Turning Down the Noise
04.2.11
NASA scientists and engineers are working toward a day when living near an airport will no longer mean being disturbed by the whine of jets overhead.
Have you ever had the experience of finding the perfect house or apartment, only to be deterred by the fact that it is on an airport flight path? For many Americans, the answer to that question is "yes." That is why NASA scientists and engineers are working toward a day when living near an airport will no longer mean being disturbed by the whine of jets overhead.
Although aircraft engine noise has been substantially reduced in recent years, this has revealed another, less obvious source of landing and takeoff noise: the airframe. High-lift devices on the wing and aircraft landing gear are currently the largest airframe noise sources for civil transport. As part of NASA's noise reduction effort, carried out under the Environmentally Responsible Aviation and Subsonic Fixed Wing Projects, researchers are partnering with Gulfstream Aerospace Corp. to study the nose landing gear of a G550 aircraft using NASA's most powerful production supercomputer.
Large Calculations Require Supercomputers
"Computational studies of landing gear are beginning to reveal some of the intricacies of the flow that may lead to significant noise reduction techniques," said Mehdi Khorrami, lead project investigator at NASA Langley Research Center, Hampton, Va. "In order to adequately simulate the complex flow around landing gear requires very large calculations that can only be run on supercomputers."
Using NASA Langley's FUN3D (Fully-Unstructured Navier-Stokes) computational fluid dynamics (CFD) code, Khorrami with colleagues Veer Vatsa and David Lockard are simulating the G550 landing gear on the 84,992-core Pleiades supercomputer at the NASA Advanced Supercomputing (NAS) Divison of NASA Ames Research Center in California.
Their calculations, which were run on 1,200 cores simultaneously, use 1.7 million processor-hours for a single simulation at the finest resolution. Furthermore, storing the large simulation solutions requires many terabytes of disk space. The combined capabilities of Pleiades, mass data storage, and post-processing expertise available at the NAS facility have enabled the resolution and visualization of the prominent flow features over a broad range of spatial-temporal scales.
Simulations for Future Aircraft
Khorrami, Vatsa, and Lockard are using these high-fidelity numerical simulations to improve the current understanding of aircraft nose landing gear noise in several important ways, including: determining the categories of noise being produced, pinpointing the locations of noise sources, and providing guidance on effective noise-reduction technologies.
These NASA simulations will be integrated with experimental flight-test and wind tunnel data to guide the design of quieter, more efficient airframe components, which will become part of a new generation of ultra-quiet, low-emission, subsonic aircraft designs—leading to reduced fuel consumption and quieter skies over our neighborhoods.
— Jill Dunbar and John Hardman
Contact
Mehdi Khorrami
NASA Langley Research Center
mehdi.r.khorrami@nasa.gov
David Lockard
NASA Langley Research Center
d.p.lockard@nasa.gov
