Featured Research

from universities, journals, and other organizations

University Of Arkansas Physicists Develop Laser Probe For Multi-Parameter Measurements In Combustion

Date:
June 25, 2002
Source:
University Of Arkansas
Summary:
Fire shaped the history of humans and today it fuels power plants and car engines, but researchers have yet to understand the inner workings of combustion. Physicists at the University of Arkansas have created an optical probe that combustion scientists can use to measure many different aspects of combustion's components simultaneously.

FAYETTEVILLE, Ark. -- Fire shaped the history of humans and today it fuels power plants and car engines, but researchers have yet to understand the inner workings of combustion. Physicists at the University of Arkansas have created an optical probe that combustion scientists can use to measure many different aspects of combustion's components simultaneously.

Related Articles


Rajendra Gupta, professor of physics, will present his findings at the International Conference on Photoacoustic and Photothermal Phenomena at the University of Toronto in Canada.

"If you could understand combustion, you could presumably create engines that are more efficient and less polluting," Gupta said.

Even when methane, the simplest of carbon fuels, burns, it produces small quantities of molecular species--radicals that play an important role in combustion chemistry--before the reactants end up as carbon dioxide and water. These highly reactive species range in concentration from parts per thousand to parts per million.

Researchers have developed theoretical models that describe these species, and have measured them experimentally. However, the currently used measurement techniques have limitations: They produce relative measurements of molecular concentrations, not absolute concentrations. And they only can measure one parameter at a time.

Gupta's technique will allow researchers to do multi-parameter measurements, including flow velocity, temperature and absolute concentrations for multiple molecular species.

Measuring the components and temperatures in combustion has proved challenging, because physical probes would change the properties of a given flame.

Gupta and his postdoctoral assistant Yunjing Li have used photothermal deflection to create changes in combustion temperature with a tunable laser and then detect the change with another laser beam. They have used this technique to measure the concentration of a species within a methane flame, its temperature and its flow velocity.

The researchers shoot a tunable laser beam into the flame. The beam is tuned to the frequency of the molecule the researchers wish to measure, so it only excites those molecules when it hits the flame. The researchers use another laser beam to detect the excited molecules. Gupta and Li concentrated first on OH, the hydroxyl radical, produced during combustion.

"If I detect a signal, I know I've detected hydroxyl," Gupta said. However, detection often proves difficult; the signal can get lost in "noise" that emanates from the detector and the lasers themselves. To combat this noise, the researchers take measurements over a 50-second interval--500 pulses at 10 pulses per second--and integrate the signal; random noise drops out over time, but the molecular signal remains.

Fifty seconds is a long time in combustion. "In a flame, things are changing very fast," Gupta said. He and his team are continuing attempts to increase the signal-to-noise ratio and therefore decrease the time needed for detection.

"Ideally, we would like to have a measurement in a single pulse," he said.

This work is supported by the Army Research Office.


Story Source:

The above story is based on materials provided by University Of Arkansas. Note: Materials may be edited for content and length.


Cite This Page:

University Of Arkansas. "University Of Arkansas Physicists Develop Laser Probe For Multi-Parameter Measurements In Combustion." ScienceDaily. ScienceDaily, 25 June 2002. <www.sciencedaily.com/releases/2002/06/020625064233.htm>.
University Of Arkansas. (2002, June 25). University Of Arkansas Physicists Develop Laser Probe For Multi-Parameter Measurements In Combustion. ScienceDaily. Retrieved December 20, 2014 from www.sciencedaily.com/releases/2002/06/020625064233.htm
University Of Arkansas. "University Of Arkansas Physicists Develop Laser Probe For Multi-Parameter Measurements In Combustion." ScienceDaily. www.sciencedaily.com/releases/2002/06/020625064233.htm (accessed December 20, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Saturday, December 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Building Google Into Cars

Building Google Into Cars

Reuters - Business Video Online (Dec. 19, 2014) Google's next Android version could become the standard that'll power your vehicle's entertainment and navigation features, Reuters has learned. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
AP Review: Nikon D750 and GoPro Hero 4

AP Review: Nikon D750 and GoPro Hero 4

AP (Dec. 19, 2014) What to buy an experienced photographer or video shooter? There is some strong gear on the market from Nikon and GoPro. The AP's Ron Harris takes a closer look. (Dec. 19) Video provided by AP
Powered by NewsLook.com
Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Buzz60 (Dec. 19, 2014) A double-amputee makes history by becoming the first person to wear and operate two prosthetic arms using only his mind. Jen Markham has the story. Video provided by Buzz60
Powered by NewsLook.com
Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins