ALCF Simulations Aim to Reduce Jet Engine Noise

September 21, 2017

CHICAGO, Ill., Sept. 21, 2017 — Humans make a lot of noise. The riffs of heavy metal bands like Metallica and Kiss have soared to levels in the 130-decibel range, levels sure to lead to auditory damage.

But try as they might, bands just can’t compete with the decibel ranges produced by jet engines. They are, said Joe Nichols, among the loudest sources of human-made noise that exist.

An assistant professor of Aerospace Engineering and Mechanics at the University of Minnesota, Nichols is fascinated by sound and its ability to find order in chaos – and by applying that understanding to the development of new technologies that can reduce noise in aircraft.

“His project leverages computational data with what he calls input-output analysis, which reveals the origins of jet noise that are otherwise hidden in direct run-of-the-mill forward simulations, or even experiments.” – Ramesh Balakrishnan, Argonne computational scientist

Nichols is working with the Argonne Leadership Computing Facility (ALCF), a U.S. Department of Energy (DOE) Office of Science User Facility within the DOE’s Argonne National Laboratory, to create high-fidelity computer simulations to determine how jet turbulence produces noise. The results may lead to novel engineering designs that reduce noise over commercial flight paths and on aircraft carrier decks.

“Noise tells you something about the fundamental nature of turbulence, because noise reveals order that is otherwise hidden in complex, highly nonlinear, chaotic phenomena,” he said.

That is why jet noise presents both a challenging and a beautiful problem for Nichols.

Taming the roar of the engine

Jet engines produce noise in different ways, but mainly it comes from the high-speed exhaust stream that leaves the nozzle at the rear of the engine. And planes are loudest when they move slowly, such as at takeoff or at landing. As the exhaust stream meets relatively still air, it creates tremendous shear that quickly becomes unstable. The turbulence produced from this instability becomes the roar of the engine.

Aeronautic engineers incorporate chevrons, broken eggshell-shaped patterns, into exhaust nozzle designs to change the shape of the jet as it leaves the engine. The idea is to reduce the noise by changing the pattern of the turbulence. But much of the design work remains a guessing game.

Working with ALCF computational scientist Ramesh Balakrishnan and Argonne’s supercomputer Mira, Nichols and his team are applying computational fluid dynamics to remove some of that guesswork. They start by conducting high-fidelity large eddy simulations that accurately capture the physics of the turbulence that is making the noise.

From those simulations they extract reduced-order, or more concise, models that explain what part of the turbulence actually makes the sound. In addition to improving scientific understanding of jet noise, these reduced-order models also provide a fast, yet accurate, means for engineers to evaluate new designs.

Simulating complex geometries like jet turbulence requires the use of an unstructured mesh — a non-uniform 3-D grid — to represent the dynamics involved. In this case, one simulation could have 500 million grid points. Multiply that by five to account for pressure, density and three components of velocity to describe the flow at every grid point. That equates to billions of degrees of freedom, or the number of variables Mira uses to simulate jet noise.

“But what if inside the jet turbulence there is a skeleton of coherent flow structures that we can describe with just 50 degrees of freedom,” suggested Nichols. “Which aspects are most important to the jet noise production? How do the flow structures interact with each other? How closely can the skeleton model represent the high-fidelity simulation?”

This work, published last year in the journal Physics of Fluids, could help engineers more precisely direct the modeling of jet engine nozzle geometries by determining, for instance, the ideal number and length of chevrons.

“What distinguishes Joe’s work from those of the other computational fluid dynamics projects at ALCF is that it involves the development of a method that could mature into becoming a design tool for aero-acoustics,” said ALCF’s Balakrishnan. “His project leverages computational data with what he calls input-output analysis, which reveals the origins of jet noise that are otherwise hidden in direct run-of-the-mill forward simulations, or even experiments.”

Simulating waves of aviation

One of the leading ways to predict the instability waves that create sound inside of turbulence is through methods based on a type of computational tool called parabolized stability equations. But while they’re good at predicting supersonic sound sources, they have a hard time predicting all the components of subsonic jet noise, especially in the sideline direction, or perpendicular to the exhaust stream.

The University of Minnesota team developed a new method based on input-output analysis that can predict both the downstream noise and the sideline noise. While it was thought that the sideline noise was random, the input-output modes show coherent structure in the jet that is connected to the sideline noise, such that it can be predicted and controlled.

Nichols also uses a variation on the input-output analysis to study noise produced by impingement, where a jet blast is directed at a flat surface, such as aircraft taking off from or hovering over an aircraft carrier deck.

Like decibel-breaking guitar licks, impingement produces a feedback loop when the turbulence hits a flat surface and accelerates outward. As the noise loops back towards the jet nozzle, new turbulence is triggered, creating extremely large tones that can reach into the 170-decibel range and do structural damage to the aircraft in question.

Nichols and his team are applying computational fluid dynamics to reduce the noise by changing the pattern of the turbulence. With Nichols are Anubhav Dwivedi (left) and Jinah Jeun (right), graduate students in Aerospace Engineering and Mechanics at the University of Minnesota. (Image courtesy of University of Minnesota.)

The team turned to Mira to conduct a high-fidelity simulation of an impinging jet without any modifications, and then measured the noise it produced. When compared to ongoing experiments, they predicted those same tones very accurately. A reduced-order model of the simulations helped Nichols more precisely predict how to change the jet configuration to eliminate feedback tones. Another simulation of the modified jet showed that the tones were almost completely gone.

“The simulations play a crucial role because they let us see spatio-temporally resolved fluid motions that would be impossible to measure experimentally, especially if you’re talking about a hot exhaust moving at Mach 1.5,” noted Nichols.

This research, says Balakrishnan, is still a work in progress, but the results are encouraging. While it still needs some refinement, it holds the promise of becoming a design tool that jet engine manufacturers may one day use to help quiet the skies.

For electric guitar makers Fender and Gibson, on the other hand, perhaps not so much.

Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.

The U.S. Department of Energy’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit the Office of Science website.


Source: John Spizzirri, ANL

Subscribe to HPCwire's Weekly Update!

Be the most informed person in the room! Stay ahead of the tech trends with industy updates delivered to you every week!

InfiniBand Still Tops in Supercomputing

July 19, 2018

In the competitive global HPC landscape, system and processor vendors, nations and end user sites certainly get a lot of attention--deservedly so--but more than ever, the network plays a crucial role. While fast, perform Read more…

By Tiffany Trader

HPC for Life: Genomics, Brain Research, and Beyond

July 19, 2018

During the past few decades, the life sciences have witnessed one landmark discovery after another with the aid of HPC, paving the way toward a new era of personalized treatments based on an individual’s genetic makeup Read more…

By Warren Froelich

WCRP’s New Strategic Plan for Climate Research Highlights the Importance of HPC

July 19, 2018

As climate modeling increasingly leverages exascale computing and researchers warn of an impending computing gap in climate research, the World Climate Research Programme (WCRP) is developing its new Strategic Plan – and high-performance computing is slated to play a critical role. Read more…

By Oliver Peckham

HPE Extreme Performance Solutions

Introducing the First Integrated System Management Software for HPC Clusters from HPE

How do you manage your complex, growing cluster environments? Answer that big challenge with the new HPC cluster management solution: HPE Performance Cluster Manager. Read more…

IBM Accelerated Insights

Are Your Software Licenses Impeding Your Productivity?

In my previous article, Improving chip yield rates with cognitive manufacturing, I highlighted the costs associated with semiconductor manufacturing, and how cognitive methods can yield benefits in both design and manufacture.  Read more…

U.S. Exascale Computing Project Releases Software Technology Progress Report

July 19, 2018

As is often noted the race to exascale computing isn’t just about hardware. This week the U.S. Exascale Computing Project (ECP) released its latest Software Technology (ST) Capability Assessment Report detailing progress so far. Read more…

By John Russell

InfiniBand Still Tops in Supercomputing

July 19, 2018

In the competitive global HPC landscape, system and processor vendors, nations and end user sites certainly get a lot of attention--deservedly so--but more than Read more…

By Tiffany Trader

HPC for Life: Genomics, Brain Research, and Beyond

July 19, 2018

During the past few decades, the life sciences have witnessed one landmark discovery after another with the aid of HPC, paving the way toward a new era of perso Read more…

By Warren Froelich

D-Wave Breaks New Ground in Quantum Simulation

July 16, 2018

Last Friday D-Wave scientists and colleagues published work in Science which they say represents the first fulfillment of Richard Feynman’s 1982 notion that Read more…

By John Russell

AI Thought Leaders on Capitol Hill

July 14, 2018

On Thursday, July 12, the House Committee on Science, Space, and Technology heard from four academic and industry leaders – representatives from Berkeley Lab, Argonne Lab, GE Global Research and Carnegie Mellon University – on the opportunities springing from the intersection of machine learning and advanced-scale computing. Read more…

By Tiffany Trader

HPC Serves as a ‘Rosetta Stone’ for the Information Age

July 12, 2018

In an age defined and transformed by its data, several large-scale scientific instruments around the globe might be viewed as a ‘mother lode’ of precious data. With names seemingly created for a ‘techno-speak’ glossary, these interferometers, cyclotrons, sequencers, solenoids, satellite altimeters, and cryo-electron microscopes are churning out data in previously unthinkable and seemingly incomprehensible quantities -- billions, trillions and quadrillions of bits and bytes of electro-magnetic code. Read more…

By Warren Froelich

Tsinghua Powers Through ISC18 Field

July 10, 2018

Tsinghua University topped all other competitors at the ISC18 Student Cluster Competition with an overall score of 88.43 out of 100. This gives Tsinghua their s Read more…

By Dan Olds

HPE, EPFL Launch Blue Brain 5 Supercomputer

July 10, 2018

HPE and the Ecole Polytechnique Federale de Lausannne (EPFL) Blue Brain Project yesterday introduced Blue Brain 5, a new supercomputer built by HPE, which displ Read more…

By John Russell

Pumping New Life into HPC Clusters, the Case for Liquid Cooling

July 10, 2018

High Performance Computing (HPC) faces some daunting challenges in the coming years as traditional, industry-standard systems push the boundaries of data center Read more…

By Scott Tease

Leading Solution Providers

SC17 Booth Video Tours Playlist

Altair @ SC17

Altair

AMD @ SC17

AMD

ASRock Rack @ SC17

ASRock Rack

CEJN @ SC17

CEJN

DDN Storage @ SC17

DDN Storage

Huawei @ SC17

Huawei

IBM @ SC17

IBM

IBM Power Systems @ SC17

IBM Power Systems

Intel @ SC17

Intel

Lenovo @ SC17

Lenovo

Mellanox Technologies @ SC17

Mellanox Technologies

Microsoft @ SC17

Microsoft

Penguin Computing @ SC17

Penguin Computing

Pure Storage @ SC17

Pure Storage

Supericro @ SC17

Supericro

Tyan @ SC17

Tyan

Univa @ SC17

Univa

  • arrow
  • Click Here for More Headlines
  • arrow
Do NOT follow this link or you will be banned from the site!
Share This