 3.1.1 Flight Performance from BADA 4 . 62 3.1.2 Internal Engine Performance Maps and Geometry from TASOPT . 62 3.1.3 Geometry Outputs from External Sources . 66 3.2 Flight Profile Generation Module . 67 3.3 Component-Based Aircraft Noise Module . 73 3.3.1 Turbofan Engine Source Noise Modeling . 75 3.3.2 Airframe Source Noise Modeling . 78 3.3.3 Noise Propagation and Noise Metric Modeling . 79 3.4 Noise Impact Metric Module . 80 5 3.5 Validation of Noise Results of Turbofan Aircraft with Existing Certification Data........................................ 82 4 Advanced Operational Flight Procedures of Conventional Aircraft—Evaluation of the Impact of Flight Path Angle and Speed on Community Noise 87 4.1 Impact of Aircraft Flight Path Angle and Speed on Aircraft Source Noise . 88 4.1.1 Impact of Flight Path Angle and Speed on Engine Noise . 88 4.1.2 Impact of Flight Path Angle and Speed on Airframe Noise . 89 4.2 Effect of Aircraft Flight Path Angle and Speed on Departure . 89 4.2.1 Options to Change Aircraft Flight Path Angle and Speed on Departure 89 4.2.2 Changing Location of the Start of Acceleration and Flap Retraction . 90 4.2.3 Reduced Climb Speed . 99 4.2.4 Changing the Climb Angle . 104 4.2.5 Operational Implications of Altered Climb Angle Departures . 106 4.3 Effect of Aircraft Flight Path Angle and Speed on Approach . 107 4.3.1 Options to Change Aircraft Flight Path Angle and Speed on Approach 107 4.3.2 Continuous Descent Approaches . 110 4.3.3 Delayed Deceleration Approaches . 116 4.3.4 Operational Implications of Continuous Descent and Delayed Deceleration Approaches . 124 4.4 ecoDemonstrator 2019 Flight Trials of Delayed Deceleration Approaches . 126 4.4.1 Proposed Delayed Deceleration Approach Procedure with 3.77∘ Final Descent . 126 4.4.2 ecoDemonstrator Flight Trials and Comparisons to Modeled Noise Results . 133 4.5 Chapter 4 Conclusion . 143 5 Framework for Analyzing Performance and Noise of Windmilling Drag and Hybrid Electric Aircraft 145 5.1 Aircraft Performance Model to Include Electrified Engines . 147 5.1.1 Hybrid-Electric Aircraft Performance Model . 147 5.1.2 Windmilling Engine Drag Model . 153 5.2 Component-Based Aircraft Noise Module with Windmilling Fan Noise . 156 5.2.1 Windmilling Fan Noise Modeling . 157 5.3 Validation of Windmilling Engine Drag Coefficients . 166 5.4 Validation of Fan Noise Model Adapted for Windmilling . 169 5.4.1 Broadband Fan Noise Model Compared to ANOPP Fan Noise Module at Standard Approach Operating Conditions . 169 5.4.2 Fan Noise Model Compared to Existing Data at Windmilling Conditions171 5.4.3 Windmilling Fan Tone Noise . 173 6 Case Studies of Advanced Operational Flight Procedures Performed by Hybrid Electric Aircraft with Windmilling Engine Drag 175 6.1 Hybrid Electric Engine Retrofit Sizing Results . 176 6 6.2 Windmilling Engine Noise versus Drag of Retrofit Hybrid Electric Aircraft . 178 6.3 Case Study 1: Performance and Noise Analysis of Steeper Approaches with Windmilling Drag . 181 6.3.1 Steeper Approach Profile with Windmilling Drag . 182 6.3.2 Single Event Flyover Noise Modeling of the Baseline and Steeper Approaches with Windmilling Drag . 183 6.4 Case Study 2: Performance and Noise Analysis of Delayed Deceleration Approaches with Windmilling Drag . 190 6.4.1 Delayed Deceleration Approach Profile with Windmilling Drag . 190 6.4.2 Single Event Flyover Noise Modeling of Baseline and Delayed Deceleration Approaches with Windmilling Drag . 192 6.5 Case Study 3: Performance and Noise Analysis of Combined Delayed Deceleration Steeper Approaches with Windmilling Drag . 199 6.5.1 Combined Delayed Deceleration Steeper Approach Profile with Windmilling Drag . 199 6.5.2 Single Event Flyover Noise Modeling of Baseline and Combined Delayed Deceleration Steeper Approaches with Windmilling Drag . 201 6.6 Chapter 6 Conclusion . 205 7 Conclusion 207 7.1 Thesis Framework and Analysis Results Summary . 207 7.2 Primary Contributions . 211 7.3 Discussion and Future Work . 211 References 213 7 List of Figures 1-1 Comparison of Conventional, RNAV, and RNP Navigation, Figure from FAA . 17 1-2 Arrival and Departure Flight Paths and Noise Complaints at BOS in 2010 and 2017, Figures from [3] . 18 1-3 Analysis