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Destination Tomorrow - DT9 - Quiet Aircraft Technology
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NASA Destination Tomorrow Segment describing how NASA scientists are trying to reduce noise created by aircraft. The segment describes some of the equipment and technology in use in laboratories to reduce noise levels.
The United States aviation industry is a significant contributor to the nation's economy,
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boasting annual sales in excess of $36 billion and providing nearly 1 million jobs.
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However, with all of these benefits, one major drawback continues to be aircraft noise.
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In an effort to help alleviate excessive noise, NASA has developed the Quiet Aircraft Technology Program.
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This program is finding new and innovative ways to reduce noise created by aircraft.
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Jennifer Pulley finds out more.
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Noise generated by aircraft is already a major issue in airport neighbor communities.
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As airports expand to increase productivity and capacity, the noise issue will become even more critical.
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Noisy aircraft not only affect the people in communities surrounding the airport,
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but also the crew and passengers inside the planes.
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In an attempt to solve many of the noise issues associated with aircraft,
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NASA has embarked on an intriguing new mission to quiet our skies,
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called the Quiet Aircraft Technology Program, or QAT.
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This program will develop technologies to reduce aircraft noise by 50% in five years
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and begin working on the technologies to reduce aircraft noise by 75% in the next 20 years.
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I spoke with Andy Powell at NASA Langley Research Center to find out more.
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On takeoff, most of the noise that you hear is due to the engine,
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both the fan in the front of the engine and the jet exhaust noise out of the rear engine.
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And what most people don't know is that on landing,
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a lot of the noise that you hear is actually due to the airframe passing through the air itself.
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This is because on landing, the engine power is cut back
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and a lot of parts of the aircraft are extended into the airflow and create turbulence.
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Now the major sources of this airframe noise is the landing gear,
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the flaps on the trailing edges, and slats on the leading edges of the wings.
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In a recent government survey, noise was listed as the greatest environmental concern at airports.
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It is estimated that in the last 20 years,
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approximately $4 billion has been spent on or around airports to reduce noise pollution.
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This includes adding sound insulation to homes and schools in close proximity to an airport.
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Unfortunately, these techniques only help if you are inside an insulated building.
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Researchers at NASA realize that in order to fix the noise problem,
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they must first start at the source, the planes themselves.
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By designing and testing low-noise-producing aircraft parts and structures,
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NASA researchers are developing the technologies to reduce aircraft noise by half in five years
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and by as much as three-fourths by the year 2020.
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So what are some of the things you're working on here at NASA to make aircraft quieter?
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First, we do studies to look at the sources of noise to try to determine which are the dominant sources
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so that we can know which sources can work on the hardest.
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Then we do other studies to try to determine the physical phenomena that are creating the noises
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and what we can do to reduce the levels.
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And then we go out and test concepts either in wind tunnels or in the laboratory
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and in some cases in actual flight tests to validate those concepts.
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One of the things that we're doing is to look at advanced fairings to put around the landing gear
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to smooth the flow around the landing gear so that you don't have as much turbulence
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and therefore reduce the noise.
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We're also looking at other fairings that we can put on the slats
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so that you don't have side edges to create noise.
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We're also modifying the fan blades so that they're actually quieter from the design of the fan blades.
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If you can smooth the airflow around these parts,
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then reducing that turbulence will reduce the noise considerably.
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Andy, what about the exhaust noise coming out of an aircraft?
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Okay, well, one of the things that we did was look at what we call chevron nozzles.
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These are actually scallops in the back of the exhaust pipes, essentially, of the aircraft.
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And as hot exhaust gases come out of an aircraft engine,
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then they mix with the surrounding air and this turbulence, when they're mixing,
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creates a lot of the noise that you hear.
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Now, by putting these chevrons along the edges,
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we're changing the shape of the turbulence so that you raise it to a higher frequency,
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which then is absorbed more by the atmosphere than the low-frequency, normal jet noise.
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The chevron nozzles have actually been test flown full-scale on a major aircraft,
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and we expect that these will actually be coming in on the production of aircraft engines in the very near future.
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We've talked about engine and airframe noise.
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Are there other ways to reduce noise without major design alterations to an airplane?
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Yes, we're actually looking at new ways to fly the aircraft around the airport
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so that they've minimized the exposure of people to the aircraft noise.
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For instance, around a lot of airports, they fly noise abatement procedures
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to get the flights away from schools and houses.
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But in some situations, if the wind is blowing,
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these flight paths may not be the optimum flight path
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because of the effects that wind has on the sound propagation.
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So we're doing studies on improving the prediction of sound propagation
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to include the effects of wind, weather,
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and this way we hope that we will be able to reduce the noise and have the planes fly optimal paths.
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And finally, what are your overall hopes for the QAT program?
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Well, one of the three elements in NASA's vision is to improve life here on planet Earth.
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And we think through this Quiet Aircraft Technology Program,
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we're making a major contribution to improving the life for people
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and the environment around airports, both in the nation and throughout the world.
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Ultimately, NASA would like to reduce airport noise
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so that no one outside the airport boundary is adversely affected.
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- Niveles educativos:
- ▼ Mostrar / ocultar niveles
- Nivel Intermedio
- Autor/es:
- NASA LaRC Office of Education
- Subido por:
- EducaMadrid
- Licencia:
- Reconocimiento - No comercial - Sin obra derivada
- Visualizaciones:
- 502
- Fecha:
- 28 de mayo de 2007 - 17:04
- Visibilidad:
- Público
- Enlace Relacionado:
- NASAs center for distance learning
- Duración:
- 05′ 35″
- Relación de aspecto:
- 4:3 Hasta 2009 fue el estándar utilizado en la televisión PAL; muchas pantallas de ordenador y televisores usan este estándar, erróneamente llamado cuadrado, cuando en la realidad es rectangular o wide.
- Resolución:
- 480x360 píxeles
- Tamaño:
- 32.47 MBytes
