Aeronautics

Scale-Resolving Methods for Jet Aeroacoustic Predictions

Image from jet engine simulation
Innovative supersonic noise design comparisons: This visualization captures a two-stream, internally mixed jet with an external plug (top) and an internal plug (bottom). The centerline plane at y=0 showcases temperature, and the colormap on the mixer and plug illustrates the y component of the velocity. While the top design displays a standard axisymmetric mixer, the bottom design introduces a noise-reducing lobed mixer, enhancing turbulent mixing and subsequently reducing far-field noise. Gerrit-Daniel Stich, NASA/Ames

NASA’s Commercial Supersonic Technology (CST) project has formulated a technical challenge to design a low-noise supersonic aircraft that meets Federal Aviation Administration (FAA) noise standards. While the sonic boom is the dominating source of sound during the supersonic phase of the flight, landing and takeoff (LTO) noise poses a high risk to the commercial supersonic market during subsonic flight over the U.S. mainland. Given that there are currently no noise rules for such aircraft during LTO, accurate noise-level predictions are essential in helping to shape future guidelines. For this reason, a team of research scientists at NASA’s Ames Research Center uses the Launch Ascent and Vehicle Analysis (LAVA) software to develop simulations to predict jet noise. Their goal is to reduce uncertainties and understand noise profiles of next-generation supersonic jets during takeoff and landing. These jets, different in design from modern airplanes, might produce unique sounds, especially with their anticipated low-bypass ratio engines. The resurgence of interest in supersonic travel makes this research vital. In support of NASA’s CST project, these high fidelity scale-resolving simulations help predict jet noise for NASA’s Low Boom Flight Demonstrator, leading to new insights for both future supersonic configurations and future FAA guidelines.

Quick Facts

Utilizing the NAS facility resources and services has been transformative for our research. These advanced computational tools have not only streamlined our processes but have truly accelerated our journey towards groundbreaking findings. With this approach, we are closer than ever to achieving certification by analysis.

Gerrit-Daniel Stich,
NASA Ames Research Center
  • Using supercomputers at the NASA Advanced Supercomputing (NAS) facility and the LAVA solver, the research team enhanced jet noise predictions by an order of magnitude. They efficiently used modern hardware, employed load balancing for scaling, and improved algorithms. This enabled the generation of a first-of-its-kind database for jet noise simulations of supersonic configurations.
  • Through enhancing wall-modeled large eddy simulation capabilities in the LAVA solver, they achieved a 65x reduction in simulation time, accurately predicted jet noise, spurred new research collaborations, and bolstered their jet noise database and understanding of jet noise prediction, advancing towards vehicle certification by analysis.
  • Their data contributes to helping shape and inform noise certification guidelines for future supersonic aircraft.
  • While great emphasis has been placed on making the numerical tools as efficient as possible, the manual mesh generation effort is still the biggest bottleneck to increase turnaround times for generating larger databases. The next step in this effort is to develop automated meshing tools to drastically reduce mesh generation time from weeks to minutes on contemporary workstations.

Researchers

  • Gerrit-Daniel Stich, NASA Ames Research Center
  • Jared Duensing, NASA Ames Research Center

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