Fueling the Flame of Combustion

by Michael Mullaney on November 11, 2010

By now you’ve likely heard about Professor Matt Oehlschlaeger getting serious accolades from the White House for his fascinating research into better understanding jet fuels and improving jet engines. If not, check out the story here.

What we don’t mention in the story is that Oehlschlaeger heads up Rensselaer’s Combustion Lab. As the name implies, it’s a lab dedicated to studying how stuff burns. After walking into the Combustion Lab, it’s impossible not to notice the shock tube. It’s a metal tube that stretches much of the length of the lab, probably measuring about 10 meters in length and 20 centimeters in diameter.  There’s also a second, smaller shock tube elsewhere in the lab.

These shock tubes are critically important to the combustion research done by Oehlschlaeger and his team of students. The shock tubes use supersonic shock waves to heat and pressurize gas mixtures, mimicking the conditions found in jet or auto engines. When the researchers turn on the machine to initiative a shock wave, there is a loud “thud” sound and the shockwave travels down the stainless steel tube at anywhere from 2 to 10 times the speed of sound – or between Mach 2 and Mach 10. That’s quite fast. In the wake of the shockwave, peak temperatures in the tube can reach thousands of degrees Fahrenheit, and peak pressures can reach up to a 100 times the atmospheric pressure.

These hot, dense, and nasty conditions enable Oehlschlaeger to simulate the conditions found in engines, and allow him to study how fuels combust. His research delves deeply into fundamental chemistry, and one of his primary interests is to study the potential for using alternative fuels, derived from biomass and other sources, for aviation. Though it will be quite some time before we ever see jets running on anything but hydrocarbon-based jet fuel, he said, there are still near-term opportunities for leveraging a richer understanding of fuel chemistry to inform better performing and more fuel-efficient designs for jet engines.

You can see a picture of the shock tube above, and some great footage of the shock tubes and the rest of the Rensselaer Combustion Lab in this YNN news clip from Monday evening on Oehlschlaeger.

Read more about Oehlschlaeger’s award in this Associated Press piece and Troy Record story.