Powering the Future

By Jodi Wagner

Doug Thomsen ’93 always liked to burn things. So it seemed natural that he’d build on his Walla Walla University mechanical engineering degree by accepting a full-ride scholarship to study combustion at Purdue University. There, he earned a doctorate degree, and nearly a decade later, his fascination with fire has proved quite useful—he has helped to design the most powerful gas turbine engine in the world.

What is your role at GE Aviation?
My title is senior engineer for combustor aero technology and design at GE Aviation, and I work as combustor aero team leader for the GEnx Engine program. The GEnx Engine is a new centerline engine designed to power the Boeing 787 Dreamliner and 747-8.
My office is in Springdale, Ohio, but testing for the engine project takes me to our main plant in Evendale and to our engine test facilities near Peebles, which is in the Appalachian foothills of South Central Ohio. I also travel to our flight test operations headquarters in Victorville, Calif., on the edge of the Mojave Desert.

How has your work with the GEnx program evolved to where you are today?
I started working on the GEnx program in 2004, although the technology programs supporting it started long before that. When I joined GE in 1999, they were already working with NASA to develop a new generation of low-emissions, gas-turbine combustors. My first program was an internally funded effort to take these technologies, improve and demonstrate them in a commercial CFM-56 engine. This was a very successful program for which my boss received GE’s highest award, the Edison Award.
Basically, to get more efficient, engines have to get hotter. But high temperatures in the combustor result in high amounts of nitric oxide production, a greenhouse gas that also impacts ozone depletion and when emitted near the ground becomes nitrogen dioxide, a basic component of smog. Our combustor seeks to change the way fuel is burnt in order to minimize the peak flame temperature and enable a more efficient yet environmentally sound engine. To bring this technology to production has taken over a decade of labor by a combustor team varying in size from a handful of engineers in the beginning to 20 or so on the current program. Our team is divided roughly in half between mechanical and aero design engineers. In addition to our combustor team, bringing this to production has required working with test organizations, systems, controls, operability and performance groups within the company. Overall, there are hun-dreds of engineers working on this engine program.

What has surprised you during the course of your work? What discoveries have you made?
The most surprising thing about a gas turbine combustor is that it is small. Imagine taking a fire hose and shooting it through a coffee can with the bottom cut out. Now imagine that instead of water you are flowing kerosene and by the end of the can all the fuel must be burnt, products mixed out and a uniform temperature obtained to prevent hot streaks from destroying the turbine.
In the early days of gas turbine propulsion the combustor was the biggest component, stretching more than 2 to 4 feet in length in order to meet these requirements. Today, the biggest commercial gas turbine engines have combustors 6 inches in length. There isn’t a day that goes by that I’m not amazed that it works at all.

How will your work and this project impact the aviation industry?
I see this program as the beginning of a new generation of low-emissions combustors. High fuel prices and global warming concerns will continue to drive the need for high efficiency and low emissions. This design and others like it will continue to be optimized and improved over the coming years as we gain field experience and apply our learning.
On a personal level, I look forward to the day I step onto a commercial airliner and see my engine on its wings.

What do you enjoy most about your work?
The best thing about my job is that gas turbines are endlessly fascinating. You have parts rotating at a couple thousand revolutions per minute, flowpath temperatures over 3000 degrees Fahrenheit, and pressures exceeding 700 psi. On top of this, we want to be able to light the engine at 30,000 feet; accelerate it from idle to takeoff in a few seconds; ingest birds, rain, hail, snow, and ice; and do it all with a reliability that ensures the health and safety of the hundreds of thousands of passengers flying in commercial aircraft on a daily basis.
The combustor is just one part of this story, but the first day you test your design is like a first date. You are excited and nervous, confident but a little scared. My best moments at GE have been in the testing arena. Whether I am running a single-cup prototype burner in a test cell or flying at 5,000 feet over the Mohave Desert trying not to lose my lunch, watching my design become reality is priceless.

What prepared you for the work you’re doing today?
I graduated from Walla Walla with a mechanical engineering degree, and that degree prepared me well for my work as the combustor aero team leader on this program. When people think of mechanical engineering they think you must like tinkering in your garage. While that has some appeal, the other side of mechanical engineering is the thermal sciences, to which I have dedicated my professional career.
A lifetime pyromaniac, I took my fascination with fire and got a PhD in combustion from Purdue University. Now I have made a career out of burning things. Combustion is the ultimate science—it takes the fields of chemistry, thermodynamics, heat transfer, fluid mechanics, physics and turbulence theory and merges them together. Because of its complexity, the field is far from mature, and science often becomes art. One of my colleagues often says that engineering is the art of making sound technical decisions based on incomplete and often erroneous information. Those who seek absolute answers and cut-and-dried results better stick to the pure sciences. Engineering is much more frustrating, painful, experimental and ultimately rewarding than that.

How can tomorrow’s engineers pursue the kind of work you’re doing?
If you want a job right out of school, co-op. Most companies in the industry use their co-op programs as screening tools for their direct hire programs. While they are no guarantee of employment, the programs give you a chance to see if the company fits your interests and career goals. In and provide valuable experience, even if you decide to go a different direction with your career. If you wish to get a graduate degree, recognize that many companies offer educational programs at work so that you can get a good salary and seniority while finishing your education.
There are a lot of jobs in the aerospace industry, although hiring is cyclical. If your preferred job is not available when you are ready to interview, consider grad school. You can gain valuable knowledge while waiting for the job market to open up again. If you are interested in a PhD, consider your interest and go to a school that has recognized expertise in that area. Also, choose a grad school with a professor who has ties to the industry you eventually want to work in. That first connection and referral are your most likely paths to future employment. That is how I got my job.
You will find that the fundamental education you received at Walla Walla University will have prepared you well for your graduate level work. I was specifically surprised to find that my undergraduate math background was in many ways superior to that afforded many of my grad school colleagues.

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Last update on January 21, 2009