Study of Noise-Certification Standards for Aircraft Engines. Volume 2. Procedures for Measuring Far Field Sound Pressure Levels Around an Outdoor Jet-Engine Test Stand


Book Description

This study, reported in three volumes, had the purpose of considering the feasibility of establishing an FAA requirement for a manufacturer of aircraft engines to demonstrate compliance with an engine noise-level standard in order to obtain an engine-noise type certificate. The objective of engine-noise type certification would be to supplement the aircraft-noise type certification requirements in Part 36 of the Federal Aviation Regulations. The scope of the study was limited to aircraft turbofan engines. Volume 2 describes the general characterisitics of 16 outdoor engine test stands used by 11 organizations for measurements of engine noise levels. Instruments and microphone installations are also described. Recommendations are presented for test procedures to measure farfield sound pressure levels around a turbofan engine mounted on an outdoor test stand. After adjusting the measured data to common reference conditions, the test results should be suitable for demonstrating compliance with the requirements for a static-engine noise type certificate.







Study of Noise-Certification Standards for Aircraft Engines. Volume 3. Selection and Evaluation of Engine-Noise-Certification Concept


Book Description

The purpose of this 3-volume study was to consider the feasibility of establishing an FAA requirement for a manufacturer of aircraft engines to demonstrate compliance with an engine noise-level standard in order to obtain an engine-noise type certificate. The objective of engine-noise type certification (if feasible on the basis of economic reasonableness, technological practicality, and appropriateness to the type design) would be to supplement the aircraft-noise type certification requirements in Part 36 of the Federal Aviation Regulations. This study was limited to aircraft jet engines. Volume 3 describes the selection of a concept for the noise-evaluation quantity, namely the A-frequency-weighted sound power made nondimensional by a power-like quantity equal to the product of total net static thrust and the speed of sound in the ambient air. The recommended independent variable is total net static thrust made nondimensional by the product of total mass flow rate and the speed of sound in the ambient air. Farfield 1/3-octave-band sound pressure levels, measured around production and experimental versions of aircraft turbojet and turbofan engines, were used to test the utility and applicability of the recommended noise-evaluation quantity. Engines ranged in rated static thrust from 11 kN to 222 kN (2500 lb to 50,000 lb). For certification purposes, a certifying authority would select appropriate limits on the magnitude of the noise-evaluation quantity applicable to thrust settings representative of takeoff and landing approach.




Study of Noise-Certification Standards for Aircraft Engines. Volume 1. Noise-Control Technology for Turbofan Engines


Book Description

This study, reported in three volume, had the purpose of considering the feasibility of establishing an FAA requirement for a manufacturer of aircraft engines to demonstrate compliance with an engine noise-level standard in order to obtain an engine noise type certificate. The objective of engine-noise type certification (if feasible on the basis of economic reasonableness, technological practicality, and appropriateness to the type design) would be to supplement the aircraft-noise type certification requirements in Part 36 of the Federal Aviation Regulations. The scope of the study was limited to aircraft turbofan engines. Volume 1 identifies sources of noise produced by aircraft turbofan engines, proposes a working definition of an engine's envelope within which an engine manufacturer may incorporate noise control design features, and evaluates applications of noise-control designs to 22 experimental and production versions of turbofan engines developed over a period from late 1950s to the mid 1970s and ranging in nominal take-off-rated thrust from 7.2 to 236 kN (1600 to 53 000 lb). A description is included of the general procedure for selecting appropriate noise-control designs applicable within the engine envelope for various sources of engine noise.










Aircraft Engine Noise Research


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Aviation Noise


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For Greener Skies


Book Description

Each new generation of commercial aircraft produces less noise and fewer emissions per passenger-kilometer (or ton-kilometer of cargo) than the previous generation. However, the demand for air transportation services grows so quickly that total aircraft noise and emissions continue to increase. Meanwhile, federal, state, and local noise and air quality standards in the United States and overseas have become more stringent. It is becoming more difficult to reconcile public demand for inexpensive, easily accessible air transportation services with concurrent desires to reduce noise, improve local air quality, and protect the global environment against climate change and depletion of stratospheric ozone. This situation calls for federal leadership and strong action from industry and government. U.S. government, industry, and universities conduct research and develop technology that could help reduce aircraft noise and emissions-but only if the results are used to improve operational systems or standards. For example, the (now terminated) Advanced Subsonic Technology Program of the National Aeronautics and Space Administration (NASA) generally brought new technology only to the point where a system, subsystem model, or prototype was demonstrated or could be validated in a relevant environment. Completing the maturation process-by fielding affordable, proven, commercially available systems for installation on new or modified aircraft-was left to industry and generally took place only if industry had an economic or regulatory incentive to make the necessary investment. In response to this situation, the Federal Aviation Administration, NASA, and the Environmental Protection Agency, asked the Aeronautics and Space Engineering Board of the National Research Council to recommend research strategies and approaches that would further efforts to mitigate the environmental effects (i.e., noise and emissions) of aviation. The statement of task required the Committee on Aeronautics Research and Technology for Environmental Compatibility to assess whether existing research policies and programs are likely to foster the technological improvements needed to ensure that environmental constraints do not become a significant barrier to growth of the aviation sector.