Public Release: 

Aerospace Experiments Improve Safety In Jet Aircraft Design

University of Cincinnati

Cincinnati -- University of Cincinnati engineers have developed an experimental system that should help improve a critical area of aircraft design: how to fit a jet engine into an airplane's body.

Doctoral candidate Donald Freund described the system this month at the AIAA Joint Propulsion Conference in Lake Buena Vista, Florida, along with results of preliminary experiments. The work is being performed under the supervision of UC aerospace professor Miklos Sajben in cooperation of Dr. John Slater from NASA Lewis Research Center in Cleveland.

Sajben, an Ohio Eminent Scholar, explains that the work is about matching together two major components of jet propulsion systems, the inlet and the engine. The inlet is the hole in front of the plane that "swallows" the air for the engine.

Engines and inlets are generally built by different companies, using different methods and computer codes. So, it is difficult to predict how they will work once they are put together, especially at the high speeds of future supersonic airliners.

"Stability is a big problem", said Sajben. "Flying into a gust or turbulence could end up literally stopping the air flow through the entire propulsion system, a potentially catastrophic result. To avoid this, the inlet-engine system has to be designed just right".

The aircraft industry has been well aware of the problem for years, and many tests have been performed to make the system safe. Unfortunately, such tests can only be run after the full- scale system is available. At that stage, it is much more expensive to fix any problems. It would be far better if engineers could predict what will happen earlier in the design process.

The problem is that the computer codes used to design the inlet and the engine have difficulty "talking" to each other. Some hard-to-get experimental information is needed to "glue" these codes together. This information has not been available, and computer specialists had to rely on assumptions which made the results less reliable.

This is where the UC research is expected to make an impact. Sajben and Freund combined a small jet engine with a special inlet and developed a new way to obtain the needed information accurately. The system is small and much less expensive than full-scale systems, so many tests can be run under many different types of conditions. The information generated will make it easier for the two codes to talk to each other.

"The end result is a system that fits together better and a system that will be safer and more efficient," said Sajben. "This is something every aircraft company will be able to use."

In fact, the aerospace industry has already shown a serious interest in the UC experiment. Researchers at the NASA Lewis Research Center and at Boeing Aerospace are both doing related computational work on the problem, and NASA is cooperating with a team of Russian researchers on a similar experiment at Russia's Tupolev aircraft plant.

Sajben and Freund successfully completed three of the four stages of their project. The final stage, where the payoff lies, is under way and data collection will start either late summer or early fall of this year.

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