7/31/97
CONTACT: David F. Salisbury, News Service (415) 725-1944;
e-mail: david.salisbury@stanford.edu
Stanford researchers will have access to the world's largest supercomputers and use them to create advanced simulations that will make possible a new paradigm for aircraft engine design as part of the Department of Energy's Accelerated Strategic Computing Initiative (ASCI). Stanford scientists will receive $20 million over five years for this purpose.
The ASCI program was begun in 1995 when the United States decided to maintain its stockpile of nuclear weapons through a scientific stewardship program without further underground nuclear tests. The key to this approach is to develop the advanced computer modeling techniques that allow the government to maintain the safety, reliability and performance of U.S. nuclear weapons through virtual rather than actual testing. A critical aspect of the program is accelerating the development of high performance computer modeling and simulation capabilities.
Stanford will receive one of five academic "centers of excellence" announced by Secretary of Energy Federico F. Peña on Thursday. The Department of Energy will establish these centers as part of a strategic alliance with leading universities designed to advance the state-of-the-art in high performance, computer-based modeling and simulation. They will use advanced computer simulation techniques to study important unclassified technical problems. Not only will the DOE invest approximately $250 million in unclassified university research over the next decade, it will also give the university centers access to an unprecedented level of computing power: about 10 percent of the operating time of the department's new, massive supercomputers. This approach is designed to speed the development of new computational models and methods that will apply to a variety of major national problems and also can be adapted by the DOE's Defense Programs for strategic weapons analysis.
Stanford was chosen as one of the five ASCI centers of excellence from 48 university proposals. The center, which will involve faculty in several engineering departments, will be directed by William C. Reynolds, professor of aeronautics and astronautics and mechanical engineering. It is named the Center for Integrated Turbulence Simulations (CITS).
The center will use computer simulations to model the complex turbulent flows that occur in propulsion systems. It also will integrate these simulations with models of heat transfer, aeroelasticity, chemistry, and other phenomena important in such engines. The core program, which will receive DOE support, will specifically address aircraft gas turbine engines.
The first component in an aircraft jet engine is the compressor, which raises the pressure of the air flowing through the engine. The efficiency of the engine is strongly dependent on the quality of the air flow through the compressor. Improper flow patterns can cause compressor-blade vibrations that can cause premature engine failure. A good engine design requires large investments in testing because the flows that occur in compressors are not now adequately predictable. A goal of the center is to be able to predict these complex flows, predict the compressor performance under all possible operating conditions, and investigate flow-driven blade vibration problems, thereby dramatically reducing the need for costly testing.
The second element in the engine is a combustor into which fuel is sprayed and burned to produce hot gas. Well-controlled turbulent combustion is important for minimizing pollution. Accurate simulations of the turbulence and chemical reactions should lead to new configurations that can operate safely with reduced emissions and improved engine performance.
The final part of a gas turbine engine is the turbine itself, which extracts power from the hot gas emerging from the combustor. The hot turbulent flow requires that the turbine blades be cooled. With more accurate simulation capabilities, the amount of cooling required can be reduced, leading to higher engine efficiency.
"Aircraft engines are a relatively mature technology," Reynolds said. "New improvements come very hard, but they are still crucial. A few percent improvement in the performance of the engine can make the difference in airplane purchases, which are a critical factor in the US balance of trade."
In addition to the work on turbulent flow modeling and simulation, the center will also conduct research on computer systems and architectures for future large-scale scientific computing. This research will draw upon the experience and needs of the turbulent flow simulations, and will be led by Engineering Dean John Hennessy. It will help transfer the new simulation-based design paradigm to industry and government laboratories.
The four other centers of excellence named by Peña are the University of Illinois at Champaign-Urbana, which will simulate advanced rocket designs; the University of Utah, Salt Lake, which will model accidental fires and explosions; the California Institute of Technology, which will create virtual shockwaves; and the University of Chicago, which will simulate the thermonuclear processes that take place within stars.
Fluid mechanics is a key discipline at each of these centers and all of the flows they will study involve turbulence. So the turbulence simulation work at Stanford will provide important input to the other four ASCI centers.
The main portion of CITS will be co-located with the Stanford's Center for Turbulence Research (CTR), which has been developing the fundamentals of new turbulence models and simulation methodologies for the past decade. The ASCI center will serve as a primary means for bringing CTR's fundamental advances to bear in advanced propulsion system design.
More information about the Stanford center is available on its web page (http://www-fpc.stanford.edu/CITS) or by email (info@cits.stanford.edu).
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By David F. Salisbury