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APPLYING NASA SHUTTLE ENGINE TEST FINDINGS MAY SAVE AIRLINES MILLIONS IN FUEL COSTS

APPLYING NASA SHUTTLE ENGINE TEST FINDINGS MAY SAVE AIRLINES MILLIONS IN FUEL COSTS

Jim Cast, June Malone

Results from tests aimed at improving the performance of

NASAs Space Shuttle engines are expected to save airlines

millions of dollars in fuel costs each year.

The tests, performed at NASA’s Marshall Space Flight

Center in Huntsville, AL, have led to improvements in the

design of a new, more fuel-efficient jet engine for the

Boeing 777.

A full half-percent was gained in energy efficiency —

meaning a savings of hundreds of gallons of fuel per flight

and annual savings of millions of dollars for the airline

industry.

Tests performed at Marshalls turbine airflow test

facility in 1992 were a joint project by NASA and Pratt &

Whitney, a leader in commercial and military aircraft engine

design and manufacturing.

Analyzing the test results, engineers noticed that the

information showed the effects of small fluttering “wakes” of

gases — the unsteadiness of gases flowing through the

turbine airfoils — on turbine efficiency. A turbine is a

mechanical device used to provide power or thrust in rockets

or jet engines. The turbine is similar in concept to a

household fan: The fan rotates with blades on a shaft, just

as a turbine rotates on a shaft with layers of blades, called

airfoils.

Engineers explored the existence of an “optimum

position” for the turbine airfoils, which could mean less

energy to drive the turbines, resulting in lower engine

temperatures, longer-lasting hardware, less maintenance time

and lower operational costs.

Marshall and Pratt & Whitney engineers then repeated the

initial tests, this time for the engine of the wide-bodied

Boeing 777 aircraft, which was to be put into commercial

service in 1995.

Stephen Gaddis, project engineer in Marshall’s

Structures and Dynamics Laboratory where the tests were

conducted, explained, “Wakes flowed through the turbine

airfoils, coming out high in some places, low in others. We

knew if we could align the airfoils or wakes, we could also

get the peaks and valleys to align — all for better turbine

efficiency.”

The principle is much like one used by competitors in

bicycle races: A cyclist will move in behind another racer

to benefit from “drafting” created by the front cyclist. The

biker in front serves to break the winds’ force, so the

cyclist in the rear does not have to pedal as hard as the

leader. Pratt & Whitney took these findings and modified

their PW-4084 engine for the Boeing 777.

“We had been looking for ways to achieve efficiency

improvement,” said Frank W. Huber, manager of turbine

aerodynamics for Pratt & Whitneys Government Engine Division

in West Palm Beach, FL. “The clocking concept — the

aligning of the airfoils — was not new, but there were not

sufficient data to validate this technique.”

“The tests at Marshall demonstrated that the concept

worked — clearly showing the benefit of aligning the turbine

airfoils,” said Huber. “We ultimately found that we could

achieve significant improvement in engine performance.”

Technology developed by NASA has given Pratt & Whitney

and the Boeing Company a competitive edge in world markets,

with an aircraft engine that can realize substantial fuel

savings.

Today, both government and private industry researchers

are using the Marshall test results to fine-tune the large,

electricity-generating turbines used by America’s electric

companies, in an effort to save fuel.

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