Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study tests new muffler technology for auto industry

19.11.2003


Ohio A study of muffler technology at Ohio State University is giving automakers new options for designing quieter cars.

Engineers here have tested a promising new muffler design that utilizes glass fiber, and are developing the computational tools manufacturers will need to optimize the design.

The new design can often silence auto noise just as well as a typical muffler, but it can be lighter, less prone to corrosion, and help engines work more efficiently.



Ahmet Selamet, professor of mechanical engineering and head of the Flow, Engine, and Acoustics Research Laboratories at Ohio State’s Center for Automotive Research and Intelligent Transportation, gave an overview of his recent work November 19 at the American Society of Mechanical Engineers meeting in Washington, DC.

For more than a decade, Selamet and his colleagues have developed computer-based tools and specialized equipment for improving auto exhaust systems. The challenge, he said, is to control noise and exhaust emissions without blocking the flow of exhaust gases from the engine.

The ultimate silencing device is a potato in the tailpipe, Selamet said with a laugh. But of course engines need to breathe to work properly, so we have to be more creative.

Owens Corning recently asked Selamet to test and redesign a European muffler system that contained glass fiber stuffing. His task was to reduce the design complexity, reduce the weight of the system, and improve engine performance -- while at the same time maintaining or even improving overall exhaust noise levels.

Fiber-filled mufflers have been used in European and Japanese cars for years, Selamet explained, but not much elsewhere. In North America, most mufflers work by using metal chambers and baffles to slow the flow of air or redirect it.

But chambers and baffles can restrict the flow of the exhaust gases, increasing what is known as back pressure. When that happens, some of an engines work is wasted pushing the burned gases through the exhaust system, instead of pushing the car forward. With a simpler interior design, a fiber-filled muffler could cause less back pressure and make engines more efficient.

Historically, though, the North American auto industry has been skeptical about using filling in mufflers, and rightly so, Selamet said. Early European designs used basalt wool, which is packed in short fibers. Studies have shown that over time, these short fibers break up and blow out in the exhaust stream.

Then the car gets louder, Selamet said.

Continuous glass fiber could offer a better alternative to wool, he said, because the fiber strands are too long and intertwined to be blown out of the muffler. According to Owens Corning, a gumball-sized glass marble that is spun into a strand of continuous fiber for exhaust applications can measure 18 miles long, with a diameter one quarter that of a human hair.

Selamet also said that glass fiber can better withstand the high temperatures produced in modern exhaust systems, and potentially even insulate the car from that heat.

Since automakers such as Volvo are using glass fiber in mufflers sold in Europe, Selamet had an opportunity to test the design. Owens Corning supplied him with new and used Volvo mufflers, as well as loose fiber samples. The used mufflers came from cars that had been driven 100,000 miles.

In tests, Selamet and his colleagues found that the fiber reduced engine noise substantially. For example, at the mid-range frequency of 1500 Hertz, the new design reduced the noise by 40 decibels. Thats significantly higher than the typical muffler rating of 30 decibels or lower.

The mufflers used for 100,000 miles performed just as well as the new.

The Ohio State engineers developed a computerized tool that manufacturers can use in optimizing the design of a fiber-filled mufflers for different car models.

A major parts maker has also expressed interest in using the fibers in an automotive intake system, where, as Selamet pointed out, automakers have a big opportunity to quiet engine noise.

One of the most powerful noise-reducers in the intake system of a car is the air cleaner box, he said, referring to the housing that contains filter to clean debris from the outside air before feeding it to the engine.


#

Contact: Ahmet Selamet, (614) 292-4143; Selamet.1@osu.edu
Written by Pam Frost Gorder, (614) 292-9475; Gorder.1@osu.edu

Pam Frost Gorder | Ohio State University
Further information:
http://researchnews.osu.edu/archive/fibrmufl.htm

More articles from Transportation and Logistics:

nachricht Study sets new distance record for medical drone transport
13.09.2017 | Johns Hopkins Medicine

nachricht Researchers 'count cars' -- literally -- to find a better way to control heavy traffic
10.08.2017 | Florida Atlantic University

All articles from Transportation and Logistics >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>